Is it efficient to co-compost and co-vermicompost green waste with biochar and/or clay to reduce CO2 emissions? A short-term laboratory experiment on (vermi)composts with additives.

Is it efficient to co-compost and co-vermicompost green waste with biochar and/or clay to reduce CO2 emissions? A short-term laboratory experiment on (vermi)composts with additives.. EGU, European Geosciences Union General Assembly 201

Composting with additives to improve organic amendments. A review

Composting and vermicomposting are sustainable strategies to transform organic wastes into organic amendments, valuable as potting media or soil conditioner. However, the negative aspects of these processes are emissions of greenhouse gases and odorous molecules and final product potentially containing toxic compounds. These negative aspects can be limited through the addition of organic, inorganic or biological additives to the composted or vermicomposted mixture. The aims of this review are (1) to present the main characteristics of composting and vermicomposting processes with and without additives, (2) to show the influence of additives on greenhouse gas emissions during waste degradation and (3) to report the effects of additives on the properties of the final products (heavy metal and nutrient contents), in view of their use as a soil conditioner or potting media. Finally, the feasibility and potential environmental benefits of co-composting and co-vermicomposting are discussed. Our results show that additives affect composting parameters such as temperature, pH and moisture and thus have an impact on the composting process. They may be used to reduce gas emissions and mobility of mineral ions. The various additives have contrasting effects on the quality of the final product and its impact on soil quality. The use of worms and additives seems to increase plant available nutrient contents, while decreasing N leaching, heavy metal mobility and composting time. Co-composting and co-vermicomposting strategies need to be locally optimised, involving the generated amendments in a circular economy to improve sustainability of agricultural systems

Composting with additives to improve organic amendments. A review

International audienceAbstractComposting and vermicomposting are sustainable strategies to transform organic wastes into organic amendments, valuable as potting media or soil conditioner. However, the negative aspects of these processes are emissions of greenhouse gases and odorous molecules and final product potentially containing toxic compounds. These negative aspects can be limited through the addition of organic, inorganic or biological additives to the composted or vermicomposted mixture. The aims of this review are (1) to present the main characteristics of composting and vermicomposting processes with and without additives, (2) to show the influence of additives on greenhouse gas emissions during waste degradation and (3) to report the effects of additives on the properties of the final products (heavy metal and nutrient contents), in view of their use as a soil conditioner or potting media. Finally, the feasibility and potential environmental benefits of co-composting and co-vermicomposting are discussed. Our results show that additives affect composting parameters such as temperature, pH and moisture and thus have an impact on the composting process. They may be used to reduce gas emissions and mobility of mineral ions. The various additives have contrasting effects on the quality of the final product and its impact on soil quality. The use of worms and additives seems to increase plant available nutrient contents, while decreasing N leaching, heavy metal mobility and composting time. Co-composting and co-vermicomposting strategies need to be locally optimised, involving the generated amendments in a circular economy to improve sustainability of agricultural systems

Worms and minerals influence the biogeochemistry and turnover of composted organic matter

Worms and minerals influence the biogeochemistry and turnover of composted organic matter. 28 th International Meeting on Organic Geochemistr

The impact of soil fauna on C turnover and formation of organo-mineral associations

The impact of soil fauna on C turnover and formation of organo-mineral associations. 6th International Symposium on Soil Organic Matte

Addition of clay, biochar and their mixture during composting with earthworms: a strategy to reduce carbon emissions?

Addition of clay, biochar and their mixture during composting with earthworms: a strategy to reduce carbon emissions? . III International Symposium on Organic Matter Management and Compost Use in Horticultur

The effects of worms, clay and biochar on CO2 emissions during production and soil application of co-composts

In this study we evaluated CO2emissions during composting of green wastes with clay and/or biocharin the presence and absence of worms (species of the genusEisenia), as well as the effect of those amendmentson carbon mineralization after application to soil. We added two different doses of clay, biochar or their mixtureto pre-composted green wastes and monitored carbon mineralization over 21 days in the absence or presenceof worms. The resulting co-composts and vermicomposts were then added to a loamy Cambisol and the CO2emissions were monitored over 30 days in a laboratory incubation. Our results indicated that the addition ofclay or clay/biochar mixture reduced carbon mineralization during co-composting without worms by up to 44 %.In the presence of worms, CO2emissions during composting increased for all treatments except for the lowclay dose. The effect of the amendments on carbon mineralization after addition to soil was small in the shortterm. Overall, composts increased OM mineralization, whereas vermicomposts had no effect. The presence ofbiochar reduced OM mineralization in soil with respect to compost and vermicompost without additives, whereasclay reduced mineralization only in the composts. Our study indicates a significant role of the conditions ofcomposting on mineralization in soil. Therefore, the production of a low CO2emission amendment requiresoptimization of feedstocks, co-composting agents and worm species

Increasing soil organic matter by adding compost or vermicompost stabilized with clay and/or biochar

International audienc

Worms and minerals influence the biogeochemistry and turnover of composted organic matter

International audienc

Earthworms affect biogeochemical cycling through their impact on carbon and nitrogen stabilization by mineral interactions

International audienceStabilization of organic matter (OM) is an important process controlling the coupling and decoupling of biogeochemical cycles and their role in mitigating climate change. Soil organisms, particularly earthworms, may greatly influence these processes through their potential impact on the interaction of OM with soil minerals ; a mechanism which may protect soil organic matter (SOM) at medium (years) and long (decades, centuries) time scales. The aim of this study was to use earthworms and pure minerals in order to enhance the formation of organo mineral interactions during a 6 month decomposition experiment. Our experimental approach was based on the comparison of OM decomposition without minerals and OM decomposition with minerals (70% fresh OM & 30% Montmorillonite). These treatments were establish with and without the simultaneous presence of two epigeic earthworm species (Eisenia andrei and Eisenia foetida). We used density fractionation of the end-products to isolate several fractions : water soluble OM, free particulate OM, mineral associated OM (>1.6 g cm3 and >1.8 g cm3). The fractions were characterised by elemental analyses, electron microscopy and Rock Eval pyrolyses to investigate the effect of earthworms on the allocation of C and N compared to treatments without worms. Presence of minerals led to the formation of organo-mineral complexes in the heavy fractions, while for pure OM treatments heavy fractions were absent. Indeed, the addition of minerals during the decomposition process resulted in the transfert of 70% of carbon and nitrogen from soluble and particulate OM to heavy fractions. With worms more C and N were allocated to the >1.8 g cm3 fractions as compared to treatments without worms. Indeed, worms led to highest C contribution in the 1.6-1.8 g cm3 fraction. Moreover, earthworm presence led to the formation of black cristalline particles in the heaviest fraction. Information about the morphology and stability of organo-mineral complexes will be presented. We conclude that the presence of earthworms impact biogeochemical cycling of C and N through influencing the stabilization of OM by interaction with minerals