Biochar-Based Integrated Nutrient Management Improves Soil Quality and Biological Functioning in a Rice–Wheat Cropping System

Biochar-Based Integrated Nutrient Management Improves Soil Quality and Biological Functioning in a Rice–Wheat Cropping System | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Biochar-Based Integrated Nutrient Management Improves Soil Quality and Biological Functioning in a Rice–Wheat Cropping System Anita Jaswal, Chandra Mohan Mehta, Arshdeep Singh, Arun Kumar, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8557311/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 10 You are reading this latest preprint version Abstract The key limitation to crop productivity in Punjab is nutrient imbalance and declining soil fertility, with intensive rice–wheat cropping systems and the removal of above-ground biomass after harvest negatively affecting soil health. Although mineral fertilizers have played a crucial role in achieving food self-sufficiency, maintaining long-term productivity requires sustaining adequate levels of soil organic matter to support physical, chemical, and biological soil processes. In this context, the application of amendments derived from agricultural biomass, such as biochar, can be considered a viable option for enhancing soil fertility and sustainability. The objective of the present study was to evaluate the impact of rice straw biochar combined with organic and inorganic fertilizers on the physico-chemical and biological properties of soil under a rice–wheat cropping system. The field experiment was conducted at the Department of Agronomy, Crop Research Centre, Lovely Professional University, Phagwara, using a randomized block design with nine treatments and three replications. Rice straw biochar was applied at recommended rates alongside fertilizers and organic amendments. The results indicated that biochar-amended plots exhibited higher soil pH, porosity, bulk density, nutrient availability, soil enzymatic activities, and organic carbon content than the control and sole RDF treatments. Biochar application reduced soil bulk density, increased organic carbon content, regulated soil pH, and enhanced enzymatic activity, indicating improved soil biological functioning. The integration of rice straw biochar with organic and inorganic nutrient sources—particularly 50% RDF combined with poultry manure or farmyard manure and biochar—has emerged as a promising, farmer-viable approach for improving soil quality and achieving sustainable productivity in the rice–wheat cropping system. The significance of the proposed study is placed in the context of sustainable development, as it aims to meet SDG-2 (Zero Hunger) by enhancing soil fertility and crop yields, SDG-12 (Responsible Consumption and Production) by recycling rice straw into biochar, SDG-13 (Climate Action) by improving the efficiency of soil carbon sequestration, and finally SDG-15 (Life on Land) by improving the health of the soil. The proposed biochar-based approach offers a sustainable alternative to fertilizer-intensive practices prevalent in the Indo-Gangetic Plains. Sustainable agriculture enzymatic activities soil fertility amendment biochar Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 1. Introduction One of the most useful and strategically significant agroecosystems in South Asia is the rice-wheat system of the Indo-Gangetic Plains (IGP), which provides food security for hundreds of millions of people. High-yielding varieties, irrigation, and intensive use of mineral fertilizers have been the foundation of this system since the Green Revolution, maintaining the same level of production (Lal, 2016; Zhang et al., 2021). Although remarkable gains in yields have been achieved through these practices, continuous cultivation over extended periods, limited crop diversification, and the systematic eradication or burning of crop remnants have increasingly altered the physical organization of soils, nutrient cycling, and biological processes. The reduction in soil organic carbon (SOC) stocks has become a major concern, as SOC supports aggregation, water retention, nutrient buffering, and microbial habitat stability (Naeem et al., 2018; Bashir et al., 2021). Carbon and water loss are common, and structural degradation, decreased porosity, compaction, and a lower cation-exchange potential that limit root growth and nutrient uptake contribute to SOC loss. Moreover, organic matter degradation reduces soil resilience to temperature and variable precipitation, thereby increasing the degree of unpredictability under climate variability (Brempong et al., 2023). Although mineral fertilizers will always be necessary to meet crop nutrient demands, prolonged exclusive use of them contributes to nutrient imbalances, low nutrient-use efficiency, soil acidification or alkalization, and inhibition of beneficial microflora (Gul et al., 2015; Das et al., 2017). As a result, the restriction in soil fertility of intensive rice-wheat systems is increasingly linked not only to nutrient deficiencies but also to impaired soil functioning, specifically to interference with carbon-mediated nutrient-cycling mechanisms (Lal, 2016). The combination of organic and inorganic inputs, which constitute integrated nutrient management strategies, has consequently become a subject of renewed interest as a means of replenishing soil quality while remaining productive. Organic amendments provide labile carbon fractions that promote microbial activity and aggregation, including farmyard manure, Vermicompost, and poultry manure. However, these materials are readily degraded under subtropical climate conditions, resulting in temporary advantages and insufficient long-term carbon stabilization (He et al., 2017). It is then inferred that the required carbon inputs must be not only biologically interactive but also structurally persistent. This has been one of the promising candidates, the biochar. Biological material is converted to biomass via pyrolysis, which is conducted under low oxygen conditions. It is characterized by the presence of aromatic carbon, a high surface area, an uneven charge distribution, and high density (Kamau et al., 2019; Singh et al., 2022). Such physicochemical properties can be used to modify soil processes in various ways. First, it is porous, which enhances soil water retention and aeration. Second, the surface functional groups enhance cation-exchange capacity, thereby increasing nutrient retention and reducing leaching losses. Third, biochar-derived carbon is relatively recalcitrant, resulting in long-term stabilization of SOC and potential carbon sequestration (He et al., 2017). Biochar also interacts with soil biological systems, in addition to its physical and chemical effects. It may act as a protective microhabitat for microorganisms, regulate pH, and influence enzyme-mediated nutrient changes (Juriga et al., 2018). It has been reported that microbial biomass and enzyme activity increase with biochar application, particularly with nutrient inputs (Lusiba et al., 2017). However, the agronomic response of biochar is unpredictable because it is typically low in readily available nutrients. That is why it appears to be particularly promising when combined with mineral fertilizers and organic manures (Oladele et al., 2019; Yadav et al., 2018). Biochar could synergize with reduced doses of mineral fertilizers and organic additives (Hu et al., 2024). Although mineral fertilizers are abundant in readily available nutrients, organic manure contains labile carbon that enhances microbial activity, and biochar contains a stable carbon skeleton that enhances nutrient retention and habitat formation (Rahman et al., 2019). Such interactions are able to increase nutrient recovery, phosphorus through adsorption and desorption, and potassium retention, with the net effect being the optimisation of the nutrient cycling in the soil system. Additionally, SOC and aggregation may be improved to mitigate the trend toward increased bulk density, which frequently accompanies intensive cropping (Du et al., 2017). Despite an emerging literature body on biochar worldwide, very few field-based studies have been carried out on long-term rotation of rice-wheat in Punjab. A large share of the existing literature focuses on short-term laboratory results or on evaluating impacts within a single season, and this may be insufficient to test the potential cumulative effects on soil carbon interactions and enzyme activities. In particular, the impact of biochar-based nutrient management on relevant soil enzyme indicators (urease, dehydrogenase, acid phosphatase, and alkaline phosphatase) under subtropical field conditions remains poorly studied. These enzymes are directly associated with the mineralization of nitrogen, respiration, and cycling of phosphorus by microorganisms; therefore, they are considered as helpful indicators of soil biosphere and phosphorus transformation efficacy (Jian et al., 2016). A better method for assessing soil functional recovery is to examine enzyme activity and physicochemical parameters (Xie et al., 2017). Changes in bulk density, porosity, pH, and nutrient availability should be analyzed in conjunction with biological indicators to determine whether the implementation of integrated nutrient management methods is likely to increase overall soil resilience without increasing nutrient availability. Furthermore, with increasing attention to mitigating climate change and sustainable intensification, the agronomic and environmental significance of biochar-based systems for carbon stabilization and nutrient-use efficiency warrants consideration (Lal, 2016; Brempong et al., 2023). Therefore, the present study was conducted to assess the effects of biochar produced from rice straw, along with organic and inorganic nutrient sources, on the physicochemical characteristics of soils, nutrient status, and biological indicators in a rice-wheat growing system in Punjab. It was hypothesized that complete replacement of mineral fertilizers with organic manures in the existence of biochar would (i) raise the accumulation of SOC and structural stability, (ii) raise nutrient retention and availability, (iii) boost soil enzymatic activity as indicative of improved biological functioning and (iv) boost a more sustainable and climate-resilient nutrient management system in intensive cereal system. Relevance to Sustainable Development Rice-wheat cropping systems in South Asia face the double burden of deteriorating soil quality and environmentally unsustainable residue management practices. The use of excess rice straw as biochar is a nature-based solution that can mitigate open-field burning, improve nutrient-use efficiency, and sequester soil organic carbon. These approaches directly address the global SDGs 2.4 (sustainable food production systems), 12.5 (substantial reduction of waste through recycling), and 13.2 (climate change mitigation actions). Thus, the assessment of biochar in the context of integrated nutrient management is not only an agronomic issue but also an imperative of sustainability. 2. Materials and methods 2.1 Experiment Location and Conditions : The field study was conducted for two consecutive years (July 2018-April 2020) at the Crop Research Centre of the Department of Agronomy, Lovely Professional University, Phagwara, Punjab, India. The experimental farm is situated in the Trans-Gangetic Plains at approximately 31°24′ N latitude and 75°69′ E longitude, with an average elevation of approximately 245 m amsl. A semi-arid subtropical climate and a distinct monsoon season characterize the area. The average maximum summer temperatures often touch about 42°C, whereas winter minimum temperatures sometimes drop to as low as 6°C. The average annual rainfall in the region is approximately 800 mm, with the majority occurring from July to September during the southwest monsoons. Isolated rainfall also occurs from December to April due to western disturbances. In the experimental time, the total rainfall was 199.8 mm, and seasonal temperatures ranged from 5°C to 21°C. The farm has been managed following integrated farming systems since 2010. The soil type- Typic Haplustept with a sandy loam texture, moderate drainage, and low to medium fertility. Before the experiment was implemented, the land had been used for several years in a conventional rice-wheat crop rotation, which is prevalent in central Punjab. 2.2 Plant material and source - The plant materials used in the study included rice ( Oryza sativa L., cv. Pusa Basmati 1121) and wheat ( Triticum aestivum L., cv. PBW 550). Certified seeds of both crops were procured from authorized agricultural sources recommended by the Punjab Agricultural University (PAU), Ludhiana. The crops were cultivated under field conditions at the Agronomy Research Farm, Lovely Professional University, Phagwara, Punjab, India (31°24′ N latitude, 75°69′ E longitude). No wild plant material was collected for this study. 2.3 Experimental details : The field investigation was conducted for two consecutive cropping cycles, encompassing the Kharif and Rabi seasons of 2018–19 and 2019–20. The study evaluated nine nutrient management treatments to assess the individual and combined effects of mineral fertilizer, biochar, and organic amendments. The treatments included: (i) an unfertilized control, (ii) 100% recommended dose of fertilizer (RDF), and (iii–viii) combinations of 50% RDF integrated with biochar and varying proportions (25% or 50%) of farmyard manure (FYM), vermicompost (VC), or poultry manure (PM). For the rice crop, the recommended fertilizer dose (RDF) was 42:30:30 kg ha⁻¹ of N: P₂O₅: K₂O. Organic amendments were applied at the following rates: FYM at 12.5 t ha⁻¹, vermicompost at 1 t ha⁻¹, poultry manure at 2 t ha⁻¹, and rice straw–derived biochar at 10 t ha⁻¹. For the succeeding wheat crop, RDF was applied at 120:60:60 kg ha⁻¹ of N: P₂O₅:K₂O, with FYM (10 t ha⁻¹), vermicompost (2.5 t ha⁻¹), and poultry manure (6 t ha⁻¹) adjusted according to crop requirement recommendations of Punjab Agricultural University (PAU), Ludhiana. All organic inputs were incorporated on a dry-weight basis during final land preparation to ensure uniform mixing within the soil. Mineral fertilizers were supplied through urea (N source), single superphosphate and diammonium phosphate (P sources), and muriate of potash (K source). Phosphorus and potassium were applied entirely as basal doses, whereas nitrogen was split, with half applied at sowing/transplanting and the remainder at critical crop growth stages. The biochar used in the experiment was produced from rice straw via pyrolysis. It exhibited an alkaline reaction (pH 8.94) and low electrical conductivity (0.07 dS m⁻¹). The material contained 396 g kg⁻¹ total carbon, 4.08 g kg⁻¹ total nitrogen, 738 mg kg⁻¹ total phosphorus, and 8.35 g kg⁻¹ total potassium. Physical properties included a bulk density of 0.117 g cm⁻³, particle density of 0.273 g cm⁻³, total porosity of 60.07%, solid space of 39.9%, and ash content of 37.6%. Microstructural characteristics of the biochar were examined using electron microscopy at the Central Instrumentation Facility, Lovely Professional University (Fig. 3 ). 2.4 Crop management : The experiment was conducted on the growth of rice in the kharif season and wheat in the rabi season as per the recommended agronomic practices of Punjab Agricultural University. For rice, nursery beds were raised 30 days prior to transplanting, and 25-day-old seedlings of the cv. Pusa Basmati 1121 was transplanted in puddled fields at a spacing of 20 × 15 cm. Puddling was performed with a tractor-operated rotavator in standing water to form a homogeneous muddy layer favorable for seedling establishment. Wheat variety PBW-550 was planted after harvesting the rice crop by manual seed drill at a depth of 3–5 cm with a row spacing of 22 cm and plant spacing of 5–7 cm. The wheat seed rate was maintained at 120 kg ha⁻¹. Intercultural operations, including irrigation, weed management, and plant protection, were performed equally across all treatments in accordance with the regional package of practices. Rice was harvested by hand with sickles in November, when the grains had attained physiological maturity and a moisture content of approximately 25%. Threshing was done after sun drying to 12–14% moisture content. Wheat harvesting occurred in late April when the crop turned golden yellow, and threshing was done plot-wise by beating the crop bundles on a drum. All crop residues, except those used for biochar production, were removed from the plots to ensure uniformity. 2.5 Soil physico-chemical Analysis : Before sowing and after harvest at the end of every season, composite soil samples (015 cm deep) were collected. The samples were air-dried, sieved (2 mm), and analyzed using standard procedures for physicochemical property determination. The pH and electrical conductivity were measured in a soil-water suspension. The Walkley-Black wet oxidation procedure was used to determine soil organic carbon. Nitrogen, phosphorus, and potassium were determined by standard alkaline KMnO4 distillation (Subbiah & Asija,1956), Olsen extraction (Olsen et al., 1956; Jackson, 1991), and flame photometry (Blake & Hartage, 1986 ), respectively, in accordance with standard soil analysis protocols. The core method was used to measure bulk density, and the values of bulk and particle density were used to calculate porosity 2.6 Soil enzymes assay : Dehydrogenase activity was estimated using the triphenyl tetrazolium chloride (TTC) reduction method, and results were expressed as µg TPF g⁻¹ soil day⁻¹ ( Tatabati, 1982 ). Urease activity was determined by measuring ammonium release following urea hydrolysis (McGarity & Myers, 1967 ). Acid and alkaline phosphatase activities were measured using p-nitrophenyl phosphate as the substrate under appropriate buffered conditions (Tata & Bremner, 1969). Enzyme activities were expressed on a dry-soil basis, following standard procedures reported in the soil enzymology literature. 2.7 Statistical analysis : The data were analyzed using analysis of variance (ANOVA) with SPSS version 20.0 statistical software program (SPSS Inc.). The means were then compared using Duncan's multiple-range test. The results were reported as the mean ± standard deviation, with significance at p ≤ 0.05. 