Applications of the resistance curve in the control of the physical quality of soils under grass

The degradation of the physical quality of soils has been associated with t he soil compaction caused by animal trampling. The soil resistance to penet ration (SRP) is a soil physical parameter used to assess the soil compactio n degree. However, SRP varies with soil moisture (theta) and bulk density ( D-b). The objective of this research was to quantify the soil resistance cu rve and use it to evaluate the physical quality of a soil under short durat ion grazing system of elephant grass. The soil resistance curve was measure d using forty-eight undisturbed cores taken at the 0-10 cm depth of a Kandi udalfic Eutrudox used with elephant grass in intensive system of exploratio n. The results indicated a negative correlation among SRP and theta as well as a positive correlation between SRP and D-b. Predictions indicated that at soil matric potential equal to -0.01 Mfa the SRP did not reach critical values to root growth. Nevertheless, at the soil matric potential equal to -0.3 MPa, the SRP reached limiting values in the whole area. For the manage ment system and the studied species, the results suggest that soil resistan ce curve may be used to guide soil management practices for maintaining a g ood soil physical quality for grass growth.