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WA growers urged to protect topsoil: DPIRD

Grain Central, November 22, 2023

Wind erosion on stubble paddock during cyclone. Source: DPIRD

STRATEGIC paddock management over summer and autumn will be crucial to protect valuable topsoil
and crops in 2024, Western Australia’s Department of Primary Industries and Regional Development said in a statement released this week.

Satellite imagery shows properties in the WA’s north-east grainbelt could be particularly susceptible this
year, with low levels of pasture coverage in some areas.

Commissioner of Soil and Land Conservation Melanie Strawbridge has called on landholders to
maintain stubble and manage vulnerable land carefully to prevent soil erosion.

“A short growing season, below-average rainfall and an early start to the 2023 harvest all point to
conditions where cover is inadequate to prevent erosion,” Dr Strawbridge said.

“Healthy soil is a property owners’ primary asset and after years of managing and improving soil, now is the time to ensure it remains in place.”

DPIRD research scientist Justin Laycock said planning was key to maintain at least 50 percent
groundcover through to the start of the 2024 growing season to stop soil from blowing away.

“Keeping more than 50pc vegetative cover will allow landholders to manage properties without fear of your soil blowing away,” Mr Laycock said.

“For example, dry seeding next year will be less risky in a paddock with adequate groundcover
than one with less cover, while stubble retention allows summer weeds to be eliminated rather than
maintained to protect the soil from strong erosive winds.”

A stubble of 1.5 tonnes per hectare from a wheat crop yielding 750kg/ha should provide adequate cover, while farmers can also lay the stubble over to estimate the proportion of bare soil to determine the percentage of coverage.

Options to reduce the risk of soil erosion include keeping stock off paddocks with low cover by
confinement feeding, agisting or selling stock before paddocks and stock lose condition.

DPIRD said it was important to limit vehicle movements in susceptible paddocks, and protect small bare areas such as sheep camps, laneways and those around gateways that could lead to larger soil blowouts by applying clay, gravel, straw or a binding spray.

There are additional benefits from retaining stubble, including improved rainfall infiltration, reduced
soil-water loss, improved soil-organic matter and soil structure, as well as protecting seedlings from
sand blasting in the new season.

Mr Laycock said landholders considering grazing stubbles would be wise to examine the longer-term impact on paddocks carefully.

“Sheep only eat about 6pc of stubbles, and with more efficient harvesting techniques and weed control, stubble paddocks contain less nutritional value these days.”

“We recommend managing grazing to retain at least 600kg/ha of dry matter on pasture paddocks to prevent soil erosion.

“Feed budgeting will be essential to help manage pasture cover and livestock health.”

Landholders are also encouraged to delay soil amelioration activities until the soil is moist in order to reduce soil disturbance and erosion risk.

In severe cases, the Commissioner can issue a Soil Conservation Notice to direct a landholder to
manage existing or prevent further erosion.

DPIRD earlier this year published timely advice on how to manage stubble and wind erosion.

 

Source: DPIRD

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