Soil properties: soil erosion by wind
Indicator Status: For Advice
Department of the Environment and Heritage
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Why do we need to monitor soil erosion by wind?
Soil erosion by wind is a natural process but its occurrence and severity has increased with agricultural expansion and pastoralism. Although not as widespread as water erosion, the effects of soil erosion by wind are often more dramatic. The quantities of soil moved per hour across the edge of 1 ha by wind erosion can be of the same order as that moved by water erosion in 1 year (White 1997). Wind erosion not only removes soil but selectively the most nutrient rich fractions of the soil.
Detrimental effects following wind erosion include:
- loss of soil;
- loss of nutrients and organic matter;
- formation of scalds (areas of bare, hardened ground that do not easily soak up water);
- reduced infiltration of water;
- significant damage to young crops and pastures by sandblasting, burial or scouring; and
- burying of on- and off-farm infrastructure (i.e. roads, railway lines, fences and water supply channels).
Considerable impact away from the site of soil loss can occur through long-distance transport of dust affecting human health, reducing visibility and disrupting electricity supplies (Leys 2003). For South Australia alone, the off-site impacts of wind erosion may be costing $23 million annually, largely due to impacts on human health (asthma and general respiratory problems) (Williams & Young 1999).
Wind erosion in Australia is confined mainly to the low rainfall areas. For human-induced or accelerated wind erosion, this tends to be the semi-arid zone (300 - 500 mm rainfall) (McTainsh et al. 2001); however, this zone expands if failures in seasonal rainfall occur such as in 1982, 1994 and 2002. Widespread droughts challenge traditional agricultural systems because they fail to maintain adequate surface cover and soil aggregation levels. More sustainable agricultural systems have demonstrated that erosion can be controlled during the recent 2002 drought.
The annual frequency of dust storms across Australia during the twentieth century has notably decreased since the 1970s (Hamblin 2001). This has been attributed to the improved control of rabbits (through myxomatosis and more recently the rabbit calici virus); the spread of woody weeds and Acacia nilotica; and the adoption of conservation tillage. Dust storms are still a serious problem where cropping practices do not include retention of vegetative cover and minimum tillage methods. More than half of Australia's cropping lands are at risk on a seasonal basis, with the sandier 'mallee' lands of southern Australia particularly vulnerable (Hamblin & Williams 1996).
Dust storms are natural geomorphic processes, and while agriculture and other land uses may have accelerated their frequency and intensity, some agricultural systems can also mitigate wind erosion during drought. The aim of wind erosion control is to implement management practices that will avoid erosion and not, as in the past, repair erosion after the event.
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