{"paper_id":"fe85ac81-be3b-4b11-9120-f711cf0dc1fb","body_text":"Effect of retaining versus removing green prunings on N2 fixation of Cajanus cajan and Sesbania sesban | 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 Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Effect of retaining versus removing green prunings on N 2 fixation of Cajanus cajan and Sesbania sesban Thabo Makhubedu, Brigid Letty, Paramu Mafongoya, Peter Scogings This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-1798187/v1 This work is licensed under a CC BY 4.0 License Status: Under Revision Version 1 posted 6 You are reading this latest preprint version Abstract Aim To compare the effects of retention versus removal of green prunings on symbiotic N 2 fixation of Sesbania sesban and pigeon pea ( Cajanus cajan ). Methods A factorial experiment was conducted to evaluate the effects of retention versus removal of prunings on N 2 fixation of pigeon pea and S. sesban . The plots had three rows of woody legumes, and Zea mays (maize) was planted in between the legume rows. Three prunings were conducted between April 2017 and February 2018 by cutting the legumes back to 75 cm height. Pruned leaves and twigs were either spread evenly (retained) on the soil surface or completely removed (removed). N 2 fixation was measured using the 15 N natural abundance method. Results Whether fresh prunings were retained or removed, pigeon pea derived a significant proportion of its N nutrition from N 2 fixation as compared with S. sesban . Retaining prunings on the soil surface significantly depressed symbiotic N 2 fixation by 18% in pigeon pea and 20.6% in S. sesban compared to when prunings were removed. The results also showed that retaining prunings increased the reliance of pigeon pea and S. sesban on soil N uptake. Conclusions Retaining both leaves and twigs in agroforestry systems reduces N 2 fixation by pigeon pea and S. sesban . The observed reduction in N 2 fixation following retention of prunings could diminish the beneficial effects of N 2 -fixing species on soil N fertility in agroforestry systems. Pigeon pea Sesbania 15N natural abundance N2 fixation Prunings Agroforestry Figures Figure 1 Figure 2 Figure 3 Figure 4 Introduction Smallholder farming systems in southern Africa are continuously losing their capacity to support crop growth and productivity (Barnard and Du Preez 2004 ; Sosibo et al. 2017 ). This issue emanates from nutrient mining associated with continuous cultivation of staple food crops without adequate nutrient input (Mafongoya et al. 2006 ). The decline in soil fertility is a root cause of persistently lower crop yields on small household farms and contributes considerably to food insecurity in rural poor communities (Sanchez 2002 ). Nitrogen (N) deficiency, in particular, is the major factor limiting productivity of staple food crops such as maize, sorghum and millet in southern Africa (Mafongoya et al. 2006 ). The use of locally derived nutrient sources, such as crop residues, can provide reasonable amounts of N, phosphorus (P), potassium (K) and other mineral nutrients required for crop growth and productivity (Chen et al. 2014 ). However, smallholder farmers in southern Africa often let their livestock feed on crop residues in winter after harvest, use them as fuel, or burn the remaining residues just before the cropping season commences (Tongwane et al. 2016 ). In these situations, alternative sources of N are required to help improve soil fertility and crop productivity in smallholder farming systems. The integration of fast-growing woody species, especially N 2 -fixing legumes, represent an alternative strategy needed for addressing soil N fertility challenges confronted by many resource-poor farmers. In most agroforestry systems, N 2 -fixing trees are regularly pruned to minimize competition and shading of companion crops (Youkhana and Idol 2009 ). The tree prunings can be either retained in the soil to enhance nutrient cycling or removed to provide fodder for livestock (Franzel et al. 2014 ; Henriksen et al. 2002 ; Youkhana and Idol 2009 ). Retention of tree prunings has been shown to increase soil organic matter and N availability, crop yields and N uptake, and also improve soil physical, chemical and biological properties (Isaac et al. 2003 , 2004; Youkhana and Idol 2009 ). Fresh prunings and litter of pigeon pea ( Cajanus cajan ) and S. sesban are capable to recycle 115 and 152 kg N ha − 1 , respectively (Chikowo et al. 2004 ), thus indicating that prunings from woody species could be valuable sources of N for resource-poor farmers. Pigeon pea and S. sesban prunings are high-quality organic inputs (high N but low lignin and polyphenol contents) capable of releasing nutrients into the soil rapidly (Mafongoya et al. 1998 ). While legumes have the ability to derive majority of their N requirements from atmospheric N 2 , they are also capable of taking up soil mineral N like non-N 2 -fixing plants (Unkovich 2012 ). Mapfumo et al ( 1999 ) showed that the percentage of N derived from atmospheric N 2 by pigeon pea decreased with increasing soil N availability. In the context of intercropping systems, this means that the addition of N through fresh prunings and litter can gradually increase the soil N availability leading to the reduction or cessation of N 2 fixation if most of the added mineral N is not taken up by companion crops. Therefore, the beneficial effects of N 2 fixing legumes to soil N fertility in intercropping systems may not be fully realized. The objective of this study was to compare the effects of retention versus removal of green prunings on symbiotic N 2 fixation of S. sesban and pigeon pea. It was hypothesized that the retention of fresh prunings on the soil surface will decrease %Ndfa (percentage of N derived from atmospheric N 2 ) of S. sesban and pigeon pea as compared to their removal. Materials And Methods Description of study site The agroforestry experiment was conducted between November 2016 and February 2018 at Fountainhill Research Station (29°27'S, 30°32'E) situated 2 km outside Wartburg and approximately 30 km northeast of Pietermaritzburg in KwaZulu-Natal, South Africa. The site has an average elevation of 853 m above sea level and receives mean annual rainfall of 805 mm. The rainfall pattern is unimodal and 85% of the rains fall between October and April, followed by a dry season from May to September (Fig. 1 ). During the winter months, the area experiences occasional frost. Experimental design and methodology The experiment commenced in November 2016. The study was set up in a 2 x 2 x 2 factorial experiment and the treatments were arranged in a randomized complete block design (RCBD) with 3 replicates. The combinations of treatment factors were: Factor A: Two woody legume species: S. sesban and pigeon pea. Factor B: Two methods of pruning management: retain (as with a green manure) and remove (as with harvesting of fodder). Factor C: Two dates of sampling i.e. November 2017 and February 2018, referred to as November and February, respectively. Seeds of S. sesban (var. nubica ) used in this study were obtained from natural populations near Empangeni (28°39'S, 31°57'E), KwaZulu-Natal Province, South Africa. The seeds were surface scarified by immersing in boiled water for 10–15 minutes and cooled with five rinses of cool tap water. S. sesban trees were established from seedlings raised in poly bags for 60 d in a glasshouse (24 o C). The most homogeneous seedlings of S. sesban , according to leaf surface area, biomass and height, were selected for transplanting in the field to minimize non-treatment variation among the trees. Long duration pigeon pea plants were established by direct seeding using seeds obtained from a 2-year fallow experiment at Owen Sithole College of Agriculture, Empangeni. Two seeds were sown per hole and, at 90 d after establishment, the seedlings were thinned to one per hole. The plots were 10 m x 7 m in size and included three hedgerows with 13 woody legume plants each. The woody legume species were spaced at 3 m between rows and 0.75 m within rows, giving a population density of 3 900 plants ha − 1 . Maize seeds (OPV Border king) were obtained from a local seed supplier (McDonald seeds Pty Ltd.) in Pietermaritzburg, KwaZulu-Natal. Four rows of maize were planted in the interspaces formed by rows of woody legumes, at 0.3 m within and 0.5 m between rows giving a population of 38, 095 plants ha − 1 . The distance between maize rows and hedgerows was 0.75 m. Two maize seeds were planted per hole, but later thinned to one at four weeks after planting. No synthetic fertilizers or inoculants were applied to plants throughout the duration of this experiment to simulate conditions of smallholder farmers. Plots were weeded using hand hoes during the two cropping seasons. During early plant growth stages, the presence of the rhizobia–legume symbiosis was visually evaluated following a few root excavations. The presence of pink root nodules distributed on roots of test legume species was indicative that the soils in the study site contained sufficient populations of native rhizobia for establishing an effective N 2 -fixing symbiosis. Pruning and sampling for 15 N isotopes The first pruning was conducted in April 2017; subsequent prunings were conducted in November 2017 (end of the dry season) and February 2018 (middle of the rainy season). At pruning, the legume species were cut back to 75 cm height using secateurs. Sampling for 15 N isotopic measurements was conducted at each pruning date from four randomly selected plants in the middle rows. Collected samples were oven-drying for 96 h at 60°C and finely ground into powder using a cross beater mill (Retsch KG, West Germany) for the determination of total N (%N) and 𝛿 15 N natural abundance (𝛿 15 N). Zea mays L. (maize) from unfertilized plots and Panicum maximum from adjacent paths were used as reference plants. For comparing the effects of retaining (for soil fertility improvement) versus removing (for livestock fodder), prunings (twigs and leaves) were evenly spread in the ‘retain’ plots as mulch whereas in the ‘remove’ plots these biomass components were completely removed. 15 N/ 14 N isotopic analysis Symbiotic N 2 fixation of pigeon pea and S. sesban was assessed using the 15 N natural abundance technique (Unkovich et al. 2008). The measurements of 𝛿 15 N (‰) and additionally the %N were performed from aliquots of 1.1 to 1.2 mg subsamples of finely ground plant material. Isotopic analysis was conducted on a Flash EA 1112 Series coupled to a Delta V Plus stable light isotope ratio mass spectrometer via a ConFlo IV system (all equipment supplied by Thermo Fischer, Bremen, Germany), housed at the Stable Isotope Laboratory, Mammal Research Institute, University of Pretoria. The 15 N abundance, expressed as δ 15 N, i.e. parts per million (‰) 15 N excess over atmospheric N 2 , was determined using the following equation (Mariotti et al. 1981 ): $${\\delta }^{15}\\text{N}=\\frac{{(}^{15}\\text{N}{/}^{14}\\text{N}{)}_{\\text{s}\\text{a}\\text{m}\\text{p}\\text{l}\\text{e}}- {(}^{15}\\text{N}{/}^{14}\\text{N}{)}_{\\text{s}\\text{t}\\text{a}\\text{n}\\text{d}\\text{a}\\text{r}\\text{d}}}{{(}^{15}\\text{N}{/}^{14}\\text{N}{)}_{\\text{s}\\text{t}\\text{a}\\text{n}\\text{d}\\text{a}\\text{r}\\text{d}}}\\text{x} 1000$$ where 15 N/ 14 N sample and 15 N/ 14 N standard are respectively ratios of the sample and the standard (atmospheric N 2 ). The international standard for atmospheric N = 0.0036765. The %Ndfa was obtained by comparing the 15 N natural abundance of N 2 -fixing species with that of reference plants (Shearer and Kohl 1986 ): where B value is the 15 N natural abundance of the nodulated test legume when grown with N 2 fixation as the sole source of N for its N nutrition. Due to the unavailability of resources for generating B values for pigeon and S. sesban , the B values used in this study were obtained from literature and were − 0.90 for pigeon pea (Peoples 1989) and − 1.76 for S. sesban (Gathumbi et al. 2002 ), respectively. Statistical analysis All data collected were tested for normality using the Shapiro-Wilk test prior to analyses. Analysis of variance (ANOVA) was done using STATISTICA version 13.3 (TIBCO software Inc). Mean differences were declared at P ≤ 0.05. Results Soil properties of the study site Data on the physical and chemical properties of the soil are presented in Table 1 . Soil texture is sandy loam (mean; 18.0% clay, 5.0% silt, and 77% sand) with an average pH of 4.3, organic carbon 0.65%, total N 0.05%, available phosphorus 0.02 mg g − 1 , potassium 0.08 mg g − 1 , calcium 0.42 mg g − 1 and magnesium 0.10 mg g − 1 in the top 40 cm. Soils (0–80 cm depth) of the experimental site are acidic (pH 4.2). The organic carbon ranged from 0.50–0.80%, total organic N varied from < 0.05–0.07% and available phosphorus was in the range of < 0.01–0.02 mg g − 1 . The amount of potassium, calcium and magnesium were in the range of 0.04–0.08 mg g − 1 , 0.37–0.50 mg g − 1 and 0.10–0.15 mg g − 1 , respectively. Table 1 Mean values of soil properties in the 0 – 80 cm profile before the commencement of the experiment Soil depth (cm) pH Organic C (%) Total organic N (%) Extract P (mg g -1 ) Exchangeable cations (mg g -1 ) Soil texture (%) K Ca Mg Clay Silt Sand 0-20 4.24 0.80 0.07 0.02 0.08 0.42 0.10 18 5.3 76.2 20-40 4.31 0.50 <0.05 0.01 0.04 0.37 0.11 18 4.6 77.3 40-60 4.48 0.50 <0.05 <0.01 0.04 0.50 0.15 - - - 60-80 4.49 0.50 <0.05 <0.01 0.04 0.50 0.15 - - - δ 15 N signatures of reference plants In all the pruning dates, maize consistently recorded the highest mean δ 15 N in shoots as compared to P. maximum. The overall mean δ 15 N value of these reference plants was used to estimate %Ndfa of pigeon pea and S. sesban . In April, an overall reference plant δ 15 N value of + 4.56‰ was used to estimate the %Ndfa whereas the average mean δ 15 N values of + 3.16‰ and + 3.27‰ were used for estimating %Ndfa of the test woody species in November and February, respectively (Table 2 ). Table 2 Shoot δ 15 N (‰) values of reference plants sampled at different pruning dates Sampling date Reference species Number of plants ( n ) δ 15 N (‰) Range Mean Overall mean Pre-treatment Apr-17 P. maximum 5 3.58 – 3.93 3.68 Maize 5 5.31 – 6.01 5.44 4.56 Post-treatment Nov-17 P. maximum 9 2.76 – 3.13 2.91 Maize 9 2.50- 4.80 3.42 3.16 Feb-18 P. maximum 9 2.59 – 3.18 2.85 Maize 9 2.82 – 5.18 3.68 3.27 Pre-treatment symbiotic performance A 2-Way ANOVA on the pre-treatment data revealed no significant interaction between woody legume species and pruning management plots for %N, δ 15 N, %Ndfa, N 2 fixed and soil N uptake of test legume species (Table 3 ). Similarly, the main effect of pruning management plots on measured variables was not significant indicating that soil conditions of the study site were uniform prior to the imposition of experimental treatments. However, the main effect of species was significant for all measured variables. Foliar %N varied considerably among the legume species, with highest values recorded in pigeon pea compared with S. sesban (Table 3 ). Pigeon pea exhibited significantly lower δ 15 N values relative to S. sesban . Because of the low δ 15 N values, %Ndfa estimates of pigeon pea were considerably higher as compared with those recorded for S. sesban . The amounts of N 2 fixed were similarly greater in pigeon pea than S. sesban. However, the amounts of soil N uptake were 4.1-fold higher in S. sesban as compared with pigeon pea (Table 3 ). Table 3 A 2-Way ANOVA of symbiotic performance (measured as 𝛿 15 N, %Ndfa, %N and N 2 fixed) and soil N uptake by pigeon pea and S. sesban prior to imposition of experimental treatments (i.e. retained vs. removed). Data are means ± standard error. Significant differences (p < 0.05) are indicated with dissimilar letters Treatment δ 15 N Ndfa N N 2 fixed Soil N uptake (‰) % % kg ha − 1 kg ha − 1 Legume species Pigeon pea -0.47 ± 0.18b 89.4 ± 2.7a 3.23 ± 0.07a 48.0 ± 2.4a 5.9 ± 1.5b S. sesban 0.59 ± 0.11a 62.9 ± 1.7b 2.96 ± 0.08b 38.2 ± 1.6b 22.7 ± 1.3a Pruning management Retain plots 0.08 ± 0.16a 76.4 ± 3.3a 3.14 ± 0.07a 44.2 ± 2.0a 14.5 ± 2.1a Remove plots 0.03 ± 0.20a 75.9 ± 3.8a 3.04 ± 0.09a 42.1 ± 2.3a 14.1 ± 2.4a F-statistics Species 25.45*** 66.9*** 6.44* 13.0*** 68.2*** Pruning management 0.05NS 0.1NS 0.84NS 0.6NS 0.1NS Species*pruning management 0.54NS 0.2NS 0.45NS 1.2NS 1.1NS Effect of retaining vs removing prunings on symbiotic performance There was no significant interaction between species, pruning management and pruning date for %N, δ 15 N, %Ndfa, N 2 fixed and soil N uptake (Table 4 ). However, the was a significant interaction between species and pruning management for %N, %Ndfa and soil N uptake but not for 𝛿 15 N and N 2 -fixed. Except for %N, there was a significant interaction between species and pruning date for 𝛿 15 N, %Ndfa, N 2 -fixed and soil N uptake. There was a significant interaction between pruning management and pruning date for 𝛿 15 N, %Ndfa and soil N uptake but not for %N and N 2 -fixed (Table 4 ). Table 4 Summary of a 3-Way ANOVA F-statistics on symbiotic performance of pigeon pea and S. sesban plants as affected pruning management and pruning date Source of variation df N 𝛿 15 N Ndfa N 2 -fixed Soil N % (‰) % kg ha − 1 Main effects Species 1 33.6*** 636.9*** 1206.5*** 119.0*** 457.2*** Pruning management 1 1.78NS 1757.9*** 1709.0*** 5.1* 67.4*** Pruning date 1 67.1*** 140.3*** 389.4** 130.1*** 42.9*** 2-Way interactions Species*Pruning management 1 7.9** 2.0NS 6.3* 0.0NS 4.6* Species*Pruning date 1 0.1NS 3242.4*** 3166.4*** 113.5*** 117.8*** Pruning man. *Pruning date 1 3.6NS 26.5*** 29.7*** 2.8NS 12.76*** 3-Way interactions Species*Pruning man. *Pruning date 1 0.4NS 2.3NS 0.9NS 0.2NS 1.0NS For pigeon pea, removing fresh prunings significantly increased foliar %N by 9% compared to when prunings were not removed (Fig. 2 A). In contrast, removing prunings decreased %N of S. sesban by almost 3% as compared with when prunings were retained. Retaining fresh prunings on the soil surface significantly reduced %Ndfa of pigeon pea and S. sesban by 18 and 29%, respectively (Fig. 2 B). As compared with removing prunings, retaining prunings significantly increased soil N uptake by pigeon pea and S. sesban (Fig. 2 C). In both pruning dates, pigeon pea exhibited significantly lower 𝛿 15 N values as compared with S. sesban (Fig. 3 A). As compared with S. sesban , %Ndfa estimates of pigeon pea were significantly higher in November and February (Fig. 3 B). Although the amount of N 2 fixed was similar for both legume species in November, pigeon pea recorded 2.8-fold higher amount of N 2 fixed as compared to S. sesban in February (Fig. 3 C). Compared with pigeon pea, S. sesban recorded 2.2-fold and 7.7-fold higher amount of soil N uptake in November and February, respectively (Fig. 3 D). Whether prunings were removed or retained, the 𝛿 15 N values were significantly higher in November 2017 as compared with February 2018 (Fig. 4 A). Surface retention of green prunings increased, on average, 𝛿 15 N values as compared to when prunings were removed. The %Ndfa estimates were higher in February as compared to November (Fig. 4 B). %Ndfa values were, on average, decreased by retention of tree prunings as compared to their removal. Whether prunings were removed or retained the amount of soil N uptake was significantly lower in November as compared with February (Fig. 4 C). Soil N uptake values were, on average, increased by retention of tree prunings as compared to their removal. Discussion Shoot 𝛿 15 N of reference plants This study assessed the effect of retention versus removal of green prunings on symbiotic N 2 fixation of S. sesban and pigeon pea using the 15 N natural abundance technique. With this method, the choice of a suitable reference plant, which is assumed to represent a measure of isotopic signature of plant available soil N for the target N 2 -fixing plant, is of important consideration (Unkovich et al. 2008). The use of more than one non-N 2 -fixing reference species, especially cereal or grass, is also highly recommended for improving the accuracy of N 2 fixation estimates (Unkovich et al. 2008). In this study P. maximum and maize were used as reference species, and the latter species consistently exhibited greater shoot 𝛿 15 N values across the pruning dates (Table 2 ). The variation in shoot δ 15 N of the reference plants used in this study is indicative of inherent differences in isotopic discrimination among the species, or differences in soil N uptake patterns due to varying root phenology and volume of soil explored. Relative to foliar 𝛿 15 N values of woody species, the shoot 𝛿 15 N range of reference plants was sufficiently large to provide reliable estimates of symbiotic N 2 fixation by the 15 N natural abundance method. Pre-treatment symbiotic performance of test legumes The strong variation in δ 15 N values between the reference plants and test legume species strongly indicate that pigeon pea and S. sesban relied mainly on symbiotic N 2 fixation to satisfy their N requirements (Tables 2 and 3 ), which allowed for reliable assessment of pruning management effects on N 2 fixation of the test species. Similar to what has been reported in a previous study (Chikowo et al. 2004 ), pigeon pea exhibited significantly lower δ 15 N values and consequently higher %Ndfa values as compared to S. sesban (Table 3 ). The mean %Ndfa estimates were 89 and 63% for pigeon pea and S. sesban , respectively, and are within the range of previous reports on pigeon pea symbiotic performance in Zimbabwe (58–100%; Mapfumo et al. 1999 ) or in South Africa (27–92%; Dakora et al. 2015 ) and on S. sesban N 2 fixation in Zimbabwe (42–73%; Chikowo et al. 2004 ) assessed using the 15 N natural abundance technique. Although the test species were established without assessing the presence of microsymbionts capable of forming N 2 -fixing nodules, the higher %Ndfa values obtained in this study confirmed that pigeon pea and S. sesban adapted well to the conditions of the study site, and that both species were able to form a highly functional symbiosis in association with native rhizobia population. Pigeon pea recorded considerably higher %N and amount of N 2 fixed as compared with S. sesban (Table 3 ). The aerial biomass of pigeon pea and S. sesban contained 27–66 kg ha − 1 and 22–54 kg ha − 1 of N, respectively, thus indicating that they could be suitable for use as sources of green manure or fodder for livestock. Previous studies in agroforestry systems showed that Gliricidia sepium could accumulate 35 kg ha − 1 (Hairiah et al. 2000 ) and 31.4 to 38.0 kg ha − 1 (Kaba et al. 2019 ) of N in pruning biomass whilst species such as Flemingia conjesta was shown to fix about 26 kg N ha − 1 (Hairiah et al. 2000 ). The amount of N 2 fixed in prunings obtained in these earlier studies are well within the range of the findings of this current study. S. sesban had higher reliance on soil N as compared with pigeon pea suggesting that the vigorous growth nature of S. sesban could have induced greater N demand which was unmet through symbiotic N 2 fixation. Therefore, that N deficit was obtained through increased sub-soil N capture. Chikowo et al. ( 2004 ) also showed that S. sesban took up considerable amount of N from the soil when compared with pigeon pea. Effects of retaining vs removing prunings on symbiotic performance Foliar mean %N differed considerably among the test species (Fig. 2 A), with greater values in S. sesban relative to pigeon pea, thus highlighting inherent variation in rooting phenology and N uptake patterns among the test species (Palm et al. 2001 ). Because S. sesban achieves more rapid stem and leaf growth compared to pigeon pea (Chirwa et al. 2004 ; Lemage et al. 2021 ), the greater %N in the leaves could be due to greater root development (Lemage et al. 2021 ). This probably enabled it to explore greater soil volumes and take up greater soil N to augment N deficit from symbiotically fixed N. The results of this study show that higher accumulation of soil N due to the decomposition of prunings inhibits symbiotic N 2 fixation of pigeon pea and S. sesban . Lower %Ndfa estimates of test species were consistently recorded when fresh prunings were retained on the soil surface compared to when they were removed (Fig. 2 B). Pigeon pea and S. sesban prunings are high-quality organic inputs (high N but low lignin and polyphenol contents) capable of releasing nutrients into the soil rapidly (Mafongoya et al. 1998 ). The inhibition of symbiotic N 2 fixation following retention of prunings is most likely due to increased mineralized N levels in the root zone of these species. As tree litters are mineralized, the amount of available N in the soil increases with time, this process leading to the cessation of N 2 fixation in aging plantations (Dommergues 1995). Kadiata et al. ( 1998 ) showed that the incorporation of tree prunings into soil significantly reduced the %Ndfa of Gliricidia sepium and Leucaena leucocephala by 17 and 22%, respectively, as compared with when prunings were removed. The results indicate that the benefits from symbiotic N 2 fixation in agroforestry systems can be offset by the amount of N released from tree prunings or residues. Soil N uptake by pigeon pea and S. sesban was significantly increased by retention of prunings compared to their removal (Fig. 2 C), and this could be attributable to the decrease in nodule functioning and N 2 fixation rates associated with elevated levels of N in the root zone of plants. Because N 2 fixation is an energy demanding process, greater reliance on soil N uptake could mean that the N satiety of the species was unmet through decreased N 2 fixation rates. The preferential uptake and assimilation of soil mineral N for meeting N satiety over fixing atmospheric N 2 is common in woody legumes (Dommergues 1995). Pigeon pea exhibited significantly lower δ 15 N compared with S. sesban in both November 2017 and February 2018 (Fig. 3 A). Consequently, pigeon derived a greater proportion of its N nutrition from symbiotic N 2 fixation compared with S. sesban (Fig. 3 B). The reliance on N 2 fixation (%Ndfa) ranged from 54–100% and 27–57% for pigeon pea and S. sesban , respectively. The efficiency of N 2 -fixing activity between soil rhizobia and legumes is known to vary among species (Peoples et al. 2009). The superiority of pigeon pea over S. sesban in terms of symbiotic performance could be attributable to its high symbiotic promiscuity (Vanlauwe et al. 2019 ), and most likely, the presence of high population of compatible native soil rhizobia with greater N 2 -fixing efficiency in the study site. Chikowo et al. ( 2004 ) also reported considerably higher %Ndfa estimates in pigeon pea as compared with S. sesban in improved fallow experiment in Zimbabwe. Due to higher %Ndfa values and most likely biomass, especially in February, pigeon pea accumulated significantly greater amounts of N 2 -fixed compared to S. sesban (Fig. 3 c). S. sesban took up significantly higher soil N compared to pigeon. Lower δ 15 N and hence higher %Ndfa values were recorded in February 2018 as compared with November 2017 (Fig. 4 A and B ) could be as a result of moisture stress and lower biomass at the end of the dry season (November). Environmental factors such as drought and extreme temperatures are known to impact growth and symbiotic functioning of nodulated legumes (Hungria and Vargas 2000 ). Nitrogenase activity has been shown to decrease at low soil moisture levels, probably due to limited supply of C assimilates to the N 2 -fixing nodules (Hungria and Vargas 2000 ; Chaves et al. 2009) or reduced N demand by plants. Nygren and Leblanc (2009) also found that G. sepium trees derived a greater proportion of their N nutrition from symbiotic N 2 fixation in the rainy season as compared with the dry season when water availability in the soil was limiting. Conclusion The findings of this study demonstrated that the tested N 2 -fixing legumes adapted well to the conditions of the study site, and both species obtained more than 60% of their N nutrition from N 2 fixation prior to imposition of treatments. Retaining fresh prunings on the soil surface significantly depressed N 2 fixation rates of pigeon pea and S. sesban . Additionally, retaining prunings also increased reliance of both species on soil mineral N. The effect of retaining prunings on N 2 fixation can be lessened only if N supply from prunings of N 2 -fixing woody legumes is synchronized with N demand of associated plants. Reasonable benefits in terms of net N additions to an agroforestry system N balance are likely to be achieved by maximising rates of N 2 fixation by removing freshly pruned material from the system. Therefore, in smallholder mixed crop-lived stock farming system in Africa it would be more practical to prune woody legumes and retaining in the fields as the source of organic matter and mineral nutrients, especially N for accumulation in the soil. To avoid N accumulation, which will reduce N 2 fixation, it would be practical in mixed crop -livestock farming systems, to only retain prunings during the cropping season when the demand for growing plants is high. Any material pruned during the dry season should be fed to livestock and not retained on the soil surface in the field. Declarations Acknowledgements The authors are thankful to Fountainhill Estate Farm for the provision of the study site and Dr Grant Hall at University of Pretoria, South Africa, for 15 N natural abundance analyses. Financial support from the Water Research Commission of South Africa under project number K5/2492//4 titled ‘Water use of agroforestry systems for food, forage and/or biofuel production’ is gratefully acknowledged. Makhubedu I.T is grateful for a competitive doctoral scholarship from the National Research Foundation of South Africa (101500). Funding This work was supported by the Water Research Commission of South Africa under project number K5/2492//4 titled ‘Water use of agroforestry systems for food, forage and/or biofuel production’. Makhubedu I.T received a scholarship from the National Research Foundation of South Africa (101500). Competing Interests Authors declare they have no financial interests. Author Contributions All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Makhubedu IT and Letty BA. The first draft of the manuscript was written by Makhubedu IT and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript. Data availability The datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request. References Barnard RO, Du Preez CC (2004) Soil fertility in South Africa: the last twenty-five years. S Afr J Plant Soil 21: 301-15. Chen B, Liu E, Tian Q, Yan C, Zhang Y (2014) Soil nitrogen dynamics and crop residues. A review. Agron Sustain Dev 34: 429–42. Chikowo R, Mapfumo P, Nyamugafata P, Giller KE (2004) Woody legume fallow productivity, biological N 2 -fixation and residual benefits to two successive maize crops in Zimbabwe. Plant Soil 262: 303–15. Chirwa TS, Mafongoya PI, Mbewe DN and Chisala BH. 2004. Changes in soil properties and their effects on maize productivity following Sesbania sesban and Cajanus cajan improved fallow systems in Eastern Zambia. Biol. Fertil. Soils 40: 20–27. Dakora FD, Belane AK, Mohale KC, Makhubedu TI, Makhura P, Pule‐Meulenberg F, Mapope N, Mogkelhe SN, Gyogluu C, Phatlane GP, Muhaba S (2015) Food grain legumes: their contribution to soil fertility, food security, and human nutrition/health in Africa. In: F.J. de Bruijn (ed) Biological Nitrogen Fixation Vol 2. Wiley, New York, pp. 1063–1070. Franzel S, Carsan S, Lukuyu B, Sinja J, Wambugu C (2014) Fodder trees for improving livestock productivity and smallholder livelihoods in Africa. Curr Opin Env Sust 6: 98–103. Gathumbi SM, Cadisch G, Giller KE (2002) 15 N natural abundance as a tool for assessing N 2 -fixation of herbaceous, shrub and tree legumes in improved fallows. Soil Biol. Biochem 34: 1059–71. Hairiah K, Van Noordwijk M, Cadisch G (2000) Quantification of biological N 2 fixation of hedgerow trees in Northern Lampung. NJAS - Wagening. J. Life Sci 48: 47–59. Henriksen I, Michelsen A, Schlönvoigt A (2002) Tree species selection