Robust science the most effective tool in protecting water quality

Improving water quality is DairyNZ's goal.

As part of our work to enhance and protect water quality, DairyNZ's team of environmental scientists, policy advisers and sustainability specialists is taking a solutions-focused approach to help farmers and the sector meet environmental limits and improve water quality.

Robust science is at the core of this environmental stewardship programme to help ensure solutions are evidence-based, practical and will achieve and exceed the required catchment limits set by local government.

That means using your levy to ensure that we deliver science and tools that give confidence that any required changes and investment on-farm are sound, tried and tested.

To achieve this, DairyNZ is working in partnership with regional councils, crown research institutes, universities and other industry science providers, to provide the best peer-reviewed science in a transparent way.

Underpinning our approach is the need to understand what drives water quality and what makes it change. For example, if we want to reduce nuisance slimes or algae, should we target nutrients, flow, or shade? If we focus on nutrients as a solution, which ones should they be and what is required to achieve desired outcomes?

We also want to understand which on-farm solutions will best meet specific water quality targets and how these differ across landscapes, soil types, climates and farm systems.

For example, projects under way are testing the performance of constructed and seepage wetlands, wood chip bioreactors at the end of tile drains, and riparian buffer effectiveness on critical source areas. These tools can help in reducing farm nitrogen, phosphorus, sediment and faecal bacteria losses, and improving biodiversity.

Detainment bunds, small, grassed mounds (1 to 2 metres high) that intercept and collect overland runoff during storms, are one of these tools. The bunds store water for three days. This ensures pasture growth is not reduced but allows sediment and phosphorus to settle out from runoff.

Field-trialling in the Bay of Plenty suggests these bunds can reduce phosphorus and sediment losses by more than half, with a single bund retaining three tonnes of sediment collected during just one storm. DairyNZ scientists are working on refining that estimate, optimising designs and modelling where best to place bunds.

By sharing world-leading and evidence-based research and guidance with our farmers, we hope they'll be able to achieve and exceed water quality goals and regional council compliance requirements with the least impact on farm businesses.

This will not only support environmental sustainability, it will help make dairy more competitive and resilient.

David Burger is environment manager for Dairy NZ