Knowledge for better food systems

Carbon Footprint Organic vs Conventional

Will Nicholson's picture

Hi,

I am trying to find good ranges of data concerning if organic food has a higher or lower carbon footprint than non-organic food.  I have no ideological axe to grind about this, but the research I have been involved in, and work with research groups, tends to show that organic and non-organic carbon footprints (for different products) have similar ranges.  In other words, there is not enough research to say confidently that, for example an organic apple has a lower (or higher) carbon footprint than a non-organic apple (and etc etc for carrots, beef, chicken, potatoes).  This seems to be due to the trade-off between energy inputs and yield levels.

Now then... I have repeated discussions with people from the pro-organic movement who refuse to acknowledge that this could be the case - even when I show them metastudies that would back up this position.

The reason this matters (to me) is that I help food businesses to develop more sustainable food policies, and when it comes to reducing their carbon footprint I feel obliged to suggest that they should not assume organic to be lower carbon footprint than non-organic, but they should look at the meat/veg balance (especially when organic food is low supply in the area I work).  But this is causing a lot of friction on a business level with people who are definitely pro organic food.  It is almost as if they cannot take criticism...

Am I missing something, or is my position reasonably valid?  (I am happy to be wrong so far, like I said, I have no ideological axe to grind)

Thanks

Will.

John Kazer's picture
Submitted by John Kazer (not verified) on

Hi Will,

You mirror my personal experience exactly.  Passion is a good thing but we should temper it with suitable knowledge and debate when available!

My practical experience is that most companies shy away from publishing results in this area and academics often struggle to gain access to enough real production data.  Companies rarely have a core interest in diving into this debate but where I have seen data it is as you suggest, mixed.

Agriculture as an industry is unique in the range of efficiencies found within producers of the same product (for what ever reason this may be).  It is normally very hard to distinguish between this variability and any differences in production method.

Some production techniques may tend to be more efficient regarding GHG emissions but often worse on other metrics (e.g. land utilisation, water use, welfare, profitability, NP pollution etc.).

It *should* be easier to do the analysis for the more "standardised" products, such as horticulture, arable, chickens and pigs but I don't know of any studies of any significant scale to date that use real organic farm data.

John

Peter Melchett's picture
Submitted by Peter Melchett (not verified) on

Dear Will,

I will try to answer your question (does organic food have lower ghg emissions than non-organic?), and some of the points made in subsequent comments, on behalf of the Soil Association (a UK organic organisation).  To start, I think it is worth noting two significant gaps in information about the carbon footprint of organic and non-organic food. First, although there have been quite a few Life Cycle Assessments, there is a paucity of good original data to put in to LCA models. On investigation, we have found that many LCAs simply take data from previous work.

Second - and this is a gap that the organic movement is most concerned about - currently LCAs do not take in to account losses or additions to soil carbon caused by different farming systems. Indeed, soil carbon losses are often not included in national ghg inventories. The UK for example, includes the (large) losses from lowland peat in areas like the Fens, but not soil carbon losses (or gains) from other soils. This is partly because there is little data on such carbon lossesand gains, and because they need to be measured over fairly long periods of time to get a good picture of what is really happening. In addition, at least in the UK, there is some academic dispute about whether soils (apart from exposed peat soils) are still losing carbon or not.

Overall, we do not agree with your conclusion so far, that ‘the complexity overshadows the dichotomous conventional vs organic debate’, and do not think that ‘would be a reasonable position to take’, based on the available evidence, for reasons I set out below.
 Even with the qualifications as to the quality and scope of the data used, there is no argument in the literature that organic farming in general produces less greenhouse gas emissions per hectare of production (and that is without accounting for soil Carbon losses or gains).  Generally, organic production also produces less ghgs per kilogram of production, although for some products the ghg emissions will be similar for organic and non-organic.
The clearest evidence is with energy use, as it is easiest to measure, while of course only representing a small proportion of the ghgs from farming. 

A Defra study concluded: ‘Organically grown crops require around 50% of the energy input per unit area than do conventional crops, largely because of lower, or zero, fertiliser and pesticide energy inputs. However, the generally lower yields of organic crop and vegetable systems reduce the advantage to organic when energy input is calculated on a unit output basis. In stockless arable crop rotations, the inclusion of fertility building crops and winter cover crops, that have energy inputs but no direct outputs, can result in lower whole-rotation energy efficiency from organic methods. In livestock systems, where the fall in output may be less than in arable, and there are no dedicated fertility building crops, overall energy efficiency is greater in organic than in comparable conventional systems.’  While there are some stockless organic farms in the UK, they are unusual (see below).

Another study1 concluded: ‘The energy use was generally lower in the organic than in the conventional system, but yields were also lower. Consequently, conventional crop production had the highest energy production, whereas organic crop production had the highest energy efficiency... Energy use for both conventional cattle and pig production was found to be higher than that for organic production’.

The early work at Cranfield University by Williams et al2 showed that for most arable crops, organic produces less ghg emissions per kilogram of production than non-organic. However, that early work suggested that for products like poultry and eggs, ghg emissions for organic were significantly higher than for non-organic (the same was assumed to be true for pigs). More recent Defra-supported research projects3 showed that greenhouse gas emissions for organic pigs or poultry are equivalent to non-organic free-range pig and poultry systems, per kg of production, although both free-range and organic have higher ghg emissions than non-organic intensive, indoor systems. These calculations did include the relevant IPCC factors for Land Use Change (LUC) attributable to soya production in Latin America – the source of most of the protein fed to non-organic UK pigs and poultry (and indeed dairy cows), but many earlier LCAs did not. Organic soya imported in to the UK does not usually come from Latin America, but will currently come with a high ghg footprint from transport. 

However, as organic crops cannot be grown, under organic standards, on recently converted land, there will not be an LUC factor to apply.  Organic standards encourage animal feed produced on the farm, and home grown organic peas and beans are increasingly looked at as alternatives to soya.

