On-farm trials push dual-purpose crop program

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Tasmanian growers Rob and Jo Bradley are building a robust mixed enterprise with dual-purpose crops.

PHOTO: Clarisa Collis

On-farm trials have recast dual-purpose cropping into a more profitable practice on the Bradley family’s 1020-hectare mixed-farming operation across two properties at Longford and Cressy in Tasmania’s Northern Midlands region.

Since hosting GRDC-funded Tasmanian Institute of Agriculture (TIA) research from 2011 to 2014 on their properties ‘Woollen Park’ and ‘Rosemount’, Rob and Jo Bradley have added Pacific Seeds Hyola® 971CL canola to their dual-purpose program, which comprises wheat, barley, ryegrass seed and clover seed.

In the past two years, they have found that grazing the brassica has lifted the crop’s productivity and profitability by pushing oilseed yields above three tonnes per hectare, as well as providing a nutritious feed for their 1600 composite ewes and 800 dairy cows. This on-farm outcome matches the results of research by TIA project officer Dr Peter Johnson, who demonstrated the dual-purpose efficacy of spring and winter canola varieties. On the Bradleys’ farms they yielded an average of 1.5t/ha of dry matter and 3 to 4t/ha of grain.

“Another advantage of growing dual-purpose canola is that we can use it to graze stock in April and May and lock up a more robust dual-purpose crop, such as ryegrass, so that it is effectively preserved as a standing haystack to fill the winter feed gap from July to August,” Rob says.

With dual-purpose wheat, the couple say trials examining the timing of grazing have also helped validate the emphasis they place on locking up cereals at growth stage 30 (GS30), or at the end of tillering before the first node appears. Highlighting the yield penalties that can occur where grazing continues beyond this, Dr Johnson says grazing SQP Revenue wheat until GS32, or the second node growth stage, reduced yields by 30 per cent in March-sown crops and by 75 per cent in May-sown crops.

The research also showed that sowing SQP Revenue wheat no later than March was optimal for both grain yield and dry matter production because early-sown wheat is more tolerant of grazing, Dr Johnson says.

“High-intensity grazing had a negligible effect on yield when wheat was sown before the end of March, whereas the same grazing pressure saw a 14 per cent reduction in yield when the crop was sown in April,” he says.

But in balancing the grain-and-graze benefits against weed control, the Bradleys are still prepared to sow dual-purpose wheat as late as April to help drive down ryegrass and wild radish weed seedbanks.

Feature: Grand design for grain and graze

“High-intensity grazing had a negligible effect on yield when wheat was sown before the end of March, whereas the same grazing pressure saw a 14 per cent reduction in yield when the crop was sown in April.”

– Dr Peter Johnson