CROP yields in high-rainfall zones are only achieving half their potential.

And new research by the Department of Primary Industries at Hamilton is trying to find out why.

    AT A GLANCE
  • Who: Penny Riffkin
  • What: farming in high-rainfall areas
  • Where: Hamilton
  • Why: realising the full potential
  • Report: KATE DOWLER

The work also aims to improve management of crops in high-rainfall zones and breeding better varieties that suit these areas.

Research leader Penny Riffkin said cropping in high-rainfall areas of southern Australia was constantly expanding.

"But yields are well below potential given the available resources of sunlight, water and temperature, with crops typically putting too much energy into biomass production," she said.

Researchers estimate that wheat was yielding half to two-third of its potential.

As a general rule, a high-rainfall zone was classified as receiving more than 500-550mm of rainfall annually.

"High-rainfall zones are different to other cropping regions for many reasons," Penny said.

"They have longer growing seasons and there are many more options for growers."

Penny said farmers in high-rainfall zones can focus on grain production, grazing them entirely or grazing early and then harvesting them for grain later.

They also have a wider sowing window and many cultivar maturity options.

"High-rainfall zones also have many management issues such as greater stubble loads," she said.

All these factors increase the complexity in developing germplasm and decision-making on managing the crops.

"But we can learn a lot from research conducted in the past from other regions within lower rainfall regions of Australia or from overseas high-rainfall zones," she said.

The project has launched two new tools to help at both the plant-breeding and crop-management level.

The DPI recently released a range of fact sheets that give farmers some clear data - compiled from verification sites run with the assistance of Southern Farming Systems and the MacKillop Farm Management Group - about the best management of high-rainfall zone crops.

The new data is gleaned from using existing simulation models combined with detailed, site-specific verification trials.

Penny said a series of workshops with farmers, run by SFS and the MacKillop group, identified what types of management options they wanted researchers to focus on.

"Strategies they wanted more information about were time of sowing, nitrogen fertiliser, stubble management, opportunity cropping, irrigation and grazing of crops," she said.

From there, case study sites were established so the simulation model information could be verified on the ground.

"There were seven on-farm case study sites, including three in Victoria, one in Tasmania and two in South Australia," Penny said.

The fact sheets are available on the SFS website.

"So farmers can now look at information, relevant to their area that gives them, for example, an indication of the best sowing times for wheat, and the likelihood of achieving the maximum grain yield at different times of year," Penny said.

Other data looks at nitrogen fertiliser application strategies.

"The response from farmers so far has been that this information is very useful, and gives them a quick indication of the likelihood of high yields, from certain management practices," she said.

Penny has also been working on a new tool to help breeders better understand high-rainfall zone cropping and the types of crops that will flourish.

"A new crop design tool has been developed, in collaboration with UK scientists, which takes historical climate data to quantify what resources are available and what the risks such as frost, heat and drought are," she said.

Based on physiological principles it then designs an efficient crop that will best use the resources and avoid risks.

Penny said the intention was that plant breeders would use this sophisticated technology to fast-track better, more-productive varieties for farmers in high-rainfall zones.