Much more work on climate change and agriculture has been done in countries like Germany, Austria and Switzerland, than is the case in the UK.  For example, in-depth research in Germany found that organic management on a farm resulted in lower greenhouse gas emissions than conventional management at the same site. This was largely due to carbon sequestration in soils (which were being depleted under conventional management) and due to lower N20 emissions due to the absence of artificial fertiliser.4

Indeed, recent meta-analyses that have reviewed studies from all over the world show that such findings are common. One meta-analysis found that organic farms have 3.5 metric tonnes more carbon in their soils than conventional farms.5 Another found that organic farm soils emit less N20 per hectare and take-up slightly more methane.6. Whilst this study found higher emissions of N20 when the results were scaled to yield, this is likely to be lower if the N20 emissions from the manufacture and use of manufactured fertiliser are accounted for.  N20 emissions account for more than half the ghg emissions from farming. 

While organic farming also relies on nitrogen for fertility, this is fixed by legumes (typically clover or lucerne/alfalfa). While there will be N2O emissions when the nitrogen fixing part of the rotation comes to an end (typically after three to four years, but much shorter in tropical countries), these come nowhere near the N2O emissions from the regular applications of manufactured N in non-organic systems, which operate at much higher levels of N inputs.  Furthermore, while high levels of N, crucially along with high inputs of mined Phosphate, lead to higher yields for cereal crops and field vegetables like carrots or potatoes, this is not so much the case for N-fixing crops like peas or beans,7 nor generally for fruits.8

Of course, if output (yields) were measured in tonnes of edible food per tonne of non-renewable inputs per hectare, instead of simply tonnes of output per hectare (regardless of the financial, environmental or social costs of the input required to achieve a particular yield), that would favour low input farming systems like organic.9

This is a framing issue, determined by societal values and politics, not science. In the current tonnes per hectare model, for example, the cost in  millions of pounds of extracting pesticides from drinking water are ignored14 years ago the cost of pesticide contamination in drinking water was calculated to be £120 million a year.10

More recently, one case study catchment found pesticide extraction cost £96,000 a year for water which supplied 160,000 people,11 as are the social and environmental costs of the 50% (and for some previously common species 90% or more) loses of farmland birds over the last 40 years Defra farmland bird index – index for farmland bird populations has declined by more than 50% since the 1970s.12

The second most significant ghg emissions from farming come from methane – around 44% of farming’s emissions in the UK,13 and higher than that globally.  Here, grass-fed livestock, particularly extensive beef and sheep, will have a significantly lower carbon footprint, if the carbon sequestered in permanent and semi-permanent, natural and semi-natural grazing land is taken in to account.14 In non-organic systems, the higher ghg emissions associated with cereal and protein feeds (typically wheat and soya) need to be added to the ghg emissions of methane from the animals themselves. Organic standards require a high proportion (60%) of feed to be forage based, either grazing or conserved (hay or silage) grass.

There is obviously a great deal more that can be said about what is a complex subject, which as Ihave said, is still lackinga wide range of good original measurements, particularly looking at different organic systems in different counties, but I hope the above will allow you to say with some confidence that at the very least, organic food is generally better in terms of lower greenhouse gas emissions.

Next, I have a few quick responses to points made by others in response to original question.  While locally sourced will usually have lower associated transport emissions (CO2), given the overwhelming significance of N2O and CH4 in agricultural emissions, we would agree with Julie Capper that ‘local’ food does not guarantee lower ghg emissions .

Three points from Simon Ward.  In organic, he is right that it is vital to look at emissions from the whole rotation – N2O emissions from the legume N-fixing part of an organic rotation should be allocated over all the subsequent arable crops (typically a two or three year red clover crop will provide sufficient N for 3 or 4 subsequent arable crops).  Simon implies that legumes are not productive (as with the reference to ‘stockless systems’ in a paper quoted above).  Leaving aside N-fixing crops like peas, beans or soya (clearly productive), in the case of clover or lucerne (alfalfa), leys are almost always used to provide two or three silage crops per annum, for beef, sheep or dairy cattle, or provide range and some feed for outdoor chickens or pigs.  These are productive crops, while fixing N and adding to soil carbon.

Simon also refers to ‘Soil Organic Matter (SOM) equilibrium’.  Of course there is a limit to how much carbon can be added to soil, but it need not concern those worried about climate change.  The biggest gains in SOM occur in the first 20 years – just when we need do most to lower ghg emissions to combat climate change.  But the long-tern Spring Barley trial at Rothamsted shows small gains in SOM from annual additions of farmyard manure (FYM) 164 years after treatment started, and show that FYM added to one plot just from 1852 to 1871 still results in slightly higher SOM than the untreated plot over 140 years later (see Figure 1 below).  The more frequent application of composted FYM in organic systems (as opposed to more frequent use of slurry or no animal manures in non-organic systems), along with the routine use of green winter cover crops, N-fixing leys, and regular return of crop residues and generally larger root mass to the soil are some reasons why organic farms increase SOM more than non-organic.15

Figure 1


 

John Kazer is, of course, right to note that other indices can be overlooked in a focus on ghg emissions, including things like the almost total absence of pesticide use in organic and the higher levels found in non-organic food,16 the 50% more numbers and 30% more species of wildlife on organic farms,17 the nearly 75% more pollinators on organic farms,18 the significantly higher levels of antioxidants and lower levels of Cadmium in organic food,19 the 32% more jobs on organic farms,20 and so on.  However, given the overwhelming importance of tackling climate change, and the minimal action taken so far by the farming and food industries to cut ghg emissions (compared to other comparable sectors like energy generation or transport), the Soil Association believes a much stronger focus on cutting ghg emissions from farming and food is long overdue, and we welcome the fact that the UK’s Climate Change Commission will focus on farming in their work in 2015.

