Sustainable Food Trust response to ‘The greenhouse gas impacts of converting food production in England and Wales to organic methods’, a study by Laurence Smith and colleagues published in Nature Communications on 22 October, 2019.


Smith and colleagues’ main conclusion is that converting all farmland in England and Wales to organic production would reduce domestic greenhouse gas emissions from agriculture. However, due to the greatly reduced number of intensive pigs and poultry envisaged under their 100% organic production scenario, lower wheat yields, a considerable fall in oilseed rape production and a significant, postulated, decline in the number of dairy cows, this would lead to significant increases in imported pork, poultry meat, wheat, rape oil and milk, produced from land converted for cultivation. As a result of the soil carbon released from land conversion overseas, the authors estimate that overall greenhouse gas emissions would actually increase considerably.

The Sustainable Food Trust (SFT) works to move the whole food system in the direction of greater environmental sustainability and the adoption of healthier diets, based on the productive capacity of individual countries and regions. Many of the approaches we promote, such as the use of legumes to provide nitrogen fertility in order to reduce the use of synthetic nitrogen fertiliser, are similar to those used by organic farmers. We recognise that the authors acknowledge some of the benefits associated with organic production. However, we see two serious flaws in the study design which create an unrealistic scenario, and this in turn presents organic farming methods in a false and negative light in relation to global warming:

  1. The report’s authors assume a ‘business as usual’ approach as far as conventional (i.e. non-organic) farming is concerned. Yet a huge body of research points to the fact that most current agricultural systems are unsustainable in terms of soil degradation, biodiversity loss, water use, high nitrogen use and more. As a result, it is widely recognised that transformative change is needed to keep inside planetary boundaries for a range of issues, not just global warming. As a result, comparing organic production, which seeks to address as many of these issues as possible, with current agricultural practice, is neither helpful to the development of organic farming, nor useful in helping to point the way to a more sustainable future. Conventional agriculture is already changing and will inevitably change much further.
  2. The study also fails to take into account the ways in which conventional agriculture has changed recently. These include bans on certain pesticides, in particular neonicotinoids, which are already reducing the area of some crops, especially oilseed rape, and a ban on the use of the fungicide chlorothalonil which is also predicted to reduce crop yields due to increased levels of some foliar diseases. There is also no recognition of the problems currently faced by many conventional farmers in terms of increasingly unresponsive soils, increased drought intolerance and growing levels of herbicide resistance amongst some major arable weeds. Problems of this sort are already forcing some growers to adopt less exploitative rotations, not dissimilar to those used by organic farmers. At the same time, a dramatic change to the way in which farmers are supported by the public purse is envisaged under Agriculture Bill and if this comes into law in broadly its current form, the shape of conventional agriculture in England and Wales will change considerably.


Flaws in the business as usual conventional model


  1. The study examines the potential changes in productivity and GHG emissions which could occur if all farmland in England and Wales were to be managed organically. While it is valid to consider the potential limitations of such a transition, the authors fail to recognise that UK agriculture in its current form is unsustainable, is already changing and will inevitably change further. If a transition is not made to more sustainable methods of farming then major problems such as soil degradation on arable land (already a significant problem on many cropland soils) and the decline in wild populations of pollinating insects, will inevitably worsen with serious consequences for agricultural productivity and biodiversity. Should this be allowed to happen, it is not difficult to envisage a future time when productivity on organically farmed land is higher than on conventionally managed land. At the same time, if food producers are not weaned off their over-reliance on synthetic sources of nitrogen fertility, then the huge environmental, atmospheric and human health issues associated with nitrous oxide emissions and nitrate runoff will never be addressed. Similarly, there are growing concerns about the environmental impacts of a significant number of additional pesticides currently seen by growers as essential in maintaining their current high productivity, and it is likely that some of these products will be subject to additional restrictions or bans in the future. Furthermore, an increasingly unstable climate with greater extremes of weather will require a more resilient farming system, the basis of which will be healthy soils with higher levels of organic matter and biological life, that can better deal with periods of drought and flood and maintain yields with lower levels of chemical inputs. It is increasingly recognised that soil health must be improved. While this can be done to a limited extent within a conventional approach, such as the use of cover crops and green manures, the highly exploitative nature of most arable rotations is effectively mining soil fertility and only the re-integration of grass into arable crop rotations and the recycling of composted animal manures has the potential to rebuild soil carbon and therefore soil organic matter significantly. This is a cornerstone of the organic approach and it seems inevitable that conventional agriculture will have to move in this direction if the long-term productivity of soils is to be maintained. Failure to acknowledge this in the study makes it appear that there will be a bigger gap than is likely to be the case between conventional and organic agriculture in the future. It is important to add that a total shift to organic production could not possibly take place immediately – for a start, there are nothing like enough trained organic farming advisers. It would instead need to be carried out incrementally, so that the necessary education and training resources could be built up appropriately.


