CTF systems can reduce water erosion

And that was underlined by Department of Primary Industries and Regional Development (DPIRD) development officer Bindi Isbister at the national Controlled Traffic Farming (CTF) conference in WA last week.

She said the importance of surface water management to reduce the risk of water erosion associated with controlled traffic farming (CTF), was highlighted throughout the Wheatbelt earlier this year with widespread flooding due to unseasonably heavy rain.

Ms Isbister told the conference that surface water management planning was essential to prevent water flow from becoming concentrated.

“The regular orientation of furrows and wheel tracks can act as mini drainage systems, causing concentration of water that can initiate erosion,” Ms Isbister said.

“It is important to plan machinery run-lines and undertake wheel track maintenance to fill in sunken wheel tracks to minimise this risk.”

Department research has shown that paddocks sown to an up-and-downhill orientation enables surface water to drain uniformly down the slope, reducing the risk of furrow overflows and erosion.

Ms Isbister said other surface water management structures may be required to direct water safely, depending on the property’s soil type, landscape characteristics and paddock designs.

“The slope of the land, length of run, catchment area and soil type all contribute to the speed of the water flowing down-slope and its erosive potential,” she said.

“If the slope of the land is greater than one per cent, surface water management may be required and this will also assist with reducing water-logging or inundation in higher rainfall areas.

“Long runs that are often the most efficient for machinery operations may need to be broken up with surface water management structures.

“The optimum length of run and bank spacing will depend on soil type and slope gradients.”

Mitigation options include building broad-based banks to allow machinery to drive over the bank and through the drain, for slopes with gradients of between two and six per cent, lowering existing banks, establishing grassed waterways or catch-drains along access tracks to safely dispose of water.

Maintaining good stubble cover is another essential measure.

Ms Isbister said it was important to link up waterways between paddocks and farms, to dispose of excess water safely and reduce the severity of damage caused by flood events.

“It is also critical to prevent water shedding from uncultivated areas, such as rocky outcrops and roads, to avoid excess water concentrating in wheel tracks, which are unable to channel large volumes of water,” she said.

A range of materials are available to assist landholders to develop a surface water management plan, including aerial photographs, soil type maps and topographic data, yield maps and satellite imagery.

Some of this data can be accessed for free from the department’s website – agric.wa.gov.au by searching for ‘maps and data’, while more information on CTF can be found by searching for ‘controlled traffic farming system’.

The other issue was the maintenance of wheel tracks.

“There are now a few machines out there to help with track maintenance,” Ms Isbister said.

“There are renovators and speed tillers on the market and wheel track maintenance should be part of your CTF plnning because wheels trcks will get deeper.”

The department is continuing its CTF research, with the support of the Grains Research and Development Corporation.

Department of Primary Industries and Regional Development (DRID) development officer Bindi Isbister (blue jacket) talks with farmers about water management in CTF systems.

Water erosion is a real issue in controlled traffic farming systems unless surface water planning strategies are employed. This CTF paddock was gauged out during February rains this year.