Cotton and corn - ideal companions

A project to measure the benefits of using corn as a rotation crop could be the key to reversing some of the soil fertility decline in Australian cotton fields, according to a leading soil scientist at the Australian Cotton Research Institute.

NSW Department of Primary Industries Senior Research Scientist Nilantha Hulugalle said crops that provide large amounts of crop residues (stubble) are needed to address serious soil health problems that could affect the sustainability of cotton crops.

Dr Hulugalle believes that the beneficial impact observed by many growers after planting corn the previous season will be scientifically proven.

“There is strong anecdotal evidence that a maize (corn) rotation greatly improves subsequent cotton yield, with reports of the difference being quite striking,” he said.

“That’s not surprising as corn returns about 20 tonnes of stubble per hectare per season, which can significantly improve organic matter and the availability of nutrients such as potassium in the soil profile.”

The research will identify the soil and plant processes underpinning the beneficial impacts on cotton yield and quality and the overall economic benefits of cotton-corn rotation system.

“I expect this will provide the basis for adoption of maize by cotton growers as an alternative rotation crop for sustainable cotton production where the conditions suit, such as in Queensland and northern NSW,” Dr Hulugalle said.

The project is one which comes under the umbrella of the Cotton Catchment Communities CRC, and is jointly funded by the seed company Pioneer Hi-Bred Australia, the Grains Research and Development Corporation and the Cotton Research and Development Corporation.

It will be conducted over the next three years by University of Queensland (UQ) PhD student Alison Devereaux, under the supervision of Dr Hulugalle, Dr Longbin Huang, lecturer in plant nutrition and crop quality, and Dr Shu Fukai professor of crop physiology at UQ.

As part of her research, Ms Devereaux will investigate whether maize can improve soil structure, fertility and cotton growth more than the traditional wheat rotation.

Dr Hulugalle said the benefits of legumes and wheat as rotation crops on cotton yield and quality in irrigated cotton-based systems have already been proven.

“Legumes have their place, but overall wheat is a better rotation crop,” he said.

“However, we can only slow the rate of organic matter and fertility decline with a cotton/wheat rotation, and if we start putting corn into our system then we may be able to turn it around.”

Maize is a multi-purpose crop, with low capital investment and field risk (diseases and crop establishment), shorter growing season than cotton and flexible harvest time.

Any potential negative impacts of the corn rotation, such as the build up of insect pests, including the cotton bollworm, Helicoverpa armigera, will be considered as part of the research.

Further information on the project can be obtained from Dr Hulugalle at the ACRI on 6799 1500.