Monitoring Soil Erosion Using Land Cover and Tillage Derived from Satellite Imagery

Under the North Sea Agreement, Norway was obliged to reduce the discharge of nutrient salts from agricultural fields by 50% within 1995. Remote sensing from satellites can be used to monitor soil tillage in the areas concerned. An experiment was carried out which shows that it is possible to classify the different agricultural classes with a high degree of accuracy using LANDSAT TM images. However, cloud conditions in late autumn makes it interesting to investigate the use of satellite SAR images to detect tillage. The results of classifying SAR images which have been speckle reduced, show that ploughed and stubble fields can be discriminated with a high degree of confidence when the soil moisture level is high. The best result is obtained using a field-by-field classification method. In an operational system, geocoded SAR images should be used as a supplement to the optical images.