Propriedades físicas do solo e crescimento de eucalipto implantado em diferentes métodos de preparo do solo

Abstract

The objective of this study was to determine changes in the physical properties of an Alfisol and in the growth of Eucalyptus grandis, established under different soil tillage methods, after 6 years. The experiment was conducted at the State Foundation for Agricultural Research in Santa Maria, Rio Grande do Sul. The experimental design used was randomized blocks with three replications and four treatments: manual hoeing, chisel plow, chisel plow plus harrowing and rotary hoe. Undisturbed soil samples were collected from depths of 0-0.10; 0.10-0.20; 0.20-0.30 and 0.30-0.40 m before and seventy-two months after the soil preparation in order to determine the macro porosity, micro porosity, total porosity and bulk density. The size distribution of water stable aggregates and the organic matter content of the soil were determined in the 0-0.05 m layer. Eucalyptus growth was evaluated at seventy-four months old by measuring height, diameter and survival of trees. Six years after soil preparation there were no significant differences between treatments for the soil physical properties and eucalyptus growth. However, there was a negative effect from manual hoeing on the trees survival. In the same period an improvement of soil physical properties by reducing density and increasing porosity in the surface layer was observed, highlighting the influence of soil and root system organic matter as well as litter from trees.