Use of urban composts for the regeneration of a burnt Mediterranean soil: A laboratory approach

Supplement : "Environmental Risks and Problems, Strategies to reduce them through Biotechnology and Engineering"

International audience

English. In Mediterranean region, forest fires are a major problem leading to the desertification of the environment.Use of composts is considered as a solution for soil and vegetation rehabilitation. In this study, wedetermined under laboratory conditions the effects of three urban composts and their mode of application(laid on the soil surface or mixed into the soil) on soil restoration after fire: a municipal wastecompost (MWC), a compost of sewage sludge mixed with green waste (SSC) and a green waste compost(GWC). Carbon (C) and nitrogen (N) mineralisation, total microbial biomass, fungal biomass and soilcharacteristics were measured during 77-day incubations in microcosms. The impact of composts inputon hydrological behaviour related to erodibility was estimated by measuring runoff, retention andpercolation (i.e. infiltration) of water using a rainfall simulator under laboratory conditions. Input ofcomposts increased organic matter and soil nutrient content, and enhanced C and N mineralisation andtotal microbial biomass throughout the incubations, whereas it increased sporadically fungal biomass.For all these parameters, the MWC induced the highest improvement while GWC input had no significanteffect compared to the control. Composts mixed with soil weakly limited runoff and infiltration whereascomposts laid at the soil surface significantly reduced runoff and increased percolation and retention,particularly with the MWC.