In an effort to be optimistic about the rainfall this winter, we are diving into the issue of water erosion. While water erosion is no shallow topic and is far from ideal for landholders, we would love to see enough water around the Northern Agricultural Region to make this a significant topic on the lips of landholders everywhere.
Water erosion is the removal of soil by water and transportation of the eroded materials away from the point of removal. This occurs when rain hits the soil surface and displaces soil particles or when water flows over the land taking soil particles with it.
Although the movement of sediment is a natural process, the cultivation of land for agriculture accelerates the impacts of water erosion. This can cause a loss of topsoil, reduced crop yields, damage to infrastructure, weed dispersal, eutrophication (algal blooms) and silting of dams and natural waterways. It can also cause downstream flooding and sedimentation.
According to the Western Australia Department of Primary Industries and Regional Development the average annual direct cost of water erosion to dryland farming in Western Australia is estimated to be $10 million, but the costs are much higher in years when severe summer storms occur.
But don’t drown in fear, there are a number of strategies that can help to mitigate water erosion.
- Maintain live vegetation cover- It is recommended to maintain 50–70% live vegetation ground cover to protect the soil surface from surface water flows.
- Restrict livestock access to susceptible areas- Reduction in stocking rates or the removal of livestock from areas likely to erode is an essential step to mitigate erosion. Heavy grazing removes groundcover and loosen the soil surface.
- Manage firebreaks- If possible, the use of herbicides for firebreaks comparative to ploughing is preferable. Leaving the soil undisturbed (lower erodibility) is especially important on steep slopes.
- Maintain stable soil condition- Maintaining good soil structure is essential. By managing stock rates, applying gypsum to soils susceptible to dispersion, or improving the soil organic matter content (e.g. through deep-rooted perennials).
- Install surface water earthworks- Investing in some surface earthworks can control erosion by intercepting, diverting or slowing run-off rather than permitting it to flow uninterrupted down a slope.
If you are concerned about water erosion on your farm, or would like a bit more information, please get in touch with our Regional Agriculture Landcare Facilitators.
Annabelle Garratt (E) Annabelle.Garratt@nacc.com.au (P) 0448 986 879
Lizzie King (E) Lizzie.King@nacc.com.au (P) 0447 361 335