ST2. Biomasses

Managing, producing and recycling biomasses for multiple purposes

Sophie Genermont, helped by Florent Levavasseur, Céline Richard-Molard and Benoît Gabrielle.


Nowadays, the recycling of organic wastes is largely encouraged and forms part of circular economy (EU circular Economy Package). Non-food crop cultivation to produce biomass for bioenergy or biomaterials purposes is also developing as part of the bioeconomy. ECOSYS has acquired an internationally recognized position for: (i) the development of renewable energy based on non-food crops, and (ii) biomass recycling to improve soil quality and crop production, through nutrient recycling, substitution of mineral fertilizers and soil organic carbon storage, taking care of potential associated environmental impacts.

In the next future, more attention will be dedicated to the integration of results, sectors being explored as a whole (considering field and process treatment), either in biofuel production, or in husbandry as well as urban and agro- industrial waste management sectors. Furthermore, competition is growing for access to organic resources between agriculture and other bio-economic sectors. Many stakeholders have to be considered in the understanding of organic biomass production, management and fluxes within territories. Providing guidance for their best use as a function on the local context and opportunities is a key challenge.

The gradient from full agricultural regions to peri-urban context is of particular relevance for this “biomasses” structuring theme. The variety of agricultural systems concerned by waste recycling is considered: from the exceeding areas with off-land husbandry or mixed farming livestock (e.g., Brittany where several collaborative projects involve ECOSYS) to areas with potential high need for alternative organic sources (typically grain plains in the Paris Basin). Additionally, ECOSYS is increasingly considering less conventional systems developing in urban areas. Cities are intensive waste producers, and ECOSYS will contribute to the optimization of their recycling (see RL1 in Soil team). Urban farm, market gardening and increasing conversions towards organic farming near cities are emblematic of short recycling and food production chains, and constitute new fields of investigation for ECOSYS researches. The mobilization of marginal lands (fallow lands) for the production of non-food crops is also one of the issues for the next few years.

ECOSYS inputs will focus on processes occurring at the field and territory scales with time horizons ranging from days to decades, and through large use of modeling. ECOSYS is more and more focusing on territorial management of biomasses, either as wastes or as feedstock supply to industrial processes, involving stakeholders and their decision- making rules. This has been supported by the recent recruitment of a research engineer in Soil team (Florent Levavasseur). Other levels including waste treatment for example, will be addressed in collaboration with other INRAE teams, Technical Institutes, waste producers... Incidentally, process studies at smaller scales will remain necessary to better account for specific processes (e.g., plant absorption of nutrients, physico-chemical parameters of ammonia volatilization,…).

ECOSYS not only studies the feed-back effects of these biomass management strategies at several spatial levels but contributes to the evaluation a priori of the viability and the resilience of new cropping systems arising. The main benefits addressed are: the contribution to renewable energy production, mineral fertilizer substitution, soil C storage, soil biodiversity and biological functioning. The ecosystem environmental impacts addressed by ECOSYS concern all compartments, including soil, water, atmosphere, and biosphere; studies deal with local impacts (increase in contaminant concentrations potentially leading to toxicity, eutrophication, decrease in biodiversity, acidification…) and global changes (particularly climate change). Multi-criteria approaches including positive and negative impacts are used for assessment and optimization of those managements and land-uses. Life cycle assessment is currently used for non- food crops and bio-based value chain, and would be extended to waste management and recycling, together with the use and/or production of relevant indicators to deal with ecosystem services.

Scientific questions and objectives

The main objective is to produce knowledge enabling the compliance of non-food biomass production and waste biomass recycling with agroecology principles and to assess their positive and negative effects on the ecosystem services they deliver. We identified knowledge gaps or improvement routes that require further research. As far as biophysical processes are concerned, they are addressed within the disciplinary teams: most of the research questions developed here cut across these teams. Four main objectives will drive our research in the next future, initiated within contributing projects (examples are mentioned).

1.     Towards increased genericity

The genericity of the approaches is a prerequisite to the extrapolation of our research to all new biomasses produced by agricultural activities and/or recycled in agriculture. It can only be achieved by an efficient typology of biomasses with regard to the services and disservices addressed. One challenge of the research in the next future is thus to develop typologies to predict the potential nutrient availabilities, carbon storage and environmental impacts (ammonia volatilization, GHG emission, contaminant contents…) based on characteristics and production chain of the recycled biomasses. Such typologies are necessary for parameterization of models or decision tools. Agro-ecosystem models are another means of ensuring this genericity although they are data-intensive and require complex tests. Meta-models or meta-analyses may provide a simpler, more robust alternative so far as primary data is available at ECOSYS and in the literature (under progress for ammonia volatilization).

2.     Focus on plants

A set of questions specific to plants has recently arisen in relation to biomass recycling that will be addressed by developing interactions with ecophysiologists through innovative scientific project proposed to INRAE, AgroEcoSystem division. How does biomass recycling modify root development and what are the consequences on soil C excretion and soil N uptake by the crops? How to really account for “cash crops” in the recycling sector and how may cash crops adapt to increasing biomass recycling? Can we choose plants to optimize the treatment/recovery processes? The addressed questions will be:

  • is there any differentiated comportment of species and/or varieties for a valuable recycling of organic biomasses? Which species and/or varieties are the best ones?
  • by which processes plants adapt for a better use of N originating from organic recycled biomasses? Can we isolate a specific eco-physiological adaptation trait that will also  be able to  describe plant nutrient translocation, link it to crop yield and production quality?