The flaw in the assumption on diets


  1. While the authors acknowledge in their 2018 study that changes to national diets in tandem with a transition to organic farming would be hugely beneficial, they fail to make any adjustments for this in their latest study and assume that the diet in England and Wales will remain the same under a shift to organic food production. There would undoubtedly be significant declines in pork, poultry, wheat and oilseed production under a fully organic system, which would require an increase in imports if the current high demand for these products was maintained, as is assumed in this study. There are a number of major issues with this approach. First, the authors assume that it would be possible to import sufficient additional quantities of pork from other EU countries. It is not clear this would be the case. The Netherlands, for example, one of our main sources of imported pork, is being required to reduce the intensity of its livestock production due to difficulties in applying such high quantities of animal manure to limited areas of farmland, and the over-enrichment of the environment with nitrogen and phosphates which has resulted. This could lead to decreased overall availability which would increase prices, and this in turn would help to reduce demand, even if consumers were not consciously reducing their consumption of grain-fed meat. In addition, there is a widespread acknowledgement that a significant shift in the dietary patterns of developed countries like the UK, especially in relation to the consumption of intensively-produced meat grown on grain and soya, is urgently needed. This is exactly what, as the authors recognise, organic farming would deliver. Had the necessary transition to a diet with a lower overall intake of calories, a higher intake of vegetables and legumes and a much-reduced share of animal proteins coming from grain-fed livestock been incorporated into their predictions (all transitions suited to organic agriculture), it is likely that their estimate for imports would be greatly reduced, perhaps to even lower levels than at present. The ‘Ten Years For Agroecology’ report produced by French think-tank IDDRI investigated the potential for a wholescale shift to agroecological production methods across Europe, and found that, despite a very similar decline in total food production to Smith et al’s forecast, European food security was maintained and net GHG emissions reduced by 40%, in large part thanks to the incorporation of dietary transitions in their analysis. Significant reductions in the consumption of grain-fed pork, poultry and oilseeds were particularly important in achieving this, alongside a shift to extensively-reared grass-fed ruminant production and an increase in the quantities of vegetables and pulses consumed.


  1. If the significant reduction in intensive pig and poultry production was not replaced by additional imports, there would be a substantial reduction in the need for feed grain and soya protein. Both these would result in greenhouse gas emissions reductions. This would particularly be the case in relation to soya, much of which comes from cleared rainforest land in South America. In the UK, we imported 3.1 million tonnes of soya products in 2016, 1.1 million tonnes of which was fed to farm animals, with approximately 80% of this fed to pigs and poultry. With the increased production of beans and peas envisaged in the organic scenario, the UK could be largely self-sufficient in protein for livestock feed. This could largely eliminate soya meal imports for livestock feed, with potentially huge carbon dioxide and methane emissions savings in terms of rainforest not destroyed in future. In addition to the forest not burned, soil carbon losses would also be avoided on a substantial area of land. Tropical soils can lose up to 50% of their carbon in as little as five years after conversion to agriculture. It is unclear to what extent soya imports are reduced in this study’s analysis, though it appears that an allowance for soya in concentrate feed is still made for monogastric production in particular.


  1. It is true that milk production per organic cow is slightly lower than from conventional cows. This is partly due to greater use of smaller and less productive breeds which are better suited to organic systems and partly due to lower use of concentrate feed. The roughly 20% reduction in dairy cow numbers predicted in this study is driven by the decline in availability of concentrate feeds, which UK dairy production is fairly reliant upon. However, organic cows produce a higher proportion of their milk from grass and the increased use of grass and clover leys under organic production in areas currently dominated by continuous cultivation, could actually be used to support a higher, rather than a lower number of dairy cows, compensating at least partially for any shortfall in yields. Unfortunately, the failure to allow for land use change in this study (see point 6) means that the model did not properly allow for the introduction of dairy cattle into areas currently dominated by arable cropping. If the lost productivity envisaged in the study was made up from increased imports of milk and dairy products from other European countries, the global greenhouse gas emissions would almost certainly be higher than if the milk was produced in the UK. This is because, with the possible exception of Ireland, there is a higher use of grain and soya in dairy cows on the continent, because they do not have the same high level of productivity in their grasslands. As we have previously shown, for every kilo of soya meal fed to dairy cows in the UK, approximately 60 litres of milk are produced. In contrast, throughout the EU as a whole, only 30 litres of milk are produced per kilo of soya meal fed.

