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| Nitrous oxide emissions and controlling factors of tea plantations in China |
| Received:February 08, 2020 |
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| KeyWord:tea plantation;greenhouse gas;nitrous oxide;fertilized cropland;emission factor |
| Author Name | Affiliation | | YAO Zhi-sheng | State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China | | WANG Yan | State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China | | WANG Rui | State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China | | LIU Chun-yan | State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China | | ZHENG Xun-hua | State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China |
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| Abstract: |
| Tea, as a popular beverage, plays an important role for local cultural and economic developments in China, but its cultivation with high amounts of nitrogen(N)application results in environmental degradation, such as soil acidification and high emissions of greenhouse gas nitrous oxide (N2O). So far, however, our understanding and quantification of total N2O emissions from tea plantations in China remain unclear, though several observations have been conducted at a site-level. Based on 70 datasets (including 45 and 25 datasets for fertilized and unfertilized treatments, respectively)extracted from in-situ field studies, we performed a comprehensive synthesis to characterize and quantify annual N2O emissions and direct emission factors(EFds)in dependence of environmental factors(i.e. climate and soil properties)and management practices across Chinese tea plantations. Results showed that mean annual N2O emissions across tea plantations in China were estimated to be 9.55 kg N·hm-2·a-1(with 95% confidence intervals of 7.54~11.9 kg N·hm-2·a-1), higher than those in Chinese major cereal croplands. Also, the analysis yields a mean EFd for tea in China equaled to 1.92%(with 95% confidence intervals of 1.49%~2.39%), being double as high as the IPCC default value of 1% for global crops. Across all the datasets, a regression analysis showed that N application rate was key factor driving annual N2O emissions, both exerting a significant positive linear correlation. While the EFd was mainly regulated by the combined effects of soil C/N ratio and clay content, i.e. EFd being strongly negatively correlated with soil C/N ratio and clay content. On basis of the current estimated mean EFd for tea, the tea planting area, and the N fertilizer application rate, total N2O emissions from Chinese tea plantations in 2018 were estimated to be approximately 28 Gg N·a-1, contributing up to 15% of total cropland N2O emissions. This suggested that although the area of tea was small(only accounting for <2% of Chinese total cropland area), tea plantations were hotspots of N2O emissions in the crop production sector. To address high emission characteristics of tea plantations, our results also revealed that applying the combination of synthetic and organic N fertilization, controlled-release fertilizers or biochar amendment to Chinese tea plantations was a promising management strategy for increasing N-use efficiency while effectively reducing soil N2O emissions. |
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