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 the soil compaction caused by animal trampling. The soil resistance to penetration (SRP) is a soil physical parameter used to assess the soil compaction degree. However, SRP varies with soil moisture (theta) and bulk density (D-b). The objective of this research was to quantify the soil resistance curve and use it to evaluate the physical quality of a soil under short duration grazing system of elephant grass. The soil resistance curve was measured using forty-eight undisturbed cores taken at the 0-10 cm depth of a Kandiudalfic Eutrudox used with elephant grass in intensive system of exploration. 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 management system and the studied species, the results suggest that soil resistance curve may be used to guide soil management practices for maintaining a good soil physical quality for grass growth.