Water retention capacity in soils of the Serra do Mar, SP

Abstract

A comparative study of the physical, mineralogical and microstructural properties and the soil-water retention curves of representative soil horizons of two weathering profiles (dystrophic Haplic Cambisols) of the Serra do Mar are presented here. The soil-water retention curves were obtained using three methods: suction plate (for suctions from 1 to 30 kPa); chamber of pressure (for suctions from 50 to 400 kPa), and filter paper (for suctions above 400 kPa). In general, the soils showed relative mineralogical homogeneity and a significant microstructural and textural heterogeneity. This heterogeneity directly affects the shape of the soil-water retention curves obtained for most soils, and may also (positively or negatively) influence the behavior of the hydraulic conductivity. In practice, changes in the hydraulic conductivity of soil layers will greatly influence the rainwater infiltration capacity, and hence the factor of safety or stability of the slopes in areas at risk. It is important to emphasize that the water retention behavior is not exclusively related to the mineralogical and textural characteristics of the soil, but also to microstructural features of the soil, such as soil macro and micropore distribution.