Switching to 100 percent organic farming would push up emissions, says study

23 Oct 2019 --- Completely switching from conventional to organic agricultural practices would result in an overall increase in greenhouse gas (GHG) emissions, according to new research conducted in England and Wales. A recent study published in the journal Nature Communications highlights that while organic farming might require less farm inputs and increased soil carbon sequestration, it might also worsen emissions through greater food production elsewhere to make up for lower organic yields. Compared to conventional methods, overall emissions in organic farming could rise by 21 percent, note the researchers.

“To date there has been no rigorous assessment of this potential at national scales,” the authors of the study note. “[In our research] we assess the consequences for net GHG emissions of a 100 percent shift to organic food production in England and Wales using life-cycle assessment. We predict major shortfalls in production of most agricultural products against a conventional baseline.”

Based on their assessment, the researchers suggest that the agricultural sector would see a drop in emissions of around 20 percent for crops and around 4 percent for livestock. This reduction, however, would be offset by significant drops in food production, by around 40 percent compared to conventional farming.

The authors attribute this decrease in emissions to the lower crop yields and the implementation of nitrogen-fixing legumes in crop rotations, which would reduce the amount of land available for production. As a result, crops such as wheat and barley would see prominent decrease in output. In livestock, sheep and beef cattle raised in an organic setting would increase, while volumes of meat would be reduced, due to lower carcass weights and longer finishing times under organic management.

Direct GHG emissions are reduced with organic farming, but net emissions are greater when increased land use abroad compensates for shortfalls in domestic supply, the researchers note. “Enhanced soil carbon sequestration could offset only a small part of the higher overseas emissions.”

The authors juxtapose their findings with the significant benefits of a fully organic farming future: cleaner air and water, and improved biodiversity. Critics of the study, however, are zooming in on a suggestion that the switch would not result in prominent dietary shifts.

“The assumptions behind the study's conclusion that there will be a net increase in greenhouse gas emissions under organic are fundamentally flawed,” says Rob Percival, Head of Food Policy at the Soil Association.

“The study assumes no change in diet, which is clearly untenable given the global dietary health crisis, and that we would keep diverting most of our cropland to over-production of the wrong things – livestock feed, commodity crops for processed food and biofuels.”

"Whether a different national diet could be provided by the same land area under all organic production is a different study,” responds co-author Dr. Adrian Williams of Cranfield University. "This was aimed at understanding limits to production. The study was based on rigorous modelling that had its foundations in establishing the biophysical limits of crop production without manufactured.”

“The assumption about diets is crucial: today’s organic consumers are a self-selecting group and not typical of the nation,” he concludes.

By Benjamin Ferrer