As fall fertilizer application season approaches, soil temperature remains an important consideration for nitrogen management. University of Illinois recommendations emphasize waiting until 4-inch bare soil temperatures are consistently below 50°F and trending downward before beginning fall anhydrous ammonia applications.

Warmer soil temperatures can accelerate the conversion of ammonium to nitrate, increasing the potential for nitrogen loss under certain conditions. While nitrification inhibitors can help slow this process, soil temperatures and weather conditions remain important factors in determining application timing.

IFCA's website features a daily updated map, courtesy of the Illinois State Water Survey, displaying the previous day's maximum 4-inch bare soil temperatures across Illinois. This resource allows members to monitor soil temperature trends as the fall application season progresses.

Members are encouraged to use this information, along with local field conditions and weather forecasts, when evaluating fall nitrogen application timing.