[Effects of Tomato Planting Years on Soil Physical and Chemical Properties and Microbial Communities]

Long-term continuous cropping of facility soils could influence soil properties; however, the differences in soil properties among different continuous cropping years are still not well understood. The objective of this study was to explore the effects of continuous cropping years of tomato on the physical and chemical properties and biological characteristics of facility soil. Conventional analysis, high-throughput sequencing, and other methods were used to examine the soil physicochemical properties, soil microbial community diversity, and enzyme activities in facility soil after continuous tomato cropping for 1-3 years, 5-7 years, and more than 10 years. As the continuous tomato cropping years increased, soil bulk density and pH decreased; soil maximal water holding capacity increased; and organic matter, total nitrogen, and total phosphorus accumulated. As continuous cropping years increased, the total salt and EC value decreased with continuous cropping for 5-7 years and increased from 5-7 years to more than 10 years continuous cropping and showed a trend of secondary soil salinization. There was a significant increase in alkaline phosphatase for 1-3 years to 5-7 years continuous tomato cropping. There were significant differences in fungal community abundance among different cropping years. The Simpson index and Shannon index of fungi showed a trend of increasing first and then decreasing with the extension of continuous cropping years and reached the maximum value at 5 years of continuous cropping. The Chao1 index decreased continuously following the cropping years. As continuous cropping years increased, Streptomyces became the dominant bacteria, and Aspergillus and Pseudaleuria became the dominant fungi. The key factors affected by continuous cropping years were available potassium and available nitrogen based on the redundancy analysis. The results of this study lay the foundation for future research on the influence of continuous cropping years on the health of facility soil.