Different Patterns of Aggregate Stability in Burned and Restored Soils

Abstract

The merits of soil aggregate stability determination by rainfall simulator method were studied. This method is based on the supposition that in standard conditions aggregate breakdown is proportional to the kinetic energy of the rainfall applied. We compared three experiments using four different soils. Two of the experiments were in controlled conditions and the other at field conditions. In one of the laboratory experiments we applied sewage sludge to a degraded soil from a semiarid climate. In the other laboratory experiment a forest soil was heated to 200°C, 400°C and 600°C, and we studied the effect of heat and loss of organic matter in soil aggregation. In the third experiment, carried out in the field, we studied the response of two soils affected by forest fire in different intensities. Aggregate stability percentage and organic matter content of soils were determined to establish trends between these parameters. Aggregate stability in soils subjected to rainfall simulation was used as an indicator for potential degradation or restoration processes of the soils. In some burned soils positive and negative relationships were obtained between aggregate stability percentage and organic matter soil contents due to heat-aggregation processes. It showed that the aggregate stability percentage method based on disruptive energy of a rainfall simulator could not always be used as an index of degradation or restoration of soils or both.