BioCycle January 2011, Vol. 52, No. 1, p. 46
Among the initiatives of the Compost For Soils program is funding scientific research. Positive results using finely screened commercial organic compost in the vegetable, orchard and vineyard markets are described.
Angela Lush

THE Compost for Soils program in South Australia began in 2006 when three compost producers – Jeffries Group, Peats Soil and Garden Supplies and Van Schaik’s Biogro – joined forces to change consumer opinion of their products and to educate their markets about the benefits of using compost. “The perception in our markets was that our products were simply piles of dirt,” says Jeffries Group Managing Director Lachlan Jeffries, one of the three producers involved. “It’s taken a long time to change that perception, and the Compost for Soils program is now building momentum in that area.”
Although fiercely competitive at point-of-sale, the companies each recognized the value of working together to offer clients consistent, quality information and to develop new and innovative products and applications under the umbrella of the Compost for Soils program. Among the feedstocks they process are green organics, including food waste, and by-products of forestry and agriculture.
Zero Waste SA (South Australia) has been a key partner in the Compost for Soils program by providing additional funding. Zero Waste SA promotes waste management practices that eliminate waste or its consignment to landfill and provides grants for a range of waste management projects including infrastructure, technology, systems and resource efficiency. Zero Waste SA also helps industry develop markets for recovered resources and recycled materials.
Major agricultural markets for compost use within South Australia include vegetable, orchard and vineyard producers. To increase the awareness of compost use as a viable option in these production systems, the Compost for Soils program took two main approaches: investing in high-quality scientific research and increasing market presence as well as consumer education. The Compost for Soils program invested in applied scientific projects across their three key markets, with research focusing on novel uses of compost. The following sections describe recent research utilizing finely screened commercial organic compost in the vegetable, orchard and vineyard markets.

Vegetable Production
Matt Ayres, a research officer with the South Australian Research and Development Institute (SARDI), has been investigating the potential of compost to combat disease in vegetable crops. Soil-borne diseases account for a significant proportion of crop loss and failure in the Northern Adelaide Plains, a large vegetable growing region in South Australia. High-value crops with a quick turnover are under increasing pressure from disease, and without the luxury of crop rotation, disease control is difficult for many growers. Root and stem rots as well as wilts can be caused by fungi in the soil, such as Fusarium, Pythium and Rhizoctonia. These have been controlled in the past by the soil fumigant methyl bromide, but since this product was banned for this type of use, new methods of disease control are needed.
A number of greenhouse pot trials have shown significant suppression of soil-borne root and stem disease when compost was applied. In one trial, compost incorporation reduced plant root disease by 72 percent in capsicums (peppers) and 64 percent in tomatoes when compared to soils without compost. These high levels of disease reduction would represent significant benefits to vegetable growers in addition to improvements in soil quality and water- holding capacity that compost incorporation also offers.
As well as testing composts to combat disease, Ayres is investigating the impact of compost on yield, fruit quality and the shelf life of produce. Preliminary results indicate crops like capsicums may ripen more evenly when compost is incorporated into the soil. This means growers may be able to harvest less often, saving time and money. At this stage, research is focused on cucumber, eggplant, capsicum and tomato greenhouse crops, but it is expected that compost will also have a major role to play in disease suppression in field crops such as potatoes, onions, carrots and lettuce.

