AGGREGATES STABILITY AND RESISTANCE IN DA RK-RED LATOSOL (OXISOL) UNDER CORN GREEN MANURE SUCCESSION

Latosols (oxisols) under cerrado vegetation in their natural condition present, in general, high structural stability due mainly to the perf ormance of aluminum and iron oxides and organic matter. In the Cerrado region, however, the practice of burning cultural residues and the ex cessive use of harrow during soil preparation is very common, mainly t he plowing harrow, which pulverizes the soil with consequent weakness and destruction of soil structure. This study aimed to evaluate the re sistance of aggregates of a cerrado phase, clayey texture, Dark-Red La tosol (Oxisol) to simulated raindrop impact as well as the geometrical average diameter of aggregates of this soil under different green man ure-corn succession systems and under native cerrado. The tested green manure species were Crotalaria juncea, Cajanus cajan, Mucuna aterrima , Brachiaria ruziziensis and Canavalia ensiformis, cultivated in rotat ion with corn (cv. Pioneer 3072), during two years. The native cerrado presented larger and more stable aggregates, and it was necessary hig her kinetic energy for disrupting them. In the green manure systems, b rachiaria showed higher aggregation action than the leguminous species . The simulated raindrop impact method presented good performance, lea ding to better distinction among the treatments in relation to the agg regates stability method.