Lowering Daisy's emissions: Battle against agricultural climate offenders

Agriculture accounts for approximately nine per cent of Norway's total emissions of greenhouse gases. Now, researchers are acquiring actual gas measurements and new knowledge about what causes the emissions -- with the aim of mitigating Norwegian agriculture's impact on the climate and environment.

In particular, it is emissions of the greenhouse gases methane (CH₄, from cattle) and nitrous oxide (N₂O, from the soil and fertilisers) that make agriculture such a major climate culprit. N₂O has nearly 300 times the climate-warming effect of CO₂ while methane has 21 times the effect.

Ruminating on the right feed

Professor Odd Magne Harstad of the Norwegian University of Life Sciences (UMB) has now outfitted cows with advanced monitoring equipment and sent them out to summer pasture. His objective is to quantify the animals' actual gas discharges and to document the possible effect of different feed additives such as fatty acids on their methane emissions.

"With the right feed and other feeding-related measures," says Professor Harstad, "we believe it may be possible to reduce methane emissions by 10 to 15 per cent. Since methane makes up such a large proportion of greenhouse gas emissions, a reduction of this size would be very significant."

Unveiling the secrets of N₂O

In the battle to reduce agricultural emissions scientists at UMB, are also intent on solving the riddles of how and why the greenhouse gas N₂O is formed. This knowledge is critical for softening the environmental and climate footprint of agricultural production in Norway and the rest of the world.

"A year of research effort indicates that geographical conditions and soil type probably play a major role in nitrous oxide emissions," says Peter Dörsch, Senior Scientist at UMB. With funding from the Food Programme, he is measuring emissions from the production of grain and grass in various areas of Norway.

"We're working on understanding why, for instance, low pH values in soil are so important in the formation of nitrous oxide," says Professor Åsa Frostegård, also of UMB. "We're currently studying how different fertiliser components affect agricultural N₂O emissions. If we don't understand the underlying mechanisms, we could end up prescribing medicine for Mother Nature without knowing why it works or what side effects may be involved," she adds.

Sound agronomy

The UMB researchers are confident this new knowledge about nitrous oxide will attract international attention, but they are less certain about finding a definitive solution to the problems of greenhouse gases. What they do know for sure is that each individual farmer can make a difference by employing proper growing methods.

"At present, we do not know how or the degree to which we will be able to reduce N₂O emissions," says UMB Professor Lars Bakken, "but we know that good agronomic practice is an effective tool. And if a solution exists for lowering emissions while at the same time maintaining the efficiency of food production, we're going to find it."

The greenhouse gas nitrous oxide (N₂O) is formed from nitrates through denitrification, a natural process in the nitrogen cycle by which nitrogen bound in the soil is returned to the atmosphere in its gaseous state. When farmers over-enrich their soil (fertilise it with more nitrogen nutrients than the plants require), excessive nitrous oxide is produced. But depending on factors such as the soil's temperature, pH value, and oxygen and moisture content, much nitrate can be converted to harmless nitrogen gas.