Win-win – feeding stock while reducing weeds
23 November 2017
The use of chaff carts at harvest has won many fans in WA, who see them as a means of controlling the weed seed bank while providing summer sheep feed.
But does it offer value over simply grazing traditional crop stubble?
Members of a local farming systems group, the Gillami Centre, and farm consultant Ed Riggall of AgPro Management, are using an MLA Producer Demonstration Sites (PDS) project to further investigate.
Running for three years until 2020, the first trial will start shortly to assess ewe performance from grazing paddocks with chaff piles, versus grazing traditional crop stubbles with supplementary feed – as per common district practice.
At Toolbrunup, in a 400 millimetre annual rainfall zone in the Great Southern region of WA, producers Stuart and Connie Witham have towed a chaff cart behind their header for the past three years. They will be hosting the first trial on their property.
“Annual ryegrass goes nuts here during our wet winters. Capturing its seed at harvest, and then destroying it by grazing the chaff and burning any residue the following autumn, significantly reduces weed burden in our cropping paddocks,” Stuart said.
“In three years, we have noticed paddocks are cleaner (from weeds). We now tow the chaff cart across our entire harvest of canola, wheat, barley and faba beans.
“While this can marginally slow the header down, the longer-term weed control benefits are well worth it.”
Stuart said the chaff piles – commonly known as ‘dumps’ – provided highly valuable and ‘no-cost’ sheep feed during the summer, when annual pasture production had stopped.
“We start grazing sheep on the chaff piles as soon as we finish harvesting each paddock, beginning with canola because they take to that really well and there is no induction period needed,” he said.
“We’ll graze sheep on the piles from about mid-November to February, when we join the ewes and start adding extra supplementary feed until pastures get away in autumn and winter.”
In the past two years, the Witham's property has had wetter than average summer periods where chaff piles had proved invaluable, as they did not get wet in the middle where the sheep would ‘burrow’ in to eat.
He said since the grazing of chaff piles was leading to ewes maintaining higher condition scores during summer, leading to improved conception rates and higher productivity.
Twin pregnancies in the Witham’s older ewes have lifted by up to 20% in four years to about 40–50% of the total flock and conception rates in maiden ewes have risen by about 10%.
In Stuart's experience, sheep grazed the canola chaff piles right down to ground level for easy burning of any residue prior to the next year’s crop sowing in about April. Cereal chaff piles tended to have more residue left behind.
“When we burn the chaff piles after grazing and before seeding, we have found the hotter the burn, the better the result we get in destroying weed seeds,” he said.
“There is a lot of information available about how to achieve that, especially on the WeedSmart website.”
Putting it to the test
Ed Riggall said the focus of the PDS was to show local producers the potential for using the chaff piles to lift sheep weight and condition score by at least 10% and lambing rates by at least 12%.
His previous research into sheep grazing of chaff piles in WA’s Great Southern region found weight gains of up to 3.5kg/head can be achieved over a six week period.
Ed said economic analysis through the PDS project would help to determine the sheep feed cost and labour saving benefits to the whole-farm from not using as much supplementary feed.
T: 0428 299 007
Michael Crowley, MLA
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MLA Producer Demonstration Sites: mla.com.au/pds
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