RESUMO
In recent years, the area of tea fields in China has expanded. The application rate of nitrogen fertilizer is usually high in tea fields, which causes high N2O emissions. Tea fields are important sources of N2O emissions; thus, it is necessary to research N2O emission reduction in tea fields. A three-year field study was conducted to investigate soil N2O emissions and influencing factors under different fertilization measurements in a typical tea field in a subtropical hilly region of China. Three treatments-conventional fertilization, deep application of nitrogen fertilizer, and intercropping with clover-were studied to measure the soil N2O fluxes and the related soil and environmental properties. The results showed that the subtropical hilly tea field had high N2O emissions, and the cumulative annual emissions of N2O-N were as high as 5.1-10.1 kg·hm-2. The N2O emissions occurred mainly in spring and summer. When the soil temperature was lower than 15â, the N2O flux shown mainly a positive correlation with the soil temperature. However, when the soil temperature was higher than 15â, the positive correlation was mainly with the soil water, soil NH4+-N, and NO3--N contents. Compared with conventional fertilization, the intercropping of white clover did not significantly reduce N2O emissions, although deep application of fertilizer increased annual N2O emissions when the rainfall was high. Neither intercropping of white clover or deep application of fertilizer affected the tea yield or the yield-scaled N2O emissions compared with conventional fertilization. Our study indicates that both intercropping of white clover and deep application of fertilization without reducing the nitrogen application rate did not reduce the soil N2O emissions in subtropical tea fields. Further studies are needed to determine the effects of deep fertilization application combined with a reduction in the nitrogen application rate on N2O emissions from tea fields.