3. Results 3.1 Impact of Biochar combined fertilizers on soil physico-chemical properties : Treatment did not have a significant effect on bulk density or porosity in each of the two years of experimentation (p > 0.05); nevertheless, some consistent numerical patterns were noticeable. Biochar-amended plots tended to have less bulk density than control and sole RDF in both years after the rice harvest (Table 1 ). Following the initial crop season, bulk density was found to be 1.74–1.85 g cm − 1 , and the values in the conditions of integrated biochar were relatively lower. In the second year, the changes were more moderate, indicating that structures became gradually more stable rather than changing suddenly due to changes in soil compaction. The control plots showed similar bulk density across seasons, suggesting little structural enhancement with mineral fertilizer alone. This was likewise witnessed with the bulk density of 1.791.87 g cm -1 (202021) and 1.751.85 g cm -1 (202122) in wheat cultivation. Although the difference was not statistically significant, a steady decrease with biochar-based treatment suggests increased aggregation and greater pore connectivity, likely due to the porous structure and low particle density of biochar. There was no significant difference in the porosity between treatments; nevertheless, biochar-integrated plots displayed a consistently small (but significantly higher porosity than control and 100 percent RDF treatments. These quantitative gains suggest slow changes in soil physical properties, possibly due to increased aggregation and reduced compaction effects under integrated nutrient management. Table 1 Effect of biochar -based amendments on soil physical properties (mean ± S.E) over Two Years in a rice–wheat cropping system. 2018–2019 (Rice) 2018–2019 (Wheat) 2019–2020 (Rice) 2019–2020 (Wheat) Treatments Bulk density (g/cm³) Porosity (%) Bulk density (g/cm³) Porosity (%) Bulk density (g/cm³) Porosity% Bulk density (g/cm³) Porosity% T 0 -Control (no fertilizer) 1.83 ± 0.06a 24.77 ± 4.83a 1.87 ± 0.12a 26.87 ± 8.46a 1.82 ± 0.09a 25.10 ± 10.54a 1.85 ± 0.18a 29.1 ± 7.87a T 1 -100%RDF 1.85 ± 0.06a 25.4 ± 7.37a 1.84 ± 0.15a 27.50 ± 5.68a 1.86 ± 0.08a 25.6 ± 9.17a 1.83 ± 0.15a 30.53 ± 6.63a T 2 - 50%RDF + Biochar 1.82 ± 0.10a 26.67 ± 7.4a 1.82 ± 0.15a 28.9 ± 8.37a 1.80 ± 0.13a 27.23 ± 3.96a 1.80 ± 0.18a 31.3 ± 7.06a T 3 -50%RDF + 25%FYM+Biochar 1.80 ± 0.14a 27.23 ± 8.7a 1.83 ± 0.22a 30.03 ± 12.11a 1.77 ± 0.10a 29.3 ± 4.98a 1.79 ± 0.14a 32.2 ± 10.3a T 4 -50%RDF + 50%FYM+Biochar 1.78 ± 0.13a 29.7 ± 6.86a 1.79 ± 0.17a 34.70 ± 12.16a 1.75 ± 0.17a 31.10 ± 8.81a 1.75 ± 0.16a 35.6 ± 10.9a T 5 -50%RDF + 25%Vermi-compost + Biochar 1.79 ± 0.09a 29.93 ± 7.54a 1.82 ± 0.11a 31.57 ± 10.11a 1.77 ± 0.09a 28.00 ± 8.25a 1.80 ± 0.18a 33.8 ± 10.53a T 6 -50%RDF + 50%Vermi compost+ Biochar 1.76 ± 0.12a 29.07 ± 9.25a 1.81 ± 0.06a 33.53 ± 8.33a 1.74 ± 0.21a 31.67 ± 12.45a 1.77 ± 0.22a 34.6 ± 6.85a T 7 -50%RDF + 25%Poultry manure+ Biochar 1.78 ± 0.15a 29.83 ± 7.14a 1.79 ± 0.13a 32.94 ± 6.73a 1.73 ± 0.20a 30.50 ± 6.6a 1.78 ± 0.24a 33.03 ± 4.19a T 8 -50%RDF + 50%Poultry manure+ Biochar 1.74 ± 0.12a 30.03 ± 8.44a 1.82 ± 0.13a 33.53 ± 4.78a 1.70 ± 0.26a 33.53 ± 9.51a 1.77 ± 0.13a 34.65 ± 5.91a *The figures represented are the average of three replications. ± S.E is the standard error of the mean. Means that differ substantially among treatments are denoted by various letters in superscripts. Note- RDF- Recommended dose of fertilizer, FYM- farm yard manure, There was relative stability in soil pH across treatments and seasons, indicating that the soil's buffering capacity was high, given its sandy loam texture. However, biochar treatments exhibited higher pH values. The highest pH (7.10) was measured in 50 percent RDF + 50 percent poultry manure + biochar, whereas the lowest pH (6.93) was in the control and in RDF alone (Table 2 ). The same pattern persisted during the wheat season, with 50% RDF + 50% FYM + biochar yielding slightly higher pH values (7.12, 7.14). These marginal improvements can be explained by the fact that rice straw biochar is alkaline and contains ash that can neutralize soil acidity and increase base saturation. However, the small magnitude of change indicates that biochar had little to no effect on soil pH, beyond stabilizing it. Table 2 Effect of biochar -based amendments on soil chemical properties (mean ± S.E) over Two Years in a rice–wheat cropping system. 2018–2019 (Rice) 2018–2019 (Wheat) 2019–2020 (Rice) 2019–2020 (Wheat) Treatments pH EC dSm − 1 pH ECdSm − 1 pH EC dSm − 1 pH EC dSm − 1 T 0 -Control (no fertilizer) 6.93 ± 0.07a 0.216 ± 0.013a 6.94 ± 0.11a 0.218 ± 0.023a 6.94 ± 0.11a 0.217 ± 0.007a 6.95 ± 0.25a 0.219 ± 0.021ab T 1 -100%RDF 6.96 ± 0.10a 0.217 ± 0.013a 6.97 ± 0.26a 0.220 ± 0.009a 6.97 ± 0.10a 0.219 ± 0.014a 6.98 ± 0.19a 0.222 ± 0.010ab T 2 - 50%RDF + Biochar 6.98 ± 0.10a 0.219 ± 0.014a 7.00 ± 0.27a 0.222 ± 0.008a 7.00 ± 0.08a 0.221 ± 0.007a 7.01 ± 0.29a 0.224 ± 0.011ab T 3 -50%RDF + 25%FYM+Biochar 7.03 ± 0.14a 0.221 ± 0.013a 7.02 ± 0.14a 0.223 ± 0.016a 7.02 ± 0.14a 0.223 ± 0.014a 7.06 ± 0.16a 0.226 ± 0.013a T 4 -50%RDF + 50%FYM+Biochar 7.05 ± 0.17a 0.223 ± 0.009a 7.12 ± 0.09a 0.230 ± 0.008a 7.06 ± 0.17a 0.225 ± 0.016a 7.14 ± 0.16a 0.233 ± 0.010a T 5 -50%RDF + 25%Vermi-compost + Biochar 7.02 ± 0.07a 0.219 ± 0.009a 7.04 ± 0.13a 0.226 ± 0.009a 7.04 ± 0.08a 0.220 ± 0.010a 7.08 ± 0.21a 0.229 ± 0.013a T 6 -50%RDF + 50%Vermi compost+ Biochar 7.04 ± 0.13a 0.221 ± 0.014a 7.08 ± 0.09a 0.228 ± 0.013a 7.06 ± 0.15a 0.223 ± 0.017a 7.11 ± 0.17a 0.231 ± 0.010a T 7 -50%RDF + 25%poultry manure+ Biochar 7.07 ± 0.18a 0.222 ± 0.011a 7.05 ± 0.15a 0.223 ± 0.010a 7.09 ± 0.15a 0.224 ± 0.013a 7.07 ± 0.15a 0.227 ± 0.06a T 8 -50%RDF + 50%poultry manure+ Biochar 7.10 ± 0.17a 0.226 ± 0.018a 7.10 ± 0.11a 0.225 ± 0.017a 7.12 ± 0.17a 0.228 ± 0.018a 7.12 ± 0.34a 0.228 ± 0.017a *The figures represented are the average of three replications. ± S.E is the standard error of the mean. Different superscripts denote the means that differ substantially among treatments. Note- RDF- Recommended dose of fertilizer, FYM- farm yard manure, Electrical conductivity (EC) differed substantially among treatments within the 2021 rice season. The EC increased with biochar under organic manures, particularly with 50% RDF + 50% poultry manure + biochar (0.226 dS m − 1 ), and was statistically similar to the FYM-integrated treatment (0.223 dS m − 1 ). The lowest EC values were observed in the control and sole RDF treatments. This trend was repeated in further wheat seasons when biochar-manure combinations always displayed a relatively higher value of EC. The EC increase was likely due to improved nutrient retention and availability, as the values were within the safe agronomic range. Taken together, these findings suggest that the integration of biochar had a modest but positive effect on soil structural and chemical buffering, but did not cause significant adverse effects on salinity. 3.2 Impact of Biochar combined fertilizers on soil nutrient status : There was a substantial increase in soil nutrient availability under biochar-based nutrient management (p < 0.05). After rice harvest, the greatest amount of nitrogen was found at less than 50% RDF + 50% poultry manure + biochar (562.6 and 560.5 kg ha − 1 in a two-year-old cultivated field), and the least amount at the control (276.0 and 281.3 kg ha − 1 ) (Tables 3 and 4 ). The scope of growth indicates improved nitrogen storage and mineralization under mixed treatment conditions with organic and biochar. The porous nature of biochar could have minimized nitrogen loss via leaching or volatilization and, at the same time, enhanced mineralization by microorganisms. Maximum available nitrogen moved slightly toward the 50% RDF + 50% FYM + biochar treatment (563.8 and 566.3 kg ha − 1 ) during the wheat season, after which the vermicompost-integrated treatments ranked second. This seasonal change is likely related to variations in decomposition rates and nutrient release patterns from organic inputs, and FYM provides a more long-term nitrogen supply due to cooler wheat-growing conditions. Table 3 Effect of biochar-based amendments on soil nutrient status (mean ± S.E) of rice crop during both years 2018–2019 (Rice) 2019–2020 (Rice) Treatments Available N kg ha-1 Available P kgha − 1 Available K kgha − 1 OC (%) Available N kg ha-1 Available P kgha − 1 Available K kgha − 1 OC (%) T 0 -Control (no fertilizer) 276.00 ± 1.63g 6.39 ± 0.06g 244.77 ± 2.68g 0.58 ± 0.02i 281.37 ± 1.29h 6.65 ± 0.17g 240.23 ± 0.86h 0.59 ± 0.02g T 1 -100%RDF 461.23 ± 0.86f 13.87 ± 0.25h 309.00 ± 0.82f 0.64 ± 0.02h 466.43 ± 1.14g 14.84 ± 0.26f 305.67 ± 1.23g 0.66 ± 0.01f T 2 - 50%RDF + Biochar 482.28 ± 0.88e 17.20 ± 0.29f 314.33 ± 0.98e 0.71 ± 0.01g 480.23 ± 0.71f 20.36 ± 0.18e 311.93 ± 1.27f 0.76 ± 0.01e T 3 -50%RDF + 25%FYM+Biochar 518.00 ± 1.63d 19.40 ± 0.37e 337.03 ± 0.74d 0.87 ± 0.01f 522.77 ± 1.93d 20.52 ± 0.14e 335.00 ± 1.36e 0.89 ± 0.02d T 4 -50%RDF + 50%FYM+Biochar 551.97 ± 1.59b 21.77 ± 0.21c 345.90 ± 1.28c 1.01 ± 0.01c 552.77 ± 1.11b 22.67 ± 0.07d 344.30 ± 0.70c 1.04 ± 0.02b T 5 -50%RDF + 25%Vermi-compost + Biochar 519.97 ± 1.49c 20.17 ± 0.29d 335.00 ± 1.31d 0.91 ± 0.01e 520.17 ± 0.87e 20.63 ± 0.04c 333.43 ± 0.76e 0.95 ± 0.02c T 6 -50%RDF + 50%Vermi compost+ Biochar 548.53 ± 1.70c 21.53 ± 0.25c 343.73 ± 1.32c 0.96 ± 0.01d 544.83 ± 2.37d 21.63 ± 0.10d 340.57 ± 0.82d 0.97 ± 0.02c T 7 -50%RDF + 25%poultry manure+ Biochar 553.37 ± 0.95b 24.03 ± 0.40b 354.20 ± 1.66b 1.06 ± 0.01b 556.17 ± 1.55b 23.87 ± 0.21b 350.13 ± 1.17b 1.05 ± 0.01b T 8 -50%RDF + 50%poultry manure+ Biochar 562.60 ± 1.28a 24.93 ± 0.69a 365.07 ± 0.74a 1.20 ± 0.01a 560.53 ± 1.11a 25.13 ± 0.05a 360.70 ± 1.16a 1.16 ± 0.03a *The figures represented are the average of three replications. ± S.E is the standard error of the mean. Different superscripts denote the means that differ substantially among treatments. Note- RDF- Recommended dose of fertilizer, FYM- farm yard manure, Table 4 Effect of biochar-based amendments on soil nutrient status (mean ± S.E) of wheat crop during both years 2018–2019 Wheat 2019–2020 Wheat Treatments Available N kg ha-1 Available P kgha − 1 Available K kgha − 1 OC (%) Available N kgha − 1 Available P kgha − 1 Available K kgha − 1 OC (%) T 0 -Control (no fertilizer) 284.7 ± 1.93h 7.15 ± 0.03h 238.33 ± 0.68i 0.60 ± 0.02h 290.67 ± 1.25g 7.64 ± 0.24h 240.40 ± 1.18i 0.62 ± 0.02i T 1 -100%RDF 475.3 ± 1.25g 21.17 ± 0.29g 312.90 ± 0.99h 0.79 ± 0.02g 477.67 ± 2.05f 22.55 ± 0.10g 316.37 ± 1.68h 0.82 ± 0.02h T 2 - 50%RDF + Biochar 493.60 ± 1.10f 22.23 ± 0.25f 339.43 ± 0.70g 0.94 ± 0.01f 496.00 ± 1.63e 23.56 ± 0.28f 338.73 ± 1.03g 0.96 ± 0.02g T 3 -50%RDF + 25%FYM+Biochar 523.80 ± 1.07e 25.57 ± 0.21c 368.20 ± 0.82d 1.17 ± 0.02d 525.00 ± 2.16d 26.34 ± 0.15c 370.77 ± 1.29d 1.22 ± 0.02d T 4 -50%RDF + 50%FYM+Biochar 563.80 ± 1.19a 27.23 ± 0.29a 386.23 ± 0.82a 1.45 ± 0.02a 566.33 ± 1.25a 28.52 ± 0.32a 387.80 ± 1.36a 1.52 ± 0.02a T 5 -50%RDF + 25%Vermi-compost + Biochar 544.37 ± 0.70d 24.77 ± 0.37d 363.37 ± 0.98e 1.12 ± 0.01e 548.0 ± 1.63c 25.48 ± 0.27d 365.27 ± 1.72e 1.17 ± 0.01e T 6 -50%RDF + 50%Vermi compost+ Biochar 562.57 ± 1.27ab 26.67 ± 0.34b 377.90 ± 1.20b 1.32 ± 0.01b 564.67 ± 1.25a 27.60 ± 0.18b 380.37 ± 1.52b 1.38 ± 0.01b T 7 -50%RDF + 25%poultry manure+ Biochar 557.80 ± 0.49c 24.03 ± 0.17e 356.13 ± 0.82f 1.10 ± 0.01e 560.67 ± 1.25b 24.61 ± 0.19e 360.17 ± 1.42f 1.14 ± 0.02f T 8 -50%RDF + 50%poultry manure+ Biochar 560.40 ± 0.59a 26.03 ± 0.12c 371.40 ± 1.07c 1.26 ± 0.01c 563.00 ± 0.82ab 26.69 ± 0.21c 374.23 ± 1.59c 1.33 ± 0.01c *The figures represented are the average of three replications. ± S.E is the standard error of the mean. Different superscripts denote the means that differ substantially among treatments. Note- RDF- Recommended dose of fertilizer, FYM- farm yard manure, Biochar-enhanced treatments also increased available phosphorus. Fifty percent RDF and fifty percent poultry manure and biochar showed the maximum availability of phosphorus (24.93 and 25.13 kg ha − 1 ), whereas control plots showed a significantly lower concentration (6.39 and 6.65 kg ha − 1 ). The same trends were recorded in wheat, where the availability of phosphorus grew even more, under integrated treatments (to 28.52 kg ha − 1 ). This increased level may be due to low phosphorus fixation, increased microbial activity, and accelerated desorption from biochar surfaces. The availability of potassium had a similar trend. In rice production, 50% RDF + 50% poultry manure + biochar recorded the highest K values (365.0 and 360.7 kg ha-1), whereas the control consistently had the lowest values. The highest potassium content was recorded after wheat harvest (50% RDF + 50% FYM + biochar; 386.23 and 387.0 kg ha-1). The rise in K supply is likely due to both direct nutrient addition via manure and uptake in biochar-amended soils. There was a significant response of soil organic carbon (SOC) to integrated treatments. SOC varied across treatments and seasons, ranging from 0.39% to 1.52%. The maximum SOC values after rice were found to be under 50 percent RDF + 50 percent poultry manure + biochar (1.20 percent and 1.16 percent), but less than 0.60 percent was observed in control plots. Following wheat harvesting, SOC increased, particularly when 50% RDF + 50% FYM + biochar was applied (1.45% and 1.52%). These increases are due to the direct addition of carbon from biochar and organic manure, as well as reduced carbon mineralization losses. The increase in the cumulative SOC across seasons suggests improved carbon stabilization and soil quality under integrated nutrient management. Generally, biochar with organic amendments and low mineral fertilizer consistently enhanced soil nutrient status and carbon content compared with single fertilizers. The synergistic interactions among nitrogen, phosphorus, potassium, and SOC indicated increased nutrient cycling efficiency and greater soil functional resilience in the rice-wheat system. 3.3 Impact of Biochar-based amendments on soil biological indicators: Soil urease activity The activity of soil urease was evidently stratified with depth, and in all cases, the activity in the surface layer (015 cm) was much higher than that in the subsurface (15 30 cm) in both cropping seasons (Fig. 4 a, b). This trend indicates greater accumulation of organic residue and microbial biomass in surface soil. Urease activity was significantly higher with integrated biochar treatments than with the control and individual RDF treatments. The maximum urease activity was observed with < 50% RDF + 50% poultry manure + biochar, yielding 9.46 and 5.83mg urea g − 1 soil 24 h − 1 in surface and subsurface soils, respectively. Such values were statistically equivalent to the 50 percent RDF + 25 percent poultry manure + biochar treatment. Vermicompost-incorporated treatments also exhibited high urease activity, whereas control plots consistently had the lowest activity. The significant improvement in poultry manure-biochar mixture implicates synergistic impacts of labile organic nitrogen sources as well as porous biochar matrix, which could enhance the colonization of microbes and the effectiveness of mineralization of nitrogen. The development of urease activity did not differ significantly among treatments in the wheat season, with the highest activity at 50% RDF + 50% FYM + biochar (8.65 and 6.73mg urea g − 1 soil 24 h − 1 in surface and subsurface soils). This seasonal change is likely due to slower decomposition of FYM during the colder wheat-growing period, resulting in prolonged nitrogen release. All treatments containing biochar showed a significant improvement over the control across seasons, demonstrating the potential to enhance nitrogen transformation through integrated nutrient management. Soil dehydrogenase activity The global microbial oxidative activity indicator (dehydrogenase activity (DHA)) was very responsive to integrating nutrients using biochar (Fig. 4 c, d). The highest DHA was observed at 50 percent RDF + 50 percent poultry manure + biochar (14.2 and 10.47 mg TPF g − 1 soil day − 1 for surface and subsurface, respectively), and then decreased with poultry manure treatments. Control plots showed significantly low values, indicating that microbial respiration was suppressed under sole mineral fertilization. During the following wheat season, DHA improved significantly, particularly when the percentage of RDF + 50% FYM + biochar was less than 50%, with surface soil activity reaching 27.5 mg TPF g − 1 soil on day 1. The pronounced accumulation of the increase in wheat indicates cumulative effects of carbon addition and microbial stabilization across crop-planting times. Surface soils consistently had higher DHA than subsurface soils, further supporting the contribution of organic inputs to enhanced microbial metabolism. The stable increase in DHA at biochar manure mixtures suggests the existence of better conditions of microbial habitats, presumably through enhanced SOC, enhanced aeration, and enhanced moisture retention. The findings indicate that biochar can stabilize carbon and promote the active role of microbes in the presence of nutrients. Soil acid phosphatase activity There was significant variation in acid phosphatase activity among treatments, and it was consistently higher in surface soils (Fig. 5 a, b). The activity varied across the rice crop, with the highest value of 50% RDF + 50% poultry manure + biochar (197.33 and 75.27 µgPNPg − 1 soil h − 1 in the surface and subsurface, respectively) observed. Control plots showed the least activity, indicating low phosphorus cycling in the biological component when fertilizer was used alone. During the wheat season, the highest activity of acid phosphatase appeared in RDF + 50% FYM + biochar (152.3 and 72.4 µgPNPg − 1 soil h − 1 ). The observed increases indicate improved phosphorus mineralization with integrated nutrient management. High phosphatase activity may indicate increased phosphorus demand by microorganisms and enhanced substrate availability in biochar-amended soils. The significant improvement in phosphatase activity during biochar-organic manure treatments indicates increased biological phosphorus turnover and possibly decreased reliance on external P inputs. Soil alkaline phosphatase activity The trends in alkaline phosphatase were unsurprising and resembled those of acid phosphatase, except that alkaline phosphatase activity was higher in the topsoils and in biochar-integrated treatments (Fig. 5 c, d). The highest activity was observed in 50 percent RDF + 50 percent poultry manure + biochar (181.33 and 74.56 µgPNPg − 1 soil h − 1 ) during rice, whereas control plots recorded the lowest values. The activity of alkaline phosphatase rose further, especially at a combination of RDF 50 or FYM + biochar (197.4 and 80.4 µgPNPg − 1 soil h − 1 ). The accretive increase between seasons indicates gradual stimulation of phosphorus-changing microbial communities. The overall uniform improvement in phosphatase activity during biochar-based treatment indicates increased phosphorus mobilization in the system. The overall pattern of enzyme activity indicates that biochar, when used in combination with organic manures, significantly enhances soil biological functioning. The increased urease, dehydrogenase, and phosphatase activities indicate that nitrogen and phosphorus cycling is enhanced, as microbial activity and soil functional resilience increase under integrated nutrient management. 