The potential of organic farming to contribute to climate change mitigation

What is organic agriculture?

IFOAM definition

Organic agriculture is a production system that sustains the health of soils, ecosystems and people. It relies on ecological processes, biodiversity and cycles adapted to local conditions, rather than the use of inputs with adverse effects. Organic agriculture combines tradition, innovation and science to benefit the shared environment and promote fair relationships and a good quality of life for all involved.

4 IFOAM principles

Organic farming is based on four core principles:

Health: Organic agriculture should sustain and enhance the health of soil, plant, animal, human and planet as one and indivisible.
Ecology: Organic agriculture should be based on living ecological systems and cycles, work with them, emulate them and help sustain them.
Fairness: Organic agriculture should build on relationships that ensure fairness with regard to the common environment and life opportunities.
Care: Organic agriculture should be managed in a precautionary and responsible manner to protect the health and well-being of current and future generations and the environment.

Organic agriculture is largely rooted in agroecological approaches, both in principles and actual practices. Many organic and some innovative conventional farmers in Europe have embraced agroecological principles for the design and management of their farms. There are different schools of thought but, in short, agroecology can be defined as the use of ecological principles for the design and management of sustainable agricultural/food systems. It relies on the application of five basic principles: recycling, efficiency, diversity, regulation and synergies (Tittonell, 2014). In 2015, IFOAM EU published a report on the crucial role of agroecology in transforming the agri-food system and ensuring food security (Hilbeck and Oehen, 2015). Interest in organic farming amongst farmers has increased steadily in the EU since the mid-1980s as the farming community sees the move to organics as an attractive sustainable business opportunity. The latest Eurostat figures show organic production accounting for 6.2% of the EU’s total farmland area in 2015, covering more than 11 million hectares. At the end of same year, the EU has 271,500 organic producers – an increase of 5.4% compared to 2014 (Eurostat 2016).

Demand for organic food in EU continues to increase year-on-year. Compared whole EU food and drink sector, the EU organic food market has developed significantly over the last decade. Organic retail sales doubled from 11.1 billion euro in 2005 to 24 billion euro by 2014 with a growth of rate of 7.4% on previous year (Stolze, in Meredith and Willer, 2016).

This section addresses the potential of organic agriculture to contribute to climate change mitigation. Many of the mitigation measures in agriculture discussed in the previous section (cf. Table 8 in the Appendix) are key practices in organic agriculture and have been well established in organic systems for decades (these include lower nitrogen fertilization levels, a focus on soil organic carbon and the use of legumes in crop rotations). Other measures are not at all suited to organic agriculture, as they conflict with the underlying principles (e.g. nitrification inhibitors). Here, we will discuss the main emission categories as identified above, in relation to the key options and practices for organic agriculture. This will indicate measures that fit particularly well with organic production systems and are therefore likely to be implemented in a conversion to organic agriculture. We also point out what measures are especially problematic for organic agriculture. Most of these measures are not compulsory in the sense that they are not described in the EU’s organic regulations, but they are standard practice for those switching to organic agriculture. Theoretically, the measures could all be implemented in conventional agriculture as well. Overall, organic agriculture has considerable potential to contribute to climate change mitigation, as is shown in Table 5 towards the end of this section, which synthesizes the discussion in sections 4.1-4.5.

Measuring the performance of agricultural production systems

The key point about measuring performance and mitigation potential was expressed by Tittonell (2014), who said that “what causes global warming is the total net emission of CO2 and related gases per area, irrespective of the yields obtained. Calculating emissions or any other environmental impact per unit of produce, as often done through the methods of environmental accounting, is thus misleading. This exacerbates the sensitivity of environmental assessments to the definition of system boundaries.”

When discussing climate change mitigation in agriculture, the primary metric usually used is emissions per kilogramme (kg) of output, rather than emissions per hectare (ha). This assumes an unquestioned demand for agricultural products that should be met with the lowest possible GHG emissions. With such an approach, conventional agriculture usually performs better as the yield gap between organic and conventional production (Seufert et al., 2012) often leaves the former at a disadvantage, despite the fact that its emissions per ha tend to be lower. This is a limited view which does not allow a proper assessment of mitigation potentials across whole food systems (Niggli et al. (2009), IPES-Food (2016), Tittonell (2014)). It is important to adopt a more systemic view, since the emissions per kg of product are just one way – and not necessarily the most important way – of measuring emissions and emission reductions in agriculture.

