Increasing nitrogen use efficiency (NUE) in agricultural production mitigates climate change, limits water pollution and reduces fertilizer subsidy costs. Nevertheless, strategies for increasing NUE without jeopardizing food security are uncertain in globally important cropping systems. Here we analyse a novel dataset of more than 31,000 farmer fields spanning the Terai of Nepal, Bangladesh’s floodplains and four major rice-producing regions of India. Results indicate that 55% of rice farmers overuse nitrogen fertilizer, and hence the region could save 18 kg of nitrogen per hectare without compromising rice yield. Disincentivizing this excess nitrogen application presents the most impactful pathway for increasing NUE. Addressing yield constraints unrelated to crop nutrition can also improve NUE, most promisingly through earlier transplanting and improving water management, and this secondary pathway was overlooked in the IPCC’s 2022 report on climate change mitigation. Combining nitrogen input reduction with changes to agronomic management could increase rice production in South Asia by 8% while reducing environmental pollution from nitrogen fertilizer, measured as nitrogen surplus, by 36%. Even so, opportunities to improve NUE vary within South Asia, which necessitates sub-regional strategies for sustainable nitrogen management.

Yield gap analysis is used to characterize the untapped production potential of cropping systems. With emerging large-n agronomic datasets and data science methods, pathways for narrowing yield gaps can be identified that provide actionable insights into where and how cropping systems can be sustainably intensified. Here we characterize the contributing factors to rice yield gaps across seven Indian states, with a case study region used to assess the power of intervention targeting. Primary yield constraints in the case study region were nitrogen and irrigation, but scenario analysis suggests modest average yield gains with universal adoption of higher nitrogen rates. When nitrogen limited fields are targeted for practice change (47% of the sample), yield gains are predicted to double. When nitrogen and irrigation co-limitations are targeted (20% of the sample), yield gains more than tripled. Results suggest that analytics-led strategies for crop intensification can generate transformative advances in productivity, profitability, and environmental outcomes.

A field study was framed in rice crop under conservation agriculture (CA) based rice-wheat system at experimental farm of Borlaug Institute for South Asia (BISA)-CIMMYT, Ladhowal, Punjab, India during kharif 2019. In the present study, nine treatments were imposed out of which four are CA-based treatments (ZT-N0, ZT-N50, ZT-N75 and ZT-N100), four are CA coupled with subsurface drip fertigation (CA+) based treatments (SSD-N0,SSD-N50, SSD-N75 and SSD-N100) and puddled transplanted rice (PTR) treatment as farmer's practice. The findings of the study showed that PTR treatment out yielded in terms of yield attributing characters and biological yield than other treatments. CA+ treatment (SSD-N100) resulted higher biological yield (2.8%) than CA-based treatments (ZT-N100). SSD-N100 dominated ZT-N100 and PTR treatment in terms of plant N content (both grain and straw), total N uptake and N harvest index. PTR treatment resulted 22-33% higher ANUE than ZT-N100 and SSD-N100 treatments.

Rice provides a foundation for global food security with emerging evidence suggesting that meeting future production demands will require increasing irrigation use in regions such as South Asia and Sub-Saharan Africa where untapped yield potential is high. Consequently, increasing water use in rice may be an unforeseen driver of higher global methane emissions. Here we use Eastern India as an exemplar region to estimate yield and greenhouse gas (GHG) implications of irrigation-led intensification with a model-based data assimilation and scenario approach. Results suggest that if intensification (ca. 2 t ha^-1) is achieved with continuous flood irrigation, current baseline emissions (4.1 t CO₂-eq ha^-1) are anticipated to double (8.8 t CO₂-eq ha^-1) with more moderate increases predicted with precision irrigation practices such as alternate wetting and drying (7.0 t CO₂-eq ha^-1). Robust strategies for achieving effective water management are needed to avoid the most damaging climate impacts of rice intensification.