HE was among the first group of farmers to get into clay delving almost 20 years ago – and to this day Bordertown farmer Roger Groocock still swears by its benefits.
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After seeing local farmer Clem Obst experiment with clay spreading, Roger and other members of the Wirrega-Lowan Vale branch of Agricultural Bureau of South Australia realised that spreading clay over their better country – shallow sands over clay – would be a good thing to do.
But as a result of increased organic matter through minimum till, water repellence was starting to show up.
They then started to wonder why they could not just rip up the clay from underneath the surface, which is what led to clay delving across Australia.
A trip to a water repellence workshop in Western Australia followed, where Roger came across the idea of a three-point-linkage delver – something his Agricultural Bureau branch quickly adopted.
Since the first trials took place in the area, Roger has seen a great increase in crop yields on his property.
"On our better country we've lifted our average wheat yields by between 70 per cent and 80pc," he said.
"We were looking at an average of 2.3 tonnes a hectare in wheat, now we're looking at closer to 4t/ha and we're disappointed if we don't get it."
Roger, who farms with wife Sue, planted wheat, barley, canola, beans and lupins last year, and despite the very dry spring, the crops did very well.
He credits the soil improvement work they have done with helping to achieve a good result in "trying circumstances".
But it was a trip to Europe in 2007 on a Churchill Fellowship that taught Roger how to get more out of delving.
He had heard about spading, and the aim of his trip was to see the spaders working and to investigate whether they had an opportunity in Australia.
"They definitely do," Roger said.
"In 2008 we started importing the Farmax spaders and now there's machines in duplex sandy soils across SA and Western Australia."
Roger uses his own equipment to delve in late-spring, rather than the conventional time after harvest. He does it at this time because there is more moisture and therefore the clay is softer, so it comes up easier and allows him to use 150-kilowatt tractors with front-wheel assist to drag the delver.
"The other reason I do it in spring is because the opportunity is there to spray-out what's there, you get some green manuring effect, and you get good root-disease control because you're destroying that green plant at that time of year."
But before Roger goes in with the delver he sows a forage rape crop and, after delving, clay is left on the surface and the pasture grazed by a 1300-head self-replacing Merino flock over summer.
Being grasseed-free makes this an ideal situation for finishing sale sheep for autumn markets.
"Leaving that clay on the surface over summer aids in the breakdown and mineralisation of the clay," he said.
After that period, which usually lasts until mid-March, the delved country is flattened with a railway iron or wide cultivator before being run over with the spader to mix the clay into the soil profile.
"Because the spader will work effectively to a depth of 300 millimetres it gives me the opportunity of mixing the clay deeper into the soil profile," Roger said.
Roger has found that canola is the best crop to sow first on delved ground, because it responds well to the treatment as a first-off crop.
He says any delved ground needs to be sown pretty early - preferably before 90 millimetres of rainfall post-break of the season – otherwise trafficability can be a significant issue because the ground gets too soft.
*Full report in Stock Journal, March 7 issue, 2013.
