Indicators Based on Apparent Electrical Conductivity Measurements to Detect Changes in Soil Properties Under Irrigation

Complementary irrigation is an agronomic practice that consists of applying sheets of water when the soil moisture does not satisfy the water needs of the crop to achieve maximum yields. However, this practice can lead to soil salinization when electrical conductivity of irrigation water exceeds certain limit values. The objective of this work is to determine the efficiency of indicators based on the ECa, measured with proximal sensors, as a rapid characterization of variability of some soil properties under complementary irrigation. INDICATOR ratios were calculated using the apparent electrical conductivity obtained from resistivity and electromagnetic induction measurements in two areas: one under irrigation and another rainfed. Some physico-chemical soil properties measured in laboratory at the same sites were compared with those indicators in the two areas. The indicators using the measurements with the resistivity sensor in soils under irrigation were efficient to determine, rapidly, changes in soil salinity and sodicity due to water application. They were also effective to detect variability in soil humidity when volumetric water content is at least slightly greater in irrigation than rainfed area. The indicator using apparent conductivity from electromagnetic induction measurements was efficient to detect changes in other edaphic properties and their spatial distribution.