Unraveling the contribution of G x E x M interactions to maize productivity in Central Mozambique amid climate change

Unraveling the contribution of G x E x M interactions to maize productivity in Central Mozambique amid climate change | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Unraveling the contribution of G x E x M interactions to maize productivity in Central Mozambique amid climate change Wilson Jose Leonardo, João Vasco Silva, Latha Nagarajan, Upendra Singh This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5922699/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Maize ( Zea mays L.) is the most important cereal staple in sub-Saharan Africa. Yet, smallholders only produce about 20% of what is biophysically possible with agronomic best practices. On-farm researcher- and farmer-managed experiments were conducted in two consecutive cropping seasons in Central Mozambique to disentangle the relative contribution of genotype-by-environment-by-management (G x E x M) interactions to smallholder maize yields in relation to improved varieties, sowing time, and fertilization regime. In the 2022-2023 cropping season, maize yield variability on fertile fields was explained by a three-way interaction between fertilizer regime, sowing date, and variety, whereas on infertile fields, it was explained by fertilizer regime only. The highest yields were obtained with early sowing of a medium- (3.6 t ha -1 ) or early- (3.1 t ha -1 ) duration variety, whereas late sowing yielded the least (1.6 t ha -1 ). In the 2023-2024 cropping season, characterized by El Nino-induced drought, yield variability on fertile fields was explained by variety, with the highest yield associated with the medium-duration variety, and on infertile fields by fertilizer regime. On farmer-managed experiments, maize yield variability was attributed to variety and fertilizer. Profitability with the improved varieties and mineral fertilizers tested depended upon soil fertility and the magnitude of water limitation on maize growth, with trade-offs arising between food security and return on investment in improved genetics and agronomic management. Targeting medium-duration maize varieties in combination with early sowing and nutrient inputs was found to be critical for food security amid climate change. Food security genetics agronomy smallholder farmers profitability Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 1. Introduction Agriculture is the main source of livelihood for smallholder farmers in sub-Saharan Africa. Yet, the region has the lowest agricultural productivity worldwide (Giller et al. 2021 ). For maize, the most important cereal staple in the region, smallholders typically produce about 20% of what is biophysically possible with agronomic best practices (Assefa et al. 2020 ; Silva et al. 2023a ; van Ittersum et al. 2016 ). Such a large yield gap, i.e., the difference between the water-limited potential yield and the actual farm yield under rainfed conditions (van Ittersum et al. 2016 ), is the result of multiple agronomic and biophysical constraints. Poor agronomy is associated with suboptimal crop stands (Nyagumbo et al. 2024 ), late planting and weeding (Leonardo et al. 2015 ), and declining soil fertility due to continuous cultivation with limited external fertilizer inputs (Bekunda et al. 2010 ; Tittonell and Giller 2013 ). Climate variability and change, particularly erratic rainfall, further exacerbate the risks of rainfed crop production (Cairns et al. 2021 ), often compromising the return on investment in fertilizer (Bonilla-Cedrez et al. 2021 ). Sustainable crop intensification is required to meet the future food demand in sub-Saharan Africa (Jayne and Sanchez 2021 ; Vanlauwe and Dobermann 2020 ). Crop yields are the result of genotype-by-environment-by-management (G × E × M) interactions (Evans and Fischer 1999 ,; Fischer 2015 ). Varieties of maize with improved genetics that have been adapted to the current climate are available to smallholders in the region (Cairns et al. 2021 ) and are often adopted with positive impacts on maize productivity and farmers’ livelihoods (Ngoma et al. under review; Evenson and Gollin 2003 ). While climate change is projected to have a negative impact on cereal production across the region (Haile et al. 2020 ; Cairns et al. 2013 ), such effects can be partially offset with existing cultivars (Alimagham et al. 2024 ). Climate change impacts on crop production will depend on the soil fertility status and agronomic management, which can be influenced by farmers at the start of and throughout the growing season. For instance, Descheemaeker et al. ( 2020 ) found that soil fertility is as important as climate change in explaining future farm performance in Southern Zimbabwe. Therefore, disentangling the relative importance of G x E x M interactions on crop yield is key in identifying opportunities for sustainable crop intensification attuned to local conditions. According to the Global Climate Risk Index 2021, Mozambique is the country most affected by and least prepared for climate change (Eckstein et al. 2021 ). Droughts, floods, and cyclones occur with increasing frequency in the country, leading to devastating outcomes for insufficiently prepared farmers who rely on rainfed agriculture. Agriculture is dominated by small-scale farmers (about 98%) who primarily produce for their own consumption (MADER 2024 ). About 10% use improved seeds, 8% use inorganic fertilizers, 7% have access to extension services, and less than 1% have access to agricultural credit ( ibid ). In Mozambique, a country with relatively abundant land, maize is the most important food and cash crop for smallholders, cultivated on nearly 40% of all cropland under smallholder agriculture ( ibid ). Yet, it is also the crop most vulnerable to climate variability, exposing smallholders to food insecurity. Past increases in maize production in the country were achieved through cropland expansion (Leonardo et al. 2018 ) rather than productivity increases on existing cropland. However, increasing production through cropland expansion is limited by labor availability (Baudron et al. 2012a ; Leonardo et al. 2018 ) and associated with greenhouse gas emissions and biodiversity loss (Beyer et al. 2022 ). Increasing crop production per unit area through increases in fertilizer use and adoption of improved crop varieties and good agronomic practices will be required to curb land conversion to agriculture and achieve self-sufficiency of maize at the national level. The objectives of this study were twofold: (1) disentangle the relative contribution of G x E x M interactions to smallholder maize yields in Central Mozambique and (2) explore options for sustainable intensification of maize production amid soil fertility and rainfall variability. Researcher- and farmer-managed on-farm experiments were established in fields with varying soil fertility statuses to assess how different maize varieties respond to changes in sowing date and fertilizer regime over two cropping seasons. The experiments were conducted in Buzi District, a region severely affected by recent extreme weather events, such as Cyclone Idai in 2019, Tropical Storm Chalane in 2020, Cyclone Eloise in 2021 (Crawford et al. 2023 ; Mashula et al. 2021 ; Speight et al. 2023 ), and the 2024 El Niño-induced drought (Fig. 1 a). We hypothesized that maize yield response to improved varieties and sowing date is conditional on nutrient availability, which remains the most limiting factor to maize yields in the study area. This study contextualizes the benefits of improved agronomic practices and improved plant genetics for smallholder maize production under climate change. 2. Material and methods 2.1 Site selection and characteristics Researcher-managed experiments were conducted on-farm in two consecutive cropping seasons (2022-2023 and 2023-2024) in Buzi District, Central Mozambique. The study area lies within 19°55'53.1"S, 34°25'46.3"E in Bandua and 19°56'56.7"S, 34°32'50.6"E in Inharongue. These sites were selected due to their importance for maize production, diversity of soil types, and high frequency of extreme weather events. The main soil types found in the study area are Mollic Fluvisols and Eutric Fluvisols. The district has a tropical humid climate, with a hot, wet season from November to March and a cool, dry season from April to October. The unimodal rainfall pattern allows for only one cropping season (wet season) per year. The rainfall anomaly (i.e., the difference between the 2023-2024 cropping season rainfall and the 30-year average growing rainfall) across Southern Africa is displayed in Fig. 1a and Fig. S1. Rainfall measured in the study sites during both cropping seasons is displayed in Fig. 1b. Heterogeneity in soil fertility status is a common feature of smallholder agriculture. Recognizing this diversity is important for targeting appropriate soil fertility management practices (Tittonell et al. 2005). Four focus group discussions with farmers, with six men and six women participating in each, were organized to identify the most common soil types for the researcher-managed experiments. Based on soil water-holding capacity, soil texture, and farmers’ experience in cultivating maize on their fields, two types of soil were identified and classified by farmers as having high and low soil fertility, categorized as fertile fields and infertile fields, respectively. In the 2022-2023 cropping season, four experiments (two in fertile fields and two in infertile fields) were established and managed by agronomists. In the 2023-2024 cropping season, the number of fields managed by agronomists was increased to five (one in a fertile field and four in infertile fields). Farmers strongly prefer fertile fields; therefore, in the second season, we failed to find any farmers who were willing to use their fertile land for the experiment. An additional 33 farmer-managed experiments (four in fertile fields and 29 in infertile fields) were conducted in the second cropping season to capture variability in the response to the tested treatments across a wider range of soil and management conditions. The experimental design was the same as in the researcher-managed experiments. Apart from fertilizer application, all farming activities in these fields, i.e., sowing, weeding, and harvesting, were performed by the farm household. 2.2 Experimental design, treatments, and crop management Researcher- and farmer-managed experiments were designed as a randomized complete block. The main factor evaluated was sowing date, which included three times: early sowing in November, intermediate sowing in December, and late sowing in January. In the 2023‑2024 cropping season, only one sowing date was possible due to the severe drought and early cessation of rainfall caused by El Niño (Fig. 1). The second factor evaluated was maize variety: a short-duration hybrid variety with 110-115 days between sowing and maturity (DKC-80-33 in the 2022-2023 cropping season and MH43A in the 2023-2024 cropping season) and a medium-duration hybrid variety with 115-130 days between sowing and maturity (DK777 in both cropping seasons). Different early-duration varieties were used in the two cropping seasons because farmers were not interested in cultivating DKC-80-33 in the second season due to its poor storability. The third factor evaluated was fertilizer regime, either with or without mineral fertilizer application. The source of nutrients used in the experiment was the commonly available fertilizer blend NPK 23:10:5+6S+1Zn applied basally at a rate of 125 kg ha -1 . Urea (46% N) was applied at knee-high stage, depending on moisture availability, at the same rate as the basal application. This translates to a total of 86.3 kg N ha -1 , 22.9 kg P 2 O 5 ha -1 , and 6 kg K 2 O ha -1 . Such design allowed us to elucidate the relative contribution of G × E × M interactions, since the sowing dates reflect different E × M interactions on maize yield, the two varieties reflect the contribution of G on maize yield, and the two fertilizer regimes reflect the contribution of M on maize yield. Cropping season and soil fertility status are other important components of E considered in our experimental setup. The area of cultivation for each sowing date consisted of five blocks, each with four plots of 5 m × 8 m, and five replications per treatment and per sowing date. Maize was planted at a spacing of 0.75 m × 0.50 m, with two plants per station, targeting a plant population at sowing of 53,333 plants ha -1 . On researcher-managed experiments, land preparation (plowing and harrowing) was done with a tractor, allowing the incorporation of crop residues from the previous cropping season. To avoid the residual effects of fertilizers, new adjacent fields were selected in the second cropping season. On farmer-managed experiments, most land preparation was done manually or using oxen. For all experiments, maize was the previous crop. Sowing, fertilizer application, and weeding were done manually in all experiments. No irrigation was supplied, and the first sowing date was determined by the soil moisture content. Rainfall was measured daily using a rain gauge from the time of planting to harvesting at each site and recorded by the field technician and lead farmers. During the growing season, the crop was treated with commercial pesticides to control fall armyworm when the risk of infestation existed. 2.3 Soil analysis, maize grain yield, and plant population Soil samples were collected following a zig-zag pattern within each field prior to sowing and fertilizer application. A total of eight samples were taken using a soil auger at 0-20 cm and 20-40 cm depths. An air-dried sub-sample of about 0.5 kg from each depth was analyzed at Crop Nutrition Laboratory Services in Nairobi, Kenya. The sub-samples were oven-dried, passed through a 2 mm sieve, and analyzed for pH (H 2 O) following the potentiometric method; available P, exchangeable K + , Ca 2+ , Mg 2+ , Na + , Zn 2+ , Mn 2+ , Cu 2+ , S, and B following the Mehlich-3 inductively coupled plasma (ICP); exchangeable aluminum following the colorimetric method; total N following the Kjeldahl method; soil organic carbon (dry combustion); and texture following the hydrometer method. At maturity, the two middle rows of each treatment plot were harvested, leaving two plants at each end of the row (net harvest area). All plants in the net harvest area of each plot were cut at surface level, and the total aboveground biomass (stems, leaves, and cobs) was weighed. A subsample of 10 plants was randomly taken from the harvested plants and weighed. If the yield was poor, as in the second cropping season on infertile fields, all biomass from the net harvest area was considered for the final measurement. The cobs from subsamples or the net harvest area were separated from the plants, and both weights were taken separately. Then, cobs and stalks (stems and leaves) were air-dried for about two weeks, threshed, and weighed, and the moisture content was determined with a grain moisture meter. Grain yields were adjusted to a moisture content of 12 %, as follows: Grain yield (at 12 % grain moisture) = grain yield fresh * (100 – fresh grain moisture %) / 88 % The maize plant population was determined at harvest by counting the number of plants in each net harvest area. 2.4 Economic assessment An economic assessment of the treatments tested in the researcher-managed experiments in the two cropping seasons and in the farmer-managed experiments in the 2023-2024 cropping season was conducted based on the profit and returns on investment associated with capital inputs (i.e., seed and fertilizer). Profit (USD ha -1 ) was calculated as the difference between gross return and input costs. Return on investment (USD USD -1 ) was calculated as the ratio between gross return and input costs. Gross return was calculated by multiplying the maize yield in each treatment by the market price of maize, USD 0.22 kg -1 , regardless of variety type. The price of maize was estimated as the average of three farm-gate prices in the study region: the price at harvest (April to July), during the intermediary period (August to November), and during the lean period (December to March). Input costs were calculated as the sum of seed costs and fertilizer costs. Seed costs were calculated by multiplying the amount of seed used for each treatment by the price of the seed: USD 3.3 kg -1 for the early-duration variety DKC-80-33 (seed amount equal to 23.3 kg ha -1 ), USD 2.4 kg -1 for the early-duration variety MH43A (12.5 kg ha -1 ), and USD 3.3 kg -1 for the medium-duration variety DK777 (14.8 kg ha -1 ). Fertilizer cost was calculated by multiplying the amount of urea and NPKSZn fertilizer used in each treatment by the respective market price in the study region, USD 45 per 50-kg bag for both fertilizer types. Seed and fertilizer costs for each variety and fertilizer type were obtained from local agro-dealers in the study region. 