Delving, claying improves Condingup sands
When Joe and Charlotte Della Vedova left the central Wheatbelt in 1995 in search of better rainfall and fewer frosts, they were soon to discover their new Esperance property would provide them with different challenges.
By 1998, Mr Della Vedova began in earnest his quest to create more fertile soils on his sandplain property between Esperance and Condingup by experimenting with claying some of his deepest sands.
Since then, he has found a system of claying, spading and delving that is achieving results across variable paddocks.
Mr Della Vedova was one of four farmers who spoke recently at the EDRS Field Day about his eternal quest to improve his infertile sandy soils and the lessons he'd learnt along the way.
It was soon after they moved to the coast the Della Vedovas realised issues such as wind erosion and non-wetting soils put limitations on crop yields, despite an average annual rainfall of around 550mm.
Mr Della Vedova initially tried claying his deep non-wetting sands with limited success, until in 2007 he realised that by incorporating clay using a spader to a depth of 50cm he achieved much better results.
"It became a process of soil rebuilding, involving delving or carting and spading of the clay being done across whole paddocks, depending on the soil profile," he said.
He said where clay was close to the surface and waterlogging was more prevalent, then delving worked well, whereas where the sands were deep, then the clay was spread.
"If there was a gravel layer within the profile, then delving could not be done, and the clay also needed to be carted to those areas and integrated from the surface downwards," Mr Della Vedova said.
Paddocks had been extensively soil tested and electromagnetic and radiometrics had been used to map where the clay and gravel were to help decide which form of earthworks to undertake.
Mr Della Vedova said the benefits included better topsoil pH (from 4 to around 7), a deeper root profile, higher organic carbon levels, a better use of fertiliser, better weed management, and more control over seeding times.
He said the soils that had been ameliorated were now more robust and workable with much better water-holding capacity. As a result, Mr Della Vedova had been able to lower seeding rates (5kg down to 2kg for hybrid canola) and got a much better response to fertiliser.
"The soil is now healthy, smells better and you can see worm activity there," he said.
Summer crops, such as sorghum, combined with stubble retention, were being used to increase carbon content and lower the water profile on wetter years in paddocks prone to waterlogging.
The process *
·Work on the sand hills first
·Do EM and gamma radiometrics
·Pre-drill sites for pits (check quality)
·Locate pits for maximum efficiency (closeness to paddocks and correct clay content)
·Source dedicated machinery
·Carry grader first and then delve to fill the gaps
·Sow cover crop
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