About 3.3 million hectares in Western Australia are at high risk of soil water repellence and 6.9 million hectares are at moderate risk
- Opportunity costs from lost production due to soil water repellence are estimated to be $250 million to $330 million per year in WA
- Management of soil water repellence centres on short-term mitigation,
long-term amelioration or avoidance/alternative land use
- Many WA growers are using a combination of strategies to target the problem
Non-wetting – or water-repellent – soils limit crop yields and are becoming more extensive and/or severe in many parts of Western Australia.
This issue is one of the top three research, development and extension priorities for WA identified by the GRDC’s Western Panel.
In an attempt to share grower and scientific knowledge about the best strategies to address water repellence, the GRDC’s Regional Cropping Solutions Networks (RCSNs) in the Albany and Kwinana West port zones organised two fact-finding bus tours this winter.
The bus tours through the northern and southern grainbelt regions complemented a new RCSN-funded booklet of water-repellence case studies called Combatting Non-Wetting Soils, which was produced in conjunction with the South East Premium Wheat Growers Association (SEPWA).
The aim of the tours and booklet was to highlight the systems being used by growers across WA and strategies being investigated through research trials to alleviate problems associated with water-repellent soils.
Growers from across Western Australia jumped on buses in mid-winter to inspect water-repellent soils and the management solutions being employed across the northern and southern grainbelts.
PHOTOS: Julianne Hill
The non-wetting soils bus tours attracted close to 170 growers from right across the state, who observed that in many circumstances a mix of methods worked best.
Leading soil-water-repellence researchers from the Department of Agriculture and Food, WA (DAFWA) and CSIRO, as well as consultants, participated in the tours to lend their knowledge to grower participants.
GRDC RCSN coordinator Julianne Hill says most growers visited by the tour group estimated that up to 90 per cent of their land was water-repellent.
“Its effects can include poor crop germination, staggered weed germination (making weed control difficult) and an increased risk of water and wind erosion,” she says.
“On or near-row seeding, delving, spading, mouldboard ploughing, discs, different sowing boots, wetting agents, claying, liming and other methods have been tried by the host growers, with many opting for a mix of methods to overcome their problem soils.
“Regardless of the method they used, host growers often stated that even though it was costly to manage water-repellent soils, increased returns in the first year alone were often enough to justify the initial outlay.”
Soil-repellence researchers Dr Margaret Roper, from CSIRO, and Dr Stephen Davies, from DAFWA, say the sites visited on the tours and the grower case studies included in the RCSN–SEPWA booklet demonstrate that water-repellent soils can be successfully managed by using many, often completely different, options – ranging from minimum soil disturbance to mouldboard ploughing.
DAFWA researcher Derk Bakker addressed growers at a clay trial site during the RCSN bus trip in June.
They say soil types and other factors, such as weed issues or soil acidity, will influence the systems that are most appropriate for use in a particular situation.
Dr Roper says claying, commonly used in WA’s southern cropping regions, seems to provide a virtually permanent fix for water-repellent soils – if done correctly – it improves the stability and structure of the fine sands in these areas.
“Some growers are also using near-row and zero or minimum-disturbance seeding systems to allow water to penetrate old root pathways and be taken up by crops,” she says.
Non-wetting researcher Dr Davies says some growers with ‘forest gravel’ soil types are using banded wetting agents, often in combination with on-row seeding, to achieve improved ‘wetting up’ and crop establishment.
“By viewing other growers’ soil-water-repellence problems and management approaches, participants were able to categorise their own non-wetting issues and think about the diverse array of options suited to their circumstances,” he says.
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Combatting Non-Wetting Soils is available at: www.grdc.com.au/GRDC-Booklet-CombattingNonWettingSoils
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