|Shaffer, M - USDA ARS, RETIRED|
Submitted to: Soil and Water Conservation Society Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: February 16, 2007
Publication Date: July 22, 2007
Citation: Delgado, J.A., Shaffer, M.J. 2007. Testing of a Nitrogen Index to Assess N Management Practices With GIS. Proc. of the Soil and Water Conservation. To Identify High-Risk Cropping System/Landscape Combinations . Soil and Water Conservation Society Proceedings. Technical Abstract: Shaffer and Delgado (2002) reported that there is the need for quick nutrient management tools capable of quickly assessing the effects of management practices on nitrogen losses. Tier-one tools were defined as tools capable of conducting quick assessments of the effects of management on N losses using minimum information. Tier-two tools were defined as simple mechanistic models capable of evaluating the effects of N management on N losses. Tier-three tools are more complex simulation models with a large number of N pools that require more intensive data sets. We tested the Delgado et al. (2006) Nitrogen-Index spreadsheet tier-one tool approach to assess the effects of management practices on residual nitrate-nitrogen (NO3-N) available to leach and N losses across the landscape. Management practices, such as N fertilizer inputs, irrigation, basic chemical and physical soil information, and annual and seasonal precipitation, were entered into the N-Index. The N-Index evaluations were compared to the observed residual soil NO3-N values. The N-Index NO3-N leaching losses assessment was compared to tier-two simulated NO3-N leaching. The N-Index results were exported to GIS tools for presentation of observed results and identification of hot spots. Preliminary results found that the N-Index residual soil NO3-N assessment values were correlated to simulated NO3-N leaching values (P<0.01). The N-Index can be combined with GIS tools for identification of sensitive areas. The N-Index appears to be a potential tier-one tool capable of assessing the effects of nitrogen management practices on N losses across high-risk cropping system/landscape combinations (P<0.01).