Will - on a different but of course strongly connected point, you asked about evidence of interventions which have succeeded in changing diets. Since 2003, the Soil Association in the UK has run a programme called Food For Life, consisting of a Food For Life Partnership programme in schools, and a Food For Life Catering Mark covering nurseries, universities, workplaces, cafes, restaurants, hospitals and care homes. Evidence that the Food For Life Partnership work in schools changes what children (and their parents) eat has been published in peer reviewed journals. For example, after two years, in Food For Life schools 28% more primary school children were eating five portions of vegetables and fruit a day. Uptake of free schools meals had increased by 13% in primary schools, 20.9% in secondary schools, and by 21% across the board in schools achieving our Silver or Gold award. An increase in free school meal uptake is a good indicator of a move from what has been found to be unhealthy meals brought in to schools compared to school meals. The impact of the programme was highest in the most disadvantage areas. The most surprising result was 45% of parents of children in these schools reporting that they had changed their diets.

The Food For Life Catering Mark aims to encourage healthier, more environmentally sustainable food in other settings, and along with schools in the UK, the Food For Life mark now covers nearly 1 million meals served each working day. The Food For Life mark has been recognised by the Department of Education, the Department of Health and the Department of Environment, Food and Rural Affairs as a sign of good or excellent food provision, and is supported by the Scottish Government. Full details of the Food For Life work in schools and wider catering can be found at http://www.foodforlife.org.uk/ and http://www.sacert.org/catering.

The Food For Life Partnership and Catering Mark works at three levels, Bronze, Silver and Gold, starting with majority of food being freshly prepared and all meat being fully traceable and being produced to UK standards, with points being awarded to achieve Silver and Gold which cover local sourcing, higher environmental and animal welfare standards (like the RSPCA’s Freedom Foods or Marine Stewardship Council fish), some organic (5% at Silver and 15% at Gold), and various steps that encourage healthy eating - from the standard provision of fresh water to encouraging menus with less meat overall. You will see on the Food For Life website that Gold standard meals have been found to have a lower carbon footprint, which comes primarily from reducing meat consumption.

I hope all this is helpful.

References
 

  1. http://www.sciencedirect.com/science/article/pii/S0167880900002978
  2. Williams, A G; Audsley, E and Sandars, D L (2006) Energy and environmental burdens of organic and non-organic agriculture and horticulture. In: Atkinson, C; Ball, B;Davies, D H K; Rees, R; Russell, G; Stockdale, E A; Watson, C A; Walker, R and Younie, D (Eds.) Aspects of Applied Biology 79, What will organic farming deliver? COR 2006, Association of Applied Biologists, pp. 19-23 – http://orgprints.org/10160/See also http://randd.defra.gov.uk/Document.aspx?Document=IS0205_3958_EXE.doc
  3. (Green PigDefra; The environmental consequences of using home-grown legumes as a protein source in pig diets (Green Pig); Project No.  LK0862and the Poultry LCALeinonen I, Williams AG, Wiseman J, Guy J, Kyriazakis I. Predicting the environmental impacts of chicken systems in the UK through a Life Cycle Assessment: egg production systems. Poultry Science 2012, 91(1), 26-40 http://ps.oxfordjournals.org/content/91/1/26
  4. Kustermann et al (2008) ‘Modelling carbon cycles and estimation of greenhouse gas emissions from organic and conventional systems’, Renewable Agriculture and Food Systems,23(1) 38-52 http://www.researchgate.net/publication/231904442_Modeling_carbon_cycles_and_estimation_of_greenhouse_gas_emissions_from_organic_and_conventional_farming_systems
  5. A. Gattinger, A. Mueller, M. Haeni, C. Skinner, A. Fliessbach, N. Buchmann, P. Mäder, M. Stolze, P. Smith, N. El-Hage Scialabba, and U. Niggli (2012)Enhanced top soil carbon stocks under organic farming, Proceedings of the National Academy of Sciences
  6. Skinner, C, A. Gattinger, A. Mueller, P. Mäder, A. Fliessbach, R. Ruser, and U. Niggli 2014 Greenhouse gas fluxes from agricultural soils under organic and non-organic management – a global meta-analysis. Science of the Total Environment, 468-469, 553-563
  7. Seufert, V., Ramankutty, N. and Foley, J. A. (2012) ‘Comparing the yields of organic and conventional agriculture’, Letter –Nature http://sa.indiaenvironmentportal.org.in/files/file/organic%20%26%20conventional%20agriculture.pdf
  8. Seufert, V., Ramankutty, N. and Foley, J. A. (2012) ‘Comparing the yields of organic and conventional agriculture’, Letter – Nature http://sa.indiaenvironmentportal.org.in/files/file/organic%20%26%20conventional%20agriculture.pdf, beef or lamb http://www.fcrn.org.uk/research-library/agriculture/organic/england-and-wales-under-organic-agriculture-how-much-food-could-be-produced.
  9. As suggested by Cassidy et al, (2013) ‘Redefining agricultural yields: from tonnes to people nourished per hectare’Environ. Res. Let.8: http://iopscience.iop.org/1748-9326/8/3/034015
  10. see Pretty et al (2000) ‘An Assessment of the Total External Costs of UK Agriculture‘Agricultural Systems,65(2) – 113-136 http://www.julespretty.com/wp-content/uploads/2013/09/1.-AgSyst-pdf
  11. http://www.pesticides.gov.uk/Resources/CRD/Migrated-Resources/Documents/P/Pesticides-Forum-AR-2011-revSep12.pdf
  12. https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/372755/UK_Wild_birds_1970-2013_final_-_revision_2.pdf
  13. 2012 data – see https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/285187/agindicator-dd1-27feb14.pdf
  14. http://www.soilassociation.org/LinkClick.aspx?fileticket=qm0ueyxHQjI%3D&tab%20id=313 , 'Not all meat is equal - the case for grass fed beef and lamb, Peter Melchett and Richard Young, in 'Nutrition and Climate Change: Major Issues Confronting the Meat Industry' (Langford Food Industry Conference Proceedings) JD Wood (Ed) (Author), JD Wood (Editor) , Nottingham University Press, 2011; pp 123-138
  15. Soil Association (2009) Soil Carbon and organic farming: A review of the evidence of agriculture's potential to combat climate change. http://www.soilassociation.org/LinkClick.aspx?fileticket=BVTfaXnaQYc%3d&tabid=574
  16. Baranski et al (2014) ‘Higher antioxidant concentrations and less cadmium and pesticide residues in organically grown crops, a systematic literature review and meta-analysis,British Journal of Nutrition, http://www.ncbi.nlm.nih.gov/pubmed/24968103
  17. Tuck et al, (2014) Land-use intensity and the effects of organic farming on biodiversity: a hierarchical meta-analysis', is published in the Journal of Applied Ecology,Bengtsson, J., Ahnstrom, J. and Weibull A-C. (2005) ‘The effects of organic agriculture on biodiversity and abundance: a meta-analysis’ Journal of Applied Ecology, 42(2), 461-269
  18. Kennedy et al, Ecology Letters, (2013) 16: 584–599
  19. Baranski et al (2014) ‘Higher antioxidant concentrations and less cadmium and pesticide residues in organically grown crops, a systematic literature review and meta-analysis,British Journal of Nutrition, http://www.ncbi.nlm.nih.gov/pubmed/24968103
  20. See our report ‘Organic Works’ http://www.soilassociation.org/LinkClick.aspx?fileticket=60CVIT1Nw0U%3D&tabid=387

