First hemp crop trial at sewerage works completed

One of Australia’s first hemp crops grown to test it’s ability to soak up effluent from a sewerage treatment works has just been harvested. The crop could provide an ecologically-preferable alternative to dumping sewerage in rivers and the ocean nationwide.

The one-hectare industrial hemp crop was grown at a sewerage plant near Byron Bay on the NSW north coast between November and early February, by Dr Keith Bolton from Southern Cross University (SCU), in collaboration with Ecofibre Industries Ltd (EIL), and Byron Shire Council.

Brisbane-based EIL, who provided the industrial hemp seed and agronomic support, have been involved in breeding hemp for Australian conditions, and successfully lobbying for legislative changes at a state level to allow commercial hemp crops.

The project is a continuation of SCU’s North Coast Mop Crop Project trialing various crops to ‘mop up’ effluent.

“This is our biggest hemp mop crop project ever and the first time we’ve grown a hemp crop in association with a public sewage treatment works,” project leader Dr Bolton said. “It’s about turning effluent into affluence, or waste water into resource water.

“Mop crops often represent a better alternative to dumping effluent into creeks, rivers and oceans, which poses a serious threat to the health of aquatic ecosystems.”

Another hectare at the sewerage treatment works was planted with bamboo and kenaf. Kenaf and industrial hemp belong to a group of plants which produce ‘bast fibre’, used in paper, plastics, building materials and textiles.

The crops will be used for trial processing for future development of the bast fibre industry in Australia, Dr Bolton said.

Researchers in SCU’s School of Environmental Science and Management will analyse the three crop species to see how many nutrients, such as nitrogen and phosphorus, they take out of the sewerage.

“We will measure the total mass of the crop, then analyse the foliage and the stem to see how much nutrients are stored in them, compared to how much went in via the sewerage effluent,” Dr Bolton said.

Whenever large amounts of effluent were disposed of, there would always be some negative impact.

“I believe that land-based effluent reuse has a lower impact than river dumping, and we’re looking carefully at the impacts on the groundwater and soil,” he said.

“This experiment is crucial to the future of mop crops on the north coast, as it will help us to determine how much effluent we can sustainably use in a mop crop.”

Dr Bolton is the pioneer in Australia of growing hemp to soak up sewerage. This is his third such project and he intends to expand further. He grew an industrial hemp crop at a piggery near Casino in 2003, and the year before tested the idea with artificial effluent on his property at Jiggi near Lismore. The crops were all grown under license from the NSW Health Department.

Legislation is rapidly changing to allow larger scale commercial crops of the low-THC variety (which do not give users a ‘high’) to be grown in Australia. Commercial crops can already be grown in Queensland, Victoria and Tasmania, and look set to be allowed in NSW next year.

“We feel hemp is the crop of the future and we intend to be there at the ground floor,” Dr Bolton said.

Other Mop Crop projects Dr Bolton is involved in include: the planting of 600,000 paperbark trees in a cleared wetland area irrigated with sewerage from the adjacent Byron Bay sewerage treatment plant; and the Coffs Harbour Banana effluent reuse project, where effluent is being used to irrigate banana plantations as an alternative to an ocean outfall.

“We use different mop crops for different situations,” he said.

Contact: SCU Media Liaison Sara Crowe Ph: 6620 3144 or Brigid Veale Ph: 6659 3006.