3.4 Correlation and scatter plot matrix : Pairwise scatter plots (Fig. 6 a, b) indicated that there were close relationships between the physical, chemical, and biological parameters of soil. A negative correlation between bulk density and porosity was observed, indicating that decreased compaction increased pore space. The positive correlations among organic carbon, porosity, and nutrient availability were strong, underscoring the primary importance of organic carbon in structural stabilization and nutrient retention. The positive correlations between pH, EC, and available phosphorus and potassium indicate that slight changes in soil reaction and ionic strength during biochar treatments were associated with increased nutrient solubility, but not with salinity stress. Moreover, there were strong positive correlations between SOC and biological enzyme activities (urease, dehydrogenase, acid phosphatase, and alkaline phosphatase). Enzyme activities were also positively correlated with the availability of nitrogen and phosphorus. These tendencies indicate that increased carbon inputs and nutrient availability during biochar-based treatments stimulated microbial-mediated nutrient transformations. The intercorrelated patterns of enhanced physical structure, carbon content, nutrient availability, and biological activity in the soil occurred not independently. Nutrient management with biochar as a component of integrated nutrient management thus enhanced the overall quality of soil functions, including structural stabilization and increased nutrient cycling through microbes. 4. Discussion The primary aim of the current study was to investigate biochar and its effects on the soil physico-chemical and biological properties in the Punjab rice-wheat cropping system. One notable finding was that the bulk density was lowest and the porosity was highest in rice husk biochar plots, in line with the prior observations and reports by other researchers that biochar particle size, surface area, and porosity could have a strong impact on the bulk density of soil (Downie et al., 2011 ). Combining 50 per cent RDF, poultry manure, and biochar yielded the greatest reduction in bulk density during rice production. The same changes were observed in plots containing poultry manure alone: bulk density decreased and porosity increased in both years. It is also possible that most of the biochar was more porous, thereby increasing the volume of soil pores and subsequently improving porosity and lowering bulk density (Suliman et al., 2017 ). Such effects are applicable in practice because reduced bulk density enhances water infiltration and retention, as observed by Alghamdi ( 2018 ), who reported high porosity and penetration in plots treated with biochar. Based on modifications to soil physical characteristics, the continuous use of both FYM and vermicompost also decreased the bulk density of wheat, whereas the use of biochar combined with 50% RDF and 50% FYM significantly increased it. The combined effect of FYM, RDF, and biochar on soil organic matter improved soil porosity and reduced bulk density. These findings are consistent with those of Riaz et al. ( 2018 ) and Choudhary et al. ( 2019 ), which indicate that organic matter content is critical in altering soil structural properties. In terms of soil pH and salinity, biochar had an insignificant effect on changes because of its high CEC and buffering capacity in the initial stage, which regulates pH fluctuations (Suliman et al., 2017 ). However, when biochar, poultry manure, and synthetic fertilizers are combined, they can reduce soil salinity by increasing soil pH and CEC. This buffering capacity maintains a constant pH conducive to plant growth. FYM + RDF + biochar significantly affected pH in wheat, likely due to increased CEC and organic matter. The basic cations present in poultry manure and the release of organic anions, including malate and citrate, also helped increase pH, consistent with the results of Novak et al. ( 2016 ). Additionally, the changes in chemical properties were likely influenced by pyrolysis-induced alkaline residues on the biochar surface (Novak et al., 2021 ) and by the presence of Ca, Mg, K, and Na in rice straw. Another indicator of soil solution chemistry, soil electrical conductivity (EC), was great in the first year but was lower in the second year. The trend indicates that nutrient absorption by crops reduced the ion concentration in the soil solution. The enhanced EC during the first year was likely due to nutrient release from the biochar surface, which enabled plant nutrient uptake (Abujabbah et al., 2016; Alkharabsheh et al., 2021 ). Nitrogen availability, an essential component of crop nutrition, was enhanced when biochar was used in combination with poultry manure and synthetic fertilizers. The porous surface of biochar retained nitrogen from applied fertilizers and manure, thereby increasing nitrogen availability to rice crops. Slow decay of organic matter in poultry manure also increased available N. Biochar co-composted with poultry manure exhibited greater nutrient retention, and wheat plots with 50% RDF + 50% FYM + biochar had high N availability. On the other hand, the control plots indicated low nitrogen concentrations, which could have resulted from immobilization and volatilization. In both years, the combined application of biochar, manure, and fertilizers continued to enhance inorganic N availability, presumably through reduced leaching and increased mineralization, consistent with the findings of Oladele et al. ( 2019 ). The use of biochar also increased phosphorus availability. Its strong CEC and surface interactions enhanced plant P retention and uptake, thereby improving soil fertility (Liu et al., 2017 ). Mycorrhizal associations were also promoted by biochar, which enhanced P absorption. Increasing soil pH decreased P sorption, consistent with Cao et al. ( 2020 ), who found higher P levels in biochar-treated soils. FYM, in conjunction with biochar and synthetic fertilizer, was important in the release of P as a result of single superphosphate (SSP) because of the formation of organic acids. Sarfaraz et al. (2020), Jing et al. (2017), and Randolph et al. ( 2017 ) confirmed these observations, stating that biochar and organic amendments act synergistically to increase soil P concentrations. The availability of soil potassium (K) was significantly enhanced by the use of rice straw biochar, FYM, and inorganic fertilizers. Biochar has high K content and is water-soluble; therefore, it demonstrated a substantial increase in K levels relative to the control treatments. In pyrolysis, extractable K is released at temperatures above 600°C (Bilias et al., 2023 ), and plants readily take up this K. FYM provides organic colloids that facilitate K ion exchange. An elevated level of organic matter promotes K mineralization. These results are in line with those of Wang et al. ( 2018 ), Xiu et al. ( 2023 ), and Bilas et al. (2023), who noted that there is a close correlation between organic matter and K dynamics. Organic carbon (SOC) in soils is important for sustaining microbial activity and nutrient storage. Treatments that combined charcoal, manure, and fertilizer produced the highest SOC. Specifically, 50 percent RDF + 50 percent PM + biochar in rice and 50 percent RDF + 50 percent FYM + biochar in wheat showed substantial increases in organic carbon content. Such improvements can be attributed to oxidation of the biochar surface and increased microbial activity during decomposition (Zhang et al., 2021 ). Biochar also enhanced the bond between organic amendments and nitrogen retention and the absorption of organic carbon (Das et al., 2017 ), supporting previous field and laboratory experiments (Ali et al., 2021 ). This higher SOC, in turn, encouraged improved nutrient cycling and aeration (Naeem et al., 2018 ). Urease enzyme activities were the highest in treatments that had 50% RDF + 50% PM + biochar in the rice growing. This rise may be due to enrichment of microbial biomass by organic inputs, as supported by Sakin et al. ( 2021 ) and Pokharel et al. (2021). Consistent with Song et al. ( 2020 ), urease activity also indicates microbial decomposition of organic matter. Wheat showed the greatest activity of urease in the plots and only 50% RDF and 50% FYM + biochar, which may be explained by the higher release of nitrogenous compounds by both the fertilizers and root exudates (Du et al., 2014 ). Enzyme activities are also high in these treatments due to microbial fermentation of the added organic matter. The other important soil biological indicator, which was greatly increased by 50% RDF + 50% FYM+ biochar in wheat and 50% RDF + 50% PM+ biochar in rice was dehydrogenase activity (DHA). This enzyme activity reflects the microbe's overall oxidative processes and is sensitive to organic matter levels. The growth in DHA is consistent with studies by Saha et al. (2021), Sharma et al. ( 2023 ), and Premalatha et al. ( 2023 ), who also reported similar trends in biochar-amended soils. The control and 100% RDF treatments showed the lowest DHA levels, which may be explained by the adverse effects of high salt levels in synthetic fertilisers, which inhibit microbial oxidation capacity (Akumuntu et al., 2024 ). The decreased enzyme activity in these plots could be attributed to increased soil redox potential and increased nitrate accumulation, which inhibit microbial respiration. Phosphorus mineralization was also treatment sensitive through enzyme phosphatase. The activity of acid phosphatase was also significantly higher than that of alkaline phosphatase, likely due to the acidic soil conditions. RDF 50% + FYM 50% + biochar in wheat produced the highest acid phosphatase activity, which may have been caused by a high level of organic carbon and nitrogen (Reddy et al., 2018). This enzyme, along with organic acids produced by FYM decomposition, further enhanced this activity (Durgude et al., 2018 ). These high phosphatase enzyme levels in FYM, VC, and PM+ biochar treatments highlight the role of organic matter in the release of microbial enzymes. The increase in fine roots in biochar-amended soils likely facilitated high levels of enzyme activation through nutrient demand and root exudation. 5. Conclusion Based on the data presented above, it can be concluded that the effects of biochar on soil parameters differed relative to NPK fertilizer and the control group. The research concluded that 50%RDF and 50% poultry manure with biochar is the most appropriate one that can be used on rice fields. This is superior to others in nutrient retention, gas exchange, and pore-space ventilation under submerged conditions. Additionally, it can directly provide nitrogen to rice-wheat crops. A mixture of rice straw biochar, half farmyard manure (FYM), and half RDF is effective for growing upland wheat. This mixture was effective in improving soil physical properties, reducing bulk density, increasing water-holding capacity, and retaining nutrients. Recent studies indicate an increase in soil physical and chemical properties. However, some gains, such as soil bulk density and water retention, were considerably lower than those observed under the control and NPK fertilizer treatments. Biochar-treated plots also had high enzyme activities in the topsoil. The addition of synthetic manure, organic manure, and biochar, namely 50 percent RDF + 50 percent PM + Biochar and 50 percent RDF + 50 percent FYM + Biochar, has resulted in positive changes in the measured soil parameters. This demonstrates the potential of biochar to reduce reliance on synthetic fertilisers and improve soil nutrient-use efficiency. Declarations Conflict of interest: There is no conflict of interest between the authors Competing Interests: The authors have no relevant financial or nonfinancial interests to disclose. Consent to Publish Consent to Publish : Not applicable. Consent to Participate : Not applicable. Ethics Declaration The study involved only cultivated crops (rice and wheat) grown under field conditions. All plant materials were obtained from authorized and certified sources, and cultivation practices complied with the national and local agricultural guidelines of India. No wild plant species were collected, and no specific permissions or licenses were required for the procurement or use of plant materials in this study. Funding: The authors declare that no external funding was received for the conduct of this study or the preparation of this manuscript. Author Contribution Anita Jaswal and Arun Kumar conceived and designed the study. Anita Jaswal and Arshdeep Singh carried out material preparation, field experimentation, and data collection. Data analysis and interpretation were performed by Arun Kumar, Chandra Mohan, Anita Jaswal, and Arshdeep Singh. Arun Kumar and Chandra Mohan provided overall supervision and critical intellectual input. All authors reviewed and approved the final manuscript. Acknowledgement The author gratefully acknowledges the institutional support provided by Lovely Professional University, Punjab, India, and Manipal University Jaipur, India. 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Biochar stability in a highly weathered sandy soil under four years of continuous corn production. Energies. 2021;14:6157. https://doi.org/10.3390/en14196157 . Oladele SO. Effect of biochar amendment on soil enzymatic activities, carboxylate secretions and upland rice performance in a sandy clay loam Alfisol of Southwest Nigeria. Sci Afr. 2019;4:e00107. https://doi.org/10.1016/j.sciaf.2019.e00107 . Oladele S, Adeyemo A, Awodun M, Ajayi A, Fasina A. Effects of biochar and nitrogen fertilizer on soil physicochemical properties, nitrogen use efficiency and upland rice (Oryza sativa) yield grown on an Alfisol in Southwestern Nigeria. Int J Recycl Org Waste Agric. 2019;8:295–308. https://doi.org/10.1007/s40093-019-0251-0 . Olowoboko TB, Azeez JO, Olujimi OO, Babalola OA. Comparative evaluation of animal manures and their ashes on soil pH and electrical conductivity in some Southwestern Nigerian soils. Commun Soil Sci Plant Anal. 2018;49:1442–54. https://doi.org/10.1080/00103624.2018.1464184 . Pokharel P, Ma Z, Chang SX. Biochar increases soil microbial biomass with changes in extra-and intracellular enzyme activities: a global meta-analysis. Biochar. 2020;2:65–79. https://doi.org/10.1007/s42773-020-00039-1 . Premalatha RP, Malarvizhi P, Parameswari E. Effect of biochar doses under various levels of salt stress on soil nutrient availability, soil enzyme activities, and plant growth in a marigold crop. Crop Pasture Sci. 2023;74:66–78. Rahman GM, Rahman MM, Alam MS, Kamal MZ, Mashuk HA, Datta R, Meena RS. Biochar and organic amendments for sustainable soil carbon and soil health. Carbon and nitrogen cycling in soil. Singapore: Springer Singapore; 2019. pp. 45–85. Randolph P, Bansode RR, Hassan OA, Rehrah DJ, Ravella R, Reddy MR, Ahmedna M. Effect of biochars produced from solid organic municipal waste on soil quality parameters. J Environ Manage. 2017;192:271–80. https://doi.org/10.1016/j.jenvman.2017.01.061 . Riaz M, Khan M, Ali S, Khan MD, Ahmad R, Khan MJ, Rizwan M. Sugarcane waste straw biochar and its effects on calcareous soil and agronomic traits of okra. Arab J Geosci. 2018;11:1–7. https://doi.org/10.1007/s12517-018-4113-2 . Sadaf J, Shah GA, Shahzad K, Ali N, Shahid M, Ali S, Rashid MI. Improvements in wheat productivity and soil quality can accomplish by co-application of biochars and chemical fertilizers. Sci Total Environ. 2017;607:715–24. https://doi.org/10.1016/j.scitotenv.2017.06.178 . Sakin E, Ramazanoglu E, Seyrek A. Effects of different biochar amendments on soil enzyme activities and carbon dioxide emission. Commun Soil Sci Plant Anal. 2021;52:2933–44. https://doi.org/10.1080/00103624.2021.1971694 . Sarfraz R, Yang W, Wang S, Zhou B, Xing S. Short-term effects of biochar with different particle sizes on phosphorus availability and microbial communities. Chemosphere. 2020;256:126862. https://doi.org/10.1016/j.chemosphere.2020.126862 . Sharma S, Sharma N, Gupta N, Angmo P, Siddiqui MH, Rahman MA. Impact of Chemically Diverse Organic Residue Amendment on Soil Enzymatic Activities in a Sandy Loam Soil. Agronomy. 2023;13:1719. https://doi.org/10.3390/agronomy13071719 . Singh H, Northup BK, Rice CW, Prasad PV. Biochar applications influence soil physical and chemical properties, microbial diversity, and crop productivity: a meta-analysis. Biochar. 2022;4:8. https://doi.org/10.1007/s42773-022-00138-1 . Song D, Chen L, Zhang S, Zheng Q, Ullah S, Zhou W, Wang X. Combined biochar and nitrogen fertilizer change soil enzyme and microbial activities in a 2-year field trial. Eur J Soil Biol. 2020;99:103212. https://doi.org/10.1016/j.ejsobi.2020.103212 . Sparks DL, Page AL, Helmke PA, Leoppert RH, Soltanpour PN, Tabatabai MA et al. (1996) Methods of soil analysis. Soil Sci Soc Am, Madison, WI, USA, pp. 1011–1069. https://doi.org/10.2136/sssabookser5.3.c5 Subbiah BV, Asija GL. (1956). A rapid procedure for the estimation of available nitrogen in soils. Suliman W, Harsh JB, Abu-Lail NI, Fortuna AM, Dallmeyer I, Garcia-Pérez M. The role of biochar porosity and surface functionality in augmenting hydrologic properties of a sandy soil. Sci Total Environ. 