2.5 Data analysis Statistical analyses were conducted using linear mixed models fitted to different subsets of the data. Treatment effects on maize grain yield were assessed separately for researcher-managed experiments conducted in fertile and infertile fields in each cropping season and for farmer-managed experiments conducted in fertile and infertile fields in the 2023-2024 cropping season. The analyses were done separately for these different subsets of data due to large differences in rainfall between the two cropping seasons (Fig. 1), which compromised the second and third sowing in the 2023-2024 cropping season, resulting in unbalanced data, and due to differences in indigenous soil fertility (fertile vs. infertile fields; Table 1) and trial management (researcher vs. farmer management). The linear mixed models fitted for researcher-managed experiments in fertile and infertile fields conducted in the 2022-2023 cropping season tested a three-way interaction between the fixed effects: variety type, sowing time, and fertilizer regime. For the researcher- and farmer-managed experiments conducted in the 2023-2024 cropping season, the fitted linear mixed models tested a two-way interaction between the fixed effects: variety type and fertilizer regime. All models considered the replicate within each farm (i.e., its identifier) as a random effect, except in the case of fertile fields in the 2023-2024 cropping season, where only replication was considered as a random effect since only one farm hosted the researcher-managed experiment on a fertile field during this cropping season. Linear mixed models were fitted with restricted maximum likelihood using the lmer() function of the lmerTest R package (Kuznetsova et al. 2017). The statistical significance of the fixed effects and their interaction on maize yield were tested using analysis of variance (ANOVA) with the anova() function of R. Least-square means were then predicted using the fitted models for each variety type x sowing time x fertilizer regime combination using the emmeans() function of the emmeans R package (Lenth, 2024). The same linear mixed model approach was used to test for treatment effects on profit and return on investment. Variability in maize yield response to variety type, sowing time, and fertilizer regime was assessed using cumulative distribution curves (Vanlauwe et al. 2019), computed for each factor independently and for each cropping season x management type (researcher vs. farmer management) combination in both fertile and infertile fields. Cumulative distribution curves provide a measure of the risk associated with each of the factors tested and indicate the likelihood of obtaining any given outcome within the range of outcomes captured in the data. Cumulative distribution curves were developed for absolute maize yield response (i.e., the difference between treatment and control yields) and for relative maize yield response (i.e., the absolute maize yield response relative to the control yield). The early-duration variety, the first sowing date, and no fertilizer use were considered as controls when assessing maize yield response to variety type, sowing time, and fertilizer regime, respectively. Data on the maize plant population at harvest were only collected for the experiments conducted in the 2023-2024 cropping season. Linear mixed models were fitted to assess the effect of variety type and fertilizer regime (two-way interaction) on the maize plant population at harvest on either fertile or infertile fields. The two-way interaction and the fertilizer regime had no statistically significant effect on plant population at harvest in either of the fitted models; hence, data on plant population at harvest were presented for different variety types only. Finally, maize yield response to plant population at harvest was assessed using boundary line functions that depict the maximum maize yield for a given plant population at harvest. As such, input-output combinations that define the boundary function are limited by plant population at harvest, whereas input-output combinations below the boundary function are limited by other factors beyond plant population at harvest. Boundary lines were estimated for the pooled data with quantile regressions fitted to the 90 th and 95 th quantiles using the rq() function of the quantreg R package (Koenker 2024). 3. Results 3.1 Soil fertility status The farmers’ classification of fertile and infertile fields was mostly based on the clay content and buffering capacity among the analyzed soil properties, especially in the subsoil (Table 1). Soil texture was dominated by clay in fertile fields and clay loam to sandy clay loam in infertile fields. The mean measured pH (H 2 O) of the topsoil and subsoil of both fertile and infertile fields ranged from 6.0 to 6.2, which can be classified as optimum for maize crops. Soil organic carbon was also at adequate levels for maize production at 19-24 g kg -1 , while total nitrogen was low, ranging between 1.1 g kg -1 and 1.4 g kg -1 . Phosphorus was at optimum levels for maize crops, between 64.7 mg kg -1 and 90.4 mg kg -1 , whereas potassium was low in the topsoil and the subsoil of both field types, between 139 mg kg -1 and 242 mg kg -1 . Sulfur, magnesium, and zinc were at optimum level in topsoil and subsoil regardless of field type. Boron and calcium were low in the topsoil and the subsoil of both fertile and infertile fields. Table 1 Physical and chemical soil characteristics from the researcher-managed experiments for the 0- 20 and 20-40 cm depth. Soil samples were taken prior to the establishment of the treatments in the 2022-2023 growing season. Exch.Al = exchangeable aluminium; ECEC = effective cation exchange capacity by summation. Topsoil (0-20 cm) Subsoil (20-40 cm) Farmers’ classification Farmers’ classification Properties Units Fertile Infertile Fertile Infertile Particle size distribution Sand % 30.4 36.5 28.6 45.6 Silt % 27.5 27.3 28.2 23.1 Clay % 42.2 36.2 43.2 31.3 Soil texture - Clay Clay loam Clay Sand clay loam Soil C and nutrients Carbon g kg -1 22.6 22.4 24.1 18.7 Nitrogen g kg -1 1.3 1.4 1.4 1.1 Phosphorus mg kg -1 83.2 84.5 90.4 64.7 Sulphur mg kg -1 10.4 10.9 11.7 8.9 Manganese mg kg -1 83.4 75.4 84.6 71.1 Boron mg kg -1 0.8 0.6 0.7 0.5 Zinc mg kg -1 4.8 4.2 4.1 2.9 Soil acidity pH in water - 6.1 6.1 6.0 6.2 Exch.Al meq 100g -1 <0.10 <0.10 <0.10 <0.10 Buffering capacity Calcium meq 100g -1 19.12 16.86 19.09 14.89 Magnesium meq 100g -1 0.70 0.63 0.71 0.59 Potassium meq 100g -1 0.62 0.53 0.57 0.36 Sodium meq 100g -1 0.23 0.19 0.23 0.19 ECEC meq 100g -1 20.66 18.21 20.59 16.03 3.2 Maize yield response to variety type, sowing date, and fertilizer regime In the 2022-2023 cropping season, a significant three-way interaction was observed between fertilizer regime, sowing date, and variety type for maize yield on researcher-managed experiments in fertile fields ( p < 0.01) (Table 2). The highest maize yields on these fields were obtained with early sowing of a medium- (3.6 t ha -1 ) or early- (3.1 t ha -1 ) duration maize variety with fertilizer applied (Fig. 2a). Conversely, late sowing without fertilizer yielded the least on these fields regardless of variety type (about 1.6 t ha -1 on average). No interactions between sowing date and variety type or between variety type and fertilizer regime were observed for this cropping season on researcher-managed experiments in infertile fields (Table 2). Yet, the effect of fertilizer regime was highly significant in these fields ( p < 0.001), with fertilized treatments yielding an average of 2.1 t ha -1 , compared with 1.4 t ha -1 obtained in the unfertilized treatments (Fig. 2b). Maize yields were 23% greater on researcher-managed experiments in fertile fields than infertile fields, showing the importance of soil fertility status on maize productivity and response to agronomic management practices. Table 2 Analysis of variance regarding the effects of variety, sowing date, and fertilizer regime on maize yield in Buzi district, Central Mozambique. Researcher managed experiments were conducted in the 2022-2023 and 2023-2024 cropping seasons. The same experiment was also conducted under farmer management in the latter cropping season. The effect of sowing date could not be assessed in 2023-2024 due to dry spells at the time of sowing Field type Treatment Sum Sq. Mean Sq. NumDF DenDF F-value p-value Researcher-managed experiments (2022-2023) Fertile Sowing 13.9 6.9 2 99 11 <0.001 Fertile Variety 6.0 6.0 1 99 9.5 <0.001 Fertile Fertilizer 18.4 18.4 1 99 29 <0.001 Fertile Sowing x Variety 0.6 0.3 2 99 0.5 n.s. Fertile Sowing x Fertilizer 5.1 2.6 2 99 4.0 0.020 Fertile Variety x Fertilizer 0.3 0.3 1 99 0.5 n.s. Fertile Sowing x Variety x Fertilizer 5.6 2.8 2 99 4.4 0.010 Infertile Sowing 0.3 0.2 2 88 0.3 ns Infertile Variety 0.1 0.1 1 88 0.3 ns Infertile Fertilizer 16.1 16.1 1 88 31.4 <0.001 Infertile Sowing x Variety 0.8 0.4 2 88 0.8 ns Infertile Sowing x Fertilizer 1.00 0.5 2 88 0.9 ns Infertile Variety x Fertilizer 1.0 1.0 1 88 1.9 ns Infertile Sowing x Variety x Fertilizer 1.5 0.7 2 88 1.4 ns Researcher-managed experiments (2023-2024) Fertile Variety 1.7 1.7 1 9 8.2 0.020 Fertile Fertilizer 0.0 0.0 1 9 0.1 n.s Fertile Variety x Fertilizer 0.7 0.7 1 9 3.3 n.s. Infertile Variety 0.6 0.6 1 53 3.6 0.060 Infertile Fertilizer 10.4 10.4 1 53 61.5 < 0.001 Infertile Variety x Fertilizer 0.1 0.1 1 53 0.4 n.s. Farmer-managed experiments (2023-2024) Fertile Variety 2.1 2.1 1 45 13 <0.001 Fertile Fertilizer 5.1 5.1 1 45 30.9 <0.001 Fertile Variety x Fertilizer 0.1 0.1 1 45 0.6 n.s. Infertile Variety 6.9 6.9 1 345 55 <0.001 Infertile Fertilizer 10.3 10.3 1 345 82.1 <0.001 Infertile Variety x Fertilizer 0.2 0.2 1 345 1.9 n.s. In the 2023-2024 cropping season, significant yield differences ( p = 0.02) were observed between early- and medium-duration varieties on researcher-managed experiments in fertile fields (Table 2). Maize yield was an average of 3.3 t ha -1 with the early-duration variety and 4.0 t ha -1 with the medium-duration variety on in these fields (Fig. 2c). Conversely, significant yield differences ( p < 0.001) were observed between fertilizer regimes on researcher-managed experiments in infertile fields (Table 2). In these fields, maize yield was an average of 1.3 t ha -1 with fertilizer and 0.4 t ha -1 without fertilizer (Fig. 2d), substantiating the results of the 2022-2023 cropping season. Maize yield in the farmer-managed experiments conducted in the 2023-2024 cropping season was very low, and maize yield variability was explained by the additive effects of variety type ( p < 0.001) and fertilizer regime ( p < 0.001) in both field types (Table 2). In these experiments, maize yield in fertile fields was highest for the medium-duration variety with fertilizer (1.7 t ha -1 ), followed by the early-duration variety with fertilizer (1.3 t ha -1 ), medium-duration variety without fertilizer (1.1 t ha -1 ), and early-duration variety without fertilizer (0.8 t ha -1 , Fig. 2c). Similar results were observed in infertile fields, where maize yield was highest for the medium-duration variety with fertilizer (0.9 t ha -1 ), followed by the early-duration variety with fertilizer (0.6 t ha -1 ), medium-duration variety without fertilizer (0.6 t ha -1 ), and early-duration variety without fertilizer (0.4 t ha -1 , Fig. 2d). 3.3 Variation in yield response to variety type, sowing date, and fertilizer regime Maize yield response to sowing date, variety type, and fertilizer regime was highly variable across experiments and field types (Fig. 3). Greater maize yield responses were observed for fertilizer regime than for sowing time and variety type. Maize yield responses to fertilizer regime were not only greater but also more consistent since there were more favorable effects on maize yield with the use of fertilizer than with different sowing dates or variety types. The relative maize yield response to sowing date, variety type, and fertilizer regime is provided in Fig. S2. The medium-duration variety outyielded the early-duration variety in 34 out of 60 (57%) of the farms x treatment combinations on researcher-managed experiments in fertile fields and less so in infertile fields, i.e., 25 out of 51 (49%) farms x treatment combinations in the 2022-2023 cropping season (Fig. 3a). In these experiments and cropping season, the medium-duration variety outyielded the early-duration variety by 1 t ha -1 or more on 17 out of 34 (50% ) and five out of 25 (20%) of the farms x treatment combinations in fertile fields and infertile fields, respectively (Fig. 3d), pointing to the benefits of medium-duration varieties in fertile soils. In the 2023-2024 cropping season, two out of six (33%) and (four out 17 (24%) of the farms x treatment combinations showed yield gains with the medium-duration variety equal to or greater than 1.0 t ha -1 on researcher-managed experiments in fertile and infertile fields, respectively. On farmer-managed experiments, the medium-duration variety outyielded the early-duration variety by 1 t ha -1 or more on about 14% of the farms x treatment combinations in both fertile (3 out of 23) and infertile fields (20 out 0f 140). The early sowing date outyielded the intermediate sowing date on 30 out of 40 (75%) of the farms x treatment combinations and the late sowing date on 26 out of 40 (65%) of the farms x treatment combinations on researcher-managed experiments in fertile fields in the 2022-2023 cropping season (Fig. 3b). In these fields, the yield difference between the early sowing date and the intermediate sowing date and between the early sowing date and late sowing date was equal or greater than 1.0 t ha -1 in 77% and 65% of the farms x treatment combinations, respectively (Fig. 3e). In infertile fields, the early sowing date outyielded the intermediate sowing date on 17 out of 33 (52%) and the late sowing date on 11 out of 34 (32 %) of the farms x treatment combinations (Fig. 3b). In these fields, the yield difference between the early and intermediate sowing dates and between the early and late sowing dates was equal to or greater than 1.0 t ha -1 on about 24% and 36% of the farm x treatment combinations, respectively. The effect of sowing date could not be assessed for the 2023-2024 cropping season due to dry spells at the time of sowing. In the 2022-2023 cropping season, the fertilized treatments outyielded the unfertilized treatments on 43 out of 60 (72%) and on 43 out 51 (84%) of the farms x treatment combinations on researcher-managed experiments in fertile and infertile fields, respectively (Fig. 3c). The yield difference between the fertilized and the unfertilized treatments was equal to or greater than 1.0 t ha -1 in 60% and 49% of the farms x treatment combinations in fertile and infertile fields, respectively (Fig. 3f). In the 2023-2024 cropping season, the fertilized treatments outyielded the unfertilized treatments on four out of eight (50%) and in 28 out 33 (85%) of the farms x treatment combinations on researcher-managed experiments in fertile and infertile fields, respectively (Fig. 3c). In fertile fields, the largest yield difference between fertilizer regimes was about 0.7 t ha -1 and was observed in 25% of the farms x treatment combinations. On farmer-managed experiments, the fertilized treatments outyielded the unfertilized treatments on 27 out of 32 (84%) of the farms x treatment combinations in fertile fields. In infertile fields, fertilized treatments outyielded the unfertilized treatments on 160 out of 232 (69%) of the farms x treatment combinations. The yield difference between the fertilized and the unfertilized treatments was equal to or greater than 1.0 t ha -1 in 22% and 13% of the farms x treatment combinations in fertile and infertile fields, respectively. 3.4 Effect of plant population at harvest on maize yield Variety type had a statistically significant ( p < 0.05) effect on plant population at harvest, unlike fertilizer and variety x fertilizer whose effects were not statistically significant at the 5% level. The number of maize plants at harvest differed significantly ( p < 0.05) between the early- and medium-duration varieties on both researcher- and farmer-managed experiments, with a higher number of plants observed for the medium-duration variety (Fig. 4a). Plant population at harvest was higher on researcher-managed experiments at about 42,000 plants ha -1 for the medium-duration variety and 32,000 plants ha -1 for the early-duration variety. The median plant population on farmer-managed experiments was about 28,000 plants ha -1 for the medium-duration variety and 22,000 plants ha -1 for the early-duration variety. The variation in plant population at harvest was larger in the farmer-managed experiments than in the researcher-managed experiments, and the same was true for the maize yields obtained for a given plant population at harvest (Fig. 4b). Overall, the plant population at harvest varied from 5,000 to 65,000 plants ha -1 and from 25,000 to 53,333 plants ha -1 in the farmer- and researcher-managed experiments, respectively. The mean plant population in both experiments was lower than the target value of 53,333 plants ha -1 in this drought-affected cropping season: about 38,000 plants ha -1 in the researcher-managed experiments and 26,000 plants ha -1 in the farmer-managed experiments. The quantile regressions fitted to the 90 th and 95 th quantiles indicated that maize yield was maximized at a plant population at harvest of around 50,000 plants ha -1 , corresponding to 2.0 t ha -1 at the 90 th quantile and 2.6 t ha -1 at the 95 th quantile (Fig. 4b). A plant population at harvest of more than 50,000 plants ha -1 was associated with slight decreases in maize yield, probably due to competition between plants. Results thus show a clear contribution of plant population at harvest to maize productivity as well as the importance of other factors at given plant population levels. 3.5 Profit revenue and return on investment in seeds and fertilizer In the 2022-2023 cropping season, the results showed that it is profitable to grow improved maize varieties in fertile and infertile fields. The profit for the medium-duration variety was higher than for the early-duration variety in fertile (median of USD 370 ha -1 vs. USD 200 ha -1 , respectively) and infertile (median USD 200 vs. USD 100, respectively) fields (Fig. 5a). The maximum profit was about USD 800 for the medium-duration variety and USD 700 for the early-duration variety. The profit for both varieties was comparable across fertilizer treatments, indicating that gains in maize yield due to fertilizer application offset the cost of the fertilizers. The return on investment in improved seed was higher for the early-duration variety than the medium-duration variety and decreased with application of fertilizers; it was slightly lower in infertile fields (Fig. 5d). In the 2023-2024 cropping season, the profit and return on investment were on the margin in researcher-managed experiments for both early- and medium-duration varieties (Fig. 5b). The maximum profit was about USD 100 ha -1 for the varieties. Fertilizer application increased the maximum profit up to USD 250 ha -1 but increased the number of unprofitable fields by nearly 25%. Overall, fertilizer use was unprofitable on farmer-managed experiments, especially in infertile fields, for both varieties (Fig 5c). The maximum profit in fertile fields ranged from USD 100 ha -1 to USD 250 ha -1 . 