Fourth-generation orchardist Mitchell McNab may have won a 2016 Nuffield Scholarship to explore new technology, robotics and drones, but he’s also to experimenting with something decidedly low-tech: compost.
Mitchell, who works in his family’s agribusiness, H.V. McNab and Son, growing, packing and storing apples and pears and raising Murray Grey stud cattle, has been trialling compost made from urban green waste on seven hectares of the family’s orchard at Ardmona, in Victoria’s Goulburn Valley.
His aim is to ascertain whether fruit-tree crops benefit from the addition of composted household green waste and if so, how.
After just one season, he’s pleased enough with the positives of this old-school farming method to be scheduling another green waste compost application this spring.
“We got pretty good results,” McNab told Apple and Pear Australia Ltd (APAL) in August 2016.
The McNabs expected that having good cover in the form of compost would mean that the ground in the orchard trial plot retained more moisture. That was the case – but it wasn’t the only positive.
‘‘The trees were not as stressed during summer and, as a result, used less water,’’ McNab explained. ‘‘It means a better and more consistent fruit size and better pack out.”
The McNabs were pleasantly surprised to find that adding green waste compost to the soil also led to increased microbial activity around their fruit trees and better suppression of weeds.
To date, soil in the trial plot does not appear to be higher in nutrients as a result of adding the green waste compost: “We weren’t sure about how it would impact nutrient values — we are pretty sure it has not had an impact,” McNab said.
But until definitive soil test results are in, the jury’s still out on key nutrient counts.
Regardless, McNab plans to apply green waste compost to his orchard in the spring of 2016, reasoning that the water savings – along with better fruit size, consistency and packout – make the added effort worthwhile, especially given a likely future of climate-change induced droughts during which water costs are sure to soar.
“I think you would see the most effect in a drought year,” McNab noted, “when water prices are high.”
City green waste to crop-growth booster
The composted organic waste McNab’s been spreading on his trial orchard plot was produced at the new Veolia waste composting facility in Bulla, northwest of Melbourne, in a collaboration between Veolia, the Metropolitan Waste and Resource Recovery Group (MWRRG), and selected metropolitan councils in Melbourne’s north and west.
The household green and garden waste used to create the compost is collected from 11 metro council municipalities and transported to the state-of-the-art Bulla Organics Recovery Facility. Here, contaminates are removed from by hand before the green waste is shredded and prepared for in-vessel composting.
The green waste spends 10 days in Veolia’s high-tech concrete composting vessels, each with a built-in flexible membrane that seals the walls and steel door completely; air is pumped into the vessel via multiple distribution points in the base and, for three of the days, it is heated to more than 55°C to destroy any potentially harmful pathogens.
The resulting compost is screened, then transferred to various agricultural businesses across the state, including (but not limited to) broadacre agriculture, horticulture, biosolids management, manure blending, fertiliser blending and land rehabilitation.
Veolia’s Bulla facility processes as much as 85,000 tonnes of kerbside-collected urban green and garden waste a year to produce 50,000 tonnes of finished compost annually under its current 15(+5)-year North-West Organics Processing (NWOP) contract with the Metropolitan Waste and Resource Recovery Group (MWRRG) and the 11 participating metro councils.
Start your own composting trial…
While drones, sensors, robots and other precision-ag tools can certainly boost efficiency and productivity, improve management decisions and save labour and input costs on-farm, there’s a lot to be said for centuries-old sustainable farming methods, too.
Boosting soil moisture-holding and microbial capacity, improving fruit size and quality, and helping to ensure more urban waste is recycled productively makes green waste composting in horticulture sound like a good bet – and one that may well get better over time.
If you’re a grower not ready to go high-tech yet, this is a comparatively low-cost, high-benefit, sustainable and eco-friendly option you might want to consider while you’re amassing the capital for drones and robots.
Several metropolitan councils across Australia have established green waste recycling and composting schemes.
For more information about Veolia’s organic compost for agricultural applications, contact Veolia Australia. For information about composting options in your area, contact the Environmental Protection Authority (EPA) in your state and the waste division of your local council and/or the metropolitan council in your closest city.