Mitigating and Adapting Corn N Management to Climate Change Using Models and High-Resolution Climate Data.

Nitrous oxide accounts for the great majority of agricultural greenhouse gas losses (377 M tons CO₂e), and N losses to the Gulf of Mexico and Chesapeake Bay have not abated in the past decade despite significant efforts.  Much of these concerns relate to high N use in crop production, especially corn.  Climate change is resulting in higher growing season precipitation in the Midwest and Northeast USA, especially through more extreme rainfall in the spring and summer.  High precipitation variability increases the uncertainty in predicting N fertilizer needs for corn production as high short-term N losses may occur through leaching and denitrification from spring and summer rainfall.  Conversely, little losses occur in dryer growing seasons.  This uncertainty results in the general practice of using high “insurance fertilizer” applications which results in over-fertilization during normal and dry years. In extremely wet years, N rates actually need to be adjusted upward.  The current constraint, however, is the limited ability to estimate N fertilizer needs for corn based on weather conditions.  Adaptive nitrogen management for corn production accounts for the effects of weather as well as localized conditions (soil variability, soil management practices, organic matter applications, crop management, etc.) to provide more precise N fertilizer recommendations.  Weather and soil-mediated changes in early season soil N can be estimated by well-calibrated models that simulate soil and crop processes. Model output can then be used to adjust in-season N rates for corn resulting in more precise N management. We developed the Web-based Adapt-N tool, which utilizes newly-developed high resolution climate data to provide farm- or field-specific in-season N recommendations for corn. Adapt-N allows for more precise N management and also improved response to the effects of climate change.