Will Nicholson's picture
Submitted by Will Nicholson on

Thanks for the input.  

So a general approach that "the complexity overshadows the dichotomous conventional vs organic debate" would be a reasonable position to take?  

When I work with, for example, a canteen, I am quite careful to make sure they know that (1) these are estimates, not carbon accounting results and (2) I am not differentiating between conventional and organic.  As such, it seems reasonable for a canteen to make changes to its food policy that reduces the carbon footprint that we estimate, and this can be seen in terms of "reducing their climate change impact by the estimated equivalent of 100,000km in a car" for example.  But it sure does annoy the organic movement, but I'm sure I can live with that.  

Thanks very much for the guidance.  Long live FCRN's forum ;-)

Will.

christianjreynolds's picture
Submitted by christianjreynolds (not verified) on

Hi Will,

 

I know the the UK IO tables on EORA (www.worldMRIO.com) have organic and coventional farming with carbon (GHG-e) accounts. PM me if you want to talk it through how to access/use the data.

Cheers

Christan

Simon Ward's picture
Submitted by Simon Ward (not verified) on

Will

In my experience your comments are valid both in terms of overlapping range but also in terms of the meat/veg balance. I suggest that one of the issues to address is that few farms produce a single product and products tend to be interdependent. This means that there is an allocation problem that may be agreed as far as convention is concerned but misleading in terms of the sustainability objective. A wheat crop will require nitrogen and the direct emission from the soil is approximately similar however sourced. In addition within a bit, yield is proportional to nitrogen availability. The indirect emission is far more complex since the nitrogen may be from 1) artificial sources 2) crop legumes 3) livestock manure. Source 1 is relatively high in energy and as importantly the hydrogen is sourced by splitting natural gas with a carbon dioxide coproduct and thus results in high emission (although declining - originally a lot of the energy was HEP and hydrogen produced by splitting water with an oxygen coproduct so had no GHG emission!) 2. Leads to an extraordinary waste of resources since food produced per unit of land area is very low (i.e.. across the wheat and legume area) 3. Manure is associated with an animal and while this will produce meat/milk production of food from the land area will be low (because of the feed to meat conversion) and will also be associated with a methane emission.

My suggestion are:

  1. ​Calculate emissions over the entire farm system (not individual foods) in terms of emissions per unit of food energy/protein per unit area
  2. Aim to reduce emissions by  increasing efficiency from minimizing constraints that reduce output such as disease or low fertility. There are many detailed elements that (in general) reduce emissions such as less cultivation, substitution of herbicide for cultivation, even application of fertilizer and minimization of waste.

​Finally, be aware that most agricultural systems can gain or lose carbon. Conversion arable land to grassland will usually increase carbon levels and more mundanely reduced cultivation (ignoring any additional release of nitrous oxide in some situations). However neither the gain nor the loss occurs indefinitely and a new equilibrium will eventually be reached. Thus grassland rotation is likely to have higher carbon levels than one without but the annual emission may be no different once the equilibrium is reached.

 

judecapper's picture
Submitted by judecapper (not verified) on

Will-

Totally agree re: need to have no axe to grind - not surprisingly, can be difficult to get a straight answer when talking to vehemently pro- or anti-organic factions!

In my experience (my research focuses on modeling resource use per unit of food, specifically in the beef and dairy industries) the negative impacts of lower yields in organic livestock production outweigh the positive impacts of reduced inputs, certainly in terms of land use, water use and carbon footprint per kg of milk or meat. For example, with regards to carbon footprint, transport and cropping account for <10% of the total GHG emissions per kg of milk or meat, whereas animal emissions and thus productivity (milk or meat yield, growth rate, health, calving rate etc) have a far greater impact. As such, any system that is less efficient (whether organic, low-input or simply less productive for whatever reason) tends to have greater resource use, although parameters such as biodiversity are less easy to quantify and sometimes conflict with the patterns seen in terms of resource use.

The ranges between organic and conventional may well overlap to some degree at the extremes, but given average performance of organic/low-input vs. conventional (certainly in the USA) we see a greater resource use per unit of food for organic/low-input systems - more (peer-reviewed) information available here: http://www.pnas.org/content/105/28/9668.full.pdf+html and here: http://www.mdpi.com/2076-2615/2/2/127. This is also borne out by our work comparing historical and modern production systems (http://www.journalofanimalscience.org/content/89/12/4249.full.pdf+html?sid=6d289192-fc81-483d-801e-4c80bfc6fc5c and http://www.journalofanimalscience.org/content/87/6/2160.full.pdf+html?sid=ed5f0f86-472c-4380-b84a-ef9202cbd470). 

