Manure happens

Scientists speaking at the Royal Society, the UK’s national academy of science, today (28 February) say it will be difficult but nevertheless important to significantly reduce emissions of the greenhouse gas nitrous oxide (N2O) while also improving the diets of a growing global human population.  The experts are taking part in a discussion meeting on reducing greenhouse gas emissions from agriculture.

Large quantities of N2O are currently emitted by the use of synthetic nitrogen fertilizers and from livestock manure in farming. The agricultural sector produces 70-80% of all anthropogenic N2O emissions. Following CO2, and methane, N2O is the third most important anthropogenic greenhouse gas and it is also a reactant in the destruction of the ozone layer.

Dr Eric Davidson from the Woods Hole Research Centre in the USA will be discussing the realities of feeding billions of humans, most of whom eat meat, while trying to stabilise atmospheric greenhouse gases. He says that for agriculture to be sustainable in the long term, we must develop technologies and management options that simultaneously allow increases in agricultural productivity to meet a growing demand for nutritious human diets, while reducing the emissions of greenhouse gases.

Dr Davidson says:

“Reducing per-capita meat consumption in the developed world will have only a modest effect on atmospheric N2O concentrations because the developing world is already consuming more meat as their populations grow and improve their diets. Without major technological and management improvements that increase the efficiency of nitrogen use by crops and decrease losses from manure management, the rate of N2O will not begin to decrease significantly.

The good news is that many off-the-shelf technologies and existing management approaches could take us a long way towards this goal.  The bad news is that the political will to incentivize farmers and other stakeholders to adopt practices that would mitigate N2O emissions is largely lacking.”

In his talk, Dr Davidson will discuss four scenarios of future greenhouse gas concentration trends that the Intergovernmental Panel on Climate Change (IPCC) fifth assessment report will be considering.

In addition to Dr Davidson’s talk, experts taking part in the two-day discussion meeting will discuss carbon negative grazing systems; bioenergy and land use; and socio-legal perspectives on UK agriculture and climate change.