Bio-fertilisers

Imagine hiring a team of tireless, microscopic workers to live in the soil around a plant's roots and continuously convert nutrients already present in the air and earth into a form the plant can actually absorb, rather than trucking in a sack of processed nutrient from a factory. That is essentially what a bio-fertiliser does.

Unlike urea or DAP, which are chemically manufactured, bio-fertilisers are formulations of living microorganisms, bacteria, fungi or algae, that are applied to seeds, soil or roots and then work biologically. Some, like Rhizobium, live in the root nodules of legumes and convert atmospheric nitrogen into a plant-usable form. Others, phosphate-solubilising bacteria among them, unlock phosphorus that is already present in the soil but chemically locked up and unavailable to plants.

Their appeal is straightforward: bio-fertilisers add essentially no cost to India's chemical fertiliser subsidy bill, do not contribute to the soil degradation and groundwater pollution associated with decades of heavy chemical fertiliser use, and are cheap enough for smallholder farmers to adopt without significant new investment.

The catch is equally straightforward. Bio-fertilisers work more slowly and less predictably than chemical fertilisers, are sensitive to storage conditions and soil pH, and cannot fully replace chemical inputs on their own for high-yield, intensive cropping, which is why they are usually promoted as a complement to reduce chemical fertiliser use, under schemes like PM PRANAM, rather than a wholesale substitute.

Whenever a government push toward organic or natural farming is discussed alongside falling chemical fertiliser subsidy targets, bio-fertilisers are typically one of the quiet technical tools policymakers are counting on to make that transition less painful for yields.