Finally, it's worth noting that "local" (often found in conjunction with organic) foods don't always fulfill expectations with regards to environmental impact - namely lower carbon emissions per unit of food. In a comparison of grocery store vs. local farm eggs, we showed that unless the consumer lives less than two miles from the farm, mass transport has a huge environmental plus in terms of providing the means to transport thousands of units of product within one vehicle - more details available here: http://www.animalfrontiers.org/content/1/1/26.full.pdf+html

Hope this helps - or provides some points for further discussion.

Jude 

Will Nicholson's picture
Submitted by Will Nicholson on

Thanks Jude - great help.  There seems to be a strong reality gap between the romantic idea of local food produced in a supposedly low impact way, and the actual impact of our consumer behaviour!  This is maybe the problem - the "romantic" view is quite emotional, which maybe hinders real discussion?

Will.

judecapper's picture
Submitted by judecapper (not verified) on

Will-

Completely agree. I'm no psychologist, but if something fits with our beliefs, we're less likely to likely to be swayed by opposing arguments. As it seems intuitively logical that buying an apple from the farmer's market must be more environmentally-friendly than one that has traveled hundreds of thousands of miles, it's difficult to persuade people otherwise. I recently had a long conversation with a journalist about GHG emissions from grass-fed vs. corn-fed beef. After explaining the science and showing the calculations, which demonstrated that systems in which cattle take longer to finish (grass-fed) are going to be associated with higher GHG emissions (in the absence of significant carbon sequestration) per unit of beef, the journalist finally said "I get it. I understand the science and calculations. Nevertheless, I just feel that grass-fed must be better."

Whenever we get out of the science arena and into a discussion that involves faith (whether religious or relating to other beliefs, including food), it seems increasingly difficult to have good discussion.

Cheers,

Jude

elponchogtz's picture
Submitted by elponchogtz (not verified) on

Will, 

Your experience is somwehat similar to mine. In fact, during my research I performed an LCA comparing corn "tortillas" produces with organic methods and consumed "locally" vs a regular agroindustrial system. The results, as you very well put it, are very similar not only in carbon footprint but even in other impact categories!  

However, digging depper into this case I've discovered that the sustainability evaluation of each of these systems goes well beyond an LCA. An LCA, to cite my experience, is a great but limited tool. It evaluates only one particular period of time and only in a limited set of dimensions. An LCA always tries to respond "which of this systems may manufacture this good or service with the least pollution in a specific period of time?". This is not enough! If we are to assess sustainability we need to ask ourselves "does this system of production endure the test of time?" or "does this system of production create potential for beneficial co-evolution?". These are the questions that we need to look at. 

Once you look at things from this perspective you notice that agro-industrial, green revolution farming is highly dependent on external inputs, mostly based on fossil fuels, and thus cannot endure in the very long run.

An organic system may endure the test, but I'd go even further and suggest that an agroecological system is the only one that really applies human know how in the form of Ecology to create a sustainable agricultural system as defined by Pretty: "a system that puts the goods and services of nature to te best use and also nourishes the ecosystem that supports it". 

Will Nicholson's picture
Submitted by Will Nicholson on

Hi Alfonso

Thanks for your input, yeah I'd agre with you about a wider concept of "sustainable".  My interest in this case in the LCAs is to estimate the global warming contribution of food products.  However, I agree we need to take into account how sustainable something is in terms of long-term production.  

It is a shame therefore that we only have a dichotomy between organic and conventional.  Surely this is part of the problem.... we become blinded by this arbritary distinction, which makes it harder to identify what are the key elements to a sustainable food production system.


By the way, care to share the carbon footprints of "big ag" tortillas?  I know a few restaurants who use a lot of them :-)

Chris Smaje's picture
Submitted by Chris Smaje (not verified) on

Will, you say you have no ideological axe to grind, but before you've even undertaken your study you're talking about romantic views, reality gaps and emotion in relation to organic farming. So with all due respect, I surmise that you do in fact have an ideological axe to grind. It's true that people in the organic and alternative farming movements can sometimes be a bit dogmatic about favoured approaches - maybe it has to do with the endless stream of 'no axe to grind' studies negating with putative objectivity what we're trying to do. Given the pressures in the present economy to substitute labour for diesel, expand in scale and export labour-intensive forms of agriculture abroad, I don't doubt it's possible to show that conventional farming can have lower emissions than organic. But those pressures are a human artifice. Suppose governments adopted strong anti-monopoly measures, such as the need for 75% of all food to be produced within 100 miles of its point of sale, and decided to internalise the costs of fossil fuels, setting a price of say £100 per litre of diesel. Then you'd probably find that the extraordinary waste of resources involved in conventional livestock and feedstock farming would vanish, and that a surprising amount of fertility was created through the application of human labour to farming. I don't necessarily expect people to agree with such policy measures - the point is that there's no such thing as a 'no axe to grind' study. If you  advise people to go with one extant agricultural method over another on some given metric, you're probably advising them wrongly because you're looking at the past and not the future and you're probably not modelling other variables with future uncertainties properly addressed. I'd suggest that you think carefully about why you invoke the notion of a 'romantic' view of organic agriculture, and what exactly your problem is with it, and that you look at the many forms production that indeed go beyond the 'organic' vs 'conventional' duality.  

Will Nicholson's picture
Submitted by Will Nicholson on

Hi Chris, sorry, bad phrasing on my behalf. The "romantic" comment reflected a frustration about - like you say yourself - the overly dogmatic approach we sometimes see (and that is not unique to this topic of course).

I agree with you in terms of "everything would change" in the circumstances you describe, of course.

