Organic in Meeting climate change and food security challenges

Local authorities and farming sector knowledge and action Editorial carbon: what are the issues for climate and GIS Sol agriculture? in brief

Jérôme Mousset Created in 2001, GIS Sol Head of the agricultural (sol being the French and forestry service, ADEME

T. P. word for soil) is a French scientific network focused Soil is the living base for agricultural and forestry on soils. The network production and a limited resource which cannot be includes the French National Institute for renewed at the human scale. Increasingly, land is in Agricultural Research demand and there is tension between different land (INRA), the French uses. Changes in production practices, ploughing Environment and Energy up of grassland, loss of arable and wooded land for Management Agency urbanisation, increased use of ...There are (ADEME), the Ministry of Agriculture, Food and so many changes which, if not taken into account, Forests, the Ministry could affect soil quality and lower stocks. of Ecology, Sustainable Nevertheless, soil is a considerable asset in strategies Development and Energy, for mitigating climate change. But this issue lacks the Institute of Research visibility and, in order to raise awareness among for Development (IRD) and the National Institute territorial administrators, decision makers, farmers for Geographical and and foresters, ADEME has enlisted the help of experts, Forestry Information scientists, advisers and representatives of public (IGN). authorities to produce this brochure. GIS Sol is seeking to This brochure aims to clarify the role of soil in mitigating create and manage an information system on the greenhouse effect and, furthermore, to highlight French soils, including the environmental benefits of better management data about their spatial of . A healthy, living, well-balanced soil distribution, their containing organic matter can increase production characteristics and potential, contribute to optimising the use of agricultural changes in their quality. It works in the knowledge inputs, filter water from these pollutants and increase that soil is a limited and biodiversity. This idea of environmental and economic non-renewable resource services chimes exactly with the principles of at the human scale. agroecology.

2l Soil and carbon Contents

Issues Points of view 04. Soil, a carbon pool essential for the 20. Reconstructing carbon stocks climate Many benefits to highlight 06. Continuously providing soil with Evaluation organic matter 22. Measuring changes 08. Organic matter: providing at the field scale environmental services 24. Measurement tools Points of view at the territorial scale 10. Carbon storage in soils: Perspectives rising awareness 26. Improving and sharing references Impacts and levers for action 27. An international dynamic 12. Changes in land use: the need to combine food security and climate to preserve carbon-rich soils change mitigation 14. Forest soils: rationalising the Research increase in harvested wood 28. ADEME supports research 16. Agricultural soils: acting on organic for better agricultural and matter inputs and losses environmental management of 18. Agricultural practices according to their cost 30. Soil organic carbon matters and efficacy in the European Union

This document has been edited Communication service: Brochure Ref.8575 to download on by ADEME Sylvie Cogneau www.ADEME.fr/mediatheque Technical coordination: Writting and design: Terre-Écos ADEME For ADEME Cover picture: Vivescia 20, avenue du Grésillé - Agricultural and Illustrations : Gana Castagnon BP 90406 49004 Angers forestry service: Printed by: Cedex 01 Thomas Eglin, agronomy and Pure impression certificated PEFC, Registration of copyright: environmental engineer Iso 14001, Imprim’vert, Print ©ADEME Editions, November 2015 environnement ISBN : 979-10-297-0209-9

Any complete or partial representation or reproduction made without the consent of the author or his legal successors is illicit, according to the Code of intellectual property (Art L 122-4) and constitutes an imitation repressed by the penal code. The only authorisations are (Art L 122-5) copies or reproductions strictly reserved for private use of the copyist, and not intended for a collective use, as well as analyses and short quotations justified by the critical, educational or informational character of the work into which it is incorporated, only if, however, the articles L 122-10 and L 122-12, relative to the reproduction by reprography, of the same code, are respected.

Soil and carbon l 3 Issues Soils, a carbon pool essential for the climate In the form of organic matter, soils store two to three times more carbon than the

atmosphere. Therefore their use creates fluxes in CO2 and has consequences on climate change. Today, the challenge is to limit carbon losses linked to changes in land use and to increase carbon stocks by promoting suitable agricultural and forestry practices.

arbon dioxide (CO2) is equivalent of two to four years’ the main greenhouse carbon emissions. In France, 3 4 per 1,000 (GHG) linked to to 4 billion tonnes of carbon are A ‘4 per 1,000’ annual human activities. At stored in the first 30cm of soil, increase of organic matter in soil would be enough to Cthe global scale, nearly 35 billion which is three times more carbon compensate for the global tonnes of CO were emitted in than is present in forestry woods. 2 emissions of greenhouse 2013 through the consumption The levels of carbon stocks are (see page 27) of fuels such as oil, gas highly variable, depending on land and coal, and through cement use, soil type and climate. The storage, integrating changes in production. Terrestrial ecosys- trend shows a general reduction in soil carbon stocks, has become tems mitigate these emissions organic matter in agricultural soils, compulsory for European Union by capturing more than a third though there are large regional Member States. From 2013, this through . and territorial differences. has included variations linked to The evolution of carbon stocks forestry practices and, from 2021, PRESERVING STOCKS in French soils remains very will include those linked to the OF ORGANIC MATTER uncertain because of the many management of cropland and Organic matter in the soil is the mechanisms involved and the pastures. This decision is evidence largest reservoir of organic carbon, difficulty of measuring them: of the first step towards the future even greater than plant biomass. the extension of forest areas, integration of land use issues in Worldwide, the first metre of soil development of urban areas, European Union commitments to contains between 1,500 and conversion of grassland into reducing GHG emissions. Within 2,400 billion tonnes of organic cultivated areas and changes carbon markets, voluntary carbon carbon. Losses of these soils and in agricultural practices. And to offsetting schemes represent a the organic matter they contain this we can add climate change, way of valuing carbon storage throws into question their role a phenomenon which encourages in soils. Currently, at the inter- as a and increases plant production and boosts the national scale, the number of emissions. A reduction of only 5% degradation of organic matter. such initiatives and reductions in in carbon stocks represents the GHG emissions are very limited TAKING CARBON because of the diverse nature of FLUXES INTO ACCOUNT emissions and uncertainties over 3 to 4 billion tonnes With the adoption of decision storage levels. More reliable and of carbon are stored in the 529/2013/EU in 2013, keeping cheaper evaluation methods are first 30cm of French soils accounts of GHG emissions and needed.

4l Soil et carbon Dessin A

Carbon stocks and fluxes at the global scale

+ Atmosphere 4 829 + 7.8 + - - 1.1 2.6 2.3

Vegetation XX Average fluxes Fossil 350 to 550 for 2000 - 2009, carbon Ocean Soils in billion tonnes 1001 to 1940 40 000 per year 1500 to 2400 G. Castagnon XX Stocks for 2011, estimated in billion tonnes Fossil carbon • Emissions linked to land use change Carbon dissolution in the emissions and deforestation sea and by • Carbon assimilation by plants and soils marine organisms source IPCC 2013

The atmosphere contains 829 billion tonnes of carbon, among which 240 result from human activities, starting from the year 1750. The most important annual flux is linked to industrial and urban areas with 7.8 billion tonnes, to which is added the flux linked to land use change and deforestation, up to 1.1 billion tonnes. These emissions are partially compensated by carbon assimilation through photosynthesis, as well as carbon dissolution in the oceans (2.6 and 2.3 billion tonnes respectively). Some 4 billion tonnes of carbon are added in the atmosphere every year. Dessin C Dessin C Variations in organic carbon stocks depending on land use in France Urban areas Vineyards Orchards and Grasslands Forest Urban areas Vineyards Orchardsfarmlands and Grasslands Forest farmlands

Variable 35 tC/ha 50 tC/ha Variable 35˜ tC/ha 50˜ tC/ha 80 tC/ha 80 tC/ha ˜ ˜ ˜ 80˜ tC/ha ˜ ˜80 tC/ha G. Castagnon

source GIS sol XX Estimate of carbon stored within the 30 first centimetres of soil XX Estimate of carbon stored within the 30 first centimetres of soil Organic matter stocks in forests, grasslands and low vegetation growing in highlands are large, whereas stocks are quite low in vineyards, farmlands and Mediterranean zones. Quantifying stocks is difficult in urban areas; nevertheless, a significant amount of carbon could be stored under green spaces. Carbon stored in forest litter is not taken into account.

