Nitrogen fertilizer has helped transform modern agriculture, but its success comes with a costly paradox: crops often receive more nitrogen than they can absorb. The excess can escape into waterways as nitrate, enter the atmosphere as nitrous oxide, or remain in soil in forms that are difficult for plants to use. A new study published in npj Sustainable Agriculture presents a dynamic fertilization strategy designed to match nitrogen applications more closely with the changing needs of crops and soils.
The approach, developed by Yekutiel, Gelfand, Baram and colleagues, is based on a simple but powerful principle: fertilizer decisions should be guided by the nitrogen already present in the soil. Instead of applying a predetermined amount at fixed times, farmers would repeatedly assess the soil’s available nitrogen and adjust future applications accordingly. The goal is to replace a calendar-based routine with a feedback system that responds to real field conditions.
Nitrogen in agricultural soil is constantly moving through a complex biological and chemical cycle. Organic matter is decomposed by microorganisms, releasing ammonium that can be converted into nitrate through nitrification. Plants absorb both forms, but nitrate is highly mobile and can be washed below the root zone by rainfall or irrigation. Under oxygen-poor conditions, microbes can also convert nitrate into gaseous compounds, including nitrous oxide, a greenhouse gas far more powerful than carbon dioxide over a century-long timescale.
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