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Soil Association rebuts greenhouse gas claims in organic farming report

23rd Oct 2019 - 10:57
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Soil Association greenhouse gas emissions study Cranfield
Abstract
A Cranfield University report that suggests 100% organic farming could increase greenhouse gas emissions has been challenged by the Soil Association, the charity that runs an organic certification scheme.

Rob Percival, head of food policy at the Soil Association said: “The assumptions behind the study’s conclusion that there will be a net increase in greenhouse gas emissions under organic are fundamentally flawed.

“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."

The report says that 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.

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.

Percival added: “We’ve known for years that dietary change – a move towards ‘more and better’ plants and ‘less and better’ meat – will benefit the public’s health and free up land, making an organic scenario entirely feasible.

“In particular, we need to stop feeding so many crops to animals – 58% of cereals and 68% of oilseed crops currently – this means eating less intensively produced grain-fed poultry and pork.

“The recent study from French thinktank IDDRI suggests that Europe could adopt 100% agroecological farming, akin to organic, and still feed a growing population a healthy diet, while protecting biodiversity and helping to meet net-zero targets for climate change.”

The Cranfield study, published in Nature Communications, was principally conducted by Dr Laurence Smith while he was at Cranfield University, with Professor Guy Kirk and Dr Adrian Williams of Cranfield University and Philip Jones of Reading University.

Dr Smith said: “Although resource use can be improved under organic management, there is a need to consider the potential effect on land-use.

“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.”

Dr Williams added: “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.”

If imports were used to make up the shortfall, and food demands stayed the same, the team estimates the overseas land area needed to produce food for England and Wales would increase by a factor of five.

This land would likely be poorer quality and not as productive.

The researchers acknowledge that carbon dioxide capture is higher under organic farming, but said this benefit would only last for the first 10 years of a wholesale switch to organic.

The research concluded that net GHG emissions under a 100% organic farming production method could increase by 21% over conventional farming baselines.

Dr Williams concluded: “The assumption about diets is crucial: today’s organic consumers are a self-selecting group and not typical of the nation.

“Whether a different national diet could be provided by the same land area under all organic production is a different study. This was aimed at understanding limits to production.”

Dr Smith is now at the Royal Agricultural University.

 

Written by
David Foad