Soil and carbon l 5 Issues Continuously providing soil with organic matter

Soil organic matter can be defined as ‘everything that is alive or was alive in the ground’. Organic matter undergoes a degradation which leads to mineralisation. Carbon contained in organic matter is largely released into the atmosphere in the form of a gas. So, in order to maintain carbon stocks, there must be compensation for these losses. Here we explain further...

rganic matter enters released into the atmosphere*. and tropical forests, the storage the soil in a ‘fresh’ To a lesser extent, losses of of organic matter in the soil form: plants (fallen organic matter are also due to happens with the same rapidity leaves, crop resi- leaching of dissolved organic as its degradation. In agro- Odues, root exudates etc.), micro- matter, water and wind erosion, ecosystems this balance can organisms or dead animals. A and fire. be disturbed by many factors, large part is quickly decomposed: which can favour the accumu- in a few months, organic matter THE INFLUENCE OF lation of organic material or, on is mineralised by decomposers CLIMATE AND SOIL the contrary, its mineralisation. such as fungi and bacteria, CHARACTERISTICS Rainfall and temperature play a and transformed into carbon In the soils of some large ecosys- major role. For example, low or

dioxide (CO2) which is quickly tems, such as African savannas high humidity levels can hinder

Dessin How is B organic matter formed and degraded?

Organic matter inputs Organic matter losses Agricultural Ploughing Water Fire spreading and harvest erosion CH Crop residues, CO 4 plant covers 2

Endogenous Exogenous inputs inputs Microbial OM OM Root inputs OM activity

Leaching G. Castagnon

Apart from root inputs, the major source of organic matter inputs is from the surface. On the other hand, organic matter degradation is mainly an underground mechanism, ensured via microbial activity. Possibilities for action can involve both increasing inputs and reducing losses.

6l Soil et carbon A.D.

Roots contribute a lot to carbon storage in soil the activity of decomposers in soils which naturally accumulate Expert opinion more organic matter than others. Conversely, a 10°C increase Éric Blanchart in temperature can double Research director or even triple microbiological French Institute of activity. Climate change, which Research for Development currently stimulates plant pro- ductivity (temperature and CO 2 Structure and nature of soils influence organic concentration in the atmosphere) matter stability and mineralisation of organic “While the major share of organic matter is quickly mineralised, matter, has an impact on car- a more modest quantity can undergo three mechanisms which bon storage which is difficult to can help it stabilise and resist mineralisation. First possibility, assess. Finally, the physical and a chemical transformation: some microbes can transform chemical characteristics of soil organic matter into complex carbon molecules, difficult to reduce mineralisation through degrade chemically. The second option consists in integrating organic matter in aggregates, in order to create a physical their ability to ‘protect’ organic barrier against ’ action. Third possibility: if soils matter (see box). are rich in clays and carbonates, these elements can react with organic matter, creating a physico-chemical protection against FARMERS: MANAGERS mineralisation. Finally, even if organic matter can be protected OF ORGANIC MATTER and remain stable for a long time – up to several thousand When harvesting, farmers remove years – it always ends up mineralised .” large amounts of plant mate- rial. This means the quantity of organic matter returned to fore, mineralisation. Given the matter and adapting losses to the soil is limited. Furthermore, important role of organic matter a minimum. practices such as ploughing and its positive influence on *Some organisms (autotrophic, anaerobic) can aerate the soil and encourage the environment, the idea is to consume CO2 before it is released in the atmosphere. However, they are very few of them and so this microbial activity and, there- maintain high inputs of organic mechanism is considered as minor.

Soil and carbon l 7 Issues Organic matter: providing environmental services

Organic matter in soils is essential for the proper functioning and sustainability of agricultural and forest ecosystems. Organic matter ensures soil stability, carbon storage, , biodiversity etc. Some of these services depend on the quantity of organic matter contained in the soil while others depend on the mineralisation of organic matter.

rganic matter provides multiple Bio-indicators to evaluate organic matter dynamics environmental ser- Bacteria and fungi degrade organic matter, nematodes vices. First of all, regulate populations and earthworms Oorganic matter is a food source structure soils...The ADEME ‘Soil quality bio-indicators’ for organisms living in the soil, programme aims to provide a better understanding of the role microorganisms and fauna. A of soil-living organisms, in order to supply public and private soil with a high organic matter stakeholders with tools for monitoring and characterising content encourages the pres- soil quality. The monitoring of many variables linked to soil ence of these animals and plants, ecosystems, in different agro-climatic conditions, has made it possible to evaluate the impact of managing soil organic which are both numerous and matter on biodiversity. The abundance of fungi and microbial varied, and therefore enhances groups and the diversity of nematodes have been identified biodiversity. as early indicators of changes in a soil’s organic quality.

MINERALISATION, POSITIVE FOR PLANT ... THOUGH effect. Nitrate and phosphate NUTRITION... COMPENSATION IS ions released represent profi- Organisms living in the soil feed NEEDED TO MAINTAIN table nutrients for plants but, on organic matter, and hence CARBON STOCKS AND if not assimilated, they can be contribute to its decomposition LIMIT CONTAMINANT transferred to water flows. Mine- and mineralisation. Yet, organic TRANSFERS ralisation can also free organic matter acts as a sponge in the The mineralisation of organic and metallic contaminants which soil: it adsorbs and contains matter has other effects. First of were trapped in organic matter. various elements which are all, it produces simple molecules Therefore it is important that released once mineralised. In such as greenhouse gases stocks of organic matter are pro-

agricultural and forest ecosys- (CO2, N2O or CH4, depending gressively replenished, through tems, plants benefit from the on the degradation conditions), plants or exogenous inputs which cations and elements which are mainly released into comply with regulations. If these released as they contribute to the atmosphere* and therefore stocks are maintained, the ser- their nutrition. contribute to the greenhouse vices provided by mineralisation

8l Soil et carbon Expert opinion Organic matter: providing Claire Chenu Teacher-researcher and FAO soil ambassador environmental services AgroParisTech

Multifunctional Both the presence and degradation of organic matter are very important. It is a real ‘turntable’ for the cycles of major elements (carbon, and phosphorus) and pollutants in soil © CLUZEAU Daniel/INRA © CLUZEAU ecosystems. It acts as a A soil profile made of soil clods and aggregates is a complex living filter for the environment system, providing habitat for soil microflora and fauna. by storing natural contaminants, not only organic but metallic and can be ensured, carbon stocks environment. Indeed, crop roots synthetic. When degraded, remain constant and contaminant benefit from aerated soils and the organic matter benefits transfers can be limited. infiltration of water is enhanced, the environment in a avoiding problems such as runoff different way, by providing PROVIDING and erosion. a nutrient supply for STRUCTURE FOR SOIL plants and enhancing soil Dessin E * Very few microorganisms are able to consume biodiversity. Finally, the maintenance of a these gases in the soil. certain quantity of organic matter is essential to soil structure, as well as its stability when faced with rainfall. In effect, organic Climate Carbon storage matter acts like ‘glue’ in the soil. It aggregates mineral particles and G. Castagnon also provides a food supply for Water flow organisms (microorganisms, and quality earthworms) whose acti- Ca2+ Retention of water 2+ Soil organic Mg + vities are also beneficial and pollutants K for soil structure. Therefore, matter organic matter contributes Chemical directly and indirectly to soil Soil fertility structure, which profits biological and soil both agriculture and the activity structure

Soil and carbon l 9 Points of view Carbon storage in soils: rising awareness

Research Dominique Arrouays, Research engineer and and public scientific coordinator of the policy are Global Soil Map Programme, joining forces Infosol Unit of the National to boost Institute for Agricultural carbon in Research (INRA), Orléans. French soils and therefore better combat climate change.

