Orchard recyling t sustainability first
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In A Nutshell - Autumn 2022 Vol 23 Issue 1
THE traditional method of orchard upgrades in Australian horticulture has involved removing old trees , burning them and then ripping the ground in preparation for new plantings . The environmental impact of such practices has been brought into question in more recent times and almond growers in California have long been exploring more environmentally beneficial methods to get the same job done . Whole Orchard Recycling ( WOR ) research has been sponsored by the Almond Board of California and the University of California and the results over the past decade have Australian growers sitting up and taking notice . The trials have involved researchers measuring soil health and tree productivity of an almond orchard that returned mulched up old almond trees back into the soil and compared it with an orchard that burned its old trees nine years earlier . The orchard that use tree recycling had a 20 percent decrease in irrigation to quantify its water resilience . The results , published in Science Daily two years ago , found that , compared with burn treatments , whole orchard recycling can :
• Sequester 5 tons of carbon per hectare
• Increase water-use efficiency by 20 percent
• Increase crop yields by 19 percent .
Long-time Australian grower and former ABA chairman Neale Bennett has been pondering the benefits of such a trial in classic Aussie almond growing conditions and earlier this year took the plunge . He has teamed up with SARDI and Hort Innovation to conduct the first scientific WOR program of its type in Australia at his Merbein property . Mr Bennett was one of the early adopters to growing almonds in the Sunraysia and ironically it was his first patch of almonds that has gone back into the ground as part of the project . Just under 3ha of 30-year-old trees have been bulldozed , mulched and returned into to freshly ripped old orchard floor before replanting . The trial is based on the fact that almond trees accumulate significant amounts of carbon during their lifecycle . The Bennett trial will provide better insights into whether the traditional sandy soils of Sunraysia and Riverland can capture the same sustainable outcomes the Californians have enjoyed . Unfortunately , when an orchard reaches the end of its commercial life , this resource is traditionally managed through burning as part of the orchard redevelopment . While burning is a quick and effective means to clear debris from the site and can reduce pathogen load , it also releases significant amount of carbon that could potentially be sequestered or at least incorporated to improve soil organic matter , fertility and help with the establishment and productivity of the new orchard . Orchard recycling involves pulverising the tree and putting it back into the soil . The trial at the Bennett orchard aims to quantify the impact of whole orchard recycling on the carbon footprint of an almond orchard , including the impact on carbon storage and turnover in the soil , soil greenhouse gas emissions and the carbon accumulation by the newly planted trees .