4. Discussion Improving soil fertility and agronomic management are widely recognized as pathways for sustainable intensification of crop production in sub-Saharan Africa (Kuyah et al. 2021 ). This study investigated whether maize yield response to improved varieties and early sowing was conditional on soil nutrient availability, which remains the most limiting factor to maize yields in African smallholder farming (Bekunda et al. 2010 ; Tittonell and Giller 2013 ), including Central Mozambique (Roxburgh and Rodriguez 2016 ). The experimental approach involved testing two hybrid maize varieties with three sowing dates and two fertilizer regimes over two distinct cropping seasons (one with good rainfall distribution and one characterized by El Niño-induced drought) and two field types (fertile and infertile). This allowed us to disentangle the relative contribution of genotype, environment, and management and their interactions to maize yields and thus to identify the most pressing constraints to farm yields amid climate change and variation in soil fertility. The farmers’ soil fertility characterization mostly considered differences in soil texture across fields and subtle differences in nutrient concentrations in the topsoil and subsoil (Table 1 ). The first cropping season of 2022–2023 was characterized by a normal rainfall amount and distribution (Fig. 1 b), as reflected in the considerably higher maize yields observed in this cropping season compared to the 2023–2024 cropping season, regardless of agronomic management or soil fertility status. Under such conditions, considerable maize yield gains were observed for early- and medium-duration varieties when sown earlier and with the use of fertilizer (Fig. 2 a), with the medium-duration variety outyielding the early-duration variety in 57% of the farms x treatment combinations. The positive impact of improved maize varieties and of medium- vs. early-duration varieties on maize yield is well-established in Southern Africa (Nyagumbo et al. 2017 ; Setimela et al. 2017 ), as is the importance of timely sowing (Rurinda et al. 2015 ), particularly under moderate to high soil fertility. Our results in infertile fields further show that maize yield response to sowing date and variety is only observed with the application of fertilizers, pointing to the importance of fertilizer use to improve soil fertility and increase maize production where soil fertility is poor (Amare et al. 2022 ; Falconnier et al. 2023 ; Silva et al. 2023a ). We also found that sowing an early-duration variety is riskier than sowing a medium-duration variety in infertile fields; hence, the latter is recommended regardless of soil fertility when early sowing can be ensured. Overall, soil fertility management must be prioritized in Central Mozambique in the short term, certainly when favorable rainfall can be expected, and our results provide recommendations to exploit positive interactions between management practices and their associated risk for farmers under such conditions. Despite the El Niño-induced drought in the second cropping season of 2023–2024, the varieties in fertile fields under researcher management reached yields comparable to those obtained in the first cropping season with fertilizer application in the same field type (Fig. 2 c). The good maize yield in this specific field type in a drought year could be attributed to good soil structure and water-holding capacity, indicating some degree of heterogeneity in soil fertility among the fertile fields (Vanlauwe et al. 2007 ). This can be explained by differences in past field management practices, differences in resource endowments between farmers (Giller et al. 2006 ), and landscape position (Amede et al. 2022 ). Conversely, maize yields in infertile fields were much lower in the second season than in the first cropping season, but fertilized plots yielded about twice that of unfertilized plots under researcher and farmer management. The variability in yield response to fertilizer use in infertile fields can be attributed to (1) differing soil sand content and associated soil water-holding capacity, (2) inappropriate fertilizer rates and types, and (3) the calcium and boron deficiencies observed in some fields. Previous studies in smallholder settings also found infertile fields to be unresponsive to fertilizer use (Giller et al. 2011 ; Nziguheba et al. 2021 ) and proposed a focus on integrated soil fertility management as a means to increase and stabilize maize yields in sub-Saharan Africa (Zingore et al. 2008 ). Our findings support such an approach to soil fertility improvement and highlight the importance of adopting improved varieties for food security in dry years under both researcher and farmer management conditions. By including researcher-managed and farmer-managed experiments, this study further allowed an evaluation of the impact of improved agronomic management on maize yield. A large difference was found between the productivity obtained under researcher and farmer management in fertile fields (Fig. 2 c) and in infertile fields where fertilizer was applied (Fig. 2 d). This finding points to the critical role of improved agronomy in maize productivity in Southern Africa (see also (Nyagumbo et al. 2024 ; Roxburgh and Rodriguez 2016 ; Silva et al. 2023a ). In this context, improved agronomy goes beyond timely sowing and fertilizer application, since these operations were also handled by researchers in farmer-managed fields, encompassing timely weeding and management practices that can ensure good crop development and plant population at harvest (Fig. 4 a). For instance, ensuring a plant population at harvest of up to the recommended 53,333 plants ha − 1 can potentially increase maize yield from 0.6 t ha − 1 up to 2.0 t ha − 1 under farmer management, roughly twice the average annual maize consumption in the study region. On farmer-managed experiments, most land preparation was done manually or using oxen, with implications on the quality of the seedbed for seed germination and growth, uniformity of seed depth, and access to soil moisture and nutrients. Therefore, multiple factors may contribute to suboptimal plant population at harvest, including in-season droughts, poor soil fertility, variety choice, and untimely field operations due to resource constraints at critical periods of the growing season (Silva et al. 2019 ; Tittonell and Giller 2013 ). Indeed, late weeding remains a critical yield-reducing factor for crop production in sub-Saharan Africa (Baudron et al. 2012b ; Page et al. 2012 ; Silva et al. 2023a ). In this study, it was not possible to monitor whether weeding on farmer-managed experiments was done at the appropriate time, but the water stress induced by El Niño in the 2023–2024 cropping season might have further increased competition for water and nutrients in the case of late weeding. Future research is required to improve of our understanding of the factors driving suboptimal plant populations at harvest across smallholder production environments in Africa. In addition to agronomic benefits, improved varieties can increase the profitability of smallholder farms in Central Mozambique, particularly in cropping seasons with good rainfall. Our results indicate that nearly half of the farms achieved a profit of USD 350–800 ha − 1 when the medium-duration variety was used without fertilizer application in the researcher-managed experiments (Fig. 5 a). This is substantial, even when labor costs are not accounted for, given that the minimum wage for the agriculture sector in Mozambique is about USD 100 per month (Governo de Moçambique 2024 ) and that smallholders in Central Mozambique farm 1.7 ha on average, slightly above the national average of 1.5 ha (MADER 2024 ). Yet, such short-term benefits will lead to soil fertility decline if improved varieties are cultivated without fertilizer in the same field over time (Bekunda et al. 2010 ; Lal and Stewart 2016 ). The low profitability observed in the farmer-managed experiments (Fig. 5 c) is the result of the El Niño-induced drought. Moreover, investing in improved seeds in infertile soils is often not economically attractive, particularly when fertilizers are used in low rainfall years (Fig. 5 ). The rainfall variability observed across two consecutive seasons shows the risk of investing in fertilizers despite its positive effect on increasing yields. The maize yield in the 2023–2024 cropping season was lower, contributing to lower profitability or even losses when fertilizer was used (Fig. 5 c). If profit and high production are the goals, then fertilizer should be targeted to fertile fields with good water-holding capacity. Earlier studies have highlighted the importance of mineral fertilizers in the sustainable intensification of African smallholder farming as a means to improved soil fertility and replace nutrients (Amare et al. 2022 ; Falconnier et al. 2023 ; Silva et al. 2023b ; Vanlauwe et al. 2014). Yet, smallholders’ access to mineral fertilizers remains limited in Mozambique, when compared with neighboring countries in Southern Africa. The response of early- and medium-duration varieties to fertilizers in our experiments (Fig. 2 ) shows how fertilizers can significantly increase and sustain yields. While the financial analysis indicates that applying fertilizers in a drought year substantially decreases profit, the economic gains can be large in good years. Several studies have indicated the positive impact of smart agro-input subsidy programs on agricultural productivity, food security, and the nutritional status of poor people in sub-Saharan Africa (Haile et al. 2017; Obayelu et al. 2021 ). Mozambique has been implementing agro-input subsidy programs since 2001, yet the outreach is still very low, with only 10% using improved seeds and 8% using inorganic fertilizers. There is a need to combine subsidies with insurance products, such as fertilizer insurance and crop failure insurance, to reduce the negative impact on smallholder farmers’ livelihoods due to poor yields and low profits as a result of erratic rainfall. 5. Conclusions Maize yield variability in Central Mozambique can be explained by the interaction between sowing date, variety type, and fertilizer regime, reinforcing the importance of understanding G × E × M interactions. Overall, the medium-duration variety had better agronomic performance and economic return compared with the early-duration variety. The low return on investment with application of fertilizer serves as a disincentive for farmers to invest on fertilizers under prevailing grain and fertilizers prices. Measures such as smart agro-input subsidies to reduce fertilizer costs are required to improve access for farmers. Otherwise, farmers will likely continue to cultivate maize without fertilizers, which may compromise longer term sustainability of crop production in relation to soil fertility replenishment over time. 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The effect of sowing date could not be assessed in the 2023-2024 cropping season due to dry spells at the time of planting. In the 2022-2023 cropping season, only researcher-managed (RM) experiments were carried out. In the 2023-2024 cropping season, the researcher-managed experiments were complemented with farmer-managed (FM) experiments conducted in the vicinity of the former. Maize yield response to variety (a) was computed as the yield difference between the medium-duration variety (DK777 in both years) and the early-duration variety (DKC80-33 in year 1 and MH43A in year 2) divided by the yield of the early-duration variety in the respective treatments. Maize yield response to sowing date (b) was computed as the yield difference between the two later sowing dates (S2 and S3) and the early sowing date (S1) divided by the yield in the respective S1 treatment in year 1 only. Maize yield response to fertilizer (c) was computed as the yield difference between the fertilized treatments (F1) and the unfertilized treatments (F0) divided by the yield in the respective unfertilized treatment Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-5922699","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":410209268,"identity":"2dcc2520-e2e3-43fe-8160-1a71d4b5809a","order_by":0,"name":"Wilson Jose Leonardo","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAzklEQVRIiWNgGAWjYDACdgjF2MDe2PCBhygtzDAtPAcbZ5CoRSKBkTgtBoeZDz4uqLkn2y/5uLHhTQ2DnHn/AkJa2JKNZxwrNp45O7Gxcc4xBmOZGw/wazE7zGMmzcOWkLjhdmL7Y94GhsQZEgcIaeH/Js3zD6jl5sHGZiK18LBJ87YBtdxghGrhb8Cvxf4wm7Exb1+C8cwesF8kjCUk8OtgkGxvfviY51uCbD/78YfAELORk+An4DB0ALRCIoE0LUBAqi2jYBSMglEw7AEAG5JE5iQELCEAAAAASUVORK5CYII=","orcid":"","institution":"International Fertilizer Development Center","correspondingAuthor":true,"prefix":"","firstName":"Wilson","middleName":"Jose","lastName":"Leonardo","suffix":""},{"id":410209269,"identity":"99097c70-85a7-4b39-848d-7cbb8b24ae67","order_by":1,"name":"João Vasco Silva","email":"","orcid":"","institution":"International Maize and Wheat Improvement Center","correspondingAuthor":false,"prefix":"","firstName":"João","middleName":"Vasco","lastName":"Silva","suffix":""},{"id":410209270,"identity":"78f4be82-6c34-4e35-b2b8-c80727e4824f","order_by":2,"name":"Latha Nagarajan","email":"","orcid":"","institution":"International Fertilizer Development Center","correspondingAuthor":false,"prefix":"","firstName":"Latha","middleName":"","lastName":"Nagarajan","suffix":""},{"id":410209271,"identity":"e6ec9641-ee73-4e4e-8131-c70b3e1659a0","order_by":3,"name":"Upendra Singh","email":"","orcid":"","institution":"International Fertilizer Development Center","correspondingAuthor":false,"prefix":"","firstName":"Upendra","middleName":"","lastName":"Singh","suffix":""}],"badges":[],"createdAt":"2025-01-29 08:08:25","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-5922699/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5922699/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":75285911,"identity":"54f7d234-7f65-401f-b2a6-426a41d7b982","added_by":"auto","created_at":"2025-02-03 04:34:48","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":514333,"visible":true,"origin":"","legend":"\u003cp\u003eRainfall anomaly across selected countries of Southern Africa (Zambia, Zimbabwe, Malawi, and Mozambique) during the 2023-2024 cropping season (a) and measured rainfall data in the study sites in Buzi District, Central Mozambique (b). Panel (a) displays the anomaly in total rainfall between November and April (cropping season period), quantified as the difference between the 2023-2024 cropping season rainfall and the long-term average cropping season rainfall (1981-2023). See Supplementary Fig. 1 for further details. Data were obtained from Funk et al. (2016). Panel (b) displays measured rainfall data in two sites of Buzi District, Bandua and Inharongue, during the 2022-2023 and 2023-2024 cropping seasons\u003c/p\u003e","description":"","filename":"Fig.1.png","url":"https://assets-eu.researchsquare.com/files/rs-5922699/v1/192a302062f12432429b5adb.png"},{"id":75285912,"identity":"276bd2b7-52f8-4777-9f7f-636e5a56b246","added_by":"auto","created_at":"2025-02-03 04:34:48","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":677651,"visible":true,"origin":"","legend":"\u003cp\u003eMaize yield response to variety, sowing date, ad fertilizer regime in fertile and infertile fields of Buzi district, Central Mozambique, during the 2022-2023 and 2023-2024 cropping seasons. The effect of sowing date could not be assessed in 2023-2024 cropping season due to dry spells at the time of planting. In the 2022-2023 cropping season, only researcher-managed experiments were carried out. In the 2023-2024 cropping season, the researcher-managed experiments were complemented with farmer-managed experiments conducted in the vicinity of the former. Note different y-axis values in (c). V1 and V2 refer to the early-maturity and the medium-maturity hybrid maize varieties, respectively, F0 to treatments without addition of mineral fertilizer, and F1 to treatments with addition of mineral fertilizer\u003c/p\u003e","description":"","filename":"Fig.2.png","url":"https://assets-eu.researchsquare.com/files/rs-5922699/v1/fdbd6eee95b7c859b9e663a2.png"},{"id":75285914,"identity":"f9d81bac-5aba-4260-b3cb-9504016a2bcc","added_by":"auto","created_at":"2025-02-03 04:34:48","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":1151504,"visible":true,"origin":"","legend":"\u003cp\u003eVariation in maize yield response to variety, sowing date, and fertilizer regime in Buzi district, Central Mozambique, during the 2022-2023 (year 1) and 2023-2024 (year 2) cropping seasons in fertile and infertile fields. The effect of sowing date could not be assessed in the 2023-2024 cropping season due to dry spells at the time of sowing. In the 2022-2023 cropping season, only researcher-managed (RM) experiments were carried out. In the 2023-2024 cropping season, the researcher-managed experiments were complemented with farmer-managed (FM) experiments conducted in the vicinity of the former. Maize yield response to variety was computed as the yield difference between the medium maturity variety (DK777 in both years) and the early maturity variety (DKC-80-33 in year 1 and MH43A in year 2). Maize yield response to sowing date was computed as the yield difference between the two later sowing dates (S2 and S3) and the early sowing date (S1). Maize yield response to fertilizer was computed as the yield difference between the fertilized treatments (F1) and the unfertilized treatments (F0). Data on the yield response in relative terms are provided in the Fig. S2\u003c/p\u003e","description":"","filename":"Fig.3.png","url":"https://assets-eu.researchsquare.com/files/rs-5922699/v1/6d84bb061f31c87d5b8cf014.png"},{"id":75285922,"identity":"df749fe7-678e-40d8-853f-ec379790b97d","added_by":"auto","created_at":"2025-02-03 04:34:48","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":525038,"visible":true,"origin":"","legend":"\u003cp\u003eVariation in plant population at harvest across early (MH43A) and medium (DK777) maturity varieties (a) and maize yield responses to plant population at harvest (b) in researcher- and farmer-managed experiments during the 2023-2024 cropping season. The solid and dashed black lines in (b) display quantile regressions fitted to 95\u003csup\u003eth\u003c/sup\u003e and 90\u003csup\u003eth\u003c/sup\u003e quantiles. Vertical lines in (b) indicate the average plant population at harvest whereas horizontal lines indicate the average maize yield in the researcher- and farmer-managed