Mechanisms of Soil Erosion in Andic Soils of the Canary Islands

摘要

The aim of this paper is to assess the mechanisms of water erosion in andic soils, by two tests, which in a certain way simulate the two principal mechanisms of aggregate destruction in the process of water erosion: water dispersion and raindrops impact and compare it with the aggregation observed in material dettached by interrill erosion (sediments) in experimental plots with natural rain. In accordance with the obtained results, the erosive process in these soils seems to come about through a picking off of surface material of larger aggregates, due to the impact of raindrops. The intensity of pull off and fragment size from larger aggregates, depends on the cinetic energy of the drops (rain intensity), but the size generally ranges between 0.2 and 0.5 mm. Therefore interrill erosion initially proceeds by a washing down of smaller aggregates ( < 0.5 mm) (of less bulk density than larger aggregates 0.4 MgM~(-3) against 0.9 MgM~(-3)), enrichening the soil in larger sized aggregates that on being fragmented by picking off of raindrops, supply new material for washing down by interrill erosion.