A paper by Seufert et al. (2012) concluded that the average yield gap between conventional and organic agriculture systems across crop types and locations amounted to about 20% (Seufert et al., 2012). According to Pablo Tittonell, “a new publication that reanalysed the same data using more sophisticated statistical techniques to account for co-variances indicates that yield gaps between both systems are narrower when similar amounts of nitrogen are applied in both systems (9%), or when entire rotations were considered (7%) (Ponisio et al., 2015)”20. Tittonell also notes that, “considering long-term series rather than point measurements is important when comparing yields in both systems,” as long-term yield stability and resilience are two important aspects to consider when comparing the merits of agricultural systems, especially in light of the need to adapt to climate change.

On the question of whether to benchmark GHG emissions per land area or per product quantity, Niggli et al. (2009) point out that “environmental concerns – such as nitrate losses into groundwater or biodiversity loss through overfertilization and overgrazing – are the main rationale behind organic agriculture standards on stocking density, limiting livestock to two units per ha in most productive areas. Animal welfare is another reason, because lower stocking densities offer free movement to animals. Therefore, the very purpose of the organic paradigm is producing less livestock while increasing the share of crops for human consumption. In this respect, per area benchmarking of GHG emissions is more appropriate than per product quantity for farming system comparisons, especially in the context of climate change and livestock production” (Niggli et al., 2009).

IPES-Food (2016) highlight the role of the choice of measures and indicators as a “conceptual barrier around the way questions are framed and one of the key mechanisms locking industrial agriculture in place, regardless of its outcomes.” They point out that “research funding, development programming and political support for agriculture is often decided on the basis of specific performance indicators. Which indicators are used is therefore crucial. The performance of agriculture is often measured in terms of total yields of specific crops, productivity per worker, and total factor productivity (total outputs relative to total land and labour inputs)”, which favours highly specialized and increasingly large-scale farms, but […] “the analysis of different agricultural systems’ viability is generally carried out based on simplistic cost-benefit analysis, which does not incorporate ecological, social and cultural variables, and does not take into account the complexity of systems.” (IPESFood, 2016).

All these points show how important it is to complement efficiency measures with more systemic aspects that make it possible to address overall production levels, as well as the role certain resources play in a food systems context. The overall level of production and the resulting environmental impact are crucial. Reductions in wastage or in the consumption of animal products each offer considerable leverage for mitigation at this level. To complement “efficiency”, such approaches can be listed under the heading of “sufficiency”. Furthermore, optimal use of resources is crucial. Grasslands that can only be used to produce food from ruminants are important feed sources, although the emissions from enteric fermentation tend to be higher than for animals fed on concentrates. Such approaches of optimal resource use in a systemic context complement “efficiency” under the heading of “consistency”. These systemic aspects are explored in more detail in section 5, while the more technical farm and field-level mitigation options for organic agriculture are addressed in the following sections.

EMISSIONS FROM LIVESTOCK AND MANURE MANAGEMENT

This covers emissions from enteric fermentation in ruminants and from manure management for all animals.

ENTERIC FERMENTATION

Feed additives are not yet sufficiently well developed as a technology for practical application, and many of them are unlikely to be considered compatible with organic standards.

Feed composition clearly has an impact on enteric fermentation. The substitution of roughage feed by concentrates generally tends to reduce emissions from enteric fermentation. A higher proportion of concentrates in feed rations is also necessary to increase animals’ productivity for high milk yields of 10,000 litres or more, and for fast-growing meat animals that reach their slaughter weight at between 9-12 months. However, forage quality and fibre digestibility play a key role and well-designed roughage-based feeding rations can act in a way similar to concentrate-based feed, as was shown by Klevenhusen et al. (2011), among others. A study, carried out by the Thünen Institute for the German organic farmers’ association Bioland, compared 40 organic farms with 40 conventional farms in Germany, including a wide range of farm types. The analysis of the dairy farms in Table 3 shows that product related emissions reach similar levels, with organic emissions being lower, albeit not significantly (see Table 3).

