Effects of Different Remediation Measures on Soil Physicochemical Properties and Rhizosphere Microbial Communities in Continuous Cropping Apple Nurseries

Purpose This study aimed to investigate the regulatory effects of different remediation measures on soil physicochemical properties and rhizosphere microbial communities in apple seedling nurseries with continuous cropping obstacles, thereby providing a theoretical basis for the scientific management of continuous cropping obstacles in orchards.

Methods A randomized block experiment was conducted with five treatments: conventional organic fertilizer (CK), chloropicrin fumigation (T₁), lime nitrogen fumigation combined with a composite microbial agent (T₂), sulfur amendment combined with an acid-tolerant microbial agent (T₃), and deep tillage combined with a high-intensity microbial agent (T₄). A comprehensive analysis was conducted by combining the determination of soil physicochemical properties with high-throughput sequencing of the soil microbial communities.

Results Compared with CK, the soil pH in all treatments significantly decreased (P<0.05), with T₂ and T₃ decreasing by 3.53% and 3.89%, respectively; the contents of soil available phosphorus (12.47%-50.74%) and available potassium (48.42%-67.95%) were significantly increased. The alkali-hydrolyzable nitrogen contents in the T₂ and T₃ treatments significantly increased by 30.17% and 22.94%, respectively, while T₃ and T₄ significantly promoted soil organic matter accumulation. All remediation measures significantly increased bacterial community richness and diversity, while suppressing fungal community diversity and the abundance of potential pathogenic fungi. Notably, the T₂ treatment exhibited a strong enrichment effect on functional groups related to nutrient transformation and disease suppression, and significantly reduced the relative abundance of Fusarium. Correlation analysis indicated that available potassium and total potassium were closely associated with bacterial community structure variation, whereas alkali-hydrolyzable nitrogen and available phosphorus played important roles in regulating fungal community structure.

Conclusion Different remediation measures influence rhizosphere microbial community structure and composition by improving soil nutrient conditions, thereby contributing to the improvement of soil ecological environments of continuous cropping obstacle soils.