and soil tillage in alley cropping systems with Phaseolus vulgaris L. in a humid premontane climate: biomass production, nutrient cycling and crop responses. Plant Soil 240: 145–59. Hungria M, Vargas MA (2000) Environmental factors affecting N 2 fixation in grain legumes in the tropics, with an emphasis on Brazil. Field Crops Res 65: 151–64. Isaac L, Wood CW, Shannon DA (2003) Hedgerow species and environmental conditions effects on soil total C and N and C and N mineralization patterns of soils amended with their prunings. Nutr. Cycl. Agroecosystems 65: 73–87. Kaba JS, Zerbe S, Agnolucci M, Scandellari F, Abunyewa AA, Giovannetti M, Tagliavini M (2019) Atmospheric nitrogen fixation by gliricidia trees ( Gliricidia sepium (Jacq.) Kunth ex Walp.) intercropped with cocoa ( Theobroma cacao L.). Plant Soil 435: 323–36. Kadiata BD, Mulongoy K, Isirimah NO (1998) Effect of tree pruning and pruning application to trees on nitrogen fixation by Leucaena and Gliricidia. Agrofor. Syst 39: 117–28. Lemage B, Tsegaye M, Anmaw Y (2021) Evaluation and demonstration of leguminous shrubs hedgerows intercropping with maize crop. International Journal of Agricultural Research, Innovation and Technology 11: 60-68. Mafongoya PL, Bationo A, Kihara J, Waswa BS (2006) Appropriate technologies to replenish soil fertility in southern Africa. Nutr. Cycl. Agroecosystems 76: 137–51. Mafongoya PL, Giller KE, Palm CA (1998) Decomposition and nitrogen release patterns of tree prunings and litter. Agrofor. Syst 38: 77. Mapfumo P, Giller KE, Mpepereki S, Mafongoya PL (1999) Dinitrogen fixation by pigeonpea of different maturity types on granitic sandy soils in Zimbabwe. Symbiosis 27: 305–18. Mariotti A, Germon JC, Hubert P, Kaiser P, Letolle R, Tardieux A, Tardieux P (1981) Experimental determination of nitrogen kinetic isotope fractionation: some principles; illustration for the denitrification and nitrification processes. Plant Soil 62: 413–30. Palm CA, Gachengo CN, Delve RJ, Cadisch G, Giller KE (2001) Organic inputs for soil fertility management in tropical agroecosystems: application of an organic resource database. Agric. Ecosyst. Environ 83: 27–42. Peoples MB, Faizah AW, Rerkasem B, Herridge DH (1989) Methods of evaluating nitrogen fixation by nodulated legumes in the field. Australian Centre for International Agricultural Research, Canberra. Sanchez PA (2002) Soil fertility and hunger in Africa. Science 295: 2019–20. Shearer G, Kohl DH (1986) N2-fixation in field settings: estimations based on natural 15 N abundance. Funct. Plant Biol 13: 699–756. Sosibo NZ, Muchaonyerwa P, Visser L, Barnard A, Dube E, Tsilo TJ (2017) Soil fertility constraints and yield gaps of irrigation wheat in South Africa. S. Afr. J. Sci 113: 1–9. South African Sugar Association (SASA) Weatherweb http://portal.sasa.org.za/weatherweb/. Accessed 17 June 2019. Tongwane M, Mdlambuzi T, Moeletsi M, Tsubo M, Mliswa V, Grootboom L (2016) Greenhouse gas emissions from different crop production and management practices in South Africa. Environ. Dev 19: 23–35. Unkovich M (2012) Nitrogen fixation in Australian dairy systems: review and prospect. Crop Pasture Sci 63: 787-804. Vanlauwe B, Hungria M, Kanampiu F, Giller KE (2019) The role of legumes in the sustainable intensification of African smallholder agriculture: Lessons learnt and challenges for the future. Agric. Ecosyst. Environ 284: 106583. Youkhana A, Idol T (2009) Tree pruning mulch increases soil C and N in a shaded coffee agroecosystem in Hawaii. Soil Biol. Biochem 41: 2527–34. Cite Share Download PDF Status: Under Revision Version 1 posted Editorial decision: Major revisions 25 Aug, 2022 Reviewers agreed at journal 05 Jul, 2022 Reviewers invited by journal 04 Jul, 2022 Editor invited by journal 03 Jul, 2022 Editor assigned by journal 03 Jul, 2022 First submitted to journal 02 Jul, 2022 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 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-1798187\",\"acceptedTermsAndConditions\":true,\"allowDirectSubmit\":false,\"archivedVersions\":[],\"articleType\":\"Research Article\",\"associatedPublications\":[],\"authors\":[{\"id\":118369380,\"identity\":\"6ffc335e-87ee-4d92-93ad-ba9675e43c1b\",\"order_by\":0,\"name\":\"Thabo Makhubedu\",\"email\":\"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA4UlEQVRIiWNgGAWjYBACNiBmbGxgSGBgSGB8AOTw8BHUwobQwmwA0sJGjDUwLWwSMHvxAj757sSPM3cczuNnzzGr/JpjJ8PGwPzw0Q28DuPdLLnxzOFiyZ43ZrdltyUDHcZmbJyDX8sGyYdthxM33Mgxuy25jRmohYdNmoCWzT9BWvYDtRRLbqsnSss2yY0gWyRyzBg/bjtMjJbcbZYz29KLJc48K5Zm3Hach42ZgF/km89uvtnbZp3H35688ePPbdX2/OzNDx/j04ICmHnAJLHKQYDxBymqR8EoGAWjYMQAAC/oR5NnWMPoAAAAAElFTkSuQmCC\",\"orcid\":\"https://orcid.org/0000-0001-5540-174X\",\"institution\":\"University of KwaZulu-Natal School of Agricultural Earth and Environmental Sciences\",\"correspondingAuthor\":true,\"submittingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Thabo\",\"middleName\":\"\",\"lastName\":\"Makhubedu\",\"suffix\":\"\"},{\"id\":118369381,\"identity\":\"dd3b3203-80ed-4d2b-b298-ff3c747f9932\",\"order_by\":1,\"name\":\"Brigid Letty\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"\",\"correspondingAuthor\":false,\"submittingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Brigid\",\"middleName\":\"\",\"lastName\":\"Letty\",\"suffix\":\"\"},{\"id\":118369382,\"identity\":\"1c4463ae-b270-45bb-a736-f88f5962d23b\",\"order_by\":2,\"name\":\"Paramu Mafongoya\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"\",\"correspondingAuthor\":false,\"submittingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Paramu\",\"middleName\":\"\",\"lastName\":\"Mafongoya\",\"suffix\":\"\"},{\"id\":118369383,\"identity\":\"a4eea4b8-1f5d-456d-a719-63122a440f82\",\"order_by\":3,\"name\":\"Peter Scogings\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"\",\"correspondingAuthor\":false,\"submittingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Peter\",\"middleName\":\"\",\"lastName\":\"Scogings\",\"suffix\":\"\"}],\"badges\":[],\"createdAt\":\"2022-06-27 05:11:48\",\"currentVersionCode\":1,\"declarations\":\"\",\"doi\":\"10.21203/rs.3.rs-1798187/v1\",\"doiUrl\":\"https://doi.org/10.21203/rs.3.rs-1798187/v1\",\"draftVersion\":[],\"editorialEvents\":[],\"editorialNote\":\"\",\"failedWorkflow\":false,\"files\":[{\"id\":24054881,\"identity\":\"054a6406-b7e5-4328-9099-d500c9dcc671\",\"added_by\":\"auto\",\"created_at\":\"2022-07-19 18:44:36\",\"extension\":\"png\",\"order_by\":1,\"title\":\"Figure 1\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":26281,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eRainfall distribution and average temperature between November 2016 and February 2018 according to the SASA weather website (SASA, 2019)\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"1.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-1798187/v1/9d6d45458024aa8893c9eebf.png\"},{\"id\":24054878,\"identity\":\"9947c7cf-cd6d-4a6d-b123-080272c4f54d\",\"added_by\":\"auto\",\"created_at\":\"2022-07-19 18:44:36\",\"extension\":\"png\",\"order_by\":2,\"title\":\"Figure 2\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":26749,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003e Interaction between woody legume species and pruning management on \\u003cstrong\\u003ea\\u003c/strong\\u003e) %N, \\u003cstrong\\u003eb\\u003c/strong\\u003e) %Ndfa and \\u003cstrong\\u003ec\\u003c/strong\\u003e) soil N uptake. Data are means ± standard error. Significant differences (p\\u0026lt;0.05) are indicated with dissimilar letters\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"2.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-1798187/v1/c407433d4f675b3c27c89a78.png\"},{\"id\":24055286,\"identity\":\"20d39b15-2b43-4c87-a2ca-4cab46b63537\",\"added_by\":\"auto\",\"created_at\":\"2022-07-19 18:49:36\",\"extension\":\"png\",\"order_by\":3,\"title\":\"Figure 3\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":32411,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eThe interaction between woody legume species and pruning date (Nov 2017 versus Feb 2018) on \\u003cstrong\\u003ea\\u003c/strong\\u003e) 𝛿\\u003csup\\u003e15\\u003c/sup\\u003eN, \\u003cstrong\\u003eb\\u003c/strong\\u003e) %Ndfa, \\u003cstrong\\u003ec\\u003c/strong\\u003e) N\\u003csub\\u003e2\\u003c/sub\\u003e-fixed and \\u003cstrong\\u003ed\\u003c/strong\\u003e) soil N uptake.\\u003cem\\u003e \\u003c/em\\u003eData are means ± standard error. Significant differences (p\\u0026lt;0.05) are indicated with dissimilar letters\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"3.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-1798187/v1/e9e56490ce9c08e206166f63.png\"},{\"id\":24054879,\"identity\":\"ffbb726c-c55f-49b8-82e1-b8a4ff9c095a\",\"added_by\":\"auto\",\"created_at\":\"2022-07-19 18:44:36\",\"extension\":\"png\",\"order_by\":4,\"title\":\"Figure 4\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":27589,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eThe interaction between pruning management and pruning date (Nov 2017 versus Feb 2018) on \\u003cstrong\\u003ea\\u003c/strong\\u003e) 𝛿\\u003csup\\u003e15\\u003c/sup\\u003eN, \\u003cstrong\\u003eb\\u003c/strong\\u003e) %Ndfa, and \\u003cstrong\\u003ec\\u003c/strong\\u003e) soil N uptake when combining pigeon pea and \\u003cem\\u003eS. sesban\\u003c/em\\u003e data. Data are means ± standard error. Significant differences (p\\u0026lt;0.05) are indicated with dissimilar letters\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"4.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-1798187/v1/0d93ad563141a9e5708d0616.png\"},{\"id\":24055287,\"identity\":\"96920989-ba53-4a12-a731-94acd10b50e6\",\"added_by\":\"auto\",\"created_at\":\"2022-07-19 18:49:40\",\"extension\":\"pdf\",\"order_by\":0,\"title\":\"\",\"display\":\"\",\"copyAsset\":false,\"role\":\"manuscript-pdf\",\"size\":356539,\"visible\":true,\"origin\":\"\",\"legend\":\"\",\"description\":\"\",\"filename\":\"manuscript.pdf\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-1798187/v1/c1134481-926a-49d5-bbfc-549740a9fd40.pdf\"}],\"financialInterests\":\"\",\"formattedTitle\":\"\\u003cp\\u003eEffect of retaining versus removing green prunings on N\\u003csub\\u003e2\\u003c/sub\\u003e fixation of \\u003cem\\u003eCajanus cajan \\u003c/em\\u003eand \\u003cem\\u003eSesbania sesban\\u003c/em\\u003e\\u003c/p\\u003e\",\"fulltext\":[{\"header\":\"Introduction\",\"content\":\"\\u003cp\\u003eSmallholder farming systems in southern Africa are continuously losing their capacity to support crop growth and productivity (Barnard and Du Preez \\u003cspan citationid=\\\"CR1\\\" class=\\\"CitationRef\\\"\\u003e2004\\u003c/span\\u003e; Sosibo et al. \\u003cspan citationid=\\\"CR24\\\" class=\\\"CitationRef\\\"\\u003e2017\\u003c/span\\u003e). This issue emanates from nutrient mining associated with continuous cultivation of staple food crops without adequate nutrient input (Mafongoya et al. \\u003cspan citationid=\\\"CR16\\\" class=\\\"CitationRef\\\"\\u003e2006\\u003c/span\\u003e). The decline in soil fertility is a root cause of persistently lower crop yields on small household farms and contributes considerably to food insecurity in rural poor communities (Sanchez \\u003cspan citationid=\\\"CR22\\\" class=\\\"CitationRef\\\"\\u003e2002\\u003c/span\\u003e). Nitrogen (N) deficiency, in particular, is the major factor limiting productivity of staple food crops such as maize, sorghum and millet in southern Africa (Mafongoya et al. \\u003cspan citationid=\\\"CR16\\\" class=\\\"CitationRef\\\"\\u003e2006\\u003c/span\\u003e).\\u003c/p\\u003e \\u003cp\\u003eThe use of locally derived nutrient sources, such as crop residues, can provide reasonable amounts of N, phosphorus (P), potassium (K) and other mineral nutrients required for crop growth and productivity (Chen et al. \\u003cspan citationid=\\\"CR2\\\" class=\\\"CitationRef\\\"\\u003e2014\\u003c/span\\u003e). However, smallholder farmers in southern Africa often let their livestock feed on crop residues in winter after harvest, use them as fuel, or burn the remaining residues just before the cropping season commences (Tongwane et al. \\u003cspan citationid=\\\"CR26\\\" class=\\\"CitationRef\\\"\\u003e2016\\u003c/span\\u003e). In these situations, alternative sources of N are required to help improve soil fertility and crop productivity in smallholder farming systems.\\u003c/p\\u003e \\u003cp\\u003eThe integration of fast-growing woody species, especially N\\u003csub\\u003e2\\u003c/sub\\u003e-fixing legumes, represent an alternative strategy needed for addressing soil N fertility challenges confronted by many resource-poor farmers. In most agroforestry systems, N\\u003csub\\u003e2\\u003c/sub\\u003e-fixing trees are regularly pruned to minimize competition and shading of companion crops (Youkhana and Idol \\u003cspan citationid=\\\"CR29\\\" class=\\\"CitationRef\\\"\\u003e2009\\u003c/span\\u003e). The tree prunings can be either retained in the soil to enhance nutrient cycling or removed to provide fodder for livestock (Franzel et al. \\u003cspan citationid=\\\"CR7\\\" class=\\\"CitationRef\\\"\\u003e2014\\u003c/span\\u003e; Henriksen et al. \\u003cspan citationid=\\\"CR10\\\" class=\\\"CitationRef\\\"\\u003e2002\\u003c/span\\u003e; Youkhana and Idol \\u003cspan citationid=\\\"CR29\\\" class=\\\"CitationRef\\\"\\u003e2009\\u003c/span\\u003e). Retention of tree prunings has been shown to increase soil organic matter and N availability, crop yields and N uptake, and also improve soil physical, chemical and biological properties (Isaac et al. \\u003cspan citationid=\\\"CR12\\\" class=\\\"CitationRef\\\"\\u003e2003\\u003c/span\\u003e, 2004; Youkhana and Idol \\u003cspan citationid=\\\"CR29\\\" class=\\\"CitationRef\\\"\\u003e2009\\u003c/span\\u003e).\\u003c/p\\u003e \\u003cp\\u003eFresh prunings and litter of pigeon pea (\\u003cem\\u003eCajanus cajan\\u003c/em\\u003e) and \\u003cem\\u003eS. sesban\\u003c/em\\u003e are capable to recycle 115 and 152 kg N ha\\u003csup\\u003e\\u0026minus;\\u0026thinsp;1\\u003c/sup\\u003e, respectively (Chikowo et al. \\u003cspan citationid=\\\"CR3\\\" class=\\\"CitationRef\\\"\\u003e2004\\u003c/span\\u003e), thus indicating that prunings from woody species could be valuable sources of N for resource-poor farmers. Pigeon pea and \\u003cem\\u003eS. sesban\\u003c/em\\u003e prunings are high-quality organic inputs (high N but low lignin and polyphenol contents) capable of releasing nutrients into the soil rapidly (Mafongoya et al. \\u003cspan citationid=\\\"CR17\\\" class=\\\"CitationRef\\\"\\u003e1998\\u003c/span\\u003e). While legumes have the ability to derive majority of their N requirements from atmospheric N\\u003csub\\u003e2\\u003c/sub\\u003e, they are also capable of taking up soil mineral N like non-N\\u003csub\\u003e2\\u003c/sub\\u003e-fixing plants (Unkovich \\u003cspan citationid=\\\"CR27\\\" class=\\\"CitationRef\\\"\\u003e2012\\u003c/span\\u003e). Mapfumo et al (\\u003cspan citationid=\\\"CR18\\\" class=\\\"CitationRef\\\"\\u003e1999\\u003c/span\\u003e) showed that the percentage of N derived from atmospheric N\\u003csub\\u003e2\\u003c/sub\\u003e by pigeon pea decreased with increasing soil N availability. In the context of intercropping systems, this means that the addition of N through fresh prunings and litter can gradually increase the soil N availability leading to the reduction or cessation of N\\u003csub\\u003e2\\u003c/sub\\u003e fixation if most of the added mineral N is not taken up by companion crops. Therefore, the beneficial effects of N\\u003csub\\u003e2\\u003c/sub\\u003e fixing legumes to soil N fertility in intercropping systems may not be fully realized.\\u003c/p\\u003e \\u003cp\\u003eThe objective of this study was to compare the effects of retention versus removal of green prunings on symbiotic N\\u003csub\\u003e2\\u003c/sub\\u003e fixation of \\u003cem\\u003eS. sesban\\u003c/em\\u003e and pigeon pea. It was hypothesized that the retention of fresh prunings on the soil surface will decrease %Ndfa (percentage of N derived from atmospheric N\\u003csub\\u003e2\\u003c/sub\\u003e) of \\u003cem\\u003eS. sesban\\u003c/em\\u003e and pigeon pea as compared to their removal.