If you remember from my original post, one thing I may not have made clearer is that I do actually promote organic produce in restaurants, simply because it does represent lower impact production methods, but I wish there was more information available, rather than an organic/non-organic dichotomy.  Because it seems very unlikely that the current organic requirements have encompassed all aspects of sustainable production - life rarely works like that.

I do also work with restaurants wanting to reduce their contribution to climate change, and when they ask about organic vs conventional, it is hard to make an argument for or against either having a "better" carbon footprint.  That's where this forum post started - not an organic bashing excercise - I hope you see what I mean.

Will.

 

Peter Melchett's picture
Submitted by Peter Melchett (not verified) on

Dear Will,

I will try to answer your question (does organic food have lower ghg emissions than non-organic?), and some of the points made in subsequent comments, on behalf of the Soil Association (a UK organic organisation).  To start, I think it is worth noting two significant gaps in information about the carbon footprint of organic and non-organic food. First, although there have been quite a few Life Cycle Assessments, there is a paucity of good original data to put in to LCA models. On investigation, we have found that many LCAs simply take data from previous work.

Second - and this is a gap that the organic movement is most concerned about - currently LCAs do not take in to account losses or additions to soil carbon caused by different farming systems. Indeed, soil carbon losses are often not included in national ghg inventories. The UK for example, includes the (large) losses from lowland peat in areas like the Fens, but not soil carbon losses (or gains) from other soils. This is partly because there is little data on such carbon lossesand gains, and because they need to be measured over fairly long periods of time to get a good picture of what is really happening. In addition, at least in the UK, there is some academic dispute about whether soils (apart from exposed peat soils) are still losing carbon or not.

Overall, we do not agree with your conclusion so far, that ‘the complexity overshadows the dichotomous conventional vs organic debate’, and do not think that ‘would be a reasonable position to take’, based on the available evidence, for reasons I set out below.
 Even with the qualifications as to the quality and scope of the data used, there is no argument in the literature that organic farming in general produces less greenhouse gas emissions per hectare of production (and that is without accounting for soil Carbon losses or gains).  Generally, organic production also produces less ghgs per kilogram of production, although for some products the ghg emissions will be similar for organic and non-organic.
The clearest evidence is with energy use, as it is easiest to measure, while of course only representing a small proportion of the ghgs from farming. 

A Defra study concluded: ‘Organically grown crops require around 50% of the energy input per unit area than do conventional crops, largely because of lower, or zero, fertiliser and pesticide energy inputs. However, the generally lower yields of organic crop and vegetable systems reduce the advantage to organic when energy input is calculated on a unit output basis. In stockless arable crop rotations, the inclusion of fertility building crops and winter cover crops, that have energy inputs but no direct outputs, can result in lower whole-rotation energy efficiency from organic methods. In livestock systems, where the fall in output may be less than in arable, and there are no dedicated fertility building crops, overall energy efficiency is greater in organic than in comparable conventional systems.’  While there are some stockless organic farms in the UK, they are unusual (see below).

Another study1 concluded: ‘The energy use was generally lower in the organic than in the conventional system, but yields were also lower. Consequently, conventional crop production had the highest energy production, whereas organic crop production had the highest energy efficiency... Energy use for both conventional cattle and pig production was found to be higher than that for organic production’.

The early work at Cranfield University by Williams et al2 showed that for most arable crops, organic produces less ghg emissions per kilogram of production than non-organic. However, that early work suggested that for products like poultry and eggs, ghg emissions for organic were significantly higher than for non-organic (the same was assumed to be true for pigs). More recent Defra-supported research projects3 showed that greenhouse gas emissions for organic pigs or poultry are equivalent to non-organic free-range pig and poultry systems, per kg of production, although both free-range and organic have higher ghg emissions than non-organic intensive, indoor systems. These calculations did include the relevant IPCC factors for Land Use Change (LUC) attributable to soya production in Latin America – the source of most of the protein fed to non-organic UK pigs and poultry (and indeed dairy cows), but many earlier LCAs did not. Organic soya imported in to the UK does not usually come from Latin America, but will currently come with a high ghg footprint from transport. 

However, as organic crops cannot be grown, under organic standards, on recently converted land, there will not be an LUC factor to apply.  Organic standards encourage animal feed produced on the farm, and home grown organic peas and beans are increasingly looked at as alternatives to soya.

Much more work on climate change and agriculture has been done in countries like Germany, Austria and Switzerland, than is the case in the UK.  For example, in-depth research in Germany found that organic management on a farm resulted in lower greenhouse gas emissions than conventional management at the same site. This was largely due to carbon sequestration in soils (which were being depleted under conventional management) and due to lower N20 emissions due to the absence of artificial fertiliser.4

Indeed, recent meta-analyses that have reviewed studies from all over the world show that such findings are common. One meta-analysis found that organic farms have 3.5 metric tonnes more carbon in their soils than conventional farms.5 Another found that organic farm soils emit less N20 per hectare and take-up slightly more methane.6. Whilst this study found higher emissions of N20 when the results were scaled to yield, this is likely to be lower if the N20 emissions from the manufacture and use of manufactured fertiliser are accounted for.  N20 emissions account for more than half the ghg emissions from farming. 

