Co-benefits and trade-offs of water quality mitigation measures on greenhouse gas emissions from New Zealand dairy systems

As part of government climate change policy, New Zealand dairy farmers will be encouraged to reduce their greenhouse gas (GHG) emissions through a proposed pricing mechanism.

With integrated farm plans on the horizon, farmers need information on how mitigations for water quality will impact GHG emissions. Using a typology approach that captured the main production attributes and drivers of nitrogen (N) and phosphorus (P) losses to water we assessed the impact of 12 current N and P contaminant mitigations on GHG co-benefits or trade-offs. Four of the mitigations had a co-benefit effect, with most of these being N mitigation measures.

Trade-offs were detected for two water quality mitigations (stand-off pads and deferring effluent application), resulting in an increase in estimated GHG emissions. The remaining six water quality mitigations tested, either had a minimal impact, or had both a tradeoff and co-benefit. Our data provides pastoral farmers and rural professionals with information to guide initial conversations on options to reduce losses to water and air for developing integrated farm plans.