Produção e valor nutricional de forrageiras sob adubação orgânica

Abstract

The aim of this study was to evaluate the yield, crude protein content and macronutrients concentration of winter and warm, chemical soil properties season forage crops under bovine manure fertilization in a Luvissolo Háplico órtico típico. The experiment was carried out at the Centro de Ciências Rurais da URCAMP, Bagé, RS, Brazil in two distinct seasons: ryegrass was cultivated during the winter and millet was cultivated during the summer. The experiment was conduced in a randomized block design, with five treatments and four replications. The size of each plot was 4m2 and the spacing between them was 0.5m, with a total area of 136.5m2. The treatments used were: (T1) no bovine manure vermicompost, only lime (control); (T2) bovine manure vermicompost (VB) at 25% of its total recommended rate by Manual de Adubação e Calagem do RS e SC (ROLAS) + lime; (T3) VB at 50% of Its total recommended rate by ROLAS + lime; (T4) VB at 100% of Its total recommended rate by ROLAS + lime; (T5) VB at 125% Its total recommended rate + lime. The variables analyzed were: green and dry biomass, crude protein content and macronutrients (N, P, K, Ca, Mg) of the aerial parts of the plants. Soil chemical analysis tests have also been performed before the experiment starts and after each crop cycle. The results were: the organic fertilization of forage crops is an excellent alternative for small farms; the use of bovine manure vermicompost at 125% of Its total recommended rate by ROLAS + lime increases considerably the variables: fresh and dry fitomass as well as the crude protein content of the aerial parts of the crops studied; foliar levels of N, P, K in the culture of ryegrass respond increasingly to the application of bovine manure vermicompost. The concentration of these nutrients decreased progressively with the aging of the plants in all treatments. In regards to the soil, it can be concluded that after the cultivation of ryegrass there was an improvement in quality thereof, except for the following variables: Mg, CTCpH7, Sum of Bases, effective CTC and P in T1, T2 and T3. After the cultivation of millet, It has been observed an increase in the levels of P, Mg, CTCpH7 and a decrease in the levels of K; The ryegrass crop is more responsive to organic fertilization than millet.