Analysis of decades of research has revealed that good farming practices play a critical role in reducing nutrient losses to improve freshwater outcomes.
Researchers from DairyNZ, the Bioeconomy Science Institute (formerly AgResearch), and Lincoln University explored two decades of data from multiple sources toassess how good farming practices affect nutrient losses.
The study shows a clear link between the widespread use of good farming practices and lower contaminant losses from land to water on New Zealand dairy farms.
DairyNZ senior scientist Dr Katrina Macintosh said farmers should be confident that the actions they took on their farm were having an impact, without negatively affecting productivity.
She said that dairy farmers had applied a range of good farming practices over the past 20 years, including better fertiliser use, effluent management, reduced soil cultivation and improved irrigation scheduling.
Macintosh said that, until recently, few studies had assessed its impact, and when improvements in water quality might be detected.
“In recent years, we’ve been working with milk processors using the data they are collecting from their suppliers via their farm environmental plans to better understand environmental improvements.
Waiorongomai farm planting. Photo / DairyNZ
“Working with Fonterra and Open Country Dairy, plus capturing information from DairyBase, we were able to analyse multiple anonymous datasets to determine the level of good farming practice implementation around the country and what that means for reducing nutrient losses and improving water quality.”
One of the studies assessed five dairy-dominated catchments ranging from 598 to 2480 hectares between 2001 and 2020, a period during which extension programmes began to be rolled out and water quality and farm practices were regularly monitored.
The research found that good farming practices reduced phosphorus, E. coli and sediment concentrations.
Another study assessed the uptake of good management practices over 10 years, between 2013 and 2022 and the influence they had on nitrogen (N) and phosphorus (P) losses to water from dairy-farmed land.
The study found that N management, and improved irrigation and cultivation practices contributed to lower N loss trends. It also found that P fertiliser and effluent storage methods were the most influential parameters for reducing P loss.
Notably, the analysis found that while the adoption of good farming practices decreased N and P losses on-farm, it did not negatively affect milk solid production.
“Good farming practices are generally accessible and cost-effective for farmers to implement on-farm to deliver improved water quality outcomes,” Macintosh said.
“Freshwater management is a long-term game, and it’s great to be able to show farmers the impact of their efforts on-farm over the past 20 years or so.”
DairyNZ said the research built a strong evidence base showing how farming practices on New Zealand dairy farms have changed over time in pastoral catchments to deliver environmental outcomes.
More information
- Download the DairyNZ good farming practices guide for environmental management in dairy farm systems here.
- Read “Assessment of good farming practice implementation by dairy farms in New Zealand: nutrient loss reductions and timeframes for detecting improvement” here.
- Read “A 10-year evaluation of management practices and nutrient losses from dairy farms in New Zealand – Trends and drivers" here.
- Read “Linking the uptake of best management practices on dairy farms to catchment water quality improvement over a 20-year period” here.
