Salinização de solos sob aplicação de rejeito de dessalinizadores com e sem adição de fertilizantes

Abstract

The use of waters under appropriate conditions of management should not offer great problems for irrigation. In the semi-arid area of the Brazilian Northeast that presents a hydrological deficit, the inadequate management of the irrigation practice, allied to the incomplete leaching and to the intense evaporation, result in an increasing of the salts in the surface and/or undersurface layers of the soil due to the insufficient salt balance commonly verified in those areas. In this way, aiming to evaluate the soil salty process of the Moxotó – PE irrigation project, submitted to the application of both rejects of desalt machine and of desalt machine after use in the lettuce cultivation in the nutrient laminate flow (type NFT) as a hydroponic technical system, it was realized an experiment in soil columns installed in the Soil Mechanic and Residue Use Laboratory of the Universidade Federal Rural de Pernambuco. The treatments were delineated in a randomized blocks with factorial arrangement of two soils (clayly and sandy), two types of reject (reject of desalt machine and reject of the hydroponic system) and five salty concentrations (0,53; 1,16; 1,90; 3,52; 4,60 dS m ֿ¹), with three replicates. The evaluated components in the extract of the saturated paste were the electric conductivity (EC), soluble cations and the relationship of sodium adsorption relationship (SAR). In the leached solution it was determined the electric conductivity, the soluble sodium, the pH. The calcium, magnesium and potassium soluble concentrations increased independently of the quality of the reject used, and this increasing was proportional at the electric conductivity levels applied. The use of the irrigation volumes equivalent to three volumes of pores, using rejects both of desalt machine and of hydroponic system didn't provide the neither salty process nor sodium process of the soils studied (EC > 4,00 dS m-¹ and SAR > 13). The drainage water was characterized as a material potentially pollutant in terms of the concentration of soluble salts, verifying decreasing in the saturated hydraulic conductivity values of the soils.