Darren Jensen sees Kyabra chickpeas emerge from paddocks showing reduced weed pressure after strategic cultivation.
PHOTO: Clarisa Collis
On-farm trials have cast strategic cultivation as a profitable approach to weed control on the Jensen family’s 1750-hectare grains operation at Biloela, Central Queensland. Overturning 15 years of no-till farming practices on their cropping country, Darren and Tanya Jensen revived tillage to help manage weeds on their property in 2015 and 2016.
To date, they have found that ploughing their soil has lifted both the productivity and profitability of their summer and winter crops: sorghum, maize, chickpeas and wheat.
This on-farm result matches the findings of GRDC-funded research from 2012 to 2014 on the structured vertosol soils across the farming couple’s property.
The trials, led by Dr Yash Dang through the University of Queensland and the Queensland Department of Science, Information Technology and Innovation, showed that strategic tillage has the potential to lift both grain yields and gross margins, as well as maintaining soil health. However, Darren, who was 2015 Grain Grower of the Year, says ploughing the soil has provided other benefits in addition to those demonstrated in the trials.
Since using two passes of a chisel plough to cultivate 1400ha last year, and again tilling this area with one pass of a disc chain this year, the Jensens have eliminated three fallow herbicide applications from their spraying regime.
Darren says this has delivered a herbicide cost-saving totalling about $84,000 based on the $20/ha price for chemicals alone. Plus, the reduced spraying has decreased their reliance on chemical weed control, mitigating herbicide-resistance risk.
Strategic tillage targeting a suite of weeds – fleabane, sow thistle, African turnip and, in particular, feathertop Rhodes grass – has also enabled the Jensens cut seeding rates. Darren says less in-crop competition from weeds following tillage has meant they can reduce plant populations, resulting in more robust plants and, ultimately, higher-yielding crops. For example, reducing their sorghum seeding density from 45,000 seeds/ha to 35,000 seeds/ha has provided a $12/ha cost-saving.
More importantly, in dry seasonal conditions, a low plant population can mean the difference between a harvestable yield and crop failure. “The effect of lower seeding rates on sorghum profitability can be huge,” Darren says. “In a very dry year it could rescue a crop from complete failure so it returns about $200/ha. Whereas in wetter seasons the yield gains tend to be smaller because there’s more moisture per plant.”
Another benefit of cultivation on the Jensens’ property is that it has restored about five per cent of their weed-infested country to cropping, further lifting overall farm business productivity and profitability.
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Strategic tillage puts the pressure back on weeds
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