Dynamic Soil Nitrogen Fertilization Optimizes Nitrogen Management

Aug 03, 2026

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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Video: From Students to Solutions | On The Brink: Season 2, Episode 14

Ask Canada’s most decorated soybean breeder his favourite part of the job and he doesn’t name a single variety. He names the students.

Istvan Rajcan is a professor of soybean breeding and genetics in the Department of Plant Agriculture at the University of Guelph, where he has run the soybean breeding program for 28 and a half years. In that time he has developed 87 soybean cultivars, published 140 refereed papers and trained 51 graduate students. In 2025 he received the Public Sector Impact Award from the National Association for Plant Breeding.

He is also worried. In this episode he says Canada is at a crossroads, pointing to recent government cuts to plant breeding programs and to the facilities that support them. His prescription is structural. "Plant breeding funding formula has to be a long-term one," he says.

The formula he is defending is the public-private matching arrangement his program runs on. Private seed companies fund the work, provincial or federal money matches it, and the combined pool stretches each dollar further than either source could alone. At the National Association for Plant Breeding annual meeting in June, he says American public breeders were often surprised at how well that collaboration works in Canada.

He also describes how the people entering plant breeding have changed. His early graduate students came mostly from farms. More recently they include, in his words, "city kids who just became excited about genetics."

Topics covered:

Why public-private plant breeding funding in Canada needs a long-term

commitment rather than a larger one

How matching private seed company investment with provincial and federal

dollars multiplies research capacity

How the graduate student pipeline into plant breeding has shifted from

farm kids to city kids