Thermal imaging and EMI data fusion to delineate homogeneous management zones based on the variability of soil hydraulic properties

Mapping soil electrical conductivity (EC) through geophysical proximal soil sensors is one of the most reliable and commonly used technique to obtain quick and high resolution information about soil spatial variability. Nevertheless, spectral data collected in the visible, near-infrared and thermal infrared regions can be combined with EC data to better characterize the soil variability and to improve the delineation of homogeneous site specific management zones (SSMZs) required in precision agriculture for variable-rate irrigation and fertilization management. The recent scientific literature emphasizes the use of thermal sensors mounted on unmanned aerial vehicles to evaluate the spatial distribution of soil moisture, based on the acquisition of thermal images of bare soils. In particular, the method of soil apparent thermal inertia (ATI) can be applied for this purpose. Objective of this work is the fusion of EC and ATI data to characterize the spatial variability of soil hydraulic properties, and finally to improve SSMZs delineation. The main outcome of this study concerns the elaboration and the comparison of three SSMZs maps, the first derived from EC data, the second from ATI data, and the third from EC and ATI data fusion. The results highlight how geophysical and thermal data may provide complementary information useful to improve the delineation of SSMZs.