For decades, conventional Indian agriculture has relied on synthetic fertilisers to boost crop yields. Urea, in particular, has become a staple, heavily subsidised by the government to keep food production steady. But this dependence has come at a cost—soaring input expenses, soil degradation, and alarming levels of water pollution.
With erratic monsoons and climate change intensifying pressure on agriculture, there emerges an alternative to fertilisers: nitrogen-fixing crops, a practice that nourishes the soil in the process of agriculture and nothing more.
The science behind nitrogen fixation
Nitrogen is essential for plant growth, but most crops can’t access it directly from the atmosphere–even though nitrogen makes up 78% of the atmosphere! Instead, plants rely on nitrogen compounds in the soil, often replenished by fertilisers. This is where nitrogen-fixing plants, such as legumes, come in. They have a natural advantage—they form symbiotic relationships with certain soil bacteria (Rhizobia) that convert atmospheric nitrogen (N2), which is in a gaseous form, into ammonia, which is a usable form for the plants. This biological process reduces the need for synthetic fertilisers, making farming more self-sustaining. In theory, it’s a perfect fix—but whether it can hold up in large-scale Indian agriculture, is the complex question that is still being explored.
One of the key challenges in relying on biological nitrogen fixation (BNF) is soil health. The effectiveness of Rhizobia actually depends on soil conditions, including pH, organic matter, and microbial diversity. Afterall, the bacteria fosters a symbiotic relationship–it needs the right nourishment, in exchange for converting atmospheric nitrogen. Degraded soil due to overuse of chemical fertiliszers and intensive farming practices can limit the efficiency of nitrogen-fixing bacteria. Additionally, while legumes contribute to soil fertility, they cannot replace the high nitrogen demands of staple crops like wheat and rice, which dominate Indian agriculture.
Nitrogen fixing process (Credit: Wikimedia Commons)Also read: Humus 101: Why this organic matter is crucial
Another consideration is economic viability. Synthetic fertiliszers offer immediate and predictable results, making them attractive to farmers under pressure to maximisze yields. Transitioning to nitrogen-fixing crops or integrating Zero Budget Natural Farming (ZBNF)–a process of working with nature and without chemicals–requires time, knowledge, and investment. Encouraging sustainable nitrogen management would need policy support, farmer education, and incentives for adopting biofertilisers. But, addressing these challenges could help Indian agriculture move toward more sustainable nitrogen use while maintaining productivity.
Also read: Against the grain: Corporate to sustainable farming
Boon, but not a silver bullet
Across India, nitrogen-fixing crops like pigeon pea (tur), chickpea (chana), and groundnut are already integral to traditional farming. Intercropping these with staple cereals like rice and wheat has been an age-old practice, and farmers have long realised that they improve soil fertility. Yet, large-scale adoption remains limited, especially in high-yield commercial farming. There are a few reasons for this, a significant one being: unlike nitrogen-heavy urea, biological nitrogen fixation works gradually and depends on soil health, microbial activity, and crop cycles. For small and marginal farmers, the lower input costs are a major benefit, but questions remain about whether these crops can fully replace chemical fertilisers in an economy driven by yield maximisation.
Also read: Sikkim shows how to farm without chemicals
Then, there is the fact that government policy continues to favor chemical fertilisers, with urea subsidies exceeding ₹1.31 lakh crore in 2023. This not only distorts farm economics but also disincentivises a shift towards regenerative practices. In fact, if you look closely enough, you’ll see that fertilisers are at the centre of Indian agriculture–even seed markets and agribusinesses prioritise high-yield hybrid varieties that depend on synthetic inputs. So, without policy shifts—such as incentives for intercropping or support for microbial biofertilisers—nitrogen-fixing crops will remain a secondary solution rather than a mainstream alternative for farmers.
While nitrogen-fixing crops alone may not meet India’s food demand, integrating them into existing farming systems could reduce dependency and over reliance on synthetic fertilisers. A hybrid approach—combining legumes, crop rotation, organic mixes, and judicious fertiliser use—could make Indian agriculture both more sustainable and resilient to deteriorating soil health. There have been a few attempts, too. The Biotechnological and Biological Sciences Research Council, UK (BBSRC), Department of Biotechnology, India (DBT), and Natural Environment Research Council (NERC UK) agreed to fund virtual joint centers (VJCs) to investigate the ways of managing agricultural nitrogen, and improving crop production while reducing energy inputs. One of the four centers is IUNFC (India-UK Nitrogen Fixation Center)–which focuses specifically on pigeon pea rhizobial nitrogen fixation through various creative processes, like identifying superior strains of pigeon pea and matching them with effective nitrogen-fixing rhizobia to enhance crop production and developing engineered rhizobia.
But for this movement to really be meaningful, government policies, market structures, and farmer incentives must ultimately align with long-term soil health rather than short-term yield gains.
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