|Mueller Warrant, George|
Submitted to: Seed Production Research at Oregon State University
Publication Type: Experiment Station
Publication Acceptance Date: 2/20/2008
Publication Date: 4/1/2008
Citation: Mueller Warrant, G.W., Whittaker, G.W., Griffith, S.M., Banowetz, G.M., Garcia, T.S., Giannico, G.R., Mccomb, B.C. 2008. Three-year gis of western oregon grass seed cropping practices. Seed Production Research at Oregon State University.127:37-40. Interpretive Summary:
Technical Abstract: High quality georeferenced data on crop production practices and other land uses is critical but often lacking in undertakings, such as the USDA Conservation Effects Assessment Program (CEAP), that seek to measure the effectiveness of conservation practices in achieving their goals. A multi-year CEAP project involving collaboration between USDA-ARS-NFSPRC and OSU’s Dept. of Fisheries and Wildlife was designed to identify and characterize the tradeoffs among ecosystem services inherently present in current agricultural production systems in the Willamette Valley. To enable the application of SWAT to our research problem, we established a three-year GIS of western Oregon grass seed cropping practices for use by the CEAP project using information from two sources. First, fall and spring drive-by censuses were conducted from 2004 through the present of most grass seed fields in the Calapooia River watershed. Spring drive-by surveys of randomly selected fields from stratified samples of agricultural fields also were conducted in neighboring counties. Second, fields from the Calapooia census and the multi-county survey were used to train the classification of series of commercially available Landsat satellite images taken during each growing season. Remote sensing classification allows the GIS to expand from the fields actually visited in the drive-by census and survey to nearly the entire Willamette Valley. The most striking trend present in the GIS was a reduction in the number of perennial ryegrass fields with a corresponding increase in tall fescue. The total number of tall fescue fields in the Calapooia River watershed increased from 551 in the 2004-2005 growing season to 709 in the 2006-2007 growing season, while perennial ryegrass dropped from 464 to 356 fields over the same period. A related trend was the increase in number of spring plantings of grass seed crops from 46 fields in the first year to 122 fields in the third year, mostly tall fescue. Use of full straw chop volunteer stand reseeding in annual ryegrass also increased over the three year period in absolute numbers of all fields and in the proportion of fields with unchanged boundaries classified in all three years. Even with the increase in full straw chop volunteer stand reseeding of annual ryegrass, this production approach appears to be only used on approximately 20% of all annual ryegrass fields.