Phase changes of continuous cropping obstacles in strawberry (Fragaria x ananassa Duch.) production

Soil ecology plays an important role in the growth and health of plants. Research suggests that long-term monocropping may lead to soil ecological disorders. In this study, we aimed to understand the reasons for the decrease in plant productivity stemming from long-term monoculture cropping. Greenhouse studies were conducted to determine the cause of continuous cropping (CC) obstacles in soils under 12 years of continuous strawberry (Fragaria x ananassa Duch.) production. The data suggested that CC led to three phases of changes in abiotic and biotic soil factors. In phase I (CC for 2-6 years), significant changes were observed only in soil physicochemical properties, such as the pH, total nitrogen (TN), ammonium nitrogen (NH4+-N), available phosphorus (AP), available potassium (AK) and soil organic matter (SOM), which obviously changed from the second year to the sixth year. In phase II (CC for 6-8 years), two biotic factors, key fungi such as Fusarium, Humicola and Arthrobotrys and soil nematodes, i.e., populations and communities of nematodes, started to change significantly in terms of their abundance. In phase III (CC for 8 years), the accumulation of phenolic acids, i.e., p-hydroxybenzoic acid (p-HBA), ferulic acid (FA), p-coumaric acid (p-CA) and cinnamic acid (CA), significantly inhibited crop growth, and the abundance of key bacteria, including Bacillus, Sphingomonas and Sphingopyxis, started to change significantly from the eighth CC year. The results in this study provide useful information for solving CC obstacles in strawberry production.