Productivity key to reducing emissions: study

Improved productivity could reduce on-farm greenhouse gas emissions from sheep by up to 12%, according to the author of a study which calculated the carbon footprint of sheep.

Stewart Ledgard, a principal AgResearch scientist, said a higher lambing percentage and faster lamb growth rates offered the best options for reducing greenhouse gas emissions from sheep, as opposed to reducing fossil fuel use, which was low on sheep farms compared with other intensive agricultural systems.

Dr Ledgard said the 1.9kg of CO2-equivalent produced for each 100g portion of lamb exported to Europe, was "broadly consistent with other international studies of products derived from farmed, ruminant livestock."

His study found 57% of the sheep carbon footprint was generated by the natural process of animals utilising pasture and producing methane during digestion, but it was a figure that has been decreasing.

"Our analyses showed that this component of the carbon footprint has decreased by over 20% during the past 15 years, as farmers have made large gains in efficiency of converting pasture to meat."

Dr Ledgard said in an interview the survey allocated emissions from a typical mixed sheep and beef farm and also took into account wool production.

The study would help meat companies satisfy carbon footprint questions from customers, and provide a starting point for sheep farmers about to face an emissions trading scheme.

A recent report on the dairy industry concluded that total emissions from New Zealand dairy farms were substantially lower than those in Europe, and a Fonterra-commissioned report found the life-cycle carbon footprint of New Zealand ingredient and consumer dairy products was 940g for each litre of milk.

Dr Ledgard was part of a team which compared the energy and greenhouse gas efficiency of New Zealand farming systems with those in Europe.

The team concluded that New Zealand was more efficient, even taking into account shipping products to Europe, which only contributed 10% of the total energy use.

The study warned that intensification of dairy farming risked diminishing New Zealand's comparative advantage.

Dr Ledgard's study showed that most gains from reducing emissions would come from the most complex task, that of changing the natural biology and behaviour of animals.

A solution was at least seven years away, according to Mark Aspin, the manager of the Pastoral Greenhouse Gas Research Consortium.

Mr Aspin said any solution had to reduce methane and/or nitrous oxide in grazing ruminants; have a neutral effect on productivity, or enhance it; and it had to be able to be delivered and administered cost-effectively.

The consortium was looking at reducing methane through animal selection, screening for small molecule inhibitors in the microbes responsible for its production, and a vaccine.

AbacusBio scientist Peter Amer said a positive finding with sheep emissions was the 5% contribution of CO2 from transport, which should negate the food miles argument while also providing an opportunity to promote New Zealand lamb as having low baseline emissions.

Prof Jacqueline Rowarth, the director of Agriculture at Massey University, said New Zealand had set a benchmark and other lamb-producing countries would try to prove their emissions were lower, putting the onus on New Zealand farmers to reduce emissions further.

Meanwhile, a recent report to the American Chemical Society said eating less meat and dairy would do little to mitigate the impact of climate change, because greenhouse gas emissions from livestock in most developed countries made up a small percentage of overall emissions.

Associate Prof Jonathan Hickford, of the faculty of agriculture and life science at Lincoln University, said the Lord Stern report - which advocated eating less meat and dairy to slow global warming - missed the point that vast areas of land were only suited to growing grass.

"Without a grazing animal you could not use this land resource to produce food for the population," he said.