ABSTRACT Biochar application is increasingly recognized for its ability to mitigate greenhouse gas emissions and enhance nitrogen retention in soils. However, its effects on nitrogen‐cycling microbial communities in saline‐sodic soil remain poorly understood. We conducted a two‐year field experiment under oat cultivation with four biochar application rates (0, 10, 30, and 50 t ha −1 ). Quantitative PCR and amplicon sequencing of key N‐cycling genes ( nifH , amoA ‐AOA, amoA ‐AOB, nirK , nirS , and nosZ ) were employed to assess changes in microbial community abundance and structure. Short‐term biochar application significantly decreased nifH ‐ and AOB‐related abundances, indicating initial inhibition of nitrogen fixation and ammonia oxidation. Biochar application also significantly reduced the Chao1 diversity of nifH ‐ and nirS ‐related taxa, while a higher application rate (50 t ha −1 ) further lowered the Shannon diversity of nirS ‐ and nosZ ‐related communities. AOB were more sensitive than AOA, showing stronger abundance reductions and community shifts. LEfSe analysis revealed persistent compositional changes only in nifH ‐ and nosZ ‐related groups, with nifH ‐related taxa enriched under B10 and nosZ ‐related taxa under B30 and B50 treatments. Mantel tests identified soil CO 3 2− , Cl − , and Na + as major environmental drivers of N‐cycling microbial variation. Overall, biochar application exerted time‐ and dose‐dependent effects on N‐cycling microbial communities in saline‐sodic soil. The gradual stabilization of microbial communities highlights their ecological resilience through microbial adaptation, rather than a return to the original state, and suggests that biochar‐induced shifts may ultimately influence nitrogen fixation and N 2 O mitigation in salt‐affected agroecosystems.
Liu et al. (Sun,) studied this question.
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