Crops on deep ripped soils show promise in dry season
Date: 15 Sep 2014
A trial at Buntine in Western Australia’s northern grainbelt is highlighting the potential benefits to crops from deep ripping treatments applied to compacted sands in low rainfall seasons.Wheat crops on the deep ripped plots have already grown roots and accessed water to a depth of 40cm below the soil surface – a much deeper level compared with the unripped plots.
One of the 2014 trials showcased at the Liebe Group field day on September 11, the trial is being conducted by the Department of Agriculture and Food (DAFWA), Liebe Group and CSIRO, with funding support from the Grains Research and Development Corporation (GRDC).
“In coming weeks, roots in the ripped plots may access soil water below 40cm and these crops could produce yields up to 0.5 tonnes per hectare greater than the crops on the untreated plots,” CSIRO researcher Phil Ward said.
In 2013, deep ripping by DAFWA of compact sands to 50cm at the Liebe Group trial site showed a benefit of about 1t/ha.
“It is one of the first WA deep ripping trials in which soil water is being precisely measured throughout the season, which will give researchers a better understanding of cultivation’s effects,” Dr Ward said.
Deep ripping is when soil is disturbed at depth, with strong, narrow tines, without inverting the soil.
With assistance from the Liebe Group, the deep ripping treatments were implemented on compacted dry soil on April 24, prior to crop seeding.In the ‘one-pass’ treatment, soil was ripped to a depth of 35 to 40cm, while the ‘two pass’ treatment involved cultivation to 25 to 27cm in the first ‘pass’ and 40 to 45cm in the second pass.
“During winter, there was virtually no water uptake at 20 to 40cm in the untreated soils, but there was significant water uptake and root growth at this depth in the ripped plots,” Dr Ward said.
“Plants in the ripped plots are expected to hold on and yield better if there is a tight finish to the season.”
DAFWA researcher Paul Blackwell said it was important to find ways of overcoming problems associated with deep ripping dry sands because it was usually more convenient for growers to deep rip soils when conditions were dry.
He said the trial had so far demonstrated little difference in water uptake and root growth between the one-pass and two-pass deep ripping treatments.
“However, two-pass deep ripping allows growers to deep rip bone-dry sands more easily and smaller soil clods are produced, which affect crop establishment,” he said.
Dr Blackwell said ‘shallow leading tine rippers’ – where shallow tines are attached on a ripper ahead of deeper tines – also produced these benefits and were cost effective.
“One-pass deep ripping normally costs about $50 to $70/ha and shallow leading tines can reduce fuel use by about 10 per cent,” he said.
Dr Blackwell said controlled traffic farming (CTF) systems - built on permanent wheel tracks where the crop zones and traffic zones are separated permanently - protected grower investments in deep ripping.
“It is best that these systems are established when deep ripping is done – by lifting ripper tines for the wheel tracks,” he said.
“CTF systems are important because a few passes of uncontrolled spraying traffic can reverse the benefits of deep ripping within a season and compromise its long-term benefits.
The Buntine trial is being conducted under the project ‘Minimising the effect of soil compaction on crop yield’, which is part of the collaborative research effort Soil Constraints - West.
Soil Constraints - West was developed following consultation with WA growers, through the GRDC western regional panel and GRDC Regional Cropping Solutions Networks (RCSNs).
More information about soil compaction can be found by searching ‘compaction’ on the DAFWA website www.agric.wa.gov.au.
Phil Ward, CSIRO
08 9333 6616, 0428 934 152
Paul Blackwell, DAFWA
08 9956 8555, 0429 102 105
Natalie Lee, Cox Inall Communications
08 9864 2034, 0427 189 827
GRDC Project Code DAW00234, DAW00634