Intercropping and companion cropping is not new. In fact Australia seems to be slow to adopt this concept showing great economic benefits elsewhere.

Our paddock observations agree with their findings ie some species are particularly good at sourcing specific nutrients from the soil and then sharing them with the other plants growing with them. 

This is the only logical explanation I have for why we see overyielding ie the combined yield of crops planted together, being greater than if species are planted as monocultures.

Definitely reason to explore suitable species to plant and harvest together in our part of the world.

https://www.stockandland.com.au/story/6976646/intercropping-a-possible-addition-to-cropping-systems/ Says:

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 would 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 had been sown in combinations to provide a mixture of functional groups – oilseeds, cereals and legumes. They were 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,” Dr Mitchell said.

“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 was 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 made 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,” she said.

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 were also six satellite sites.

The ‘Intercropping to exploit rainfall for profit’ project is a three-year investment.

More information about the project is available in two GRDC podcasts featuring Agriculture Victoria researchers at https://bit.ly/36ZaLNd and https://bit.ly/30ZXYGA.

To Read more about the potential role of companion and intercropping systems in Australian grain farming go to:

https://grdc.com.au/resources-and-publications/grdc-update-papers/tab-content/grdc-update-papers/2020/02/the-potential-role-of-companion-and-intercropping-systems-in-australian-grain-farming.-should-we-be-considering-them

https://www.academia.edu/18548428/Plant_diversity_and_overyielding_insights_from_belowground_facilitation_of_intercropping_in_agriculture?email_work_card=view-paper

For further interesting reading,