Data builds on WA deep ripping experience
GroundCover™ Issue: 126 | Author: Melissa Williams
Deep-ripping in WA:
- Primarily addresses soil compaction
- Suits deep and loamy sands, deep sandy duplex and some clay soils
- Involves using tynes to break up hard pans
- Has minimal soil mixing and has a typical working soil depth of 50 to 70 centimetres
- Costs $40 to $90 per hectare, depending on soil type
- Can improve wheat yields by 0.6 tonnes/ha in the first year after ripping
- Can have benefits lasting three or more years
- Ideally should be matched with controlled-traffic farming (CTF)
SOURCE: Department of Agriculture and Food, WA, trial results
Ripping soil to a depth of 30 to 50 centimetres is one of the most effective tools for addressing subsoil compaction on vast tracts of WA’s deep sands, sandy loam duplex and some clay soils.
Optimal results typically occur when deep-ripping is carried out just after opening rains in autumn. Soil is then moist enough to allow penetration of the ripping tynes, but not too wet, which can cause ‘smearing’ without shattering the compacted soil layers.
But this timing can be challenging because it coincides with high demand for labour and machinery in seeding operations.
GRDC Regional Cropping Solutions Network (RCSN) groups in each WA port zone are keen to find out the best alternative time to deep-rip and whether any particular crops are more responsive than others. Department of Agriculture and Food, WA (DAFWA) researchers have been investigating deep-ripping using a machine designed for operating in dry conditions. This is part of GRDC-supported collaborative research with a focus on soil compaction management through the Soil Constraints – West initiative.
DAFWA development officer Bindi Isbister says if the deep-ripper is strong enough and tractor traction is good, it can be more convenient for growers to deep-rip early in the year.
“Although the soil is dry, we are finding that deep-ripping can still break up compacted subsoil layers in these conditions and moisture loss is minimised,” Ms Isbister says.
“Other opportunities to deep-rip outside of the crop-sowing window include when there is out-of-season rainfall or during a fallow year.
“Deep-ripping in fallow can be particularly good in WA’s low-rainfall areas (with annual rainfall of less than 350 millimetres) to reduce risks of a yield penalty.
“This is commonly seen in crops sown after conventionally timed deep-ripping when there is a dry season,” Ms Isbister says.
DAFWA research and grower experience have found that later deep-ripping up to three days after seeding – early enough not to disturb establishing plants too much – can be successful on deep sands. But there is a risk of reduced crop establishment. She says some growers in the northern grainbelt have also successfully deep-ripped during the winter growing season in the inter-row of lupin and canola crops sown on wide rows.
Earlier DAFWA research found using a system of shallow leading tynes at a soil depth of 10 to 15cm, ahead of deep-ripper tynes operating at a depth of 30 to 50cm in the soil, could reduce the machinery draft force (force required to pull tynes through the soil) by 10 to 18 per cent on compacted soil. This can lead to significant fuel cost-savings.
Retired DAFWA senior research officer Dr Paul Blackwell says it can also be beneficial to use topsoil slotting plates that create soil flow into the subsoil when the topsoil is relatively dry (less draft force is required in drier topsoil).
“In moist soil conditions, growers in 2016 observed that soil built up on the slotting plates, which left trenches in the soil that increased the risk of poor seeding depth control,” he says.
“Using a weighted, or pressurised, cage roller behind the ripper smooths the paddock, break ups any clods and creates an even seedbed after any ripping operation.”
Dr Blackwell says deep-ripped soil can be very soft and more susceptible to re-compaction. He says best results come from adopting a controlled-traffic farming (CTF) system that minimises soil re-compaction and sets up firm pathways for machinery where the tramlines are not ripped. “Firm tramlines increase in-crop access, particularly in wet conditions such as in 2016, and reduce fuel use,” he says. “Leaving deep-ripped soil to settle for about two weeks can also help reduce seeding challenges after deep-ripping.”
Crop yield responses to deep-ripping in DAFWA trials across WA in recent years are outlined in Table 1, the data for which was collated by research officer Dr Stephen Davies.
The data indicates that, in sandy soils, yield gains of up to 75, 47 and 92 per cent are possible in wheat, canola and lupin crops, respectively, after ripping to a depth of 50 to 70cm (compared with no deep-ripping).
The yield response in heavier soils is lower, and deep-ripping can result in a yield penalty in some seasons with a very dry finish (such as 2016) or where there are other soil constraints.
|| Soil type
|Control yield (t/ha)
||Ripped 30cm||Ripped 50–70cm||Ripped 50–70cm + topsoil slotting|
|Yield (t/ha)||% change||Yield (t/ha)||% change||Yield (t/ha)||% change|
Bindi Isbister, DAFWA,
08 9956 8532,
GRDC Project Code DAW00243