A new study by researchers at the Indian Institute of Technology Gandhinagar (IITGN) and the Helmholtz Centre for Environmental Research (UFZ) suggests that India could cut agricultural pollution, reduce greenhouse-gas emissions and save vast quantities of groundwater by reorganising cereal production around a single target: nitrogen surplus. The modelling study, published in Nature Communications, finds that reducing the amount of fertiliser nitrogen left unused by crops could deliver wider environmental benefits than policies focused on water consumption alone, while maintaining national calorie production and the economic returns of the cereal sector.
Nitrogen surplus is the portion of nitrogen applied to farmland that is not absorbed by crops. In India, much of this unused nitrogen originates from synthetic fertilisers, but it can also enter fields through manure, biological nitrogen fixation and atmospheric deposition. Once it is no longer retained in harvested grain, nitrogen may leach into groundwater as nitrate, run off into rivers, or escape into the atmosphere as ammonia, nitrous oxide and other reactive compounds. Nitrous oxide is a particularly powerful greenhouse gas, while excess nitrate threatens drinking-water quality and contributes to the degradation of aquatic ecosystems. Because nitrogen persists across soil, water and atmospheric systems, the researchers argue that it should become a central indicator of agricultural sustainability.
The study was led by Dr Shekhar Sharan Goyal of UFZ, with Professor Udit Bhatia of IITGN and Dr Rohini Kumar of UFZ serving as co-corresponding researchers. Their optimisation model examined cereal production across 664 Indian districts, reallocating existing farmland among six crops: rice, wheat, maize, sorghum, pearl millet and finger millet. The model was constrained so that no state would produce fewer calories than it did in 2017, the cereal sector would retain its 2017 net returns, and crops could expand only in regions with documented cultivation histories. These conditions were designed to prevent the results from becoming a purely theoretical national reshuffle disconnected from local farming experience.
Under the nitrogen-focused scenario, rice cultivation declined by 8.8 percent and wheat cultivation by 12.1 percent. The land released by these reductions was redirected primarily toward maize and three traditional millets: sorghum, pearl millet and finger millet. Together, these crops increased their share of cereal cropland from roughly one-quarter to almost one-third. The model did not recommend eliminating rice or wheat, nor did it assume that diets or established agricultural systems could be transformed overnight. Instead, it identified marginal shifts in crop area that could reduce environmental pressure while preserving existing food-energy production and recognising the crops already grown in particular districts.
The most striking result was that water conservation emerged as a consequence of nitrogen management rather than its primary objective. When the model was optimised to minimise nitrogen surplus, agricultural water use fell by 18.6 percent, equivalent to approximately 86.8 billion cubic metres annually. By comparison, a strategy designed specifically to reduce water use generated a much smaller nitrogen benefit. According to the researchers, the water savings produced by the nitrogen-led strategy were about 4.6 times greater than the nitrogen savings achieved by a water-focused strategy. The difference reflects the overlapping pressures associated with rice cultivation, which generally requires substantial irrigation, receives high fertiliser inputs and produces methane under flooded conditions.
The environmental gains extended beyond water. The proposed crop restructuring reduced agricultural greenhouse-gas emissions by 8.7 percent, combining lower methane emissions from paddy fields with reductions in nitrous oxide associated with fertiliser use. Fertiliser pollution declined by 13.4 percent, nitrogen leaching by 11.3 percent and reactive nitrogen emissions by 13.9 percent at the national level. The researchers estimate that the avoided environmental damage would be worth approximately $1.19 billion, or around ₹10,000 crore, each year. These figures place nitrogen management at the intersection of several policy priorities, including groundwater protection, climate mitigation, air-quality improvement and the long-term security of food production.
The model also revealed that changing the crops grown in different regions would require changes in India’s interstate trade network. As rice and wheat shipments from major producing states declined, flows of maize, sorghum and the different millets increased, allowing importing states to maintain their calorie supplies. The restructuring created potential trade connections between states that currently exchange little or no coarse cereal. This finding could help policymakers plan procurement, storage facilities, transport systems and support prices for crops that have historically received less market infrastructure than rice and wheat. Without those systems, however, farmers may have little financial incentive to change what they grow, regardless of the environmental advantages.
The researchers emphasise that the proposal is not a blanket call to replace rice and wheat with millets. Crop choices remain dependent on soil, climate, irrigation access, consumer demand and guaranteed markets. Rice displaced millets in many regions partly because public procurement and price-support policies rewarded rice production, while established supply chains made the crop commercially reliable. A nitrogen-led transition would therefore require the same level of institutional support for alternative cereals, including local procurement, adequate storage, reliable transport and markets that protect farm incomes. “The point is about growing the right crop in the right place,” Professor Bhatia said, adding that coarse cereals must be paired with the support farmers need to adopt them without losing income.
The study has several important limitations. Its optimisation focuses on cereal-to-cereal substitutions and does not include pulses and legumes, which could contribute further to nitrogen management through biological fixation and dietary diversification. The calorie constraint measures food energy rather than complete nutritional quality, even though millets can provide greater amounts of iron, calcium and other micronutrients than rice. The economic analysis uses state-level benchmarks for net returns, while actual profitability varies among farms. Adoption would also depend on consumer willingness to eat more coarse cereals. Nevertheless, the authors argue that India’s exceptional climatic diversity and large agricultural geography give it an unusual opportunity to redistribute crop production without compromising food security.
The findings arrive as India confronts falling groundwater levels in Punjab and Haryana, rising fertiliser subsidy costs and the need to reduce agricultural emissions before the country’s 2070 net-zero target. The researchers describe the results as a modelling-based guide rather than an implementation plan, but they argue that the analysis changes the order in which agricultural trade-offs should be considered. Optimising for water alone may leave fertiliser pollution untouched, whereas reducing nitrogen surplus can simultaneously lower water demand, greenhouse-gas emissions and contamination of soil and water. For a country seeking to produce enough food under intensifying environmental pressure, nitrogen may be the overlooked lever capable of moving several sustainability goals at once.
Subject of Research: Nitrogen-based restructuring of India’s cereal cultivation and its environmental, economic and interstate trade implications
Article Title: Quantifying environmental co-benefits of nitrogen-based crop restructuring and its implications on India’s interstate trade network
News Publication Date: 4-Aug-2026
Web References: Indian Institute of Technology Gandhinagar: https://iitgn.ac.in/; Helmholtz Centre for Environmental Research: https://www.ufz.de/; Nature Communications article: https://www.nature.com/articles/s41467-026-75905-w; Shree Anna mission: https://www.pib.gov.in/PressReleasePage.aspx?PRID=1908322®=48&lang=2
References: Goyal, S. S., Bhatia, U. and Kumar, R., “Quantifying environmental co-benefits of nitrogen-based crop restructuring and its implications on India’s interstate trade network,” Nature Communications, DOI: 10.1038/s41467-026-75905-w
Image Credits: Indian Institute of Technology Gandhinagar
Keywords: nitrogen surplus, Indian agriculture, cereal crops, rice, wheat, millets, groundwater, fertiliser pollution, greenhouse-gas emissions, nitrogen management, sustainable agriculture, climate change, interstate trade, food security
