Showcase for weed and lime strategies

Growers from the northern Wheatbelt who are proactively addressing the key issues of subsoil acidity, by using lime incorporation methods and herbicide resistance, have been included in a new Grains Research and Development Corporation’s (GRDC) Kwinana East port zone Regional Cropping Solutions Network (RCSN) group publication.

GRDC Western Regional Grower Services manager Roger States said the Kwinana East RCSN representatives initiated a bus tour and publication last year after identifying lime and herbicides as the inputs that impacted the most on their profitability.

“Growers in the low rainfall eastern Wheatbelt face highly variable seasons and manage the risk associated with this by maintaining low-input farming systems,” he said.

“Major issues the Kwinana East port zone RCSN identified were management and costs associated with herbicide use and lime incorporation.”

Mr States said Geraldton port zone growers had been particularly proactive in using strategies to address herbicide resistance issues and management of soil acidity throughout the soil profile.

The tour last year visited growers who were trialling tactics such as mouldboard ploughing or rotary spading to incorporate lime; using high rates of lime to hasten pH change; or managing herbicide resistance by using chaff carts, windrow burning, mouldboard ploughing, chemical fallow, tactical grazing and other methods.

“Research conducted by the Department of Agriculture and Food WA (DAFWA) estimates soil acidity costs growers on average $141 per hectare per year which equates to $1.6 billion per year in lost production potential,” he said.

“Of the strategies to manage subsoil constraints, liming is estimated to have the most potential to increase profitability – by about $63 per hectare, per year.

Mr States said surveys conducted by the Australian Herbicide Resistance Initiative (AHRI) in 2003 and 2010 had shown that while the incidence of herbicide resistance in annual ryegrass had remained relatively stable in the Kwinana East zone, this was not the case for wild radish.

“In 2010, 60 per cent of wild radish populations sampled were resistant to 2,4-D amine, 100pc were resistant to chlorsulfuron and 70pc were resistant to products such as Intervix - (imazamox (33g/L) plus imazapyr (15g/L) formulation),” he said.

The publication is available at