Joseph Lunet, project leader responsible for agriculture he general public may not and forest in the Ministry of yet be fully aware of the Sustainable Development importance of soils as a (Energy and Climate Head carbon pool and a tool Office, Greenhouse Mitigation Tfor mitigating climate change. Department). However, the business com- munity and the political sector in improving knowledge about and past land use, climate, clay have started to show an interest. the mechanisms and amounts content, soil depth and agricul- “In the agricultural and forestry of carbon involved. He explains: tural and forestry practices as sectors, awareness is rising,” “The French state supports public the main sources of variations explains Dominique Arrouays, research programmes which aim in carbon levels in French soils. an INRA researcher specialising to improve our knowledge, under “The potential for increasing in soil. He adds: “It probably isn’t the supervision of GIS Sol(1). stocks is not necessarily found in so true for actors in the parks Working on a better knowledge the most carbon-weak areas,” he sector and those working in of carbon fluxes in farmland and explains. “It might be more useful regional planning.” At the Ministry forest soils is essential.” to preserve or increase already of Sustainable Development, high stocks, rather than try and Joseph Lunet confirms that MAINTAINING OR create new ones in areas where present policies do consider ENRICHING ALREADY the potential for stabilisation is the major role played by soils. LARGE STOCKS low. Furthermore, region-specific According to him, public autho- For the moment, Dominique actions exist, depending on the rities are especially prominent Arrouays considers present business sector.”

10l Soil et carbon Map of carbon stocks in French soils Thanks to the Soil Quality Measurement Network (known by its French initials RMQS – www.gissol.fr), soil carbon stocks have been mapped. They seem greater in highlands and livestock areas. The network does not provide a value for carbon stocks in urban areas (shown in white on the map). However, the inventory of national greenhouse gas emissions suggests that urban areas could contain half the stocks of grassland areas. It takes into account, among others,

gardens and urban

parks. France would like to see the land-use sector “ “ included in future international climate

agreements.

Organic carbon stock (Kg/m²) More than 13 and ecologically important Between 10 and 13 Between 7.5 and 10 areas, ban the destruction of Between 4 .5 and 7.5 Less than 4.5 some natural meadows, limit Urban area clearance of wooded areas and tackle urban sprawl etc. The representative of the Ministry of Sustainable Development adds

source : Meersmans et al. 2012 that the issue of carbon and soil is not currently at the heart of climate-related policies, “because GROWING soil carbon is poorly taken into

IMPORTANCE OF In the agricultural account within the framework of

INCENTIVE MEASURES and forestry sectors, the Kyoto Protocol”. According According to Joseph Lunet, “awareness is rising. It to him, France would like to support measures which aim needs to be developed “ see that the land-use sector is to preserve or increase carbon in the parks sector and “included in future international

stocks in agricultural soils are regional planning. climate framework agreements, increasingly important, especially post 2020”. That way, policies with the new 2014-2020 CAP could take greater account of (Common Agriculture Policy), and incentive measures to protect or through France’s ‘Loi d’avenir’ increase soil carbon stocks. legislation for agriculture and forests. Indeed, these policies (1) Group of scientific interest including INRA, support incentives for the pres- ADEME, IGN, IRD and the Ministries of Agriculture ervation of permanent grassland and Environment.

Soil and carbon l 11 Dessin F

Impacts and levers for action A => F : 190 F=> Natural lands (N) : 815 N=>F : 584 N => A : 395 Farmland: A=>N : 238 Changes in land use: the need 28 000 thousand hectares to preserve carbon-rich soils Urban land: The reconstruction of organic carbon stock in the 5100 thousand hectares soil takes several decades. This means we should focus on protecting those areas which contain the 190 highest stocks, and on controlling urbanisation. 524 815 urning grassland into land, permanent grassland has cropland leads to a deple- seen the biggest impact, with 395 238 tion in soil carbon, while a loss of 1.6Mha, mostly for 584 afforestation of cropland conversion to crop cultivation. Tincreases carbon storage. Accor- ding to the Ministry of Agriculture’s CONTROLLING LAND Natural land and forests: annual agricultural statistics, USE 21800 thousand hectares the main land-use changes in Although afforestation increases France between 1990 and 2010 carbon stocks, urbanisation and, included a 0.6 million hectare in particular, soil sealing leads to (Mha) increase in afforested a loss of organic matter and soil land, but also an increase in functions which are very difficult,

© A.D. urbanised land of 1.4Mha. These if not impossible, to reverse. land-use changes have been to In all cases, in order to preserve Ploughing up grasslands for crop the detriment of farmland, cau- French soil carbon stocks and cultivation causes carbon losses. sing a net loss of 1.3Mha over maintain ecosystems which act The Common Agricultural Policy 20 years, and a 0.7Mha loss of as carbon sinks, natural environ- encourages farmers to preserve grasslands. natural land. Within agricultural ments should be protected and

Carbon stock evolution, depending on land-use change

40 During the first twenty years which follow a change in land-use, carbon More than 400,000ha of is lost twice as fast as it is stored. 20 grassland have been ploughed Only after several decades or even in France since 2000, and more than a century can carbon 1.6Mha since 1990. 0 storage compensate carbon losses. (source: Agricultural Statistics). -20 In France, 70,000ha far- (tC/ha) Carbon storage Source: Arrouays and al. 2002 cropland -> forest mland hectares have been -40 cropland -> grassland lost between 2006 and 2014, 0 20 40 60 80 100 120 forest -> cropland according to Teruti-Lucas. Application period (years) grassland -> cropland

12l Soil et carbon Dessin F

A => F : 190 F=> Natural lands (N) : 815 N=>F : 584 Changes of land-useN => A : 395 Farmland: between 2006 andA=>N : 2014,238 in France 28 000 thousand hectares Land-use changes create carbon fluxes. The current resolution of spatial monitoring and lack of knowledge concerning urban land limits the precision of measurements. Urban land: 5100 thousand hectares 190 524

G. Castagnon 815 395 238 584

Natural land and forests: 21800 thousand hectares

F luxes in thousands Source: Teruti-Lucas survey of hectares from 2006 to 2014, including 2014 surfaces.

livestock systems should preserve grasslands. Regarding agriculture, Antonio Bispo agro-environmental measures Expert Soil and environment deter the ploughing of grassland opinion engineer at ADEME after five years. The French Safer(1) group can also intervene to pre-empt lands threatened by Integrating carbon stocks in GHG environmental urbanisation. Other regulatory assessments in land-use policies levers are foreseen in the codes “Any change in land use, whether it is for non-food crops or for dealing with urbanisation, rural urbanisation, can have consequences, not only in France but areas and the environment, also in developing countries. So, deforestation may intensify in and within the framework of the order to maintain the offer of raw materials on world markets. ALUR law(2). They involve various Within the framework of a working group launched in 2010, the impact of French policies promoting bio-fuels on farmland mechanisms, such as protection use and CO emissions has been evaluated. This research is zoning, pre-emption and norms 2 now being extended and is integrating different scenarios on urban densification. and drivers in land-use changes, such as urbanisation and agricultural objectives, both at a national scale and worldwide. Competition for different land uses is a major issue for public (1) Real estate development and rural establishment policies.” companies (2) Law for access to housing and renewed urban planning.

Soil and carbon l 13 Impacts and levers for action Forest soils: rationalising the increase in harvested wood

The demand for and disruption of forest soils is lower than for farmland, and they evolve slowly. Nevertheless, their fertility is limited and very dependent on natural flows of elements and organic matter. An increase in wood demand for energy purposes needs to be accompanied by measures seeking to protect them. © A.D.