2017;574:139–47. https://doi.org/10.1016/j.scitotenv.2016.09.025 . Toková L, Igaz D, Horák J, Aydin E. Effect of biochar application and re-application on soil bulk density, porosity, saturated hydraulic conductivity, water content, and soil water availability in a silty loam Haplic Luvisol. Agronomy. 2020;10:1005. https://doi.org/10.3390/agronomy10071005 . Walkley A, Black IA. An examination of the Degtjareff method for determining soil organic matter, and a proposed modification of the chromic acid titration method. Soil sci. 1934;37:29–38. Wang L, Xue C, Nie X, Liu Y, Chen F. Effects of biochar application on soil potassium dynamics and crop uptake. J. Plant Nutr Soil Sci. 2018;181:635–43. https://doi.org/10.1002/jpln.201700528 . Watanabe FS, Olsen SR. Test of an ascorbic acid method for determining phosphorus in water and NaHCO3 extracts from soil. Soil Sci Soc Am J. 1965;29:677–8. https://doi.org/10.2136/sssaj1965.03615995002900060025x . Xie X, Pu L, Wang Q, Zhu M, Xu Y, Zhang M. Response of soil physicochemical properties and enzyme activities to long-term reclamation of coastal saline soil, Eastern China. Sci Total Environ. 2017;607:1419–27. Xiu L, Gu W, Sun Y, Wu D, Wang Y, Zhang H, Chen W. The fate and supply capacity of potassium in biochar used in agriculture. Sci Total Environ. 2023;902165969. https://doi.org/10.1016/j.scitotenv.2023.165969 . Yadav NK, Kumar V, Sharma KR, Choudhary RS, Butter TS, Singh G, Kumar R. Biochar and their impacts on soil properties and crop productivity: a review. J Pharmacogn. 2018;Phytochem7:49–54. Zhang Y, Wang J, Feng Y. The effects of biochar addition on soil physicochemical properties: A review. CATENA. 2021;202:105284. https://doi.org/10.1016/j.catena.2021.105284 . Zheng Y, Han X, Li Y, Yang J, Li N, An N. Effects of biochar and straw application on the physicochemical and biological properties of paddy soils in Northeast China. Sci Rep. 2019;9:16531. https://doi.org/10.1038/s41598-019-52978-w . Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 18 Mar, 2026 Reviews received at journal 13 Mar, 2026 Reviews received at journal 12 Mar, 2026 Reviewers agreed at journal 20 Feb, 2026 Reviewers agreed at journal 19 Feb, 2026 Reviewers agreed at journal 18 Feb, 2026 Reviewers invited by journal 18 Feb, 2026 Editor assigned by journal 18 Feb, 2026 Submission checks completed at journal 18 Feb, 2026 First submitted to journal 18 Feb, 2026 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. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8557311","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":594486107,"identity":"046bc744-232c-4ab8-9ef8-69fb3ba01807","order_by":0,"name":"Anita Jaswal","email":"","orcid":"","institution":"Lovely Professional University","correspondingAuthor":false,"prefix":"","firstName":"Anita","middleName":"","lastName":"Jaswal","suffix":""},{"id":594486108,"identity":"5848a3b7-53e8-471e-80c7-a6a33cbc480c","order_by":1,"name":"Chandra Mohan Mehta","email":"","orcid":"","institution":"Lovely Professional University","correspondingAuthor":false,"prefix":"","firstName":"Chandra","middleName":"Mohan","lastName":"Mehta","suffix":""},{"id":594486109,"identity":"d1258016-e617-4929-abfc-987a80b964d6","order_by":2,"name":"Arshdeep Singh","email":"","orcid":"","institution":"Lovely Professional University","correspondingAuthor":false,"prefix":"","firstName":"Arshdeep","middleName":"","lastName":"Singh","suffix":""},{"id":594486110,"identity":"1420662d-17bb-4ff4-9186-0c1a1f412102","order_by":3,"name":"Arun Kumar","email":"data:image/png;base64,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","orcid":"","institution":"Manipal University Jaipur","correspondingAuthor":true,"prefix":"","firstName":"Arun","middleName":"","lastName":"Kumar","suffix":""},{"id":594486111,"identity":"bbd70624-9314-43cb-a784-81663b6e9c7c","order_by":4,"name":"Jayanthi J","email":"","orcid":"","institution":"Manipal University Jaipur","correspondingAuthor":false,"prefix":"","firstName":"Jayanthi","middleName":"","lastName":"J","suffix":""}],"badges":[],"createdAt":"2026-01-09 06:08:32","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8557311/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8557311/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":103213389,"identity":"de5c7667-f2dd-467b-b519-af524815c3b4","added_by":"auto","created_at":"2026-02-23 08:57:39","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":230372,"visible":true,"origin":"","legend":"\u003cp\u003eGeographical location of the experimental Site\u003c/p\u003e","description":"","filename":"1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8557311/v1/ad338dd0127d702bd01f771a.jpg"},{"id":103213377,"identity":"d5fb3d32-8ad4-4818-9833-f72f3ece94e6","added_by":"auto","created_at":"2026-02-23 08:57:32","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":151324,"visible":true,"origin":"","legend":"\u003cp\u003eAverage meteorological data of Phagwara, Punjab, from June 2018 to April 2020\u003c/p\u003e","description":"","filename":"2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8557311/v1/7ff7f14354401b0dea1403a4.jpg"},{"id":103213390,"identity":"d71a3dae-6513-4a53-b833-a69fbbb02b7c","added_by":"auto","created_at":"2026-02-23 08:57:41","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":168439,"visible":true,"origin":"","legend":"\u003cp\u003eFE-SEM image of rice straw biochar\u003c/p\u003e","description":"","filename":"3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8557311/v1/62e80224818ba893497477e3.jpg"},{"id":103213378,"identity":"92b7a758-1da3-4609-8a18-99812bec5725","added_by":"auto","created_at":"2026-02-23 08:57:33","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":165257,"visible":true,"origin":"","legend":"\u003cp\u003e(a, b) and (c, d) represent the effect of biochar-based amendments over two years of cropping system on Urease (mg urea g\u003csup\u003e-1\u003c/sup\u003e soil 24h\u003csup\u003e-1\u003c/sup\u003e) and dehydrogenase (µg TPF/ hr/g soil) activities at different depths. Data shown as mean of S.E. Means with different letters for each fig. are significantly different according to LSD at p\u0026lt;0.05.\u0026nbsp;\u0026nbsp;\u003c/p\u003e","description":"","filename":"4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8557311/v1/f680dcf681235d4093060fdc.jpg"},{"id":103213391,"identity":"6170a51f-9c2f-4eca-b568-74cdcef6a9ce","added_by":"auto","created_at":"2026-02-23 08:57:41","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":159091,"visible":true,"origin":"","legend":"\u003cp\u003e(a, b), (c, d) indicating acid and alkaline phosphatase activities in rice wheat crop at heading stage from different depths. Different symbols above the standard bars indicate that the treatments are statistically different from one another according to DMRT (p \u0026lt; 0.05).\u003c/p\u003e","description":"","filename":"5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8557311/v1/44313bff808a9f1e0ec014df.jpg"},{"id":103213384,"identity":"db878b99-c61f-4d45-9cc2-56d7f416db13","added_by":"auto","created_at":"2026-02-23 08:57:36","extension":"jpg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":216006,"visible":true,"origin":"","legend":"\u003cp\u003e(a):\u003cstrong\u003e \u003c/strong\u003ePairwise scatter plot matrix and histograms showing the distribution and correlation among selected soil physico-chemical parameters: bulk density (BD), porosity, organic carbon (OC), nitrogen (N), phosphorus (P), potassium (K), pH, and electrical conductivity (EC). Diagonal panels show variable distributions, lower panels show bivariate scatter plots, indicating trends and possible relationships among soil attributes. \u003cstrong\u003eFig. 6(b)\u003c/strong\u003ePairwise scatter plot matrix and histograms depicting relationships and distributions among soil chemical and biological properties: organic carbon (OC), nitrogen (N), phosphorus (P), potassium (K), urease activity, dehydrogenase activity (DHA), acid phosphatase (ACP), and alkaline phosphatase (ALP). Diagonal panels show frequency distributions, while lower panels illustrate bivariate relationships highlighting potential correlations between nutrient availability and enzyme activities.\u003c/p\u003e","description":"","filename":"6.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8557311/v1/dd9790ca3a3cfbffc8d2be67.jpg"},{"id":103505977,"identity":"b8b42dd1-c66e-42b1-8e73-a92cc089f7aa","added_by":"auto","created_at":"2026-02-26 13:33:42","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2258952,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8557311/v1/3b8856b1-c2e1-45e3-86b6-d036046d7ca5.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Biochar-Based Integrated Nutrient Management Improves Soil Quality and Biological Functioning in a Rice–Wheat Cropping System","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eOne of the most useful and strategically significant agroecosystems in South Asia is the rice-wheat system of the Indo-Gangetic Plains (IGP), which provides food security for hundreds of millions of people. High-yielding varieties, irrigation, and intensive use of mineral fertilizers have been the foundation of this system since the Green Revolution, maintaining the same level of production (Lal, 2016; Zhang et al., 2021). Although remarkable gains in yields have been achieved through these practices, continuous cultivation over extended periods, limited crop diversification, and the systematic eradication or burning of crop remnants have increasingly altered the physical organization of soils, nutrient cycling, and biological processes. The reduction in soil organic carbon (SOC) stocks has become a major concern, as SOC supports aggregation, water retention, nutrient buffering, and microbial habitat stability (Naeem et al., 2018; Bashir et al., 2021). Carbon and water loss are common, and structural degradation, decreased porosity, compaction, and a lower cation-exchange potential that limit root growth and nutrient uptake contribute to SOC loss. Moreover, organic matter degradation reduces soil resilience to temperature and variable precipitation, thereby increasing the degree of unpredictability under climate variability (Brempong et al., 2023). Although mineral fertilizers will always be necessary to meet crop nutrient demands, prolonged exclusive use of them contributes to nutrient imbalances, low nutrient-use efficiency, soil acidification or alkalization, and inhibition of beneficial microflora (Gul et al., 2015; Das et al., 2017). As a result, the restriction in soil fertility of intensive rice-wheat systems is increasingly linked not only to nutrient deficiencies but also to impaired soil functioning, specifically to interference with carbon-mediated nutrient-cycling mechanisms (Lal, 2016). The combination of organic and inorganic inputs, which constitute integrated nutrient management strategies, has consequently become a subject of renewed interest as a means of replenishing soil quality while remaining productive. Organic amendments provide labile carbon fractions that promote microbial activity and aggregation, including farmyard manure, Vermicompost, and poultry manure. However, these materials are readily degraded under subtropical climate conditions, resulting in temporary advantages and insufficient long-term carbon stabilization (He et al., 2017). It is then inferred that the required carbon inputs must be not only biologically interactive but also structurally persistent. This has been one of the promising candidates, the biochar. Biological material is converted to biomass via pyrolysis, which is conducted under low oxygen conditions. It is characterized by the presence of aromatic carbon, a high surface area, an uneven charge distribution, and high density (Kamau et al., 2019; Singh et al., 2022). Such physicochemical properties can be used to modify soil processes in various ways. First, it is porous, which enhances soil water retention and aeration. Second, the surface functional groups enhance cation-exchange capacity, thereby increasing nutrient retention and reducing leaching losses. Third, biochar-derived carbon is relatively recalcitrant, resulting in long-term stabilization of SOC and potential carbon sequestration (He et al., 2017). Biochar also interacts with soil biological systems, in addition to its physical and chemical effects. It may act as a protective microhabitat for microorganisms, regulate pH, and influence enzyme-mediated nutrient changes (Juriga et al., 2018). It has been reported that microbial biomass and enzyme activity increase with biochar application, particularly with nutrient inputs (Lusiba et al., 2017). However, the agronomic response of biochar is unpredictable because it is typically low in readily available nutrients. That is why it appears to be particularly promising when combined with mineral fertilizers and organic manures (Oladele et al., 2019; Yadav et al., 2018). Biochar could synergize with reduced doses of mineral fertilizers and organic additives (Hu et al., 2024). Although mineral fertilizers are abundant in readily available nutrients, organic manure contains labile carbon that enhances microbial activity, and biochar contains a stable carbon skeleton that enhances nutrient retention and habitat formation (Rahman et al., 2019). Such interactions are able to increase nutrient recovery, phosphorus through adsorption and desorption, and potassium retention, with the net effect being the optimisation of the nutrient cycling in the soil system. Additionally, SOC and aggregation may be improved to mitigate the trend toward increased bulk density, which frequently accompanies intensive cropping (Du et al., 2017). Despite an emerging literature body on biochar worldwide, very few field-based studies have been carried out on long-term rotation of rice-wheat in Punjab. A large share of the existing literature focuses on short-term laboratory results or on evaluating impacts within a single season, and this may be insufficient to test the potential cumulative effects on soil carbon interactions and enzyme activities. In particular, the impact of biochar-based nutrient management on relevant soil enzyme indicators (urease, dehydrogenase, acid phosphatase, and alkaline phosphatase) under subtropical field conditions remains poorly studied. These enzymes are directly associated with the mineralization of nitrogen, respiration, and cycling of phosphorus by microorganisms; therefore, they are considered as helpful indicators of soil biosphere and phosphorus transformation efficacy (Jian et al., 2016). A better method for assessing soil functional recovery is to examine enzyme activity and physicochemical parameters (Xie et al., 2017). Changes in bulk density, porosity, pH, and nutrient availability should be analyzed in conjunction with biological indicators to determine whether the implementation of integrated nutrient management methods is likely to increase overall soil resilience without increasing nutrient availability. Furthermore, with increasing attention to mitigating climate change and sustainable intensification, the agronomic and environmental significance of biochar-based systems for carbon stabilization and nutrient-use efficiency warrants consideration (Lal, 2016; Brempong et al., 2023). Therefore, the present study was conducted to assess the effects of biochar produced from rice straw, along with organic and inorganic nutrient sources, on the physicochemical characteristics of soils, nutrient status, and biological indicators in a rice-wheat growing system in Punjab. It was hypothesized that complete replacement of mineral fertilizers with organic manures in the existence of biochar would (i) raise the accumulation of SOC and structural stability, (ii) raise nutrient retention and availability, (iii) boost soil enzymatic activity as indicative of improved biological functioning and (iv) boost a more sustainable and climate-resilient nutrient management system in intensive cereal system.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eRelevance to Sustainable Development\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eRice-wheat cropping systems in South Asia face the double burden of deteriorating soil quality and environmentally unsustainable residue management practices. The use of excess rice straw as biochar is a nature-based solution that can mitigate open-field burning, improve nutrient-use efficiency, and sequester soil organic carbon. These approaches directly address the global SDGs 2.4 (sustainable food production systems), 12.5 (substantial reduction of waste through recycling), and 13.2 (climate change mitigation actions). Thus, the assessment of biochar in the context of integrated nutrient management is not only an agronomic issue but also an imperative of sustainability.\u0026nbsp;\u003c/p\u003e"},{"header":"2. Materials and methods","content":"\u003cp\u003e\u003cb\u003e2.1 Experiment Location and Conditions\u003c/b\u003e: The field study was conducted for two consecutive years (July 2018-April 2020) at the Crop Research Centre of the Department of Agronomy, Lovely Professional University, Phagwara, Punjab, India. The experimental farm is situated in the Trans-Gangetic Plains at approximately 31\u0026deg;24\u0026prime; N latitude and 75\u0026deg;69\u0026prime; E longitude, with an average elevation of approximately 245 m amsl. A semi-arid subtropical climate and a distinct monsoon season characterize the area. The average maximum summer temperatures often touch about 42\u0026deg;C, whereas winter minimum temperatures sometimes drop to as low as 6\u0026deg;C. The average annual rainfall in the region is approximately 800 mm, with the majority occurring from July to September during the southwest monsoons. Isolated rainfall also occurs from December to April due to western disturbances. In the experimental time, the total rainfall was 199.8 mm, and seasonal temperatures ranged from 5\u0026deg;C to 21\u0026deg;C. The farm has been managed following integrated farming systems since 2010. The soil type-\u003cem\u003eTypic Haplustept\u003c/em\u003e with a sandy loam texture, moderate drainage, and low to medium fertility. Before the experiment was implemented, the land had been used for several years in a conventional rice-wheat crop rotation, which is prevalent in central Punjab.