Multiple approach to non-wetting soils in Badgingarra
Like many wheatbelt growers, the Kenny family at Badgingarra is striving to find the most efficient and cost-effective tactics to combat non-wetting soils.
Much of their 4300-hectare property suffers the classic symptoms of this problem, with poor soil water-holding capacity, soil water repellence and acidity. These are major limitations to boosting cropping productivity.
To manage these issues, Andrew and Gina Kenny and Andrew’s parents Mike and Sara are using a range of short-term mitigation and longer-term amelioration strategies.
These include clay incorporation, improved sowing systems using a winged, paired-row seeder and one-off mouldboard ploughing.
Andrew says clay incorporation is the most effective amelioration remedy, producing significant crop yield increases where it has been used on about 300ha.
Many of his neighbours are successfully using clay incorporation and spading as long-term amelioration strategies – at a cost of about $800/ha. Andrew has recently sought more economically viable solutions.
One-off mouldboard ploughing at a cost of about $150/ha is allowing us to treat more hectares than we could with claying,” Andrew says.
“We have mouldboard ploughed about 600ha in the past two years and the short-term results are encouraging, with yield benefits of more than one tonne/ha.
“But we have not yet determined how long these benefits will last. If it is only going to be four or five years, there may be no advantage over claying. But if the benefits last for eight to 10 years, it will be economic.”
A short-term, cheaper, mitigation option of a winged-boot, paired-row seeding system was trialled by the Kennys in 2011.
For an estimated cost of about $10/ha, it outperformed their knife-point seeder in crop establishment and soil moisture-holding ability.
Crop establishment was up to 50 per cent higher on severely water-repellent deep sands and 36 per cent better on sandy gravels where the winged, paired-row seeder was used.
This success led to the purchase of a $150,000 parallel linkage Morris Contour Drill with a winged boot, which was used for the Kennys’ entire 2245ha cropping program in 2012.
“The paired-row seeder effectively has 50 per cent more seeding row, which increases the chances of seed landing in wet soil, and the wings means it potentially grades the water-repellent soil out of the wider furrow better,” Andrew says.
Owners: Andrew and Gina Kenny,
Mike and Sara Kenny
Location: ‘Rubicon’, Badgingarra
Farm size: 4300 hectares
Enterprises: grain, sheep, cattle
Average annual rainfall: 480 mm
Soil types: variable, from pale deep sand to sandy gravel
Soil pH: 4.2 to 6 (surface average)
Ideal crop rotation: wheat/canola
Crops grown 2012: wheat (750ha), canola (650ha), barley (650ha), lupins and oats (195ha)
Do the economics stack up?
A recent economic analysis of the mitigation and amelioration options being used by the Kennys was carried out by the Department of Agriculture and Food, Western Australia (DAFWA), led by research officer Dr Stephen Davies and funded by the GRDC.
This was part of a series of grower case studies conducted across the Kwinana West zone that were supported by the local Regional Cropping Solutions Network.
The DAFWA analysis showed the Kennys’ combined new seeding system and mouldboard ploughing strategies to manage non-wetting soils boosted whole-farm profits by $131,700 in the first year (2012).
This was based on net benefits of $19/ha and an expected cereal yield increase of 0.1t/ha for the winged-boot seeder and expected cereal yield increases of 0.9t/ha for mouldboard ploughing.
Andrew says these forecasted yield benefits are conservative, especially for mouldboard ploughing, which had contributed to the best yields ever achieved on some paddocks in 2012.
He says large-scale trials on the farm in 2012 showed mouldboard ploughing lifted wheat and barley yields by more than 1t/ha – to 4 to 4.8t/ha on good gravels – and by 0.5 to 1t/ha for lupins (Table 1).
Andrew says mouldboard ploughing led to a reduction in herbicide use in 2012 and would be an important tool in managing resistant ryegrass in future.
However, he says there are limitations with trifluralin effectiveness in paired-row seeding systems.
This year, the Kennys will again use the paired-row seeding system for the bulk of their cropping program and, depending on the timing of opening rains, undertake more mouldboard ploughing.
Andrew says the combination of short-term, relatively inexpensive mitigation options and more expensive long-term tactics appeared to be a productive and financially sensible approach to managing non-wetting soils on their property.
Dr Davies says other local growers are also having success with mitigation methods using banded wetting agent with knife-point systems.
He says a comparative trial in the district in 2012 by the DAFWA team showed winged-boot paired-row seeding or banded wetting agent with knife points could lift wheat yields by more than 0.5t/ha and assist weed control on severely water-repellent sand compared with traditional knife points.
See local Badgingarra grower Andrew Kenny speak about the combined short and long-term soil mitigation and amelioration methods he is using in an attempt to reduce the impact of non-wetting soils on the family farm:
0428 529 110,
See Steve Davies 2013 Agribusiness Crop Updates Paper at www.grdc.com.au/UpdatePapers
See the March – April 2013 ‘Water Use Efficiency’ Ground Cover Supplement for more information.
GRDC Project Code DAW0024