Phosphorus-mediated succession of microbial nitrogen, carbon, and sulfur functions in rice-driven saline-alkali soil remediation

Although rice cultivation holds potential for restoring unproductive saline-alkali soils and increasing food pro-duction, the mechanisms underlying the relationship between microbial functions and soil element turnover remain unclear. To clarify this relationship, this study investigated the soil physicochemical properties and microbial functions during remediation in saline-alkali soil by rice cultivation over 2, 4, 6, 8, 11, 12, 20, and 23 years. The results indicated rice cultivation markedly improved soil nutrients, soil nutrient stoichiometry, and soil aggregate stability. Additionally, rice cultivation significantly increased the microbial functions involved in nutrient cycling, such as nitrogen fixation, carbon fixation, methanogenesis, dissimilatory sulfate reduction, and thiosulfate oxidation. However, these nitrogen (N), carbon (C), and sulfur (S) cycle-related functions exhibited a similar increase-peak-decrease successional pattern with the years of remediation, reaching optimal levels when rice was continuously grown for 11-16 years. Furthermore, correlation analysis demonstrated that the succession of soil microbial N, C, and S functions during saline-alkali soil restoration closely related to changes in soil properties, particularly the availability of phosphorus (P). Therefore, we propose to prioritize the manage-ment of P during saline-alkali soil remediation. In conclusion, this study provides a comprehensive under-standing of the microbial N, C, and S functions and soil P in the remediation of saline-alkali soils mediated by rice crop.

Automated summary

This study explored the relationship between microbial functions and soil element turnover during rice cultivation in saline-alkali soil over varying durations. The results showed that rice cultivation greatly improved soil nutrients, soil nutrient stoichiometry, and soil aggregate stability. It also enhanced the microbial functions involved in nutrient cycling, but these functions exhibited a succession pattern with the years of remediation. Correlation analysis indicated that soil microbial functions were closely related to changes in soil properties, especially phosphorus availability. Therefore, managing phosphorus during saline-alkali soil remediation should be prioritized.