Fungal community is more sensitive to the short-term application of biochar in saline farmland soil than bacterial community

Abstract

Alterations in microbial community structure can serve as critical indicators for assessing the effectiveness of soil salinization remediation. However, the response of microorganisms to biochar addition in salinized soil remains unclear. A biochar addition experiment was conducted on salinized farmland with four biochar application rates: 0 t/ha as control (CK), 20 t/ha (B20), 40 t/ha (B40), and 80 t/ha (B80). The results showed that biochar application increased soil water content (SWC), significantly reduced soil Na⁺ content and sodium adsorption ratio (SAR), and enhanced the availability of nutrients. The contents of available phosphorus (AP) and available potassium (AK) increased with higher biochar application rates. These changes in soil physicochemical properties could alter differences in metabolic composition, consequently influencing the structural characteristics of soil bacterial and fungal communities. Specifically, the relative abundance of Actinobacteria, Bacteroidetes, and Planctomycetes increased in the bacterial community, whereas in the fungal community, the relative abundance of Ascomycota increased and that of Basidiomycota decreased. The richness and diversity indices of the bacterial community initially increased and then decreased with increasing biochar application, reaching a maximum at 40 t/ha; the diversity of fungal species was lower at 40 t/ha than at 20 and 80 t/ha, but their richness gradually increased with increasing application. The fungal community showed greater sensitivity to biochar addition than bacteria. The study offers novel insights into the impact of biochar on the rhizosphere environment of saline-alkali soils and its potential for soil amelioration.