Other shortcomings of the study


  1. Major reductions in pork, chicken, wheat and oilseed production could be compensated for by an increase in other products. Although the authors predict an increase in the production of oats, rye, potatoes, and most other vegetables, along with beef and lamb in a wholly organic farming system, the estimated increases are not enough to match the deficit left by the decline in other foods. However, in their analysis, the authors limit the increase in production of any one foodstuff to a maximum of 50% compared to current levels, due to concerns about the limitations of consumer demand. This means that increases in oat, potato and grain legume production are capped in this study, but these outputs would have risen by more had the model allowed it. This suggests there may be potential for greater production of certain commodities than this study indicates under an organic system, and particularly so if demand for these products was driven by a dietary shift or increased exports.


  1. On top of this 50% cap on increased production, the study includes further inflexibility through the decision to ‘fix’ the type of land-use occurring in each area at present, meaning that there was no potential in the model to move away from the current form of production (for instance, areas which currently specialise in cereal production could only remain under specialist cereal production after conversion to organic). The difficulties involved in changing existing farm infrastructure and the constraints of local environmental conditions (e.g. soil type and climate) could cause constraints in some instances, but the study does not consider the significant potential for greater shifts in food production across England and Wales. For example, the integration of crops into some areas in the west of the country that are currently dominated by livestock-only farms could increase the supply of vegetables beyond this study’s estimate, while maintaining adequate meat supplies. More than forty years ago, when agriculture was less intensive, double the quantity of vegetables was grown in Wales. A shift towards dairy-beef systems of cattle production (where herds are run for both meat and dairy production) could also increase the milk supply and reduce GHG emissions per unit of animal protein and dietary fat, but this was not an outcome considered in this study. In their previous paper from 2018 the authors do acknowledge some of these limitations in their recent study does appear to include some re-integration of grazing livestock into crop-dominated areas, but the extent to which the model allows, this appears to have been limited in a way which undermines the full potential of a major transition to organic food production.


  1. The predicted decline in food production could also be lessened through improvements in organic farming techniques. Currently, yields are on average about 20% lower than in conventional systems (though this varies greatly depending on the commodity). In a situation where the UK was entirely farmed by organic methods, all agricultural research funding could be used to help improve organic farming productivity. For well over 70 years, the massive amount of research and development money ploughed into increasing productivity in conventional agriculture (often at the expense of other characteristics such as food quality and environmental well-being) is the single most significant reason agriculture has become so much more productive. Although there may be less potential to increase yields to the same extent on organic farms, there is currently a wide disparity in productivity between the most productive and the least productive organic farms, suggesting significant potential for improvement with better training and support, quite apart from the potential from research into crop varieties better-suited to organic farming, better rotations and increased legume nitrogen availability. This is acknowledged by the authors in their 2018 study, but not in the most recent one.


  1. In relation to the study’s estimation of soil carbon sequestration potential, this is a notoriously difficult area to model, partly because of a lack of evidence and contrasting findings. The sequestration rates provided in this analysis are reasonable and achievable, but on the low side, compared with those reported in some studies. Most high-yielding plants grown in conventional production are relatively shallow-rooting and fed by fertiliser applied on top of the ground or incorporated into the top few inches of soil. Soil carbon is generally only measured in the top few inches of soil, but this may not be an accurate way in which to estimate soil carbon sequestration levels in organic soils. Organic crops get their fertility from decayed organic matter in the soil. This is one reason why organic farmers generally use deeper-rooting grasses, legumes, herbs and even cereals, than conventional farmers. As a result, the roots, which can go down several metres, will be laying down carbon at much greater depths than in conventional situations where this is not being measured. Another shortcoming is that the study does not include the very significant additional carbon sequestration benefits that would be generated from increased hedgerow, field-margin tree and agroforestry cover. Increases in grazing livestock will require additional stock-proof field boundaries and for shelter and environmental reasons this would provide an incentive to plant more hedges. In addition, there is no mention of the potential increases in soil carbon from the use of green manures and cover crops which, like hedgerows and agroforestry, also bring many other major environmental and agricultural benefits. Finally, there may be the potential to improve soil carbon levels in improved pastures, which are assumed here and elsewhere to hold no additional carbon sequestration potential. This is because of recent research which found that an optimum soil pore structure, provided by high plant species diversity, results in significantly greater levels of carbon sequestration than in species-poor grasslands. More evidence is needed in this area, but the discovery of this hitherto unknown mechanism could mean that improving plant species diversity in the UK’s extensive pastures, as is generally the case in organic leys and permanent pastures, can provide greater sequestration potential than previously thought possible.