The medium and long-term effects of wood harvesting intensification on carbon stocks are not well known. The impacts of different practices strongly depend on soil characteristics.

n chemical terms, forest soils much carbon stored in the soil long-term evolutions, especially are generally the poorest within as there is in the trees. under the influence of changes a territory, or those whose in forestry practices. physical characteristics are the SUSTAINABLE In the future, the foreseeable Imost unfavourable to agriculture. FORESTRY PRACTICES increase in wood demand - for Unlike agricultural soils, they Carbon stocks evolve more energy or material needs - will undergo no or very little altera- slowly in forest soils than in encourage the intensification of tion due to human activity. As a agricultural soils. Usually, they forest harvesting. The impact of result, organic matter is highly are assumed to be stable, but this intensification on stocks is accumulated in the litter and very little monitoring has been uncertain; it could lead to oppo- surface layers of soil. In temperate conducted to make it possible sing effects on litter production forests, there is approximately as to know their true medium and and the integration of harvest

14l Soil et carbon waste in the soil. Nevertheless, a for ADEME. greater harvest of forest residuals, Laurent which includes young trees and Expert Augusto branches remaining on land opinion INRA researcher after harvesting and pruning of trees, for energy needs, directly decreases soil intakes of carbon. Indicators to protect soil fertility The ADEME guide* on ‘The “The challenge for research consists in finding logistical sustainable harvesting of forest levers in order to mobilise underexploited woodland, but residuals’ recommends that not also in finding good compromises to manage forests which all of the above-ground biomass are increasingly in demand. The latter have to preserve their should be taken: a portion of the various functions, such as wood production, biodiversity residuals should be left on the reservoirs and carbon storage. In this context, maintaining ground at each harvest, and resi- organic matter stocks in forest soils is essential, because unlike other countries, French forests receive practically no duals should be collected once, inputs to contribute to soil fertility. Yet, half of the forests are maybe twice, in the stand’s life. former farmlands reforested in the middle of the 19th century, These recommendations were because they were too poor or difficult to cultivate. In order made in order to preserve the to preserve this capital, the challenge consists in finding the mineral chemical fertility of forest right balance between exported wood and the wood left on soils and reduce soil compaction, the ground. Today, research projects are seeking to develop but are also valuable in preserving indicators so forest managers can improve their harvesting carbon stocks. practices.” Gestion* The Forêts guide will be updated on the basis of the collective expertise RESOBIO coordinated in 2013 by GIP ECOFOR

Elements in the GHG balance in the wood sector Harvesting larger quantities of forest wood could limit increases in carbon stocks in the soil and trees. For a complete evaluation of the GHG balance in the wood

G. Castagnon sector, we need to take into account carbon storage in wood products (construction and furniture) as well as 50 year 200 year substitutions of other materials and fossil fuels. forest forest rotation rotation Construction and furniture • Replaces fossil materials • Stores carbon Energy • Replaces fossil energies

Soil and carbon l 15 Impacts and levers for action Agricultural soils: acting on organic matter inputs and losses

To boost carbon levels in agricultural soils, two specific actions have been identified: favouring practices which increase stocks of organic matter and limiting those which increase losses of organic matter.

ccording to INRA esti- of intermediate crops in crop mates in 2002 and rotations, grassing between rows 2013, the maximum in vineyards and orchards, and potential of additional extending the lives of temporary Acarbon storage in agricultural grasslands. soils should reach 1 to 3 million The planting of hedges and grass tonnes a year over 20 years. and flower strips enriches the This storage could compensate soil in organic matter alongside a significant proportion - some their role as biodiversity reser- 3 to 4% - of France’s annual voirs, ecological corridors and © A.D. greenhouse gas emissions, but buffer zones between crops In order to return higher amounts would require a very pro-active and water courses. With the of organic matter to the soil, it approach. introduction of rows of trees in is necessary to favour soil cover The practices which should fields and pastures, agroforestry by including intermediate crops be implemented involve either techniques lead to an increase of in the rotation and grassing increasing inputs of organic the carbon stocks in soils as well between the rows in vineyards matter or reducing losses. as in wood. In low productivity and orchards. grasslands (grazing land, high SUPPLYING MORE mountain pastures and moor- ORGANIC MATTER land), moderate intensification In France, less than 1% of The first action identified to practices can be implemented. cultivated land is directly increase soil carbon stocks is For crops and grasslands which sown. to increase plant production have already been intensified, 4.6Mha is cropped using and return more organic matter the concern is not to increase simplified cultural techniques, to the soil. To achieve this, it is inputs but to better preserve crop a third of the cultivated area. necessary to promote the use of residues. Finally, the application (Source: Arvalis Institut du Végétal). soil cover through the inclusion of organic matter from urban

16l Soil et carbon sources or of manure could be sowing and more or less deep preserve part of the possible gain an interesting solution at the interventions. Their impact on in carbon stocks and, above all, local scale, provided low-carbon carbon stocks has often been save on fuel. soils are prioritised and it meets overestimated. existing regulations. Based on the monitoring of Expert experiments conducted by the SLOWING CARBON international scientific community, opinion LOSSES only direct sowing provides an Hedges and soil cover also effect average increase over plou- Jérôme Labreuche carbon stocks, by reducing runoff ghing (0.15 tonnes of carbon Agro-equipment centre and losses due to erosion. storage per year). This result manager at Arvalis- Plant Putting an end to ploughing is highly variable depending Institute would lead to an increase in on the situation. Moreover, field soil-carbon levels as colder trials led by Arvalis over 40 and wetter surface conditions years on the Boigneville site and better physical protection in Essonne (south of Paris), in the aggregate slows down show that after a 2t/ha annual Taking better the mineralisation of organic organic carbon storage over 24 account of matter. According to the Arvalis years, direct sowing does not practices which plant institute, 34.4% of France’s differ from ploughing after 40 enhance organic cultivated land is currently crop- years. Furthermore, ploughing matter inputs ped using simplified cultural is sometimes necessary for The implementation of techniques (no-till or low-till), agronomic reasons (see box). intermediate nitrate- trap crops (INTCs) during mainly autumn crops. Low- According to INRA, occasional long interculture periods till techniques include direct ploughing every five years would has been encouraged by regulatory obligations. This farming practice When ploughing is improves soil humic justified balance, especially since carbon storage According to the Arvalis by INTCs has recently plant institute, ploughing been reappraised. is most often conducted There is also a trend for for spring crops and on keeping these crops for soils low in clay content. a longer time-period, It provides security for and planting them in spring crops, as ploughing areas where it is not encourages crop emergence necessarily compulsory. and improves soil structure Another evolution in in situations where there practices has been is a significant risk of soil spotted: in cereal compaction (late harvesting or loamy soils). It is also the case production areas, some that for easy-to-plough soils this practice is not often called into farmers do not hesitate question. In a context where weed control is increasingly complex, to add organic inputs to ploughing is recommended, especially where there is strong the soil. pressure from grass weeds.

Soil and carbon l 17 Impacts and levers for action Agricultural practices according to their cost and efficacy

In 2013, INRA analysed the potential of agricultural practices for mitigating French GHG emissions. Agroforestry, no-till, extending the life of temporary grasslands and maintaining permanent soil cover appear to be the most effective levers for stimulating carbon storage. Here we present the lessons learned.

en different actions have at less than €25 per tonne of matter: increasing the life of

been identified by INRA CO2-equivalent avoided. temporary grasslands (1.44Mt

for limiting agricultural CO2-equivalent per year) and emissions of three major UNDERSTANDING ALL extending the grazing period. greenhouse gases (CO , N O Extending grazing periods also T 2 2 THE BENEFITS

and CH4) over the next 15 years. Other moderate-cost measures influences other GHGs because These measures have to be stimulate the storage of organic part of the manure usually emitted pragmatic and avoid yield losses beyond 10%. Added together, they Estimation of impacts of agricultural practices could lead to a 32 million tonne on carbon storage

CO2-equivalent reduction per year by 2030. These measures also include economic factors. Those which aim at reducing Permanent Hedges and CO2 emissions together with Agroforestry increasing farmers’ revenues act plant cover plant strips High Cost High Moderate mainly on economies in the use Increase in plant productivity > Increase in plant productivity > of fossil fuels and carbon storage Increase in organic matter physical protection > in soils and biomass. Mechanisms involved in C Reduced carbon losses due to leaching and erosion > Reduced carbon losses due to leaching and erosion > Regarding storage in the soil, the most effective miti- gation measures are occasional Between 0,1 Hedges Between 0,1 and 1,35, ploughing (3.77Mt CO2-equivalent Potential units of and 0,35 • In grasslands: 0,14 including per year) and agroforestry (1.53Mt carbon storage In croplands: 0,25 approximately 2/3 in CO -equivalent per year). However, over 20 years in • Plant strips the soil 2 0,5±0,3 the long-term impact of occasional the INRA study, in tC/ha/year. ploughing needs to be clarified (Pellerin et al. 2013 ; (see p.17). The cost-efficiency of Arrouays et al. 2002) these measures remains modest Note :

