AÇÃO DO SISTEMA RADICULAR DE PLANTAS NA FORMAÇÃO E ESTABILIZAÇÃO DE AGREGADOS DO SOLO

The objective of this study was to evaluate soil aggregate formation and stabilization as related to plant root development. During 1990 and 1991, two clayey soils - a dusky red latosol and a dark red podzolic - from Rio Grande do Sul State (Southern Brazil) were studied under the following conditions: wheat/soybean with conventional tillage; setaria grass (Setaria anceps L.); digitgrass (Digitaria decumbens L.); siratro (Macroptilium atropurpureum L. ); oats/corn with no-tillage and bare field. Root density was highly correlated with aggregate formation and stabilization. The high root density together with the conditions created by root development were probably responsible for the better aggregation which was observed in the soil under perennial grasses.