The rice-wheat cropping system (RWCS) is crucial for food security in India, but its sustainability is threatened by declining soil fertility due to imbalanced nutrient application and intensive cropping. This study focuses on optimizing nutrient management within RWCS by exploring the impact of different crop establishment techniques (CETs) and fertilization strategies. CETs, such as the System of Rice Intensification (SRI), modified SRI, and Aerobic Rice System (ARS) for rice, and zero tillage (ZT) and System of Wheat Intensification (SWI) for wheat, offer potential for improved resource use efficiency and environmental sustainability. However, their effects on nutrient uptake and soil health vary. The increasing nutrient demands of the RWCS, coupled with the negative nutrient balance in Indian soils (a deficit of 10 million tonnes), necessitates a comparative assessment of CETs to identify practices that optimize nutrient use efficiency and minimize environmental impact. This study investigates the effect of CETs on nutrient uptake (N, P, K, Zn, Fe), soil microbial parameters, and soil nutrient availability (P, K, Zn) in RWCS across two cropping cycles. The study also incorporates the effects of varying rates of N and P application via chemical fertilizers, Zn fertilization, and microbial inoculation using N-fixing and P-solubilizing microorganisms. Chemical fertilizers, while essential, are energy-intensive and environmentally costly. Microbial consortia offer a sustainable alternative by enhancing biological N fixation and P solubilization, addressing concerns about over-reliance on chemical fertilizers and the negative impact of excessive N use. The inclusion of Zn fertilization is justified by the widespread Zn deficiency in Indian soils and its impact on both crop yield and human nutrition. Therefore, understanding how CETs and varied fertilization strategies affect nutrient dynamics within RWCS is essential for sustainable agricultural practices.

Existing research highlights the growing importance of optimizing crop establishment techniques (CETs) and management practices in rice and wheat production (1-3). Studies have shown variations in resource utilization, energy requirements (4), and climate change mitigation potential (5) associated with different CETs. These variations have significant implications for farmers' yields and incomes (6), as well as the overall environmental health. The adoption of new CETs and management practices is becoming increasingly critical to address the challenges of natural resource degradation and rising costs associated with chemical and agronomic inputs. The System of Rice Intensification (SRI), developed in Madagascar, has gained traction globally despite varying opinions on its yield superiority (10-13). Modified SRI approaches, focusing on specific SRI components, are sometimes more economically viable (14). SRI is primarily promoted for improved water productivity, even if grain yields remain comparable to conventional puddled transplanted rice (15). The yield advantage of SRI is inconsistent across different regions, with reports showing higher, lower, or similar yields compared to conventional methods (16-18). Aerobic rice systems (ARS) are also gaining popularity due to their water-saving potential (19). In India, substantial areas are dedicated to rainfed upland rice cultivation, facing challenges such as low yields, weed infestation, iron deficiency, and nematode problems (20-24). After rice harvest, wheat cultivation is widespread in India, but the soil conditions and residual effects of the rice crop significantly impact wheat performance. Zero tillage wheat planting is increasingly adopted to address the short turnaround period and rice residue management issues (25, 26). The system of wheat intensification (SWI), adapting SRI principles to wheat, is another gaining attention (27). These different CETs impact soil properties, plant performance, and nutrient and water availability, influencing input recommendations (28, 29). Rice and wheat crops consume a significant portion of India's total fertilizer use (30), underscoring the need for a thorough investigation into the effects of CETs on nutrient dynamics within RWCS (31, 32). The negative soil nutrient balance in India (33) further emphasizes the urgency for improved nutrient management practices within RWCS.

This study employed a split-plot design with six crop establishment techniques (CETs) as main plots and nine nutrient management options as subplots. The experiment was conducted at the ICAR-Indian Agricultural Research Institute, New Delhi. The soil was sandy clay loam with a pH of 7.6 and 5.4 g kg⁻¹ soil organic carbon. Rice ('Pusa Sugandh 5') and wheat ('HD 2967') were the chosen crops. The six CETs included: 1) Puddled transplanted rice (PTR) followed by conventional drill-sown wheat (CDW); 2) System of Rice Intensification (SRI) followed by System of Wheat Intensification (SWI); and 3) Aerobic Rice System (ARS) followed by zero tillage wheat (ZTW). Nine nutrient management options were tested: 1) Control (no fertilizer); 2) Recommended dose of nutrients (RDN: 120 kg N ha⁻¹ and 25.8 kg P ha⁻¹ per crop); 3) RDN + Zn (5 kg Zn ha⁻¹); 4) 75% RDN; 5) 75% RDN + Zn; 6) 75% RDN + microbial consortium 1 (MC1: *Anabaena* sp. + *Providencia* sp.); 7) 75% RDN + MC1 + Zn; 8) 75% RDN + microbial consortium 2 (MC2: *Anabaena–Pseudomonas* biofilm); and 9) 75% RDN + MC2 + Zn. Potassium (K) was applied uniformly at 49.8 kg K ha⁻¹ per crop. The experiment was replicated thrice. Aboveground shoot dry matter was measured after harvesting. Nutrient concentrations (N, P, K, Zn, Fe) in plant samples were determined using standard methods. Soil samples were analyzed for NaHCO₃-extractable P, 1 N ammonium acetate-extractable K, and DTPA-extractable Zn and Fe. Microbial biomass carbon (MBC) and soil chlorophyll were also assessed. Data were analyzed using F-test and LSD (p=0.05) to compare treatment means. Partial factor productivity (PFP) and agronomic use efficiency (AUE) for N and P were calculated. Nutrient balances for P, K, and Zn were determined by considering initial soil nutrient levels, fertilizer application, plant uptake, and final soil nutrient levels.