experiments\u003c/p\u003e","description":"","filename":"Fig.4.png","url":"https://assets-eu.researchsquare.com/files/rs-5922699/v1/dc6bf7c6959de78db01feba2.png"},{"id":75285918,"identity":"10d92565-ba61-429a-9e8f-40ad88d65915","added_by":"auto","created_at":"2025-02-03 04:34:48","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":704069,"visible":true,"origin":"","legend":"\u003cp\u003eProfitability and return on investment of early (V1) and medium (V2) maturity varieties with (F1) and without (F0) addition of mineral fertilizers in researcher- and farmer-managed experiments conducted in Buzi, central Mozambique during the 2022-2023 and 2023-2024 cropping seasons. Data are disaggregated across fertile and infertile fields. The horizontal red lines indicate no profit and return on investment equal to 1 (gross returns equal to input costs)\u003c/p\u003e","description":"","filename":"Fig.5.png","url":"https://assets-eu.researchsquare.com/files/rs-5922699/v1/99cc7e44392a80115d81ceae.png"},{"id":84074899,"identity":"16309b58-8d1d-40ba-bb99-9191be388530","added_by":"auto","created_at":"2025-06-06 13:02:02","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":5908305,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5922699/v1/89979b90-743c-4ca4-b7db-503520cc9699.pdf"},{"id":75285913,"identity":"60a55403-d258-4306-b76f-b9a3da436650","added_by":"auto","created_at":"2025-02-03 04:34:48","extension":"png","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":618243,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFig. S1 \u003c/strong\u003eAverage November to April (cropping season) rainfall over the period 1981-2023 in southern Africa (a) and cropping season rainfall between November 2023 and April 2024 (b). Data were obtained from Funk et al. (2016)\u003c/p\u003e","description":"","filename":"Fig.S1.png","url":"https://assets-eu.researchsquare.com/files/rs-5922699/v1/41d58cffaba8b1e5f9d88d45.png"},{"id":75285915,"identity":"1e28b86c-1efa-44bc-9f83-dda9a84d20cf","added_by":"auto","created_at":"2025-02-03 04:34:48","extension":"png","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":578597,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFig. S2 \u003c/strong\u003eVariation in maize yield response to variety, sowing date, and fertilizer regime in Buzi district, Central Mozambique, during the 2022-2023 (year 1) and 2023-2024 (year 2) cropping seasons in fertile and infertile fields. The effect of sowing date could not be assessed in the 2023-2024 cropping season due to dry spells at the time of planting. In the 2022-2023 cropping season, only researcher-managed (RM) experiments were carried out. In the 2023-2024 cropping season, the researcher-managed experiments were complemented with farmer-managed (FM) experiments conducted in the vicinity of the former. Maize yield response to variety (a) was computed as the yield difference between the medium-duration variety (DK777 in both years) and the early-duration variety (DKC80-33 in year 1 and MH43A in year 2) divided by the yield of the early-duration variety in the respective treatments. Maize yield response to sowing date (b) was computed as the yield difference between the two later sowing dates (S2 and S3) and the early sowing date (S1) divided by the yield in the respective S1 treatment in year 1 only. Maize yield response to fertilizer (c) was computed as the yield difference between the fertilized treatments (F1) and the unfertilized treatments (F0) divided by the yield in the respective unfertilized treatment\u003c/p\u003e","description":"","filename":"Fig.S2.png","url":"https://assets-eu.researchsquare.com/files/rs-5922699/v1/f1bf729ab636b1a4370c4133.png"}],"financialInterests":"No competing interests reported.","formattedTitle":"Unraveling the contribution of G x E x M interactions to maize productivity in Central Mozambique amid climate change","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eAgriculture is the main source of livelihood for smallholder farmers in sub-Saharan Africa. Yet, the region has the lowest agricultural productivity worldwide (Giller et al. \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). For maize, the most important cereal staple in the region, smallholders typically produce about 20% of what is biophysically possible with agronomic best practices (Assefa et al. \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Silva et al. \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2023a\u003c/span\u003e; van Ittersum et al. \u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e2016\u003c/span\u003e). Such a large yield gap, i.e., the difference between the water-limited potential yield and the actual farm yield under rainfed conditions (van Ittersum et al. \u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e2016\u003c/span\u003e), is the result of multiple agronomic and biophysical constraints. Poor agronomy is associated with suboptimal crop stands (Nyagumbo et al. \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2024\u003c/span\u003e), late planting and weeding (Leonardo et al. \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2015\u003c/span\u003e), and declining soil fertility due to continuous cultivation with limited external fertilizer inputs (Bekunda et al. \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2010\u003c/span\u003e; Tittonell and Giller \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2013\u003c/span\u003e). Climate variability and change, particularly erratic rainfall, further exacerbate the risks of rainfed crop production (Cairns et al. \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2021\u003c/span\u003e), often compromising the return on investment in fertilizer (Bonilla-Cedrez et al. \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2021\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eSustainable crop intensification is required to meet the future food demand in sub-Saharan Africa (Jayne and Sanchez \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Vanlauwe and Dobermann \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). Crop yields are the result of genotype-by-environment-by-management (G \u0026times; E \u0026times; M) interactions (Evans and Fischer \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e1999\u003c/span\u003e,; Fischer \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). Varieties of maize with improved genetics that have been adapted to the current climate are available to smallholders in the region (Cairns et al. \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2021\u003c/span\u003e) and are often adopted with positive impacts on maize productivity and farmers\u0026rsquo; livelihoods (Ngoma et al. under review; Evenson and Gollin \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2003\u003c/span\u003e). While climate change is projected to have a negative impact on cereal production across the region (Haile et al. \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Cairns et al. \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2013\u003c/span\u003e), such effects can be partially offset with existing cultivars (Alimagham et al. \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). Climate change impacts on crop production will depend on the soil fertility status and agronomic management, which can be influenced by farmers at the start of and throughout the growing season. For instance, Descheemaeker et al. (\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2020\u003c/span\u003e) found that soil fertility is as important as climate change in explaining future farm performance in Southern Zimbabwe. Therefore, disentangling the relative importance of G x E x M interactions on crop yield is key in identifying opportunities for sustainable crop intensification attuned to local conditions.\u003c/p\u003e \u003cp\u003eAccording to the Global Climate Risk Index 2021, Mozambique is the country most affected by and least prepared for climate change (Eckstein et al. \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Droughts, floods, and cyclones occur with increasing frequency in the country, leading to devastating outcomes for insufficiently prepared farmers who rely on rainfed agriculture. Agriculture is dominated by small-scale farmers (about 98%) who primarily produce for their own consumption (MADER \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). About 10% use improved seeds, 8% use inorganic fertilizers, 7% have access to extension services, and less than 1% have access to agricultural credit (\u003cem\u003eibid\u003c/em\u003e). In Mozambique, a country with relatively abundant land, maize is the most important food and cash crop for smallholders, cultivated on nearly 40% of all cropland under smallholder agriculture (\u003cem\u003eibid\u003c/em\u003e). Yet, it is also the crop most vulnerable to climate variability, exposing smallholders to food insecurity. Past increases in maize production in the country were achieved through cropland expansion (Leonardo et al. \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2018\u003c/span\u003e) rather than productivity increases on existing cropland. However, increasing production through cropland expansion is limited by labor availability (Baudron et al. \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2012a\u003c/span\u003e; Leonardo et al. \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2018\u003c/span\u003e) and associated with greenhouse gas emissions and biodiversity loss (Beyer et al. \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Increasing crop production per unit area through increases in fertilizer use and adoption of improved crop varieties and good agronomic practices will be required to curb land conversion to agriculture and achieve self-sufficiency of maize at the national level.\u003c/p\u003e \u003cp\u003eThe objectives of this study were twofold: (1) disentangle the relative contribution of G x E x M interactions to smallholder maize yields in Central Mozambique and (2) explore options for sustainable intensification of maize production amid soil fertility and rainfall variability. Researcher- and farmer-managed on-farm experiments were established in fields with varying soil fertility statuses to assess how different maize varieties respond to changes in sowing date and fertilizer regime over two cropping seasons. The experiments were conducted in Buzi District, a region severely affected by recent extreme weather events, such as Cyclone Idai in 2019, Tropical Storm Chalane in 2020, Cyclone Eloise in 2021 (Crawford et al. \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Mashula et al. \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Speight et al. \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e2023\u003c/span\u003e), and the 2024 El Ni\u0026ntilde;o-induced drought (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea). We hypothesized that maize yield response to improved varieties and sowing date is conditional on nutrient availability, which remains the most limiting factor to maize yields in the study area. This study contextualizes the benefits of improved agronomic practices and improved plant genetics for smallholder maize production under climate change.\u003c/p\u003e"},{"header":"2. Material and methods","content":"\u003cp\u003e\u003cem\u003e2.1 Site selection and characteristics\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eResearcher-managed experiments were conducted on-farm in two consecutive cropping seasons (2022-2023 and 2023-2024) in Buzi District, Central Mozambique. The study area lies within 19\u0026deg;55\u0026apos;53.1\u0026quot;S, 34\u0026deg;25\u0026apos;46.3\u0026quot;E in Bandua and 19\u0026deg;56\u0026apos;56.7\u0026quot;S, 34\u0026deg;32\u0026apos;50.6\u0026quot;E in Inharongue. These sites were selected due to their importance for maize production, diversity of soil types, and high frequency of extreme weather events. The main soil types found in the study area are Mollic Fluvisols and Eutric Fluvisols. The district has a tropical humid climate, with a hot, wet season from November to March and a cool, dry season from April to October. The unimodal rainfall pattern allows for only one cropping season (wet season) per year. The rainfall anomaly (i.e., the difference between the 2023-2024 cropping season rainfall and the 30-year average growing rainfall) across Southern Africa is displayed in Fig. 1a and Fig. S1. Rainfall measured in the study sites during both cropping seasons is displayed in Fig. 1b.\u003c/p\u003e\n\u003cp\u003eHeterogeneity in soil fertility status is a common feature of smallholder agriculture. Recognizing this diversity is important for targeting appropriate soil fertility management practices (Tittonell et al. 2005). Four focus group discussions with farmers, with six men and six women participating in each, were organized to identify the most common soil types for the researcher-managed experiments. Based on soil water-holding capacity, soil texture, and farmers\u0026rsquo; experience in cultivating maize on their fields, two types of soil were identified and classified by farmers as having high and low soil fertility, categorized \u0026nbsp;as fertile fields and infertile fields, respectively. In the 2022-2023 cropping season, four experiments (two in fertile fields and two in infertile fields) were established and managed by agronomists. In the 2023-2024 cropping season, the number of fields managed by agronomists was increased to five (one in a fertile field and four in infertile fields). Farmers strongly prefer fertile fields; therefore, in the second season, we failed to find any farmers who were willing to use their fertile land for the experiment. An additional 33 farmer-managed experiments (four in fertile fields and 29 in infertile fields) were conducted in the second cropping season to capture variability in the response to the tested treatments across a wider range of soil and management conditions. The experimental design was the same as in the researcher-managed experiments. Apart from fertilizer application, all farming activities in these fields, i.e., sowing, weeding, and harvesting, were performed by the farm household. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e2.2 Experimental design, treatments, and crop management \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eResearcher- and farmer-managed experiments were designed as a randomized complete block. The main factor evaluated was sowing date, which included three times: early sowing in November, intermediate sowing in December, and late sowing in January. In the 2023‑2024 cropping season, only one sowing date was possible due to the severe drought and early cessation of rainfall caused by El Ni\u0026ntilde;o (Fig. 1). The second factor evaluated was maize variety: a short-duration hybrid variety with 110-115 days between sowing and maturity (DKC-80-33 in the 2022-2023 cropping season and MH43A in the 2023-2024 cropping season) and a medium-duration hybrid variety with 115-130 days between sowing and maturity (DK777 in both cropping seasons). Different early-duration varieties were used in the two cropping seasons because farmers were not interested in cultivating DKC-80-33 in the second season due to its poor storability. The third factor evaluated was fertilizer regime, either with or without mineral fertilizer application. The source of nutrients used in the experiment was the commonly available fertilizer blend NPK 23:10:5+6S+1Zn applied basally at a rate of 125 kg ha\u003csup\u003e-1\u003c/sup\u003e. Urea (46% N) was applied at knee-high stage, depending on moisture availability, at the same rate as the basal application. This translates to a total of 86.3 kg N ha\u003csup\u003e-1\u003c/sup\u003e, 22.9 kg P\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u003c/sub\u003e ha\u003csup\u003e-1\u003c/sup\u003e, and 6 kg K\u003csub\u003e2\u003c/sub\u003eO ha\u003csup\u003e-1\u003c/sup\u003e. Such design allowed us to elucidate the relative contribution of G \u0026times; E \u0026times; M interactions, since the sowing dates reflect different E \u0026times; M interactions on maize yield, the two varieties reflect the contribution of G on maize yield, and the two fertilizer regimes reflect the contribution of M on maize yield. Cropping season and soil fertility status are other important components of E considered in our experimental setup.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe area of cultivation for each sowing date consisted of five blocks, each with four plots of 5 m \u0026times; 8 m, and five replications per treatment and per sowing date. Maize was planted at a spacing of 0.75 m \u0026times; 0.50 m, with two plants per station, targeting a plant population at sowing of 53,333 plants ha\u003csup\u003e-1\u003c/sup\u003e. On researcher-managed experiments, land preparation (plowing and harrowing) was done with a tractor, allowing the incorporation of crop residues from the previous cropping season. To avoid the residual effects of fertilizers, new adjacent fields were selected in the second cropping season. On farmer-managed experiments, most land preparation was done manually or using oxen. For all experiments, maize was the previous crop. Sowing, fertilizer application, and weeding were done manually in all experiments. No irrigation was supplied, and the first sowing date was determined by the soil moisture content. Rainfall was measured daily using a rain gauge from the time of planting to harvesting at each site and recorded by the field technician and lead farmers. During the growing season, the crop was treated with commercial pesticides to control fall armyworm when the risk of infestation existed. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e2.3 Soil analysis, maize grain yield, and plant population\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eSoil samples were collected following a zig-zag pattern within each field prior to sowing and fertilizer application. A total of eight samples were taken using a soil auger at 0-20 cm and 20-40 cm depths. An air-dried sub-sample of about 0.5 kg from each depth was analyzed at Crop Nutrition Laboratory Services in Nairobi, Kenya. The sub-samples were oven-dried, passed through a 2 mm sieve, and analyzed for pH (H\u003csub\u003e2\u003c/sub\u003eO) following the potentiometric method; available P, exchangeable K\u003csup\u003e+\u003c/sup\u003e, Ca\u003csup\u003e2+\u003c/sup\u003e, Mg\u003csup\u003e2+\u003c/sup\u003e, Na\u003csup\u003e+\u003c/sup\u003e, Zn\u003csup\u003e2+\u003c/sup\u003e, Mn\u003csup\u003e2+\u003c/sup\u003e, Cu\u003csup\u003e2+\u003c/sup\u003e, S, and B following the Mehlich-3 inductively coupled plasma (ICP); exchangeable aluminum following the colorimetric method; total N following the Kjeldahl method; soil organic carbon (dry combustion); and texture following the hydrometer method. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAt maturity, the two middle rows of each treatment plot were harvested, leaving two plants at each end of the row (net harvest area). All plants in the net harvest area of each plot were cut at surface level, and the total aboveground biomass (stems, leaves, and cobs) was weighed. A subsample of 10 plants was randomly taken from the harvested plants and weighed. If the yield was poor, as in the second cropping season on infertile fields, all biomass from the net harvest area was considered for the final measurement. The cobs from subsamples or the net harvest area were separated from the plants, and both weights were taken separately. Then, cobs and stalks (stems and leaves) were air-dried for about two weeks, threshed, and weighed, and the moisture content was determined with a grain moisture meter. Grain yields were adjusted to a moisture content of 12 %, as follows:\u003c/p\u003e\n\u003cp\u003eGrain yield (at 12 % grain moisture) = grain yield fresh * (100 \u0026ndash; fresh grain moisture %) / 88 %\u003c/p\u003e\n\u003cp\u003eThe maize plant population was determined at harvest by counting the number of plants in each net harvest area. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e2.4 Economic assessment\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eAn economic assessment of the treatments tested in the researcher-managed experiments in the two cropping seasons and in the farmer-managed experiments in the 2023-2024 cropping season was conducted based on the profit and returns on investment associated with capital inputs (i.e., seed and fertilizer). Profit (USD ha\u003csup\u003e-1\u003c/sup\u003e) was calculated as the difference between gross return and input costs. Return on investment (USD USD\u003csup\u003e-1\u003c/sup\u003e) was calculated as the ratio between gross return and input costs. Gross return was calculated by multiplying the maize yield in each treatment by the market price of maize, USD 0.22 kg\u003csup\u003e-1\u003c/sup\u003e, regardless of variety type. The price of maize was estimated as the average of three farm-gate prices in the study region: the price at harvest (April to July), during the intermediary period (August to November), and during the lean period (December to March). Input costs were calculated as the sum of seed costs and fertilizer costs. Seed costs were calculated by multiplying the amount of seed used for each treatment by the price of the seed: USD 3.3 kg\u003csup\u003e-1\u003c/sup\u003e for the early-duration variety DKC-80-33 (seed amount equal to 23.3 kg ha\u003csup\u003e-1\u003c/sup\u003e), USD 2.4 kg\u003csup\u003e-1\u003c/sup\u003e for the early-duration variety MH43A (12.5 kg ha\u003csup\u003e-1\u003c/sup\u003e), and USD 3.3 kg\u003csup\u003e-1\u003c/sup\u003e for the medium-duration variety DK777 (14.8 kg ha\u003csup\u003e-1\u003c/sup\u003e). Fertilizer cost was calculated by multiplying the amount of urea and NPKSZn fertilizer used in each treatment by the respective market price in the study region, USD 45 per 50-kg bag for both fertilizer types. Seed and fertilizer costs for each variety and fertilizer type were obtained from local agro-dealers in the study region. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e2.5 Data analysis\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eStatistical analyses were conducted using linear mixed models fitted to different subsets of the data. Treatment effects on maize grain yield were assessed separately for researcher-managed experiments conducted in fertile and infertile fields in each cropping season and for farmer-managed experiments conducted in fertile and infertile fields in the 2023-2024 cropping season. The analyses were done separately for these different subsets of data due to large differences in rainfall between the two cropping seasons (Fig. 1), which compromised the second and third sowing in the 2023-2024 cropping season, resulting in unbalanced data, and due to differences in indigenous soil fertility (fertile vs. infertile fields; Table 1) and trial management (researcher vs. farmer management).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe linear mixed models fitted for researcher-managed experiments in fertile and infertile fields conducted in the 2022-2023 cropping season tested a three-way interaction between the fixed effects: variety type, sowing time, and fertilizer regime. For the researcher- and farmer-managed experiments conducted in the 2023-2024 cropping season, the fitted linear mixed models tested a two-way interaction between the fixed effects: variety type and fertilizer regime. All models considered the replicate within each farm (i.e., its identifier) as a random effect, except in the case of fertile fields in the 2023-2024 cropping season, where only replication was considered as a random effect since only one farm hosted the researcher-managed experiment on a fertile field during this cropping season. Linear mixed models were fitted with restricted maximum likelihood using the lmer() function of the lmerTest R package (Kuznetsova et al. 2017). The statistical significance of the fixed effects and their interaction on maize yield were tested using analysis of variance (ANOVA) with the anova() function of R. Least-square means were then predicted using the fitted models for each variety type x sowing time x fertilizer regime combination using the emmeans() function of the emmeans R package (Lenth, 2024). The same linear mixed model approach was used to test for treatment effects on profit and return on investment.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eVariability in maize yield response to variety type, sowing time, and fertilizer regime was assessed using cumulative distribution curves (Vanlauwe et al. 2019), computed for each factor independently and for each cropping season x management type (researcher vs. farmer management) combination in both fertile and infertile fields. Cumulative distribution curves provide a measure of the risk associated with each of the factors tested and indicate the likelihood of obtaining any given outcome within the range of outcomes captured in the data. Cumulative distribution curves were developed for absolute maize yield response (i.e., the difference between treatment and control yields) and for relative maize yield response (i.e., the absolute maize yield response relative to the control yield). The early-duration variety, the first sowing date, and no fertilizer use were considered as controls when assessing maize yield response to variety type, sowing time, and fertilizer regime, respectively. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003eData on the maize plant population at harvest were only collected for the experiments conducted in the 2023-2024 cropping season. Linear mixed models were fitted to assess the effect of variety type and fertilizer regime (two-way interaction) on the maize plant population at harvest on either fertile or infertile fields. The two-way interaction and the fertilizer regime had no statistically significant effect on plant population at harvest in either of the fitted models; hence, data on plant population at harvest were presented for different variety types only. Finally, maize yield response to plant population at harvest was assessed using boundary line functions that depict the maximum maize yield for a given plant population at harvest. As such, input-output combinations that define the boundary function are limited by plant population at harvest, whereas input-output combinations below the boundary function are limited by other factors beyond plant population at harvest. Boundary lines were estimated for the pooled data with quantile regressions fitted to the 90\u003csup\u003eth\u003c/sup\u003e and 95\u003csup\u003eth\u003c/sup\u003e quantiles using the rq() function of the quantreg R package (Koenker 2024).\u003c/p\u003e"},{"header":"3. Results","content":"\u003cp\u003e\u003cem\u003e3.1 Soil fertility status\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThe farmers\u0026rsquo; classification of fertile and infertile fields was mostly based on the clay content and buffering capacity among the analyzed soil properties, especially in the subsoil (Table 1). Soil texture was dominated by clay in fertile fields and clay loam to sandy clay loam in infertile fields. The mean measured pH (H\u003csub\u003e2\u003c/sub\u003eO) of the topsoil and subsoil of both fertile and infertile fields ranged from 6.0 to 6.2, which can be classified as optimum for maize crops. Soil organic carbon was also at adequate levels for maize production at 19-24 g kg\u003csup\u003e-1\u003c/sup\u003e, while total nitrogen was low, ranging between 1.1 g kg\u003csup\u003e-1\u003c/sup\u003e and 1.4 g kg\u003csup\u003e-1\u003c/sup\u003e. Phosphorus was at optimum levels for maize crops, between 64.7 mg kg\u003csup\u003e-1\u003c/sup\u003e and 90.4 mg kg\u003csup\u003e-1\u003c/sup\u003e, whereas potassium was low in the topsoil and the subsoil of both field types, between 139 mg kg\u003csup\u003e-1\u003c/sup\u003e and 242 mg kg\u003csup\u003e-1\u003c/sup\u003e. Sulfur, magnesium, and zinc were at optimum level in topsoil and subsoil regardless of field type. Boron and calcium were low in the topsoil and the subsoil of both fertile and infertile fields.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTable 1\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003ePhysical and chemical soil characteristics from the researcher-managed experiments for the 0- 20 and 20-40 cm depth. Soil samples were taken prior to the establishment of the treatments in the 2022-2023 growing season. Exch.Al = exchangeable aluminium; ECEC = effective cation exchange capacity by summation.\u003c/p\u003e\n\u003cdiv align=\"\"\u003e\n \u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"630\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 15px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 33px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTopsoil (0-20 cm)\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 3px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"bottom\" style=\"width: 34px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSubsoil (20-40 cm)\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 15px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"bottom\" style=\"width: 33px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eFarmers\u0026rsquo; classification\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 3px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 34px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eFarmers\u0026rsquo; classification\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 15px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eProperties\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eUnits\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 16px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eFertile\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eInfertile\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 3px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eFertile\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eInfertile\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"7\" valign=\"bottom\" style=\"width: 100px;\"\u003e\n \u003cp\u003e\u003cem\u003eParticle size distribution\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 15px;\"\u003e\n \u003cp\u003eSand\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 16px;\"\u003e\n \u003cp\u003e30.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e36.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 3px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e28.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e45.6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 15px;\"\u003e\n \u003cp\u003eSilt\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 16px;\"\u003e\n \u003cp\u003e27.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e27.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 3px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e28.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e23.1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 15px;\"\u003e\n \u003cp\u003eClay\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 16px;\"\u003e\n \u003cp\u003e42.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e36.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 3px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e43.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e31.3\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 15px;\"\u003e\n \u003cp\u003eSoil texture\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 16px;\"\u003e\n \u003cp\u003eClay\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003eClay loam\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 3px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003eClay\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003eSand clay loam\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"7\" valign=\"bottom\" style=\"width: 100px;\"\u003e\n \u003cp\u003e\u003cem\u003eSoil C and nutrients\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 15px;\"\u003e\n \u003cp\u003eCarbon\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003eg kg\u003csup\u003e-1\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 16px;\"\u003e\n \u003cp\u003e22.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e22.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 3px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e24.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e18.7\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 15px;\"\u003e\n \u003cp\u003eNitrogen\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003eg kg\u003csup\u003e-1\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 16px;\"\u003e\n \u003cp\u003e1.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e1.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 3px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e1.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e1.1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 15px;\"\u003e\n \u003cp\u003ePhosphorus\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003emg kg\u003csup\u003e-1\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 16px;\"\u003e\n \u003cp\u003e83.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e84.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 3px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e90.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e64.7\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 15px;\"\u003e\n \u003cp\u003eSulphur\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003emg kg\u003csup\u003e-1\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 16px;\"\u003e\n \u003cp\u003e10.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e10.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 3px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e11.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e8.9\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 15px;\"\u003e\n \u003cp\u003eManganese\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003emg kg\u003csup\u003e-1\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 16px;\"\u003e\n \u003cp\u003e83.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e75.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 3px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e84.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e71.1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 15px;\"\u003e\n \u003cp\u003eBoron\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003emg kg\u003csup\u003e-1\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 16px;\"\u003e\n \u003cp\u003e0.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 3px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.5\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 15px;\"\u003e\n \u003cp\u003eZinc\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003emg kg\u003csup\u003e-1\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 16px;\"\u003e\n \u003cp\u003e4.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e4.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 3px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e4.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e2.9\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"7\" valign=\"bottom\" style=\"width: 100px;\"\u003e\n \u003cp\u003e\u003cem\u003eSoil acidity\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 15px;\"\u003e\n \u003cp\u003epH in water\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 16px;\"\u003e\n \u003cp\u003e6.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e6.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 3px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e6.