Project looks at deep-ripping dry soil

Opportunities may exist for growers to deep rip compacted soils in coming months — in wet or dry conditions — and research is fine-tuning information about how they can achieve the best results.

Soil compaction is estimated to cost WA agriculture at least $880 million a year and has been identified by the Grains Research and Development Corporation’s Regional Cropping Solutions Networks as a priority issue for growers across the grainbelt.

Department of Agriculture and Food WA development officer Bindi Isbister, who conducts soil compaction research supported by the GRDC, said deep ripping was usually carried out in autumn after opening rains.

“However, this can put pressure on machinery and staff as the tractor used for deep ripping is usually the same one used for seeding,” she said.

“If the deep ripper is strong enough and the tractor can get good traction, it can be more convenient to deep rip in conditions that are as dry as possible.”

Ms Isbister said the research project had been investigating methods to deep rip dry soil, which can achieve a better “break out” than ripping in moist conditions.

“Previous DAFWA/GRDC research has shown that a shallow leading tine design — where shallow tines are attached on a ripper ahead of and in line with deeper tines — can reduce draft requirements (the load on the machines), fuel use and soil cloddiness,” she said.

“The work demonstrated that shallow leading tines can reduce draft force by up to 18 per cent when the leading tine works to a depth of 10cm on clay-textured soil, and by about 10 per cent on sandy soils.

“Using a weighted, or pressurised, cage roller behind the ripper (in any conditions) is essential to break up any clods and create an even seed bed.

“If ripping deeper (below 40cm) in dry conditions, ripper widths of 4m to 6m may be required to get enough traction to pull the ripper, particularly if ripping on commonly used 50cm row spacings.”

Ms Isbister said another benefit of ripping when soil moisture was low was the ability to use topsoil slotting plates, which seemed to work most effectively in these conditions.

She said deep ripping opportunistically after significant out-of-season rain was another option for growers in coming months but it was possible for soil to be too wet for ripping.

“Ripping soils — especially those with high clay content — in wet conditions can smear the edges of the ripping line, reduce the effectiveness of ripping and restrict plant root exploration beyond the ripping slot,” Ms Isbister said.

“If you can roll a 3mm sausage of hand-moulded subsoil in your palms, it is probably too plastic and too wet to rip.”

The research is part of the collaborative research effort, Soil Constraints – West, which was driven by the GRDC western regional panel after consultation with WA grain growers and RCSNs. The GRDC, DAFWA, CSIRO and Murdoch University are funding the work, which focuses on non-wetting, compacted, acid and other soil constraints.