Comprehensive assessments of soil fertility and environmental quality in plastic greenhouse production systems

Abstract

The increasing demand of fruits and vegetables has resulted in the rapid growth of plastic greenhouse production (PGP) systems worldwide. A comprehensive assessment method considering both soil fertility and environmental safety is necessary for the sustainable development of PGP systems. A total of 92 vegetable greenhouses in Jingyang County and 28 fruit greenhouses in Dali County in Shaanxi Province, China, were selected for comparing the changes of soil quality under two cultivation patterns. The soil comprehensive quality index (SQI) in Jingyang (0.53) was significantly higher than that in Dali (0.46) (p < 0.05). A significant correlation was found between the SQI and the soil fertility index (SFI) (p < 0.01), suggesting that the SQI was mainly dependent on the soil fertility level in greenhouses. The primary limiting factors of the SFI in PGP in Jingyang and Dali were low soil organic matter content (19.57 g kg−1) and high electrical conductivity (1303 μS cm−1), respectively, indicating that soil in greenhouses in Jingyang and Dali might experience nutrient deficiencies and soil salinity accumulation problems, respectively. Cd and Hg were main limiting factors of soil environmental index (SEI), especially Hg. The SEI in Dali (0.74) was significantly lower than that in Jingyang (0.81) due to differences in the geo-accumulation indexes of heavy metals in the topsoil in greenhouses. Considering that no significant difference was found in the SFI between two study areas, the SEI is likely responsible for the regional differences in the SQI in PGP. The negative correlation of the SEI with the cultivation ages of plasticulture indicated that heavy metal accumulation problems would be the primary limiting factor of the SQI in the future if greenhouses cannot be managed appropriately. Our study provides data support for soil quality management in PGP systems.