Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/20/2002
Publication Date: 11/20/2002
Citation: Giasson, E., Bryant, R.B., DeGloria, S.D. 2002. GIS-based spatial indices for identification of potential phosphorus export at watershed scale. Journal of Soil and Water Conservation. 57(6):373-381. Interpretive Summary: The amount of nutrients transported by surface runoff to water bodies depends on many geographic factors and management practices, such as soil cover, land use, crop management, and timing, rate and method of manure application. While obtaining field-based information about the type and effectiveness of management practices consumes resources and is sometimes unfeasible, computerized spatial analysis of digital geographic informatio offers a rapid and low cost alternative means of identifying land areas that may contribute to water quality problems. Many land characteristics are available in map form, both analog and digital, that can be used to assess the potential of a site to export nutrients. Spatial indices for identifying potential pollution resulting from manure spread on agricultural lands were developed for evaluating lands in support of decision and policy-making. These indices were applied in the Cannonsville Reservoir Basin, in Delaware County, New York, USA. Results demonstrate th potential for using the index approach for selecting priority areas for enrolling lands in programs like the Conservation Reserve Program. The indices also identified areas of croplands or pastures where conservation practices could be targeted to result in large reductions of potential pollution per unit of area.
Technical Abstract: Spatial indices for identifying potential pollution resulting from manure spread on agricultural lands were developed for evaluating lands in support of decision and policy-making. An existing nutrient delivery ratio was modified by calculating actual distance that water would have to travel to reach a stream and was further tailored to better represent runoff source areas in New York State by incorporating soil drainage class. The Animal Manure Potential Pollution Index (AMPPI) was derived from this modified delivery ratio and animal population census data. The AMPPI and other derived indices use geographical information and nutrient application data to identify and rank geographical areas with respect to potential nutrient export to streams. These indices were applied in the Cannonsville Reservoir Basin, in Delaware County, New York, USA. Results demonstrate the potential for using the AMPPI and its derivate indices for selecting priority areas for implementing conservation practices or enrolling lands in programs lik the Conservation Reserve Program. The results show that conservation practices would result in large reductions of potential pollution per unit of area when implemented in specific areas of croplands or pastures with high AMPPI. Additionally, an efficient way to reduce total nutrient concentration in stream waters would be to enroll in conservation programs those farms located in subbasins with high nutrient export per unit area, which correspond to areas with high animal density.