\u003c/p\u003e\u003cp\u003e\u003cb\u003e2.2 Plant material and source\u003c/b\u003e- The plant materials used in the study included rice (\u003cem\u003eOryza sativa\u003c/em\u003e L., cv. Pusa Basmati 1121) and wheat (\u003cem\u003eTriticum aestivum\u003c/em\u003e L., cv. PBW 550). Certified seeds of both crops were procured from authorized agricultural sources recommended by the Punjab Agricultural University (PAU), Ludhiana. The crops were cultivated under field conditions at the Agronomy Research Farm, Lovely Professional University, Phagwara, Punjab, India (31\u0026deg;24\u0026prime; N latitude, 75\u0026deg;69\u0026prime; E longitude). No wild plant material was collected for this study.\u003c/p\u003e\u003cp\u003e\u003cb\u003e2.3 Experimental details\u003c/b\u003e: The field investigation was conducted for two consecutive cropping cycles, encompassing the Kharif and Rabi seasons of 2018\u0026ndash;19 and 2019\u0026ndash;20. The study evaluated nine nutrient management treatments to assess the individual and combined effects of mineral fertilizer, biochar, and organic amendments. The treatments included: (i) an unfertilized control, (ii) 100% recommended dose of fertilizer (RDF), and (iii\u0026ndash;viii) combinations of 50% RDF integrated with biochar and varying proportions (25% or 50%) of farmyard manure (FYM), vermicompost (VC), or poultry manure (PM). For the rice crop, the recommended fertilizer dose (RDF) was 42:30:30 kg ha⁻\u0026sup1; of N: P₂O₅: K₂O. Organic amendments were applied at the following rates: FYM at 12.5 t ha⁻\u0026sup1;, vermicompost at 1 t ha⁻\u0026sup1;, poultry manure at 2 t ha⁻\u0026sup1;, and rice straw\u0026ndash;derived biochar at 10 t ha⁻\u0026sup1;. For the succeeding wheat crop, RDF was applied at 120:60:60 kg ha⁻\u0026sup1; of N: P₂O₅:K₂O, with FYM (10 t ha⁻\u0026sup1;), vermicompost (2.5 t ha⁻\u0026sup1;), and poultry manure (6 t ha⁻\u0026sup1;) adjusted according to crop requirement recommendations of Punjab Agricultural University (PAU), Ludhiana.\u003c/p\u003e\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eAll organic inputs were incorporated on a dry-weight basis during final land preparation to ensure uniform mixing within the soil. Mineral fertilizers were supplied through urea (N source), single superphosphate and diammonium phosphate (P sources), and muriate of potash (K source). Phosphorus and potassium were applied entirely as basal doses, whereas nitrogen was split, with half applied at sowing/transplanting and the remainder at critical crop growth stages. The biochar used in the experiment was produced from rice straw via pyrolysis. It exhibited an alkaline reaction (pH 8.94) and low electrical conductivity (0.07 dS m⁻\u0026sup1;). The material contained 396 g kg⁻\u0026sup1; total carbon, 4.08 g kg⁻\u0026sup1; total nitrogen, 738 mg kg⁻\u0026sup1; total phosphorus, and 8.35 g kg⁻\u0026sup1; total potassium. Physical properties included a bulk density of 0.117 g cm⁻\u0026sup3;, particle density of 0.273 g cm⁻\u0026sup3;, total porosity of 60.07%, solid space of 39.9%, and ash content of 37.6%. Microstructural characteristics of the biochar were examined using electron microscopy at the Central Instrumentation Facility, Lovely Professional University (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cb\u003e2.4 Crop management\u003c/b\u003e: The experiment was conducted on the growth of rice in the kharif season and wheat in the rabi season as per the recommended agronomic practices of Punjab Agricultural University. For rice, nursery beds were raised 30 days prior to transplanting, and 25-day-old seedlings of the cv. Pusa Basmati 1121 was transplanted in puddled fields at a spacing of 20 \u0026times; 15 cm. Puddling was performed with a tractor-operated rotavator in standing water to form a homogeneous muddy layer favorable for seedling establishment. Wheat variety PBW-550 was planted after harvesting the rice crop by manual seed drill at a depth of 3\u0026ndash;5 cm with a row spacing of 22 cm and plant spacing of 5\u0026ndash;7 cm. The wheat seed rate was maintained at 120 kg ha⁻\u0026sup1;. Intercultural operations, including irrigation, weed management, and plant protection, were performed equally across all treatments in accordance with the regional package of practices. Rice was harvested by hand with sickles in November, when the grains had attained physiological maturity and a moisture content of approximately 25%. Threshing was done after sun drying to 12\u0026ndash;14% moisture content. Wheat harvesting occurred in late April when the crop turned golden yellow, and threshing was done plot-wise by beating the crop bundles on a drum. All crop residues, except those used for biochar production, were removed from the plots to ensure uniformity.\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003e \u003cb\u003e2.5 Soil physico-chemical Analysis\u003c/b\u003e: Before sowing and after harvest at the end of every season, composite soil samples (015 cm deep) were collected. The samples were air-dried, sieved (2 mm), and analyzed using standard procedures for physicochemical property determination. The pH and electrical conductivity were measured in a soil-water suspension. The Walkley-Black wet oxidation procedure was used to determine soil organic carbon. Nitrogen, phosphorus, and potassium were determined by standard alkaline KMnO4 distillation (Subbiah \u0026amp; Asija,1956), Olsen extraction (Olsen et al., 1956; Jackson, 1991), and flame photometry (Blake \u0026amp; Hartage, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e1986\u003c/span\u003e), respectively, in accordance with standard soil analysis protocols. The core method was used to measure bulk density, and the values of bulk and particle density were used to calculate porosity\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003e \u003cb\u003e2.6 Soil enzymes assay\u003c/b\u003e: Dehydrogenase activity was estimated using the triphenyl tetrazolium chloride (TTC) reduction method, and results were expressed as \u0026micro;g TPF g⁻\u0026sup1; soil day⁻\u0026sup1; (\u003cb\u003eTatabati, 1982\u003c/b\u003e). Urease activity was determined by measuring ammonium release following urea hydrolysis (McGarity \u0026amp; Myers, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e1967\u003c/span\u003e). Acid and alkaline phosphatase activities were measured using p-nitrophenyl phosphate as the substrate under appropriate buffered conditions (Tata \u0026amp; Bremner, 1969). Enzyme activities were expressed on a dry-soil basis, following standard procedures reported in the soil enzymology literature.\u003c/p\u003e \u003cp\u003e \u003cb\u003e2.7 Statistical analysis\u003c/b\u003e: The data were analyzed using analysis of variance (ANOVA) with SPSS version 20.0 statistical software program (SPSS Inc.). The means were then compared using Duncan's multiple-range test. The results were reported as the mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation, with significance at \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026le;\u0026thinsp;0.05.\u003c/p\u003e "},{"header":"3. Results","content":"\u003cp\u003e \u003cb\u003e3.1 Impact of Biochar combined fertilizers on soil physico-chemical properties\u003c/b\u003e: Treatment did not have a significant effect on bulk density or porosity in each of the two years of experimentation (p \u0026gt; 0.05); nevertheless, some consistent numerical patterns were noticeable. Biochar-amended plots tended to have less bulk density than control and sole RDF in both years after the rice harvest (Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e). Following the initial crop season, bulk density was found to be 1.74–1.85 g cm\u003csup\u003e− 1\u003c/sup\u003e, and the values in the conditions of integrated biochar were relatively lower. In the second year, the changes were more moderate, indicating that structures became gradually more stable rather than changing suddenly due to changes in soil compaction. The control plots showed similar bulk density across seasons, suggesting little structural enhancement with mineral fertilizer alone. This was likewise witnessed with the bulk density of 1.791.87 g cm -1 (202021) and 1.751.85 g cm -1 (202122) in wheat cultivation. Although the difference was not statistically significant, a steady decrease with biochar-based treatment suggests increased aggregation and greater pore connectivity, likely due to the porous structure and low particle density of biochar. There was no significant difference in the porosity between treatments; nevertheless, biochar-integrated plots displayed a consistently small (but significantly higher porosity than control and 100 percent RDF treatments. These quantitative gains suggest slow changes in soil physical properties, possibly due to increased aggregation and reduced compaction effects under integrated nutrient management.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\u003cdiv class=\"gridtable\"\u003e\u003cdiv align=\"left\" class=\"colspec\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\"\u003e\u003c/div\u003e\u003ctable id=\"Tab1\" border=\"1\"\u003e \u003ccaption\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eEffect of biochar -based amendments on soil physical properties (mean ± S.E) over Two Years in a rice–wheat cropping system.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"9\"\u003e \u003c/colgroup\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"2\"\u003e \u003cp\u003e2018–2019 (Rice)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\"\u003e \u003cp\u003e2018–2019 (Wheat)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\"\u003e \u003cp\u003e2019–2020 (Rice)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\"\u003e \u003cp\u003e2019–2020 (Wheat)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eTreatments\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eBulk density (g/cm³)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003ePorosity (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eBulk density (g/cm³)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003ePorosity (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eBulk density (g/cm³)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003ePorosity%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eBulk density (g/cm³)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003ePorosity%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eT\u003csub\u003e0\u003c/sub\u003e-Control (no fertilizer)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.83 ± 0.06a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e24.77 ± 4.83a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.87 ± 0.12a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e26.87 ± 8.46a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.82 ± 0.09a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e25.10 ± 10.54a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.85 ± 0.18a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e29.1 ± 7.87a\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eT\u003csub\u003e1\u003c/sub\u003e-100%RDF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.85 ± 0.06a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e25.4 ± 7.37a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.84 ± 0.15a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e27.50 ± 5.68a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.86 ± 0.08a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e25.6 ± 9.17a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.83 ± 0.15a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e30.53 ± 6.63a\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eT\u003csub\u003e2\u003c/sub\u003e- 50%RDF + Biochar\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.82 ± 0.10a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e26.67 ± 7.4a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.82 ± 0.15a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e28.9 ± 8.37a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.80 ± 0.13a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e27.23 ± 3.96a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.80 ± 0.18a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e31.3 ± 7.06a\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eT\u003csub\u003e3\u003c/sub\u003e-50%RDF + 25%FYM+Biochar\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.80 ± 0.14a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e27.23 ± 8.7a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.83 ± 0.22a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e30.03 ± 12.11a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.77 ± 0.10a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e29.3 ± 4.98a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.79 ± 0.14a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e32.2 ± 10.3a\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eT\u003csub\u003e4\u003c/sub\u003e-50%RDF + 50%FYM+Biochar\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.78 ± 0.13a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e29.7 ± 6.86a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.79 ± 0.17a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e34.70 ± 12.16a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.75 ± 0.17a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e31.10 ± 8.81a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.75 ± 0.16a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e35.6 ± 10.9a\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eT\u003csub\u003e5\u003c/sub\u003e-50%RDF + 25%Vermi-compost + Biochar\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.79 ± 0.09a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e29.93 ± 7.54a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.82 ± 0.11a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e31.57 ± 10.11a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.77 ± 0.09a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e28.00 ± 8.25a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.80 ± 0.18a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e33.8 ± 10.53a\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eT\u003csub\u003e6\u003c/sub\u003e-50%RDF + 50%Vermi compost+ Biochar\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.76 ± 0.12a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e29.07 ± 9.25a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.81 ± 0.06a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e33.53 ± 8.33a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.74 ± 0.21a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e31.67 ± 12.45a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.77 ± 0.22a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e34.6 ± 6.85a\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eT\u003csub\u003e7\u003c/sub\u003e-50%RDF + 25%Poultry manure+ Biochar\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.78 ± 0.15a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e29.83 ± 7.14a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.79 ± 0.13a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e32.94 ± 6.73a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.73 ± 0.20a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e30.50 ± 6.6a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.78 ± 0.24a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e33.03 ± 4.19a\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eT\u003csub\u003e8\u003c/sub\u003e-50%RDF + 50%Poultry manure+ Biochar\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.74 ± 0.12a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e30.03 ± 8.44a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.82 ± 0.13a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e33.53 ± 4.78a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.70 ± 0.26a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e33.53 ± 9.51a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.77 ± 0.13a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e34.65 ± 5.91a\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"9\"\u003e*The figures represented are the average of three replications. ± S.E is the standard error of the mean. Means that differ substantially among treatments are denoted by various letters in superscripts. Note- RDF- Recommended dose of fertilizer, FYM- farm yard manure,\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003cp\u003e\u003c/p\u003e \u003cp\u003eThere was relative stability in soil pH across treatments and seasons, indicating that the soil's buffering capacity was high, given its sandy loam texture. However, biochar treatments exhibited higher pH values. The highest pH (7.10) was measured in 50 percent RDF + 50 percent poultry manure + biochar, whereas the lowest pH (6.93) was in the control and in RDF alone (Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e). The same pattern persisted during the wheat season, with 50% RDF + 50% FYM + biochar yielding slightly higher pH values (7.12, 7.14). These marginal improvements can be explained by the fact that rice straw biochar is alkaline and contains ash that can neutralize soil acidity and increase base saturation. However, the small magnitude of change indicates that biochar had little to no effect on soil pH, beyond stabilizing it.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\u003cdiv class=\"gridtable\"\u003e\u003cdiv align=\"left\" class=\"colspec\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\"\u003e\u003c/div\u003e\u003ctable id=\"Tab2\" border=\"1\"\u003e \u003ccaption\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eEffect of biochar -based amendments on soil chemical properties (mean ± S.E) over Two Years in a rice–wheat cropping system.