Soil reclamation induced salinity decline is associated with shifts in bacterial, fungal and protistan communities and higher wheat yield in saline-alkali fields

Soil reclamation is widely practiced in saline–alkali land areas. However, limited research has focused on how reclamation duration regulates soil microbial communities and crop yield via modifying soil environmental conditions. In this study, high-throughput sequencing, ecological network analysis, and soil physicochemical characterization were integrated to investigate variations in soil properties, microbial community composition, and crop yield across saline–alkali fields with different reclamation durations (1, 5, and 10 years). The results showed that prolonged reclamation significantly reduced soil salinity and increased soil nutrient contents as well as wheat yield. The richness of fungi and protists increased with the extension of reclamation durations, whereas bacterial richness exhibited an opposite trend. Network-associated key taxa of bacteria, fungi and protists were significantly correlated with wheat yield, soil salinity, soil organic matter (SOM), total nitrogen (TN), as well as the activities of leucine aminopeptidase (LAP) and β-glucosidase (Glu). Structural equation modeling (SEM) further revealed that soil salinity was associated with soil physicochemical traits, network-associated key taxa and enzyme activities, altered the soil microecological environment, and ultimately affected wheat yield. In conclusion, reclamation durations mitigated soil salinity, which drove the screening of microbial taxa by soil microhabitats and reconstructed the overall microbial community structure, thereby influencing wheat productivity. These findings provide theoretical and technical support for the sustainable reclamation of saline–alkali land, health management of farmland soil, and stable improvement of grain productivity.