DESENVOLVIMENTO, PRODUTIVIDADE E ESTADO NUTRICIONAL DE MILHO FERTIRRIGADO COM ÁGUA RESIDUÁRIA DE PSICICULTURA E SUINOCULTURA DILUÍDAS

Abstract

Corn (Zea mays L.) is one of the most important cereals in the world, being a nutrient-demanding crop, especially nitrogen, so alternative sources of nutrients for crop have agronomic, environmental and economic benefits, especially when related to nitrogen supply to the plant. As stated above, the aim of this study was to evaluate the levels of chlorophyll in the leaves, the dry matter and grains production, the nutritional balance of macronutrients in fertigated corn by drip with swine and fish farming waste water at different dilutions, as well as the hydraulic performance of the irrigation system used. The experiment was carried out in plastic vases, arranged in the open, at the experimental station of the Instituto Federal Goiano - Campus Rio Verde – GO, Brazil. The soil used was classified as dystrophic Red Latosol, Cerrado phase, with a clay texture. The experimental design used was in randomized blocks, analyzed in a 2 × 4 split plot scheme, with three replications. The treatments consisted of two sources of waste water (fish and swine farming) diluted in four proportions of water supply, being: recommended dose of waste water + 0, 25, 50, 75% of its volume in water supply. The levels of chlorophyll in leaves, the dry matter accumulation of the aerial part and the productive parameters were evaluated. In addition, the nutritional status of corn at flowering and, after harvest, the accumulation, extraction and export of macronutrients were evaluated. The surface drip irrigation system had its hydraulic performance evaluated after the wastewater application, in which, with the data of the drippers average flow, the hydraulic performance of the system was determined based on the calculations of uniformity coefficients, HSPA standard efficiency, relative flow, variation coefficient and the degree of clogging. The source of swine wastewater provides the highest content of chlorophyll a, chlorophyll b, total chlorophyll and SPAD reading at the end of the corn cycle. The highest dry mass of stalk, dry mass of the aerial part and dry matter partition of stalk in relation to the dry matter of the aerial part is obtained when using the swine wastewater source. Swine wastewater provides the largest size, dry mass and grain yield and corn harvest index. Swine and fish farming wastewater have the potential to supply the nutritional demand of corn, and may partially replace mineral fertilization. Regarding the nutritional aspect of the plant, swine wastewater is the best option for fertilizing the corn crop, in any of the dilutions, compared to fish farming water. Regardless of the wastewater source used in corn fertigation, the increase in dilution provides the best hydraulic performance of the surface drip irrigation system after fertigation. The use of the drip irrigation system operating with swine and fish farming wastewater does not compromise the uniformity of water distribution to the plants.