Adaptive Nutrient Management: A Process for Refining Nitrogen Management.

The amount of nitrogen needed by corn from manure or fertilizer for individual fields in humid environments is extremely difficult to predict due to large annual standard deviations in the availability of nitrogen from all sources: soils, fertilizers and manures. Most nitrogen recommendations are based on the average yield response to nitrogen across many field experiments, or by using the yield goal concept. Both methods provide less than exact recommendations for individual fields but reasonable average recommendations across a state. Reasonable average nitrogen recommendations for a state, however, result in many fields receiving either excess or insufficient nitrogen due to large standard deviations in nitrogen availability across fields. Refining current recommendations for improved accuracy requires field specific information. Adaptive nitrogen management is a process for systematically evaluating nitrogen needs on individual fields. The process works best when farmers collaborate with a farm advisor to evaluate their nitrogen management by using various evaluation methods such as replicated strip trials, active sensors, or soil and plant tissue tests. Learning from the results of the evaluations is most efficient when the results are discussed with other farmers who have used identical evaluation methods. One-on-one discussions about the results of the evaluations between the farmer and their advisor are also effective for learning from the results. Refinements in nitrogen rates from adaptive management programs have recorded net reductions of 28 to 35 kg N/ha with most fields receiving less nitrogen and some fields receiving more nitrogen than recommended.