Nitrous oxide emissions from tea plantations: A review.

Tea plantations are an important NO source. Fertilizer-induced NO emission factors of tea plantations are much higher than other upland agricultural ecosystems. According to the basic information on characteristics and knowledge of NO emissions from tea plantations around the world, we comprehensively reviewed NO emission characteristics, production process, influencing factors, and reduction measures from tea plantations. The global means of ambient NO emission and NO emission stimulated by nitrogen fertilizer application from tea plantations were (2.68±2.92) kg N·hm and (11.29±9.45) kg N·hm, respectively. The fertilizer-induced NO emission factor in tea plantations (2.2%±2.1%) was much higher than the IPCC-estimated NO emission factor for agricultural land (1%). NO emission from tea plantation soil (a typical acid soil) were mainly produced during nitrification and denitrification, with denitrification being dominant. NO emission from tea plantations were significantly related to the amount of fertilizer application. Other factors, such as fertilizer type, could also affect soil NO emissions in tea plantations. The main reduction methods of NO emission from tea plantations included optimizing the amount and type of fertilizer, amending biochar, and rationally using nitrification inhibitors. In future, we should strengthen observations of soil NO emission from tea plantations at both temporal and spatial scales, combine lab incubation and field studies to elucidate the mechanisms underling tea plantation soil NO emissions, and use a data-model fusion approach to reduce uncertainties in the estimation of global NO emission. These would provide theoretical support and practical guidance for reasonable NO emission reduction in tea plantations.