SOIL Compaction UNDER Different Sugarcane Management Systems.

In the sugarcane production system, soil preparation is one of the most important phases because the management operations performed during the installation of the crop will influence sugarcane yield over several years.  Intense machinery traffic occurring during crop renewal added to successive mechanical operations during crop development intensify even more the compaction of the soil of deep layers.  Knowing that sugarcane roots can reach depths of 5 m it becomes important to monitor soil compaction. Therefore, the present study had the objective of evaluating soil compaction under different soil preparation systems and crop spacings for sugarcane. Conventional (CON) and Minimum (MIN) tillage were combined with two spacings: Simple (S) of 1.5 m and Double (D) alternating 1.5 and 1.9 m, resulting treatments  CON-S, CON-D, MIN-S and MIN-D, added to a deep soil preparation with double spacing (DSP), with a total of five treatments Soil penetration was evaluated with a portable penetrometer that was compared to an electronic penetrometer.   Measurements were taken within cane lines to be sure to be in the region where most of the roots develop, at depths of 0-20, 20-40, 40-60, 60-80 cm. At the soil surface  (0-20 cm) and the deepest layer (60-80 cm) no significant differences were found among treatments. At the 20-40 cm layer, treatment PPF (0.29 MPa) presented lower penetration resistance in relation to CON-S and MIN-S (1.36 and 1.56 MPa, respectively). For the 40-60 cm layer the DSP (0.45 MPa) treatment showed his efficacy, once penetration resistance values were significantly lower in relation to all other treatments. Penetration resistance indexes were very promising for the deep soil preparation (DSP), where other assessments also proved its efficiency in comparison with other treatments.