Field moisture characteristics of two fersiallitic soils in Zimbabwe

Abstract. Little is known about the in situ hydrological properties of Zimbabwean soils. This paper describes the water retention and transmission properties of two agriculturally important Zimbabwean fersiallitic soils measured in situ by the instantaneous profile method. The first soil, typical of those used by small scale farmers, is a deep coarse grained granitic sand. The second is a silty clay loam derived from mafic rocks, typical of the red clays associated with Zimbabwe's commercial farming areas. The K ‐θ functions for each layer of the sand were very similar and the profile could be described by a single function, with permeability increasing with depth. In contrast, the silty clay loam could not be described by a single function, as permeability decreased with depth. However, in both soils water movement became negligible below a matric potential of—0.01 MPa; this is thought to be a more appropriate field approximation of the upper limit of plant available water than—0.033 MPa which is often used for tropical soils.