Changing feed composition towards a higher share of concentrate feed is against the spirit of organic agriculture. The EU organic regulation already demands that 60% of the feed for ruminants should come from the farm or from the same region. The BioSuisse standard in Switzerland goes even further and has an upper limit of 10% on the use of concentrate feed. Feed should therefore primarily come from the farm or the farm region and should not be imported from abroad. Furthermore, increasing the proportion of concentrate in animals’ feed, thereby also raising the intensity of production, poses a correspondingly higher risk to animal health and welfare and has an adverse impact on the animals’ longevity. Several authors also point out that some of the dietary changes may even pose risks to human health (Martin et al., 2010, Sejian et al., 2011). Recent findings show that milk and meat derived from a roughage-based diet contain significantly more omega-3 fatty acids and less cadmium, saturated fatty acids and pesticide residues, and bring corresponding health benefits (Średnicka-Tober et al., 2016a, Średnicka-Tober et al., 2016b). Finally, the GHG balance of feed containing more concentrate is influenced by the characteristics of its production. When addressing ruminant feed, it is important to use wider systemic boundaries and to include all emissions related to feed production, namely the emissions from arable land for concentrate feed production and, if relevant, also from land use change that took place to provide areas for concentrate feed production.

There are many reasons why increasing the use of feed concentrate as a means of directly reducing enteric fermentation emissions is undesirable for organic production. These include the health and nutritional aspects described above, as well as the role of grassland and feed farming as a competitor to food production on arable land in sustainable food systems, as has already been mentioned above and will be discussed in section 5. Organic farming therefore needs other measures to help reduce emissions from enteric fermentation.

Specific practices can be used to increase the longevity and the number of lactation periods of dairy animals, which reduces the emissions per kilogram of milk. As emissions per kilogram are calculated according to the animals’ entire lifetime – including the unproductive rearing phase – the longer a cow stays within the herd, the lower the associated methane emissions on the farm (O’Mara, 2004). Importantly, by increasing the average number of lactations per animal during its lifetime from 2.5 to 5, methane from enteric fermentation decreases by around 13%. Another approach is to adopt dual-purpose breeds of cattle that provide both milk and meat. As two end-products are obtained from each animal, the emissions per kilogram of each product can be significantly reduced (Muller and Aubert, 2014).

These two measures – increased lifespan and the use of dual-purpose breeds – are particularly well suited to organic production systems, which are generally less intensive and focus more on animal health and welfare.

If changing diets and consumer behaviour expand the scope for substitution by including chicken and pork as well as beef, then per kg emissions are further reduced as these monogastric animals emit considerably less per kg product (Tilman and Clark, 2014). However, as was pointed out in the insert on measurement above and is discussed again in section 5, focusing on emissions per unit of product provides a very limited picture. For a holistic assessment of mitigation options through food production we must look at the entire food system, including consumption.

Table 3: Product-related GHG emissions from dairy production systems (gCO2-eq/kg milk). (n.s. = not significant)

Source:

Hülsbergen H-J, Rahmann G (eds.) (2015) Klimawirkungen und Nachhaltigkeit ökologischer und konventioneller Betriebssysteme – Untersuchungen in einem
Netzwerk von Pilotbetrieben: Forschungsergebnisse 2013-2014

Manure management

The storage and treatment of manure can have a very significant effect on GHG emissions. Liquid manure generates greater emissions, and the accumulation of manure in liquid form occurs more often in intensive than in organic livestock systems, as in the latter more bedding material is usually mixed in with the manure. Improved manure stock structure and management can reduce nitrous oxide and methane emissions by 50% and 70%, respectively. A technique often used in organic agriculture, and in biodynamic agriculture in particular, is manure composting. This can result in similar reductions, with about 50% less nitrous oxide and 70% less methane (Pardo et al., 2015). When emissions derived from the application of this compost are measured, they can be somewhat lower than for normal manure. On the other hand, manure composting can increase ammonia emissions leading to 50-120% higher indirect nitrous oxide emissions (Pardo et al., 2015).

However, viewed across the whole life-cycle from production to application, composting manure has the potential to reduce the emissions associated with manure management. It must be emphasized, that these results are derived from only a small number of studies, so further GHG measurements are needed to fully appreciate the climate relevance of composting.

