As part of a Landcare Australia funded project, ‘Smart Farms, Small Grants’, BioResEd conducted a case study trial on inter row cover cropping in an avocado orchard in Bundaberg, Queensland, for the purposes of sharing this experience with other growers.
This orchard was planted in 2018, with 9 x 5 m spacings for its 4891 trees on 22 Ha. The soil types are red loam and grey loam. Prior to the trial, the grower had been reducing chemical usage and focusing on soil health and Integrated Pest and Disease Management, and he had previously seeded the inter row with a mix of signal grass, Rhodes grass, barley and couch. Signal grass had since become dominant to the exclusion of the other species.
Goals for the trial were to increase plant species diversity and improve soil health. Potential challenges associated with inter row cover cropping for this orchard included finding cover crop plant species to suit the soil conditions, as well as the lack of inter row irrigation for cover crop establishment in this climate.
Species suitable for the seed mix were drawn from standard commercial options currently available as cover crops. These species were also screened for ‘pest reservoir potential’, weediness and/or dominance, and suitability and practicality for standard inter row management. Seed mix options were given for each of autumn in 2021 and 2022 as well as spring of 2021; you can view these in the full report.
The decision was made not to use additional irrigation, so the trial relied on existing sprinklers that were already in place along the tree line, which had a reach of 2 m into the inter row. Instead of seeding along the centre strip, this area was left with signal grass on a reduced slash-program. The signal grass directly adjacent to the trees was mulched and cover crop seeds were planted using a direct drill seeder into the mulched signal grass.
The results of these seedings were that tillage radish, triticale, woolly vetch and chicory established well, providing soil health benefits and resources for beneficial insects.
Thank you to the grower, Clinton Scott.
