Limiting Water Content for Compaction Induced by Mechanized Operations in the Soil with Oil Palm in the Eastern Amazon

Oil palm is a commodity and the establishment of plantations and management are carried out using mechanized operations, which induce management zones with impacts on the physical properties of the soil. The objective of this work was to estimate the range of water content limiting the compaction process induced by mechanized operations. Sampling considered the following oil palm management zones: crest, machine traffic line, and planting row in three crops at depths 0-0.20, 0.20-0.40, and 0.40-0.60 m. The parameters of the van Genuchten equation (& theta;s, & theta;r, & alpha;, n) were used to estimate the water contents at the wet, dry, and optimum limit for tillage, and the range of water contents for tillage (& UDelta;& theta;Ranger). We determined the critical moisture for soil compaction, porosity, bulk density, and organic carbon. A difference was found between the management zones, especially in surface depth. In general, the highest water content limiting for tillage occurred in the planting line and the lowest in the traffic zone. Multiple regressions showed the influence of organic carbon and soil density on & UDelta;& theta;Ranger. In Addition, the temporal variation of soil moisture influenced the production of fresh fruit bunches, particularly in older plantations. The soils were trafficked above the wet tillage limit and critical compaction limit in the months of highest rainfall, showing the importance of & UDelta;& theta;Ranger in the planning of mechanized operations, seeking more sustainable management of oil palm.