A Precision N Management Approach to Minimize Impacts.

Nitrogen fertilizer is a crucial input for crop production but contributes to agriculture’s environmental footprint via CO₂ emissions, N₂O emissions, and eutrophication of coastal waters. The low-cost way to minimize this impact is to eliminate over-application of N. This is more difficult than it sounds. Weather interacting with terrain has a huge influence on N loss, N mineralization, and crop yield potential (therefore N demand). Optimal nitrogen fertilizer rate varies widely from year to year, field to field, and place to place within a field. Precision N management technologies are the only way to address within-field variability, and some may help to address year-to-year or field-to-field variability as well. Examples of precision N management will be presented, including canopy sensors, remote sensing, N credit zones, soil productivity zones, and grid soil nitrate sampling. We will attempt to quantify the effect of these approaches on agriculture's footprint on the landscape.