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Track: Agriculture
Su Liu
U.S. Dept of Agriculture
PO Box 6567
National Cartography and GIS Center
Fort Worth, TX 76115
Telephone: 817-334-5559
Fax: 817-334-5550
E-mail: sliu@ftw.nrcs.usda.gov
Jerry Lemunyon
Using GIS to Manage Nutrients and Pests at the Field Level
Defining Issue: Nutrient and pest management are important components of a resource management system. Both conservation practices require historic data (soils, climate, crop yields) and dynamic data (crop rotation, nutrient requirement, pest control). Some of the information is dynamic, changing each growing cycle, yet draws on the attributes of the field (soil, topography, climate) to determine actual management levels. It is proposed that a GIS system be developed that can follow the nutrient and pest management systems and provide information for seasonal decisions at the field level. These decisions are normally: how much nutrients are required? Where are the sensitive areas of the field? What is the history of pests in the field? Can pests be expected this growing season? What are the management options for this growing season? This article describes the use of GIS for the management of the nutrients and pests in the upper North Bosque River watershed area. GIS Solution: GIS was used to perform
the function of 1) keeping a history and tracking the boundary (changes) and land use, and the associating attribute data of a field over time; 2) managing the nutrients or pests by monitoring the area (subfield) that overlaps land use and the sensitive areas; and 3) displaying, analyzing and querying the information. Methodology: A field can be attached with the historic attributes (soils, yield, climate, soil test results, topography). The historic attributes can be used to delineate sensitive areas that need special management. Some attributes can be used to do real time calculations at the field level. One example would be nitrogen mineralization from previously applied organic amendments. The real-time calculations can be put into alternative management scenarios that become the basis for making decisions. Alternative scenarios can also be used to assess risk to the environment. There is a requirement for linkage with nutrient and pest management tools and indexes. Some of the nutrient and pest
management tools and indexes that can be linked are RUSLE and RWEQ for prediction erosion, NLEAP for nitrogen leaching, phosphorus index for loss potential, SPISP and NAPRA for pesticide risk, and TR - 55 for runoff potential. Decisions can be made and management completed to create a GIS database that can be used for seasonal evaluation or developing a season-by-season GIS database to monitor the effects of nutrients and its distribution over time. Potential data sets can be compiled for the entire watershed for identifying or targeting the critical microwatershed areas and balance nutrient imports to exports. Some of the attribute layers that would be used include roads, buildings, elevations, soils, streams, land use, field boundaries, sensitivities of areas to nearby waste disposal sites, and vulnerability of underground water.
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