Intercropping is commonly used in backyard gardening, with the benefits well recognised, for example growing basil with your tomatoes.
To determine the potential of intercropping in broadacre systems, a state-wide project has been established.
Agriculture Victoria senior research scientist Meredith Mitchell said the project will determine if intercropping of two crop species when sown together within one space, could increase production and profits.
‘Four species mixtures are being evaluated: field pea/canola, faba bean/wheat, faba bean/canola and barley/canola,’ Dr Mitchell said.
These mixtures have been sown in different densities, ranging from a 50:50 mix where each species is sown at half its normal rate to 25:75 where one species is sown at a quarter and the second at three quarters of their normal rates. These are then compared with ‘monocultures’ where each species is sown at their full rate with no companion.
Dr Mitchell said the crops have been sown in combinations to provide a mixture of functional groups – oilseeds, cereals and legumes. They are sown together to complement their use of nutrients, light and water.
‘This can be achieved via different root systems that access different spaces in the soil profile; different canopy structures that can maximise light capture and provide physical support; and utilisation of nitrogen fixed by the legume component. It is about synergy and the value of plants working together.
‘In the second year of our research the experiment is showing intercropping has the potential to increase yield, value and profitability in cropping regions of southern Australia.
‘In 2019, six out of eight mixes evaluated had a small, but positive yield advantage, up to 20 per cent, over the monocultures.’
In Australia, intercropping is not widely adopted due to perceived additional labour requirements and the added complexity of managing and harvesting mixed species.
Dr Mitchell said new herbicide options available for a range of crops make intercropping systems a possibility for broadacre cropping.
‘Experimental plots were harvested with a conventional header and then the grains separated post-harvest. Further research is being undertaken to examine profitability and risk in a whole-farm context.’
The project is part of the Victorian Grains Innovation Partnership between the Victorian Government and the Grains Research and Development Corporation (GRDC), which aims to increase the profitability of southern grain growers through world-class research.
This research is part of a project that has core experimental sites at Rutherglen, Hamilton and Horsham.
In 2020, in addition to the core experimental sites there are also six satellite sites. The ‘Intercropping to exploit rainfall for profit’ project is a three-year investment.