• A tonne of carbon stored is the equivalent of around 3.66 tonnes of CO2 captured. • Agricultural land in France covers around 28.2Mha. 18l Soil et carbon Agricultural practices Expert Sylvain Pellerin Coordinator of the INRA study: ‘Ten measures opinion to reduce GHG emissions through agricultural according to their cost practices’ and efficacy “For the first time, we have measured and quantified GHG emissions mitigation potential, and the related costs. Carbon storage is favoured by moderate-cost measures, such as no-till or agroforestry. In order to improve the carbon-storage dimension of these practices, inventory methods have to progress. Today, only land-use change impacts are measured.”

in the barn, and the emissions environmental aspects, such biomass represent 30% of the

of N2O and CH4 associated as conserving the quality of potential mitigation of GHG with it, will be reduced. The water, soils and biodiversity, of emissions, when including

planting of hedges, intermediate which the economic impact has their effects on CH4 and N2O crops, permanent grassing in not been taken into account in emissions, and the substitution vineyards and orchards and this study. of fossil fuels. Beyond the date introducing flower or plant set in this study - 2030 - car-

strips (2.77Mt CO2-equivalent CARBON STOCKS bon stocks will reach a ceiling

per year) have a higher cost, CAPPED IN THE and net CO2 fixation will end. mainly because of the working MEDIUM-TERM However, the other effects of time required. Nevertheless, Overall, the levers relating to mitigation, such as savings in these measures benefit other carbon storage in soil and fuel, will continue.

Grassing in Grassland No-till Spreading of Return of vineyards management techniques effluents and crop residues

High compost and orchards Moderate Moderate Moderate Moderate Increase in plant productivity > Increase in plant productivity > Increased return of organic matter to the soil Increase in organic matter physical protection > Reduced carbon losses due to leaching and erosion > Reduced carbon losses due to leaching and erosion >

Lower mineralisation if the ratio C/N is high

• For permanent soil • Increase in temporary • Transition to direct Between 10 and 50% 0,15 for 7 tonnes covers in orchards: grasslands’ lifetime sowing, 0,15 of the carbon input, of straw 0,5±0,3 (< 5 ans): 0,15 • Transition to ploughing according to type of • For permanent soil • Moderate every five years: 0,10 input. covers in vineyards: intensification • Shallow tillage: no 0,3±0,2 of poor permanent additional C storage • For temporary soil grasslands: 0,4 covers in vineyards: 0,16

Soil and carbon l 19 Points of view Reconstructing carbon stocks Many benefits to highlight

Practices which favour the storage of organic matter or which preserve carbon already existing in the soil are better perceived in the field if they combine several environmental benefits. Different tools and levers are available to make their implementation easier. Here we explain.

raising programmes based on the multiple environmental benefits.” Sandrine Leménager, project Sandrine Leménager, leader at the soil division at the project leader on soil agriculture, food and territorial subjects at the head policies department (known office of Agriculture, by its French initials DGPAAT) Food and Territorial of the Ministry of Agriculture, Policies (DGPAAT) identifies new opportunities to at the Ministry of better take into account issues Agriculture. relating to soil carbon and cli- mate. The timetable provides Jean-Luc Fort, head of the evidence: “2015 is a pivotal year,” armers are aware of the agronomy and environment she says. “France is hosting importance of carbon sto- service at the Poitou- the 21st climate conference, rage, particularly in regard Charentes Chamber of Paris Climat 2015 (Cop21). It to its benefits for biological Agriculture and coordinator is also the International Year Factivity and overall soil fertility. of the ‘Sols et Territoires’ of Soils. The 2014-2020 CAP Combined Technology Yet the role of organic matter in (Common Agricultural Policy) Network. in environmental assessments is strongly prioritises measures poorly taken into account. “The which ensure greenhouse gas time required for reconstructing Agriculture, and coordinator of mitigation through carbon storage carbon stocks is so long that the Sols et Territoires (soil and in soils, such as the preservation this issue isn’t enough to trigger land) Combined Technology of pasture, soil cover, areas of corrective measures in agricul- Network. ecological interest…Finally, the tural practices,” says Jean-Luc “On the other hand, technical fight against the urbanisation Fort, manager of the agronomy bodies, agricultural advisers and of farmland and forest helps to and environment service at the cooperatives are involved in plenty protect the ecosystem services Poitou-Charentes Chamber of of development and awareness- provided by soil carbon storage.”

20l Soil et carbon Context Measures encouraging carbon storage

Measures Levers Ongoing discussions about organic residues and current policy Organic matter inputs promoting farm-sourced organic matter. Intermediate crops, Nitrates Directive and implementation legislation. Grass or flower strips CAP- greening: zones of ecological interest Using only the

Grassing in vineyards CAP, agro-environmental measures carbon storage angle is and orchards

“not enough to encourage CAP, agro-environmental measures Hedges, Agroforestry Art. 23 of 2014-2020 rural development regulation favourable farming“ CAP - greening: zones of ecological interest systems. We need a CAP - greening: no ploughing of permanent pasture classed

multifunctional point of Preservation of as sensitive, and for other areas if Member State wishes. The permanent pasture diminution rate of permanent pasture must not exceed 5% view. nationally.

PRIORITISING INCENTIVE they are based on the environ- aspects. Innovative crop mana- MEASURES mental benefits and economic gement techniques combining According to Sandrine Leména- compensations obtained, and several environmental goals are ger, approaching carbon issues not only on the administrative very welcome since they also through agricultural practices management of a problem. include agricultural and eco- which favour its storage is the “We need to turn this around, nomic interests. In our region, entry point. The practices identi- to value the agricultural and lucerne (alfalfa) is a perfect fied concern soil cover, notably economic benefits of a better example of positive synergy: we intermediate crops, flower or consideration of environmental use lucerne as a low-input crop grass strips, inputs of organic which benefits the rotation with, matter and the development in parallel, the maintenance of

of agroforestry, but also hedge livestock which feed on it and Measures which maintenance and afforestation. add value to the crop.”

encourage carbon She insists: “There are tools to This synergy can even go beyond encourage the implementation of storage meet the goals the farming sector. Among

“ “ each measure, particularly within of the French agro- the selected measures which the CAP. Some are incentives, ecological project. increase organic matter, San- others are statutory, but there is a drine Leménager favours the clear tendency to better take into spreading of organic matter account soil and carbon issues inputs, “on the condition that within agricultural practices.” their safety and agronomic value For Jean-Luc Fort, the agro- have been demonstrated. The environmental measures included Ministries of Agriculture and in the second pillar of the CAP of Sustainable Development (Common Agricultural Policy) are working to this end,” she are relevant levers, because adds.

Soil and carbon l 21 Evaluation Measuring changes at the field scale

At the field scale, the influence of the actions implemented on soil carbon stocks can be assessed through direct measurements and estimated with the help of models. The latter can help agricultural advisers in changing agricultural practices. Below is an overview of the tools and norms available.

he impact of field manage- Estimation of Example of norm Objective ment on soil carbon stocks Isolate particular organic can be quantified using material (plant residues in Organic matter dynamics NF X31-516, 2007 direct measurements, course of decomposition) and Tbefore and after the implemen- organo-mineral complexes Soil microbial biomass NF EN 14240-1 et -2, 2011 tation of new practices. Estimate the microbial activity NF EN 16072, 2011 of organic matter degradation Certain enzyme activities NF EN 23753-1 et -2, 2011 DIRECT Earthworms NF EN 23611-1, 2011 MEASUREMENTS TO Mites and springtails NF EN 23611-2, 2011 Value the number and EVALUATE RESULTS diversity of invertebrates Enchytraeid worms NF EN 23611-3, 2011 involved in organic matter Direct measurement methods dynamics (e.g. earthworms, require particular caution (see Nematodes NF EN 23611-4, 2011 nematodes) box ‘Expert opinion’). We have to Total macro-fauna PR NF ISO 23611-5, 2010

Expert Annie Duparque Head of agronomy at Agro-Transfert Ressources opinion and Territories, and partner in the RMT Sols et Territoires (soil and land combined technology network).

