Soil microbial diversity, functionality, and community structure are differently affected by diverse types of biochar

Abstract

Using organic wastes for biochar production represents an innovative approach towaste management, facilitating safe residue disposal while producing a soil amendment by-product. The characteristics of biochar strongly depend on the chemicalcomposition of the feedstock utilised in its production. Consequently, even withinthe same agroecosystem, different types of biochar may produce varying effects onsoil chemistry and biology. In a greenhouse experiment, we assessed the impact ofpoultry manure and peanut shell biochars on soil chemical properties and theireffects on microbial community structure, abundance, diversity and functions analysed through biochemical and molecular approaches. Thus, a two-factor experimental design was established, considering biochar type (poultry manure and peanut shellbiochars) and rate (0%, 1%, and 3% w/w). Our findings highlighted that the intrinsicproperties of biochar significantly influenced its ability to induce changes in the analysed variables. Poultry manure biochar exhibited greater efficacy in increasing soilpH and EC, simultaneously enhancing fungal and total biomasses. Meanwhile, peanutshell biochar increased N content and decreased C/N, slightly impacting fungal andtotal biomasses. The effects of biochars on FAMEs and chemical variables weredose-dependent; the higher the application rate, the greater the observed effect.Interestingly, different biochar types affected distinct bacterial taxa abundances.Among the dominant Phyla, while poultry manure biochar increased the relativeabundance of Chloroflexi and decreased that of Proteobacteria, peanut shell biocharincreased Acidobacteria and reduced Firmicutes phyla. The biochar rate did not affectbacterial abundance. Notably, only peanut shell biochar increased bacterial richness.Poultry manure biochar positively impacted functions related to metabolism, whereasthe effect of peanut shell biochar was less evident. Our study revealed that theintrinsic characteristics of biochar significantly modulate the structure and functionality of the soil microbial community. Therefore, understanding the inherent characteristics of biochar is crucial to promoting the development of specific groups of soilmicroorganisms, thus optimising the cycling of essential nutrients.