Impactos das operações mecanizadas da colheita florestal sobre a estrutura dos horizontes BA e Bt de um argissolo amarelo

Abstract

The main source of soil structure degradation in forestry is the traffic of machines, which can cause soil compaction. Os objetivos deste estudo foram: a) gerar os modelos de capacidade de suporte de carga para os horizontes BA e Bt de um Argissolo Amarelo (PA) e b) determinar através do uso desses modelos a suscetibilidade à compactação dos horizontes BA e Bt e a compactação promovida pelas operações de colheita florestal. The objectives of this study were: a) to generate the load bearing capacity models for the BA and Bt horizons of a Yellow Argisol (PA) and b) to determine the susceptibility to compaction of the BA and Bt horizons and the compaction promoted by the forest harvest operations. This study was conducted in the areas of Suzano Papel e Celulose. Two forest harvest modes were evaluated: 1) Harvester and Forwarder and 2) Feller Buncher and Skidder. The sampling was carried out at the top of the BA and Bt horizons and consisted of: a) 15 undisturbed soil samples to obtain the load bearing capacity models, b) 15 undisturbed soil samples by horizons and machine for the Harvester and Feller Buncher c) 3 undisturbed soil samples by horizon and for each traffic intensity of the Forwarder and Skidder for the condition of traffic outside of the residue and d) 2 undisturbed soil samples by horizon for each traffic intensity of the Forwarder for the condition of traffic on the residue. These samples were used in the uniaxial compressio n test. The Bt horizon showed higher load bearing capacity than the BA horizon, being therefore more resistant to compaction. The operations realized with the Feller Buncher promoted greater compaction than those performed with the Harvester in both horizons. The operations performed with the Forwarder over the residue promoted smaller compaction than when the traffic was carried outside of the residue and the Skidder.