Efeito da carga hidráulica e qualidade de água na uniformidade de sistema de irrigação por gotejamento

Abstract

One of the factors that should be considered when purchasing an irrigation system is related to its application uniformity. It has a direct influence on agricultural productivity, which tends to increase with the improvement of this uniformity. The fertigation through drip irrigation system provides better application uniformity, therefore contributing to water and energy economy. The cassava wastewater provides a serious environmental problem when released directly into water bodies, and due to this, the application in the soil has shown beneficial effects when used in agriculture as organic fertilizer. Thus, the objective of this study was to evaluate four different treatments with six replicates each, considering two factors: hydraulic loading (1,0 and 1,5 m) and type of applied water: clean water and diluted cassava processing wastewater. The system was installed in the Experimental Center of Agricultural Engineering (NEEA), belonging to the State University of West of Paraná (UNIOESTE), in Cascavel - Paraná. Physicochemical characterization of water was performed to determine the clogging risk to the system by monitoring the parameters of pH, electrical conductivity (EC), dissolved solids (DS) and turbidity and determined the coefficients of flow variation (CV), emission uniformity (EU) and Christiansen Uniformity (CUC). In both treatments, with a hydraulic load of 1,5 m, 25 tests were performed in order to control statistical techniques and establishment of process capacity indices to the coefficients obtained. In treatments with cassava processing wastewater there was a decrease in the values of flow over time, with an average reduction of 20,02 and 18,84% for the hydraulic load of 1,0 and 1,5 m, respectively. The water used for irrigation in drip system showed pH values that can cause severe risk of clogging the equipment used. The quality of the diluted cassava processing wastewater used in the fertigation treatments had turbidity values outside the standards of CONAMA. The CV and the EU showed higher results in the treatment of irrigation with a hydraulic load of 1.5 m, being classified as excellent. Only the individual measures Shewhart chart of the CUC in the trials of fertigation was found in statistical control. The values of process capability indices showed a relationship with the coefficient of uniformity which are inversely proportional to CV and and directly proportional to EU and CUC. The process capability index was able to diagnose whether irrigation has the ability to maintain control and constant, or whether it will be able to maintain acceptable levels of uniformity.