\\u003c/p\\u003e\"},{\"header\":\"Materials And Methods\",\"content\":\"\\u003cp\\u003eDescription of study site\\u003c/p\\u003e \\u003cp\\u003eThe agroforestry experiment was conducted between November 2016 and February 2018 at Fountainhill Research Station (29\\u0026deg;27'S, 30\\u0026deg;32'E) situated 2 km outside Wartburg and approximately 30 km northeast of Pietermaritzburg in KwaZulu-Natal, South Africa. The site has an average elevation of 853 m above sea level and receives mean annual rainfall of 805 mm. The rainfall pattern is unimodal and 85% of the rains fall between October and April, followed by a dry season from May to September (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig1\\\" class=\\\"InternalRef\\\"\\u003e1\\u003c/span\\u003e). During the winter months, the area experiences occasional frost.\\u003c/p\\u003e \\u003cp\\u003e\\u003cstrong\\u003eExperimental design and methodology\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eThe experiment commenced in November 2016. The study was set up in a 2 x 2 x 2 factorial experiment and the treatments were arranged in a randomized complete block design (RCBD) with 3 replicates. The combinations of treatment factors were:\\u003c/p\\u003e\\n\\u003cp\\u003eFactor A: Two woody legume species: \\u003cem\\u003eS. sesban\\u003c/em\\u003e and pigeon pea.\\u003c/p\\u003e\\n\\u003cp\\u003eFactor B: Two methods of pruning management: retain (as with a green manure) and remove (as with harvesting of fodder).\\u003c/p\\u003e\\n\\u003cp\\u003eFactor C: Two dates of sampling i.e. November 2017 and February 2018, referred to as November and February, respectively.\\u003c/p\\u003e\\n\\u003cp\\u003eSeeds of \\u003cem\\u003eS. sesban\\u003c/em\\u003e (var. \\u003cem\\u003enubica\\u003c/em\\u003e) used in this study were obtained from natural populations near Empangeni (28\\u0026deg;39\\u0026apos;S, 31\\u0026deg;57\\u0026apos;E), KwaZulu-Natal Province, South Africa. The seeds were surface scarified by immersing in boiled water for 10\\u0026ndash;15 minutes and cooled with five rinses of cool tap water. \\u003cem\\u003eS. sesban\\u003c/em\\u003e trees were established from seedlings raised in poly bags for 60 d in a glasshouse (24\\u003csup\\u003eo\\u003c/sup\\u003eC). The most homogeneous seedlings of \\u003cem\\u003eS. sesban\\u003c/em\\u003e, according to leaf surface area, biomass and height, were selected for transplanting in the field to minimize non-treatment variation among the trees. Long duration pigeon pea plants were established by direct seeding using seeds obtained from a 2-year fallow experiment at Owen Sithole College of Agriculture, Empangeni. Two seeds were sown per hole and, at 90 d after establishment, the seedlings were thinned to one per hole.\\u003c/p\\u003e\\n\\u003cp\\u003eThe plots were 10 m x 7 m in size and included three hedgerows with 13 woody legume plants each. The woody legume species were spaced at 3 m between rows and 0.75 m within rows, giving a population density of 3 900 plants ha\\u003csup\\u003e\\u0026minus;\\u0026thinsp;1\\u003c/sup\\u003e. Maize seeds (OPV Border king) were obtained from a local seed supplier (McDonald seeds Pty Ltd.) in Pietermaritzburg, KwaZulu-Natal. Four rows of maize were planted in the interspaces formed by rows of woody legumes, at 0.3 m within and 0.5 m between rows giving a population of 38, 095 plants ha\\u003csup\\u003e\\u0026minus;\\u0026thinsp;1\\u003c/sup\\u003e. The distance between maize rows and hedgerows was 0.75 m. Two maize seeds were planted per hole, but later thinned to one at four weeks after planting.\\u003c/p\\u003e\\n\\u003cp\\u003eNo synthetic fertilizers or inoculants were applied to plants throughout the duration of this experiment to simulate conditions of smallholder farmers. Plots were weeded using hand hoes during the two cropping seasons. During early plant growth stages, the presence of the rhizobia\\u0026ndash;legume symbiosis was visually evaluated following a few root excavations. The presence of pink root nodules distributed on roots of test legume species was indicative that the soils in the study site contained sufficient populations of native rhizobia for establishing an effective N\\u003csub\\u003e2\\u003c/sub\\u003e-fixing symbiosis.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003ePruning and sampling for \\u003csup\\u003e15\\u003c/sup\\u003eN isotopes\\u0026nbsp;\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eThe first pruning was conducted in April 2017; subsequent prunings were conducted in November 2017 (end of the dry season) and February 2018 (middle of the rainy season). At pruning, the legume species were cut back to 75 cm height using secateurs. Sampling for \\u003csup\\u003e15\\u003c/sup\\u003eN isotopic measurements was conducted at each pruning date from four randomly selected plants in the middle rows. Collected samples were oven-drying for 96 h at 60\\u0026deg;C and finely ground into powder using a cross beater mill (Retsch KG, West Germany) for the determination of total N (%N) and 𝛿\\u003csup\\u003e15\\u003c/sup\\u003eN natural abundance (𝛿\\u003csup\\u003e15\\u003c/sup\\u003eN). \\u003cem\\u003eZea mays\\u003c/em\\u003e L. (maize) from unfertilized plots and \\u003cem\\u003ePanicum maximum\\u003c/em\\u003e from adjacent paths were used as reference plants. For comparing the effects of retaining (for soil fertility improvement) versus removing (for livestock fodder), prunings (twigs and leaves) were evenly spread in the \\u0026lsquo;retain\\u0026rsquo; plots as mulch whereas in the \\u0026lsquo;remove\\u0026rsquo; plots these biomass components were completely removed.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003csup\\u003e15\\u003c/sup\\u003eN/\\u003csup\\u003e14\\u003c/sup\\u003eN isotopic analysis\\u003c/p\\u003e\\n\\u003cp\\u003eSymbiotic N\\u003csub\\u003e2\\u003c/sub\\u003e fixation of pigeon pea and \\u003cem\\u003eS. sesban\\u003c/em\\u003e was assessed using the \\u003csup\\u003e15\\u003c/sup\\u003eN natural abundance technique (Unkovich et al. 2008). The measurements of 𝛿\\u003csup\\u003e15\\u003c/sup\\u003eN (\\u0026permil;) and additionally the %N were performed from aliquots of 1.1 to 1.2 mg subsamples of finely ground plant material. Isotopic analysis was conducted on a Flash EA 1112 Series coupled to a Delta V Plus stable light isotope ratio mass spectrometer via a ConFlo IV system (all equipment supplied by Thermo Fischer, Bremen, Germany), housed at the Stable Isotope Laboratory, Mammal Research Institute, University of Pretoria.\\u003c/p\\u003e\\n\\u003cp\\u003eThe \\u003csup\\u003e15\\u003c/sup\\u003eN abundance, expressed as \\u0026delta;\\u003csup\\u003e15\\u003c/sup\\u003eN, i.e. parts per million (\\u0026permil;) \\u003csup\\u003e15\\u003c/sup\\u003eN excess over atmospheric N\\u003csub\\u003e2\\u003c/sub\\u003e, was determined using the following equation (Mariotti et al. \\u003cspan class=\\\"CitationRef\\\"\\u003e1981\\u003c/span\\u003e):\\u003c/p\\u003e\\n\\u003cdiv class=\\\"Equation\\\" id=\\\"Equa\\\"\\u003e\\n \\u003cdiv class=\\\"mathdisplay\\\" id=\\\"FileID_Equa\\\" name=\\\"EquationSource\\\"\\u003e$${\\\\delta }^{15}\\\\text{N}=\\\\frac{{(}^{15}\\\\text{N}{/}^{14}\\\\text{N}{)}_{\\\\text{s}\\\\text{a}\\\\text{m}\\\\text{p}\\\\text{l}\\\\text{e}}- {(}^{15}\\\\text{N}{/}^{14}\\\\text{N}{)}_{\\\\text{s}\\\\text{t}\\\\text{a}\\\\text{n}\\\\text{d}\\\\text{a}\\\\text{r}\\\\text{d}}}{{(}^{15}\\\\text{N}{/}^{14}\\\\text{N}{)}_{\\\\text{s}\\\\text{t}\\\\text{a}\\\\text{n}\\\\text{d}\\\\text{a}\\\\text{r}\\\\text{d}}}\\\\text{x} 1000$$\\u003c/div\\u003e\\n\\u003c/div\\u003e\\n\\u003cp\\u003ewhere\\u003csup\\u003e15\\u003c/sup\\u003eN/\\u003csup\\u003e14\\u003c/sup\\u003eN sample and \\u003csup\\u003e15\\u003c/sup\\u003eN/\\u003csup\\u003e14\\u003c/sup\\u003eN standard are respectively ratios of the sample and the standard (atmospheric N\\u003csub\\u003e2\\u003c/sub\\u003e). The international standard for atmospheric N\\u0026thinsp;=\\u0026thinsp;0.0036765.\\u003c/p\\u003e\\n\\u003cp\\u003eThe %Ndfa was obtained by comparing the \\u003csup\\u003e15\\u003c/sup\\u003eN natural abundance of N\\u003csub\\u003e2\\u003c/sub\\u003e-fixing species with that of reference plants (Shearer and Kohl \\u003cspan class=\\\"CitationRef\\\"\\u003e1986\\u003c/span\\u003e):\\u003c/p\\u003e\\n\\u003cdiv class=\\\"Equation\\\" id=\\\"Equb\\\"\\u003e\\n \\u003cdiv class=\\\"mathdisplay\\\" id=\\\"FileID_Equb\\\" name=\\\"EquationSource\\\"\\u003e\\u003cimg src=\\\"data:image/png;base64,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\\\"\\u003e\\u003c/div\\u003e\\n\\u003c/div\\u003e\\n\\u003cp\\u003ewhere B value is the \\u003csup\\u003e15\\u003c/sup\\u003eN natural abundance of the nodulated test legume when grown with N\\u003csub\\u003e2\\u003c/sub\\u003e fixation as the sole source of N for its N nutrition. Due to the unavailability of resources for generating B values for pigeon and \\u003cem\\u003eS. sesban\\u003c/em\\u003e, the B values used in this study were obtained from literature and were \\u0026minus;\\u0026thinsp;0.90 for pigeon pea (Peoples 1989) and \\u0026minus;\\u0026thinsp;1.76 for \\u003cem\\u003eS. sesban\\u003c/em\\u003e (Gathumbi et al. \\u003cspan class=\\\"CitationRef\\\"\\u003e2002\\u003c/span\\u003e), respectively.\\u003c/p\\u003e\\n\\u003cdiv class=\\\"Section2\\\" id=\\\"Sec5\\\"\\u003e\\n \\u003cp\\u003e\\u003cstrong\\u003eStatistical analysis\\u003c/strong\\u003e\\u003c/p\\u003e\\n \\u003cp\\u003eAll data collected were tested for normality using the Shapiro-Wilk test prior to analyses. Analysis of variance (ANOVA) was done using STATISTICA version 13.3 (TIBCO software Inc). Mean differences were declared at P\\u0026thinsp;\\u0026le;\\u0026thinsp;0.05.\\u003c/p\\u003e\\n\\u003c/div\\u003e\"},{\"header\":\"Results\",\"content\":\"\\u003cp\\u003eSoil properties of the study site\\u003c/p\\u003e\\n\\u003cp\\u003eData on the physical and chemical properties of the soil are presented in Table \\u003cspan class=\\\"InternalRef\\\"\\u003e1\\u003c/span\\u003e. Soil texture is sandy loam (mean; 18.0% clay, 5.0% silt, and 77% sand) with an average pH of 4.3, organic carbon 0.65%, total N 0.05%, available phosphorus 0.02 mg g\\u003csup\\u003e\\u0026minus;\\u0026thinsp;1\\u003c/sup\\u003e, potassium 0.08 mg g\\u003csup\\u003e\\u0026minus;\\u0026thinsp;1\\u003c/sup\\u003e, calcium 0.42 mg g\\u003csup\\u003e\\u0026minus;\\u0026thinsp;1\\u003c/sup\\u003e and magnesium 0.10 mg g\\u003csup\\u003e\\u0026minus;\\u0026thinsp;1\\u003c/sup\\u003e in the top 40 cm. Soils (0\\u0026ndash;80 cm depth) of the experimental site are acidic (pH 4.2). The organic carbon ranged from 0.50\\u0026ndash;0.80%, total organic N varied from \\u0026lt;\\u0026thinsp;0.05\\u0026ndash;0.07% and available phosphorus was in the range of \\u0026lt;\\u0026thinsp;0.01\\u0026ndash;0.02 mg g\\u003csup\\u003e\\u0026minus;\\u0026thinsp;1\\u003c/sup\\u003e. The amount of potassium, calcium and magnesium were in the range of 0.04\\u0026ndash;0.08 mg g\\u003csup\\u003e\\u0026minus;\\u0026thinsp;1\\u003c/sup\\u003e, 0.37\\u0026ndash;0.50 mg g\\u003csup\\u003e\\u0026minus;\\u0026thinsp;1\\u003c/sup\\u003e and 0.10\\u0026ndash;0.15 mg g\\u003csup\\u003e\\u0026minus;\\u0026thinsp;1\\u003c/sup\\u003e, respectively.\\u0026nbsp;\\u003c/p\\u003e\\n\\u003cp\\u003eTable 1\\u0026nbsp;Mean values of soil properties\\u0026nbsp;in the 0 \\u0026ndash; 80 cm profile before the commencement of the experiment\\u003c/p\\u003e\\n\\u003ctable border=\\\"1\\\" cellpadding=\\\"0\\\" cellspacing=\\\"0\\\" width=\\\"0\\\"\\u003e\\n \\u003ctbody\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd rowspan=\\\"2\\\" style=\\\"width: 9.7717%;\\\" width=\\\"12.602291325695582%\\\"\\u003e\\n \\u003cp\\u003eSoil depth (cm)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd rowspan=\\\"2\\\" style=\\\"width: 4.9816%;\\\" width=\\\"6.219312602291326%\\\"\\u003e\\n \\u003cp\\u003epH\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd rowspan=\\\"2\\\" style=\\\"width: 9.3885%;\\\" width=\\\"11.783960720130933%\\\"\\u003e\\n \\u003cp\\u003eOrganic C\\u003c/p\\u003e\\n \\u003cp\\u003e(%)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd rowspan=\\\"2\\\" style=\\\"width: 9.7717%;\\\" width=\\\"12.274959083469723%\\\"\\u003e\\n \\u003cp\\u003eTotal organic N\\u003c/p\\u003e\\n \\u003cp\\u003e(%)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd rowspan=\\\"2\\\" style=\\\"width: 8.5263%;\\\" width=\\\"10.638297872340425%\\\"\\u003e\\n \\u003cp\\u003eExtract P\\u003c/p\\u003e\\n \\u003cp\\u003e(mg g\\u003csup\\u003e-1\\u003c/sup\\u003e)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd colspan=\\\"3\\\" style=\\\"width: 34.2009%;\\\" valign=\\\"bottom\\\" width=\\\"21.44026186579378%\\\"\\u003e\\n \\u003cp\\u003eExchangeable cations (mg g\\u003csup\\u003e-1\\u003c/sup\\u003e)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd colspan=\\\"3\\\" style=\\\"width: 8.4305%;\\\" valign=\\\"bottom\\\" width=\\\"21.93126022913257%\\\"\\u003e\\n \\u003cp\\u003eSoil texture\\u003c/p\\u003e\\n \\u003cp\\u003e(%)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd style=\\\"width: 12.7415%;\\\" valign=\\\"bottom\\\" width=\\\"16.607773851590107%\\\"\\u003e\\n \\u003cp\\u003eK\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 12.7415%;\\\" valign=\\\"bottom\\\" width=\\\"16.607773851590107%\\\"\\u003e\\n \\u003cp\\u003eCa\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 9.6759%;\\\" valign=\\\"bottom\\\" width=\\\"19.434628975265017%\\\"\\u003e\\n \\u003cp\\u003eMg\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 2.9698%;\\\" valign=\\\"bottom\\\" width=\\\"14.134275618374557%\\\"\\u003e\\n \\u003cp\\u003eClay\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 2.2034%;\\\" valign=\\\"bottom\\\" width=\\\"16.607773851590107%\\\"\\u003e\\n \\u003cp\\u003eSilt\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 3.1614%;\\\" valign=\\\"bottom\\\" width=\\\"16.607773851590107%\\\"\\u003e\\n \\u003cp\\u003eSand\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd style=\\\"width: 9.7717%;\\\" valign=\\\"bottom\\\" width=\\\"12.62295081967213%\\\"\\u003e\\n \\u003cp\\u003e0-20\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 4.9816%;\\\" valign=\\\"bottom\\\" width=\\\"6.229508196721311%\\\"\\u003e\\n \\u003cp\\u003e4.24\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 9.3885%;\\\" valign=\\\"bottom\\\" width=\\\"11.80327868852459%\\\"\\u003e\\n \\u003cp\\u003e0.80\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 9.7717%;\\\" valign=\\\"bottom\\\" width=\\\"12.295081967213115%\\\"\\u003e\\n \\u003cp\\u003e0.07\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 8.5263%;\\\" valign=\\\"bottom\\\" width=\\\"10.655737704918034%\\\"\\u003e\\n \\u003cp\\u003e0.02\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 12.7415%;\\\" valign=\\\"bottom\\\" width=\\\"7.704918032786885%\\\"\\u003e\\n \\u003cp\\u003e0.08\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 12.7415%;\\\" valign=\\\"bottom\\\" width=\\\"7.704918032786885%\\\"\\u003e\\n \\u003cp\\u003e0.42\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 9.6759%;\\\" valign=\\\"bottom\\\" width=\\\"9.01639344262295%\\\"\\u003e\\n \\u003cp\\u003e0.10\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 2.9698%;\\\" valign=\\\"bottom\\\" width=\\\"6.557377049180328%\\\"\\u003e\\n \\u003cp\\u003e18\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 2.2034%;\\\" valign=\\\"bottom\\\" width=\\\"7.704918032786885%\\\"\\u003e\\n \\u003cp\\u003e5.3\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 3.1614%;\\\" valign=\\\"bottom\\\" width=\\\"7.704918032786885%\\\"\\u003e\\n \\u003cp\\u003e76.2\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd style=\\\"width: 9.7717%;\\\" valign=\\\"bottom\\\" width=\\\"12.62295081967213%\\\"\\u003e\\n \\u003cp\\u003e20-40\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 4.9816%;\\\" valign=\\\"bottom\\\" width=\\\"6.229508196721311%\\\"\\u003e\\n \\u003cp\\u003e4.31\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 9.3885%;\\\" valign=\\\"bottom\\\" width=\\\"11.80327868852459%\\\"\\u003e\\n \\u003cp\\u003e0.50\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 