Obstacles in continuous cropping: Mechanisms and control measures

With the increase in intensive cultivation and long-term monoculture cropping, problems caused by continuous cropping (CC) have become increasingly prominent in the forms of replant diseases, soil sickness, and yield penalties. Such CC obstacles are a concern which frequently occur in modern agro-ecosystems and severely hamper normal growth, development, and quality of crop plants. In this review, we analyze studies from 2010 to 2021 on the effects of CC on crop plants and soil conditions constituting CC obstacles. The CC has significant adverse effects on plant growth and development, which mainly manifest in weaker photosynthesis, retarded growth, reduced resistance, and decreased yield and harvest quality. The causes of CC obstacles vary markedly among different crops, and the underlying mechanism depend on soil characteristics. The effects of the soil environment, crop physiological resistance, and auto-toxicity on CC obstacles are summarized. Considering the strategies to reduce the impacts of CC obstacles, the main prevention and control methods for CC obstacles are discussed, including intercropping or rotation, organic fertilization, fallow, biological control, and soil disinfection approaches. In addition, we discuss problems and proposed prospects for future research to improve prevention measures and control of CC obstacles. This review provides reference and guidance for solving this fundamental agronomic production problem.