Nitrogen is arguably the most important crop nutrient, and yet it is so incredibly fickle. Leaching and denitrification can leave a well-intended application busted. How can farmers maximize the efficiency of this expensive input?

Eric Scherder, field scientist with Dow AgroSciences, recently shared some of his thoughts on the matter. In particular, he says a few factors can help farmers minimize N losses.

First, timing matters. In general, apply as close as possible to when the crop needs it most, according to Scherder. Also note that corn uses a significant amount of N between V5 and V8. Preserving N with tools such as a nitrogen stabilizer can help preserve available nutrients, he says.

“We can’t limit the nitrogen corn needs at the front end and expect to have maximum yields come harvest,” he says.

Also, farmers should strive to know how weather and soil type can affect available N, Scherder says. For example, spring rains move N lower into soil profiles, sometimes out of the reach of corn roots. And N behaves differently in different soil types, he says.

“For example, in a silt loam or sandy silt loam, nitrate movement down lower into the soil is the key loss mechanism,” he says. “In heavier soils such as clay and clay loams, downward movement is less, yet denitrification is key.”

Need a reliable N rate calculator? Several online tools are available, including this interactive regional guide provided by Iowa State University. (States included are Iowa, Illinois, Indiana, Michigan, Minnesota, Ohio and Wisconsin.)

Want to know if nitrogen stabilizers, optical sensor technology, models for aiding nutrient applications and other high-tech tools are worth it? Farmers will soon have access to reviews of these types of tools with the newly launched NutrientStar program from the Environmental Defense Fund.

EDF has deployed an independent science review panel to test products such as NutriSphere N from Verdesian, Instinct II and N Serve from Dow AgroSciences, ESN from Agrium and Agrotain from Koch Agronomic Services. Decision support tools will also be put to the test, including Farmer’s Edge, FieldView from Climate Corp, 360 Y-Drop from 360 Yield Center, Encirca from Pioneer, NextField from Cargill and Adapt-N from Agronomic Technology Corp. Hardware to be tested includes OptRx and Greenseeker. Much of the testing is already underway.

“NutrientStar is the first-ever review program to provide farmers, their advisers and agricultural supply chain companies with reliable data on the performance of these popular tools,” says John McGuire, EDF adviser and precision agriculture expert. “Farmers need certainty that the tools they purchase will work as advertised.”

More information is available at www.nutrientstar.org.