9.7717%;\\\" valign=\\\"bottom\\\" width=\\\"12.295081967213115%\\\"\\u003e\\n \\u003cp\\u003e\\u0026lt;0.05\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 8.5263%;\\\" valign=\\\"bottom\\\" width=\\\"10.655737704918034%\\\"\\u003e\\n \\u003cp\\u003e0.01\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 12.7415%;\\\" valign=\\\"bottom\\\" width=\\\"7.704918032786885%\\\"\\u003e\\n \\u003cp\\u003e0.04\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 12.7415%;\\\" valign=\\\"bottom\\\" width=\\\"7.704918032786885%\\\"\\u003e\\n \\u003cp\\u003e0.37\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 9.6759%;\\\" valign=\\\"bottom\\\" width=\\\"9.01639344262295%\\\"\\u003e\\n \\u003cp\\u003e0.11\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 2.9698%;\\\" valign=\\\"bottom\\\" width=\\\"6.557377049180328%\\\"\\u003e\\n \\u003cp\\u003e18\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 2.2034%;\\\" valign=\\\"bottom\\\" width=\\\"7.704918032786885%\\\"\\u003e\\n \\u003cp\\u003e4.6\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 3.1614%;\\\" valign=\\\"bottom\\\" width=\\\"7.704918032786885%\\\"\\u003e\\n \\u003cp\\u003e77.3\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd style=\\\"width: 9.7717%;\\\" valign=\\\"bottom\\\" width=\\\"12.62295081967213%\\\"\\u003e\\n \\u003cp\\u003e40-60\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 4.9816%;\\\" valign=\\\"bottom\\\" width=\\\"6.229508196721311%\\\"\\u003e\\n \\u003cp\\u003e4.48\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 9.3885%;\\\" valign=\\\"bottom\\\" width=\\\"11.80327868852459%\\\"\\u003e\\n \\u003cp\\u003e0.50\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 9.7717%;\\\" valign=\\\"bottom\\\" width=\\\"12.295081967213115%\\\"\\u003e\\n \\u003cp\\u003e\\u0026lt;0.05\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 8.5263%;\\\" valign=\\\"bottom\\\" width=\\\"10.655737704918034%\\\"\\u003e\\n \\u003cp\\u003e\\u0026lt;0.01\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 12.7415%;\\\" valign=\\\"bottom\\\" width=\\\"7.704918032786885%\\\"\\u003e\\n \\u003cp\\u003e0.04\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 12.7415%;\\\" valign=\\\"bottom\\\" width=\\\"7.704918032786885%\\\"\\u003e\\n \\u003cp\\u003e0.50\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 9.6759%;\\\" valign=\\\"bottom\\\" width=\\\"9.01639344262295%\\\"\\u003e\\n \\u003cp\\u003e0.15\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 2.9698%;\\\" valign=\\\"bottom\\\" width=\\\"6.557377049180328%\\\"\\u003e\\n \\u003cp\\u003e-\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 2.2034%;\\\" valign=\\\"bottom\\\" width=\\\"7.704918032786885%\\\"\\u003e\\n \\u003cp\\u003e-\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 3.1614%;\\\" valign=\\\"bottom\\\" width=\\\"7.704918032786885%\\\"\\u003e\\n \\u003cp\\u003e-\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd style=\\\"width: 9.7717%;\\\" valign=\\\"bottom\\\" width=\\\"12.62295081967213%\\\"\\u003e\\n \\u003cp\\u003e60-80\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 4.9816%;\\\" valign=\\\"bottom\\\" width=\\\"6.229508196721311%\\\"\\u003e\\n \\u003cp\\u003e4.49\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 9.3885%;\\\" valign=\\\"bottom\\\" width=\\\"11.80327868852459%\\\"\\u003e\\n \\u003cp\\u003e0.50\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 9.7717%;\\\" valign=\\\"bottom\\\" width=\\\"12.295081967213115%\\\"\\u003e\\n \\u003cp\\u003e\\u0026lt;0.05\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 8.5263%;\\\" valign=\\\"bottom\\\" width=\\\"10.655737704918034%\\\"\\u003e\\n \\u003cp\\u003e\\u0026lt;0.01\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 12.7415%;\\\" valign=\\\"bottom\\\" width=\\\"7.704918032786885%\\\"\\u003e\\n \\u003cp\\u003e0.04\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 12.7415%;\\\" valign=\\\"bottom\\\" width=\\\"7.704918032786885%\\\"\\u003e\\n \\u003cp\\u003e0.50\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 9.6759%;\\\" valign=\\\"bottom\\\" width=\\\"9.01639344262295%\\\"\\u003e\\n \\u003cp\\u003e0.15\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 2.9698%;\\\" valign=\\\"bottom\\\" width=\\\"6.557377049180328%\\\"\\u003e\\n \\u003cp\\u003e-\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 2.2034%;\\\" valign=\\\"bottom\\\" width=\\\"7.704918032786885%\\\"\\u003e\\n \\u003cp\\u003e-\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 3.1614%;\\\" valign=\\\"bottom\\\" width=\\\"7.704918032786885%\\\"\\u003e\\n \\u003cp\\u003e-\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003c/tbody\\u003e\\n\\u003c/table\\u003e\\n\\u003cp\\u003e\\u0026delta;\\u003csup\\u003e15\\u003c/sup\\u003eN signatures of reference plants\\u003c/p\\u003e\\n\\u003cp\\u003eIn all the pruning dates, maize consistently recorded the highest mean \\u0026delta;\\u003csup\\u003e15\\u003c/sup\\u003eN in shoots as compared to \\u003cem\\u003eP. maximum.\\u003c/em\\u003e The overall mean \\u0026delta;\\u003csup\\u003e15\\u003c/sup\\u003eN value of these reference plants was used to estimate %Ndfa of pigeon pea and \\u003cem\\u003eS. sesban\\u003c/em\\u003e. In April, an overall reference plant \\u0026delta;\\u003csup\\u003e15\\u003c/sup\\u003eN value of +\\u0026thinsp;4.56\\u0026permil; was used to estimate the %Ndfa whereas the average mean \\u0026delta;\\u003csup\\u003e15\\u003c/sup\\u003eN values of +\\u0026thinsp;3.16\\u0026permil; and +\\u0026thinsp;3.27\\u0026permil; were used for estimating %Ndfa of the test woody species in November and February, respectively (Table \\u003cspan class=\\\"InternalRef\\\"\\u003e2\\u003c/span\\u003e).\\u0026nbsp;\\u003c/p\\u003e\\n\\u003cp\\u003eTable 2 Shoot \\u0026delta;\\u003csup\\u003e15\\u003c/sup\\u003eN (\\u0026permil;) values of reference plants sampled at different pruning dates\\u003c/p\\u003e\\n\\u003ctable border=\\\"1\\\" cellpadding=\\\"0\\\" cellspacing=\\\"0\\\" width=\\\"0\\\"\\u003e\\n \\u003ctbody\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd rowspan=\\\"2\\\" style=\\\"width: 16.3905%;\\\" width=\\\"16.44518272425249%\\\"\\u003e\\n \\u003cp\\u003eSampling date\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd rowspan=\\\"2\\\" style=\\\"width: 18.702%;\\\" width=\\\"21.92691029900332%\\\"\\u003e\\n \\u003cp\\u003eReference species\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd rowspan=\\\"2\\\" style=\\\"width: 18.5969%;\\\" width=\\\"14.451827242524917%\\\"\\u003e\\n \\u003cp\\u003eNumber of plants (\\u003cem\\u003en\\u003c/em\\u003e)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd colspan=\\\"3\\\" style=\\\"width: 38.4547%;\\\" width=\\\"35.548172757475086%\\\"\\u003e\\n \\u003cp\\u003e\\u0026delta;\\u003csup\\u003e15\\u003c/sup\\u003eN (\\u0026permil;)\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd style=\\\"width: 28.1581%;\\\" width=\\\"35.45816733067729%\\\"\\u003e\\n \\u003cp\\u003eRange\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 5.1483%;\\\" width=\\\"19.9203187250996%\\\"\\u003e\\n \\u003cp\\u003eMean\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 7.2497%;\\\" width=\\\"37.05179282868526%\\\"\\u003e\\n \\u003cp\\u003eOverall mean\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd style=\\\"width: 16.3905%;\\\" width=\\\"16.44518272425249%\\\"\\u003e\\n \\u003cp\\u003e\\u003cstrong\\u003ePre-treatment\\u003c/strong\\u003e\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 18.702%;\\\" width=\\\"21.92691029900332%\\\"\\u003e\\n \\u003cp\\u003e\\u0026nbsp;\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 18.5969%;\\\" width=\\\"14.451827242524917%\\\"\\u003e\\n \\u003cp\\u003e\\u0026nbsp;\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 28.1581%;\\\" width=\\\"14.784053156146179%\\\"\\u003e\\n \\u003cp\\u003e\\u0026nbsp;\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 5.1483%;\\\" width=\\\"8.305647840531561%\\\"\\u003e\\n \\u003cp\\u003e\\u0026nbsp;\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 7.2497%;\\\" width=\\\"15.448504983388704%\\\"\\u003e\\n \\u003cp\\u003e\\u0026nbsp;\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd style=\\\"width: 16.3905%;\\\" valign=\\\"bottom\\\" width=\\\"19.269102990033222%\\\"\\u003e\\n \\u003cp\\u003eApr-17\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 18.702%;\\\" valign=\\\"bottom\\\" width=\\\"21.92691029900332%\\\"\\u003e\\n \\u003cp\\u003e\\u003cem\\u003eP. maximum\\u003c/em\\u003e\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 18.5969%;\\\" valign=\\\"bottom\\\" width=\\\"20.26578073089701%\\\"\\u003e\\n \\u003cp\\u003e5\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 28.1581%;\\\" valign=\\\"bottom\\\" width=\\\"14.784053156146179%\\\"\\u003e\\n \\u003cp\\u003e3.58 \\u0026ndash; 3.93\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 5.1483%;\\\" valign=\\\"bottom\\\" width=\\\"8.305647840531561%\\\"\\u003e\\n \\u003cp\\u003e3.68\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 7.2497%;\\\" valign=\\\"bottom\\\" width=\\\"15.448504983388704%\\\"\\u003e\\u003cbr\\u003e\\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd style=\\\"width: 16.3905%;\\\" valign=\\\"bottom\\\" width=\\\"19.269102990033222%\\\"\\u003e\\u003cbr\\u003e\\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 18.702%;\\\" valign=\\\"bottom\\\" width=\\\"21.92691029900332%\\\"\\u003e\\n \\u003cp\\u003eMaize\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 18.5969%;\\\" valign=\\\"bottom\\\" width=\\\"20.26578073089701%\\\"\\u003e\\n \\u003cp\\u003e5\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 28.1581%;\\\" valign=\\\"bottom\\\" width=\\\"14.784053156146179%\\\"\\u003e\\n \\u003cp\\u003e5.31 \\u0026ndash; 6.01\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 5.1483%;\\\" valign=\\\"bottom\\\" width=\\\"8.305647840531561%\\\"\\u003e\\n \\u003cp\\u003e5.44\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 7.2497%;\\\" valign=\\\"bottom\\\" width=\\\"15.448504983388704%\\\"\\u003e\\u003cbr\\u003e\\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd style=\\\"width: 16.3905%;\\\" valign=\\\"bottom\\\" width=\\\"19.269102990033222%\\\"\\u003e\\u003cbr\\u003e\\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 18.702%;\\\" valign=\\\"bottom\\\" width=\\\"21.92691029900332%\\\"\\u003e\\u003cbr\\u003e\\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 18.5969%;\\\" valign=\\\"bottom\\\" width=\\\"20.26578073089701%\\\"\\u003e\\u003cbr\\u003e\\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 28.1581%;\\\" valign=\\\"bottom\\\" width=\\\"14.784053156146179%\\\"\\u003e\\n \\u003cp\\u003e\\u0026nbsp;\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 5.1483%;\\\" valign=\\\"bottom\\\" width=\\\"8.305647840531561%\\\"\\u003e\\u003cbr\\u003e\\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 7.2497%;\\\" valign=\\\"bottom\\\" width=\\\"15.448504983388704%\\\"\\u003e\\n \\u003cp\\u003e4.56\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd style=\\\"width: 16.3905%;\\\" valign=\\\"bottom\\\" width=\\\"19.269102990033222%\\\"\\u003e\\n \\u003cp\\u003e\\u003cstrong\\u003ePost-treatment\\u003c/strong\\u003e\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 18.702%;\\\" valign=\\\"bottom\\\" width=\\\"21.92691029900332%\\\"\\u003e\\n \\u003cp\\u003e\\u0026nbsp;\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 18.5969%;\\\" valign=\\\"bottom\\\" width=\\\"20.26578073089701%\\\"\\u003e\\n \\u003cp\\u003e\\u0026nbsp;\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 28.1581%;\\\" valign=\\\"bottom\\\" width=\\\"14.784053156146179%\\\"\\u003e\\n \\u003cp\\u003e\\u0026nbsp;\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 5.1483%;\\\" valign=\\\"bottom\\\" width=\\\"8.305647840531561%\\\"\\u003e\\n \\u003cp\\u003e\\u0026nbsp;\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 7.2497%;\\\" valign=\\\"bottom\\\" width=\\\"15.448504983388704%\\\"\\u003e\\n \\u003cp\\u003e\\u0026nbsp;\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd style=\\\"width: 16.3905%;\\\" valign=\\\"bottom\\\" width=\\\"19.269102990033222%\\\"\\u003e\\n \\u003cp\\u003eNov-17\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 18.702%;\\\" valign=\\\"bottom\\\" width=\\\"21.92691029900332%\\\"\\u003e\\n \\u003cp\\u003e\\u003cem\\u003eP. maximum\\u003c/em\\u003e\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 18.5969%;\\\" valign=\\\"bottom\\\" width=\\\"20.26578073089701%\\\"\\u003e\\n \\u003cp\\u003e9\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 28.1581%;\\\" valign=\\\"bottom\\\" width=\\\"14.784053156146179%\\\"\\u003e\\n \\u003cp\\u003e2.76 \\u0026ndash; 3.13\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 5.1483%;\\\" valign=\\\"bottom\\\" width=\\\"8.305647840531561%\\\"\\u003e\\n \\u003cp\\u003e2.91\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 7.2497%;\\\" valign=\\\"bottom\\\" width=\\\"15.448504983388704%\\\"\\u003e\\u003cbr\\u003e\\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd style=\\\"width: 16.3905%;\\\" valign=\\\"bottom\\\" width=\\\"19.269102990033222%\\\"\\u003e\\u003cbr\\u003e\\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 18.702%;\\\" valign=\\\"bottom\\\" width=\\\"21.92691029900332%\\\"\\u003e\\n \\u003cp\\u003eMaize\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 18.5969%;\\\" valign=\\\"bottom\\\" width=\\\"20.26578073089701%\\\"\\u003e\\n \\u003cp\\u003e9\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 28.1581%;\\\" valign=\\\"bottom\\\" width=\\\"14.784053156146179%\\\"\\u003e\\n \\u003cp\\u003e2.50- 4.80\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 5.1483%;\\\" valign=\\\"bottom\\\" width=\\\"8.305647840531561%\\\"\\u003e\\n \\u003cp\\u003e3.42\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 7.2497%;\\\" valign=\\\"bottom\\\" width=\\\"15.448504983388704%\\\"\\u003e\\u003cbr\\u003e\\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd style=\\\"width: 16.3905%;\\\" valign=\\\"bottom\\\" width=\\\"19.269102990033222%\\\"\\u003e\\u003cbr\\u003e\\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 18.702%;\\\" valign=\\\"bottom\\\" width=\\\"21.92691029900332%\\\"\\u003e\\u003cbr\\u003e\\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 18.5969%;\\\" valign=\\\"bottom\\\" width=\\\"20.26578073089701%\\\"\\u003e\\u003cbr\\u003e\\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 28.1581%;\\\" valign=\\\"bottom\\\" width=\\\"14.784053156146179%\\\"\\u003e\\n \\u003cp\\u003e\\u0026nbsp;\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 5.1483%;\\\" valign=\\\"bottom\\\" width=\\\"8.305647840531561%\\\"\\u003e\\u003cbr\\u003e\\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 7.2497%;\\\" valign=\\\"bottom\\\" width=\\\"15.448504983388704%\\\"\\u003e\\n \\u003cp\\u003e3.16\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd style=\\\"width: 16.3905%;\\\" valign=\\\"bottom\\\" width=\\\"19.269102990033222%\\\"\\u003e\\n \\u003cp\\u003eFeb-18\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 18.702%;\\\" valign=\\\"bottom\\\" width=\\\"21.92691029900332%\\\"\\u003e\\n \\u003cp\\u003e\\u003cem\\u003eP. maximum\\u003c/em\\u003e\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 18.5969%;\\\" valign=\\\"bottom\\\" width=\\\"20.26578073089701%\\\"\\u003e\\n \\u003cp\\u003e9\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 28.1581%;\\\" valign=\\\"bottom\\\" width=\\\"14.784053156146179%\\\"\\u003e\\n \\u003cp\\u003e2.59 \\u0026ndash; 3.18\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 5.1483%;\\\" valign=\\\"bottom\\\" width=\\\"8.305647840531561%\\\"\\u003e\\n \\u003cp\\u003e2.85\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 7.2497%;\\\" valign=\\\"bottom\\\" width=\\\"15.448504983388704%\\\"\\u003e\\u003cbr\\u003e\\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd style=\\\"width: 16.3905%;\\\" valign=\\\"bottom\\\" width=\\\"19.269102990033222%\\\"\\u003e\\u003cbr\\u003e\\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 18.702%;\\\" valign=\\\"bottom\\\" width=\\\"21.92691029900332%\\\"\\u003e\\n \\u003cp\\u003eMaize\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 