Compost as catalyst?


Compost is not only for domestic and agricultural use. WRAP’s Landscape and Regeneration programme has been applying compost with recycled materials to makeover brownfield land for the last few years.

The organisation’s ‘trailblazers’ have set a standard and provide an example of best practice in this area. But what are they, and how can local authorities benefit from such a scheme?

Paul Mathers, Programme Manager of Landscape and Regeneration at WRAP, explained: “Over the last few years we worked with a number of universities and did a large amount of research with case studies using compost. We had to build a body of evidence to local authorities that compost was fit for purpose.”

One such trailblazer project of compost usage was for Sunderland City Council on a heavily contaminated site: the former Lambton Cokeworks in County Durham. PAS 100 Compost was used on the land - which forms part of the National Coalfields Regeneration Programme. The project involved initial soil remediation of the existing topsoil and decontamination of the site.

As the developers wanted to avoid the costly import of topsoil and export of contaminated materials, as well as addressing the shortage of available soil reserves, compost made from recycled green waste was specified.

Mathers said: “Waste from the paper industry was used in the compost. It’s about local authorities recycling their material as compost.”

Dr Robin Davies, soil scientist for the project, explained: “Green waste compost was the best form of organic matter to manufacture soil with. It is best physically and in relation to plant nutrients - especially for indigenous woodland, which makes up a large proportion of the site.”

Imported paper mill crumb and colliery shale used for soil underwent tests to make sure it complied with the Contaminated Land Regulations 2000, and could be mixed with green waste compost to form a suitable subsoil.

Mathers explained the application of compost: “A light touch compost was trialled. There was a lot of local species and biodiversity in the area and they wanted to encourage this.

“The approach worked; it encouraged biodiversity without using grass. Ecological concerns were managed successfully.”

Mathers was also keen to point out the financial benefits of the scheme: “They saved about £1.2 million - cutting back on the costs of fertilisers and pesticides.”

So why aren’t more local authorities taking advantage of WRAP’s service? “It’s the unknown,” Mathers continued, “once they have the evidence, they give it a try.”

The cost savings doesn’t mean that quality is compromised though: “We push the quality of the compost. We need to meet local authorities to show how, and why, it works,” Mathers said.

Another project was undertaken by North Somerset Council, using compost mulch to reduce weed cover and enhance tree growth.

Mathers said: “We knew compost would suppress weeds - in trials it showed a 50 percent reduction. So now it has been rolled out.”

What about maintenance of newly regenerated sites? “There are short term and long term consequences.” Mathers said. “Compost, because of its nature, there are no weeds in the first two years. However over the next three years, there is some maintenance.”

And what of the future? “Increasingly,” Mathers said, “food waste will be collected. At the moment it is not sustainably recycled. There is a big push by Government though.

“We have done a number of studies, and it is the same again, have to demonstrate to local authorities how successfully it works.”

Summing up, and going forward, Mathers feels the results speak for themselves: “It’s early days yet but we are seeing results.

“2.7 million tonnes of waste collected in 2007- 08 was used as compost. Half went to agriculture, but the regeneration market is growing. When it comes to sustainability, all local authorities want to be sustainable.”

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