Cow shed effluent converted to fish food – public open day
Wednesday, 17 February 2016 10:00 a.m.
DairyNZ and Bay of Plenty Regional Council are joining forces to host a public open day on a dairy farm near Katikati to demonstrate the on-farm trial of a process to convert dairy shed effluent into fish food.
The innovative project, jointly funded by the Bay of Plenty Regional Council and Ministry for Primary Industries Sustainable Farming Fund, is working to convert nutrients from dairy shed effluent into algae and zooplankton that can be used to feed fish. This conversion process continues within the farm drains, with the additional benefit of converting run-off nutrients from pasture.
In mid-2015, the physical works for the three-year trial were completed and the facility started operation in December.
Regional Council Rivers and Drainage Manager, Bruce Crabbe, said that the potential implications of the project for farmers around the country were huge.
“It is still early days for the project and this is an opportunity to show members of the public the newly-built ponds and explain what the project is working to achieve. If everything works as it should, we expect to see improved water quality in the drainage system and an increase in numbers of fish species such as tuna (eel), inanga (whitebait), and mullet.
“Dairy effluent is currently used as a liquid fertiliser around New Zealand and this trial is considering an innovative alternative use. This interesting solution could see dairy farmers, aquaculturalists, and the environment benefit from a new use of existing technology.
“A successful trial will provide options for resilient and sustainable farming systems that reduce nutrient loss, improve water quality and aquatic habitats, and provide additional income from aquaculture,” Mr Crabbe said.
The trailed system uses dairy effluent at the bottom of the food chain, providing nutrients to promote algal growth in purpose-built High Rate Algal Ponds (HRAPs) developed by NIWA. The algae is settled and harvested in the Algal Harvest Ponds (AHPs) then piped in slurry form to a separate zooplankton pond constructed within the farm drainage system. Zooplankton (minute shrimp-like crustaceans) in this pond feed on the algae and grow to provide a live food source for fish. With the consistent availability of an abundant and nutritious food supply, fish will be encouraged into the farm drainage system from the Aongatete River through a fish-friendly passage.
The public open day will be held on Wednesday, 24 February 2016 near Katikati to show interested parties around the trial site and explain the projects goals.
For more information and to register for the open day visit www.boprc.govt.nz/dairyeffluentconversion
Media are welcome to attend the open day near Katikati. Please contact Abby Tozer (details below) for details on location and what to bring. BBQ lunch will be provided. There will be photo opportunities and subject matter experts available for comment on the day.
High resolution photos are available on request. Further information and some images are available at www.boprc.govt.nz/dairyeffluentconversion
Funding is provided by the Ministry for Primary Industries Sustainable Farming Fund and the Regional Council's Bright Ideas Innovation Fund. The Fund was established in 2010 to help fund innovative staff projects and ideas that are likely to improve the value of the Regional Council's work in the community, but which fall outside standard work programmes.