ABSTRACT Phytoremediation of saline‐alkali soils has emerged as a key strategy to boost agricultural output and mitigate food security challenges. Identifying plants for biomass production and soil recovery is vital for marginal land sustainability, and perennial switchgrass ( Panicum virgatum L.) is preferred for its broad adaptability, stress tolerance, high yield and good quality. In this study, we evaluated switchgrass biomass allocation and its effects on soil physicochemical properties and soil microbial community structure in severely saline‐alkali coastal soil over a three‐year period. The results showed that after 3 years of cultivation, switchgrass above‐ and below‐ground biomass increased from 1.86 to 12.64 t ha −1 and 0.08 to 7.17 t ha −1 , respectively. These plant responses were tightly coupled with rapid soil improvement, including a 2.54‐fold increase in large water‐stable aggregates (0.25–2 mm), a 95.7% reduction in water‐soluble Na + , a 4.69% reduction in soil pH and a 21.32‐fold reduction in electrical conductivity. Soil fertility was concurrently enhanced, as indicated by increased soil organic matter content and cation exchange capacity. Microbial community analyses revealed pronounced domain‐specific response strategies. Bacterial communities maintained a stable core structure while undergoing functional reorganization toward enhanced organic matter decomposition and nutrient cycling. In contrast, archaeal and fungi communities exhibited stronger niche‐driven turnover, including a shift from methanogenesis toward potential nitrification in archaea and increased abundance of arbuscular mycorrhizal and saprotrophic fungi. These microbial responses were strongly regulated by shifts in key soil environmental factors, including reduced salinity and pH (electrical conductivity and total water‐soluble salts) and increased soil organic matter and cation exchange capacity. Overall, switchgrass cultivation triggered a coupled plant–soil‐microbe feedback that sustained biomass production and accelerated the recovery of saline‐alkali soils, highlighting its potential for bioenergy production and ecological restoration in coastal saline‐alkali regions.
Chang et al. (Mon,) studied this question.