DairyNZ
Analysis of two decades of research shows good farming practices play a critical role in reducing nutrient losses and improving freshwater outcomes.
Researchers from DairyNZ, the Bioeconomy Science Institute, formerly AgResearch, and Lincoln University analysed multiple data sources to assess how the implementation of good farming practices has influenced nutrient losses on New Zealand dairy farms.
The results show a clear link between widespread adoption of these practices and lower contaminant losses from land to water.
DairyNZ senior scientist Dr Katrina Macintosh says farmers can be confident their actions are making a difference without affecting productivity.
“Over the past 20 years dairy farmers have implemented a range of good farming practices, including better fertiliser use, effluent management, reduced soil cultivation and improved irrigation scheduling. Until recently, few studies assessed its impact, and when improvements in water quality might be detected,” she says.
In recent years, researchers have worked with milk processors using data collected through farm environmental plans. By working with Fonterra and Open Country Dairy, alongside DairyBase information, the team analysed multiple anonymous datasets to determine the level of good farming practice implementation nationwide and what it means for nutrient losses.
One study examined five dairy-dominated catchments between 2001 and 2020, when extension programmes were introduced and water quality was regularly monitored. It found reduced phosphorus, E. coli and sediment concentrations.
Another study analysed uptake of good management practices between 2013 and 2022 and their effect on nitrogen and phosphorus losses. It found improved nitrogen management, irrigation and cultivation practices reduced nitrogen losses, while fertiliser and effluent storage methods were key to reducing phosphorus loss.
Importantly, reduced nutrient losses did not negatively affect milk solid production.
“Good farming practices are generally accessible and cost-effective for farmers to implement to deliver improved water quality outcomes,” Katrina says. “Fresh water management is a long-term game, and it’s great to be able to show farmers the impact of their efforts.”
The research strengthens evidence showing changes in dairy farming practices over time are delivering environmental benefits.