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e6.2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 15px;\"\u003e\n \u003cp\u003eExch.Al\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003emeq 100g\u003csup\u003e-1\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 16px;\"\u003e\n \u003cp\u003e\u0026lt;0.10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e\u0026lt;0.10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 3px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e\u0026lt;0.10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e\u0026lt;0.10\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"7\" valign=\"bottom\" style=\"width: 100px;\"\u003e\n \u003cp\u003e\u003cem\u003eBuffering capacity\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 15px;\"\u003e\n \u003cp\u003eCalcium\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003emeq 100g\u003csup\u003e-1\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 16px;\"\u003e\n \u003cp\u003e19.12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e16.86\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 3px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e19.09\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e14.89\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 15px;\"\u003e\n \u003cp\u003eMagnesium\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003emeq 100g\u003csup\u003e-1\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 16px;\"\u003e\n \u003cp\u003e0.70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.63\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 3px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.71\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.59\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 15px;\"\u003e\n \u003cp\u003ePotassium\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003emeq 100g\u003csup\u003e-1\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 16px;\"\u003e\n \u003cp\u003e0.62\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.53\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 3px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.57\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.36\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 15px;\"\u003e\n \u003cp\u003eSodium\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003emeq 100g\u003csup\u003e-1\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 16px;\"\u003e\n \u003cp\u003e0.23\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 3px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.23\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e0.19\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 15px;\"\u003e\n \u003cp\u003eECEC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 13px;\"\u003e\n \u003cp\u003emeq 100g\u003csup\u003e-1\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 16px;\"\u003e\n \u003cp\u003e20.66\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e18.21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 3px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e20.59\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 17px;\"\u003e\n \u003cp\u003e16.03\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u003cem\u003e3.2 Maize yield response to variety type, sowing date, and fertilizer regime\u0026nbsp;\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eIn the 2022-2023 cropping season, a significant three-way interaction was observed between fertilizer regime, sowing date, and variety type for maize yield on researcher-managed experiments in fertile fields (\u003cem\u003ep\u003c/em\u003e \u0026lt; 0.01) (Table 2). The highest maize yields on these fields were obtained with early sowing of a medium- (3.6 t ha\u003csup\u003e-1\u003c/sup\u003e) or early- (3.1 t ha\u003csup\u003e-1\u003c/sup\u003e) duration maize variety with fertilizer applied (Fig. 2a). Conversely, late sowing without fertilizer yielded the least on these fields regardless of variety type (about 1.6 t ha\u003csup\u003e-1\u003c/sup\u003e on average). No interactions between sowing date and variety type or between variety type and fertilizer regime were observed for this cropping season on researcher-managed experiments in infertile fields (Table 2). Yet, the effect of fertilizer regime was highly significant in these fields (\u003cem\u003ep\u003c/em\u003e \u0026lt; 0.001), with fertilized treatments yielding an average of 2.1 t ha\u003csup\u003e-1\u003c/sup\u003e, compared with 1.4 t ha\u003csup\u003e-1\u003c/sup\u003e obtained in the unfertilized treatments (Fig. 2b). Maize yields were 23% greater on researcher-managed experiments in fertile fields than infertile fields, showing the importance of soil fertility status on maize productivity and response to agronomic management practices.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2\u0026nbsp;\u003c/strong\u003eAnalysis of variance regarding the effects of variety, sowing date, and fertilizer regime on maize yield in Buzi district, Central Mozambique. Researcher managed experiments were conducted in the 2022-2023 and 2023-2024 cropping seasons. The same experiment was also conducted under farmer management in the latter cropping season. The effect of sowing date could not be assessed in 2023-2024 due to dry spells at the time of sowing\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" align=\"\" width=\"674\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 81px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eField type\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 183px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTreatment\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 72px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSum Sq.\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 77px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMean Sq.\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 62px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNumDF\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 57px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eDenDF\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 67px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eF-value\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"bottom\" style=\"width: 75px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ep-value\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"8\" valign=\"bottom\" style=\"width: 673px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eResearcher-managed experiments (2022-2023)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 81px;\"\u003e\n \u003cp\u003eFertile\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 183px;\"\u003e\n \u003cp\u003eSowing\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 72px;\"\u003e\n \u003cp\u003e13.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 77px;\"\u003e\n \u003cp\u003e6.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 62px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 57px;\"\u003e\n \u003cp\u003e99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 67px;\"\u003e\n \u003cp\u003e11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"bottom\" style=\"width: 75px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026lt;0.001\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 81px;\"\u003e\n \u003cp\u003eFertile\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 183px;\"\u003e\n \u003cp\u003eVariety\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 72px;\"\u003e\n \u003cp\u003e6.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 77px;\"\u003e\n \u003cp\u003e6.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 62px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 57px;\"\u003e\n \u003cp\u003e99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 67px;\"\u003e\n \u003cp\u003e9.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"bottom\" style=\"width: 75px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026lt;0.001\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 81px;\"\u003e\n \u003cp\u003eFertile\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 183px;\"\u003e\n \u003cp\u003eFertilizer\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 72px;\"\u003e\n \u003cp\u003e18.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 77px;\"\u003e\n \u003cp\u003e18.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 62px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 57px;\"\u003e\n \u003cp\u003e99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 67px;\"\u003e\n \u003cp\u003e29\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"bottom\" style=\"width: 75px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026lt;0.001\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 81px;\"\u003e\n \u003cp\u003eFertile\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 183px;\"\u003e\n \u003cp\u003eSowing x Variety\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 72px;\"\u003e\n \u003cp\u003e0.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 77px;\"\u003e\n \u003cp\u003e0.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 62px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 57px;\"\u003e\n \u003cp\u003e99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 67px;\"\u003e\n \u003cp\u003e0.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"bottom\" style=\"width: 75px;\"\u003e\n \u003cp\u003en.s.\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 81px;\"\u003e\n \u003cp\u003eFertile\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 183px;\"\u003e\n \u003cp\u003eSowing x Fertilizer\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 72px;\"\u003e\n \u003cp\u003e5.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 77px;\"\u003e\n \u003cp\u003e2.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 62px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 57px;\"\u003e\n \u003cp\u003e99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 67px;\"\u003e\n \u003cp\u003e4.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"bottom\" style=\"width: 75px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;0.020\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 81px;\"\u003e\n \u003cp\u003eFertile\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 183px;\"\u003e\n \u003cp\u003eVariety x Fertilizer\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 72px;\"\u003e\n \u003cp\u003e0.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 77px;\"\u003e\n \u003cp\u003e0.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 62px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 57px;\"\u003e\n \u003cp\u003e99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 67px;\"\u003e\n \u003cp\u003e0.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"bottom\" style=\"width: 75px;\"\u003e\n \u003cp\u003en.s.\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 81px;\"\u003e\n \u003cp\u003eFertile\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 183px;\"\u003e\n \u003cp\u003eSowing x Variety x Fertilizer\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 72px;\"\u003e\n \u003cp\u003e5.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 77px;\"\u003e\n \u003cp\u003e2.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 62px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 57px;\"\u003e\n \u003cp\u003e99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 67px;\"\u003e\n \u003cp\u003e4.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"bottom\" style=\"width: 75px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;0.010\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 81px;\"\u003e\n \u003cp\u003eInfertile\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 183px;\"\u003e\n \u003cp\u003eSowing\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 72px;\"\u003e\n \u003cp\u003e0.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 77px;\"\u003e\n \u003cp\u003e0.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 62px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 57px;\"\u003e\n \u003cp\u003e88\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 67px;\"\u003e\n \u003cp\u003e0.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"bottom\" style=\"width: 75px;\"\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 81px;\"\u003e\n \u003cp\u003eInfertile\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 183px;\"\u003e\n \u003cp\u003eVariety\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 72px;\"\u003e\n \u003cp\u003e0.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 77px;\"\u003e\n \u003cp\u003e0.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 62px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 57px;\"\u003e\n \u003cp\u003e88\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 67px;\"\u003e\n \u003cp\u003e0.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"bottom\" style=\"width: 75px;\"\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 81px;\"\u003e\n \u003cp\u003eInfertile\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 183px;\"\u003e\n \u003cp\u003eFertilizer\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 72px;\"\u003e\n \u003cp\u003e16.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 77px;\"\u003e\n \u003cp\u003e16.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 62px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 57px;\"\u003e\n \u003cp\u003e88\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 67px;\"\u003e\n \u003cp\u003e31.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"bottom\" style=\"width: 75px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026lt;0.001\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 81px;\"\u003e\n \u003cp\u003eInfertile\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 183px;\"\u003e\n \u003cp\u003eSowing x Variety\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 72px;\"\u003e\n \u003cp\u003e0.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 77px;\"\u003e\n \u003cp\u003e0.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 62px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 57px;\"\u003e\n \u003cp\u003e88\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 67px;\"\u003e\n \u003cp\u003e0.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"bottom\" style=\"width: 75px;\"\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 81px;\"\u003e\n \u003cp\u003eInfertile\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 183px;\"\u003e\n \u003cp\u003eSowing x Fertilizer\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 72px;\"\u003e\n \u003cp\u003e1.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 77px;\"\u003e\n \u003cp\u003e0.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 62px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 57px;\"\u003e\n \u003cp\u003e88\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 67px;\"\u003e\n \u003cp\u003e0.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"bottom\" style=\"width: 75px;\"\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 81px;\"\u003e\n \u003cp\u003eInfertile\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 183px;\"\u003e\n \u003cp\u003eVariety x Fertilizer\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 72px;\"\u003e\n \u003cp\u003e1.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 77px;\"\u003e\n \u003cp\u003e1.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 62px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 57px;\"\u003e\n \u003cp\u003e88\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 67px;\"\u003e\n \u003cp\u003e1.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"bottom\" style=\"width: 75px;\"\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 81px;\"\u003e\n \u003cp\u003eInfertile\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 183px;\"\u003e\n \u003cp\u003eSowing x Variety x Fertilizer\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 72px;\"\u003e\n \u003cp\u003e1.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 77px;\"\u003e\n \u003cp\u003e0.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 62px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 57px;\"\u003e\n \u003cp\u003e88\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 67px;\"\u003e\n \u003cp\u003e1.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"bottom\" style=\"width: 75px;\"\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"8\" valign=\"bottom\" style=\"width: 673px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eResearcher-managed experiments (2023-2024)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 81px;\"\u003e\n \u003cp\u003eFertile\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 183px;\"\u003e\n \u003cp\u003eVariety\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 72px;\"\u003e\n \u003cp\u003e1.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 77px;\"\u003e\n \u003cp\u003e1.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 62px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 57px;\"\u003e\n \u003cp\u003e9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 67px;\"\u003e\n \u003cp\u003e8.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"bottom\" style=\"width: 75px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.020\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 81px;\"\u003e\n \u003cp\u003eFertile\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 183px;\"\u003e\n \u003cp\u003eFertilizer\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 72px;\"\u003e\n \u003cp\u003e0.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 77px;\"\u003e\n \u003cp\u003e0.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 62px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 57px;\"\u003e\n \u003cp\u003e9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 67px;\"\u003e\n \u003cp\u003e0.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"bottom\" style=\"width: 75px;\"\u003e\n \u003cp\u003en.s\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 81px;\"\u003e\n \u003cp\u003eFertile\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 183px;\"\u003e\n \u003cp\u003eVariety x Fertilizer\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 72px;\"\u003e\n \u003cp\u003e0.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 77px;\"\u003e\n \u003cp\u003e0.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 62px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 57px;\"\u003e\n \u003cp\u003e9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 67px;\"\u003e\n \u003cp\u003e3.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"bottom\" style=\"width: 75px;\"\u003e\n \u003cp\u003en.s.\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 81px;\"\u003e\n \u003cp\u003eInfertile\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 183px;\"\u003e\n \u003cp\u003eVariety\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 72px;\"\u003e\n \u003cp\u003e0.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 77px;\"\u003e\n \u003cp\u003e0.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 62px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 57px;\"\u003e\n \u003cp\u003e53\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 67px;\"\u003e\n \u003cp\u003e3.