Cropping

Closing the ‘yield gap’

By Country News

Potential exists for grain growers in southern Australia’s high rainfall zone to increase their wheat and canola yields by an average of 50 per cent, according to yield modelling.

The difference between today’s reality and tomorrow’s potential — known as the ‘yield gap’ — is the focus of a concerted research effort to enable growers to extract a great deal more from their crops.

Through the Grains Research and Development Corporation investment, researchers are developing new knowledge, tools, resources and recommendations to push yields and improve grower profitability.

Agriculture Victoria is leading the research initiative, which has established that by providing sufficient nutrients, wheat and canola yields can approach water-limited potential, except in cases of severe waterlogging or drought.

Agriculture Victoria Hamilton-based senior research scientist, Penny Riffkin, said the project had three main components, outputs from which will enhance understanding of crop physiology in order to identify crop types better suited to the high rainfall zone and also inform growers’ tactical decision-making in their quest to bridge the yield gap.

‘‘The first component is focusing on ideal wheat types that are better suited to this region, in terms of phenology and canopy architecture,’’ she said.

‘‘The second component involves looking at canola types — again phenology and canopy architecture — ideally suited to the high rainfall zone; while the third component is looking at how, with these optimum crop types, we can achieve higher yields through better management, in particular optimum nutrition.’’

The nutrition component of the research involves trials of wheat and canola, with the research focusing on interactions between multiple nutrients, including nitrogen, phosphorus, potassium, sulphur and micronutrients.

Research data from numerous field experiments across multiple sites is providing a better understanding of the responses to nutrients, both positive and negative.

‘‘It could be that putting on more nutrients will give you a 30 per cent yield increase, or in some cases it could even give you an 80 per cent yield increase, but it may not be economical to do so,’’ Ms Riffkin said.

‘‘Also, growers may not be necessarily getting the response to nitrogen that they were expecting and it could possibly be due to a lack of other nutrients, such as phosphorus, potassium and sulphur.’’

While nitrogen decisions can be made in-crop, a key finding from the research to date is that decisions relating to the application of phosphorus, potassium and sulphur must be made before the crop is sown.

More information is available at the GRDC Communities website at: communities.grdc.com.au