Effects of Irrigation Strategy and Plastic Film Mulching on Soil N2O Emissions and Fruit Yields of Greenhouse Tomato

Agriculture is a major source of global greenhouse gas emissions. Approximately 1/3 of vegetables in China are produced in greenhouses. However, the effects of different irrigation strategies and plastic film (PF) mulching combinations on N2O emissions and tomato fruit yields in greenhouses are unclear. The aims of this study were to explore the effects of micro-sprinkler irrigation under plastic film (MSPF), drip irrigation under plastic film (DIPF) and micro-sprinkler irrigation (MSI) on the soil nutrients, enzyme activity, nirS-type denitrifying bacterial community, N2O emissions and fruit yields of tomato. The results showed that MSPF could improve the uniformity of soil water distribution and surface (0–40 cm) soil water content. Film mulching could increase soil temperature at depths of 5–25 cm. Both MSPF and DIPF increased microbial nitrogen, promoted the activity of rhizosphere soil urease and leucine aminopeptidase, changed the community of denitrifying bacteria, accelerated the turnover of soil nutrients and improved yield and water use efficiency. PF mulching had a greater impact on the nirS-type denitrifying bacterial community when compared to irrigation strategy. We conclude that MSPF can be used to configure commercially available installation and operation. The comprehensive benefit of MSPF treatment is that it is more profitable than that of DIPF.