Soils with low organic matter and modest biological activity show a reduced capacity to produce goods and services. The use of biochar as soil amendment improves physical and chemical fertility and has positive effects on soil microbial communities acting as structural habitat for microorganisms. This study investigates the capacity of biochar to support inoculation of the microbial biomass in low-fertility soils. Biochar was produced from olive pomace by a slow pyrolysis process under N2 (450° C for 1h) using an experimental reactor. Microbial biomasses from a fertile soil and from a commercial compost were extracted by glycerol (1%) and sodium pyrophosphate (0.1%) solution and incubated in 1/10 strength Tryptic Soy Broth (TSB). Biochar was then added to TSB to allow microbial colonization. The degree of colonization was checked by SEM and quantified by plate count.
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The inoculated biochar was incorporated into a sandy soil at doses of 10 and 30 t/ha. The increase of the microbial biomass in the sandy soil was measured by plate counting and fumigation-extraction method. Despite the short residence time, the microbial biomass significantly increased, confirming the potential use of biochar as microorganism carrier to improve soils characterized by poor biological parameters.
