Australian soils blowing in the wind
Dust storms, dust hazes or the back paddock blowing, seem to be a part of life for many Australians. But dust is the ‘business end’ of wind erosion.
Australian dust can contain up to 35% organic material. Incredible considering on average Australia’s ancient soils have an organic component of less than 2%! How can this be? Winds cause larger soil particles to roll and bounce across the ground. The impact of these grains on the soil initiates movement of other particles. The effect of the wind is like a sieve, sorting the finest particles out of the soil, taking organic matter with it. The smaller the particles the higher and further they travel. Dust from South Australia is frequently tracked beyond the Eastern Australian coastline, and often to Antarctica.
Loss of these fine nutrient-rich organic components is a serious land degradation issue, so monitoring is essential. Dust can be measured remotely by stand-alone sensors and the data can inform when and where dust events are occurring enabling tactical decision-making by land managers. Strong and colleagues have initiated a community dust monitoring network “DustWatch” which provides hourly records on-line.
Generally, a minimum of 50% ground cover is necessary to prevent wind erosion. But vegetation is only part of the ground cover story.
In rangelands, a large proportion of soil surface ground cover is derived from micro-organisms in biological soil crusts (BSCs). Biological soil crusts are known to reduce the rates of wind erosion by protecting fine soil particles against the impact of bouncing grains.
The presence of biological soil crusts is a useful indicator of good land management practices. These biological soil crusts are also important to the sequestration of carbon. In collaboration with researchers from the UK and the US, Strong is exploring the secret lives of soil crusts. The findings of this research will provide a crucial link for land managers on how to maximise sustainable soil management solutions that conserve soil crusts, capture carbon and reduce the greater impacts of wind erosion.