Cutting costs with household compost

They say that one man's trash is another's treasure - and crops gracing paddocks around the Wheatbelt are the living proof.

Compost made from household rubbish collected from Perth is finding a new home in WA's agricultural landscape and there are hopes it could provide a win-win solution for both croppers and the environment.

Jason Chittleborough, a Brookton farmer and owner of composting company Nutrarich, has been collecting more than 20,000 tonnes of the compost from the Regional Resource Recovery Centre (RRRC) in Canning Vale for three years.

He said rubbish was collected from the green bins in the Southern Metropolitan Regional Council and then taken to the RRRC, where it goes through a digestion process - or is ground into small particles - for three to five days.

Large particles such as metals and plastics are removed, but otherwise everything from household scraps to garden clippings and paper then spends another 28 days being composted using an aerated method.

It is then put through a 5mm screen before heading to Mr Chittle borough's facility.

From there it can either go straight onto farmer's paddocks for a minimal cost, or be further composted to create a more complete product.

Pingelly farmer Tim Lange has been applying compost directly from the RRRC for two years and said although it's too early to see concrete benefits, he's excited about the product's potential.

The first year, in 2010, he applied the compost at a rate of 3.12 to 3.75t/ha before planting and later applied 25kg/ha of urea, but he admits it wasn't enough nitrogen.

"Compost was detrimental if anything because nitrogen was being taken out of the soil to break down the compost," Mr Lange said.

"The following year we added more nitrogen (70kg/ha of urea) to the soil when we seeded, which gave the microbes food essentially.

"That's all we used, we didn't use any compound fertiliser, only urea so the input costs were lower. The plants certainly looked vigorous and happy.

"There was no increase in yield and I'm not expecting that because I'm not putting the inputs in.

"The idea isn't to necessarily get an increase in yield, but to use fewer inputs, so therefore your breakeven point should be lower."

This year he ran out of time to add compost to the areas he sharecrops.

Mr Chittleborough said if the material was further composted the nitrogen draw down would be reduced, but in the meantime the material provides some benefits.

"Not only do we have a pH neutral product, it has potassium, phosphorous, manganese, copper and zinc," he said. "The product isn't soluble and doesn't travel in the soil like soluble fertiliser."

That means the compost could be a more environmentally friendly fertiliser by reducing runoff while improving the soil's structure and organic matter.

In the meantime, it's reducing the amount of landfill in metropolitan areas and sequestering carbon.

It's already showing some impressive results when used on salt scalds, but both Mr Lange and Mr Chittleborough concede more research needs to be done on the product.

Mr Lange said he had hundreds of questions about the long-term impacts of the compost, which could only be answered by comprehensive trial work.

"I see the benefit of it in improving the structure of our soil and not having to rely on chemical fertilisers," he said.

"I'm guessing by doing what we're doing we're going to start seeing mushrooms come back in the paddocks.

"But I'd love to see trials based on the raw product versus fully mature compost - how that would perform and then the effect it has on the soil structure over time.

"Is integrating it with the soil going to be the best thing? The whole lot needs more trial work."

Mr Chittleborough has been applying the product on his pasture paddocks for five years and said he could see a marked difference, but without further trial work the wide-scale benefits of the RRRC compost could not be realised.

In a climate where the industry is being encouraged to move towards becoming carbon neutral, Mr Chittleborough said it was more important than ever to start thinking outside the box.

"I see (the product's) future as a complementary input that replaces or at least reduces your need for large amounts of fertiliser and lime," he said.

"Ultimately we could eliminate the need for liming in your paddocks.

"In this climate it's a carbon-based fertiliser, so if we could trade it would be an offset for a farmer.

"We could actually, if we had further assistance from the State Government through the landfill levy, make it into a pelletised, formulised fertiliser that goes down the airseeder.

"The scope of how much waste could come out of Perth based on this model, Perth couldn't supply the agricultural sector's demand. Waste will always be with us."