More than 20 years of research into soybeans is paying dividends for Queensland’s cane farmes.
The Department of Agriculture and Fisheries (DAF) is working closely with the farming sector and the Grains Research and Development Corporation (GDRC) to double soybean production within three years.
DAF Principal Farming Systems Agronomist Neil Halpin says the research findings show soybeans are a great fit in high-rainfall coastal and hinterland areas such as Bundaberg, Mackay and the Burdekin for farmers wanting a legume rotation crop.
“Our department has been involved in a range of soybean research projects over the last 20 years or so and we’ve come to understand just how valuable this legume is in the sugarcane farming system,” Mr Halpin says.
“Research that was undertaken as part of the ‘Sugar Yield Decline Joint Venture’ has shown that cane farmers can expect a 10% yield increase in the plant cane crop following a well-grown soybean crop compared to a plough-out re-plant.
“In fact, our research shows that the yield increase continues through the ratoon cycle and that the monoculture plots were due for plough-out a year earlier than our legume rotation plots.”
Mr Halpin says the DAF research also showed that a well-grown crop of soybeans can return 300kg of plant-available nitrogen to the soil for the following crop to use if green manured.
“Growers who are growing soybeans for harvest can gain extra income from the soybeans and still expect 60kg or more of ‘free’ nitrogen for their next crop,” he says.
By improving soil health and the soil’s biological, physical and chemical fertility, growers can increase sugarcane yield, thereby improving input use efficiency, improving profits for the farmer while reducing environmental loss pathways.
Mr Halpin says the soybean expansion project will hold several pre-season and in-season soybean agronomy field days beginning in November 2023.
Growers who are interested in more details about upcoming events are urged to subscribe to the DAF Soybean Update by emailing their details to carla.atkinson@daf.qld.gov.au
Long-term soybean growers Jeff and Judy Plath from Childers believe the benefits soybeans offer their farming business go well beyond a simple pay cheque for their crop.
“I saw the immediate benefits of soybeans in our farming system when I first grew them around 20 years ago,” says Mr Plath, who has incorporated the popular legume into his cane farming rotation ever since.
“Not only do soybeans supplement our income, they also improve our soil structure, return nitrogen to the soil, and allow us to reduce cultivation in our farming system.”
The Plaths use a zero-tillage planting system that allows them to plant the soybeans directly through the trash from the previous cane crop.
After the soybeans are harvested, the soybean trash is left intact for as long as possible to protect the soil from erosion, conserve soil moisture, improve soil organic matter levels, and allow strategic release of the nitrogen stored in the soybean plant material.
This practice better aligns the release of nitrogen from the soybean residue with when the sugarcane crop needs it.
“Prior to planting sugarcane, I cultivate the soybean paddock with two passes, which saves time and money and conserves moisture and nutrients in the soil,” Mr Plath says.
“Occasionally the seasonal conditions mean I need to cultivate earlier, or more often, but in general over the last 10 years or more I have been able to plant most of my soybean blocks back to sugarcane with minimal cultivation.”
