Soil fungal taxonomic and functional community composition as affected by biochar properties

Abstract

Biochar greatly influences the soil bacterial community and nutrient transformations, while our knowledge of the responses of fungal lifestyles to biochar is still in its infancy. Here, we used experimental pre-treatments (acetone extraction) of nutrient-rich biochars to identify which major biochar properties influence fungi the most: the easily mineralizable C, fused aromatic backbone, or the inorganic nutrients of biochars. Our objective was to investigate how different biochar fractions (easily mineralizable C, fused aromatic C, nutrients) structure the fungal taxonomic and functional communities. The easily mineralizable C of biochars induced greater shortterm changes in fungal community composition compared to the fused aromatic C. The easily mineralizable C significantly decreased the relative abundance of Basidiomycota by avg. 10.6%, while it had no effects on Ascomycota and Zygomycota. Co-occurrence network indicated that saprophytic fungi were self-assembled in the easily mineralizable C-sufficient environment, whereas they were the connectors to interact with other groups when lower amounts of energy in form of mineralizable C were present. Thus, the easily mineralizable C in biochar as a microbial C source probably promoted saprotroph growth, caused them to self-assemble and to enhance their competitive capacity, leading to overall diversity decrease and relative decline of fungal pathogens. The inorganic nutrients had no effects on fungal diversity and saprotroph abundance, while they decreased the relative abundance of Zygomycota. Our study highlighted the important roles of both mineralizable C and inorganic nutrients in modification of the fungal community, and demonstrated that biochar probably favors the growth of saprotrophs over soil-borne fungal pathogens.

Corn and hardwood biochars affected soil microbial community and enzyme activities

“…However, this response was not observed in HB. Contrary to other studies (e.g., Dai et al., 2018; Luo et al., 2017), fungal abundance did not increase with either biochar. As recently reviewed by Palansooria et al.…”

Investigating the Influence of Biochar Amendment on the Physicochemical Properties of Podzolic Soil

“…For example, increasing values of cation exchange capacity (CEC) was reported [14], soil water interaction, and retention (including degraded soils) [15], saturated hydraulic conductivity [16], soil aggregation and stability [17] following soil amendment with biochar. Furthermore, biochar has also been reported to influence soil health by enhancing microbial abundance and diversity in the rhizosphere, as well as modifying the favorable microbial environments by adjusting nutrients, increasing soil pH [18][19][20] and modifying plant growth performance through improved fertility, and direct supply of carbon (C) rich substrates [21,22]. Biochar application or amendment is also well recognized as a useful potential climate change mitigation strategy [23,24].…”

Functional response of the soil microbial community to biochar applications

“…In addition, biochar load and pyrolysis temperature had direct effects on fungal rather than bacterial abundance, which indicates fungi were more sensitive to biochar per se than bacteria. This might suggest that biochar application overall had direct effects on fungal community (Dai et al., 2018), but indirect effects on bacterial community structure (Dai et al., 2016; Meynet et al., 2014).…”

“…Our third hypothesis stems from some observation that the mechanisms through which biochar affects bacteria and fungi are different. Specifically, bacteria have been shown to respond indirectly to biochar whereas fungi have been shown to respond directly (Castaldi et al., 2011; Chintala et al., 2014; Dai et al., 2018; Demisie et al., 2014; Jenkins et al., 2017). For example, fungal abundance is sensitive to the types of biochar used whereas bacterial abundance alteration may result from soil properties change caused by biochar addition.…”