Author
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Mueller Warrant, George |
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Griffith, Stephen |
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Whittaker, Gerald |
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Submitted to: Meeting Abstract
Publication Type: Abstract Only Publication Acceptance Date: 7/31/2006 Publication Date: N/A Citation: N/A Interpretive Summary: Agricultural landuse dominates many watersheds across the US, and detailed, spatially-explicit knowledge of the management practices employed in crop production could serve to identify nonpoint sources of nutrients, sediment, and pesticides in our nation's waters. Such knowledge might also play a pivotal role in quantifying benefits of on-farm conservation practices, whether mandated or optional aspects of government farm programs, NGO-supported projects, or farmer-based initiatives. Agricultural landuse in lower elevations of the Calapooia River Watershed in Linn County, Oregon, is dominated by grass seed production. Fields producing seed of perennial grass species are undisturbed by tillage during the three to six or more years that such stands are kept in production, following which stands are destroyed and a variety of rotational crops grown. While tillage is commonly employed during stand removal and seedbed preparation for new plantings of both perennial and annual species, an increasing diversity of no-till practices are being developed in response to soil erosion/water quality concerns and the increasingly high cost of diesel fuel. In support of collaborative projects monitoring nutrients and sediment in water and measuring diversity and abundance of biotic indicators of ecosystem health ranging from invertebrates, amphibians, and fish to waterfowl and passerine birds, we have committed ourselves to the development of a GIS detailing agricultural landuse practices from 1994 through the present. Nearly complete censuses of crops grown and partial enumerations of conservation practices employed were developed from roadside observations in the agricultural portion of the Calapooia River Watershed in the 2004-05 and 2005-06 cropping years. Ground-truth census data are being combined with more limited surveys of grass seed production fields in other western Oregon counties to develop and validate remote sensing classification procedures needed to extend our database across the Willamette Valley. USDA-FSA common land unit (CLU) shapefiles of agricultural fields have been used to aggregate pixels classified from remotely-sensed data, improving overall classification accuracy an additional 10%. Separate records of certified grass seed production comprising approximately 50% of all seed fields in Linn County, Oregon, will be used along with a series of late summer Landsat images to develop and validate remote-sensing classification procedures for the entire period from 1994 to 2003. Preliminary analyses have revealed the presence of 3-fold variation in proportion of fields tilled among sub-basins within the Calapooia River Watershed. The Soil & Water Assessment Tool (SWAT) has been calibrated for the Calapooia River Watershed, and is being used to test for possible linkage between variation in soil disturbance and water quality measurements over time among the sub-basins. Technical Abstract: Agricultural landuse dominates many watersheds across the US, and detailed, spatially-explicit knowledge of the management practices employed in crop production could serve to identify nonpoint sources of nutrients, sediment, and pesticides in our nation's waters. Such knowledge might also play a pivotal role in quantifying benefits of on-farm conservation practices, whether mandated or optional aspects of government farm programs, NGO-supported projects, or farmer-based initiatives. Agricultural landuse in lower elevations of the Calapooia River Watershed in Linn County, Oregon, is dominated by grass seed production. Fields producing seed of perennial grass species are undisturbed by tillage during the three to six or more years that such stands are kept in production, following which stands are destroyed and a variety of rotational crops grown. While tillage is commonly employed during stand removal and seedbed preparation for new plantings of both perennial and annual species, an increasing diversity of no-till practices are being developed in response to soil erosion/water quality concerns and the increasingly high cost of diesel fuel. In support of collaborative projects monitoring nutrients and sediment in water and measuring diversity and abundance of biotic indicators of ecosystem health ranging from invertebrates, amphibians, and fish to waterfowl and passerine birds, we have committed ourselves to the development of a GIS detailing agricultural landuse practices from 1994 through the present. Nearly complete censuses of crops grown and partial enumerations of conservation practices employed were developed from roadside observations in the agricultural portion of the Calapooia River Watershed in the 2004-05 and 2005-06 cropping years. Ground-truth census data are being combined with more limited surveys of grass seed production fields in other western Oregon counties to develop and validate remote sensing classification procedures needed to extend our database across the Willamette Valley. USDA-FSA common land unit (CLU) shapefiles of agricultural fields have been used to aggregate pixels classified from remotely-sensed data, improving overall classification accuracy an additional 10%. Separate records of certified grass seed production comprising approximately 50% of all seed fields in Linn County, Oregon, will be used along with a series of late summer Landsat images to develop and validate remote-sensing classification procedures for the entire period from 1994 to 2003. Preliminary analyses have revealed the presence of 3-fold variation in proportion of fields tilled among sub-basins within the Calapooia River Watershed. The Soil & Water Assessment Tool (SWAT) has been calibrated for the Calapooia River Watershed, and is being used to test for possible linkage between variation in soil disturbance and water quality measurements over time among the sub-basins. |