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"9\"\u003e \u003c/colgroup\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"2\"\u003e \u003cp\u003e2018–2019 (Rice)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\"\u003e \u003cp\u003e2018–2019 (Wheat)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\"\u003e \u003cp\u003e2019–2020 (Rice)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\"\u003e \u003cp\u003e2019–2020 (Wheat)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eTreatments\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003epH\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eEC dSm\u003csup\u003e− 1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003epH\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eECdSm\u003csup\u003e− 1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003epH\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eEC dSm\u003csup\u003e− 1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003epH\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eEC dSm\u003csup\u003e− 1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eT\u003csub\u003e0\u003c/sub\u003e-Control (no fertilizer)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e6.93 ± 0.07a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.216 ± 0.013a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e6.94 ± 0.11a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.218 ± 0.023a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e6.94 ± 0.11a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.217 ± 0.007a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e6.95 ± 0.25a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.219 ± 0.021ab\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eT\u003csub\u003e1\u003c/sub\u003e-100%RDF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e6.96 ± 0.10a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.217 ± 0.013a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e6.97 ± 0.26a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.220 ± 0.009a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e6.97 ± 0.10a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.219 ± 0.014a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e6.98 ± 0.19a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.222 ± 0.010ab\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eT\u003csub\u003e2\u003c/sub\u003e- 50%RDF + Biochar\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e6.98 ± 0.10a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.219 ± 0.014a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e7.00 ± 0.27a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.222 ± 0.008a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e7.00 ± 0.08a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.221 ± 0.007a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e7.01 ± 0.29a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.224 ± 0.011ab\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eT\u003csub\u003e3\u003c/sub\u003e-50%RDF + 25%FYM+Biochar\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e7.03 ± 0.14a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.221 ± 0.013a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e7.02 ± 0.14a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.223 ± 0.016a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e7.02 ± 0.14a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.223 ± 0.014a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e7.06 ± 0.16a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.226 ± 0.013a\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eT\u003csub\u003e4\u003c/sub\u003e-50%RDF + 50%FYM+Biochar\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e7.05 ± 0.17a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.223 ± 0.009a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e7.12 ± 0.09a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.230 ± 0.008a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e7.06 ± 0.17a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.225 ± 0.016a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e7.14 ± 0.16a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.233 ± 0.010a\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eT\u003csub\u003e5\u003c/sub\u003e-50%RDF + 25%Vermi-compost + Biochar\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e7.02 ± 0.07a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.219 ± 0.009a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e7.04 ± 0.13a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.226 ± 0.009a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e7.04 ± 0.08a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.220 ± 0.010a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e7.08 ± 0.21a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.229 ± 0.013a\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eT\u003csub\u003e6\u003c/sub\u003e-50%RDF + 50%Vermi compost+ Biochar\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e7.04 ± 0.13a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.221 ± 0.014a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e7.08 ± 0.09a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.228 ± 0.013a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e7.06 ± 0.15a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.223 ± 0.017a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e7.11 ± 0.17a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.231 ± 0.010a\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eT\u003csub\u003e7\u003c/sub\u003e-50%RDF + 25%poultry manure+ Biochar\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e7.07 ± 0.18a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.222 ± 0.011a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e7.05 ± 0.15a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.223 ± 0.010a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e7.09 ± 0.15a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.224 ± 0.013a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e7.07 ± 0.15a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.227 ± 0.06a\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eT\u003csub\u003e8\u003c/sub\u003e-50%RDF + 50%poultry manure+ Biochar\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e7.10 ± 0.17a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.226 ± 0.018a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e7.10 ± 0.11a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.225 ± 0.017a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e7.12 ± 0.17a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.228 ± 0.018a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e7.12 ± 0.34a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.228 ± 0.017a\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"9\"\u003e*The figures represented are the average of three replications. ± S.E is the standard error of the mean. Different superscripts denote the means that differ substantially among treatments. Note- RDF- Recommended dose of fertilizer, FYM- farm yard manure,\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003cp\u003e\u003c/p\u003e \u003cp\u003eElectrical conductivity (EC) differed substantially among treatments within the 2021 rice season. The EC increased with biochar under organic manures, particularly with 50% RDF + 50% poultry manure + biochar (0.226 dS m\u003csup\u003e− 1\u003c/sup\u003e), and was statistically similar to the FYM-integrated treatment (0.223 dS m\u003csup\u003e− 1\u003c/sup\u003e). The lowest EC values were observed in the control and sole RDF treatments. This trend was repeated in further wheat seasons when biochar-manure combinations always displayed a relatively higher value of EC. The EC increase was likely due to improved nutrient retention and availability, as the values were within the safe agronomic range. Taken together, these findings suggest that the integration of biochar had a modest but positive effect on soil structural and chemical buffering, but did not cause significant adverse effects on salinity.\u003c/p\u003e \u003cp\u003e \u003cb\u003e3.2 Impact of Biochar combined fertilizers on soil nutrient status\u003c/b\u003e: There was a substantial increase in soil nutrient availability under biochar-based nutrient management (p \u0026lt; 0.05). After rice harvest, the greatest amount of nitrogen was found at less than 50% RDF + 50% poultry manure + biochar (562.6 and 560.5 kg ha\u003csup\u003e− 1\u003c/sup\u003e in a two-year-old cultivated field), and the least amount at the control (276.0 and 281.3 kg ha\u003csup\u003e− 1\u003c/sup\u003e) (Tables\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e and \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e). The scope of growth indicates improved nitrogen storage and mineralization under mixed treatment conditions with organic and biochar. The porous nature of biochar could have minimized nitrogen loss via leaching or volatilization and, at the same time, enhanced mineralization by microorganisms. Maximum available nitrogen moved slightly toward the 50% RDF + 50% FYM + biochar treatment (563.8 and 566.3 kg ha\u003csup\u003e− 1\u003c/sup\u003e) during the wheat season, after which the vermicompost-integrated treatments ranked second. This seasonal change is likely related to variations in decomposition rates and nutrient release patterns from organic inputs, and FYM provides a more long-term nitrogen supply due to cooler wheat-growing conditions.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\u003cdiv class=\"gridtable\"\u003e\u003cdiv align=\"left\" class=\"colspec\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\"\u003e\u003c/div\u003e\u003ctable id=\"Tab3\" border=\"1\"\u003e \u003ccaption\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eEffect of biochar-based amendments on soil nutrient status (mean ± S.E) of rice crop during both years\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"9\"\u003e \u003c/colgroup\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"4\"\u003e \u003cp\u003e2018–2019 (Rice)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"4\"\u003e \u003cp\u003e2019–2020 (Rice)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eTreatments\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eAvailable N kg ha-1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eAvailable P kgha\u003csup\u003e− 1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eAvailable K kgha\u003csup\u003e− 1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eOC (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eAvailable N kg ha-1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eAvailable P kgha\u003csup\u003e− 1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eAvailable K kgha\u003csup\u003e− 1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eOC (%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eT\u003csub\u003e0\u003c/sub\u003e-Control (no fertilizer)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e276.00 ± 1.63g\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e6.39 ± 0.06g\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e244.77 ± 2.68g\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.58 ± 0.02i\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e281.37 ± 1.29h\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e6.65 ± 0.17g\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e240.23 ± 0.86h\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.59 ± 0.02g\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eT\u003csub\u003e1\u003c/sub\u003e-100%RDF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e461.23 ± 0.86f\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e13.87 ± 0.25h\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e309.00 ± 0.82f\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.64 ± 0.02h\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e466.43 ± 1.14g\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e14.84 ± 0.26f\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e305.67 ± 1.23g\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.66 ± 0.01f\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eT\u003csub\u003e2\u003c/sub\u003e- 50%RDF + Biochar\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e482.28 ± 0.88e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e17.20 ± 0.29f\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e314.33 ± 0.98e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.71 ± 0.01g\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e480.23 ± 0.71f\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e20.36 ± 0.18e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e311.93 ± 1.27f\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.76 ± 0.01e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eT\u003csub\u003e3\u003c/sub\u003e-50%RDF + 25%FYM+Biochar\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e518.00 ± 1.63d\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e19.40 ± 0.37e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e337.03 ± 0.74d\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.87 ± 0.01f\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e522.77 ± 1.93d\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e20.52 ± 0.14e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e335.00 ± 1.36e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.89 ± 0.02d\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eT\u003csub\u003e4\u003c/sub\u003e-50%RDF + 50%FYM+Biochar\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e551.97 ± 1.59b\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e21.77 ± 0.21c\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e345.90 ± 1.28c\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.01 ± 0.01c\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e552.77 ± 1.11b\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e22.67 ± 0.07d\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e344.30 ± 0.70c\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.04 ± 0.02b\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eT\u003csub\u003e5\u003c/sub\u003e-50%RDF + 25%Vermi-compost + Biochar\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e519.97 ± 1.49c\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e20.17 ± 0.29d\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e335.00 ± 1.31d\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.91 ± 0.01e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e520.17 ± 0.87e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e20.63 ± 0.04c\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e333.43 ± 0.76e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.95 ± 0.02c\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eT\u003csub\u003e6\u003c/sub\u003e-50%RDF + 50%Vermi compost+ Biochar\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e548.53 ± 1.70c\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e21.53 ± 0.25c\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e343.73 ± 1.32c\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.96 ± 0.01d\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e544.83 ± 2.37d\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e21.63 ± 0.10d\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e340.57 ± 0.82d\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.97 ± 0.02c\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eT\u003csub\u003e7\u003c/sub\u003e-50%RDF + 25%poultry manure+ Biochar\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e553.37 ± 0.95b\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e24.03 ± 0.40b\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e354.20 ± 1.66b\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.06 ± 0.01b\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e556.17 ± 1.55b\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e23.87 ± 0.21b\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e350.13 ± 1.17b\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.05 ± 0.01b\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eT\u003csub\u003e8\u003c/sub\u003e-50%RDF + 50%poultry manure+ Biochar\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e562.60 ± 1.28a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e24.93 ± 0.69a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e365.07 ± 0.74a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.20 ± 0.01a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e560.53 ± 1.11a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e25.13 ± 0.05a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e360.70 ± 1.16a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.16 ± 0.03a\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"9\"\u003e*The figures represented are the average of three replications. ± S.E is the standard error of the mean. Different superscripts denote the means that differ substantially among treatments. Note- RDF- Recommended dose of fertilizer, FYM- farm yard manure,\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003cp\u003e\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\u003cdiv class=\"gridtable\"\u003e\u003cdiv align=\"left\" class=\"colspec\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\"\u003e\u003c/div\u003e\u003ctable id=\"Tab4\" border=\"1\"\u003e \u003ccaption\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eEffect of biochar-based amendments on soil nutrient status (mean ± S.E) of wheat crop during both years\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"9\"\u003e \u003c/colgroup\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"4\"\u003e \u003cp\u003e2018–2019 Wheat\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"4\"\u003e \u003cp\u003e2019–2020 Wheat\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eTreatments\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eAvailable N kg ha-1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eAvailable P kgha\u003csup\u003e− 1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eAvailable K kgha\u003csup\u003e− 1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eOC (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eAvailable N kgha\u003csup\u003e− 1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eAvailable P kgha\u003csup\u003e− 1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eAvailable K kgha\u003csup\u003e− 1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eOC (%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eT\u003csub\u003e0\u003c/sub\u003e-Control (no