Another option, which seems promising, is the small-scale production of biogas from manure, with the slurry used as fertilizer on the fields. Attention must be paid to avoid a competition between food and biogas with, for instance, energy crops specifically grown for use as a biogas substrate (e.g. maize in Germany). Furthermore, the use of biogas slurry as a fertilizer on fields does not always meet with acceptance, and may even be excluded by certain regulations. Guidelines have been developed for the best ways of producing biogas on organic farms21, and the discussion continues (Gerlach et al., 2013).

Emissions due to mineral nitrogen and synthetic fertilizers

There is a direct correlation between the nitrous oxide (N2O emissions generated by nitrogen fertilizer applications and the amount of nitrogen (N) applied. In this respect, reducing nitrogen applications is the most effective way of achieving emission reductions. Agricultural land in the EU is usually overfertilized so there is a general potential to reduce the rates of application. On organic farms, nitrogen levels per hectare tend to be lower than on conventional farms due to the ban on mineral nitrogen fertilizers, the focus on closed nutrient cycles and the efforts to minimize losses through runoff, volatilization and emissions. Livestock densities also tend to be better adapted to the resources available on the farm itself, then is the case with conventional farms. Correspondingly, nitrous oxide emissions tend to be lower on a per hectare basis.

Due to the yield gap between organic and conventional agriculture, nitrogen emissions per kilogram tend to be higher in organic than conventional agriculture. Tuomisto et al. (2012), for example, report about 30% lower median nitrous oxide emissions per area in organic systems, while the impact per unit of product was 8% higher than in conventional farming systems. This refers to direct nitrous oxide emissions from fertilized soils, but the picture is similar for indirect emissions stemming from volatilization and runoff, mainly as ammonia. Here, Tuomisto et al. (2012) report 18% lower ammonia emissions per ha, but 11% higher emissions per kg product. However, Meier et al. (2015) identified inconsistencies in the nitrogen balances in most of these studies, concluding that the life-cycle assessment (LCA) models underlying them do not adequately capture nitrogen dynamics in organic systems and may overestimate emissions on a per kg product basis. Part of the nitrogen flows are overestimated in the common LCA models, which are not adequately adapted for the specific characteristics of organic fertilizers and organic production systems. Correcting for this, they also found that the per kg product emissions are not necessarily higher in organic systems.

The most recent study of soil-borne emissions in organic and conventional systems, based on experimental system comparisons, reports a similar pattern (Skinner et al., 2014). They find that the higher emissions per kg product in organic agriculture would vanish if the yield gap drops below 17%, which is not very far from the yield gaps reported in recent all-encompassing meta-studies by Seufert et al. (2012) and others (cf. footnote 28). Skinner et al. (2014) also report a significantly higher methane uptake in organically managed soils, but it is only a small effect and data is scarce. Focusing on Mediterranean climates, Aguilera et al. (2013b) find nitrous oxide emission reductions of up to almost 30% in organic production systems on a per ha basis, but they do not report on emissions per yield.

Reducing nitrogen applications has additional benefits if it is achieved through the reduction of mineral fertilizers, as this results in a corresponding reduction of emissions from fertilizer production. Referring to the numbers from the previous section, abandoning the use of mineral nitrogen fertilizers altogether in the EU – as would be the case with full conversion to organic agriculture – would result in an 18% reduction in total agricultural emissions in the EU (not accounting for the yield reductions that could arise from this, cf. below). In terms of the EU GHG inventories and targets, such reductions would be accounted for under industry, which also includes fertilizer production.

With such a reduction in mineral fertilizer use, total nitrogen input levels would fall. Given that mineral fertilizers account for 45% of total N inputs to agriculture in the EU (Eurostat, 2016a), this has the potential to reduce soil-borne N2O emissions by 45% as well – i.e. about 20% of total agricultural emissions. As this might not be possible without adding alternative sources of nitrogen (increased legume cropping), for an indicative illustration, we may only assume a reduction of half this amount after the additional N-fixation in legumes – i.e. about 10% of total agricultural emissions.