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"bottom\" style=\"width: 75px;\"\u003e\n \u003cp\u003e0.060\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 81px;\"\u003e\n \u003cp\u003eInfertile\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 183px;\"\u003e\n \u003cp\u003eFertilizer\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 72px;\"\u003e\n \u003cp\u003e10.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 77px;\"\u003e\n \u003cp\u003e10.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 62px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 57px;\"\u003e\n \u003cp\u003e53\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 67px;\"\u003e\n \u003cp\u003e61.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"bottom\" style=\"width: 75px;\"\u003e\n \u003cp\u003e\u0026lt;\u003cstrong\u003e0.001\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 81px;\"\u003e\n \u003cp\u003eInfertile\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 183px;\"\u003e\n \u003cp\u003eVariety x Fertilizer\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 72px;\"\u003e\n \u003cp\u003e0.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 77px;\"\u003e\n \u003cp\u003e0.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 62px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 57px;\"\u003e\n \u003cp\u003e53\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 67px;\"\u003e\n \u003cp\u003e0.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"bottom\" style=\"width: 75px;\"\u003e\n \u003cp\u003en.s.\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"8\" valign=\"bottom\" style=\"width: 673px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eFarmer-managed experiments (2023-2024)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 1px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 81px;\"\u003e\n \u003cp\u003eFertile\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 183px;\"\u003e\n \u003cp\u003eVariety\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 72px;\"\u003e\n \u003cp\u003e2.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 77px;\"\u003e\n \u003cp\u003e2.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 62px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 57px;\"\u003e\n \u003cp\u003e45\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 67px;\"\u003e\n \u003cp\u003e13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"bottom\" style=\"width: 75px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026lt;0.001\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 81px;\"\u003e\n \u003cp\u003eFertile\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 183px;\"\u003e\n \u003cp\u003eFertilizer\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 72px;\"\u003e\n \u003cp\u003e5.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 77px;\"\u003e\n \u003cp\u003e5.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 62px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 57px;\"\u003e\n \u003cp\u003e45\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 67px;\"\u003e\n \u003cp\u003e30.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"bottom\" style=\"width: 75px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026lt;0.001\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 81px;\"\u003e\n \u003cp\u003eFertile\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 183px;\"\u003e\n \u003cp\u003eVariety x Fertilizer\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 72px;\"\u003e\n \u003cp\u003e0.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 77px;\"\u003e\n \u003cp\u003e0.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 62px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 57px;\"\u003e\n \u003cp\u003e45\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 67px;\"\u003e\n \u003cp\u003e0.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"bottom\" style=\"width: 75px;\"\u003e\n \u003cp\u003en.s.\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 81px;\"\u003e\n \u003cp\u003eInfertile\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 183px;\"\u003e\n \u003cp\u003eVariety\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 72px;\"\u003e\n \u003cp\u003e6.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 77px;\"\u003e\n \u003cp\u003e6.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 62px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 57px;\"\u003e\n \u003cp\u003e345\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 67px;\"\u003e\n \u003cp\u003e55\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"bottom\" style=\"width: 75px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026lt;0.001\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 81px;\"\u003e\n \u003cp\u003eInfertile\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 183px;\"\u003e\n \u003cp\u003eFertilizer\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 72px;\"\u003e\n \u003cp\u003e10.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 77px;\"\u003e\n \u003cp\u003e10.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 62px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 57px;\"\u003e\n \u003cp\u003e345\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 67px;\"\u003e\n \u003cp\u003e82.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"bottom\" style=\"width: 75px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026lt;0.001\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 81px;\"\u003e\n \u003cp\u003eInfertile\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 183px;\"\u003e\n \u003cp\u003eVariety x Fertilizer\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 72px;\"\u003e\n \u003cp\u003e0.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 77px;\"\u003e\n \u003cp\u003e0.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 62px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 57px;\"\u003e\n \u003cp\u003e345\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 67px;\"\u003e\n \u003cp\u003e1.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"bottom\" style=\"width: 75px;\"\u003e\n \u003cp\u003en.s.\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eIn the 2023-2024 cropping season, significant yield differences (\u003cem\u003ep\u003c/em\u003e = 0.02) were observed between early- and medium-duration varieties on researcher-managed experiments in fertile fields (Table 2). Maize yield was an average of 3.3 t ha\u003csup\u003e-1\u003c/sup\u003e with the early-duration variety and 4.0 t ha\u003csup\u003e-1\u003c/sup\u003e with the medium-duration variety on in these fields (Fig. 2c). Conversely, significant yield differences (\u003cem\u003ep\u003c/em\u003e \u0026lt; 0.001) were observed between fertilizer regimes on researcher-managed experiments in infertile fields (Table 2). In these fields, maize yield was an average of 1.3 t ha\u003csup\u003e-1\u003c/sup\u003e with fertilizer and 0.4 t ha\u003csup\u003e-1\u003c/sup\u003e without fertilizer (Fig. 2d), substantiating the results of the 2022-2023 cropping season. Maize yield in the farmer-managed experiments conducted in the 2023-2024 cropping season was very low, and maize yield variability was explained by the additive effects of variety type (\u003cem\u003ep\u003c/em\u003e \u0026lt; 0.001) and fertilizer regime (\u003cem\u003ep\u003c/em\u003e \u0026lt; 0.001) in both field types (Table 2). In these experiments, maize yield in fertile fields was highest for the medium-duration variety with fertilizer (1.7 t ha\u003csup\u003e-1\u003c/sup\u003e), followed by the early-duration variety with fertilizer (1.3 t ha\u003csup\u003e-1\u003c/sup\u003e), medium-duration variety without fertilizer (1.1 t ha\u003csup\u003e-1\u003c/sup\u003e), and early-duration variety without fertilizer (0.8 t ha\u003csup\u003e-1\u003c/sup\u003e, Fig. 2c). Similar results were observed in infertile fields, where maize yield was highest for the medium-duration variety with fertilizer (0.9 t ha\u003csup\u003e-1\u003c/sup\u003e), followed by the early-duration variety with fertilizer (0.6 t ha\u003csup\u003e-1\u003c/sup\u003e), medium-duration variety without fertilizer (0.6 t ha\u003csup\u003e-1\u003c/sup\u003e), and early-duration variety without fertilizer (0.4 t ha\u003csup\u003e-1\u003c/sup\u003e, Fig. 2d).\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e3.3 Variation in yield response to variety type, sowing date, and fertilizer regime\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eMaize yield response to sowing date, variety type, and fertilizer regime was highly variable across experiments and field types (Fig. 3). Greater maize yield responses were observed for fertilizer regime than for sowing time and variety type. Maize yield responses to fertilizer regime were not only greater but also more consistent since there were more favorable effects on maize yield with the use of fertilizer than with different sowing dates or variety types. The relative maize yield response to sowing date, variety type, and fertilizer regime is provided in Fig. S2.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe medium-duration variety outyielded the early-duration variety in 34 out of 60 (57%) of the farms x treatment combinations on researcher-managed experiments in fertile fields and less so in infertile fields, i.e., 25 out of 51 (49%) farms x treatment combinations in the 2022-2023 cropping season (Fig. 3a). In these experiments and cropping season, the medium-duration variety outyielded the early-duration variety by 1 t ha\u003csup\u003e-1\u003c/sup\u003e or more on 17 out of 34 (50% ) and five out of 25 (20%) of the farms x treatment combinations in fertile fields and infertile fields, respectively (Fig. 3d), pointing to the benefits of medium-duration varieties in fertile soils. In the 2023-2024 cropping season, two out of six (33%) and (four out 17 (24%) of the farms x treatment combinations showed yield gains with the medium-duration variety equal to or greater than 1.0 t ha\u003csup\u003e-1\u003c/sup\u003e on researcher-managed experiments in fertile and infertile fields, respectively. On farmer-managed experiments, the medium-duration variety outyielded the early-duration variety by 1 t ha\u003csup\u003e-1\u003c/sup\u003e or more on about 14% of the farms x treatment combinations in both fertile (3 out of 23) and infertile fields (20 out 0f 140).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe early sowing date outyielded the intermediate sowing date on 30 out of 40 (75%) of the farms x treatment combinations and the late sowing date on 26 out of 40 (65%) of the farms x treatment combinations on researcher-managed experiments in fertile fields in the 2022-2023 cropping season (Fig. 3b). In these fields, the yield difference between the early sowing date and the intermediate sowing date and between the early sowing date and late sowing date was equal or greater than 1.0 t ha\u003csup\u003e-1\u003c/sup\u003e in 77% and 65% of the farms x treatment combinations, respectively (Fig. 3e). In infertile fields, the early sowing date outyielded the intermediate sowing date on 17 out of 33 (52%) and the late sowing date on 11 out of 34 (32 %) of the farms x treatment combinations (Fig. 3b). In these fields, the yield difference between the early and intermediate sowing dates and between the early and late sowing dates was equal to or greater than 1.0 t ha\u003csup\u003e-1\u003c/sup\u003e on about 24% and 36% of the farm x treatment combinations, respectively. The effect of sowing date could not be assessed for the 2023-2024 cropping season due to dry spells at the time of sowing. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIn the 2022-2023 cropping season, the fertilized treatments outyielded the unfertilized treatments on 43 out of 60 (72%) and on 43 out 51 (84%) of the farms x treatment combinations on researcher-managed experiments in fertile and infertile fields, respectively (Fig. 3c). The yield difference between the fertilized and the unfertilized treatments was equal to or greater than 1.0 t ha\u003csup\u003e-1\u003c/sup\u003e in 60% and 49% of the farms x treatment combinations in fertile and infertile fields, respectively (Fig. 3f). In the 2023-2024 cropping season, the fertilized treatments outyielded the unfertilized treatments on four out of eight (50%) and in 28 out 33 (85%) of the farms x treatment combinations on researcher-managed experiments in fertile and infertile fields, respectively (Fig. 3c). In fertile fields, the largest yield difference between fertilizer regimes was about 0.7 t ha\u003csup\u003e-1\u003c/sup\u003e and was observed in 25% of the farms x treatment combinations. On farmer-managed experiments, the fertilized treatments outyielded the unfertilized treatments on 27 out of 32 (84%) of the farms x treatment combinations in fertile fields. In infertile fields, fertilized treatments outyielded the unfertilized treatments on 160 out of 232 (69%) of the farms x treatment combinations. The yield difference between the fertilized and the unfertilized treatments was equal to or greater than 1.0 t ha\u003csup\u003e-1\u003c/sup\u003e in 22% and 13% of the farms x treatment combinations in fertile and infertile fields, respectively.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e3.4 Effect of plant population at harvest on maize yield\u0026nbsp;\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eVariety type had a statistically significant (\u003cem\u003ep\u003c/em\u003e \u0026lt; 0.05) effect on plant population at harvest, unlike fertilizer and variety x fertilizer whose effects were not statistically significant at the 5% level. The number of maize plants at harvest differed significantly (\u003cem\u003ep\u003c/em\u003e \u0026lt; 0.05) between the early- and medium-duration varieties on both researcher- and farmer-managed experiments, with a higher number of plants observed for the medium-duration variety (Fig. 4a). Plant population at harvest was higher on researcher-managed experiments at about 42,000 plants ha\u003csup\u003e-1\u003c/sup\u003e for the medium-duration variety and 32,000 plants ha\u003csup\u003e-1\u003c/sup\u003e for the early-duration variety. The median plant population on farmer-managed experiments was about 28,000 plants ha\u003csup\u003e-1\u003c/sup\u003e for the medium-duration variety and 22,000 plants ha\u003csup\u003e-1\u003c/sup\u003e for the early-duration variety. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe variation in plant population at harvest was larger in the farmer-managed experiments than in the researcher-managed experiments, and the same was true for the maize yields obtained for a given plant population at harvest (Fig. 4b). Overall, the plant population at harvest varied from 5,000 to 65,000 plants ha\u003csup\u003e-1\u003c/sup\u003e and from 25,000 to 53,333 plants ha\u003csup\u003e-1\u003c/sup\u003e in the farmer- and researcher-managed experiments, respectively. The mean plant population in both experiments was lower than the target value of 53,333 plants ha\u003csup\u003e-1\u003c/sup\u003e in this drought-affected cropping season: about 38,000 plants ha\u003csup\u003e-1\u003c/sup\u003e in the researcher-managed experiments and 26,000 plants ha\u003csup\u003e-1\u003c/sup\u003e in the farmer-managed experiments. The quantile regressions fitted to the 90\u003csup\u003eth\u003c/sup\u003e and 95\u003csup\u003eth\u003c/sup\u003e quantiles indicated that maize yield was maximized at a plant population at harvest of around 50,000 plants ha\u003csup\u003e-1\u003c/sup\u003e, corresponding to 2.0 t ha\u003csup\u003e-1\u003c/sup\u003e at the 90\u003csup\u003eth\u003c/sup\u003e quantile and 2.6 t ha\u003csup\u003e-1\u003c/sup\u003e at the 95\u003csup\u003eth\u003c/sup\u003e quantile (Fig. 4b). A plant population at harvest of more than 50,000 plants ha\u003csup\u003e-1\u003c/sup\u003e was associated with slight decreases in maize yield, probably due to competition between plants. Results thus show a clear contribution of plant population at harvest to maize productivity as well as the importance of other factors at given plant population levels.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e3.5 Profit revenue and return on investment in seeds and fertilizer\u0026nbsp;\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eIn the 2022-2023 cropping season, the results showed that it is profitable to grow improved maize varieties in fertile and infertile fields. The profit for the medium-duration variety was higher than for the early-duration variety in fertile (median of USD 370 ha\u003csup\u003e-1\u003c/sup\u003e vs. USD 200 ha\u003csup\u003e-1\u003c/sup\u003e, respectively) and infertile (median USD 200 vs. USD 100, respectively) fields (Fig. 5a). The maximum profit was about USD 800 for the medium-duration variety and USD 700 for the early-duration variety. The profit for both varieties was comparable across fertilizer treatments, indicating that gains in maize yield due to fertilizer application offset the cost of the fertilizers. The return on investment in improved seed was higher for the early-duration variety than the medium-duration variety and decreased with application of fertilizers; it was slightly lower in infertile fields (Fig. 5d).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIn the 2023-2024 cropping season, the profit and return on investment were on the margin in researcher-managed experiments for both early- and medium-duration varieties (Fig. 5b). The maximum profit was about USD 100 ha\u003csup\u003e-1\u003c/sup\u003e for the varieties. Fertilizer application increased the maximum profit up to USD 250 ha\u003csup\u003e-1\u003c/sup\u003e but increased the number of unprofitable fields by nearly 25%. Overall, fertilizer use was unprofitable on farmer-managed experiments, especially in infertile fields, for both varieties (Fig 5c). The maximum profit in fertile fields ranged from USD 100 ha\u003csup\u003e-1\u003c/sup\u003e to USD 250 ha\u003csup\u003e-1\u003c/sup\u003e.