Recuperação de pastagens de Brachiaria decumbens Stapf.: aspectos técnicos e econômicos

Abstract

Pasture degradation is one of the principal problems of Brazilian animal husbandry. The experiment was carried out in an area of the Livestock farm of the School of Agronomy, Federal University of Bahia. The objectives were to evaluate the recuperation methods of degraded pasture of Brachiaria decumbens Stapf. and to determine the economic viability of the recuperation methods, in the Recôncavo Sul Region. The experiment was accomplished in a randomized block design in order to evaluate 8 methods of degraded pasture recuperation in 4 times of deferment (60, 90, 120 e 150 days after pasture fertilization), with 4 replications. The treatment effects were evaluated through the following variables: dry matter production, crude protein production in the natural matter, weed infestation end soil coverage. The dry matter production values showed that the degraded pasture recuperation methods (M5 and M6) with liming + NPK fertilization were greater than the others, but the ones with harrowing without fertilization did not have a good response. The presence of N influenced dry matter production. The methods with fertilization including N were greater concerning crude protein content at 60 days of deferment. However, at 90 days of deferment the method with NPK fertilization and harrowing was the only one to show crude protein contents adequate for animal nutrition. The weed percentage reduced while soil coverage increased, with the advance of the times of deferment, as compared to the values observed from the beginning of the work. These effects were least evident on recuperation methods with harrowing. Besides this work, it was done an economic study of the data in order to determine the economical viability of 8 methods of pasture recuperation on deterministics bases. The results were evaluated by tabulating the pasture recuperation costs per each method and the average dry matter productions obtained on 60, 90, 120 and 150 days of deferment. Based on 11 the costs of pasture rents it was employed the following performance indicators (profitability): gain cost relationship (GCR), economic payback (EPB), internal rate of return (IRR), and present net value (PNV). All the methods showed positive economic results, being the M5 method (mowing + liming + NPK fertilization) the one that achieved the best performance with PNV values of 3.144 on 10 % rates, IRR values of 15,5 %, GCR values of 1,01 and period for capital return of 29 months, having the best financial viability, least cost of opportunity and insurance in the return of invested capital.