With the warm sunny days we have had the last few weeks, I have seen Clinton County farmers out and about pulling big white anhydrous ammonia tanks and making applications. With the heavy rains we have been experiencing, it is important to consider the amount of potential nitrogen loss that can occur because of saturated fields. Nitrogen loss increases under excessive rainfall in three ways, runoff, leaching, and denitrification.
Soil erosion that occurs because of heavy rainfall in fields with no cover or residues can take a lot of N along with it. This is especially true of N that hasn’t been incorporated.
The nitrate form of nitrogen can leach downward through the soil profile, this is more prevalent in course textured soils than in fine textured soils. In addition to the amount of rain, leaching potential of N also is dependent on the type of fertilizer used. Nitrate in the form of UAN (urea and ammonium nitrate in water) increases the possibility for leaching because 25% of UAN is in nitrate form on day one of application. In contrast, anhydrous ammonia gets converted to leachable nitrate in about three to eight weeks.
Soil saturated in water can release N into the atmosphere via the denitrification process. Denitrification means that nitrate is being converted into a gas. The amount of time that the soil is waterlogged along with the temperature can determine the amount of N loss through denitrification, warmer temperatures accelerate this process.
In the case that you lost N due to any of the mechanisms mentioned above, it is important to supplement N to growing crops to avoid loss in yield. It is important that you take steps to understand how much N you may have lost, do so by visiting Concerns for N Loss in Corn from Recent Storms | Agronomic Crops Network (osu.edu) to estimate N loss.
*information used from the C.O.R.N Newsletter
