As winter approaches, it’s the best time to determine if crops hit by the 2012 drought left any residual nitrogen (N) or other nutrients in your soil profile.

Residual soil nitrates can be higher after a drought where N was applied. This happens because of decreased downward soil water movement and reduced N uptake by drought-stressed plants. The effect of the 2012 drought on phosphorus (P) and potassium (K) is largely dependent on how the crop was managed. While less P and K may be removed at harvest as an outcome of lower grain yields, P and K removal could be greater than planned if the plant was cut for silage instead of harvested for grain.

With regard to N, farmers should be incorporating the 4R Nutrient Stewardship program and consider the following:
– How much applied N is left in the soil profile?
– How much of that N will remain in the soil until next spring?
– What can be done to prevent its loss?
– What adjustments need to be made to fertilizer rates for the next crop?

Sampling is key, especially after a drought, because drought reduces crop uptake and removal of nutrients. Whether or not residual N will be available for next season’s crop depends greatly on the precipitation that occurs after harvest. In the Midwest, nitrate losses are associated with wet periods during fall, winter and early spring when roots are not actively taking up N. Soil testing and plant analysis remain the best tools for quantifying the drought’s impact and adjusting nutrient management.

More information about the 4R Nutrient Stewardship Program is available here.