3.     Potential trade-off between carbon storage, nitrogen availability and environmental impacts

The potential C storage after recycling of organic biomasses has been demonstrated and related with the origin and treatment of recycled organic biomasses. The objective is now to focus on the consequences on the dynamics of stored C compared to other C sources in soils. The biogeochemical cycles of C and N are strongly coupled and C storage may decrease N availability in soil. We plan to determine the best trade-off between C storage and N availability depending on the origin and the treatment of the organic biomass available.

On the other hand, C storage and mineral N substitution by organic recycling may have impacts on gas emission (greenhouse gas but also ammonia and COV). The environmental assessment of C and N as affected by the inputs of recycled organic biomasses or the switch to non-food crops has to be considered. Additionally, these assessments have to be considered for the entire chain including treatment and application in agriculture for recycled organic biomasses.

The effect of various land-use transitions to non-food crops on water, C and N dynamics at landscape scale will also be investigated.

4.     Multi-criteria evaluation for optimization:

A multi-criteria evaluation tool for the integration of organic recycled biomasses into cropping systems will be developed and used for the development of innovative cropping systems and for the territorial management of organic recycling, taking into account stakeholders.  This includes (i) the choice of relevant criteria and their indicators to be considered in the multi-criteria assessment of cropping systems with non-food crops and/or organic recycling, (ii) the definition of threshold values for diagnosis. The environmental impacts related to the biomass production and recycling (input of contaminants, pathogens, gas emissions…) will be considered in the multi-criteria evaluation. Based on this multi- criteria assessment tool, innovative cropping systems including non-food crops and/or recycled organic biomasses will be tested using a multi-agent platform (MAELIA) to consider the decision rules of the farmers and other relevant stakeholders (waste treatment, …). This has started within the PROLEG and PROTERR projects.

For non-food crops, the impact of land-use change on their environmental balance will be assessed, as a function of prior land-use (cropland, grassland, unproductive fallow or marginal land). The results of all scenario simulation will be then used to optimize the production and recycling of biomasses at spatial scales.

Insertion within ECOSYS and collaborations

The “Biomasses” theme features strong links with the other ECOSYS structuring themes and strong cross-cutting ties with the disciplinary teams. Both land-use change and new cropping systems and practices including alternative sources of nutrients (recycled biomass, non-food crops) contribute to agriculture adaptation and mitigation to global changes (particularly climate change), clearly pointing the links with the “climate” theme. The new land-uses and land management practices also contribute to the increase in diversity and in the resilient nature of agro-ecosystems (see “diversity” structuring theme).The impacts emerging on new contaminant emissions are fully addressed in the “contaminant” theme: especially VOC emissions, which were found significant for both non-food crops and soils treated with composts, organic contaminants as for example pharmaceutical compounds in the specific cases of recycled organic biomass. The “biomasses” theme questions the “contaminants” theme to assess ecotoxicological impacts of some chemical or organic substances which may be hidden by confounding effects due to the potential stimulating effect of organic matter, including nutrient availability for biological organisms.

The “biomasses” structuring theme would enable and need the mobilization of data acquired on ECOSYS long term sites (e.g., QualiAgro, ICOS), and even the SOERE-PRO to characterize and quantify the potential services and disservices to further use them for parameterization of the multi-criteria assessment tools (done within the PROTERR project). Other well equipped field experiment could be used to assess the impact of land-use changes (ASSET). We have started working at spatial and territory scales and will continue working on explored territories such as peri-urban territories of “Plaine de Versailles” and “Plateau de Saclay”. This requires knowledge of spatial distribution of soil types and characteristics, soil occupation, farmer practices… The skills in geomatics present in ECOSYS will largely contribute to this theme.

Disservice assessment will rely on the mobilization of the ECOSYS analytical platforms. Typological approaches will be made possible by using adapted screening tools already available for assessment of N availability or certain gaseous emissions (e.g, NH3 and N2O, as services in the “AgroSystèmes” Business Unit), but still needing to be refined or even invented for other issues (e.g. organic matter characterization or other gaseous emissions like VOC). This will seek ECOSYS capacity to technically innovate within the technical teams.

Although based on the resource skills of the disciplinary teams of ECOSYS, these topics will require to developing further collaborations with other scientists, technical institutes, cooperatives, stakeholders… both at the national and international levels (through European projects such as MAGIC on biomass production on marginal land, or the ASSETS flagship project of the LabEx BASC and PROLEG at the territorial level). Strong links with technical institutes are of particular interest for this structuring theme (UMT Alter’N with Terres Inovia, Arvalis,…). For specific studies on plants, collaborations with IJPB have been initiated. The direct collaborations with technical institutes and chambers of agriculture, but also the contribution to technical networks (RMT Fertilisation & Environnement,…) make possible the transfer of results towards practices (PROLEG, EVAPRO projects).

Strong collaborations exist with other scientific teams working on biomass recycling within INRAE (SAS, ISPA, LSE, …) but also other research institutes (Recyclage et Risque - CIRAD; Eco&Sol - IRD). Specific attention will be given to the interactions with the Agronomie and SADAPT units at Versailles-Grignon during elaboration of alternative cropping systems, scenario designs, before their deployment. Interactions with teams (LBE, OPAALE - IRSTEA) and private companies (VEOLIA, SUEZ) dedicated to waste treatment or bio-industries will be continued and reinforced in order to be able to consider the entire production/treatment/application chain. This structuring theme will also contribute and use INRAE modeling platforms: agro-ecosystem modeling (CERES-EGC and STICS, AMG with AgroImpact), MEANS for multi- criteria and life-cycle assessment (SAS unit), MAELIA for spatial management of organic recycling (collaboration with LAE unit).

Modification date: 10 October 2023 | Publication date: 17 July 2019 | By: Sophie Formisano