Água residuária de suinocultura aplicada em cobertura na cultura do milho com cultivo sequencial de aveia preta.

Abstract

The application rates of swine wastewater used in crop production should be enough to meet the demand for plant nutrients. Thus, it is justified the need to research its use and management as a fertilizer for applications to be made according to technical recommendations. Taking into account its features, soil characteristics and crop were taken into account. In this context, the aim of this study was to monitor wastewater influence as topdressing to maize (Zea mays L.) and black oats (Avena strigosa Schreb.) crops in sequence. Five rates of wastewater application (0; 100; 200; 300 e 537 m3ha-1 equivalents to 0; 11,2; 22,3; 33,5 and 60 kg ha-1 of N respectively, based on an average concentration of N on swine wastewater) were tested in four replications each. In maize and black oats were performed foliar and plant tissue analysis. In the soil porosity, bulk density, soil water content, pH, carbon, CEC (Cation Exchangeable Capacity), alkaline saturation, potential acidity and nutrients were determined at the final maize and black oats cycles. The topdressing on maize crop sowing crop increased foliar content of P, N e Mn, decreased the foliar content of K and Mg. In black oats crop the residual effects provided 87% dry mass increase, chlorophyll content, foliar contents of N, Ca and Na, and decreased the relation between leaf/stem and contents of P, K, Mg and Cu. The crops under swine wastewater treatment did not show nutrients deficiency. There was a decrease on the macropores and total soil porosity when the application rate of swine wastewater increased on maize crop. The roots development of black oats contributed to improve the soil physical quality and decreased the compaction on 0 to 15 cm, upper layer. There were an increases of K+, Cu and Zn contents, potential acidity and cation exchange capacity and decreases of Ca2+, Mg2+ and Fe contents, base saturation and soil pH. In this experiment, rates up to 200 m3ha-1 (except control) showed available results of nutrients; which did not cause deficiency on soil aeration, important to crops. Thus, it can be used as maize topdressing.