Use of urban composts for the regeneration of a burnt Mediterranean soil: A laboratory approach
Résumé
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, we
determined 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 waste
compost (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 soil
characteristics were measured during 77-day incubations in microcosms. The impact of composts input
on hydrological behaviour related to erodibility was estimated by measuring runoff, retention and
percolation (i.e. infiltration) of water using a rainfall simulator under laboratory conditions. Input of
composts increased organic matter and soil nutrient content, and enhanced C and N mineralisation and
total 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 significant
effect compared to the control. Composts mixed with soil weakly limited runoff and infiltration whereas
composts laid at the soil surface significantly reduced runoff and increased percolation and retention,
particularly with the MWC.