Farm trials show next-gen compost benefits for vegie growers

Senior Land Services Officer Peter Conasch from Greater Sydney LLS, comparing root development in crops grown in compost (left) and chicken manure (right); field walk at the Greater Sydney LLS Demonstration Farm.
Senior Land Services Officer Peter Conasch from Greater Sydney LLS, comparing root development in crops grown in compost (left) and chicken manure (right); the compost project team at the Greater Sydney LLS Demonstration Farm.
Greater Sydney Local Land Services (GS LLS)

The Greater Sydney LLS Demonstration Farm, on the Richmond campus of University of Western Sydney, showcases innovation and best practice in horticulture, irrigation and mixed farming. 

A recent focus of the farm, which is managed by Greater Sydney Local Land Services (LLS), has been to demonstrate the value of recycled organic compost in vegetable production by comparing different compost soil treatments with conventional farmer practices.

These compost trials have been overseen by Peter Conasch, a Senior Land Services Officer with Greater Sydney LLS, who draws on 20 years of agronomic experience.

The trials formed part of a larger project with NSW Farmers and University of Technology Sydney’s Institute for Sustainable Futures (ISF) that explored the demand potential for recycled organics compost in NSW’s commercial vegetable cropping sector.

The project was one of several recipients of funding from the NSW Environmental Protection Authority (EPA) under its ‘Waste Less, Recycle More’ environmental market grants scheme.

The farm’s role in the project, explains Conasch, was to demonstrate the benefits of adding a high-quality recycled organics compost at different concentrations to soils used to grow trial vegetable crops.

The trials set out to show that next gen compost-grown vegetables could produce similar or better yields than current farmer practices of using inorganic fertilisers or chicken manure. The next gen blend iwas augmented with a slow-release nitrogen fertilser  to offset the nitrogen drawdown described in previous studies that suppresses yields.

“By applying various rates of compost (or treatments), we wanted to further understand and document what the benefits were in terms of yield, plant health [and] soil structure as well as water-holding capacity,” Conasch says.

About the trial plots

The GS LLS project team, helmed by Conasch, ran compost trials on plots at the Greater Sydney LLS Demonstration farm near Richmond. 

“We used a compost which was made to Australian Standards and well pasteurised,” says Conasch. “Sourcing the product from a reputable supplier was critical.”

The compost was spread “evenly and accurately” over the trial plots (‘treatment areas’) and incorporated thoroughly into the soil. Three different levels of application were used: 10 tonnes of compost per hectare; 15 tonnes/hectare; and 25 tonnes/hectare.

Capsicums were grown on the plots over the summers of 2015/16 and 2016/17. A separate plot was used to grow a corn crop under similar treatment conditions.

Each treatment plot was monitored carefully and results were recorded throughout the project period.

Key findings

One of the most apparent benefits of recycled-organics compost application was a distinct improvement in the soils to which compost had been applied.

“We noticed a significant difference in the overall appearance of the soil,” says Conasch. “Structurally, the soil had significantly improved.”

The project team also noticed improved plant health and root development, and – importantly, increases in soil-borne bacteria, an indication of healthier soil. 

The comparative trials also showed a number of negative effects from growing plants in chicken manure under current rates and practices.

The farm demonstration of corn grown under different soil treatments showed that a 50:50 mixture of poultry manure and compost supplies enough nitrogen to satisfy drawdown and improve the supply of phosphorus, which is too high in poultry manure and too low in compost.

Moreover, the corn trials indicated that the compost-chicken manure blend outperformed inorganic fertiliser.

“Ongoing compost use will certainly be implemented into our cropping practices,” says Conasch.

“The benefits are very visible and we would strongly recommend its use.”

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