Incentives for Change

Study Shows Dairy Farm Work is Helping Improve Water Quality

The implementation of Good Management Practices on-farm does improve water quality, proves new research that analysed water quality trends over 20 years.

Riparian planting. Photo: DairyNZ

New scientific data highlights the success of dairy farmer and wider sector efforts to improve surface water quality in New Zealand.

As part of an Our Land and Water study to analyse historical data, DairyNZ’s environmental science team, in collaboration with AgResearch and Lincoln University, has revisited dairy farms in five catchments to assess whether on-farm actions have helped improve water quality over time.

The five catchments – Waiokura (South Taranaki), Toenepi (Waikato), Waikakahi (Canterbury), Bog Burn (Southland) and Inchbonnie (West Coast) – are dairy farming areas that were part of the 2001–2010 Best Practice Dairy Catchments project, which monitored water quality and environmental work on-farm. 

Researchers found that, over the 20-year monitoring period, 67 percent of in-stream water quality trends across the five catchments were improving, and the levels of most contaminants in water have decreased due to farmers implementing good management practices (GMPs) such as improved effluent management and stock exclusion.

The study found that in-stream concentrations of phosphorus and suspended sediment decreased the most in response to on-farm work.

Overall, the research shows the implementation of GMPs on-farm does improve water quality.

DairyNZ general manager of sustainable dairy, Dr David Burger, says the analysis shows the positive outcomes achieved by improving management practices on dairy farms.

“The mitigation options dairy farmers can take to reduce footprint are widely known, but analysis of the positive impacts of these over time is less available. So it’s positive to see this dataset showing that extension efforts to help farmers improve their management practices have led to water quality improvement.”

Research lead and Our Land and Water National Science Challenge chief scientist Professor Rich McDowell says the findings are positive but also show continued action is needed in key catchments to maintain the momentum.

“The data shows that, over the 20-year period, many trends were improving or showed no change. However, we know nitrogen levels increased in many catchments due to development on other dairy farms over the same period.

“This means there is still more to do in some areas to lower nitrogen and E.coli concentrations. In some catchments, more than good management practice may be required, such as land-use change, to meet water quality expectations,” he says.

“DairyNZ continues to work with farmers to develop on-farm practices, provide a scientific evidence base to help inform practical and fair regulations, and demonstrate the positive results of the actions farmers are taking to improve the health of our waterways.”

Farm environment plans identify actions to improve water quality, reduce greenhouse gas emissions and increase biodiversity, and are tailored to individual farms. Currently, more than 70 percent of New Zealand dairy farms have farm environment plans and 45 percent have greenhouse gas farm plans. By 2025 all farms will have both plans. 

“The dairy sector is committed to sustainable dairying and farming within environmental limits,” Dr Burger says. “Through the Dairy Tomorrow Strategy and other work, DairyNZ, dairy companies, sector partners and research organisations are reinforcing the value of GMPs and supporting farmers as they continue to improve their systems to achieve environmental outcomes.”

The full research findings have been published in the Science of the Total Environment journal. The research was funded by the Our Land and Water National Science Challenge.


Justine McLeary

Justine McLeary is DairyNZ's senior media specialist

One Comment

  • Nga Kaitiaki o nga Wai Maori (NKONWM) is a collective of 5x hapu from the upper Wairua sub catchment near Whangarei. We are neighboring hapu who hold mana I te whenua around the Hikurangi Repo, once the largest wetland in the southern hemisphere, now the source of highest dairy yield in Tai Tokerau, to the tune of $39 mill/ yr. NKONWM have been monitoring water quality in the Repo for 7yrs now, with Living Waters, now de ceased, eg no longer operational partnership between Fonterra and DOC. While there are many issues about the Repo and its degraded water quality, the most pressing one for hapu kaitiaki, is low to no dissolved oxygen throughout the almost 6,000 ha of the Repo scheme.
    As we work with many stakeholders, including farmers, Fonterra, Whangarei District Council who own a no longer fit for purpose, flood management system of 7x pump stations that obstruct and have been killing migrating tuna for almost 70yrs, Northland Regional Council, etc, the downstream impacts are enormous. We want to find ways to improve water quality, by improving oxygen levels, reducing sediment while reviewing and future proofing local land use in the Repo. PCE Simon Upton is currently completing research paper on sustainable economic options in the Repo, however those compete with the high dairy yield from current dairy farming practices in the Repo.
    NKONWM are also part of a project to present a Business Case of options for the future of the redundant Repo flood management scheme, as it currently is. There remains a high need to correlate an effective flood management programme, for local farmers, as well as protect downstream flooding and sediment impacts to the Kaipara Moana catchment. While there is a significant investment into Kaipara Moana Remediation (KMR) programme, there is little evidence of at scale positive change to reducing the key sediment load being delivered to the Kaipara Moana, inspite of the sizeable investment. Tribal political barriers and exclusion of hapu from upper Wairua sub catchment being at the decision making governance table, as well as, single focused riparian planting strategies that target farmers/land owners not communities, are reflections of old Regional Council led advisors small thinking that misses the biggest generator of sediment – the Hikurangi Repo.
    While there is no specific action to address the low to no oxygen levels throught the Repo, NKONWM believe already endangered taonga species are under even greater threat.


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