Adaptive Nitrogen Management for Corn Using Adapt-N: Understanding the Processes and Information Needs.

We will discuss and demonstrate the Adapt-N model for adaptive management of nitrogen use on corn.  Nitrogen management for corn in humid regions is generally imprecise and inefficient.  Current approaches for estimating optimum nitrogen fertilizer rates are based on mass balances, average expected economic return based on field experiments, soil N tests, and crop leaf/canopy sensing.  However, N losses occur from dynamic and complex interactions among weather, soil organic matter mineralization and hydrology, crop water and N uptake, and management practices, resulting in variable annual crop N needs in corn production. In other words, optimum N management is dependent on conditions that are localized and dynamic.  Several studies have documented that weather impacts the early season soil N pool and greatly contributes to the variability in economic optimum in-season N rates for maize.  Large spring rainfall events may result is very substantial N losses with high impacts on the environment through nitrate leaching to groundwater and nitrous oxide losses that contribute to the global warming.  Climate data show that extreme weather events have become more common in many parts of the country.  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.