Three-year continuous maize cropping improves saline-alkali soil microenvironment and crop productivity

Introduction The efficient utilization of soda saline-alkali land is of great strategic significance for ensuring China's food security and improving the ecological environment. Cultivating salt-alkali tolerant plants can ameliorate the properties of saline-alkali soil, with rhizosphere microorsganisms playing a crucial role in this process. Methods We conducted a 3-year field experiment in Lamadian, Daqing, China, using high-throughput sequencing to analyze the maize rhizosphere microbial community diversity and its relationships with soil properties, enzyme activities, and plant yield. Results The results showed that pH and total salt (TS) content decreased annually, while the contents of available potassium (AK), available nitrogen, and available phosphorus (AP) and soil polyphenol oxidase (S-PPO), soil urease (S-UE), soil catalase, soil alkaline phosphatase, soil deoxyribonuclease, and soil sucrase (S-SC) enzyme activities increased yearly. The maize yield increased by 8.38% and 2.42% annually. Actinobacteriota, Proteobacteria, Acidobacteriota, and Chloroflexi were the dominant bacterial phyla in the maize rhizosphere soil. Ascomycota, Basidiomycota, and Mortierellomycota were the dominant fungal phyla. Correlation analysis indicated that Blastococcus, Bacillus , and Nocardioides were the key bacteria influencing AK, TS, S-UE, and S-PPO activity. In the fungal community, Tausonia, Mortierella , and Gibellulopsis were the key factors affecting AP, AK, and TS content, as well as S-SC, S-UE, and S-PPO activities. Conclusion Three years of maize cultivation effectively improved the physicochemical properties and enzyme activities of saline-alkali soil and drove the restructuring of the rhizosphere microbial community. Notably, the fungal community structure tended to stabilize after 1 year, whereas bacterial diversity increased annually, revealing their distinct roles in ecological restoration. These results provide a theoretical basis and practical guidance for leveraging crop–microbe interactions to ameliorate saline-alkali land.