While organic farming also relies on nitrogen for fertility, this is fixed by legumes (typically clover or lucerne/alfalfa). While there will be N2O emissions when the nitrogen fixing part of the rotation comes to an end (typically after three to four years, but much shorter in tropical countries), these come nowhere near the N2O emissions from the regular applications of manufactured N in non-organic systems, which operate at much higher levels of N inputs.  Furthermore, while high levels of N, crucially along with high inputs of mined Phosphate, lead to higher yields for cereal crops and field vegetables like carrots or potatoes, this is not so much the case for N-fixing crops like peas or beans,7 nor generally for fruits.8

Of course, if output (yields) were measured in tonnes of edible food per tonne of non-renewable inputs per hectare, instead of simply tonnes of output per hectare (regardless of the financial, environmental or social costs of the input required to achieve a particular yield), that would favour low input farming systems like organic.9

This is a framing issue, determined by societal values and politics, not science. In the current tonnes per hectare model, for example, the cost in  millions of pounds of extracting pesticides from drinking water are ignored14 years ago the cost of pesticide contamination in drinking water was calculated to be £120 million a year.10

More recently, one case study catchment found pesticide extraction cost £96,000 a year for water which supplied 160,000 people,11 as are the social and environmental costs of the 50% (and for some previously common species 90% or more) loses of farmland birds over the last 40 years Defra farmland bird index – index for farmland bird populations has declined by more than 50% since the 1970s.12

The second most significant ghg emissions from farming come from methane – around 44% of farming’s emissions in the UK,13 and higher than that globally.  Here, grass-fed livestock, particularly extensive beef and sheep, will have a significantly lower carbon footprint, if the carbon sequestered in permanent and semi-permanent, natural and semi-natural grazing land is taken in to account.14 In non-organic systems, the higher ghg emissions associated with cereal and protein feeds (typically wheat and soya) need to be added to the ghg emissions of methane from the animals themselves. Organic standards require a high proportion (60%) of feed to be forage based, either grazing or conserved (hay or silage) grass.

There is obviously a great deal more that can be said about what is a complex subject, which as Ihave said, is still lackinga wide range of good original measurements, particularly looking at different organic systems in different counties, but I hope the above will allow you to say with some confidence that at the very least, organic food is generally better in terms of lower greenhouse gas emissions.

Next, I have a few quick responses to points made by others in response to original question.  While locally sourced will usually have lower associated transport emissions (CO2), given the overwhelming significance of N2O and CH4 in agricultural emissions, we would agree with Julie Capper that ‘local’ food does not guarantee lower ghg emissions .

Three points from Simon Ward.  In organic, he is right that it is vital to look at emissions from the whole rotation – N2O emissions from the legume N-fixing part of an organic rotation should be allocated over all the subsequent arable crops (typically a two or three year red clover crop will provide sufficient N for 3 or 4 subsequent arable crops).  Simon implies that legumes are not productive (as with the reference to ‘stockless systems’ in a paper quoted above).  Leaving aside N-fixing crops like peas, beans or soya (clearly productive), in the case of clover or lucerne (alfalfa), leys are almost always used to provide two or three silage crops per annum, for beef, sheep or dairy cattle, or provide range and some feed for outdoor chickens or pigs.  These are productive crops, while fixing N and adding to soil carbon.

Simon also refers to ‘Soil Organic Matter (SOM) equilibrium’.  Of course there is a limit to how much carbon can be added to soil, but it need not concern those worried about climate change.  The biggest gains in SOM occur in the first 20 years – just when we need do most to lower ghg emissions to combat climate change.  But the long-tern Spring Barley trial at Rothamsted shows small gains in SOM from annual additions of farmyard manure (FYM) 164 years after treatment started, and show that FYM added to one plot just from 1852 to 1871 still results in slightly higher SOM than the untreated plot over 140 years later (see Figure 1 below).  The more frequent application of composted FYM in organic systems (as opposed to more frequent use of slurry or no animal manures in non-organic systems), along with the routine use of green winter cover crops, N-fixing leys, and regular return of crop residues and generally larger root mass to the soil are some reasons why organic farms increase SOM more than non-organic.15

Figure 1


 

John Kazer is, of course, right to note that other indices can be overlooked in a focus on ghg emissions, including things like the almost total absence of pesticide use in organic and the higher levels found in non-organic food,16 the 50% more numbers and 30% more species of wildlife on organic farms,17 the nearly 75% more pollinators on organic farms,18 the significantly higher levels of antioxidants and lower levels of Cadmium in organic food,19 the 32% more jobs on organic farms,20 and so on.  However, given the overwhelming importance of tackling climate change, and the minimal action taken so far by the farming and food industries to cut ghg emissions (compared to other comparable sectors like energy generation or transport), the Soil Association believes a much stronger focus on cutting ghg emissions from farming and food is long overdue, and we welcome the fact that the UK’s Climate Change Commission will focus on farming in their work in 2015.

Will - on a different but of course strongly connected point, you asked about evidence of interventions which have succeeded in changing diets. Since 2003, the Soil Association in the UK has run a programme called Food For Life, consisting of a Food For Life Partnership programme in schools, and a Food For Life Catering Mark covering nurseries, universities, workplaces, cafes, restaurants, hospitals and care homes. Evidence that the Food For Life Partnership work in schools changes what children (and their parents) eat has been published in peer reviewed journals. For example, after two years, in Food For Life schools 28% more primary school children were eating five portions of vegetables and fruit a day. Uptake of free schools meals had increased by 13% in primary schools, 20.9% in secondary schools, and by 21% across the board in schools achieving our Silver or Gold award. An increase in free school meal uptake is a good indicator of a move from what has been found to be unhealthy meals brought in to schools compared to school meals. The impact of the programme was highest in the most disadvantage areas. The most surprising result was 45% of parents of children in these schools reporting that they had changed their diets.

The Food For Life Catering Mark aims to encourage healthier, more environmentally sustainable food in other settings, and along with schools in the UK, the Food For Life mark now covers nearly 1 million meals served each working day. The Food For Life mark has been recognised by the Department of Education, the Department of Health and the Department of Environment, Food and Rural Affairs as a sign of good or excellent food provision, and is supported by the Scottish Government. Full details of the Food For Life work in schools and wider catering can be found at http://www.foodforlife.org.uk/ and http://www.sacert.org/catering.

