RESPONSE OF THE GROUND LAYER COMMUNITY OF A CERRADO VEGETATION IN CENTRAL BRAZIL TO LIMING AND IRRIGATION

A split plot design with irrigation as the main plot treatment and liming as subplot treatment was utilized to determine the response of the ground layer community of a cerrado vegetation on a dystrophic dark red latosol (Haplustox) in central Brazil to liming and irrigation. Aerial live biomass of the grasses and nongrasses of the ground layer and their nutrient concentrations were determined over a period of 18 months. As liming rate increased from 0 to 8.4 t ha(-1) the soil pH increased from 5.2 to 5.8. The availability of Ca increased from 0.24 to 6.91 cmol (+) kg(-1) dry soil and that of Mg from 0.10 to 0.17 cmol (+)kg(-1) dry soil. Liming decreased the exchangeable Al from 0.66 to 0.24 cmol (+) kg(-1) dry soil. There was an increase of up to 70% in the biomass concentration of Ca in grasses and 87% in nongrasses as a result of liming up to 8.4 t ha(-1). Concentrations of Mn decreased by 37% in grasses and by 33% in nongrasses. However, liming did not result in any increase in the primary production of either grasses or nongrasses. Irrigation during the dry season did not alter soil pH, nutrient availability in the soil or foliar concentrations of nutrients in grasses and nongrasses. Irrigation during the dry season increased the live aerial biomass of grasses by an average of 41% over the experimental period but not that of the nongrasses.