The salmon industry in Tasmania is expanding, and that means more waste from fish farms to manage.
Five southern farms are taking part in a special trial in which fish waste is being used to revitalise soil.
The waste — excrement, heads and guts — is converted into liquid form for spraying on selected paddocks.
Will Chapman's Derwent Valley property is the "guinea pig" for the trial so far, and despite the odour, he's excited by the results.
"It's been worth the couple of days of curious nose smells to have a vast improvement in the soil nutrient levels," said Mr Chapman.
"We have spread 60 truckloads, which is over a million litres onto our paddocks, and the pastures are coming up much brighter and more vigorous.
"It's certainly something we are pretty excited about and it's a great project for regenerating pastures that have been barren."
Promising results
One of the three big salmon processing companies, Huon Aquaculture, is supplying the solids from its farms and hatcheries.
Environmental manager Adam Chapman says the trials are being carried out under strict requirements.
"Biosecurity Tasmania, the EPA and the local councils all have to approve the trials and they test all the product we supply," Mr Chapman said.
"There is constant soil sampling and ground water monitoring to make sure there is no leachate into any streams or waterways.
"As the salmon industry gets larger, the waste volumes are increasing.
"In Europe they actually sell this waste stream to farmers."
Josh Tomlin, from Tasmanian family-owned company Spectran, which is managing the trials, says the results are promising.
"The soil testing has shown high levels of nutrients like phosphorous and nitrogen, and the growth of crops and grass is noticeable," he said.
"There is a big visual difference between a spread and a non-spread pasture, and the nutrients are a slow release form into the soil with no flush.
"The logistics of spreading the fish farm waste has its challenges, as it comes in a heavy liquid form and we are using a 300-horsepower tractor."
Mr Chapman says the trials are a win-win for the farming industry and for the aquaculture industry, and believes spreading the waste will become common practice.
He also believes the process will be cost effective for farmers across the state.
As for the odour issue, Mr Chapman describes it as the smell of a healthy backyard vegie garden and says it disappears quickly.
