WHILE sugarcane remains “king” in the Burdekin River Irrigation Area (BRIA), grain legumes used in rotation with cane crops are set to significantly change how the long-term monoculture is produced.
David Cox, Davco Farming, one of the Burdekin’s larger sugarcane farmers, says concerns over fertiliser and chemical run-off impacting on the Great Barrier Reef and the need to improve soil health have prompted the impetus for change in northern farming systems.
“We will be doing everything we can to reduce the amount of chemical and nitrogen being applied as well as minimising what leaves our farm,” Mr Cox says.
“We’re starting with composting and don’t know how effective or cost-effective that will be, but the strategy we know will work straight away is soybeans in our fallow.”
Mr Cox and Davco Farming operations manager, Evan Shannon, recently hosted the Grains Research and Development Corporation (GRDC) northern panel led by chair, James Clark.
Mr Clark says sugarcane production is likely to dominate the region for some time to come, however there is an emerging place for grain legumes which offer soil health benefits and other advantages such as nitrogen-fixing.
"When sugarcane prices are good – as they are now – there seems little incentive to plant ‘alternative’ crops, however we are hearing from leading growers that legume rotations are becoming more and more important in maintaining sugarcane yields and reducing fertiliser use," Mr Clark says.
Mr Cox says several other growers in the Burdekin region have been using legumes in cane rotations but the practice is limited by current high cane prices, a lack of processing infrastructure and local markets.
“We need to get all the logistics right, including planting equipment big enough to plant the crop in a quick enough time – there are contractors operating in the district who are assisting that,” he says.
“I expect to see a rapid expansion of soybeans in our fallows in the Burdekin over the next few years.”
GRDC funds several research projects into soybean management and varietal development, including the $450,000 per annum Australian Soybean Breeding Program.
GRDC analysis shows there is enormous potential for growth of soybean production provided good seed quality and the right crop maturation rates can be achieved.
Dr Andrew James, CSIRO plant industry leader says the amount of nitrogen contributed to the soil by legumes can be up to 300 kilograms/ha when grain is not harvested and up to 150kg/ha when grain is harvested, but its availability to the subsequent sugarcane crop can vary with crop management and biophysical conditions.
“It’s generally accepted within the industry that inorganic nitrogen fertiliser applied to the sugarcane crop in the first year can be substantially reduced, or even eliminated after growing a legume such as soybeans,” Dr James says.
Hugh Brier, Queensland Department of Employment, Economic Development and Innovation (DEEDI) senior entomologist says the spread of soybeans as a break and cash crop into coastal Queensland sugarcane areas has presented the industry and researchers with a number of significant pest management challenges.
These include the threat of flaring Silverleaf whitefly (SLW), for which there are no viable pesticide options in soybeans, and high densities of podsucking bugs, which severely reduce seed quality, and which can only be managed at present with non-selective pesticides.
Other challenges include a lack of integrated pest management (IPM) skills and knowledge in new production areas, an abundance of leaf eating caterpillars which inflict visually noticeable but frequently not yield threatening damage, and the ever-present soybean aphid.
Improving grower and consultant insect identification skills are a key focus of the northern grains/pulse IPM project funded by GRDC.
Mr Brier says identification skills are critical given that some key beneficial insects look like pests. For example, hoverfly larvae, major aphid predators, can be confused with leaf-eating caterpillars of the grass blue butterfly.
He says the soybean industry’s move towards edible soybeans, which have a far lower tolerance of bug damage in particular, has increased the pressure to develop effective pest management strategies for coastal production areas.
“The challenges outlined have brought dual benefits,” Mr Brier says.
“First, they have provided the impetus for research, development and extension that benefits for the entire industry, and, secondly, they have provided a focus on the need for IPM.
“We need an integrated approach to insect pest management that does not rely solely on insecticides to reduce insect damage.
“For example, the threat SLW poses for soybeans in Queensland, has increased the need for softer options and validated thresholds for all key pests.”
GRDC supports DEEDI’s IPM program. For more information, visit www.grdc.com.au
Email a friend