Vineyards
The common challenge of improving compacted and degraded soil in the mid-row of long-established vineyards is being investigated by John Crocker, senior research officer at SARDI. Literally “groundbreaking” research on the injection of flowable compost to depth during deep-ripping operations will seek to demonstrate the value of this method for improving vineyard soils.
The project uses an innovative prototype ripper (subsoiler) developed by the Agricultural Machinery Research and Design Centre at the University of South Australia. The new ripper differs significantly from conventional equipment and requires less horsepower to penetrate deeper into the soil profile, even under dry conditions. Initial testing has proven the ability of the machinery to create a vertical band of compost within the soil profile alongside the vines. Compost injection using the prototype ripper requires a two-pass operation. In the first pass, the oscillating tines fracture the soil profile to a depth of 550 mm to 600 mm. This creates a loosened zone for compost injection and provides potential pathways for later root growth and moisture infiltration.
On the second pass, the ripper tines are fixed, and compost is delivered down a tube at the back of the ripper tine in a powerful air stream. Continuous, vertical bands of organic matter approximately 50 mm wide could be created by the ripper system at 800 mm out from the vine row to depths of 500 mm to 600 mm in dry, compacted vineyard soils. The new machinery offers a powerful tool to investigate the value of soil-injected amendments under small-scale experimental conditions.

Orchards
Research being undertaken by SARDI’s Integrated Pest Management (IPM) team to develop better ways of controlling Kelly’s citrus thrips (KTC) is being supported in-kind by the Compost for Soils program. Peter Crisp, a SARDI senior researcher, has identified that beneficial predatory mite populations increase when soil carbon is increased as a result of compost application. Mites can be important beneficial predators, and in citrus they work to control the major pest KCT, which causes blemish on fruit leading to the downgrading of produce and losses to the national industry of approximately $10 million annually. These losses include the costs of chemical application – currently the only option for KCT control once an outbreak exists. Predatory mites are the main enemy against KCT pupae in the soil. When these mites are in high numbers, they can reduce the number of KCT emerging from the soil by at least half. A key ingredient for success of the mite populations is compost. Several different composts have been evaluated and all have been found to increase mite numbers.
To assess the economic feasibility of compost applications, the effects of compost on other aspects of citrus production are being measured as part of SARDI’s research program. Yield increases from 10 percent to 50 percent have been recorded, with the level of increase affected by compost type, application rate and orchard location. “We were amazed at the yield improvements we recorded – they were way above our expectations,” says Crisp. “Increases in yield were due to higher fruit density on the trees as well as increased fruit size.”
Fruit size increased by 4 mm to 7 mm on composted trees, the extra millimeters adding approximately $100/metric ton to the value of the fruit or about $13 million in South Australia or $55 million annually nationally when applied to current yields. First year improvement in net return is estimated at $4,500/hectare (using three trial orchards in the Riverland), and this return is expected to reach at least $10,000 in subsequent years when compost applications aren’t needed. An additional benefit of compost application included increased water efficiency, with soil moisture rates under composted trees approximately 25 percent higher than under trees without compost.

The Road Ahead
Such high-quality research and positive results give the Compost for Soils program additional weight to lend to its market presence and education campaign. The program has managed to pull together state and national government funding, three major compost processors and top-notch SARDI researchers. Compost for Soils now has been adopted nationally and covers using recycled organics on sporting fields, roadside landscaping, degraded land, community parklands and council parks and gardens as well as for commercial horticulture and agricultural applications.
“Compost for Soils has played a major role in demonstrating how professional our industry has become,” Jeffries says. “We’ve done 80 percent of the hard yards in building solid relationships with our clients, and in the last 6 to 12 months the momentum has been building. Our sector is growing and definitely heading in the right direction. Adopting this program nationally is another step forward.”
The Jeffries Group and its two competitors-turned-collaborators – Peats Soil and Garden Supplies and Van Schaik’s Biogro – were recently recognized with an award from Compost Australia and the Waste Management Association of Australia. The Compost Leadership Award acknowledged their contribution to national market and industry development. “It’s great to have our initiative acknowledged, and we’re proud to be recognized in this way,” says Lachlan Jeffries. “It is rare in business for competitors to work so closely together, but we all saw the need to take our industry to the next level.” For more information visit www.compostforsoils.com.au.

Angela Lush is director of Lush Logic, a specialist science communication company. She has an undergraduate degree in agricultural science, PhD in ecology and more than 10 years experience in agricultural research.