Biological yield did not differ significantly among the CETs, but nutrient management treatments significantly affected yield. The highest biological yield was observed in ARS-ZTW with RDN + Zn, similar to yields with 75% RDN + MC1 + Zn and 75% RDN + MC2 + Zn. Microbial consortia (MC1 and MC2) increased biological yield by 0.99–1.11 Mg ha⁻¹ and 1.12–1.19 Mg ha⁻¹, respectively. Zinc fertilization increased yield by 0.77–1.06 Mg ha⁻¹ when applied with RDN. Cropping system nitrogen uptake ranged from 129.4 to 290.2 kg ha⁻¹, with ARS-ZTW showing the highest uptake (237.7–245.7 kg ha⁻¹). Microbial inoculation increased N uptake by 28.3–33.0 kg ha⁻¹, and Zn fertilization further increased uptake. Phosphorus uptake was highest in ARS-ZTW with 75% RDN + MC1 or MC2 + Zn. Potassium uptake was similar across CETs and nutrient management treatments due to uniform K application. Zinc uptake was highest with RDN followed by microbial inoculation and Zn fertilization. Iron uptake was highest in PTR-CDW. Soil NaHCO₃-extractable P was higher in treatments with RDN, 75% RDN + MC1/MC2 with or without Zn, while 75% RDN with or without Zn and control showed lower levels. Soil available K decreased consistently across treatments. Soil DTPA-extractable Zn was significantly influenced by Zn fertilization, with the highest increase observed in PTR-CDW with 75% RDN + Zn. Soil chlorophyll and MBC were significantly higher in SRI for rice and ZTW for wheat. Both were positively correlated with biological yield. ARS-ZTW showed higher PFP for N and P compared to other CETs. PTR-CDW exhibited higher AUE. Treatments with MC application had higher PFP than RDN treatments. For phosphorus, 36.9–40.8% of total available P was taken up by plants, 7.6–8.7% contributed to soil available P, and the remaining was not extracted by NaHCO₃. For potassium, both calculated and actual balances were negative. For zinc, only 11.6–18.5% of total available Zn was taken up by plants, with the majority contributing to increased soil DTPA-extractable Zn.

The findings demonstrate the significant impact of CETs, microbial inoculation, Zn fertilization, and N and P application rates on nutrient uptake in RWCS. The rate of N and P application exerted the most significant influence, while the effect of CETs was minimal. The superior performance of ARS-ZTW with microbial inoculation highlights the potential of this combination for efficient nutrient use. Microbial inoculation significantly enhanced N and P uptake, potentially through biological nitrogen fixation and improved P solubilization and mobilization. This is supported by increased soil chlorophyll and MBC. The positive effect of Zn fertilization on soil available Zn and N uptake, along with increased cropping system yield and Zn uptake, is also significant. The observed variations in soil available P, K, and Zn across different treatments are likely attributable to plant uptake, microbial activity, and fertilizer application rates. The results highlight the importance of integrating sustainable nutrient management practices, such as microbial inoculation and optimized fertilizer application, with suitable CETs to enhance nutrient use efficiency and improve soil health in RWCS.

This study demonstrates that combining the aerobic rice system with zero tillage wheat (ARS-ZTW), along with microbial inoculation and balanced nutrient application, significantly enhances nutrient uptake and improves soil nutrient status in the rice-wheat cropping system. The findings highlight the potential of integrating sustainable practices to enhance crop productivity and soil health while minimizing reliance on chemical inputs. Further research could explore the long-term impacts of these integrated strategies and investigate the optimal combinations of microbial inoculants and nutrient management practices for different soil types and climatic conditions.

This study was conducted at a single location, limiting the generalizability of the findings to other geographical areas and soil types. The duration of the study was limited to two cropping cycles, which may not fully capture the long-term effects of the treatments on soil health. Further research is needed to investigate the interactions between different management practices under varying environmental conditions and to evaluate the economic viability of these practices.