The “Dairy best practice catchments” project was established in the early 2000s under DairyNZ’s predecessor body Dexcel as an initiative working with commercial farmers that evolved into a focus for researchers as dairying expanded through the following decade.
After DairyNZ moved to more farm-focused research, the projects were picked up by NIWA and regional councils, spanning five areas from Bog Burn in Southland to the Hauraki Plains.
NIWA’s head freshwater scientist Dr John Quinn said researchers had been concerned about whether the studies would continue to get funding, given their nature and length of study period.
“It is always difficult to get long-term work funded, and even more so in many cases when it is environmental research being conducted.”
The research programme had been funded out of a contestable pool of funds.
But the Budget’s Strategic Science Investment Fund (SSIF) specifically incorporated strategic freshwater research with $63 million spread over four years for that work.
Quinn said the funding certainty was also welcome because researchers had built up strong, long term relationships with landowners in the five areas, providing constructive, actionable feedback to scientists.
“There is an element of ‘learning by doing’ and we need things at a farm and small catchment scale to fully understand how farms function in them before moving to larger-scale work and plans.
“The freshwater research space has had a lot of contestable funding in the past and this is not so much an increase in funding but in certainty of funding, it enables us to maintain freshwater research.”
Study of nutrient flows requires relatively significant timelines to measure changes and Quinn said the projects were already revealing some valuable trends.
Specific management practices that fit the local situation were developed for each of the five dairy best-management catchments.
In the case of Bog Burn, which drains into the trout-rich Oreti River in Southland, researchers identified combinations of approaches involving deferred effluent irrigation, low-rate effluent application, riparian planting, raceway runoff control, treatment wetlands, cow wintering strategies either off-farm or herd shelters, lower/optimised fertiliser rates and (initially) DCD nitrate inhibitors to lower the losses into the catchment and improve stream habitat.
“From this we were able to offer a package and the ability to link them and determine the ability to improve losses by taking different options.”
Across all five catchments since the project began there had been a decrease in suspended sediment concentration for all streams, generally increasing water clarity, and lower E. coli concentrations in three of the streams. These were attributed to improved stream fencing that excluded cattle and greater use of irrigation for treated effluent disposal, with less reliance on pond systems discharging to streams.
“Looking at the trends in pastoral stream water quality nationally over the last 10 years, we have seen significant improvement in phosphorus and ammonia levels, but nitrate has generally got worse.”
“Long-term monitoring, linked to knowledge of farm practice changes, is needed to detect responses to newly legislated requirements for improved water quality and identify how to achieve these cost-effectively”.
