SOIL-MOISTURE CONTENT GROUND DATA FOR REMOTE-SENSING INVESTIGATIONS OF AGRICULTURAL REGIONS

Ground-data quality is an important issue in the analysis of remotely-sensed data. Since the results of such an analysis are evaluated against the ground data these ground data must be accurate. Two issues affecting the quality of soil moisture content ground data are investigated in this paper. These are the laboratory procedures employed in its estimation and the effect of cultivation practices on the distribution of surface soil moisture in the field. Laboratory procedures commonly used may not always be appropriate and different approaches are likely to give estimates of variable accuracy. Cultivation practices were found to produce significant variations in soil moisture distribution, with over 10 per cent difference in soil moisture content estimates between the top and bottom of a ridged soil. Ground data collectors using different sampling designs and adopting dissimilar laboratory techniques may therefore produce considerably different estimates of the soil moisture content. Consequently ground-data collection programmes should be fully documented, especially if the results obtained by different research groups are to be compared or merged, so that users may be aware of the quality of the data recorded