Growers can visit a cover crop trial site in the Riverina, where researchers are testing the economic feasibility of cover crop mixes in almond rows.
ALMOND growers will have the opportunity to visit a cover crop trial site in a Riverina almond orchard this winter. The Hort Innovation funded project is being run by Dr Thomas Lines at the University of Adelaide, and the findings will test the economic feasibility of cover crop mixes in almond rows.
The project aims to evaluate the impact of these cover crops on yield, soil health, water status/ stress, temperature, humidity, soil physiochemistry, carbon stocks and soil microbiomes.
The two trials are being run at the Almond Centre of Excellence at Loxton, and the other at Darlington Point in the Riverina, where the first year of seeding took place in May 2023.
At each site there’s five different treatments:
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A herbicide control with no cover crop
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A legume (medic, clover, vetch) mix
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A medic/rye/clover mix
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A pollinator mix
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A barley/vetch/radish mix (at the ACE orchard) and ‘big blend’ mix at Darlington Point consisting of a chicory, vetch, plantain radish, brassica, rye, clover, quinoa and oat.
Darlington Point has higher rainfall than Loxton, so treatment five was altered because the Riverina site could handle more water demanding species.
University of Adelaide Research Fellow Doctor Thomas Lines said canopy temperature and humidity data that’s been collected so far is showing significant differences between treatments in heating and cooling.
“The tree canopies next to the bare earth treatments are warming and drying faster at the start of the day. This is likely to influence some phenology of the trees,” he said. “More detail is being explored, and the addition of the microtensiometers next season will really help demonstrate whether there is a real world effect on water usage and stress.”
Dr Lines said the trials are generally sown in early May but timing is important, especially if orchards get waterlogged or, conversely, get very little rain.
“Try to sow as late as possible without missing the first serious rains of the season,” he said.
“If in doubt, sow early. Late sowing might miss rain and may not give the cover crop time to flower.”
The majority of Australian almond orchards have drip irrigation and Dr Lines said it is still viable to grow a mid row cover crop.
“While full-floor planting would be ideal to maximise the ecosystem services of cover crops, (such as improvements in water retention, heat reflectance, soil structure improvement) current harvesting methods mean it is not practical,” he said.
Dr Lines said it's still too early to make a call about the best cover crop mix to use in an almond orchard.
“In addition to looking at water usage in the different treatments, we also expect there will be differences in soil characteristics, but these can be slow to change,” he said. Dr Lines said harvest can continue as normal, but slashing or terminating the cover crop at the right time is important.
“Cover crop selection is also critical in defining the challenges you might have at the busy end of the season,” he said.
The cover crop workshop will be held on Wednesday, 27 August at Darlington Point.
Keep an eye on the ABA’s events page for further details, including the registration link.