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United States Department of Agriculture

Agricultural Research Service

Research Project: CONSERVATION EFFECTS ASSESSMENT IN THE SOUTH GEORGIA LITTLE RIVER Title: Satellite Mapping of Conservation Tillage Adoption in the Little River Experimental Watershed, GA

Authors
item Sullivan, Dana
item Strickland, Timothy
item Masters, M - FLINT RIVER WATER POLICY

Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 30, 2007
Publication Date: May 1, 2008
Citation: Sullivan, D.G., Strickland, T.C., Masters, M.H. 2008. Satellite Mapping of Conservation Tillage Adoption in the Little River Experimental Watershed, GA. Journal of Soil and Water Conservation. 63(3):112-128. GRACEnet Publication.

Interpretive Summary: Conservation tillage is a commonly adopted best management practice for improving soil quality and reducing erosion. However, there are currently no methods in place to monitor conservation tillage adoption at the watershed scale. The primary objective of this study was to evaluate the utility of Landsat TM data as a tool to map conservation tillage adoption in the Little River Experimental Watershed. Ground truth data consisted of a windshield survey of 138 sites. Each site was identified as conventional or conservation tillage and used to develop a relationship between tillage regime and satellite derived reflectance. The resulting satellite derived map accurately predicted conservation tillage 71-78 % of the time. Models used to map conservation tillage adoption were created using 44 ground control points and validated against 94 ground control points. Results are encouraging and suggest that currently available satellite imagery can be used to map conservation tillage adoption with a minimum amount of ground control points. GRACEnet Publication.

Technical Abstract: Conservation tillage is a commonly adopted best management practice for improving soil quality and reducing erosion. However, there are currently no methods in place to monitor conservation tillage adoption at the watershed scale. The primary objective of this study was to evaluate the utility of Landsat TM data as a tool to depict conservation tillage in a small Coastal Plain watershed. Satellite imagery were used to calculate four commonly used indices: normalized difference vegetation index, crop residue cover index, normalized difference tillage index and the simple tillage index. Ground truth data consisted of a windshield survey, assigning each site a tillage regime (conventional or conservation tillage) at 138 locations throughout the watershed and surrounding areas. A logistical regression approach was used on two subsets of the data set (n = 22 or n = 40) to determine the minimum number of ground control points necessary to develop a conservation tillage model. The most accurate model was re-applied to the satellite image and evaluated using an independent sample of 94 survey sites. Results indicate that the normalized difference tillage and simple tillage indices performed best, with an overall accuracy of 71 and 78 % for models developed using n = 22 and n = 44 sample locations, respectively. Errors were typically in the form of commission. Results are encouraging and suggest that currently available satellite imagery can be used for rapid assessment of conservation tillage adoption using a minimum amount of a priori information.

Last Modified: 11/20/2014