fertilizer)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e284.7 ± 1.93h\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e7.15 ± 0.03h\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e238.33 ± 0.68i\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.60 ± 0.02h\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e290.67 ± 1.25g\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e7.64 ± 0.24h\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e240.40 ± 1.18i\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.62 ± 0.02i\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eT\u003csub\u003e1\u003c/sub\u003e-100%RDF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e475.3 ± 1.25g\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e21.17 ± 0.29g\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e312.90 ± 0.99h\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.79 ± 0.02g\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e477.67 ± 2.05f\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e22.55 ± 0.10g\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e316.37 ± 1.68h\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.82 ± 0.02h\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eT\u003csub\u003e2\u003c/sub\u003e- 50%RDF + Biochar\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e493.60 ± 1.10f\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e22.23 ± 0.25f\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e339.43 ± 0.70g\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.94 ± 0.01f\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e496.00 ± 1.63e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e23.56 ± 0.28f\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e338.73 ± 1.03g\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e0.96 ± 0.02g\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eT\u003csub\u003e3\u003c/sub\u003e-50%RDF + 25%FYM+Biochar\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e523.80 ± 1.07e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e25.57 ± 0.21c\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e368.20 ± 0.82d\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.17 ± 0.02d\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e525.00 ± 2.16d\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e26.34 ± 0.15c\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e370.77 ± 1.29d\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.22 ± 0.02d\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eT\u003csub\u003e4\u003c/sub\u003e-50%RDF + 50%FYM+Biochar\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e563.80 ± 1.19a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e27.23 ± 0.29a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e386.23 ± 0.82a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.45 ± 0.02a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e566.33 ± 1.25a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e28.52 ± 0.32a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e387.80 ± 1.36a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.52 ± 0.02a\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eT\u003csub\u003e5\u003c/sub\u003e-50%RDF + 25%Vermi-compost + Biochar\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e544.37 ± 0.70d\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e24.77 ± 0.37d\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e363.37 ± 0.98e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.12 ± 0.01e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e548.0 ± 1.63c\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e25.48 ± 0.27d\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e365.27 ± 1.72e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.17 ± 0.01e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eT\u003csub\u003e6\u003c/sub\u003e-50%RDF + 50%Vermi compost+ Biochar\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e562.57 ± 1.27ab\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e26.67 ± 0.34b\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e377.90 ± 1.20b\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.32 ± 0.01b\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e564.67 ± 1.25a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e27.60 ± 0.18b\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e380.37 ± 1.52b\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.38 ± 0.01b\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eT\u003csub\u003e7\u003c/sub\u003e-50%RDF + 25%poultry manure+ Biochar\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e557.80 ± 0.49c\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e24.03 ± 0.17e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e356.13 ± 0.82f\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.10 ± 0.01e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e560.67 ± 1.25b\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e24.61 ± 0.19e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e360.17 ± 1.42f\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.14 ± 0.02f\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\"\u003e \u003cp\u003eT\u003csub\u003e8\u003c/sub\u003e-50%RDF + 50%poultry manure+ Biochar\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e560.40 ± 0.59a\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e26.03 ± 0.12c\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e371.40 ± 1.07c\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.26 ± 0.01c\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e563.00 ± 0.82ab\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e26.69 ± 0.21c\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e374.23 ± 1.59c\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\"\u003e \u003cp\u003e1.33 ± 0.01c\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"9\"\u003e*The figures represented are the average of three replications. ± S.E is the standard error of the mean. Different superscripts denote the means that differ substantially among treatments. Note- RDF- Recommended dose of fertilizer, FYM- farm yard manure,\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003cp\u003e\u003c/p\u003e \u003cp\u003eBiochar-enhanced treatments also increased available phosphorus. Fifty percent RDF and fifty percent poultry manure and biochar showed the maximum availability of phosphorus (24.93 and 25.13 kg ha\u003csup\u003e− 1\u003c/sup\u003e), whereas control plots showed a significantly lower concentration (6.39 and 6.65 kg ha\u003csup\u003e− 1\u003c/sup\u003e). The same trends were recorded in wheat, where the availability of phosphorus grew even more, under integrated treatments (to 28.52 kg ha\u003csup\u003e− 1\u003c/sup\u003e). This increased level may be due to low phosphorus fixation, increased microbial activity, and accelerated desorption from biochar surfaces. The availability of potassium had a similar trend. In rice production, 50% RDF + 50% poultry manure + biochar recorded the highest K values (365.0 and 360.7 kg ha-1), whereas the control consistently had the lowest values. The highest potassium content was recorded after wheat harvest (50% RDF + 50% FYM + biochar; 386.23 and 387.0 kg ha-1). The rise in K supply is likely due to both direct nutrient addition via manure and uptake in biochar-amended soils.\u003c/p\u003e \u003cp\u003eThere was a significant response of soil organic carbon (SOC) to integrated treatments. SOC varied across treatments and seasons, ranging from 0.39% to 1.52%. The maximum SOC values after rice were found to be under 50 percent RDF + 50 percent poultry manure + biochar (1.20 percent and 1.16 percent), but less than 0.60 percent was observed in control plots. Following wheat harvesting, SOC increased, particularly when 50% RDF + 50% FYM + biochar was applied (1.45% and 1.52%). These increases are due to the direct addition of carbon from biochar and organic manure, as well as reduced carbon mineralization losses. The increase in the cumulative SOC across seasons suggests improved carbon stabilization and soil quality under integrated nutrient management.\u003c/p\u003e \u003cp\u003eGenerally, biochar with organic amendments and low mineral fertilizer consistently enhanced soil nutrient status and carbon content compared with single fertilizers. The synergistic interactions among nitrogen, phosphorus, potassium, and SOC indicated increased nutrient cycling efficiency and greater soil functional resilience in the rice-wheat system.\u003c/p\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e3.3 Impact of Biochar-based amendments on soil biological indicators:\u003c/h2\u003e \u003cp\u003e \u003cstrong\u003eSoil urease activity\u003c/strong\u003e \u003c/p\u003e\u003cp\u003eThe activity of soil urease was evidently stratified with depth, and in all cases, the activity in the surface layer (015 cm) was much higher than that in the subsurface (15 30 cm) in both cropping seasons (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003ea, b). This trend indicates greater accumulation of organic residue and microbial biomass in surface soil. Urease activity was significantly higher with integrated biochar treatments than with the control and individual RDF treatments. The maximum urease activity was observed with \u0026lt; 50% RDF + 50% poultry manure + biochar, yielding 9.46 and 5.83mg urea g\u003csup\u003e− 1\u003c/sup\u003e soil 24 h\u003csup\u003e− 1\u003c/sup\u003e in surface and subsurface soils, respectively. Such values were statistically equivalent to the 50 percent RDF + 25 percent poultry manure + biochar treatment. Vermicompost-incorporated treatments also exhibited high urease activity, whereas control plots consistently had the lowest activity. The significant improvement in poultry manure-biochar mixture implicates synergistic impacts of labile organic nitrogen sources as well as porous biochar matrix, which could enhance the colonization of microbes and the effectiveness of mineralization of nitrogen. The development of urease activity did not differ significantly among treatments in the wheat season, with the highest activity at 50% RDF + 50% FYM + biochar (8.65 and 6.73mg urea g\u003csup\u003e− 1\u003c/sup\u003e soil 24 h\u003csup\u003e− 1\u003c/sup\u003e in surface and subsurface soils). This seasonal change is likely due to slower decomposition of FYM during the colder wheat-growing period, resulting in prolonged nitrogen release. All treatments containing biochar showed a significant improvement over the control across seasons, demonstrating the potential to enhance nitrogen transformation through integrated nutrient management.\u003c/p\u003e \u003cp\u003e\u003c/p\u003e \u003cp\u003e \u003cstrong\u003eSoil dehydrogenase activity\u003c/strong\u003e \u003c/p\u003e\u003cp\u003eThe global microbial oxidative activity indicator (dehydrogenase activity (DHA)) was very responsive to integrating nutrients using biochar (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003ec, d). The highest DHA was observed at 50 percent RDF + 50 percent poultry manure + biochar (14.2 and 10.47 mg TPF g\u003csup\u003e− 1\u003c/sup\u003e soil day\u003csup\u003e− 1\u003c/sup\u003e for surface and subsurface, respectively), and then decreased with poultry manure treatments. Control plots showed significantly low values, indicating that microbial respiration was suppressed under sole mineral fertilization. During the following wheat season, DHA improved significantly, particularly when the percentage of RDF + 50% FYM + biochar was less than 50%, with surface soil activity reaching 27.5 mg TPF g\u003csup\u003e− 1\u003c/sup\u003e soil on day 1. The pronounced accumulation of the increase in wheat indicates cumulative effects of carbon addition and microbial stabilization across crop-planting times. Surface soils consistently had higher DHA than subsurface soils, further supporting the contribution of organic inputs to enhanced microbial metabolism. The stable increase in DHA at biochar manure mixtures suggests the existence of better conditions of microbial habitats, presumably through enhanced SOC, enhanced aeration, and enhanced moisture retention. The findings indicate that biochar can stabilize carbon and promote the active role of microbes in the presence of nutrients.\u003c/p\u003e \u003cp\u003e\u003c/p\u003e \u003cp\u003e \u003cstrong\u003eSoil acid phosphatase activity\u003c/strong\u003e \u003c/p\u003e\u003cp\u003eThere was significant variation in acid phosphatase activity among treatments, and it was consistently higher in surface soils (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003ea, b). The activity varied across the rice crop, with the highest value of 50% RDF + 50% poultry manure + biochar (197.33 and 75.27 µgPNPg\u003csup\u003e− 1\u003c/sup\u003e soil h\u003csup\u003e− 1\u003c/sup\u003e in the surface and subsurface, respectively) observed. Control plots showed the least activity, indicating low phosphorus cycling in the biological component when fertilizer was used alone. During the wheat season, the highest activity of acid phosphatase appeared in RDF + 50% FYM + biochar (152.3 and 72.4 µgPNPg\u003csup\u003e− 1\u003c/sup\u003e soil h\u003csup\u003e− 1\u003c/sup\u003e). The observed increases indicate improved phosphorus mineralization with integrated nutrient management. High phosphatase activity may indicate increased phosphorus demand by microorganisms and enhanced substrate availability in biochar-amended soils. The significant improvement in phosphatase activity during biochar-organic manure treatments indicates increased biological phosphorus turnover and possibly decreased reliance on external P inputs.\u003c/p\u003e \u003cp\u003e\u003c/p\u003e \u003cp\u003e \u003cstrong\u003eSoil alkaline phosphatase activity\u003c/strong\u003e \u003c/p\u003e\u003cp\u003eThe trends in alkaline phosphatase were unsurprising and resembled those of acid phosphatase, except that alkaline phosphatase activity was higher in the topsoils and in biochar-integrated treatments (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003ec, d). The highest activity was observed in 50 percent RDF + 50 percent poultry manure + biochar (181.33 and 74.56 µgPNPg\u003csup\u003e− 1\u003c/sup\u003e soil h\u003csup\u003e− 1\u003c/sup\u003e) during rice, whereas control plots recorded the lowest values. The activity of alkaline phosphatase rose further, especially at a combination of RDF 50 or FYM + biochar (197.4 and 80.4 µgPNPg\u003csup\u003e− 1\u003c/sup\u003e soil h\u003csup\u003e− 1\u003c/sup\u003e). The accretive increase between seasons indicates gradual stimulation of phosphorus-changing microbial communities. The overall uniform improvement in phosphatase activity during biochar-based treatment indicates increased phosphorus mobilization in the system. The overall pattern of enzyme activity indicates that biochar, when used in combination with organic manures, significantly enhances soil biological functioning. The increased urease, dehydrogenase, and phosphatase activities indicate that nitrogen and phosphorus cycling is enhanced, as microbial activity and soil functional resilience increase under integrated nutrient management.\u003c/p\u003e \u003cp\u003e\u003c/p\u003e \u003cp\u003e \u003cb\u003e3.4 Correlation and scatter plot matrix\u003c/b\u003e: Pairwise scatter plots (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003ea, b) indicated that there were close relationships between the physical, chemical, and biological parameters of soil. A negative correlation between bulk density and porosity was observed, indicating that decreased compaction increased pore space. The positive correlations among organic carbon, porosity, and nutrient availability were strong, underscoring the primary importance of organic carbon in structural stabilization and nutrient retention. The positive correlations between pH, EC, and available phosphorus and potassium indicate that slight changes in soil reaction and ionic strength during biochar treatments were associated with increased nutrient solubility, but not with salinity stress.\u003c/p\u003e \u003cp\u003eMoreover, there were strong positive correlations between SOC and biological enzyme activities (urease, dehydrogenase, acid phosphatase, and alkaline phosphatase). Enzyme activities were also positively correlated with the availability of nitrogen and phosphorus. These tendencies indicate that increased carbon inputs and nutrient availability during biochar-based treatments stimulated microbial-mediated nutrient transformations. The intercorrelated patterns of enhanced physical structure, carbon content, nutrient availability, and biological activity in the soil occurred not independently. Nutrient management with biochar as a component of integrated nutrient management thus enhanced the overall quality of soil functions, including structural stabilization and increased nutrient cycling through microbes.\u003c/p\u003e \u003c/div\u003e"},{"header":"4. Discussion","content":"\u003cp\u003eThe primary aim of the current study was to investigate biochar and its effects on the soil physico-chemical and biological properties in the Punjab rice-wheat cropping system. One notable finding was that the bulk density was lowest and the porosity was highest in rice husk biochar plots, in line with the prior observations and reports by other researchers that biochar particle size, surface area, and porosity could have a strong impact on the bulk density of soil (Downie et al., \u003cspan class=\"CitationRef\"\u003e2011\u003c/span\u003e). Combining 50 per cent RDF, poultry manure, and biochar yielded the greatest reduction in bulk density during rice production. The same changes were observed in plots containing poultry manure alone: bulk density decreased and porosity increased in both years. It is also possible that most of the biochar was more porous, thereby increasing the volume of soil pores and subsequently improving porosity and lowering bulk density (Suliman et al., \u003cspan class=\"CitationRef\"\u003e2017\u003c/span\u003e). Such effects are applicable in practice because reduced bulk density enhances water infiltration and retention, as observed by Alghamdi (\u003cspan class=\"CitationRef\"\u003e2018\u003c/span\u003e), who reported high porosity and penetration in plots treated with biochar.