EFFECT OF HARVEST RESIDUES MANAGEMENT, SOIL TILLAGE AND FERTILIZATION ON EUCALYPTUS PRODUCTIVITY

Forestry companies have become increasingly concerned about the adoption of practices based on the conservation of soil and water. Thus, this study aimed to assess the impact of crop residue management, tillage and the use of industrial wastes on soil fertility and productivity of eucalyptus. The experiment started after clear-cutting of a commercial plantation of Eucalyptus grandis and the harvest residues were managed differently (removal of all residues; removal of bark and branches with diameter >3.0 cm; and maintenance of all residues on the soil surface). Thereafter, the soil was tilled (with a subsoiler with one or three shanks), industrial waste was applied (pulp residue and ash) on the soil surface and seedlings of Eucalyptus grandis x E. urophylla planted. A randomized block design was used with eight treatments and four replications. The treatments consisted of combinations of different types of crop residue management, soil tillage and application of industrial waste. Each experimental plot consisted of five rows each with 19 trees. Eighty-three months after planting, the DBH (diameter at breast height) and tree height were measured to calculate the wood volume. Fertilization and maintenance of forestry crop residues raised the levels of exchangeable Ca2+ and Mg2+ in the soil. The maintenance of all plant residues in the field after harvesting induced an increase of 71.7 m(3) ha(-1) compared to the treatment with removal of all waste. There was no difference between the subsoiler tillage systems with one or three shanks on the wood volume. Highest timber volumes were obtained in the treatments in which the largest quantities of cellulose and ash residue were applied while part of the plant waste was left on the soil surface after harvest. The application of wood and ash residues maintained and/or increased Eucalyptus productivity.