The use of human biosolids to improve pastures has been catching on in New South Wales – to the point where demand for the resource from area farmers is outstripping Sydney Water’s available supply. Each year, the company reuses 100 per cent of biosolids produced, for a total of approximately 180,000 tonnes.
“The soils on our farm are of poor quality and fragile, with low organic matter and poor structure – which makes pasture improvement difficult,” said NWS sheep farmer, Gordon Nash. “Conventional fertilizers were only providing a short-term positive effect – with no ongoing benefits.”
Nash, who runs Australian Merino sheep at his ‘Ulabri’ property at Wattle Flat near Bathurst, was able to see first-hand the results other farmers were seeing after using biosolids on their crops. According to Nash, it was an “easy decision” to make the switch.
“We now have better water retention, the ability to graze our sown paddocks earlier, and consequently, improved production per hectare,” he said. “Our wool production per sheep has grown … and our young sheep growth rates have improved, which in turn leads to heavier body weights for our sale sheep.”
When used as fertilizer, biosolids enrich soils with nutrients and organic matter, providing increased moisture retention. This year, Nash said his farm is experiencing a dry spring – but the pastures that have been treated with biosolids are still providing the sheep with sound grazing forage. The unimproved pastures, on the other hand, are “struggling,” he said, due to the conditions.
According to Gavin Landers, Contract Plants Manager at Sydney Water, the process also has a broader positive impact on the environment. Around 21 percent of the total energy produced by Sydney Water comes from the process of digestion used to generate biosolids – providing enough energy to power the equivalent of more than 11,000 homes each year.
“Capturing and treating biosolids also protects Sydney’s waterways and the ocean, allowing the transformation of what was traditionally a waste product into a valuable resource,” he said.
Thirty years of Australian and international research has concluded that when managed correctly, the application of biosolids to land has no adverse impacts on the environment or human health. Only certain crops can be grown on land treated with biosolids, including cereals and grains which never come into contact with the biosolids. All crops are processed carefully once harvested.
The collection, transport, storage, and beneficial use of biosolids themselves is also heavily regulated by a set of established guidelines and processes. To remove toxins and bacteria, Sydney Water screens and settles the sludge before baking it at high heat for two periods of twenty days or more before it is transported for reuse on farms as biosolids.
“All biosolids produced are subject to strict product analysis at accredited laboratories,” said Landers. “This analysis grades the biosolids so that they are fit for purpose in the market.”
The guidelines provide strict protocol on how the biosolids must be spread on farms, as well. Regulations stipulate that producers must wait a period of at least 30 days before stock animals are allowed access to the land.
For Nash, this initially posed a bit of a challenge. Accommodating the contract requirement that biosolids be applied to forty hectares of his land per year meant tying up a large portion of pasture during the application and sowing process – somewhat difficult with a herd of livestock to graze.
However, now that the treated land is showing to be significantly more productive, Nash said it was well worth the temporary disruption.
“My advice to other producers who are considering biosolids is to not think about it for too long – just get it,” he said. “Get on a biosolids program, as it is dynamite.”