Microbial communities from different soil types respond differently to organic waste input

Using organic waste products (OWP) in agriculture has been reported to impact both the activity and composition of soil microbial communities. However, little information is available on how the response of a soil microbial community to a given OWP may depend on the physicochemical and microbial properties of the soil receiving the input. Here, we performed a microcosm experiment to compare the effect of 2 different OWPs (GWS: co-compost of Green Wastes and Sewage sludge or FYM: FarmYard Manure), each applied to 5 different soils, on the activity, abundance and diversity of the soil microbial communities. Soils were selected to represent a range of physicochemical and climatic characteristics. CO2 and N2O emissions, microbial biomass and taxonomic diversity were monitored for 28 days following OWP input. The five soils presented different prokaryotic and fungal communities structures before OWP application. During the 28 days of incubation, those control soils (without OWP) harboring the highest organic matter contents released the greatest CO2 and N2O emissions, and had the highest soil microbial biomass. The impact of organic amendments on soil activity and microbial diversity differed with the nature of the OWP. FYM application increased CO2 emissions 2-fold and delayed N2O emissions compared to GWS. Major changes in prokaryotic genetic structures were also observed when GWS was applied. The effect of OWPs was dependent on soil type and the five soils exhibited distinct patterns of CO2 and N2O emission after a given input. This accorded with the fact that the structure and composition of the microbial communities harbored by each soil type responded differently to a given OWP application. To conclude, our results show that different soil types, harboring distinct microbial community structures, responded differently to OWP application, leading to different patterns and rates of greenhouse gas emissions. This response was also OWP-dependent.