18.5969%;\\\" valign=\\\"bottom\\\" width=\\\"20.26578073089701%\\\"\\u003e\\n \\u003cp\\u003e9\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 28.1581%;\\\" valign=\\\"bottom\\\" width=\\\"14.784053156146179%\\\"\\u003e\\n \\u003cp\\u003e2.82 \\u0026ndash; 5.18\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 5.1483%;\\\" valign=\\\"bottom\\\" width=\\\"8.305647840531561%\\\"\\u003e\\n \\u003cp\\u003e3.68\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 7.2497%;\\\" valign=\\\"bottom\\\" width=\\\"15.448504983388704%\\\"\\u003e\\u003cbr\\u003e\\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd style=\\\"width: 16.3905%;\\\" valign=\\\"bottom\\\" width=\\\"19.269102990033222%\\\"\\u003e\\n \\u003cp\\u003e\\u0026nbsp;\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 18.702%;\\\" valign=\\\"bottom\\\" width=\\\"21.92691029900332%\\\"\\u003e\\n \\u003cp\\u003e\\u003cem\\u003e\\u0026nbsp;\\u003c/em\\u003e\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 18.5969%;\\\" valign=\\\"bottom\\\" width=\\\"20.26578073089701%\\\"\\u003e\\n \\u003cp\\u003e\\u0026nbsp;\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 28.1581%;\\\" valign=\\\"bottom\\\" width=\\\"14.784053156146179%\\\"\\u003e\\n \\u003cp\\u003e\\u0026nbsp;\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 5.1483%;\\\" valign=\\\"bottom\\\" width=\\\"8.305647840531561%\\\"\\u003e\\n \\u003cp\\u003e\\u0026nbsp;\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd style=\\\"width: 7.2497%;\\\" valign=\\\"bottom\\\" width=\\\"15.448504983388704%\\\"\\u003e\\n \\u003cp\\u003e3.27\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003c/tbody\\u003e\\n\\u003c/table\\u003e\\n\\u003cp\\u003ePre-treatment symbiotic performance\\u003c/p\\u003e\\n\\u003cp \\u003eA 2-Way ANOVA on the pre-treatment data revealed no significant interaction between woody legume species and pruning management plots for %N, \\u0026delta;\\u003csup\\u003e15\\u003c/sup\\u003eN, %Ndfa, N\\u003csub\\u003e2\\u003c/sub\\u003e fixed and soil N uptake of test legume species (Table \\u003cspan class=\\\"InternalRef\\\"\\u003e3\\u003c/span\\u003e). Similarly, the main effect of pruning management plots on measured variables was not significant indicating that soil conditions of the study site were uniform prior to the imposition of experimental treatments. However, the main effect of species was significant for all measured variables. Foliar %N varied considerably among the legume species, with highest values recorded in pigeon pea compared with \\u003cem\\u003eS. sesban\\u003c/em\\u003e (Table \\u003cspan class=\\\"InternalRef\\\"\\u003e3\\u003c/span\\u003e).\\u003c/p\\u003e\\n\\u003cp \\u003ePigeon pea exhibited significantly lower \\u0026delta;\\u003csup\\u003e15\\u003c/sup\\u003eN values relative to \\u003cem\\u003eS. sesban\\u003c/em\\u003e. Because of the low \\u0026delta;\\u003csup\\u003e15\\u003c/sup\\u003eN values, %Ndfa estimates of pigeon pea were considerably higher as compared with those recorded for \\u003cem\\u003eS. sesban\\u003c/em\\u003e. The amounts of N\\u003csub\\u003e2\\u003c/sub\\u003e fixed were similarly greater in pigeon pea than \\u003cem\\u003eS. sesban.\\u003c/em\\u003e However, the amounts of soil N uptake were 4.1-fold higher in \\u003cem\\u003eS. sesban\\u003c/em\\u003e as compared with pigeon pea (Table \\u003cspan class=\\\"InternalRef\\\"\\u003e3\\u003c/span\\u003e).\\u003c/p\\u003e\\n\\u003ctable border=\\\"1\\\" id=\\\"Tab3\\\"\\u003e\\n \\u003ccaption language=\\\"En\\\"\\u003e\\n \\u003cdiv class=\\\"CaptionNumber\\\"\\u003eTable 3\\u003c/div\\u003e\\n \\u003cdiv class=\\\"CaptionContent\\\"\\u003e\\n \\u003cp\\u003eA 2-Way ANOVA of symbiotic performance (measured as 𝛿\\u003csup\\u003e15\\u003c/sup\\u003eN, %Ndfa, %N and N\\u003csub\\u003e2\\u003c/sub\\u003e fixed) and soil N uptake by pigeon pea and \\u003cem\\u003eS. sesban\\u003c/em\\u003e prior to imposition of experimental treatments (i.e. retained vs. removed). Data are means\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;standard error. Significant differences (p\\u0026thinsp;\\u0026lt;\\u0026thinsp;0.05) are indicated with dissimilar letters\\u003c/p\\u003e\\n \\u003c/div\\u003e\\n \\u003c/caption\\u003e\\n \\u003cthead\\u003e\\n \\u003ctr\\u003e\\n \\u003cth align=\\\"left\\\" rowspan=\\\"2\\\"\\u003e\\n \\u003cp\\u003eTreatment\\u003c/p\\u003e\\n \\u003c/th\\u003e\\n \\u003cth align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e\\u0026delta;\\u003csup\\u003e15\\u003c/sup\\u003eN\\u003c/p\\u003e\\n \\u003c/th\\u003e\\n \\u003cth align=\\\"left\\\"\\u003e\\n \\u003cp\\u003eNdfa\\u003c/p\\u003e\\n \\u003c/th\\u003e\\n \\u003cth align=\\\"left\\\"\\u003e\\n \\u003cp\\u003eN\\u003c/p\\u003e\\n \\u003c/th\\u003e\\n \\u003cth align=\\\"left\\\"\\u003e\\n \\u003cp\\u003eN\\u003csub\\u003e2\\u003c/sub\\u003e fixed\\u003c/p\\u003e\\n \\u003c/th\\u003e\\n \\u003cth align=\\\"left\\\"\\u003e\\n \\u003cp\\u003eSoil N uptake\\u003c/p\\u003e\\n \\u003c/th\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003cth align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e(\\u0026permil;)\\u003c/p\\u003e\\n \\u003c/th\\u003e\\n \\u003cth align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e%\\u003c/p\\u003e\\n \\u003c/th\\u003e\\n \\u003cth align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e%\\u003c/p\\u003e\\n \\u003c/th\\u003e\\n \\u003cth align=\\\"left\\\"\\u003e\\n \\u003cp\\u003ekg ha\\u003csup\\u003e\\u0026minus;\\u0026thinsp;1\\u003c/sup\\u003e\\u003c/p\\u003e\\n \\u003c/th\\u003e\\n \\u003cth align=\\\"left\\\"\\u003e\\n \\u003cp\\u003ekg ha\\u003csup\\u003e\\u0026minus;\\u0026thinsp;1\\u003c/sup\\u003e\\u003c/p\\u003e\\n \\u003c/th\\u003e\\n \\u003c/tr\\u003e\\n \\u003c/thead\\u003e\\n \\u003ctbody\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e\\u003cstrong\\u003eLegume species\\u003c/strong\\u003e\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd\\u003e\\u0026nbsp;\\u003c/td\\u003e\\n \\u003ctd\\u003e\\u0026nbsp;\\u003c/td\\u003e\\n \\u003ctd\\u003e\\u0026nbsp;\\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\u0026nbsp;\\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\u0026nbsp;\\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003ePigeon pea\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e-0.47\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.18b\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e89.4\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;2.7a\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e3.23\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.07a\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e48.0\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;2.4a\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e5.9\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;1.5b\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e\\u003cem\\u003eS. sesban\\u003c/em\\u003e\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e0.59\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.11a\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e62.9\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;1.7b\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e2.96\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.08b\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e38.2\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;1.6b\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e22.7\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;1.3a\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e\\u003cstrong\\u003ePruning management\\u003c/strong\\u003e\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\u0026nbsp;\\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\u0026nbsp;\\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\u0026nbsp;\\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\u0026nbsp;\\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\u0026nbsp;\\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003eRetain plots\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e0.08\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.16a\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e76.4\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;3.3a\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e3.14\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.07a\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e44.2\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;2.0a\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e14.5\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;2.1a\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003eRemove plots\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e0.03\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.20a\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e75.9\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;3.8a\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e3.04\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.09a\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e42.1\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;2.3a\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e14.1\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;2.4a\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e\\u003cstrong\\u003eF-statistics\\u003c/strong\\u003e\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\u0026nbsp;\\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\u0026nbsp;\\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\u0026nbsp;\\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\u0026nbsp;\\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\u0026nbsp;\\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003eSpecies\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e25.45***\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e66.9***\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e6.44*\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e13.0***\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e68.2***\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003ePruning management\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e0.05NS\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e0.1NS\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e0.84NS\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e0.6NS\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e0.1NS\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003eSpecies*pruning management\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e0.54NS\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e0.2NS\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e0.45NS\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e1.2NS\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e1.1NS\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003c/tbody\\u003e\\n\\u003c/table\\u003e\\n\\u003cp\\u003eEffect of retaining vs removing prunings on symbiotic performance\\u003c/p\\u003e\\n\\u003cp\\u003eThere was no significant interaction between species, pruning management and pruning date for %N, \\u0026delta;\\u003csup\\u003e15\\u003c/sup\\u003eN, %Ndfa, N\\u003csub\\u003e2\\u003c/sub\\u003e fixed and soil N uptake (Table \\u003cspan class=\\\"InternalRef\\\"\\u003e4\\u003c/span\\u003e). However, the was a significant interaction between species and pruning management for %N, %Ndfa and soil N uptake but not for 𝛿\\u003csup\\u003e15\\u003c/sup\\u003eN and N\\u003csub\\u003e2\\u003c/sub\\u003e-fixed. Except for %N, there was a significant interaction between species and pruning date for 𝛿\\u003csup\\u003e15\\u003c/sup\\u003eN, %Ndfa, N\\u003csub\\u003e2\\u003c/sub\\u003e-fixed and soil N uptake. There was a significant interaction between pruning management and pruning date for 𝛿\\u003csup\\u003e15\\u003c/sup\\u003eN, %Ndfa and soil N uptake but not for %N and N\\u003csub\\u003e2\\u003c/sub\\u003e-fixed (Table \\u003cspan class=\\\"InternalRef\\\"\\u003e4\\u003c/span\\u003e).\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cbr\\u003e\\u003c/p\\u003e\\n\\u003ctable border=\\\"1\\\" id=\\\"Tab4\\\"\\u003e\\n \\u003ccaption language=\\\"En\\\"\\u003e\\n \\u003cdiv class=\\\"CaptionNumber\\\"\\u003eTable 4\\u003c/div\\u003e\\n \\u003cdiv class=\\\"CaptionContent\\\"\\u003e\\n \\u003cp\\u003eSummary of a 3-Way ANOVA F-statistics on symbiotic performance of pigeon pea and \\u003cem\\u003eS. sesban\\u003c/em\\u003e plants as affected pruning management and pruning date\\u003c/p\\u003e\\n \\u003c/div\\u003e\\n \\u003c/caption\\u003e\\n \\u003cthead\\u003e\\n \\u003ctr\\u003e\\n \\u003cth align=\\\"left\\\" rowspan=\\\"2\\\"\\u003e\\n \\u003cp\\u003eSource of variation\\u003c/p\\u003e\\n \\u003c/th\\u003e\\n \\u003cth align=\\\"left\\\" rowspan=\\\"2\\\"\\u003e\\n \\u003cp\\u003edf\\u003c/p\\u003e\\n \\u003c/th\\u003e\\n \\u003cth align=\\\"left\\\"\\u003e\\n \\u003cp\\u003eN\\u003c/p\\u003e\\n \\u003c/th\\u003e\\n \\u003cth align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e𝛿\\u003csup\\u003e15\\u003c/sup\\u003eN\\u003c/p\\u003e\\n \\u003c/th\\u003e\\n \\u003cth align=\\\"left\\\"\\u003e\\n \\u003cp\\u003eNdfa\\u003c/p\\u003e\\n \\u003c/th\\u003e\\n \\u003cth align=\\\"left\\\"\\u003e\\n \\u003cp\\u003eN\\u003csub\\u003e2\\u003c/sub\\u003e-fixed\\u003c/p\\u003e\\n \\u003c/th\\u003e\\n \\u003cth align=\\\"left\\\"\\u003e\\n \\u003cp\\u003eSoil N\\u003c/p\\u003e\\n \\u003c/th\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003cth align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e%\\u003c/p\\u003e\\n \\u003c/th\\u003e\\n \\u003cth align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e(\\u0026permil;)\\u003c/p\\u003e\\n \\u003c/th\\u003e\\n \\u003cth align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e%\\u003c/p\\u003e\\n \\u003c/th\\u003e\\n \\u003cth align=\\\"left\\\" colspan=\\\"2\\\"\\u003e\\n \\u003cp\\u003ekg ha\\u003csup\\u003e\\u0026minus;\\u0026thinsp;1\\u003c/sup\\u003e\\u003c/p\\u003e\\n \\u003c/th\\u003e\\n \\u003c/tr\\u003e\\n \\u003c/thead\\u003e\\n \\u003ctbody\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd align=\\\"left\\\" colspan=\\\"2\\\"\\u003e\\n \\u003cp\\u003e\\u003cstrong\\u003eMain effects\\u003c/strong\\u003e\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\u0026nbsp;\\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\u0026nbsp;\\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\u0026nbsp;\\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\u0026nbsp;\\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\u0026nbsp;\\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003eSpecies\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e1\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e33.6***\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e636.9***\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e1206.5***\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e119.0***\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e457.2***\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003ePruning management\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e1\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e1.78NS\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e1757.9***\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e1709.0***\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e5.1*\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e67.4***\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003ePruning date\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e1\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e67.1***\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e140.3***\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e389.4**\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e130.1***\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e42.9***\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd align=\\\"left\\\" colspan=\\\"2\\\"\\u003e\\n \\u003cp\\u003e\\u003cstrong\\u003e2-Way