Farmer trials show cover is king by Guy Cotsell
Southern Queensland farmers and scientists working side by side in land management trials using controlled-traffic patterns are finding early confirmation that whether they till across the slope or up and down, high stubble cover is the answer to keeping erosion at a minimum.
But efficiency considerations — time and fuel savings resulting from longer tractor runs — tip the scales in favour of working up and down.
Controlled traffic offers great potential for lower costs and more timely operations. And thanks to the trials under way on six sites from Southbrook on the Darling Downs to as far west as Roma, farmers are already acknowledging these benefits and the collaborative researchers expect that data from their project and future farmer experience will provide further confirmation.
The trials, supported by the Federal Government and farmers through the GRDC, are investigating the cost benefits of controlled-traffic farming systems in southern Queensland as well as the runoff and erosion processes.
Phillip and Cindy Coggan farm in partnership with Mr Coggan’s parents, John and Lyn, 65 km south of Meandarra in southern Queensland. They crop 11,000 hectares in a rotation of wheat, sorghum and chickpeas.
Having already shown an interest in controlled traffic, they became more aware of its benefits when they saw how differently their max emerge disc openers moved on trafficked and non-trafficked areas in the paddock.
They now use controlled traffic for all their planting and spraying (the most frequent passes) but not for harvesting or cultivating because their machinery does not have the floating hitch needed to follow the contours. Mr Coggan says it’s too early to see an increase in yield, although he hopes this will occur. But he finds controlled traffic is already paying dividends in paddock management.
“Controlled traffic saves us costs by minimising overlap. It makes our paddocks easier to use, especially for spraying, because we have the wheel tracks to guide us. More importantly, it enables night spraying. We use marker arms to set out the paddocks before planting.
“It is much easier to organise — it enables two or three machines to run in the same paddock with no efficiency loss. There’s a bonus at harvest time — we can cut out squared blocks for the headers and avoid triangles.
“We haven’t noticed any significant difference in erosion between up and down or across the slope patterns, so we can concentrate on long runs — in fact, our paddocks are planned on achieving the longest possible runs where this suits us.
“Using CT with zero till, we are finding the soil better to plant into because the paddocks appear to be getting softer,” Mr Coggan said.
The Coggans have two self-propelled spray rigs with three-metre spacings — and have based their system on this machinery because “it is what goes over our paddocks the most number of times”. On-farm modification of older machinery has reduced spans from 18 to 14 metres.
No runoff disasters
Results of the trials to date suggest that runoff is slightly greater under controlled traffic and soil erosion has the potential to be greater but there is no strong evidence that it is so.
A one-year-in-20 rain event over three days in November 2000 at a site near Roma caused a 50 per cent runoff, but farmers who visited the site the following week saw only minor rilling, in particular in wheel tracks in the down-slope trial. Soil movement was minimal in both across- and down-slope treatments, and this was attributed to the high wheat-stubble cover (greater than 50 per cent).
The research team includes farmers and staff from the Department of Natural Resources (DNR), the Department of Primary Industries (DPI) and Conservation Farmers.
The farmers put in the controlled-traffic system in conjunction with research staff, undertaking all farming operations on the research sites, and recording details of management operations. DNR, DPI and Conservation Farmers staff installed the monitoring equipment and took measurements.
Low rainfall during the year 2000 reduced the expected number of runoff events, but early trends suggest that the up and down slope technique may produce slightly higher runoff. However, at this stage there appears to be little difference in soil erosion. Good falls in late January 2001 and in October and November 2000 still produced only negligible runoff.
What will happen with crop failure or low stubble crops remains to be seen. Initial focus was on minimum- and zero-till systems. However, farmer practices in the trial now vary from zero-till through minimum-till to full soil disturbance including deep ripping. This will enable the project in future to look at contrasting systems — providing it rains!
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Region North, South, West