Developing a Nitrogen Loss Decision Support Tool for Illinois.

Nitrogen pollution is a primary concern in Midwestern US crop production systems. Nitrogen losses (leaching, denitrification, and/or volatilization) are driven by number of interacting factors including N management practices, climate, soil type, and crop growth, as well as important residual factors such as crop management history and climate trends in previous seasons. Although the complexity of soil N transformations makes it difficult to predict losses, an important question often facing growers is how much N remains in the soil and available to the crop following periods of wet weather. This project was initiated to provide in-season estimates of soil N availability and losses that can be used to make informed N management decisions and increase the efficiency of applied N in corn production systems in Illinois. The objectives include: 1) monitoring inorganic soil N status following application of several commonly used forms and timings of N fertilizer across a number of sites in Illinois, 2) model calibration and validation to produce site-specific estimates of soil N status and losses (models will combine collected field results with publicly available soils and climate data to produce geo-referenced estimates that are sensitive to N management practices, soil type, and up-to-date weather information), and 3) online posting of results in near real-time to allow growers to see how weather events and current crop growth conditions may be influencing soil N availability in their area based the measured and modeled data. This presentation will focus on field data results (objective 1) and online posting of those results (part of objective 3) while also discussing the model development process (objective 2). Emphasis will be given to the potential for model outputs and decision support tools to improve N management decisions and reduce N losses in Illinois.