The development of organic farming therefore offers good potential for reducing overall nitrogen levels in agriculture. Furthermore, there are indications that mineral fertilizer applications adversely affect soil organic carbon levels (IFOAM EU, 2015b).

GREATER SOIL ORGANIC CARBON SEQUESTRATION IN ORGANIC FARMING

Organic agriculture is associated with higher carbon sequestration as many organic practices help to improve soil quality and carbon sequestration. The most common organic practices that increase soil organic carbon are the use of organic fertilizers (such as the composted waste products from livestock husbandry), crop rotation involving legumes and the planting of cover crops (Bellarby et al., 2008, Gattinger et al., 2012, Muller et al., 2011).

A meta-analysis by Gattinger et al. (2012) indicates that significant differences exist between organic and conventional farms, in terms of their soil organic carbon stocks and sequestration rates. The authors emphasize that the main changes in soil organic carbon result from commonly applied practices in organic agriculture, such as improved crop varieties, extended crop rotations and the application of organic fertilizers like composted waste from livestock husbandry. The meta-analysis shows that soil organic carbon stocks in the upper 20 centimetres of soil are significantly higher in organic systems than under non-organic management practices (by 2.5-4.5 tonnes of carbon per hectare). The analysis also shows a mean difference in annual carbon sequestration ranging from 0.9 to 2.4 tCO2-eq per hectare (net sequestration in the top soil), or from -0.35 to 2.35 tCO2-eq per hectare for closed systems where no biomass is imported from outside. In another meta-analysis, Tuomisto et al. (2012) compared the environmental implications of organic farming in the European Union and showed that soil organic matter content was 7% higher on organic than on conventional farms. One of the main reasons for this is that organic matter inputs (manure or compost) were on average 65% higher.

Table 4: Benchmark values in conventional farming for crop-specic changes in soil organic carbon stocks expressed in CO2-equivalents (t CO2-eq/ha/yr)

Souce: Muller et al., 2011, page 24, based on VDLUFA, 2004

How much carbon the soil is able to sequester depends mainly on the quantity of organic matter applied, although the type of organic matter also seems to play a role22. Gains in soil organic carbon sequestration are highest for compost, with raw manure adding over a tonne of carbon less per ha and year (Aguilera et al., 2013a). Furthermore, certain crops have a bigger impact than others, with legume crops clearly adding more to the soil organic carbon stocks (see Table 4). Besides the supply of organic matter and the planting of legume crops, which are both key features of organic farming, crop rotation as commonly practised on organic farms can also increase soil organic carbon stocks by about 0.8 tCO2-eq/ha per year, compared to monoculture practices (Muller et al., 2011, based on West and Post, 2002, and Smith et al., 2008).

Soil organic carbon stock is important not only because it has the potential to sequester large amounts of carbon, but also because it maintains soil productivity, structure and soil life. These important soil attributes improve plant health, water holding and retention capacity, resistance against droughts and other extreme weather events, and contribute to the maintenance and development of yields (Lorenz and Lal, 2016, Muller et al., 2011).

In many EU countries, soil carbon levels are actually declining in arable and horticultural farmland. Intensive agriculture is linked to ongoing soil degradation, soil carbon losses and a possibility of declining future yields. A study and review of a 50-year US agricultural trial found that the use of synthetic nitrogen fertilizer resulted in an average loss of around 10,000 kg of soil carbon per hectare and the loss of all crop residues. The higher the application of synthetic nitrogen fertilizer, the greater the amount of soil carbon lost as CO2 (Khan et al., 2007, Mulvaney et al., 2009).

Applying the sequestration rate in closed systems referred to above, Gattinger et al. (2012) show that converting from conventional to organic agriculture on the available arable land in the EU would lead to the sequestration or reduced loss of 110 MtCO2-eq per year, which would offset around 25% of the EU’s total agricultural emissions. However, the process of sequestration is not unlimited. After a few decades, soils would be in equilibrium and the annual rate of sequestration would decrease, eventually reaching zero in about 30-40 years. Thus, we can derive an indication of the cumulative sequestration potential as follows. We assume that the soil carbon sequestration rate drops linearly to half its value over 15 years, after the conversion from conventional to organic agriculture. We also assume a more or less constant level of EU agricultural emissions of about 465 MtCO2-eq for a baseline projection without further conversion to organic agriculture until 2030, as forecast by Van Doorn et al. (2012). Under these assumptions, the cumulative soil carbon sequestration potential until 2030, derived from an immediate conversion to 100% organic agriculture, corresponds to about 18% of the cumulative agricultural emissions in the EU up to 2030, against the baseline without conversion to organic agriculture.

