Abstract: 【Objective】 Strawberries are typically planted annually with annual disinfection treatments to suppress pests and diseases. In contrast, strawberries are harvested several years after planting in Huize, Yunnan, China, fruit can be harvested for 3-5 years after planting. This strategy results in low carbon emissions and significantly reduces the labor input and the cost of nursery supplies, chemical fumigants, and plastic film. Although farmers could harvest strawberries multiple years after planting, strawberry yield and profits decreases since the third year, and the production becomes unprofitable since the fifth year. Soil degradation is suspected to be the reason for the inability to sustain stable production. We have insufficient knowledge of the factors affecting the soil degradation in multi-year harvesting (MYH) areas. 【Methods】 We examined soil nutrient traits and the microbial structure of four strawberry fields following MYH in this area, the SOM (Soil organic matter) content, pH, and key mineral nutrient contents of strawberry (N, P, K, Ca, Mg, Cu, Zn, and Mo) were assessed. The soil microbial community was analyzed by high-throughput amplicon sequencing based on Illumina MiSeq PE300 platform. The soil microbial functions were predicted to determine the effect of MYH of strawberries on soil microbial communities. The microbial function focusing on C-cycling and N-cycling processes were assessed to determine the soil productivity tendency. 【Results】Our results indicated that MYH resulted in significant soil acidification, salinization, and organic matter deficiency. The average soil pH was 5.58±0.67 in the first year and decreased to 4.35±0.53, 3.57±0.28, and 2.98±0.04 in the second, third, and fourth years, respectively. The average SOM content was 0.66±0.14% in the first year and 0.27±0.03% in the fourth year (a 25.6% decrease per year). The average soil EC was 328.5±113.3 in the first year and 923.7±158 in the fourth year (a 41.1% increase per year). The Ca content showed a generally decreasing trend at most sites, and the lowest Ca content occurred in the fourth harvesting year of JC1 (0.878 g/kg, 74.4% lower than in the first harvesting year). Our results demonstrated that MYH significantly affected the soil microbial community. The Chao1 richness, Shannon, and ACE indices of the bacterial communities in soil differed significantly among the harvesting years. The Chao1 richness decreased significantly by 13.6% from the first to the second harvesting year, 38.2% to the third harvesting year, and 41.8% to the fourth harvesting year. The greatest decline in the Chao1 richness index was observed in the fourth harvesting year of JC1 (52.2%) and the third harvesting year of JC2 (52.5%). The Chao1 richness and ACE indices for fungal diversity differed among the harvesting years at all sites except XJ. The ACE index decreased by 28.7% from the first to the second year of DB1, 25.0% from the first to the second year of JC2, and 31.7% from the second to the third year of JC1. The fungal diversity of XJ was lower than at the other three sites. The average ACE of the XJ samples was 578.7, which was 37.2% lower than that of DB1, 25.5% lower than that of JC1, and 33.2% lower than that of JC2. The relationship between microbial community and environmental variables was analyzed by RDA. RDA1 (34.33%) and RDA2 (21.96 %) explained 56.29% of the total variation in bacterial community structure. For fungi, RDA1 (26.21%) and RDA2 (12.98 %) explained 39.19% of the total variation. SOM, pH, and EC were the dominant contributors to the variation of bacterial community, accounting for 59.8%, 58.9%, and 51.8%, respectively. Soil EC and SOM were the most important contributors to the variation of fungal community, accounting for 83.3% and 82.7%, respectively. FAPROTAX was utilized to determine the functional effects of MYH on the bacterial community. The relative abundance of N-cycling processes related bacteria showed a decreasing trend. Correlation analysis showed that most C-cycling and N-cycling processes were significantly positively correlated with the SOM content and negatively correlated with EC, whereas most C-cycling processes was significantly positively correlated with pH. The FUNGuild analysis showed a significantly decreasing trend for that relative abundance of Symbiotroph fungi and arbuscular mycorrhizal fungi (AMF), and the relative abundance of Fusarium, the main pathotroph of strawberry, showed a significantly increasing trend. 【Conclusion】 Our results indicated that MYH of strawberries resulted in significant soil acidification, salinization and SOM deficiency, and shaped microbial community structures as well. Of both bacteria and fungi, the community diversity decreased by year, while symbiotroph fungi and AMF showed a significantly decreasing trend in the MYH treatment. Soil microbial function prediction suggested that MYH reduced the N cycles related bacterial functions, while most C-cycling and N-cycling processes was positively correlated with SOM, and negatively correlated with EC. The MYH of strawberries showed a significant negative impact not only on soil physicochemical properties but also on microbial community and function. Thus, for this multiyear harvesting strategy of strawberries, maintaining soil physicochemical properties and soil microbial structure and function is key problem to be solved for sustainable development.
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