Protect paddocks from wind erosion
Landholders who have paddocks with low levels of ground cover have been encouraged to take action sooner rather than later to minimise the impact of wind erosion.
There have already been reports from across the grainbelt of wind erosion, as a result of below average winter rainfall.
Despite recent rainfall over parts of the grainbelt, the prospect of below average rainfall in coming months meant there would be a high risk of wind erosion over summer and beyond.
While there is little landholders can do to protect paddocks that are ‘already blowing’, there are options to reduce wind erosion risk in paddocks with lighter soil types.
Avoid disturbing at risk soils
Keeping the soil stable and anchored to prevent topsoil from being blown away will reduce damage in this year and prevent yield reductions for future crops and pastures.
Keeping machinery, including vehicles, off paddocks and removing stock will prevent surface soil from becoming detached.
Livestock considerations
Livestock feed and water management will be critical in coming months, with many growers already hand feeding stock.
Producers will have to weigh up the cost of supplementary feeding against the increased risk of erosion and its impact on future paddock potential.
Department of Agriculture and Food, Western Australia research has shown ground cover of 50% or more by the beginning of autumn is required to minimise the impact of wind erosion, as well as water erosion when it rains.
The department encourages producers to plan flock or herd management for the next 12 months, as the spring forecast for most of the grainbelt is for below average rainfall.
Producers will need to be mindful of stocking rates and feed budgeting to manage paddock grazing pressures and ensure there is at least 600 kilograms per hectare of dry matter on pasture paddocks.
Options to keep stock off paddocks include feeding them in confined paddocks or feedlotting, while growers could also consider the cost-benefit of agisting or selling stock before both paddocks and stock lose condition.
Cropping considerations
Growers considering reseeding paddocks to provide ground cover over coming months or turning cropped paddocks over to feed should also be aware of the erosion risk, as well as any herbicide residues.
The decision to reseed should take into account the local season forecast and paddock conditions.
Before reseeding, growers are encouraged to inspect sown paddocks for any viable seed that may germinate with the next rain. Wetting up small patches to check for germination may save a lot of expense.
It is important to note that canola crops sown with atrazine or propyzamide have withholding periods that are longer than cereals, so it is best to check before opening the gate to stock.
Weed management
Weed management also poses a dilemma.
While weeds will help to stabilise the soil and cutting the cost of herbicides may seem an attractive option, the long term cost of not spraying out weeds could be more detrimental. It would be best for landholders to discuss their options with their local agronomist.
Spreading clay or gravel
Small bare areas, such as sheep camps, gateways and around watering points, in otherwise well covered areas can also lead to severe blowouts.
These areas can be protected by binding spray, claying or laying gravel, old hay or straw to give full cover.
For larger areas of at risk sandy soils one of the most effective but also a more expensive option is to spread clay-rich subsoil or gravel or gravelly loam using a heavy duty multi-spreader.
The subsoil needs a clay content of 30% or more. Rates of 50-75t/ha are often adequate to prevent erosion but rates of 75-120t/ha or more may have lasting benefits to reduce topsoil water repellence, depending on the quality of the subsoil used.
At these rates there is still minimal need for deep incorporation of the clay leading into next season and the action of the seeder or a scarifier would likely be adequate.
Spreading the material through a multi-spreader is the ideal option for evenness of spread, cover and speed but other more intensive approaches could be used for smaller areas.
At the lighter rates of clay it would still be important not to traffic the soil too much – until it is wet and a cover crop can be seeded.
This approach is expensive but may still be helpful to target or prevent patches at risk of blow-out which could be an ongoing problem for many years to come and difficult (and very expensive) to rehabilitate.
When protecting sands from wind erosion it will often be necessary to prioritise areas. Identify and target bare sands that are exposed and at risk of becoming a blowout.
Where options are limited, avoid disturbing the soil surface and monitor the site after strong wind events.
Long term investments to mitigate wind erosion include planting trees as windbreaks to reduce wind speed and applying clay subsoil or loamy gravel to at-risk areas.
For more information contact David Bicknell, Senior Development Officer, Narrogin, +61 (0)8 9881 0228.