RELATIONSHIP BETWEEN SOIL ORGANIC-CARBON AND LANDSAT TM DATA IN EASTERN WASHINGTON

Analysis of digital-data from Landsat Thematic Mapper (TM) images has been proposed as a complementary method for estimating surface organic carbon levels of soils. Our objective was to establish the relationsh ip between soil organic carbon (SOC) and a selected transformation of TM band ratios corresponding to the soil component values in the Palou se region of eastern Washington State. TM data and surface SOC measure ments were obtained and evaluated using linear regression methods at f our field-sites. Results showed that regression models, each pooled wi th two field-sites (Plaza and Pullman, Thera and St. John) were approp riate for the data. Significant (P less-than-or-equal-to 0.01) regress ions between surface SOC and TM data were detected for both functions, and r2 values (0.88 and 0.71) also indicated a strong linear associat ion. Plots of TM data and surface SOC showed a general trend toward hi gher SOC with higher Tm values, suggesting a useful relationship.