Salic horizon characterization in soils from the irrigated area of Moxotó, PE, Brazil

Abstract

Aiming to determine the percentage of salts in soil (Pss) and to characterize salic horizon, thirty soil samples with high salt content were selected from the ones sampled during the soil salinity survey of the irrigated area of Moxotó, PE, Brazil. The percentage of salt in the soils was determined by both direct method using the residue of the saturation extract oven dried to constant weight at 105°C (DR) and by indirect method using the equation developed by Richards which is a function of both the electrical conductivity (EC) of the extract and the percentage of water in the saturated paste. From the thirty analysed samples, ten were characterized as salic horizon when the direct method was used and only three were characterized as such when the equation developed by Richards was used. It can be concluded that for soils under consideration, with values of electrical conductivity higher than 30 mmhos/cm/25°C, Richards equation is not recommended. However, it can be used for soils with EC lower than 30 mmhos/cm/25°C, until results of new research work confirm or deny it. A high linear correlation was found between the oven dried residue (DR) of the saturation extract and the electrical conductivity. This relationship is shown by the regresion equation Y (DR) g/l = -10.45 + 1.25.EC (mmhos/cm) with r² = 0.963.