interactions\\u003c/strong\\u003e\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\u0026nbsp;\\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\u0026nbsp;\\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\u0026nbsp;\\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\u0026nbsp;\\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\u0026nbsp;\\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003eSpecies*Pruning management\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e1\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e7.9**\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e2.0NS\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e6.3*\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e0.0NS\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e4.6*\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003eSpecies*Pruning date\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e1\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e0.1NS\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e3242.4***\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e3166.4***\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e113.5***\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e117.8***\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003ePruning man. *Pruning date\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e1\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e3.6NS\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e26.5***\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e29.7***\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e2.8NS\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e12.76***\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd align=\\\"left\\\" colspan=\\\"2\\\"\\u003e\\n \\u003cp\\u003e\\u003cstrong\\u003e3-Way interactions\\u003c/strong\\u003e\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\u0026nbsp;\\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\u0026nbsp;\\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\u0026nbsp;\\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\u0026nbsp;\\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\u0026nbsp;\\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003ctr\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003eSpecies*Pruning man. *Pruning date\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e1\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e0.4NS\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e2.3NS\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e0.9NS\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e0.2NS\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003ctd align=\\\"left\\\"\\u003e\\n \\u003cp\\u003e1.0NS\\u003c/p\\u003e\\n \\u003c/td\\u003e\\n \\u003c/tr\\u003e\\n \\u003c/tbody\\u003e\\n\\u003c/table\\u003e\\n\\u003cp\\u003eFor pigeon pea, removing fresh prunings significantly increased foliar %N by 9% compared to when prunings were not removed (Fig. \\u003cspan class=\\\"InternalRef\\\"\\u003e2\\u003c/span\\u003eA). In contrast, removing prunings decreased %N of \\u003cem\\u003eS. sesban\\u003c/em\\u003e by almost 3% as compared with when prunings were retained. Retaining fresh prunings on the soil surface significantly reduced %Ndfa of pigeon pea and \\u003cem\\u003eS. sesban\\u003c/em\\u003e by 18 and 29%, respectively (Fig. \\u003cspan class=\\\"InternalRef\\\"\\u003e2\\u003c/span\\u003eB). As compared with removing prunings, retaining prunings significantly increased soil N uptake by pigeon pea and \\u003cem\\u003eS. sesban\\u003c/em\\u003e (Fig. \\u003cspan class=\\\"InternalRef\\\"\\u003e2\\u003c/span\\u003eC).\\u003c/p\\u003e\\n\\u003cp\\u003eIn both pruning dates, pigeon pea exhibited significantly lower 𝛿\\u003csup\\u003e15\\u003c/sup\\u003eN values as compared with \\u003cem\\u003eS. sesban\\u003c/em\\u003e (Fig. \\u003cspan class=\\\"InternalRef\\\"\\u003e3\\u003c/span\\u003eA). As compared with \\u003cem\\u003eS. sesban\\u003c/em\\u003e, %Ndfa estimates of pigeon pea were significantly higher in November and February (Fig. \\u003cspan class=\\\"InternalRef\\\"\\u003e3\\u003c/span\\u003eB). Although the amount of N\\u003csub\\u003e2\\u003c/sub\\u003e fixed was similar for both legume species in November, pigeon pea recorded 2.8-fold higher amount of N\\u003csub\\u003e2\\u003c/sub\\u003e fixed as compared to \\u003cem\\u003eS. sesban\\u003c/em\\u003e in February (Fig. \\u003cspan class=\\\"InternalRef\\\"\\u003e3\\u003c/span\\u003eC). Compared with pigeon pea, \\u003cem\\u003eS. sesban\\u003c/em\\u003e recorded 2.2-fold and 7.7-fold higher amount of soil N uptake in November and February, respectively (Fig. \\u003cspan class=\\\"InternalRef\\\"\\u003e3\\u003c/span\\u003eD).\\u003c/p\\u003e\\n\\u003cp\\u003eWhether prunings were removed or retained, the 𝛿\\u003csup\\u003e15\\u003c/sup\\u003eN values were significantly higher in November 2017 as compared with February 2018 (Fig. \\u003cspan class=\\\"InternalRef\\\"\\u003e4\\u003c/span\\u003eA). Surface retention of green prunings increased, on average, 𝛿\\u003csup\\u003e15\\u003c/sup\\u003eN values as compared to when prunings were removed. The %Ndfa estimates were higher in February as compared to November (Fig. \\u003cspan class=\\\"InternalRef\\\"\\u003e4\\u003c/span\\u003eB). %Ndfa values were, on average, decreased by retention of tree prunings as compared to their removal. Whether prunings were removed or retained the amount of soil N uptake was significantly lower in November as compared with February (Fig. \\u003cspan class=\\\"InternalRef\\\"\\u003e4\\u003c/span\\u003eC). Soil N uptake values were, on average, increased by retention of tree prunings as compared to their removal.\\u003c/p\\u003e\"},{\"header\":\"Discussion\",\"content\":\"\\u003cp\\u003eShoot \\u0026#120575;\\u003csup\\u003e15\\u003c/sup\\u003eN of reference plants\\u003c/p\\u003e \\u003cp\\u003eThis study assessed the effect of retention versus removal of green prunings on symbiotic N\\u003csub\\u003e2\\u003c/sub\\u003e fixation of \\u003cem\\u003eS. sesban\\u003c/em\\u003e and pigeon pea using the \\u003csup\\u003e15\\u003c/sup\\u003eN natural abundance technique. With this method, the choice of a suitable reference plant, which is assumed to represent a measure of isotopic signature of plant available soil N for the target N\\u003csub\\u003e2\\u003c/sub\\u003e-fixing plant, is of important consideration (Unkovich et al. 2008). The use of more than one non-N\\u003csub\\u003e2\\u003c/sub\\u003e-fixing reference species, especially cereal or grass, is also highly recommended for improving the accuracy of N\\u003csub\\u003e2\\u003c/sub\\u003e fixation estimates (Unkovich et al. 2008). In this study \\u003cem\\u003eP. maximum\\u003c/em\\u003e and maize were used as reference species, and the latter species consistently exhibited greater shoot \\u0026#120575;\\u003csup\\u003e15\\u003c/sup\\u003eN values across the pruning dates (Table\\u0026nbsp;\\u003cspan refid=\\\"Tab2\\\" class=\\\"InternalRef\\\"\\u003e2\\u003c/span\\u003e). The variation in shoot δ\\u003csup\\u003e15\\u003c/sup\\u003eN of the reference plants used in this study is indicative of inherent differences in isotopic discrimination among the species, or differences in soil N uptake patterns due to varying root phenology and volume of soil explored. Relative to foliar \\u0026#120575;\\u003csup\\u003e15\\u003c/sup\\u003eN values of woody species, the shoot \\u0026#120575;\\u003csup\\u003e15\\u003c/sup\\u003eN range of reference plants was sufficiently large to provide reliable estimates of symbiotic N\\u003csub\\u003e2\\u003c/sub\\u003e fixation by the \\u003csup\\u003e15\\u003c/sup\\u003eN natural abundance method.\\u003c/p\\u003e \\u003cp\\u003ePre-treatment symbiotic performance of test legumes\\u003c/p\\u003e \\u003cp\\u003eThe strong variation in δ\\u003csup\\u003e15\\u003c/sup\\u003eN values between the reference plants and test legume species strongly indicate that pigeon pea and \\u003cem\\u003eS. sesban\\u003c/em\\u003e relied mainly on symbiotic N\\u003csub\\u003e2\\u003c/sub\\u003e fixation to satisfy their N requirements (Tables\\u0026nbsp;\\u003cspan refid=\\\"Tab2\\\" class=\\\"InternalRef\\\"\\u003e2\\u003c/span\\u003e and \\u003cspan refid=\\\"Tab3\\\" class=\\\"InternalRef\\\"\\u003e3\\u003c/span\\u003e), which allowed for reliable assessment of pruning management effects on N\\u003csub\\u003e2\\u003c/sub\\u003e fixation of the test species. Similar to what has been reported in a previous study (Chikowo et al. \\u003cspan citationid=\\\"CR3\\\" class=\\\"CitationRef\\\"\\u003e2004\\u003c/span\\u003e), pigeon pea exhibited significantly lower δ\\u003csup\\u003e15\\u003c/sup\\u003eN values and consequently higher %Ndfa values as compared to \\u003cem\\u003eS. sesban\\u003c/em\\u003e (Table\\u0026nbsp;\\u003cspan refid=\\\"Tab3\\\" class=\\\"InternalRef\\\"\\u003e3\\u003c/span\\u003e). The mean %Ndfa estimates were 89 and 63% for pigeon pea and \\u003cem\\u003eS. sesban\\u003c/em\\u003e, respectively, and are within the range of previous reports on pigeon pea symbiotic performance in Zimbabwe (58\\u0026ndash;100%; Mapfumo et al. \\u003cspan citationid=\\\"CR18\\\" class=\\\"CitationRef\\\"\\u003e1999\\u003c/span\\u003e) or in South Africa (27\\u0026ndash;92%; Dakora et al. \\u003cspan citationid=\\\"CR6\\\" class=\\\"CitationRef\\\"\\u003e2015\\u003c/span\\u003e) and on \\u003cem\\u003eS. sesban\\u003c/em\\u003e N\\u003csub\\u003e2\\u003c/sub\\u003e fixation in Zimbabwe (42\\u0026ndash;73%; Chikowo et al. \\u003cspan citationid=\\\"CR3\\\" class=\\\"CitationRef\\\"\\u003e2004\\u003c/span\\u003e) assessed using the \\u003csup\\u003e15\\u003c/sup\\u003eN natural abundance technique. Although the test species were established without assessing the presence of microsymbionts capable of forming N\\u003csub\\u003e2\\u003c/sub\\u003e-fixing nodules, the higher %Ndfa values obtained in this study confirmed that pigeon pea and \\u003cem\\u003eS. sesban\\u003c/em\\u003e adapted well to the conditions of the study site, and that both species were able to form a highly functional symbiosis in association with native rhizobia population.\\u003c/p\\u003e \\u003cp\\u003ePigeon pea recorded considerably higher %N and amount of N\\u003csub\\u003e2\\u003c/sub\\u003e fixed as compared with \\u003cem\\u003eS. sesban\\u003c/em\\u003e (Table\\u0026nbsp;\\u003cspan refid=\\\"Tab3\\\" class=\\\"InternalRef\\\"\\u003e3\\u003c/span\\u003e). The aerial biomass of pigeon pea and \\u003cem\\u003eS. sesban\\u003c/em\\u003e contained 27\\u0026ndash;66 kg ha\\u003csup\\u003e\\u0026minus;\\u0026thinsp;1\\u003c/sup\\u003e and 22\\u0026ndash;54 kg ha\\u003csup\\u003e\\u0026minus;\\u0026thinsp;1\\u003c/sup\\u003e of N, respectively, thus indicating that they could be suitable for use as sources of green manure or fodder for livestock. Previous studies in agroforestry systems showed that \\u003cem\\u003eGliricidia sepium\\u003c/em\\u003e could accumulate 35 kg ha\\u003csup\\u003e\\u0026minus;\\u0026thinsp;1\\u003c/sup\\u003e (Hairiah et al. \\u003cspan citationid=\\\"CR9\\\" class=\\\"CitationRef\\\"\\u003e2000\\u003c/span\\u003e) and 31.4 to 38.0 kg ha\\u003csup\\u003e\\u0026minus;\\u0026thinsp;1\\u003c/sup\\u003e (Kaba et al. \\u003cspan citationid=\\\"CR13\\\" class=\\\"CitationRef\\\"\\u003e2019\\u003c/span\\u003e) of N in pruning biomass whilst species such as \\u003cem\\u003eFlemingia conjesta\\u003c/em\\u003e was shown to fix about 26 kg N ha\\u003csup\\u003e\\u0026minus;\\u0026thinsp;1\\u003c/sup\\u003e (Hairiah et al. \\u003cspan citationid=\\\"CR9\\\" class=\\\"CitationRef\\\"\\u003e2000\\u003c/span\\u003e). The amount of N\\u003csub\\u003e2\\u003c/sub\\u003e fixed in prunings obtained in these earlier studies are well within the range of the findings of this current study. \\u003cem\\u003eS. sesban\\u003c/em\\u003e had higher reliance on soil N as compared with pigeon pea suggesting that the vigorous growth nature of \\u003cem\\u003eS. sesban\\u003c/em\\u003e could have induced greater N demand which was unmet through symbiotic N\\u003csub\\u003e2\\u003c/sub\\u003e fixation. Therefore, that N deficit was obtained through increased sub-soil N capture. Chikowo et al. (\\u003cspan citationid=\\\"CR3\\\" class=\\\"CitationRef\\\"\\u003e2004\\u003c/span\\u003e) also showed that \\u003cem\\u003eS. sesban\\u003c/em\\u003e took up considerable amount of N from the soil when compared with pigeon pea.\\u003c/p\\u003e \\u003cp\\u003eEffects of retaining vs removing prunings on symbiotic performance\\u003c/p\\u003e \\u003cp\\u003eFoliar mean %N differed considerably among the test species (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig2\\\" class=\\\"InternalRef\\\"\\u003e2\\u003c/span\\u003eA), with greater values in \\u003cem\\u003eS. sesban\\u003c/em\\u003e relative to pigeon pea, thus highlighting inherent variation in rooting phenology and N uptake patterns among the test species (Palm et al. \\u003cspan citationid=\\\"CR20\\\" class=\\\"CitationRef\\\"\\u003e2001\\u003c/span\\u003e). Because \\u003cem\\u003eS. sesban\\u003c/em\\u003e achieves more rapid stem and leaf growth compared to pigeon pea (Chirwa et al. \\u003cspan citationid=\\\"CR4\\\" class=\\\"CitationRef\\\"\\u003e2004\\u003c/span\\u003e; Lemage et al. \\u003cspan citationid=\\\"CR15\\\" class=\\\"CitationRef\\\"\\u003e2021\\u003c/span\\u003e), the greater %N in the leaves could be due to greater root development (Lemage et al. \\u003cspan citationid=\\\"CR15\\\" class=\\\"CitationRef\\\"\\u003e2021\\u003c/span\\u003e). This probably enabled it to explore greater soil volumes and take up greater soil N to augment N deficit from symbiotically fixed N.\\u003c/p\\u003e \\u003cp\\u003eThe results of this study show that higher accumulation of soil N due to the decomposition of prunings inhibits symbiotic N\\u003csub\\u003e2\\u003c/sub\\u003e fixation of pigeon pea and \\u003cem\\u003eS. sesban\\u003c/em\\u003e. Lower %Ndfa estimates of test species were consistently recorded when fresh prunings were retained on the soil surface compared to when they were removed (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig2\\\" class=\\\"InternalRef\\\"\\u003e2\\u003c/span\\u003eB). Pigeon pea and \\u003cem\\u003eS. sesban\\u003c/em\\u003e prunings are high-quality organic inputs (high N but low lignin and polyphenol contents) capable of releasing nutrients into the soil rapidly (Mafongoya et al. \\u003cspan citationid=\\\"CR17\\\" class=\\\"CitationRef\\\"\\u003e1998\\u003c/span\\u003e). The inhibition of symbiotic N\\u003csub\\u003e2\\u003c/sub\\u003e fixation following retention of prunings is most likely due to increased mineralized N levels in the root zone of these species. As tree litters are mineralized, the amount of available N in the soil increases with time, this process leading to the cessation of N\\u003csub\\u003e2\\u003c/sub\\u003e fixation in aging plantations (Dommergues 1995). Kadiata et al. (\\u003cspan citationid=\\\"CR14\\\" class=\\\"CitationRef\\\"\\u003e1998\\u003c/span\\u003e) showed that the incorporation of tree prunings into soil significantly reduced the %Ndfa of \\u003cem\\u003eGliricidia sepium\\u003c/em\\u003e and \\u003cem\\u003eLeucaena leucocephala\\u003c/em\\u003e by 17 and 22%, respectively, as compared with when prunings were removed. The results indicate that the benefits from symbiotic N\\u003csub\\u003e2\\u003c/sub\\u003e fixation in agroforestry systems can be offset by the amount of N released from tree prunings or residues.\\u003c/p\\u003e \\u003cp\\u003eSoil N uptake by pigeon pea and \\u003cem\\u003eS. sesban\\u003c/em\\u003e was significantly increased by retention of prunings compared to their removal (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig2\\\" class=\\\"InternalRef\\\"\\u003e2\\u003c/span\\u003eC), and this could be attributable to the decrease in nodule functioning and N\\u003csub\\u003e2\\u003c/sub\\u003e fixation rates associated with elevated levels of N in the root zone of plants. Because N\\u003csub\\u003e2\\u003c/sub\\u003e fixation is an energy demanding process, greater reliance on soil N uptake could mean that the N satiety of the species was unmet through decreased N\\u003csub\\u003e2\\u003c/sub\\u003e fixation rates. The preferential uptake and assimilation of soil mineral N for meeting N satiety over fixing atmospheric N\\u003csub\\u003e2\\u003c/sub\\u003e is common in woody legumes (Dommergues 1995).