These estimates for the mitigation potential of soil carbon sequestration under conversion to organic agriculture can be compared to the estimates of the mitigation potential from carbon sequestration in general. This is derived by applying a range of different agricultural practices in conventional agriculture, rather than focusing on the conversion to organic agriculture. It is presented, for example, by the European Commission (2016e). Earlier similar assessments of the general sequestration potential judged the theoretical potential to be quite high, at up to 200 MtCO2-eq per year, if applied to all agricultural land in the EU (including arable land and grasslands)23. However, this has been contested as unrealistic, with the effectiveness of some measures called into question (e.g. no-till and reduced tillage). Moreover, other factors such as water availability can further restrict this potential. More recent studies – based on more detailed models of soil carbon dynamics and addressing economic constraints – report lower numbers ranging from 10-40 MtCO2-eq/year (Lugato et al. (2014), Frank et al. (2015) cf. European Union (2016). Thus, the soil carbon sequestration potential of arable land can be realised through a combination of practices (mainly optimised crop rotations, organic amendments, partly improved tillage), which can be applied in both conventional and organic contexts but are well established and implemented in organic agriculture.

In organic systems, due to weed pressure it is harder to realise the sequestration potential of reduced tillage – if such potential exists at all. Research on this is ongoing and results so far show no clear trend regarding the suitability of this management approach in organic systems (Mäder and Berner, 2012). In conventional agriculture, crop rotations and reduced tillage or no-till approaches are most relevant, while the optimal use of organic amendments is less common.

Organic agriculture represents a production system in which optimized crop rotations and organic fertilizers, such as compost and manure, and the use of mulches are combined optimally. Recent research comparing conventional and organic production systems at 80 reference farms in Germany has shown the optimal nature of organic farms with regard to soil carbon sequestration. Although emissions from enteric fermentation are higher per kg product on organic farms, due to the greater proportion of roughage fed to the animals, this is compensated by the increased soil organic carbon sequestration, both on the land used for feed production and in the avoidance of land use change emissions (Hülsbergen and Rahmann, 2015). Due to the mitigation effect of soil carbon sequestration, conventional and organic dairy farms show similar overall emission levels (cf. section 4.1.1).

Other aspects of crop and livestock production

Enteric fermentation, manure management, nitrous oxide emissions from fertilized soils and emissions from mineral fertilizer production comprise the most important emission categories. However, there might also be openings for reductions in other areas. In the EU-28 plus Iceland, the major opportunities occur in the production of plant protection chemicals and the use of energy.

Global emissions from the production of plant protection agrochemicals are equal to about a tenth of the emissions from mineral fertilizer production (Bellarby et al., 2008), but these are uncertain estimates. Such emissions are avoided in organic agriculture, since the use of these products is banned. However, some replacement treatments are allowed in organic production, and the production emissions related to these must be accounted for as well, which somewhat lowers the reduction potential from banning pesticides.

Besides on-farm energy use, transport energy is also relevant. Some organic labels include regulations on transportation of agricultural products. The Swiss private organic label “Knospe”, for example, excludes unnecessary transportation of agricultural products by air, thereby saving further CO2 emissions.

