Mapping Soil Clay Content and Hydraulic Properties over an Agricultural Semiarid Plain Using Remote Sensing and Interpolation Techniques

Clay content is an important parameter governing hydrodynamics property of soils and consequently crucial to environmental management and agricultural development. The present study aims to use the textural middle infrared index (MID index) product of Landsat-8 Operational Land Images to map clay content over the Haouz plain (Central Morocco). The clay content was mapped at 30 m grid spatial resolution based on the relationship between the MID index and a large set of soil samples. Over the areas covered by green vegetation, the clay content was predicted using the ordinary cokriging technique. Then, this information was used to derive soil hydraulic properties such as the field capacity (θfc), the wilting point (θwp) and the saturated hydraulic conductivity (Ksat) by using different pedotransfer functions. The validation of the maps was performed by using independent soil samples and measurements. The results showed that the clay content is significantly correlated to MID index. The ordinary cokriging improved mapping of clay content over the Haouz plain (R2 = 0.70, RMSE = 3.5%). The obtained maps of θfc, θwp and Ksat revealed a good correlation between the simulated values and the measured values.