An AgResearch-commissioned sustainability study of the country's farms found that while they remained more efficient than their European Union counterparts, the gap was closing.

AgResearch principal scientist Dr Stewart Ledgard said dairy farms here were ahead of those in the European Union (EU) in terms of on-farm energy use and food miles.

However, their "competitive advantage is diminishing", he said.

"Farmers need to start using knowledge of the main factors influencing greenhouse gas emissions to improve farm practices or plan intensification options and retain their competitive advantage."

Increasing productivity per animal and optimising use of effluent to reduce fertiliser used were two options to decrease emissions, he said.

Farmers are to join the Government's Emissions Trading Scheme (ETS), aimed at driving down New Zealand's greenhouse gas emissions, in 2013.

Source: New Zealand Herald