Research probes deep ripping timing and methods
Author: Natalie Lee | Date: 28 Nov 2016
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 best results.
Soil compaction is estimated to cost Western Australian agriculture at least $880 million annually and has been identified by Grains Research and Development Corporation (GRDC) Regional Cropping Solutions Networks (RCSNs) as a priority issue for growers across the grainbelt.
Department of Agriculture and Food (DAFWA) 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 also achieve 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 four to six metres 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 that 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 3cm sausage of hand-moulded subsoil in your palms it is probably too plastic and too wet to rip.”
Mrs Isbister said other options for deep ripping included:
- After seeding but early enough not to disturb establishing plants too much - generally within three days of seeding
- In the inter-row of crops sown on wide rows
- In a fallow year, which could be especially suitable for growers in low rainfall areas
Mrs Isbister said adopting a controlled traffic farming (CTF) system - involving the establishment of permanent wheel tracks - maximised the benefits of soil renovation achieved by deep ripping.
“The ripped soil can be very soft and more susceptible to re-compaction, and up to 80 per cent of re-compaction occurs in the first pass of machinery over the ripped soil,” she said.
The soil compaction 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 the RCSNs.
The GRDC, DAFWA, CSIRO and Murdoch University are funding the work, which is focused on non-wetting, compaction, acidity and other subsoil constraints.
More information about deep ripping is available on the DAFWA website via this link by searching ‘deep ripping’.
Information about soil management is also available on the ‘DAFWA – Soils WA’ Facebook page via this link.
GRDC Project Code DAW00243