Carbon dynamics: three key points to bear in mind “In order to assess carbon dynamics, we need a relevant sampling procedure. Different measures have to be made on the same soil amount, and bias must be avoided due to the spatial heterogeneity of organic matter content in farm fields. “We need to be careful on three different points: recording the samples’ locations with a GPS, and returning to the exact same place for further measurements five to seven years later; to rationalise the sample depth according to the depth of tillage, and keeping it unchanged from one measurement to another; if possible, to determine the soil bulk density through the depth of the sample. “Carbon content analysis of preliminarily air-dried samples is performed by a laboratory. Then, the organic carbon stock (t/ha) can be calculated by multiplying carbon content with the mass of soil, estimated via depth sampling and bulk density.”

22l Soil and carbon The evaluation of carbon dynamics in cultivated soils requires the following

Agriculture Chamber of Oise (60) Chamber of Agriculture of a precise protocol. wait between five and 10 years USING MODELLING TO practices (crop rotation patterns, before the impacts of changes GUIDE AGRICULTURAL residue management, organic in agricultural practices can be PRACTICES inputs, intermediate crops, tillage, observed. Analytical methods Thanks to models such as AMG, irrigation) and on soil and climate can be used for an early esti- established in France by INRA in characteristics. Specific models are mation of changes in organic Laon (02), we can also simulate also available for France’s overseas matter (see chart opposite). In changes in agricultural practices. territories, such as the Web Mor- order to predict the effects of Agro-Transfert-RT, INRA and part- Gwanik application developed for inputs of exogenous organic ners in the agricultural sector have Guadeloupe, which are designed matter (liquid manure, fertiliser, developed a decision support sys- to include the specificities of the compost) on carbon stocks, bio- tem integrating this model, called climate, farming systems and soils degradability indicators based on Simeos-AMG. Designed for use found in the country’s outermost the biochemical composition of in agricultural advisory services, it regions. Used within the framework inputs have been developed and simulates and displays the expected of energy performance plans, standardised. An example is the changes in soil organic carbon ADEME’s tool Dia’ Terre® can organic matter stability indicator stocks in the long-term (20, 30, 50 include soils in farm greenhouse (NF XPU 44-162, 2009). years etc.), depending on agricultural gas assessments.

Simeos-AMG, a simulation tool for agricultural advice use at different scales Vegetable production, silt soils (rotation: potatoes/wheat/peas (canning)/beetroot/wheat/carrot)

CURRENT SYSTEM A SCENARIO Organic matter content evolution in the tilled layer of the soil • Ploughing: 2 years out of 3 (Reduced C losses) • Ploughing depth: 28cm • No ploughing 9,25 1,85 • Green fertilisers: (1 year out of 2) 9,00 1,80 1 year out of 3 • Reduction of ploughing depth to 22cm 8,75 1,75 B SCENARIO C SCENARIO 8,50 1,70 (Inputs of humic substances) • Input of green waste 8,25 1,65 current system

• Input of green waste compost: 8,00 a scenario 1,60 (%) OM content compost: 10t/ha over 10t/ha over 6 years b scenario

Organic C content (g/kg) C content Organic c scenario 6 years • One ploughing removed 7,75 1,55 0 6 12 18 24 30 • Green fertiliser: 1 year and reduction of depth to Years out of 2 22cm Source agro-transfert RT, Duparque et al, 2011

Soil and carbon l 23 Evaluation Measurement tools at the territorial scale

Direct measurements, national databases, modelling, etc.: evaluation tools offer the possibility of monitoring the impacts of public policies and predicting changes in soil carbon stocks.

s for fields, soil carbon MEASUREMENT RMQS is based on the moni- stocks can be moni- NETWORKS AT THE toring of 2,200 observation sites, tored at the territorial NATIONAL SCALE divided according to a 16km level thanks to direct In France, two main networks, per side grid across the whole Ameasurements and modelling. complementary in their design, territory. This network supplies Using direct measurements are managed within the framework average data and representative requires the introduction of of GIS Sol: RMQS (soil quality values of carbon stocks for the sampling networks. measurement network) and main land uses (forests, crops, BDAT (soil analysis database). permanent pasture etc.). Analyses

Expert Olivier Scheurer Lecturer at the Institut Polytechnique LaSalle opinion Beauvais, and partner in the RMT Sols et Territoires (soil and land combined technology network).

Net balance of CO2 emissions for the cultivated red Modelling offers the possibility soils in Vienne, calculated from simulated changes of estimating the effects of over 50 years. modifications to cropping systems Balance Balance at small regional agricultural levels (tC/ha/yr) (tC/ha/yr) “Within the work conducted in Sols et Territoires(1), Red soil - 86 -0.05 0.01 we showed that it was possible to apply the AMG Average depth -0.10 -0.05 model for carbon dynamics in agricultural soils, Shallow 0.07 0.13 based on a spatial inventory of ‘soils, cropping Deep -0.10 -0.03 systems, and current organic carbon content’. To Without With achieve this inventory, pre-existing databases intermediate intermediate were used: CAP data, pedological regional crops crops references (RRP) and the soil analysis database. Nevertheless, local agronomic expertise is necessary to group these data. The chart (left) shows a model application in Poitou-Charentes (Vigot, 2012): the introduction of intermediate crops limits carbon losses and even increases stocks depending

on the soil type in question.” (1) www.sols-et-territoires.org

24l Soil and carbon Measurement tools at the territorial scale A.D.

We can analyse the consequences of changes in cropping systems on carbon stocks thanks to models at the agricultural territorial level.

are also conducted to charac- extending these changes to all complete and extrapolate direct terise agronomic parameters, French farmland comes with measurements. This is the case contamination levels and soil great uncertainties linked to the for the methods developed biodiversity. Thanks to the first temporal and spatial diversity by INRA, working with Citepa sampling campaign between of the sampling and analytical (a technical centre studying 2001 and 2011, carbon stocks methods. In France, there are other atmospheric pollution), based on in mainland France and the observation networks integrating the GIS Sol database, in order French West Indies have been soil carbon measurements too. to feed national inventories for evaluated. Starting from 2015, a For example, the Renecofor GHG emissions. Other tools have new sampling campaign will be network monitors 102 forest sites been developed for use at the conducted in order to observe in mainland France. The SOERE territorial scale. The Simeos-AMG changes in stocks. All the RMQS network (observation and expe- tool made it possible for the AMG samples are conserved at INRA’s rimentation system for long-term model to be implemented at the national soil sample conservatory environmental research) brings agricultural territorial level in Loiret in Orléans. together different sites chosen to and Poitou-Charentes (see box). BDAT is a database which estimate the long-term impacts of The ABC’Terre project (Reacctif gathers the results of soil ana- climate and agricultural practices. ADEME 2012) continues this work, lyses conducted by farmers. The and will also lead to the deve- database groups around two MODEL-BASED lopment of a calculation method million samples taken since 1990. EVALUATIONS for GHG emissions balances, Thanks to the data collected, it The implementation of observa- integrating soil carbon balances has been shown that agricultural tion networks is limited due to at the agricultural territorial level. soils tended to lose approximately their cost and the length of time This project will also improve 6Mt of carbon per year between required. Therefore, in order to ADEME’s Climagri® tool, used 1990 and 1995, and 1999 to evaluate policies which impact in greenhouse gas diagnoses 2004. However, these changes on soil management and carbon within territorial climate-energy are spatially highly variable and stocks, modelling is needed to plans (PCEAT).

