Effects of Plastic Shed Cultivation System on the Properties of Red Paddy Soil and Its Management by Reductive Soil Disinfestation

Red paddy soil is widely distributed in the south of China and has become an important production system for food and cash crops. However, the key factors limiting the quality of this soil type under the plastic shed cultivation system and the effective management strategies are still unclear. In the present study, the physicochemical and microbial properties of red paddy soil in a plastic shed (PS-Soil) and open-air (OA-Soil) cultivation systems were compared. Subsequently, reductive soil disinfestation (RSD) and organic fertilizer treatment (OF) were used to improve the soil properties in a representative PS-Soil. Results showed that the physicochemical and microbial properties in PS-Soil were significantly altered compared with those in the nearby OA-Soil, and those differences were primarily dominated by the cultivation system rather than the sampling site. Specifically, the electrical conductivity (EC) and available nutrients (NO3--N, NH4+-N, available K, and available P) contents, as well as the abundances of fungi, potential fungal soil-borne pathogens (F. oxysporum and F. solani), and fungi/bacteria were significantly increased in PS-Soil. In addition, the OF treatment could not effectively improve the above-mentioned soil properties, which was mainly reflected by that soil EC and the abundances of potential fungal soil-borne pathogens were considerably increased in the OF-treated soil. In contrast, soil EC and NO3--N content, the abundances of fungi, F. oxysporum, F. solani, and fungi/bacteria were remarkably decreased by 76%, 99%, 98%, 92%, 73%, and 85%, respectively. Moreover, soil pH, the abundance of bacteria, total microbial activity, metabolic activity, and carbon source utilization were significantly increased in the RSD-treated soil. Collectively, red paddy soil is significantly degraded under the plastic shed cultivation system, and RSD rather than OF can effectively improve the quality of this soil type.