Decision support for nitrogen management in tile-drained agriculture
Farmers will adopt alternative management systems to improve water quality more readily if they understand how those management alternatives affect the release of contaminants, crop yields, and ultimately, their net income. We propose a method to address these issues by integrating observed data from field experiments, a comprehensive simulation model, review by local experts, and application through a decision support system by technically trained conservationists. An example for reducing nitrogen loading from tile-drained corn and soybean production in Iowa demonstrates the approach. Fourteen years of observed data from 30 research plots on the Northeast Research and Demonstration Farm near Nashua, Iowa were used to calibrate the Root Zone Water Quality Model (RZWQM) to simulate the effects of 35 management systems on crop yields and nitrogen (N) loadings into tile drains. The EconDocs tool was used for an economic analysis of the management effects. An Expert Panel reviews the simulations and the long term average annual management effects. Those management effects, as well as the daily values of variables that describe the crop growth and nitrogen loading in tile flow processes, are put into a database. As part of the conservation planning process, Conservationists and farmers would use the database inside a decision support system to select management systems that meet the farmers' goals and reduce water quality problems.
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