Soil and carbon l 25 Perspectives Improving and sharing references

In order to improve the inclusion of soil carbon in environmental assessments, some uncertainties still have to be resolved. Nevertheless, tools to support the agricultural sector and local communities are being developed.

soil fertility and integrate all GHG soil emissions, biodiversity, par- particularly nitrogen protoxide

ticularly through (N2O) derived from the degra- the maintenance dation of organic matter and or increases in crop fertilisers. stocks of organic matter. In order TAKING SOILS INTO to facilitate the ACCOUNT IN DECISION inclusion of soil SUPPORT SYSTEMS carbon in national Whether at the field or territorial and local policies, scale, decision support systems it is necessary including soil carbon are being to resolve some developed. Their improvement uncertainties. We and distribution will support need to expand farmers, agricultural advisers the references and local authorities in making

© Claire chenu © Claire available to pro- choices and recommendations. vide a better At the supply chain level, inclu- Including soil criteria in life-cycle representation of ding soil in product life-cycle analysis of food products will territorial diversity and different analysis, especially for food help to better guide agricultural land uses. To achieve this, new and bio-products, would make practices in the long run. experimental data depicting it possible to include soil carbon carbon dynamics in the longer in procurement and production term needs to be acquired, and system decision making. These oils and the carbon they existing data should be pooled. tools still need to be created for store are linked to many There is important work to be forest and urban soils. Finally, environmental issues. conducted on forest soils, in the focus should not only be They play a major role overseas territories and in urban on carbon, but include the Sin climate regulation, but also in areas. For a climate-based other environmental services preserving air and water quality, approach, this work has to provided by soils.

26l Soil and carbon Improving and sharing An international dynamic references to combine food security and climate change mitigation

griculture can and must adapt agricultural practices with same amount would double be part of the solution the goal of storing carbon more the emissions. Managing and to climate change. efficiently in the soil. An annual increasing organic matter in In 2015, France is ‘4 per 1,000’ (0.4%) increase agricultural soil is a way to Alaunching the ‘4 per 1,000’ in organic matter in soil would reconcile soil preservation, food carbon sequestration programme be enough to compensate the security and climate change for agriculture. This international global emissions of greenhouse mitigation. research programme aims to gases. Conversely, a loss of the

The ‘4 per 1,000’ Fighting climate change by storing carbon in soil biomass

“This international research programme combines the objectives of food security and climate change mitigation, and can therefore involve all the countries in COP 21” Stéphane LeFoll, Minister of Agriculture, Food and Forests

Carbon Carbon Greenhouse gas Soils worldwide emitted stored in = ratio emissions from contain 2,400 8.9 2 400 in CO2 organic 0.4% fossil carbon billion tonnes of form form represent 8.9 organic carbon billion tonnes of

carbon per year CO2 absorption by plants so, if we increase carbon stored in soil by 0.4%,

we compensate for CO2 emissions from fossil carbon, which are mainly responsible for the 8.9 greenhouse effect and climate change.

Increase in CO2 absorption by plants: agricultural land, grassland and forests CO2 emissions Organic carbon CO2 storage in soils emissions

+0.4% carbon stored in soil 2 400 worldwide

= 0 CO2 emissions in the air

Soil and carbon l 27 Research ADEME supports research for better agricultural and environmental management of soil organic matter

ware of the importance to the fluxes of three main green- gation. Work began in 2012 and of soil preservation and house gases (GHG). These gases 18 projects are currently aiming

organic matter mana- are nitrous oxide (N2O), to provide a better understanding

gement, ADEME has (CH4) and (CO2). of the effect of land use (agricul- Asupported science for several Research questions linked to the tural land, grassland and forest) decades through research and role of soil in climate change have and management of the GHG thesis programmes (for example, been integrated in the ‘REACCTIF’ balance in France and overseas the GESSOL programme)*. call for projects (Research on territories. Furthermore, projects In 2010, research actions were climate change mitigation through for a better integration of soils in launched to provide a better agriculture and forestry) in order climate policies, environmental understanding of soil and climate to highlight strategies for carbon assessments and ISO standards interactions because soils contribute storage in soil and emissions miti- have also been launched.

The 18 research programmes chosen which include soil as an important dimension in climate change mitigation (REACCTIF project) in agriculture and forestry.

Theme Coordinator Title Deliverables

Fabien LIAGRE AGRIPSOL – Agroforestery for preserving • Measuring protocols Crops (AGROOF) soil • Assessment of agricultural practices

Cornelia RUMPEL AEGES – Mitigation of GhGs emissions • Assessment of agricultural practices Grasslands (CNRS) in grasslands. • Modelling

• Assessment of agricultural practices CiCC – Cover crops for mitigating Crops Eric JUSTES (INRA) • Modelling climate change • Decision support tool

Caroline SYSCLIM – Crop systems Crops COLNENNE-DAVID • Assessment of agricultural practices and climate change (INRA)

EFFEMAIR N2O – Modelling and assessment Joël LEONARD of the effect of environmentally-friendly • Assessment of agricultural practices Crops (INRA) practices on microbial activities and N2O • Modelling emissions from soils.

* The GESSOL programme is coordinated by the French Ministry of Ecology, www.gessol.fr

28l Soil and carbon ADEME supports research Theme Coordinator Title Deliverables Catherine HENAULT Crops SOLGES – Ability of soil to reduce N O. • Assessment of agricultural practices for better agricultural and (INRA) 2 Safya ETYC – Integrated assessment of the Livestock MENASSERI-AUBRY treatment ant the recycling of organic • Assessment of agricultural practices breeding (AGROCAMPUS matter in livestock systems designed to environmental management of OUEST) mitigate climate change.

Annette MORVAN- P2C – Plant : major actor of the capture soil organic matter Grasslands BERTRAND of atmospheric carbon and its transfer to • Assessment of agricultural practices (University of Caen) grassland soils.

CSopra – Accounting methods of soil • New accounting methods Manuel MARTIN Crops carbon sequestration in French agricultural • Modelling (INRA) soils. • National Inventory

Annie DUPARQUE ABC’TERRE – Mitigation of GHG emissions • Regional Inventory Crops (AGRO-TRANSFERT from agriculture and carbon sequestration • Decision support tool RT) at regional scale.

SOCLE – Accounting the effect on soil Crops and lives- Cécile BESSOU • LCA Methodology carbon of land use and land-use changes in tock breeding (CIRAD) • Decision support tool Life Cycle Analysis of agricultural products.

C@RUN – Storage/sequestration of carbon Pierre TODOROFF Crops in the agricultural soils of the Reunion • Regional Inventory (IRD) Island (France)

TropEmis – Regional assessment of soil Jorge SIERRA • Regional Inventory Crops carbon sequestration or emission in the (INRA) • Decision support tool tropical soils of Guadeloupe (France)

Michel BROSSARD Crops CarSGuy – Soil carbon in French Guyana • Regional Inventory (IRD)

Daniel EPRON EMEFOR – Effect of soil compaction on CO Forests (University of 2 • Assessment of forest management and CH exchanges in forest soils. Lorraine) 4

CESEC – Analysis of long times series

Crops, Forests, Bernard LONGDOZ of net exchanges of CO2, water vapor • Assessment of forest, Grasslands (INRA) and radiation in forests, grasslands and crop and grassland managements croplands.

Lauric CÉCILLON piCaSo – Effet of forest management and Forests • Assessment of forest management (IRSTEA) soil type on carbon stocks in forest soils.

Laurent RESPIRE – Harvesting of wood residues : Forests SAINT-ANDRÉ potential, impact and remediation by • Assessment of forest management (INRA) spreading of ashes.

Soil and carbon l 29 Research

Organic Carbon per country in peta grams (Pg) European top soils contain more than 70 billion tonnes of organic carbon. The European soil database, at a scale of 1:1,000,000, is one of the most homogeneous and comprehensive databases on the organic carbon/ matter content of European soils. It also includes information from associated databases on land cover, climate and topography.

Deep soil carbon: a reservoir not to be neglected! The first estimates of deep soil carbon stocks in France have been produced by INRA using data from GIS Sol and ISRIC. Soil profiles have been modelled down to 1m across France following the specifications of the GlobalSoilMap programme (www.globalsoilmap.net). In France, 35 to 60% of total organic carbon could be sequestered deeper than the first 30cm. Biological and human factors predominate at the surface while abiotic factors, such as soil parent material, become more important with depth. These estimates remain highly uncertain. However, they indicate that soil may have a larger potential to sequester carbon than usually reckoned.

