Wind Erosion in Western Queensland Australia

Chapter 4 –Modelling Soil Erodibility DynamicsConsiderable research has been conducted examining soil properties affecting wind erosion(reviewed in Chapter 2). The piecemeal nature of much of the research, however, has meantthat it is difficult to integrate research findings to build models of ‘big picture’ processes.This characteristic is a result of the complex response of soil aggregation and crust dynamicsto external drivers, and difficulties associated with extracting meaningful data on soilclimate-managementinteractions (Merrill et al., 1997). In particular this affects our ability toparameterise models to predict temporal changes in soil erodibility.Table 4.1 summarises a selection of studies examining: a) soil aggregation changes inresponse to climate and management variability, b) soil crust disturbance effects on soilerodibility; and c) soil crust responses to trampling disturbance by livestock. Studiesexamining aeolian abrasion of crusts have not been included as these pertain to the process oferosion and dust emission as opposed to the immediate erodibility of a soil surface. Bothqualitative and quantitative approaches have been used to examine temporal changes in soilerodibility, and passive monitoring and active manipulation of sites have been used todetermine relationships between control and response variables.Historically, soil aggregation responses to climate variability have been studied in cultivatedregions where the economic and social consequences of severe wind erosion are wellrecognised. The majority of these studies have been conducted in North America and havefocused on monitoring seasonal responses of soils to freeze-thaw cycles and under cultivation(Bisal and Ferguson, 1968; Merrill et al., 1999; Bullock et al., 2001). Standard methods forreporting on soil aggregation conditions, for example through aggregate size distributions,aggregate stability or the soil erodible fraction, have been adopted in many of these studies.This means that there is potential for comparing results between studies on different soil,management or climate conditions and parameterising a generalised model of soil erodibilityresponse to climate, like that presented here. Few studies have used regression analyses tointegrate relationships between factors controlling soil aggregation in empirical models (e.g.Zobeck and Popham, 1990; Fryrear et al., 1994; Lόpez et al., 2007).122