Variation of soils erodibility according to physico-chemical and biogeographic parameters in Allal Al Fassi watershed, Middle Atlas, Morocco.

Abstract

In order to the conservation of soil resources and the preservation of water and biodiversity, the study of the variation of soil erodibility according to physico-chemical and biogeographical parameters in Allal Al Fassi watershed is of great importance. The measurement of soil erodibility according to the Wischmeier and Smith model requiring a series of physico-chemical analyses of several intrinsic soil parameters (texture, structure, permeability, organic matter content, etc.) is performed on 9 transects with 150 samples. The first, the results are combined with the biogeographical parameters of the soils (slope, pedology, lithology and land use) and then are submitted to a multivariate statistical analysis, were able to highlight both the qualitative and quantitative characteristics of the watershed. Soil erodibility in Allal Al Fassi watershed is moderately strong, ranging from 0.05 to 0.38 t. ha. h. ha^-1MJ^-1.m^-1. Statistical analysis shows that soil erodibility (K) is closely related to texture, organic matter content and especially land use. It is more important in farmland, unlike soils occupied by matorral. Soils become more erodible when the silty fraction dominates and clay and organic matter levels decrease.