As a rule, organic agriculture performs better than conventional agriculture regarding energy use, measured both per hectare and per product (Reganold and Wachter, 2016, Meier et al., 2015). The meta-analysis of Tuomisto et al. (2012) similarly states that median energy use per product unit in organic systems is about 20% lower than for conventional farming practices, and the review by (Scialabba and Muller-Lindenlauf, 2010) found that organic agriculture consumes around 15% less energy than conventional agriculture, per unit produced. These differences arise mainly because the production and transportation of inorganic fertilizers require large energy inputs, which are not needed in organic farming since they are prohibited. Consequently, the GHG emissions associated with the production and use of inorganic fertilizers are also absent from the organic farming system (see above). In integrated agricultural farming, for example, Deike et al. (2008) found that about 37% of the total energy inputs consisted of the fossil fuel consumption entailed by mineral fertilizer production and application. On the other hand, Gomiero et al. (2008) highlight the fact that the differing energy inputs for organic and conventional production largely depend on the products being considered, and the results do not always indicate a clear trend. They showed, for example, that organic agriculture consumes between 9.5% (apples) and 69% (milk) less energy than conventional farming. Other studies of the meta-analysis indicate a 7% to 29% higher energy consumption for organic potato production, compared to conventional farming (Gomiero et al., 2008). Here again, the newer and more detailed analysis of Meier et al. (2015) gives a somewhat clearer picture. The energy use per unit of product is lower for livestock products and arable crops, while it is mixed for fruits and vegetables.

OTHER ASPECTS OF CROP AND LIVESTOCK PRODUCTION

On-farm energy use mainly involves heated greenhouses, farm machinery and irrigation, as considerable amounts of energy are required for pumping water. Emissions from heated greenhouses (with non-heated renewable energy) generally do not occur in organic agriculture, as many labels prohibit them (e.g. Demeter or Naturland). Emissions from machinery and irrigation are not necessarily lower in organic farming, although the improved soil fertility, higher water holding capacity and water use efficiency could mean the irrigation needs and corresponding energy use are lower. Besides on-farm energy use, transport energy is also relevant. Some organic labels include regulations on transportation of agricultural products. The Swiss private organic label “Knospe”, for example, excludes unnecessary transportation of agricultural products by air, thereby saving further CO2 emissions.

SummariSing remarks

Organic agriculture has significant potential to help mitigate climate change. Based on the figures in the assessment above, by 2030 soil carbon sequestration and the avoidance of mineral fertilizers in organic agriculture could reduce or offset emissions equivalent to about 35% of total agricultural emissions in the baseline projections, for which the emissions are now forecast to stay at around 465 MtCO2-eq per year till 203024.

This assessment assumes an immediate conversion to 100% organic agriculture. Assuming a 50% conversion of EU arable land to organic production (i.e. an additional 44 percentage points to the current 6%), this would result in the mitigation of about 17% of the EU’s cumulative agriculture emissions up to 2030. Given that such conversion would not happen within one year, we may assume a linear increase to this 50% share in 2030, which produces a cumulative mitigation effect of about 8-9% for the whole period to 2030, based on soil carbon sequestration (contributing about 5.5%)25 and reduced mineral fertilizer production (contributing 4-5%).

Such a conversion would entail a corresponding reduction of nitrogen inputs on the fields, and therefore bring additional emission reductions due to the reduced amount of N2O emitted by fertilized soils. As soil-borne N2O is about 40% of total agricultural emissions and mineral N is about 45% of total N applied in the EU, a linear increase in conversions to organic agriculture to 50% by 2030 would result in additional cumulative reductions of about 4-5% of EU agricultural emissions. In this calculation, we assume that the reduction in mineral fertilizer use when converting to 50% organic agriculture would not be compensated by additional N inputs26. This is however unrealistic, given the higher share of legume cultivation in organic agriculture. Nevertheless, overall N levels would decline, and a realistic lower estimate of the cumulative reduction in emissions due to a 50% conversion would be 12-14%, derived from increased soil organic matter and reduced production and application of mineral N fertilizer up to 2030. These figures are presented in Table 5.

We stress the caveat that yield levels would probably fall to some extent with such a change, thus necessitating a reduction in exports or a corresponding change in consumer behaviour, be it a reduction in food wastage or the lower consumption of animal products.

Table 5: Summary of the potential CC mitigation eects of organic agriculture, based on a scenario of linear increase towards 50% organic agriculture in the EU-28 plus Iceland by 2030. Percentages are in relation to the EU-28 plus Iceland future agricultural BAU emissions till 2030 as projected in van Doorn et al. (2012) or, similarly, in relation to the somewhat lower emissions in the baseline 2005 (Danila et al., 2016); Dierences in percentages reduction potential if related to one or the other of these two base values is negligible given the uncertainties of these numbers, at less than 0.7%.

