Australia
March 12, 2013
New research has confirmed that crop establishment and productivity can be improved on non-wetting sandplain soils by modifying furrow sowing techniques.
The trials at Badgingarra were established as part of Grains Research and Development Corporation (GRDC) supported non-wetting soils research conducted by the Department of Agriculture and Food (DAFWA).
Poor crop establishment on non-wetting sands sown with knife points. Photo by Stephen Davies, DAFWA.
DAFWA researcher Stephen Davies said the trials were in response to findings that furrow sowing with knife point seeding systems, while very effective on many soil types, appeared to be much less effective on non-wetting soils.
“The dry, repellent sand tends to flow around narrow knife points at seeding and become concentrated in the sown furrow, resisting wetting up and reducing establishment and timely germination of the crop,” he said.
“The problem tends to be expressed more with dry or partially-dry sowing, and where soil water repellence is more severe.”
Dr Davies said the 2012 trials investigated seeding system modifications to improve the wetting up of the seeding furrow - either by reducing the flow of water repellent soil into the furrow at seeding, or improving the capacity of the furrow to wet up, primarily through the use of banded wetting agents.
“Initial findings from the trials show that it is possible to improve crop establishment and productivity on water repellent soils using modified furrow sowing techniques,” he said.
“Banded wetting agents are helpful with early or dry sowing before opening rains, but tend to be less beneficial when used later in the sowing program when rain has fallen and the soil has started to wet up more.
“In areas at high risk of wind erosion the use of banded wetting agents may be safer than the options of using alternatives to knife points – such as winged points or boots which can cause more soil disturbance.”
Dr Davies said the trial results found that winged points and winged paired row systems performed better than knife points under certain soil conditions, but these benefits were variable and there might be little advantage from using them in some sowing conditions.
“Winged points look most attractive when shallow moist soil can be ‘delved’ to the seed zone to provide early establishment,” he said.
“Winged paired row seeding systems have produced better cereal yields than single row knife point systems in a number of trials and demonstrations over several seasons, and growers are starting to test and use these systems on-farm.
“Growers are also finding that simple approaches like sowing next to or at a shallow angle across the previous year’s crop row, and broadcast spreading a portion of the seed in front of the seeding tynes, are relatively simple techniques that can improve establishment on water repellent soils.”
Dr Davies said that whole farm income could be improved through soil water repellence mitigation options such as wetting agents and paired-row seeding.
“One recent grower case study demonstrated that whole farm income was improved by $77,000 using a conservative grain yield benefit of 100kg/ha, through the use of a more effective seeder for water repellent soils, compared with a typical knife point seeder,” he said.
Dr Davies encouraged growers with non-wetting soils to use combined strategies – including short-term and long-term amelioration options – to manage water repellent soils.
“Treatments such as claying, mouldboard ploughing and spading often give greater and longer-lasting yield increases than options such as seeding system modifications, but are slow and costly to implement,” he said.
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