LEAST LIMITING WATER RANGE AND SOIL COMPACTATION AS RELATED TO INTERCROPPED MAIZE AND BRACHIARIA

Intercropping of a forage and main grain crop ensures forage production in the autumn-winter, and straw for mulching in the no-tillage system. The contribution of dry root matter in the soil profile allows the improvement of soil structural quality. The objective of this research was to evaluate changes in soil physical and physico-hydric properties with the cultivation of maize grown alone and intercropped with Brachiaria brizantha. The study was carried out on the Experimental Farm Lageado (UNESP, Botucatu-SP) in the growing seasons 2002/2003 and 2003/2004. Undisturbed soil was sampled from the layers 0-20 and 20-40 cm by volumetric rings in plots growing maize and left fallow between harvest and in plots intercropped with maize and B. brizantha in the row, where the grass was maintained for grazing after maize harvest. The least limiting water range (LLWR) of these samples was evaluated, based on curves of penetration resistance and water retention in soil samples with different bulk densities. Maize grown alone is sufficient to improve the physical and structural characteristics of the soil in the 0-20 cm layer. Brachiaria intercropped with maize for two years improves the soil physical and structural properties in the layer 20-40 cm as well, reducing penetration resistance and increasing bulk density.