Expert Luca Montanarella opinion Senior Expert, European Commission DG JRC.H5

Soil organic carbon matters in the European Union “EU soils contain more than 70 billion tonnes of organic carbon, which is equivalent to almost 50 times our annual greenhouse gas emissions. However, intensive and continuous arable production may lead to a decline in soil organic matter. In 2009, European croplands emitted an average of 0.45 tonnes 1 of CO2 per hectare (much of which resulted from land conversion) . The conversion of peatlands and their use is particularly worrying. For instance, although only 8% of farmland in Germany is on peatland, it is responsible for about 30% of the total greenhouse gas emissions of its whole farming sector2. However, with appropriate management practices, soil organic matter can be maintained and even increased. Apart from peatlands, particular attention should be paid to the preservation of permanent pastures and the management of forest soils, as carbon age in the latter can be as high as 400-1,000 years3. Keeping carbon stocks is therefore essential for the fulfilment of present and future emission reduction commitments of the EU. Soil organic carbon is the major component of soil organic matter that improves the physical properties of soil, as it stores a great proportion of nutrients necessary for plant growth.”

1 http://www.eea.europa.eu/publications/european-union-greenhouse-gas-inventory-2011. 2 http://ec.europa.eu/environment/soil/pdf/report_conf.pdf, p. 17. 3 Ibid., p. 13.

30l Soil and carbon Expert Isabelle Feix opinion National soil expert at ADEME

Organic matter fuels agroecology “Agroecology returns agronomy to the centre of agricultural practices. Soils, and the organisms living in it, are one of the driving forces of agroecology, with organic matter providing the fuel. Depending on its degradation stage, organic matter supplies nutrients for plants, contributes to soil stability, maintains water reserves, provides a home to soil-living organisms and contributes to good root structure for crops. The good management of soils is essential to improve production systems. A healthy soil makes it possible to rationalise inputs of fertilisers, water and even plant protection products, and also improves crop vigour. To ease the implementation of agroecology, research has to focus on soils and work in a sector-approach, in conjunction with technical institutes and farmers. It has to prove that other sustainable production systems, identified according to the nature of the soil, can be implemented. It also has to guarantee the durability of systems which ensure soil carbon stocks are maintained or increased by assessing their environmental, economic and social impacts. This approach will avoid later problems, for example, a system which provides environmental benefits through carbon storage but

creates other problems, such as increased N2O emissions or greater use of plant protection products.”

Main references Thanks

• ADEME, AFOCEL, IDF, UCFF, INRA, 2008. La Report of the Intergovernmental Panel on To contributors and proofreaders: récolte raisonnée des rémanents. Collection Climate Change. Cambridge University Press, Véronique Antoni (MEDDE), Connaître et Agir de l’ADEME. 40 p. Cambridge, United Kingdom and New York, Dominique Arrouays (INRA), NY, USA, 1535 pp • Agro-Transfert Ressources et Territoire Laurent Augusto (INRA), Marion Bardy (INRA), (coord.) 2012. Gérer l’état organique des • Pellerin S. et al. 2013. Quelle contribution Marc Bardinal (ADEME), Eric Blanchart (IRD), de l’agriculture française à la réduction des sols dans les exploitations agricoles. Antonio Bispo (ADEME), émissions de gaz à effet de serre ? Potentiel • Arrouays D., Balesdent J., Germon JC., d’atténuation et coût de dix actions techniques. Alain Bouthier (Arvalis-Institut du Végétal), Jayet PA., Soussana JF., Stengel P., 2002. Synthèse du rapport d’étude, Étude INRA- Michel Brossard (IRD), Contribution à la lutte contre l’effet de ADEME-MAAF-MEDDE. Claire Chenu (AgroParisTech), serre, Stocker du carbone dans les sols Vincent Colomb (ADEME), agricoles de France ? Synthèse du rapport • Meersmans J. et al. 2012. A high resolution Annie Duparque (Agro-Transfert RT), d’expertise scientifique réalisé par l’INRA à map of French soil organic carbon. Agronomy la demande du Ministère de l’Écologie et du for Sustainable Development, 32(4), 841-851. Isabelle Feix (ADEME), Développement durable, 33 p. • Landmann G., Nivet., C. (coord.) 2013. Projet Christian Feuillet (MEDDE), Jean-Luc Fort (Chambre d’agriculture Poitou- • Calvet R., Chenu C., Houot S. 2011. Les Resobio. Gestion des rémanents forestiers : matières organiques des sols : rôles agro- préservation des sols et de la biodiversité. Charentes), nomiques et environnementaux. Éditions Angers : ADEME, Paris : ministère de l’Agri- Chantal Gascuel (INRA), France Agricole. 347 p. culture, de l’Agroalimentaire et de la Forêt Camille Guellier (ADEME), Françoise Juille (INRA) - GIP Ecofor. Rapport final, 248 p. • Duparque, Annie, Vincent Tomis, Bruno Jérôme Labreuche (Arvalis-Institut du Végétal), Mary, Hubert Boizard, et Nathalie Damay. • UE, 2013. Décision 529/2013/EU relative aux Sandrine Leménager (MAAF), 2011. “ Le bilan humique AMG, pour une règles comptables concernant les émissions Joseph Lunet (MEDDE), Manuel Martin (INRA), et les absorptions de gaz à effet de serre démarche de conseil fondée sur des cas- Sarah Martin (ADEME), résultant des activités liées à l’utilisation types régionaux ”. In : 10es rencontres de Dorothée Pageaud (MEDDE), des terres, au changement d’affectation la fertilisation raisonnée et de l’analyse de des terres et à la foresterie (UTCATF) et Sylvain Pellerin (INRA), terre. GEMAS-COMIFER. Reims : 16 p aux informations concernant les actions Caroline Rantien (ADEME), • GIS Sol. 2011. L’état des sols de France. liées à ces activités. Olivier Scheurer (Institut LaSalle-Beauvais), Groupement d’intérêt scientifique sur les • Vigot M., 2012. Le carbone organique des Nicolas Saby (INRA), sols, 188 p. sols cultivés de Poitou-Charentes ; quanti- Marie-Françoise Slak (IGN), • IPCC, 2013: Climate Change 2013: The fication et évolution des stocks. Chambre Audrey Trevisiol (ADEME), Vivescia. Physical Science Basis. Contribution of d’agriculture de Poitou-Charentes/RMT Luca Montanarella (JRC) Working Group I to the Fifth Assessment Sols et territoires. 24 p.

Soil and carbon l 31 ADEME in brief

The French Environment and Energy Management Agency (ADEME) par- ticipates in the implementation of environmental, energy and sustainable development policies. The agency helps companies, local authorities, govern- Organic carbon in soils “Meeting climate change and food security challenges ment bodies and the general public through its expertise and advisory Farmland and forests occupy more than 80% of the French territory capacities, allowing them to establish and currently store 4 to 5Gt of carbon (including 15 to 18Gt of CO ), with more than two-thirds of this carbon stored in top soils. and consolidate their environmental 2 Any positive or negative fluctuation of this stock influences national actions. Furthermore, ADEME helps greenhouse gas (GHG) emissions, which are estimated at 0.5Gt

finance projects, from research through CO2 eq/year (2011). The agricultural and forestry sectors also offer solutions for climate change mitigation through the production of to implementation, in the following do- renewable energies and preserving or increasing carbon stocks in mains: waste management, land conser- soils and biomass. The management of organic matter, which is vation, energy efficiency and renewable the principal carbon reservoir in soils, is a key determinant in the capacity of soils to produce food and material and to offer other energies, air quality and noise pollution. environmental services such as the regulation of water cycles and ADEME is a public institution under air quality etc. Acting on soil carbon stocks also means acting on the joint supervision of the Ministry soil and environmental quality. This is the sense of the ‘4 per 1,000’

initiative proposed by France at COP21. Drawing on data from the

of Ecology, Sustainable Development GIS Sol database, this brochure highlights the important role of soil and Energy and the Ministry of Natio- carbon in French climate change mitigation strategies. In order to nal Education, Higher Education and address soil and climate change challenges, the main agricultural and “ forestry levers for action are presented. An inventory of evaluation Research. tools, from the field to the national scale, will help managers and www.ademe.fr. advisers to better direct practices. Print by Pure impression Certifications impression 2015 І Print Pure by PEFC - ISO 9001 14001- imprim’vert І ISBN 979-10-297-0209-9 November 8575 500 ex.

En partenariat avec

ADEME 20, avenue du Grésillé - BP 90406 www.ademe.fr49004 Angers cedex 01