Co-composting: An Opportunity to Produce Compost with Designated Tailor-Made Properties

AbstractCo-composting is a technique that allows the aerobic degradation of organic waste mixtures, primarily aiming at obtaining compost that can be used as fertiliser or soil amendment. As compared to the typical composting activity, the main difference is not merely the use of more than one feedstock to start and sustain the biodegradation process, but also the possibility of combining various kinds of waste to obtain 'tailored' products with designed properties, or to reclaim and valorise natural resources, such as degraded soils or polluted soils and sediments. Set up of appropriate co-composting protocols can be a way to optimise the management of waste produced by different sectors of agriculture and industry and also from human settlements. Different formulations can not only optimise the biodegradation process through the adjustment of nutrient ratios, but also lead to the formation of products with innovative properties. Moreover, co-composting can be a technique of choice for the reclamation of soils degraded by intensive agriculture or contaminated soils and sediments. In fact, an appropriate mix of organic waste and soils can restore the soil structure and induce fertility in nutrient-depleted soils, and also remediate polluted soils and sediments through degradation of organic pollutants and stabilisation of heavy metals. While the selection of different mixes of organic waste may lead to the design of composts with specific properties and the potential valorisation of selected waste materials, there are still several factors that hamper the development of co-composting platforms, mainly insufficient knowledge of some chemical and microbiological processes, but also some legislative aspects. This chapter illustrates the progress achieved in co-composting technology worldwide, some key legislative aspects related to the co-composting process, the main scientific and technical aspects that deserve research attention to further develop co-composting technology, and successful applications of co-composting for the reclamation of soils and sediments, allowing their use for cultivation or as growing media in plant nurseries. A specific case study of the production of fertile plant-growing media from sediment co-composting with green waste is also illustrated

A review of source tracking techniques for fine sediment within a catchment

Excessive transport of fine sediment, and its associated pollutants, can cause detrimental impacts in aquatic environments. It is therefore important to perform accurate sediment source apportionment to identify hot spots of soil erosion. Various tracers have been adopted, often in combination, to identify sediment source type and its spatial origin; these include fallout radionuclides, geochemical tracers, mineral magnetic properties and bulk and compound-specific stable isotopes. In this review, the applicability of these techniques to particular settings and their advantages and limitations are reviewed. By synthesizing existing approaches, that make use of multiple tracers in combination with measured changes of channel geomorphological attributes, an integrated analysis of tracer profiles in deposited sediments in lakes and reservoirs can be made. Through a multi-scale approach for fine sediment tracking, temporal changes in soil erosion and sediment load can be reconstructed and the consequences of changing catchment practices evaluated. We recommend that long-term, as well as short-term, monitoring of riverine fine sediment and corresponding surface and subsurface sources at nested sites within a catchment are essential. Such monitoring will inform the development and validation of models for predicting dynamics of fine sediment transport as a function of hydro-climatic and geomorphological controls. We highlight that the need for monitoring is particularly important for hilly catchments with complex and changing land use. We recommend that research should be prioritized for sloping farmland-dominated catchments

A review of source tracking techniques for fine sediment within a catchment

Excessive transport of fine sediment, and its associated pollutants, can cause detrimental impacts in aquatic environments. It is therefore important to perform accurate sediment source apportionment to identify hot spots of soil erosion. Various tracers have been adopted, often in combination, to identify sediment source type and its spatial origin; these include fallout radionuclides, geochemical tracers, mineral magnetic properties and bulk and compound-specific stable isotopes. In this review, the applicability of these techniques to particular settings and their advantages and limitations are reviewed. By synthesizing existing approaches, that make use of multiple tracers in combination with measured changes of channel geomorphological attributes, an integrated analysis of tracer profiles in deposited sediments in lakes and reservoirs can be made. Through a multi-scale approach for fine sediment tracking, temporal changes in soil erosion and sediment load can be reconstructed and the consequences of changing catchment practices evaluated. We recommend that long-term, as well as short-term, monitoring of riverine fine sediment and corresponding surface and subsurface sources at nested sites within a catchment are essential. Such monitoring will inform the development and validation of models for predicting dynamics of fine sediment transport as a function of hydro-climatic and geomorphological controls. We highlight that the need for monitoring is particularly important for hilly catchments with complex and changing land use. We recommend that research should be prioritized for sloping farmland-dominated catchments

How do earthworms affect organic matter decomposition in the presence of clay-sized minerals ?

Clay-sized soil minerals are known to protect organic carbon (OC) from mineralisation by formation of organomineral associations limiting its availability to microorganisms. The impact of soil fauna on these processes is poorly known. The aim of this study was to investigate the effect of earthworms on organic matter (OM) decomposition and association with minerals during a laboratory experiment. We used a model system consisting of fresh OM incubated with and without epigeic earthworms (Eisenia andrei and foetida) in presence of different types and amounts of phyllosilicates (kaolinite, montmorillonite) and an iron oxide (goethite) and combinations of these minerals. Our experimental setup included a high OM:mineral ratio to represent the soil-litter interphase. We monitored OC mineralisation during 196 days. Additionally, we investigated physicochemical parameters and chemical OM characteristics of decomposition products by determination of water-soluble OC (WSOC) and acquisition of solid-state C-13 NMR spectra. We also analysed microscale organisation of the organomineral associations produced with and without earthworms by transmission electron microscopy (TEM). Earthworms enhanced OC mineralisation in all treatments. They also led to greater reductions of OC emissions in the presence of minerals as compared to the mineral-free control, depending on the type and amount of minerals added. The presence of earthworms affected microbial biomass, the concentration of WSOC and increased the contribution of aromatic compounds to OM decomposition products. Microscale analyses by TEM showed that earthworms favoured association of minerals with partly degraded OM along with completely degraded material, while in absence of earthworms only completely degraded OM was associated with minerals. We conclude that earthworms impact OM decomposition through (1) their effect on microbial biomass and the physicochemical parameters of microbial habitat and (2) the formation of OM associations by changing the OM types associated to minerals and possibly by creating closer association of partly degraded OM and iron oxides. The stability of these associations remains to be investigated

