Trees and Animal Production in a Silvipastoral System with Black Wattle (Acacia mearnsii)

Abstract

A silvopastoral study consisting of black wattle (Acacia mearnsii De Wild) and tropical perennial grasses was developed at the Fepagro Research Unity in Tupanciretã, RS, in collaboration with Seta Group, from October 1995 until May 2003, with the objective of evaluating trees and animal (beef cattle) performances. The experiment was a bifactorial completely randomized design (forage specie and arboreal density) with two replications. The forage species assessed (FS) were anonni grass (Eragrostis plana), signal grass (Brachiaria brizantha) and gatton panic (Panicum maximum cv. Gatton) in the first four years, and gatton panic, aruana grass (Panicum maximum cv. Aruana) and pangola grass (Digitaria diversinervis) in the remaining years. Trees densities (TD) tested were of 1,667; 1,000; 833 and 500 trees.ha-1. The highest wood production was observed at TD 1,667 trees.ha-1, although it was not different from that for 1,000 trees.ha-1 from the fifth year on. The animal production under arboreal density 833 and 500 trees.ha-1 was 229 e 223 kg.ha-1 of liveweight gain, respectively. At seven years of cultivation of black wattle the wood production were 166; 143; 86 and 51 m3/ha-1, respectively, under arboreal density of 1,667; 1,000; 833 and 500 trees.ha-1. To achieve of an equilibrium between trees and animal production, this study showed that silvopastoral systems with 1,000 and 833 trees.ha-1 are viable alternatives for farmers.