The Food For Life Partnership and Catering Mark works at three levels, Bronze, Silver and Gold, starting with majority of food being freshly prepared and all meat being fully traceable and being produced to UK standards, with points being awarded to achieve Silver and Gold which cover local sourcing, higher environmental and animal welfare standards (like the RSPCA’s Freedom Foods or Marine Stewardship Council fish), some organic (5% at Silver and 15% at Gold), and various steps that encourage healthy eating - from the standard provision of fresh water to encouraging menus with less meat overall. You will see on the Food For Life website that Gold standard meals have been found to have a lower carbon footprint, which comes primarily from reducing meat consumption.

I hope all this is helpful.

References
 

  1. http://www.sciencedirect.com/science/article/pii/S0167880900002978
  2. Williams, A G; Audsley, E and Sandars, D L (2006) Energy and environmental burdens of organic and non-organic agriculture and horticulture. In: Atkinson, C; Ball, B;Davies, D H K; Rees, R; Russell, G; Stockdale, E A; Watson, C A; Walker, R and Younie, D (Eds.) Aspects of Applied Biology 79, What will organic farming deliver? COR 2006, Association of Applied Biologists, pp. 19-23 – http://orgprints.org/10160/See also http://randd.defra.gov.uk/Document.aspx?Document=IS0205_3958_EXE.doc
  3. (Green PigDefra; The environmental consequences of using home-grown legumes as a protein source in pig diets (Green Pig); Project No.  LK0862and the Poultry LCALeinonen I, Williams AG, Wiseman J, Guy J, Kyriazakis I. Predicting the environmental impacts of chicken systems in the UK through a Life Cycle Assessment: egg production systems. Poultry Science 2012, 91(1), 26-40 http://ps.oxfordjournals.org/content/91/1/26
  4. Kustermann et al (2008) ‘Modelling carbon cycles and estimation of greenhouse gas emissions from organic and conventional systems’, Renewable Agriculture and Food Systems,23(1) 38-52 http://www.researchgate.net/publication/231904442_Modeling_carbon_cycles_and_estimation_of_greenhouse_gas_emissions_from_organic_and_conventional_farming_systems
  5. A. Gattinger, A. Mueller, M. Haeni, C. Skinner, A. Fliessbach, N. Buchmann, P. Mäder, M. Stolze, P. Smith, N. El-Hage Scialabba, and U. Niggli (2012)Enhanced top soil carbon stocks under organic farming, Proceedings of the National Academy of Sciences
  6. Skinner, C, A. Gattinger, A. Mueller, P. Mäder, A. Fliessbach, R. Ruser, and U. Niggli 2014 Greenhouse gas fluxes from agricultural soils under organic and non-organic management – a global meta-analysis. Science of the Total Environment, 468-469, 553-563
  7. Seufert, V., Ramankutty, N. and Foley, J. A. (2012) ‘Comparing the yields of organic and conventional agriculture’, Letter –Nature http://sa.indiaenvironmentportal.org.in/files/file/organic%20%26%20conventional%20agriculture.pdf
  8. Seufert, V., Ramankutty, N. and Foley, J. A. (2012) ‘Comparing the yields of organic and conventional agriculture’, Letter – Nature http://sa.indiaenvironmentportal.org.in/files/file/organic%20%26%20conventional%20agriculture.pdf, beef or lamb http://www.fcrn.org.uk/research-library/agriculture/organic/england-and-wales-under-organic-agriculture-how-much-food-could-be-produced.
  9. As suggested by Cassidy et al, (2013) ‘Redefining agricultural yields: from tonnes to people nourished per hectare’Environ. Res. Let.8: http://iopscience.iop.org/1748-9326/8/3/034015
  10. see Pretty et al (2000) ‘An Assessment of the Total External Costs of UK Agriculture‘Agricultural Systems,65(2) – 113-136 http://www.julespretty.com/wp-content/uploads/2013/09/1.-AgSyst-pdf
  11. http://www.pesticides.gov.uk/Resources/CRD/Migrated-Resources/Documents/P/Pesticides-Forum-AR-2011-revSep12.pdf
  12. https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/372755/UK_Wild_birds_1970-2013_final_-_revision_2.pdf
  13. 2012 data – see https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/285187/agindicator-dd1-27feb14.pdf
  14. http://www.soilassociation.org/LinkClick.aspx?fileticket=qm0ueyxHQjI%3D&tab%20id=313 , 'Not all meat is equal - the case for grass fed beef and lamb, Peter Melchett and Richard Young, in 'Nutrition and Climate Change: Major Issues Confronting the Meat Industry' (Langford Food Industry Conference Proceedings) JD Wood (Ed) (Author), JD Wood (Editor) , Nottingham University Press, 2011; pp 123-138
  15. Soil Association (2009) Soil Carbon and organic farming: A review of the evidence of agriculture's potential to combat climate change. http://www.soilassociation.org/LinkClick.aspx?fileticket=BVTfaXnaQYc%3d&tabid=574
  16. Baranski et al (2014) ‘Higher antioxidant concentrations and less cadmium and pesticide residues in organically grown crops, a systematic literature review and meta-analysis,British Journal of Nutrition, http://www.ncbi.nlm.nih.gov/pubmed/24968103
  17. Tuck et al, (2014) Land-use intensity and the effects of organic farming on biodiversity: a hierarchical meta-analysis', is published in the Journal of Applied Ecology,Bengtsson, J., Ahnstrom, J. and Weibull A-C. (2005) ‘The effects of organic agriculture on biodiversity and abundance: a meta-analysis’ Journal of Applied Ecology, 42(2), 461-269
  18. Kennedy et al, Ecology Letters, (2013) 16: 584–599
  19. Baranski et al (2014) ‘Higher antioxidant concentrations and less cadmium and pesticide residues in organically grown crops, a systematic literature review and meta-analysis,British Journal of Nutrition, http://www.ncbi.nlm.nih.gov/pubmed/24968103
  20. See our report ‘Organic Works’ http://www.soilassociation.org/LinkClick.aspx?fileticket=60CVIT1Nw0U%3D&tabid=387