How do earthworms affect organic matter decomposition in the presence of clay-sized minerals?

International audienceClay-sized soil minerals are known to protect organic carbon (OC) from mineralisation by formation of organo-mineral associations limiting its availability to microorganisms. The impact of soil fauna on these processes is poorly known. The aim of this study was to investigate the effect of earthworms on organic matter (OM) decomposition and association with minerals during a laboratory experiment. We used a model system consisting of fresh OM incubated with and without epigeic earthworms (Eisenia andrei and foetida) in presence of different types and amounts of phyllosilicates (kaolinite, montmorillonite) and an iron oxide (goethite) and combinations of these minerals. Our experimental setup included a high OM:mineral ratio to represent the soil-litter interphase. We monitored OC mineralisation during 196 days. Additionally, we investigated physicochemical parameters and chemical OM characteristics of decomposition products by determination of water-soluble OC (WSOC) and acquisition of solid-state 13C NMR spectra. We also analysed microscale organisation of the organo-mineral associations produced with and without earthworms by transmission electron microscopy (TEM).Earthworms enhanced OC mineralisation in all treatments. They also led to greater reductions of OC emissions in the presence of minerals as compared to the mineral-free control, depending on the type and amount of minerals added. The presence of earthworms affected microbial biomass, the concentration of WSOC and increased the contribution of aromatic compounds to OM decomposition products. Microscale analyses by TEM showed that earthworms favoured association of minerals with partly degraded OM along with completely degraded material, while in absence of earthworms only completely degraded OM was associated with minerals. We conclude that earthworms impact OM decomposition through (1) their effect on microbial biomass and the physicochemical parameters of microbial habitat and (2) the formation of OM associations by changing the OM types associated to minerals and possibly by creating closer association of partly degraded OM and iron oxides. The stability of these associations remains to be investigated

Guide méthodologique identifiant les enjeux nationaux et transfrontaliers relatifs à la préservation et à la remise en bon état des continuités écologiques et comportant un volet relatif à l’élaboration des schémas régionaux de cohérence écologique : deuxième document en appui à la mise en oeuvre de la Trame verte et bleue en France

Le présent document traduit de façon opérationnelle la mise en oeuvre des principes mentionnés dans le premier volet des orientations nationales. Il vise à assister les partenaires associés à l’élaboration des schémas régionaux de cohérence écologique dans leur travail, et est plus spécifiquement rédigé à l’attention des services des Conseils régionaux et des services régionaux de l'État qui doivent préparer les discussions du comité régional Trame verte et bleue. Une première partie aborde les grands principes d'élaboration de la Trame verte et bleue qui serviront à vérifier sa cohérence nationale. Ils correspondent aux éléments minimum que la Trame verte et bleue doit intégrer. La deuxième partie propose d’une part une présentation synthétique des méthodes qui ont déjà été développées pour mettre en oeuvre une Trame verte et bleue (TVB), et d’autre part pour les régions qui n’ont pas encore lancé leur démarche, une proposition de méthode. La troisième partie expose les outils de mise en oeuvre de la Trame verte et bleue, en ciblant les mesures de nature contractuelle

Ingénierie écologique : action par et/ou pour le vivant ?

International audienceThématique en plein essor, l’ingénierie écologique suscite un intérêt croissant tant dans le monde de la recherche que dans celui des praticiens et gestionnaires de milieux terrestres et aquatiques. Pour mieux définir les contours et les buts de ce domaine, les scientifiques de l’Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (Irstea) se sont mobilisés, rejoints par dix chercheurs et praticiens d’autres instituts et organismes. Ils se sont interrogés sur une définition de l’ingénierie écologique envisagée comme un domaine de conception et d’action où la mobilisation du vivant est essentielle afin de restaurer, conserver ou gérer des milieux, naturels ou anthropisés. L’ingénierie écologique peut-elle être définie comme une action par et/ou pour le vivant ? Peut-elle se prévaloir d’une discipline scientifique qui lui serait propre ? Rendant compte des échanges entre les spécialistes du domaine et synthétisant les points de vue, cet ouvrage étudie l’ingénierie écologique en l’abordant et en la revisitant sous les angles de la sémantique, de l’épistémologie et de l’éthique. Destiné aux scientifiques, enseignants, ingénieurs et techniciens ainsi qu’aux gestionnaires et décideurs, ce livre ouvre de nouvelles perspectives afin de faire avancer la recherche environnementale et favoriser l’innovation au service de l’ingénierie écologique