AGGREGATE STABILITY OF AN ULTISOL IN REGIONS OF THE BRAZILIAN AMAZON

The aggregate stability is essential for water infiltration, soil aeration and root penetration resistance, impacting water infiltration, moisture retention, soil aeration and root penetration resistance. Inadequate agricultural practices can limit root growth, cause compaction, reduce water infiltration and increase water erosion. This study evaluated the stability of aggregates of an Ultisol in the Amazon, including different ecosystems: natural forest, natural savannah, forest converted to pasture and savannah converted to pasture. Three soil depths were analyzed at 0.00 to 0.10 m, 0.10 to 0.20 m and 0.20 to 0.40 m. The properties evaluated included aggregate classes, geometric mean diameter, weighted mean diameter, dispersed clay, degree of clay flocculation, sensitivity index and organic matter. The results showed that the conversion of natural environments to pasture did not significantly affect aggregate stability indices, suggesting that proper pasture management can maintain the structural quality of the soil.