\u003c/p\u003e\u003cp\u003eBased on modifications to soil physical characteristics, the continuous use of both FYM and vermicompost also decreased the bulk density of wheat, whereas the use of biochar combined with 50% RDF and 50% FYM significantly increased it. The combined effect of FYM, RDF, and biochar on soil organic matter improved soil porosity and reduced bulk density. These findings are consistent with those of Riaz et al. (\u003cspan class=\"CitationRef\"\u003e2018\u003c/span\u003e) and Choudhary et al. (\u003cspan class=\"CitationRef\"\u003e2019\u003c/span\u003e), which indicate that organic matter content is critical in altering soil structural properties. In terms of soil pH and salinity, biochar had an insignificant effect on changes because of its high CEC and buffering capacity in the initial stage, which regulates pH fluctuations (Suliman et al., \u003cspan class=\"CitationRef\"\u003e2017\u003c/span\u003e). However, when biochar, poultry manure, and synthetic fertilizers are combined, they can reduce soil salinity by increasing soil pH and CEC. This buffering capacity maintains a constant pH conducive to plant growth. FYM + RDF + biochar significantly affected pH in wheat, likely due to increased CEC and organic matter. The basic cations present in poultry manure and the release of organic anions, including malate and citrate, also helped increase pH, consistent with the results of Novak et al. (\u003cspan class=\"CitationRef\"\u003e2016\u003c/span\u003e). Additionally, the changes in chemical properties were likely influenced by pyrolysis-induced alkaline residues on the biochar surface (Novak et al., \u003cspan class=\"CitationRef\"\u003e2021\u003c/span\u003e) and by the presence of Ca, Mg, K, and Na in rice straw. Another indicator of soil solution chemistry, soil electrical conductivity (EC), was great in the first year but was lower in the second year. The trend indicates that nutrient absorption by crops reduced the ion concentration in the soil solution. The enhanced EC during the first year was likely due to nutrient release from the biochar surface, which enabled plant nutrient uptake (Abujabbah et al., 2016; Alkharabsheh et al., \u003cspan class=\"CitationRef\"\u003e2021\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eNitrogen availability, an essential component of crop nutrition, was enhanced when biochar was used in combination with poultry manure and synthetic fertilizers. The porous surface of biochar retained nitrogen from applied fertilizers and manure, thereby increasing nitrogen availability to rice crops. Slow decay of organic matter in poultry manure also increased available N. Biochar co-composted with poultry manure exhibited greater nutrient retention, and wheat plots with 50% RDF + 50% FYM + biochar had high N availability. On the other hand, the control plots indicated low nitrogen concentrations, which could have resulted from immobilization and volatilization. In both years, the combined application of biochar, manure, and fertilizers continued to enhance inorganic N availability, presumably through reduced leaching and increased mineralization, consistent with the findings of Oladele et al. (\u003cspan class=\"CitationRef\"\u003e2019\u003c/span\u003e). The use of biochar also increased phosphorus availability. Its strong CEC and surface interactions enhanced plant P retention and uptake, thereby improving soil fertility (Liu et al., \u003cspan class=\"CitationRef\"\u003e2017\u003c/span\u003e). Mycorrhizal associations were also promoted by biochar, which enhanced P absorption. Increasing soil pH decreased P sorption, consistent with Cao et al. (\u003cspan class=\"CitationRef\"\u003e2020\u003c/span\u003e), who found higher P levels in biochar-treated soils. FYM, in conjunction with biochar and synthetic fertilizer, was important in the release of P as a result of single superphosphate (SSP) because of the formation of organic acids. Sarfaraz et al. (2020), Jing et al. (2017), and Randolph et al. (\u003cspan class=\"CitationRef\"\u003e2017\u003c/span\u003e) confirmed these observations, stating that biochar and organic amendments act synergistically to increase soil P concentrations. The availability of soil potassium (K) was significantly enhanced by the use of rice straw biochar, FYM, and inorganic fertilizers. Biochar has high K content and is water-soluble; therefore, it demonstrated a substantial increase in K levels relative to the control treatments. In pyrolysis, extractable K is released at temperatures above 600°C (Bilias et al., \u003cspan class=\"CitationRef\"\u003e2023\u003c/span\u003e), and plants readily take up this K. FYM provides organic colloids that facilitate K ion exchange. An elevated level of organic matter promotes K mineralization. These results are in line with those of Wang et al. (\u003cspan class=\"CitationRef\"\u003e2018\u003c/span\u003e), Xiu et al. (\u003cspan class=\"CitationRef\"\u003e2023\u003c/span\u003e), and Bilas et al. (2023), who noted that there is a close correlation between organic matter and K dynamics. Organic carbon (SOC) in soils is important for sustaining microbial activity and nutrient storage. Treatments that combined charcoal, manure, and fertilizer produced the highest SOC. Specifically, 50 percent RDF + 50 percent PM + biochar in rice and 50 percent RDF + 50 percent FYM + biochar in wheat showed substantial increases in organic carbon content. Such improvements can be attributed to oxidation of the biochar surface and increased microbial activity during decomposition (Zhang et al., \u003cspan class=\"CitationRef\"\u003e2021\u003c/span\u003e). Biochar also enhanced the bond between organic amendments and nitrogen retention and the absorption of organic carbon (Das et al., \u003cspan class=\"CitationRef\"\u003e2017\u003c/span\u003e), supporting previous field and laboratory experiments (Ali et al., \u003cspan class=\"CitationRef\"\u003e2021\u003c/span\u003e). This higher SOC, in turn, encouraged improved nutrient cycling and aeration (Naeem et al., \u003cspan class=\"CitationRef\"\u003e2018\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eUrease enzyme activities were the highest in treatments that had 50% RDF + 50% PM + biochar in the rice growing. This rise may be due to enrichment of microbial biomass by organic inputs, as supported by Sakin et al. (\u003cspan class=\"CitationRef\"\u003e2021\u003c/span\u003e) and Pokharel et al. (2021). Consistent with Song et al. (\u003cspan class=\"CitationRef\"\u003e2020\u003c/span\u003e), urease activity also indicates microbial decomposition of organic matter. Wheat showed the greatest activity of urease in the plots and only 50% RDF and 50% FYM + biochar, which may be explained by the higher release of nitrogenous compounds by both the fertilizers and root exudates (Du et al., \u003cspan class=\"CitationRef\"\u003e2014\u003c/span\u003e). Enzyme activities are also high in these treatments due to microbial fermentation of the added organic matter. The other important soil biological indicator, which was greatly increased by 50% RDF + 50% FYM+ biochar in wheat and 50% RDF + 50% PM+ biochar in rice was dehydrogenase activity (DHA). This enzyme activity reflects the microbe's overall oxidative processes and is sensitive to organic matter levels. The growth in DHA is consistent with studies by Saha et al. (2021), Sharma et al. (\u003cspan class=\"CitationRef\"\u003e2023\u003c/span\u003e), and Premalatha et al. (\u003cspan class=\"CitationRef\"\u003e2023\u003c/span\u003e), who also reported similar trends in biochar-amended soils. The control and 100% RDF treatments showed the lowest DHA levels, which may be explained by the adverse effects of high salt levels in synthetic fertilisers, which inhibit microbial oxidation capacity (Akumuntu et al., \u003cspan class=\"CitationRef\"\u003e2024\u003c/span\u003e). The decreased enzyme activity in these plots could be attributed to increased soil redox potential and increased nitrate accumulation, which inhibit microbial respiration. Phosphorus mineralization was also treatment sensitive through enzyme phosphatase. The activity of acid phosphatase was also significantly higher than that of alkaline phosphatase, likely due to the acidic soil conditions. RDF 50% + FYM 50% + biochar in wheat produced the highest acid phosphatase activity, which may have been caused by a high level of organic carbon and nitrogen (Reddy et al., 2018). This enzyme, along with organic acids produced by FYM decomposition, further enhanced this activity (Durgude et al., \u003cspan class=\"CitationRef\"\u003e2018\u003c/span\u003e). These high phosphatase enzyme levels in FYM, VC, and PM+ biochar treatments highlight the role of organic matter in the release of microbial enzymes. The increase in fine roots in biochar-amended soils likely facilitated high levels of enzyme activation through nutrient demand and root exudation.\u003c/p\u003e"},{"header":"5. Conclusion","content":"\u003cp\u003eBased on the data presented above, it can be concluded that the effects of biochar on soil parameters differed relative to NPK fertilizer and the control group. The research concluded that 50%RDF and 50% poultry manure with biochar is the most appropriate one that can be used on rice fields. This is superior to others in nutrient retention, gas exchange, and pore-space ventilation under submerged conditions. Additionally, it can directly provide nitrogen to rice-wheat crops. A mixture of rice straw biochar, half farmyard manure (FYM), and half RDF is effective for growing upland wheat. This mixture was effective in improving soil physical properties, reducing bulk density, increasing water-holding capacity, and retaining nutrients. Recent studies indicate an increase in soil physical and chemical properties. However, some gains, such as soil bulk density and water retention, were considerably lower than those observed under the control and NPK fertilizer treatments. Biochar-treated plots also had high enzyme activities in the topsoil. The addition of synthetic manure, organic manure, and biochar, namely 50 percent RDF\u0026thinsp;+\u0026thinsp;50 percent PM\u0026thinsp;+\u0026thinsp;Biochar and 50 percent RDF\u0026thinsp;+\u0026thinsp;50 percent FYM\u0026thinsp;+\u0026thinsp;Biochar, has resulted in positive changes in the measured soil parameters. This demonstrates the potential of biochar to reduce reliance on synthetic fertilisers and improve soil nutrient-use efficiency.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003ch2\u003eConflict of interest:\u003c/h2\u003e \u003cp\u003eThere is no conflict of interest between the authors\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eCompeting Interests:\u003c/strong\u003e \u003cp\u003eThe authors have no relevant financial or nonfinancial interests to disclose.\u003c/p\u003e \u003c/p\u003e\u003cp\u003e \u003ch2\u003eConsent to Publish\u003c/h2\u003e \u003cp\u003e \u003cb\u003eConsent to Publish\u003c/b\u003e: Not applicable.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cb\u003eConsent to Participate\u003c/b\u003e: Not applicable.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eEthics Declaration\u003c/strong\u003e \u003cp\u003eThe study involved only cultivated crops (rice and wheat) grown under field conditions. All plant materials were obtained from authorized and certified sources, and cultivation practices complied with the national and local agricultural guidelines of India. No wild plant species were collected, and no specific permissions or licenses were required for the procurement or use of plant materials in this study.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eFunding:\u003c/h2\u003e \u003cp\u003eThe authors declare that \u003cb\u003eno external funding\u003c/b\u003e was received for the conduct of this study or the preparation of this manuscript.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eAnita Jaswal and Arun Kumar conceived and designed the study. Anita Jaswal and Arshdeep Singh carried out material preparation, field experimentation, and data collection. Data analysis and interpretation were performed by Arun Kumar, Chandra Mohan, Anita Jaswal, and Arshdeep Singh. Arun Kumar and Chandra Mohan provided overall supervision and critical intellectual input. All authors reviewed and approved the final manuscript.\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eThe author gratefully acknowledges the institutional support provided by Lovely Professional University, Punjab, India, and Manipal University Jaipur, India. The manuscript language was reviewed using Grammarly Premium to improve clarity and readability.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eThe datasets generated and/or analyzed in the current study are available from the corresponding author upon reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eAbujabhah IS, Doyle R, Bound SA, Bowman JP. The effect of biochar loading rates on soil fertility, soil biomass, potential nitrification, and soil community metabolic profiles in three different soils. 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Sci Rep. 2019;9:16531. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1038/s41598-019-52978-w\u003c/span\u003e\u003cspan address=\"10.1038/s41598-019-52978-w\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"discover-sustainability","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"disu","sideBox":"Learn more about [Discover Sustainability](https://www.springer.com/43621)","snPcode":"","submissionUrl":"","title":"Discover Sustainability","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Discover Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Sustainable agriculture, enzymatic activities, soil fertility, amendment, biochar","lastPublishedDoi":"10.21203/rs.3.rs-8557311/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8557311/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe key limitation to crop productivity in Punjab is nutrient imbalance and declining soil fertility, with intensive rice–wheat cropping systems and the removal of above-ground biomass after harvest negatively affecting soil health. Although mineral fertilizers have played a crucial role in achieving food self-sufficiency, maintaining long-term productivity requires sustaining adequate levels of soil organic matter to support physical, chemical, and biological soil processes. In this context, the application of amendments derived from agricultural biomass, such as biochar, can be considered a viable option for enhancing soil fertility and sustainability. The objective of the present study was to evaluate the impact of rice straw biochar combined with organic and inorganic fertilizers on the physico-chemical and biological properties of soil under a rice–wheat cropping system. The field experiment was conducted at the Department of Agronomy, Crop Research Centre, Lovely Professional University, Phagwara, using a randomized block design with nine treatments and three replications. Rice straw biochar was applied at recommended rates alongside fertilizers and organic amendments. The results indicated that biochar-amended plots exhibited higher soil pH, porosity, bulk density, nutrient availability, soil enzymatic activities, and organic carbon content than the control and sole RDF treatments. Biochar application reduced soil bulk density, increased organic carbon content, regulated soil pH, and enhanced enzymatic activity, indicating improved soil biological functioning. The integration of rice straw biochar with organic and inorganic nutrient sources—particularly 50% RDF combined with poultry manure or farmyard manure and biochar—has emerged as a promising, farmer-viable approach for improving soil quality and achieving sustainable productivity in the rice–wheat cropping system. The significance of the proposed study is placed in the context of sustainable development, as it aims to meet SDG-2 (Zero Hunger) by enhancing soil fertility and crop yields, SDG-12 (Responsible Consumption and Production) by recycling rice straw into biochar, SDG-13 (Climate Action) by improving the efficiency of soil carbon sequestration, and finally SDG-15 (Life on Land) by improving the health of the soil. The proposed biochar-based approach offers a sustainable alternative to fertilizer-intensive practices prevalent in the Indo-Gangetic Plains.\u003c/p\u003e","manuscriptTitle":"Biochar-Based Integrated Nutrient Management Improves Soil Quality and Biological Functioning in a Rice–Wheat Cropping System","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-02-23 08:57:10","doi":"10.21203/rs.3.rs-8557311/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-03-18T12:06:28+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-03-13T06:00:03+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-03-12T16:23:41+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"128450877473267364115799317558518720599","date":"2026-02-20T13:47:08+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"315446728136220660341118269103389844225","date":"2026-02-19T08:02:16+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"219522105741210784950480365570252380512","date":"2026-02-19T02:46:32+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-02-18T17:35:26+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-02-18T10:41:03+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-02-18T06:20:59+00:00","index":"","fulltext":""},{"type":"submitted","content":"Discover Sustainability","date":"2026-02-18T06:09:06+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"discover-sustainability","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"disu","sideBox":"Learn more about [Discover Sustainability](https://www.springer.com/43621)","snPcode":"","submissionUrl":"","title":"Discover Sustainability","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Discover Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"d2e58572-ca8b-4616-abe4-8bc1f0d70f3f","owner":[],"postedDate":"February 23rd, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-04-23T08:10:50+00:00","versionOfRecord":[],"versionCreatedAt":"2026-02-23 08:57:10","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8557311","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8557311","identity":"rs-8557311","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}