Clay and stubble turn around the sands of time
GroundCover™ Issue: 103 | Author: Brad Collis
Joe Della Vedova does not beat about the bush when he talks about the country he crops east of Esperance: “Non-soil,” he says of the sand plain just 20 kilometres from the Southern Ocean coastline.
The non-wetting sand is the underlying production constraint for the 9200 hectares that he and his family crop; effectively halving the yield potential that the high-rainfall environment could otherwise be delivering.
It is for this reason that he invests time, effort and money into a two-pronged strategy to gradually turn this sand into something more akin to a soil – a soil much better able to store moisture and nutrients and lift yields closer to their potential.
Joe is using a combination of maximum stubble retention and claying to gradually change the biological and physical properties of the medium into which he sows his crops, and the effort is paying off.
The treated areas are now delivering up to six tonnes/ha – 50 per cent up on the 4t/ha average and well on the way to his 8t/ha goal.
Joe begins his stubble-management program at harvest, fitting the headers with Shelbourne stripper fronts. He explains that these improve stubble retention, and subsequent soil structure and biology, by stripping the head off the cereal and leaving the whole stubble length in the paddock. “This leaves a thatch of material covering the soil, holding in moisture and building soil carbon. You can see the benefits as soon as you get a summer rain – earthworms appear.”
Joe has fitted hydraulic coulters in front of the seeder bar tynes and says this makes sowing a straightforward operation, despite the heavy stubble load.
For claying, Joe digs his own pits – the clay layer being from just 0.5 to 1.5 metres below the sand – and sites them within a two-minute drive of the area being treated.
“It costs us about $600 a hectare – a third of the contractor rate because we have our own equipment – and it generally pays for itself with the first crop grown on the area that has been clayed.”
Joe regards the claying program as ongoing and the amount of added clay has been gradually increased to 1000t/ha.“It’s a lot of work, but we are getting enormous gains. Unfortunately, just as we’ve achieved this potential the past few seasons have had dry finishes. But the vegetative matter in the crops where we have clayed is tremendous, so we can see the yield potential the next time we get a good finish.”
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