Determination of Soil Physical Properties and Pre-Sowing Irrigation Depth from Electrical Resistivity, Moisture, and Salinity Measurements

Abstract

Seeds require adequate soil moisture prior to planting, and pre-sowing irrigation depth (PSID) represents the optimum seed moisture level. This work proposes a new methodology to obtain soil physical properties and PSID, that includes the application of the electromagnetic profiling method (EMP) as a fast and non-invasive technique. Soil electrical resistivity measurements obtained from an EMP survey are combined with soil moisture and salinity information as experimental input for the PetroWin program. The PetroWin program uses Ryjov’s theoretical model to determine fines content and porosity, and then, PSID values are determined. At the study site, variations in soil resistivity were controlled by variations in fines content and soil moisture, and not by variations in soil salinity. The rooting depth of the crops was limited by a soil thickness of 0.6 m. A PSID between 8 and 9 cm was determined for the site, resulting in a total water volume required of 5313 m3 to ensure that soil moisture reaches the field capacity. The proposed methodology constitutes an effective and efficient tool for the determination of the physical properties and irrigation parameters of agricultural soils and, consequently, for the sustainable use of irrigation water.