  1. In comparing the greenhouse gas emissions of organic and conventional agriculture, the study makes no allowance for the carbon that has been lost from conventionally managed soils over previous decades. It is known that most cropland in the UK has lost at least 40% of its carbon. While it might not be appropriate to factor this into a comparison going forward, the extremely long atmospheric lifespan of carbon dioxide means that each tonne of soil carbon lost to the atmosphere in the past will have an annual undiminished global warming impact for at least the next 1000 years, unless some low energy effective form of carbon capture is successfully developed.


  1. The authors postulate a significant reduction in the area of land growing oil seed rape organically, and factor in the emissions associated with the production of an equivalent quantity of oilseeds in other countries, to be then imported into England and Wales. However, according to Defra, 132,000 hectares of land are currently producing biofuels, 53% of which is OSR. This equates to 70,000 ha. In addition, largely due to the problem of controlling pests because of the ban on neonicotinoid insecticides, the Association of Independent Crop Consultants is forecasting an 18% decline in the area of OSR in 2020. This equates to a further reduction of 90,000 hectares. Therefore, OSR productivity from conventional agriculture could be 160,000 hectares (32%) – or almost half a million tonnes lower in 2020 than in 2019. The difference could well be higher than this because the survey of rape growers on which these projections are based found that in the South-East of the country, where rape yields in the past have been the higher than average, OSR production is expected to decline by 25%. These declines reflect the unsustainable nature of most OSR production, highlighting the need to move away from our current high reliance upon rapeseed oil and re-consider greater dietary use of animal fats.


  1. In terms of comparing productivity in organic and conventional systems, greater consideration is also needed in relation to differences in the quality of the end products. The UK has a huge food waste problem. Part of this arises at a production level and part of it relates to food wasted by consumers. Organic food generally costs more, due to the lower yields and higher levels of labour needed to produce some commodities. However, there are a number of studies showing that organic food is generally higher in a range of micronutrients needed for health. Many people also believe that organic food generally tastes better than conventional food. An example would be broccoli and other greens. These are very valuable for health, but often rejected by children as tasting bitter when produced conventionally. In contrast, there is compelling personal testimony to indicate that these foods are not rejected in the same way when the crops are produced organically. As such, due to the combination of higher prices, higher levels of micronutrients and better taste, we believe it is reasonable to assume that levels of waste generated by consumers eating organic food would be very much lower than at present, because they would value the food more. However, reducing food waste is required irrespective of the production system, and achieving this would dramatically reduce the need for imports, giving England and Wales much more leeway to adopt organic farming practices whilst maintaining food security.


  1. A high proportion of conventionally grown crops are irrigated. There are no national statistics, but due to the high organic matter levels in organically managed soils, the need for irrigation will be lower because organic matter retains moisture far more effectively that soil itself. This could become highly significant in future. Parts of Eastern and South-Eastern England are already short of water and it is predicted that there will be increased use of water restrictions in future, which is likely to reduce conventional yields more than those on organically farmed land.


  1. This study focuses purely on food productivity and GHG emissions, two enormously important issues. However, it is imperative that we consider the full range of environmental and social impacts of food production and consumption. Protecting and improving the UK’s biodiversity, air and water quality and soil health is critically important, and the main way to achieve this is through better integrated forms of agriculture. There is the danger that by simply focussing on productivity and GHGs, the likes of biodiversity may suffer. It is crucial, therefore, that we achieve a suitable balance, even if this is difficult and requires some compromise on GHG emissions.

Richard Young and Robert Barbour, Sustainable Food Trust  

This is an initial response from the SFT, further references and comments may be added.

October 2019

Photograph: Heather Cowper

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