\\u003c/p\\u003e \\u003cp\\u003ePigeon pea exhibited significantly lower δ\\u003csup\\u003e15\\u003c/sup\\u003eN compared with \\u003cem\\u003eS. sesban\\u003c/em\\u003e in both November 2017 and February 2018 (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig3\\\" class=\\\"InternalRef\\\"\\u003e3\\u003c/span\\u003eA). Consequently, pigeon derived a greater proportion of its N nutrition from symbiotic N\\u003csub\\u003e2\\u003c/sub\\u003e fixation compared with \\u003cem\\u003eS. sesban\\u003c/em\\u003e (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig3\\\" class=\\\"InternalRef\\\"\\u003e3\\u003c/span\\u003eB). The reliance on N\\u003csub\\u003e2\\u003c/sub\\u003e fixation (%Ndfa) ranged from 54\\u0026ndash;100% and 27\\u0026ndash;57% for pigeon pea and \\u003cem\\u003eS. sesban\\u003c/em\\u003e, respectively. The efficiency of N\\u003csub\\u003e2\\u003c/sub\\u003e-fixing activity between soil rhizobia and legumes is known to vary among species (Peoples et al. 2009). The superiority of pigeon pea over \\u003cem\\u003eS. sesban\\u003c/em\\u003e in terms of symbiotic performance could be attributable to its high symbiotic promiscuity (Vanlauwe et al. \\u003cspan citationid=\\\"CR28\\\" class=\\\"CitationRef\\\"\\u003e2019\\u003c/span\\u003e), and most likely, the presence of high population of compatible native soil rhizobia with greater N\\u003csub\\u003e2\\u003c/sub\\u003e-fixing efficiency in the study site. Chikowo et al. (\\u003cspan citationid=\\\"CR3\\\" class=\\\"CitationRef\\\"\\u003e2004\\u003c/span\\u003e) also reported considerably higher %Ndfa estimates in pigeon pea as compared with \\u003cem\\u003eS. sesban\\u003c/em\\u003e in improved fallow experiment in Zimbabwe. Due to higher %Ndfa values and most likely biomass, especially in February, pigeon pea accumulated significantly greater amounts of N\\u003csub\\u003e2\\u003c/sub\\u003e-fixed compared to \\u003cem\\u003eS. sesban\\u003c/em\\u003e (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig3\\\" class=\\\"InternalRef\\\"\\u003e3\\u003c/span\\u003ec). \\u003cem\\u003eS. sesban\\u003c/em\\u003e took up significantly higher soil N compared to pigeon.\\u003c/p\\u003e \\u003cp\\u003eLower δ\\u003csup\\u003e15\\u003c/sup\\u003eN and hence higher %Ndfa values were recorded in February 2018 as compared with November 2017 (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig4\\\" class=\\\"InternalRef\\\"\\u003e4\\u003c/span\\u003eA and \\u003cb\\u003eB\\u003c/b\\u003e) could be as a result of moisture stress and lower biomass at the end of the dry season (November). Environmental factors such as drought and extreme temperatures are known to impact growth and symbiotic functioning of nodulated legumes (Hungria and Vargas \\u003cspan citationid=\\\"CR11\\\" class=\\\"CitationRef\\\"\\u003e2000\\u003c/span\\u003e). Nitrogenase activity has been shown to decrease at low soil moisture levels, probably due to limited supply of C assimilates to the N\\u003csub\\u003e2\\u003c/sub\\u003e-fixing nodules (Hungria and Vargas \\u003cspan citationid=\\\"CR11\\\" class=\\\"CitationRef\\\"\\u003e2000\\u003c/span\\u003e; Chaves et al. 2009) or reduced N demand by plants. Nygren and Leblanc (2009) also found that \\u003cem\\u003eG. sepium\\u003c/em\\u003e trees derived a greater proportion of their N nutrition from symbiotic N\\u003csub\\u003e2\\u003c/sub\\u003e fixation in the rainy season as compared with the dry season when water availability in the soil was limiting.\\u003c/p\\u003e\"},{\"header\":\"Conclusion\",\"content\":\"\\u003cp\\u003eThe findings of this study demonstrated that the tested N\\u003csub\\u003e2\\u003c/sub\\u003e-fixing legumes adapted well to the conditions of the study site, and both species obtained more than 60% of their N nutrition from N\\u003csub\\u003e2\\u003c/sub\\u003e fixation prior to imposition of treatments. Retaining fresh prunings on the soil surface significantly depressed N\\u003csub\\u003e2\\u003c/sub\\u003e fixation rates of pigeon pea and \\u003cem\\u003eS. sesban\\u003c/em\\u003e. Additionally, retaining prunings also increased reliance of both species on soil mineral N. The effect of retaining prunings on N\\u003csub\\u003e2\\u003c/sub\\u003e fixation can be lessened only if N supply from prunings of N\\u003csub\\u003e2\\u003c/sub\\u003e-fixing woody legumes is synchronized with N demand of associated plants. Reasonable benefits in terms of net N additions to an agroforestry system N balance are likely to be achieved by maximising rates of N\\u003csub\\u003e2\\u003c/sub\\u003e fixation by removing freshly pruned material from the system. Therefore, in smallholder mixed crop-lived stock farming system in Africa it would be more practical to prune woody legumes and retaining in the fields as the source of organic matter and mineral nutrients, especially N for accumulation in the soil. To avoid N accumulation, which will reduce N\\u003csub\\u003e2\\u003c/sub\\u003e fixation, it would be practical in mixed crop -livestock farming systems, to only retain prunings during the cropping season when the demand for growing plants is high. Any material pruned during the dry season should be fed to livestock and not retained on the soil surface in the field.\\u003c/p\\u003e\"},{\"header\":\"Declarations\",\"content\":\"\\u003cp\\u003e\\u003cstrong\\u003eAcknowledgements\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eThe authors are thankful to Fountainhill Estate Farm for the provision of the study site and Dr Grant Hall at University of Pretoria, South Africa, for \\u003csup\\u003e15\\u003c/sup\\u003eN natural abundance analyses. Financial support from the Water Research Commission of South Africa under project number K5/2492//4 titled \\u0026lsquo;Water use of agroforestry systems for food, forage and/or biofuel production\\u0026rsquo; is gratefully acknowledged. Makhubedu I.T is grateful for a competitive doctoral scholarship from the National Research Foundation of South Africa (101500).\\u003c/p\\u003e\\n\\u003cp\\u003eFunding\\u003c/p\\u003e\\n\\u003cp\\u003eThis work was supported by the Water Research Commission of South Africa under project number K5/2492//4 titled \\u0026lsquo;Water use of agroforestry systems for food, forage and/or biofuel production\\u0026rsquo;. Makhubedu I.T received a scholarship from the National Research Foundation of South Africa (101500).\\u003c/p\\u003e\\n\\u003cp\\u003e\\u0026nbsp;Competing Interests\\u003c/p\\u003e\\n\\u003cp\\u003eAuthors declare they have no financial interests.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u0026nbsp;Author Contributions\\u003c/p\\u003e\\n\\u003cp\\u003eAll authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Makhubedu IT and Letty BA. The first draft of the manuscript was written by Makhubedu IT and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u0026nbsp;Data availability\\u003c/p\\u003e\\n\\u003cp\\u003eThe datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request.\\u003c/p\\u003e\"},{\"header\":\"References\",\"content\":\"\\u003col\\u003e\\n \\u003cli\\u003eBarnard RO, Du Preez CC (2004) Soil fertility in South Africa: the last twenty-five years.\\u0026nbsp;\\u003cem\\u003eS Afr J\\u0026nbsp;Plant Soil\\u003c/em\\u003e 21: 301-15.\\u0026nbsp;\\u003c/li\\u003e\\n \\u003cli\\u003eChen B, Liu E, Tian Q, Yan C, Zhang Y (2014) Soil nitrogen dynamics and crop residues. 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Environ\\u003c/em\\u003e 83: 27\\u0026ndash;42.\\u0026nbsp;\\u003c/li\\u003e\\n \\u003cli\\u003ePeoples MB, Faizah AW, Rerkasem B, Herridge DH (1989) Methods of evaluating nitrogen fixation by nodulated legumes in the field. Australian Centre for International Agricultural Research, Canberra.\\u003c/li\\u003e\\n \\u003cli\\u003eSanchez PA (2002) Soil fertility and hunger in Africa. \\u003cem\\u003eScience\\u003c/em\\u003e 295: 2019\\u0026ndash;20.\\u003c/li\\u003e\\n \\u003cli\\u003eShearer G, Kohl DH (1986) N2-fixation in field settings: estimations based on natural \\u003csup\\u003e15\\u003c/sup\\u003eN abundance.\\u0026nbsp;\\u003cem\\u003eFunct. Plant Biol\\u003c/em\\u003e 13: 699\\u0026ndash;756.\\u0026nbsp;\\u003c/li\\u003e\\n \\u003cli\\u003eSosibo NZ, Muchaonyerwa P, Visser L, Barnard A, Dube E, Tsilo TJ (2017) Soil fertility constraints and yield gaps of irrigation wheat in South Africa.\\u0026nbsp;\\u003cem\\u003eS.\\u0026nbsp;Afr.\\u0026nbsp;J.\\u0026nbsp;Sci\\u003c/em\\u003e 113: 1\\u0026ndash;9.\\u0026nbsp;\\u003c/li\\u003e\\n \\u003cli\\u003eSouth African Sugar Association (SASA) Weatherweb http://portal.sasa.org.za/weatherweb/. Accessed 17 June 2019.\\u003c/li\\u003e\\n \\u003cli\\u003eTongwane M, Mdlambuzi T, Moeletsi M, Tsubo M, Mliswa V, Grootboom L (2016) Greenhouse gas emissions from different crop production and management practices in South Africa.\\u0026nbsp;\\u003cem\\u003eEnviron. Dev\\u003c/em\\u003e 19: 23\\u0026ndash;35.\\u0026nbsp;\\u003c/li\\u003e\\n \\u003cli\\u003eUnkovich M (2012) Nitrogen fixation in Australian dairy systems: review and prospect. \\u003cem\\u003eCrop Pasture Sci\\u003c/em\\u003e 63: 787-804.\\u0026nbsp;\\u003c/li\\u003e\\n \\u003cli\\u003eVanlauwe B, Hungria M, Kanampiu F, Giller KE (2019) The role of legumes in the sustainable intensification of African smallholder agriculture: Lessons learnt and challenges for the future. \\u003cem\\u003eAgric. Ecosyst. Environ\\u003c/em\\u003e 284: 106583.\\u0026nbsp;\\u003c/li\\u003e\\n \\u003cli\\u003eYoukhana A, Idol T (2009) Tree pruning mulch increases soil C and N in a shaded coffee agroecosystem in Hawaii. \\u003cem\\u003eSoil Biol. Biochem\\u003c/em\\u003e 41: 2527\\u0026ndash;34.\\u003c/li\\u003e\\n\\u003c/ol\\u003e\"}],\"fulltextSource\":\"\",\"fullText\":\"\",\"funders\":[],\"hasAdminPriorityOnWorkflow\":false,\"hasManuscriptDocX\":true,\"hasOptedInToPreprint\":true,\"hasPassedJournalQc\":\"\",\"hasAnyPriority\":false,\"hideJournal\":false,\"highlight\":\"\",\"institution\":\"\",\"isAcceptedByJournal\":false,\"isAuthorSuppliedPdf\":false,\"isDeskRejected\":\"\",\"isHiddenFromSearch\":false,\"isInQc\":false,\"isInWorkflow\":false,\"isPdf\":false,\"isPdfUpToDate\":true,\"isWithdrawnOrRetracted\":false,\"journal\":{\"display\":true,\"email\":\"info@researchsquare.com\",\"identity\":\"plant-and-soil\",\"isNatureJournal\":false,\"hasQc\":true,\"allowDirectSubmit\":false,\"externalIdentity\":\"plso\",\"sideBox\":\"Learn more about [Plant and Soil](https://www.springer.com/journal/11104)\",\"snPcode\":\"11104\",\"submissionUrl\":\"https://submission.nature.com/new-submission/11104/3\",\"title\":\"Plant and Soil\",\"twitterHandle\":\"\",\"acdcEnabled\":true,\"dfaEnabled\":true,\"editorialSystem\":\"em\",\"reportingPortfolio\":\"Springer Hybrid\",\"inReviewEnabled\":true,\"inReviewRevisionsEnabled\":false},\"keywords\":\"Pigeon pea, Sesbania, 15N natural abundance, N2 fixation, Prunings, Agroforestry\",\"lastPublishedDoi\":\"10.21203/rs.3.rs-1798187/v1\",\"lastPublishedDoiUrl\":\"https://doi.org/10.21203/rs.3.rs-1798187/v1\",\"license\":{\"name\":\"CC BY 4.0\",\"url\":\"https://creativecommons.org/licenses/by/4.0/\"},\"manuscriptAbstract\":\"\\u003ch2\\u003eAim\\u003c/h2\\u003e \\u003cp\\u003eTo compare the effects of retention versus removal of green prunings on symbiotic N\\u003csub\\u003e2\\u003c/sub\\u003e fixation of \\u003cem\\u003eSesbania sesban\\u003c/em\\u003e and pigeon pea (\\u003cem\\u003eCajanus cajan\\u003c/em\\u003e).\\u003c/p\\u003e\\u003ch2\\u003eMethods\\u003c/h2\\u003e \\u003cp\\u003eA factorial experiment was conducted to evaluate the effects of retention versus removal of prunings on N\\u003csub\\u003e2\\u003c/sub\\u003e fixation of pigeon pea and \\u003cem\\u003eS. sesban\\u003c/em\\u003e. The plots had three rows of woody legumes, and \\u003cem\\u003eZea mays\\u003c/em\\u003e (maize) was planted in between the legume rows. Three prunings were conducted between April 2017 and February 2018 by cutting the legumes back to 75 cm height. Pruned leaves and twigs were either spread evenly (retained) on the soil surface or completely removed (removed). N\\u003csub\\u003e2\\u003c/sub\\u003e fixation was measured using the \\u003csup\\u003e15\\u003c/sup\\u003eN natural abundance method.\\u003c/p\\u003e\\u003ch2\\u003eResults\\u003c/h2\\u003e \\u003cp\\u003eWhether fresh prunings were retained or removed, pigeon pea derived a significant proportion of its N nutrition from N\\u003csub\\u003e2\\u003c/sub\\u003e fixation as compared with \\u003cem\\u003eS. sesban\\u003c/em\\u003e. Retaining prunings on the soil surface significantly depressed symbiotic N\\u003csub\\u003e2\\u003c/sub\\u003e fixation by 18% in pigeon pea and 20.6% in \\u003cem\\u003eS. sesban\\u003c/em\\u003e compared to when prunings were removed. The results also showed that retaining prunings increased the reliance of pigeon pea and \\u003cem\\u003eS. sesban\\u003c/em\\u003e on soil N uptake.\\u003c/p\\u003e\\u003ch2\\u003eConclusions\\u003c/h2\\u003e \\u003cp\\u003eRetaining both leaves and twigs in agroforestry systems reduces N\\u003csub\\u003e2\\u003c/sub\\u003e fixation by pigeon pea and \\u003cem\\u003eS. sesban\\u003c/em\\u003e. The observed reduction in N\\u003csub\\u003e2\\u003c/sub\\u003e fixation following retention of prunings could diminish the beneficial effects of N\\u003csub\\u003e2\\u003c/sub\\u003e-fixing species on soil N fertility in agroforestry systems.\\u003c/p\\u003e\",\"manuscriptTitle\":\"Effect of retaining versus removing green prunings on N2 fixation of Cajanus cajan and Sesbania sesban\",\"msid\":\"\",\"msnumber\":\"\",\"nonDraftVersions\":[{\"code\":1,\"date\":\"2022-07-19 18:44:34\",\"doi\":\"10.21203/rs.3.rs-1798187/v1\",\"editorialEvents\":[{\"type\":\"communityComments\",\"content\":0},{\"type\":\"decision\",\"content\":\"Major revisions\",\"date\":\"2022-08-25T16:02:46+00:00\",\"index\":\"\",\"fulltext\":\"\"},{\"type\":\"reviewerAgreed\",\"content\":\"\",\"date\":\"2022-07-05T05:41:44+00:00\",\"index\":0,\"fulltext\":\"\"},{\"type\":\"reviewersInvited\",\"content\":\"\",\"date\":\"2022-07-04T10:02:12+00:00\",\"index\":\"\",\"fulltext\":\"\"},{\"type\":\"editorInvited\",\"content\":\"Plant and Soil\",\"date\":\"2022-07-04T02:03:24+00:00\",\"index\":\"\",\"fulltext\":\"\"},{\"type\":\"editorAssigned\",\"content\":\"\",\"date\":\"2022-07-04T01:13:22+00:00\",\"index\":\"\",\"fulltext\":\"\"},{\"type\":\"submitted\",\"content\":\"Plant and Soil\",\"date\":\"2022-07-02T18:07:08+00:00\",\"index\":\"\",\"fulltext\":\"\"}],\"status\":\"published\",\"journal\":{\"display\":true,\"email\":\"info@researchsquare.com\",\"identity\":\"plant-and-soil\",\"isNatureJournal\":false,\"hasQc\":true,\"allowDirectSubmit\":false,\"externalIdentity\":\"plso\",\"sideBox\":\"Learn more about [Plant and Soil](https://www.springer.com/journal/11104)\",\"snPcode\":\"11104\",\"submissionUrl\":\"https://submission.nature.com/new-submission/11104/3\",\"title\":\"Plant and Soil\",\"twitterHandle\":\"\",\"acdcEnabled\":true,\"dfaEnabled\":true,\"editorialSystem\":\"em\",\"reportingPortfolio\":\"Springer Hybrid\",\"inReviewEnabled\":true,\"inReviewRevisionsEnabled\":false}}],\"origin\":\"\",\"ownerIdentity\":\"9fd36c25-a587-4fb9-94fd-9e2c5f18fe04\",\"owner\":[],\"postedDate\":\"July 19th, 2022\",\"published\":true,\"recentEditorialEvents\":[],\"rejectedJournal\":[],\"revision\":\"\",\"amendment\":\"\",\"status\":\"in-revision\",\"subjectAreas\":[],\"tags\":[],\"updatedAt\":\"2022-08-25T20:04:13+00:00\",\"versionOfRecord\":[],\"versionCreatedAt\":\"2022-07-19 18:44:34\",\"video\":\"\",\"vorDoi\":\"\",\"vorDoiUrl\":\"\",\"workflowStages\":[]},\"version\":\"v1\",\"identity\":\"rs-1798187\",\"journalConfig\":\"researchsquare\"},\"__N_SSP\":true},\"page\":\"/article/[identity]/[[...version]]\",\"query\":{\"redirect\":\"/article/rs-1798187\",\"identity\":\"rs-1798187\",\"version\":[\"v1\"]},\"buildId\":\"wLkW0s4AflPzk-lpfg-fK\",\"isFallback\":false,\"isExperimentalCompile\":false,\"dynamicIds\":[84888],\"gssp\":true,\"scriptLoader\":[]}","source_license":"CC-BY-4.0","license_restricted":false}