Reducing Farm‑Runoff with Smart Fertilizer Use

Fertilizers give crops the nitrogen they need, but when too much leaches into rivers it harms fish and plants. Scientists need to know how much nitrogen leaves fields each year to plan better solutions. Because real‑world data are scarce, researchers built a computer model that learns from all the field records they could find worldwide. The model looks at similar climates, soils and farming practices to guess how much nitrogen would run off from any given crop. With this tool, they created detailed maps showing the expected nitrogen loss for rice, wheat and maize farms everywhere. In 2020, these crops released about 2. 33 trillion grams of nitrogen into water bodies worldwide.

Future climate models predict a small rise in runoff by 2060 and a larger increase by 2100, but the changes are not huge. The team also tested nearly a hundred ways to change fertilizer timing, amounts and types for each crop. They discovered that the best trick is different in every region – a one‑size‑fits‑all plan does not work. By carefully adjusting how and when nitrogen is applied, farmers could cut runoff by more than one‑fifth. This would save roughly 0. 52 trillion grams of nitrogen each year without cutting total fertilizer use. Importantly, the savings would stay in place even as temperatures climb and rainfall patterns shift. The study offers a practical, climate‑smart method that can be used anywhere to keep water cleaner while keeping yields high.

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