Nitrous oxide emissions from tea plantations: A review.

Tea plantations are an important N ₂ O source. Fertilizer-induced N ₂ O emission factors of tea plantations are much higher than other upland agricultural ecosystems. According to the basic information on characteristics and knowledge of N ₂ O emissions from tea plantations around the world, we comprehensively reviewed N ₂ O emission characteristics, production process, influencing factors, and reduction measures from tea plantations. The global means of ambient N ₂ O emission and N ₂ O emission stimulated by nitrogen fertilizer application from tea plantations were (2.68±2.92) kg N·hm ^-2 and (11.29±9.45) kg N·hm ^-2 , respectively. The fertilizer-induced N ₂ O emission factor in tea plantations (2.2%±2.1%) was much higher than the IPCC-estimated N ₂ O emission factor for agricultural land (1%). N ₂ O emission from tea plantation soil (a typical acid soil) were mainly produced during nitrification and denitrification, with denitrification being dominant. N ₂ O emission from tea plantations were significantly related to the amount of fertilizer application. Other factors, such as fertilizer type, could also affect soil N ₂ O emissions in tea plantations. The main reduction methods of N ₂ O emission from tea plantations included optimizing the amount and type of fertilizer, amending biochar, and rationally using nitrification inhibitors. In future, we should strengthen in-situ observations of soil N ₂ O emission from tea plantations at both temporal and spatial scales, combine lab incubation and field studies to elucidate the mechanisms underling tea plantation soil N ₂ O emissions, and use a data-model fusion approach to reduce uncertainties in the estimation of global N ₂ O emission. These would provide theoretical support and practical guidance for reasonable N ₂ O emission reduction in tea plantations.