What to know about climate and nitrogen fertilizer management

Climate plays a huge role in the fate of applied nitrogen fertilizer. The two primary loss processes of nitrogen in the soil are both water-based: leaching, when water percolates through the soil; and enitrification, when the soil is saturated.

The conversion of nitrogen to nitrate, the form necessary for loss to happen, is a bacterial process dependent on temperature and moisture. With increasing temperature comes faster rates of nitrification. Microbes respond to temperature. Biological activity slows greatly when the temperature gets below 50 F. This is also why fall nitrogen application is not recommended when daily high soil temperatures at a 6-inch depth are greater than 50 degrees. Similarly, the process of denitrification, which converts nitrate into inert nitrogen gas, becomes significantly more important as soils warm during the growing season.

Extra water on the landscape is going to impact the fate of both naturally occurring (mineralized) nitrogen in the soil and applied nitrogen fertilizer. When precipitation falls — in relation to crop growth and development — is also important.

During the early growing season, there is often more moisture in the soil than the newly-seeded crop can use. This means more water is likely to leave the field through drainage than