Source: Own calculations based on the discussion and references presented in section 4

In 2030, if organic agriculture has achieved a 50% share of total production, the lower mineral N levels would result in 9% lower production emissions and N2O emissions from fertilizer application would fall by 10%, though this would be counteracted in part by the increased cultivation of legumes. Soil carbon sequestration would continue to occur, but at a decreasing rate. Altogether, this would offset about 32-34% of agricultural emissions in the year 2030, or about 12-14% of cumulative emissions till 203027, assuming that these developments were accompanied by behavioural changes to reduce food wastage and the consumption of animal products, thereby compensating for the likelihood of lower yields from organic production.

SOME OBSRVATION

While they are core features of organic farming, many of the practices that help reduce emissions or increase carbon sequestration in organic agriculture could well be used in conventional agriculture too. This is evident, for example, in the list of general mitigation practices for agriculture presented by the IPCC (Smith et al., 2007) (see also Table 8 in the Appendix). This is important, as it demonstrates the potential of organic practices for climate change mitigation in agriculture in general. It shows that organic agriculture can serve as a best practice example and blueprint to increase the sustainability of agriculture in general.

When assessing the potential emission reductions from conversion to organic agriculture, it is important to adopt a systemic perspective. Such a conversion avoids mineral fertilizer production, but, as mentioned, it also results in an average 20% decline in yields (Seufert et al., 2012)28. Without a change in overall demand, this would effectively offset the emission reductions as the missing produce would have to be produced on additional domestic cropland or imported from abroad. Furthermore, organic agriculture entails a larger share of legumes in crop rotations, which will also be reflected in human diets, unless legumes are mainly grown for animal feed. The conversion to organic agriculture therefore has a considerable potential to reduce GHG emissions from agriculture, if it is combined with dietary changes that lead to a reduction in food wastage and lower consumption of animal products (Schader et al., 2015, Muller et al., 2016). To complete the picture, an analysis of organic agriculture must be complemented by an assessment of the sufficiency and consistency of entire food systems, focusing on the total production level and optimal resource use across the whole system. Such an all-encompassing food-system approach shows how organic agriculture can play a significant role in sustainable food systems that ensure food security while contributing to climate change mitigation. We should also keep in mind that, as discussed in section 5, organic farming systems are more resilient to changing weather conditions and often significantly outperform conventional systems in conditions of extreme drought.

We would stress the importance of the entire-food-systems perspective, in particular in contrast to common life-cycle analyses that focus on (eco-)efficiency and per-unit product emissions. We reiterate the point that efforts to reduce GHG emissions in agriculture should do more than just address agricultural production and assess the relative performance of organic and conventional approaches, for example, on a per-unit basis. Livestock feed should be analysed systemically, as the role of grassland can support different arguments than GHG emission levels per kg product. The yield gap plays a significant role in system comparisons based on emissions per kg, but it is less important if the reduction of food wastage becomes an option, i.e. the reduction of total agricultural output. Such a measure on food system rather than farm level considerably reduces the importance of the yield gap as the total emissions of an overall smaller production system can still be lower, even if emissions per unit of produce are higher. The reduction of animal products in human diets can be assessed along similar lines, in particular if it is achieved through a reduction in concentrate feed and focuses on grassland-based ruminant production and monogastrics (e.g. pigs) being fed by-products from food processing and crop residues. Such a system would also result in lower demand for agricultural products (as it would largely avoid the need to use arable land for feed crops), and in turn reduce the pressure to close the yield gap.

Clearly, reducing the yield gap and increasing organic yields would reduce emissions still further, but in a systemic view the yield gap relates to “efficiency”, which is only one criterion for assessing sustainable food system – in other words, the relative resource-use or impact per kg product. At least as important as this are the total consumption levels, as reducing these clearly also reduces emissions (whether because of the reduced wastage, or the reduced animal feed production and correspondingly lower quantities of animal products). This relates to “sufficiency”. Finally, the role various resources play in the food system is similarly important. Grassland, for example, can only be used in the production of food for humans by keeping ruminants. It might therefore make sense to focus on grassland-based ruminant production while reducing the amount of concentrate feed fed to them, although this could increase emissions per kg product. This relates to “consistency”, which addresses the question of the roles different resources play in the context of a sustainable food system. As such, it helps to indicate viable paths towards increased sustainability.