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Title: DECISION SUPPORT FOR NITROGEN MANAGEMENT IN TILE-DRAINED AGRICULTURE 1825

Author
item Heilman, Philip - Phil
item Malone, Robert - Rob
item Ma, Liwang
item Hatfield, Jerry
item Ahuja, Lajpat
item AYEN, J. - NRCS
item BOYLE, K. - NRCS
item KANWAR, R. - IOWA STATE UNIVERSITY

Submitted to: Environmental Modelling & Software
Publication Type: Proceedings
Publication Acceptance Date: 6/1/2006
Publication Date: 7/17/2006
Citation: Heilman, P., Malone, R.W., Ma, L., Hatfield, J.L., Ahuja, L.R., Ayen, J., Boyle, K., Kanwar, R. 2006. Decision support for nitrogen management in tile-drained agriculture. In: Voinov, A., Jakeman, A.J., Rizzoli, A.E. (eds). Proceedings of the iEMSs Third Biennial Meeting: "Summit on Environmental Modelling and Software". International Environmental Modelling and Software Society, Burlington, USA, July 2006. CD ROM.

Interpretive Summary: This paper outlines an eleven step process to define, populate, and apply a database of management effects to support conservation planning by the NRCS. A case study for reducing nitrogen loading from tile-drained corn and soybean production in Iowa presents the approach. Basic information from the case study is presented, although only the first five steps, through calibration and validation of a simulation model against observed data, have been completed. The strength of the approach is the ability to integrate the best available data to quantify management effects over a large area. The main weakness of the approach is the need for a substantial initial investment to create the database. Once populated, customized views of the database would be available for farmers, NRCS conservationists, and researchers.

Technical Abstract: 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. 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 alternative management systems on crop yields and N loadings into tile drains. 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, farmers would use a decision support system with the database, under the guidance of the Natural Resources Conservation Service, to select management systems that meet the farmers' goals while reducing water quality problems.