Research found direct greenhouse gas emissions are reduced with organic farming but increased imports means net emissions are greater
A 100% shift to organic farming in England and Wales would yield up to 40% less food if the nation did not change its diet. Leading to increased imports and a net increase in greenhouse gas emissions, researchers have found.
The study, published in Nature Communications was principally conducted by Dr Laurence Smith, whilst at Cranfield University (now of the Royal Agricultural University), with Professor Guy Kirk and Dr Adrian Williams of Cranfield University and Philip Jones of Reading University.
Organic farming produces less emissions, but produces less food
Although organic farming generally creates lower greenhouse gas (GHG) emissions per commodity, up to 20% lower for crops and 4% for livestock, it also produces less food energy output per hectare. Dr Adrian Williams, Reader in Agri-Environmental Systems at Cranfield University said:
“We predict a drop in total food production of 40% under a fully organic farming regime, compared to conventional farming, if we keep to the same national diet.
“This results from lower crop yields, because yields are restricted by a lower supply of nitrogen, which is mainly from grass-legume leys within crop rotations or manure from cattle on pasture.”
Assessing the need for imports to make up the shortfall, and assuming that food diets and demands stay the same, the academic team estimates that the overseas land area needed to be changed to food production for England and Wales would increase by a factor of five.
Dr Laurence Smith, lecturer in Agroecology at the Royal Agricultural University, said:
“Under a 100% organic scenario in England and Wales, a net-reduction in greenhouse gases would only be achievable if accompanied by a major increase in organic yields or widespread changes to national diets.”
Net emissions are greater
The research concluded that net GHG emissions under a 100% organic farming production method could increase by 21% over conventional farming baselines. This was under the assumption that only half the extra overseas land was converted from grassland – going up to 170% if the Carbon Opportunity Cost is added in.
Guy Kirk, Professor of Soil Systems at Cranfield University, said:
“Although there are undoubted local environmental benefits to organic farming practices, including soil carbon storage, reduced exposure to pesticides and improved biodiversity, we need to set these against the requirement for greater production elsewhere.”
The greenhouse gas impacts of converting food production in England and Wales to organic methods was published in the journal Nature Communications on Tuesday 22 October 2019.