EFFECT OF TWO GRAZING INTENSITIES ON THE HYDRAULIC PROPERTIES OF AN ANDISOL (DURIC HAPLUDAND)

Abstract

To evaluate the grazing effect on soil hydraulic properties, structural properties of an Andisol under pasture with two grazing intensities were compared. The plots were sown in March 2006 with Lolium perenne cv. Arrow mixed with Trifolium repens cvs. Will and Huia. Before the first grazing, carried out in November 2006, the height of the pasture was homogenised by cutting once. The grazing frequency depended on the numbers of leaves of Lolium perenne cv. Arrow. The cows were removed from the plots when the height of the residue reached 5 or 8 cm (treatments). In March 2007 undisturbed soil samples were collected. The water retention curve, air permeability and saturated hydraulic conductivity were measured and the pore-size distribution, air-filled porosity, pore-continuity indexes and blocked porosities were calculated.

The results did not show significant differences for any of the soil properties, mainly due to the excellent physical qualities of the Andisol and the season when the samples were collected (lower rainfall and water content in the soil, therefore, greater bearing capacity). Consequently, the Andisol, Serie Valdivia is able to sustain a high grazing intensity during the spring-summer season, without a deterioration of its structural properties and pore functions.