WHILE human waste may not be a palatable subject to some, the Wilksch family at Yeelana are embracing the by-product in an attempt to improve their poorer soils.
Biosolids are an organic resource recovered from wastewater. It is extensively treated to reduce water content and pathogen levels to meet regulatory requirements and is safe for use.
Randall Wilksch was a guest speaker at last week’s Getting the Crop In seminar at Clare, where he outlined how and why they used biosolids in the past two years.
“My brother Jordy was researching alternative fertilisers to improve poorer areas of paddocks,” he said.
“He looked into tuna compost, but there wasn’t enough available locally, and chicken litter, but it wasn’t viable to freight to the EP.
“Then he came across biosolids offered by the Bolivar Wastewater Treatment Plant.
“It was a free soil conditioner that farmers had trialled in other areas of SA and it was granulated, so we could spread it without having to buy new machinery.”
SA Water says a 5 tonne a hectare biosolids application provides about 60 kilograms/ha of phosphorous; 60kg/ha nitrogen; 30kg/ha sulphur; 195kg/ha calcium; 4kg/ha magnesium; 4kg/ha zinc; and 3kg/ha copper. It can also contain arsenic, nickel, cadmium, lead and mercury, but only biosolids with suitable levels of metals are approved for reuse in farming.
Randall said despite the nutrient levels, biosolids would not be counted in their fertiliser program.
“We are focusing on its carbon aspect,” he said.
The family trucked in 150t of biosolids last season and spread it at a rate of 8t/ha.
“We use the biosolids on acidic, buckshot gravel loams,” Randall said.
They have applied it at the same rate on another paddock this season, spread with gypsum and/or lime.
It is incorporated into the soil up to 400 millimetres using a Kuhn deep ripper with discs and crumble rollers.
“The soils are acidic on top, but alkaline in the clay underneath,” Randall said.
“We’re trying to pull that clay up, but it’s a fine line – the clay is sodic, which we manage with gypsum, but it can also be toxic if we pull too much through.”
There are requirements when using biosolids, including a 10t/ha a year maximum application rate, avoiding water sources and sampling soils prior to use to ensure they can hold the product.
“People need to be mindful when using biosolids as it is a human waste product and you do have to be careful, but it’s not anything major. No hazmat suits required!” Randall said.
“There is also public concern about the safety of using biosolids in food production, but we're not spreading it on growing plants, it’s being incorporated into the soil.”
As to on-farm results last season, Randall said there wasn’t a significant difference because the trial paddock, sown to Mace wheat, fell over during the superstorm last September.
“But we weren’t expecting immediate results anyway – this is part of a long-term process,” he said.
This year, that wheat paddock will be sown to faba beans, while a new biosolids-treated paddock will be sown to lentils.
“We’re hoping that where we yielded 0.5t/ha lentils last year, we can lift those poorer soils to perhaps 1.5t/ha, making it a viable option,” Randall said.
Randall, with wife Julie, parents Max and Julie and brother Jordy with his wife Kylie, and employees Fred Gerber, Sam Carmody and Matt Haylock, crop 3650ha of wheat, canola, lentils, lupins, faba beans and barley.
They aim to start seeding in the week before Easter.
Alisha Fogden
Journalist at Australian Community Media newspapers since 2007.
Journalist at Australian Community Media newspapers since 2007.