\u003c/p\u003e"},{"header":"4. Discussion","content":"\u003cp\u003eImproving soil fertility and agronomic management are widely recognized as pathways for sustainable intensification of crop production in sub-Saharan Africa (Kuyah et al. \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). This study investigated whether maize yield response to improved varieties and early sowing was conditional on soil nutrient availability, which remains the most limiting factor to maize yields in African smallholder farming (Bekunda et al. \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2010\u003c/span\u003e; Tittonell and Giller \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2013\u003c/span\u003e), including Central Mozambique (Roxburgh and Rodriguez \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e2016\u003c/span\u003e). The experimental approach involved testing two hybrid maize varieties with three sowing dates and two fertilizer regimes over two distinct cropping seasons (one with good rainfall distribution and one characterized by El Ni\u0026ntilde;o-induced drought) and two field types (fertile and infertile). This allowed us to disentangle the relative contribution of genotype, environment, and management and their interactions to maize yields and thus to identify the most pressing constraints to farm yields amid climate change and variation in soil fertility. The farmers\u0026rsquo; soil fertility characterization mostly considered differences in soil texture across fields and subtle differences in nutrient concentrations in the topsoil and subsoil (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe first cropping season of 2022\u0026ndash;2023 was characterized by a normal rainfall amount and distribution (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb), as reflected in the considerably higher maize yields observed in this cropping season compared to the 2023\u0026ndash;2024 cropping season, regardless of agronomic management or soil fertility status. Under such conditions, considerable maize yield gains were observed for early- and medium-duration varieties when sown earlier and with the use of fertilizer (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e2\u003c/span\u003ea), with the medium-duration variety outyielding the early-duration variety in 57% of the farms x treatment combinations. The positive impact of improved maize varieties and of medium- vs. early-duration varieties on maize yield is well-established in Southern Africa (Nyagumbo et al. \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Setimela et al. \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e2017\u003c/span\u003e), as is the importance of timely sowing (Rurinda et al. \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e2015\u003c/span\u003e), particularly under moderate to high soil fertility. Our results in infertile fields further show that maize yield response to sowing date and variety is only observed with the application of fertilizers, pointing to the importance of fertilizer use to improve soil fertility and increase maize production where soil fertility is poor (Amare et al. \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Falconnier et al. \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Silva et al. \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2023a\u003c/span\u003e). We also found that sowing an early-duration variety is riskier than sowing a medium-duration variety in infertile fields; hence, the latter is recommended regardless of soil fertility when early sowing can be ensured. Overall, soil fertility management must be prioritized in Central Mozambique in the short term, certainly when favorable rainfall can be expected, and our results provide recommendations to exploit positive interactions between management practices and their associated risk for farmers under such conditions.\u003c/p\u003e \u003cp\u003eDespite the El Ni\u0026ntilde;o-induced drought in the second cropping season of 2023\u0026ndash;2024, the varieties in fertile fields under researcher management reached yields comparable to those obtained in the first cropping season with fertilizer application in the same field type (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e2\u003c/span\u003ec). The good maize yield in this specific field type in a drought year could be attributed to good soil structure and water-holding capacity, indicating some degree of heterogeneity in soil fertility among the fertile fields (Vanlauwe et al. \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e2007\u003c/span\u003e). This can be explained by differences in past field management practices, differences in resource endowments between farmers (Giller et al. \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2006\u003c/span\u003e), and landscape position (Amede et al. \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Conversely, maize yields in infertile fields were much lower in the second season than in the first cropping season, but fertilized plots yielded about twice that of unfertilized plots under researcher and farmer management. The variability in yield response to fertilizer use in infertile fields can be attributed to (1) differing soil sand content and associated soil water-holding capacity, (2) inappropriate fertilizer rates and types, and (3) the calcium and boron deficiencies observed in some fields. Previous studies in smallholder settings also found infertile fields to be unresponsive to fertilizer use (Giller et al. \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Nziguheba et al. \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2021\u003c/span\u003e) and proposed a focus on integrated soil fertility management as a means to increase and stabilize maize yields in sub-Saharan Africa (Zingore et al. \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2008\u003c/span\u003e). Our findings support such an approach to soil fertility improvement and highlight the importance of adopting improved varieties for food security in dry years under both researcher and farmer management conditions.\u003c/p\u003e \u003cp\u003eBy including researcher-managed and farmer-managed experiments, this study further allowed an evaluation of the impact of improved agronomic management on maize yield. A large difference was found between the productivity obtained under researcher and farmer management in fertile fields (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e2\u003c/span\u003ec) and in infertile fields where fertilizer was applied (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e2\u003c/span\u003ed). This finding points to the critical role of improved agronomy in maize productivity in Southern Africa (see also (Nyagumbo et al. \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2024\u003c/span\u003e; Roxburgh and Rodriguez \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Silva et al. \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2023a\u003c/span\u003e). In this context, improved agronomy goes beyond timely sowing and fertilizer application, since these operations were also handled by researchers in farmer-managed fields, encompassing timely weeding and management practices that can ensure good crop development and plant population at harvest (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e4\u003c/span\u003ea). For instance, ensuring a plant population at harvest of up to the recommended 53,333 plants ha\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e can potentially increase maize yield from 0.6 t ha\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e up to 2.0 t ha\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e under farmer management, roughly twice the average annual maize consumption in the study region. On farmer-managed experiments, most land preparation was done manually or using oxen, with implications on the quality of the seedbed for seed germination and growth, uniformity of seed depth, and access to soil moisture and nutrients. Therefore, multiple factors may contribute to suboptimal plant population at harvest, including in-season droughts, poor soil fertility, variety choice, and untimely field operations due to resource constraints at critical periods of the growing season (Silva et al. \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Tittonell and Giller \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2013\u003c/span\u003e). Indeed, late weeding remains a critical yield-reducing factor for crop production in sub-Saharan Africa (Baudron et al. \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2012b\u003c/span\u003e; Page et al. \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2012\u003c/span\u003e; Silva et al. \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2023a\u003c/span\u003e). In this study, it was not possible to monitor whether weeding on farmer-managed experiments was done at the appropriate time, but the water stress induced by El Ni\u0026ntilde;o in the 2023\u0026ndash;2024 cropping season might have further increased competition for water and nutrients in the case of late weeding. Future research is required to improve of our understanding of the factors driving suboptimal plant populations at harvest across smallholder production environments in Africa.\u003c/p\u003e \u003cp\u003eIn addition to agronomic benefits, improved varieties can increase the profitability of smallholder farms in Central Mozambique, particularly in cropping seasons with good rainfall. Our results indicate that nearly half of the farms achieved a profit of USD 350\u0026ndash;800 ha\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e when the medium-duration variety was used without fertilizer application in the researcher-managed experiments (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e5\u003c/span\u003ea). This is substantial, even when labor costs are not accounted for, given that the minimum wage for the agriculture sector in Mozambique is about USD 100 per month (Governo de Mo\u0026ccedil;ambique \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2024\u003c/span\u003e) and that smallholders in Central Mozambique farm 1.7 ha on average, slightly above the national average of 1.5 ha (MADER \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). Yet, such short-term benefits will lead to soil fertility decline if improved varieties are cultivated without fertilizer in the same field over time (Bekunda et al. \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2010\u003c/span\u003e; Lal and Stewart \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2016\u003c/span\u003e). The low profitability observed in the farmer-managed experiments (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e5\u003c/span\u003ec) is the result of the El Ni\u0026ntilde;o-induced drought. Moreover, investing in improved seeds in infertile soils is often not economically attractive, particularly when fertilizers are used in low rainfall years (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e5\u003c/span\u003e). The rainfall variability observed across two consecutive seasons shows the risk of investing in fertilizers despite its positive effect on increasing yields. The maize yield in the 2023\u0026ndash;2024 cropping season was lower, contributing to lower profitability or even losses when fertilizer was used (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e5\u003c/span\u003ec). If profit and high production are the goals, then fertilizer should be targeted to fertile fields with good water-holding capacity.\u003c/p\u003e \u003cp\u003eEarlier studies have highlighted the importance of mineral fertilizers in the sustainable intensification of African smallholder farming as a means to improved soil fertility and replace nutrients (Amare et al. \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Falconnier et al. \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Silva et al. \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e2023b\u003c/span\u003e; Vanlauwe et al. 2014). Yet, smallholders\u0026rsquo; access to mineral fertilizers remains limited in Mozambique, when compared with neighboring countries in Southern Africa. The response of early- and medium-duration varieties to fertilizers in our experiments (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e2\u003c/span\u003e) shows how fertilizers can significantly increase and sustain yields. While the financial analysis indicates that applying fertilizers in a drought year substantially decreases profit, the economic gains can be large in good years.\u003c/p\u003e \u003cp\u003eSeveral studies have indicated the positive impact of smart agro-input subsidy programs on agricultural productivity, food security, and the nutritional status of poor people in sub-Saharan Africa (Haile et al. 2017; Obayelu et al. \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Mozambique has been implementing agro-input subsidy programs since 2001, yet the outreach is still very low, with only 10% using improved seeds and 8% using inorganic fertilizers. There is a need to combine subsidies with insurance products, such as fertilizer insurance and crop failure insurance, to reduce the negative impact on smallholder farmers\u0026rsquo; livelihoods due to poor yields and low profits as a result of erratic rainfall.\u003c/p\u003e"},{"header":"5. Conclusions","content":"\u003cp\u003eMaize yield variability in Central Mozambique can be explained by the interaction between sowing date, variety type, and fertilizer regime, reinforcing the importance of understanding G \u0026times; E \u0026times; M interactions. Overall, the medium-duration variety had better agronomic performance and economic return compared with the early-duration variety. The low return on investment with application of fertilizer serves as a disincentive for farmers to invest on fertilizers under prevailing grain and fertilizers prices. Measures such as smart agro-input subsidies to reduce fertilizer costs are required to improve access for farmers. Otherwise, farmers will likely continue to cultivate maize without fertilizers, which may compromise longer term sustainability of crop production in relation to soil fertility replenishment over time. Through the application of various complementary methods, these results underscore the potential of improved varieties, sowing time, fertilizer use, and the recommended plant density to sustain maize productivity amid climate change and highlight the associated profitability and risks they carry for smallholders in Southern Africa.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eWilson - is the lead researcher and was responsible for experiment setup, data collection and analysis, and wrote the full manuscript; Jo\u0026atilde;o-contributed with data analysis, prepared the figures and wrote the manuscript; Latha and Upendra - reviewed the manuscript. All authors reviewed the manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eAlimagham S, van Loon MP, Ramirez-Villegas J, Adjei-Nsiah S, Baijukya F, Bala A, Chikowo R, Silva JV, Soul\u0026eacute; AM, Taulya G, Tenorio FA, Tesfaye K, van Ittersum MK (2024) Climate change impact and adaptation of rainfed cereal crops in sub-Saharan Africa. Eur J Agron 155:127137. https://doi.org/10.1016/j.eja.2024.127137\u003c/li\u003e\n \u003cli\u003eAmare T, Alemu E, Bazie Z, Woubet A, Kidanu S, Alemayehu B, Awoke A, Derebe A, Feyisa T, Tamene L, Kerebh\u0026nbsp;B, Wale S, Mulualem A (2022) Yield-limiting plant nutrients for maize production in northwest Ethiopia. Exp Agric 58:e5. https://doi.org/10.1017/S0014479721000302\u003c/li\u003e\n \u003cli\u003eAmede T, Gashaw T, Legesse G, et al (2022) Landscape positions dictating crop fertilizer responses in wheat-based farming systems of East African Highlands. 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Nutr Cycl Agroecosyst 80:267\u0026ndash;282. https://doi.org/10.1007/s10705-007-9142-2\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Food security, genetics, agronomy, smallholder farmers, profitability","lastPublishedDoi":"10.21203/rs.3.rs-5922699/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5922699/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eMaize (\u003cem\u003eZea mays\u003c/em\u003e L.) is the most important cereal staple in sub-Saharan Africa. Yet, smallholders only produce about 20% of what is biophysically possible with agronomic best practices. On-farm researcher- and farmer-managed experiments were conducted in two consecutive cropping seasons in Central Mozambique to disentangle the relative contribution of genotype-by-environment-by-management (G\u0026nbsp;x\u0026nbsp;E\u0026nbsp;x\u0026nbsp;M) interactions to smallholder maize yields in relation to improved varieties, sowing time, and fertilization regime. In the 2022-2023 cropping season, maize yield variability on fertile fields was explained by a three-way interaction between fertilizer regime, sowing date, and variety, whereas on infertile fields, it was explained by fertilizer regime only. The highest yields were obtained with early sowing of a medium- (3.6 t ha\u003csup\u003e-1\u003c/sup\u003e) or early- (3.1 t ha\u003csup\u003e-1\u003c/sup\u003e) duration variety, whereas late sowing yielded the least (1.6 t ha\u003csup\u003e-1\u003c/sup\u003e). In the 2023-2024 cropping season, characterized by El Nino-induced drought, yield variability on fertile fields was explained by variety, with the highest yield associated with the medium-duration variety, and on infertile fields by fertilizer regime. On farmer-managed experiments, maize yield variability was attributed to variety and fertilizer. Profitability with the improved varieties and mineral fertilizers tested depended upon soil fertility and the magnitude of water limitation on maize growth, with trade-offs arising between food security and return on investment in improved genetics and agronomic management. Targeting medium-duration maize varieties in combination with early sowing and nutrient inputs was found to be critical for food security amid climate change.\u003c/p\u003e","manuscriptTitle":"Unraveling the contribution of G x E x M interactions to maize productivity in Central Mozambique amid climate change","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-02-03 04:34:43","doi":"10.21203/rs.3.rs-5922699/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"52d7df46-8e35-4b5d-8089-9559714a915c","owner":[],"postedDate":"February 3rd, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-07-30T10:23:42+00:00","versionOfRecord":[],"versionCreatedAt":"2025-02-03 04:34:43","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-5922699","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5922699","identity":"rs-5922699","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}