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100% organic conversion - GHG impacts

Category: News
25 October 2019

The greenhouse gas impacts of converting food production in England and Wales to organic methods

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) and supported by the Organic Research Centre, 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 says, “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. This additional land would likely be of sub-optimal quality and therefore not as productive as higher-quality land.

Dr Laurence Smith says, “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.”

Storing carbon in the soil

Rates of carbon sequestration – where atmospheric carbon dioxide is captured by plants and stored in the soil – are higher under organic farming because of greater use of manures and longer crop rotations. However, this is limited to the first decade or two following conversion to organic farming, as the soil will eventually reach a steady-state when carbon sequestration rates fall to zero. Overall in the 100% organic farming modelling, it was found that sequestration only offsets a small part of the higher emissions from overseas land use.

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 -under the assumption that only half the extra overseas land was converted from grassland - going up to 170% if the Carbon Opportunity Cost [2] is added in.

Guy Kirk, Professor of Soil Systems at Cranfield University, says: “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.”

Dr Adrian Williams concludes, “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. The study was based on rigorous modelling that had its foundations in establishing the biophysical limits of crop production without manufactured nitrogen.”

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 by academics from Cranfield University, the Royal Agricultural University and the University of Reading.

In the press

On the radio

Reaction to the paper

The Organic Center in the US responded in this blog Myopic Misinformation about Organic and Climate Change

Prof Dave Reay, Chair in Carbon Management at the University of Edinburgh, said Source: Science Media Centre: “These findings are not surprising. By definition, organic food production doesn’t use the artificial fertilisers and pesticides that can super-charge yields in conventional systems. Lower yields nationally therefore mean more imports, and so off-shoring of land use change and emissions. This is important – the climate doesn’t care where greenhouse gases are emitted, it’s how much that matters – but land use is not just about greenhouse gas emissions.

“We face a fiendishly difficult balancing act between cutting emissions, producing enough food, and protecting biodiversity and the myriad other gifts the land provides. Organic food production methods have an important role in achieving this balance – you can use all the precision farming methods and fancy fertilisers you like, but if the pollinators are all killed by pesticides you’re still in a heap of trouble. Yes, food production in some areas must become much more efficient so as to free up land elsewhere for carbon sequestration. Yes, our diets must change and cuts in food-related emissions at home must not come at the expense of greater emissions .

Rob Percival, head of food policy at the Soil Association said; “The study recognises the greater potential for soil carbon sequestration under organic, plus benefits for local biodiversity. 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. 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. In the UK, over a hundred organisations and leading figures in food, farming, environment and health have backed the recommendation of the RSA’s Food, Farming and Countryside Commission that the UK commit to a 10-year transition to agroecology. This doesn’t mean the UK going 100% certified organic, but there is now widespread recognition that the inter-related crises of climate, nature and health demand a joined-up solution. An agroecological UK, with organic farming at its heart, is that solution.“

Roger Kerr of OF&G's response, in a letter to the Farmers Weekly said: "OF&G (Organic Farmers & Growers) is disappointed with the research conclusions that state moving to organic would increase greenhouse gas (GHG) emissions by off-shoring our food production due to lower yields.

"The research appears to fail in several critical areas. Firstly, it fails to recognise the impact on GHG emissions from the manufacture of external agricultural inputs. A recent study by Sheffield University showed ammonium nitrate fertiliser alone used in wheat cultivation contributes to almost half (43%) of the GHG emissions associated with industrial bread production – dwarfing all other processes in the entire supply chain.

"The percentage reduction in yield in organic systems cited in the research is also arguable, however, research undertaken by FiBL states that while organic may have lower yields, it represents part of a sustainable solution.

"The research also fails to address significant structural issues in our current food system. It’s suggested around 30% of food produced in the UK is wasted and around 40% of the world’s cereal production goes to feeding livestock in intensive systems. 30% of the US cereal crop alone currently goes into biofuel production. It’s a sobering thought that while 820 million people on the planet don’t have enough to eat, 2,100 million are overweight or obese according to the UN. If we reduced waste and focused on feeding people nutritious diets and not feeding cars or livestock, organic production could feed the world. In the face of these statistics to simply dismiss organic on the grounds that it can’t fulfil the needs of a dysfunctional food system seem perverse. It seems, therefore, we need a new approach to defining productivity and efficiency - one which allows the benefits of a joined-up system approach.OF&G recently argued for this in a report proposing a rethink of our definition of productivity and efficiency so that externalities are recognised in a balance sheet approach. Done this way, there’s every reason to believe an organic system is both efficient and productive, with significant benefits of cleaner air and water, and improved biodiversity.

"The research in Nature Communications doesn’t recognise that the general farming approach over the last 50 or 60 years has led to impoverished soils and contributed toward a significant reduction in biodiversity. In the UK, there’s been a 56% decline in farmland birds since 1970 and it’s suggested there’s now only 100 harvests left in our soils. Although the research recognises the benefits an organic system brings to soils and biodiversity, it fails to take a joined-up approach, which has proved to be great fodder for the advocates of ‘business as usual’ - something the IPCC and the UN has agreed is no longer an option."

Keywords: Conversion GHG Greenhouse gases

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