CTF and cultivation a ripper combo in eastern wheatbelt
GroundCover™ Issue: 115 | Author: Melissa Williams
Controlled-traffic farming (CTF) is generally regarded as the next major advance following the no-tillage development through the 1990s, to generate genuine yield increases and productivity gains in Western Australia’s cropping systems.
In the central wheatbelt researchers, agronomists and growers are seeing crop yield responses of 0.5 to 1 tonne per hectare where CTF is being used in conjunction with deep-ripping on compacted sands.
Results are especially noticeable when growing season rainfall is below average – as was experienced in 2014.
Department of Agriculture and Food, WA (DAFWA) officers Dr Paul Blackwell and Bindi Isbister say global research shows that where CTF is being used to help protect investments in deep-ripping or other mechanical amelioration tactics for compacted soils (such as inversion ploughing, rotary spading, delving and deep working seeding points) the benefits can last for many years.
“Without CTF, the benefits of these tillage systems to alleviate compaction might only last for a season or two,” Dr Blackwell says.
Data collected through GRDC surveys and the Australian Bureau of Statistics in recent years indicates that less than 20 per cent of Australian growers have adopted CTF and its permanent wheel-track system that confines load-bearing machinery to specific areas.
Dr Blackwell says introducing CTF with mechanical deep soil tillage can reduce compaction, improve soil health and cut crop input costs to help offset the capital costs of these systems.
He says research in WA has shown CTF can deliver about 10 per cent higher crop yields, less screenings in cereals and more oil in canola than uncontrolled/conventional traffic systems.
DAFWA-Liebe Group trials at Buntine are also finding wheat yield gains of up to 15 to 42 per cent – depending on the season – are possible from using CTF with deep-ripping to a depth of 35 to 40 centimetres on compacted sands in years with below-average rainfall.
“Unfortunately, in some parts of the wheatbelt in 2014, crop yields were disappointing where it was the first year of deep-ripping,” Ms Isbister says.
“Because of very hot weather, the bigger crop biomass produced at the start of the season from increased nitrogen (N) supply required more water to keep cool and the crop ran short of water to fill grain.
“Such effects should be lessened in coming seasons due to less mineralisation and supply of N from the ripping process.”
Economic analysis by DAFWA shows a $200,000 investment into deep-ripping, spading or inversion ploughing can be paid off within two years if CTF increases crop yield by about 9 per cent.
This is based on 2800ha of wheat grown per annum yielding 2t/ha without CTF at a price of $250/t and 8.5 per cent interest rate for the investment.
Dr Blackwell says it is possible to lift seeding capacity without compromising the CTF system.
“This is done by using higher speeds with wider tyne spacings – and twin row boots – and bigger air carts for a 12-metre-wide seeder, to produce the equivalent efficiency results as an 18m-wide seeder,” he says.
“The common use in WA of larger capacity seeding equipment with high axle loads to improve seeding and harvesting efficiency has very real risks of leading to very deep soil compaction problems.
“Axle loads of about 15t on wet sandy soil can induce root restrictions as deep as 50cm and this may be expensive to rectify in deep sands that need easy crop root access to meet yield potential.”
In a CTF system, all implements have a particular span (or multiple of it) – usually 9m or 12m – and all wheel tracks are confined to specific traffic lanes – usually about 3m.
Deep-tillage equipment can be modified by removing some tynes or spades to only cultivate to depth between the permanent wheel tracks when, or after, a CTF system has been set up.
More information:Dr Paul Blackwell, DAFWA,
08 9956 8555,
- NACC Controlled Traffic Farming Technical Manual
- Liebe Group
- Australian Controlled Traffic Farming Association
- More information about soil compaction can be found by searching ‘compaction’ on the DAFWA website
- NACC videos on controlled-traffic farming