WATER QUALITY INFLUENCE IN DISPERSIVE BEHAVIOR OF THE YELLOW-RED LATOSOL CLAY

Abstract

This work aimed to study the effect of irrigation water with different electric conductivities (EC), combined with different Sodium Adsorption Relation (SAR) values on the dispersion of clay in Yellow-Red Latosol (YRL). The samples were collected in the B horizon of the soil originated from Viçosa, MG, with predominance of the clay minerals kaolinite. The soil was characterized in physical, chemical, and mineralogical terms. The treatments corresponded to percolation of NaCl and CaCl2 solutions prepared so as to have six different EC values (200; 500; 1.000; 2.000; 4.000 and 8.000 ?S cm-1) and five SAR (0, 5, 10, 20 and 40 mmolc L-1), with three repetitions, arranged in a randomized block design. The application of the solutions was made in vertical column and constant load permeameters. The solution was applied until effluent EC approached that in applied solution (C/C0 = 1,0). To evaluate the effect of the solutions applied on the soil structure, the contents of clay dispersed in water (CDW) were quantified. YRL presented non-dispersive behavior in all treatments. The YRL pH close value to its PCZ and the aluminium changing saturation complex where, apparently, important factors to the clay dispersivity control on this soil class.