ÁGUA RESIDUÁRIA DE SUINOCULTURA COMO FONTE ALTERNATIVA À ADUBAÇÃO MINERAL NITROGENADA PARA A CULTURA DO MILHO NO CERRADO

Abstract

Corn (Zea mays L.) is one of the most important cereals in the world, and is considered a nutrient-demanding crop, especially nitrogen, which is the nutrient required in the greatest quantity by this cereal and the one that most burdens production costs. Thus, the adoption of alternative nitrogen sources supply for corn crops presents agronomic, environmental and economic benefits. In this context, the objective of this study was to evaluate the growth, development, grain yield and production cost of corn (hybrid AS1820PRO3), subjected to fertigation with swine wastewater and mineral fertilization with urea, in Cerrado Red Latosol. The experiment was conducted in two harvests, at the experimental station of the Instituto Federal Goiano – Campus Rio Verde – GO. The soil used was classified as dystroferric Red Latosol, Cerrado phase, with clayey texture. The experimental design was in randomized blocks, with five replications, totaling 25 experimental plots. The treatments consisted of five proportions of swine wastewater (SWW) via fertigation supplemented with broadcast urea application, based on the recommended dose of nitrogen topdressing in corn crops, being: T1 - 0SWW+100Urea: 0% of the nitrogen dose applied via fertigation with SWW and 100% of the nitrogen dose applied broadcast via urea; T2 - 25SWW+75Urea: 25% of the nitrogen dose applied via fertigation with SWW and 75% of the nitrogen dose applied broadcast via urea; T3 - 50SWW+50Urea: 50% of the nitrogen dose applied via fertigation with SWW and 50% of the nitrogen dose applied broadcast via urea; T4 - 75ARS+25Urea: 75% of the nitrogen dose applied via fertigation with ARS and 25% of the nitrogen dose applied broadcast via urea; T5 - 100ARS+0Urea: 100% of the nitrogen dose applied via fertigation with ARS and 0% of the nitrogen dose applied broadcast via urea. The experimental plots consisted of five 5 m long rows, totaling an area of 281.25 m2. The treatments were applied as topdressing in the corn crop at the V4 and V6 phenological stages. The chlorophyll contents in the leaves, growth parameters, dry matter accumulation, corn production parameters and economic parameters of fertigation with swine wastewater were evaluated. Pig wastewater as a total replacement for urea results in satisfactory agronomic efficiency, demonstrating its potential as an alternative nitrogen source for corn crops. However, due to transportation obstacles, its cost per hectare is higher. Therefore, from an economic point of view, it is recommended to partially replace urea with pig wastewater, using the ratio 50ARS+50Urea.