Researchers seek ways to precisely target fertilizer application

Nitrogen is a nutrient required for crops to grow. When soils lack a natural supply, synthetic nitrogen fertilizers provide a quick fix, boosting nitrogen to the levels needed. Since World War II, these fertilizers have played a vital role in increasing grain production.

But synthetic fertilizers have a dark side. Nitrogen that isn’t absorbed in the soil leaches into the water supply. It feeds the growth of algae, which can threaten aquatic life. Synthetic fertilizers emit nitrous oxide, a potent greenhouse gas, into the atmosphere. They’re made from a dwindling resource that’s not renewable: fossil fuels. On top of all that, they sport a high price tag.

WSU soil scientist David Brown seeks ways to use only as much nitrogen fertilizer as needed—and not a drop more. He and his colleagues in WSU’s Climate-Friendly Farming project are developing a technique for wheat farmers called “precision nitrogen management.”

Supported by a $4.6 million grant from the U.S. Department of Agriculture, the researchers determine exactly how much fertilizer is needed on a given site. They start by gathering detailed information about water, soil, and crops. They analyze the landscape, generating maps of soil and crop properties and soil moisture dynamics. Computer modeling simulates crop growth, organic matter decomposition, water movement, and nutrient uptake.

The goal is to optimize nitrogen fertilizer efficiency. By applying it only when and where needed, growers save money—and the environment gets a break.