Wind Erosion in Western Queensland Australia

Chapter 4 –Modelling Soil Erodibility Dynamics0.84 mm diameter) on the soil surface (Chepil, 1950a). The soil ASD is a function of thelevel of soil aggregation and physical or biological crusting (Zobeck, 1991). These propertiesare determined by soil texture, chemistry, organic matter content, and dynamic factors suchas climate (e.g. rainfall, temperature) and land management (Figure 4.1). Soil moisture is animportant control on soil erodibility and is a transient factor that may be consideredindependent of the soil inherent wind erodibility which is primarily determined by the ASD(Merrill et al., 1997).Figure 4.1 Flow chart illustrating the relationships between soil erodibility controls within alandscape. Grey boxes represent environmental conditions and processes that determine soil surfaceconditions and the impact of disturbance mechanisms on the availability of loose erodible materialThe susceptibility of a land surface to wind erosion is highly sensitive to changes in soilerodibility. This sensitivity is most evident when crusted soil surfaces are disturbed bycultivation or trampling by livestock. Belnap and Gillette (1997), for example, reported a 73-92% decrease in the threshold friction velocity (u *t ) required for grain mobilisation onmoderately disturbed sandy soils. Numerous studies have reported similar responses for arange of soils and types of surface disturbance (e.g. Williams et al., 1995; Leys and Eldridge,100