Small wetland, big difference

A wetland built three years ago on Donna and husband Philip's Awatuna, South Taranaki, farm is a collaboration between DairyNZ, the National Institute of Water and Atmosphere (NIWA) and Taranaki Regional Council (TRC). It is part of DairyNZ's ongoing work to encourage farmers to understand the environmental benefits of wetlands.

Wetlands can significantly reduce nutrient and sediment losses on farms and improve water quality. They also boost biodiversity and can provide habitat for birds and fish.

DairyNZ general manager sustainable dairy, Dr David Burger, says there's growing interest among dairy farmers in re-establishing and construction wetlands, and this project helps improve understanding of how well they work.

"Partnering with dairy farmers and sector organisations helps us improve practical guidance around the use of constructed wetlands and how they can support the drive towards water quality improvements," he says.

NIWA and TRC are monitoring the performance of Donna and Philip's wetland to remove nitrogens, phosphorus, sediment, and E. coli. DairyNZ funded the installation of monitoring systems, which enable real-time measurements of flow and water quality as the wetland inlet and outlet.

The project started after initial discussions between Donna, Philip and TRC, which then approached NIWA for advie and assistance with design. The project grew because, it turned out, NIWA was collaborating with DairyNZ to produce guidance on constructed wetland design and performance, to give the rural sector tools and resources to help improve environmental outcomes.

The Cram wetland has become one of six constructed wetland demonstration sites being studied until June 2024 as part of a collaborative, NIWA-led initiative funded by the Ministry for Primary Industries.

"NIWA staff looked at our farm and where the slopes and run off were, and came up with the site, which was an old, adjusted stream," Donna says.

The wetland comprises two percent (0.45ha) of Donna and Philip's 117ha farm and receives surface and shallow groundwater from 184ha of land. "It's a nice place to be, with amazing views of Mt Taranaki," Donna says.

"We have a path round half of it and it and later on we'll do it all the way around. We have a bit of regenerating bush at the bottom of the wetland that was inaccessible for animals, so there is quite a lot of change happening in that area of the farm."

Dairy farmers around New Zealand are focused on continuing to reduce their environmental impact. Dr Burger says DairyNZ continues to work closely with dairy farmers and other science organisations to increase understanding of wetland performance.

"We are committed to improving water quality and have an extensive range of work underway to achieve this goal, in line with the sector's Dairy Tomorrow goal of protecting and nurturing the environment for future generations."