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| Effects of soil oxygen concentrations on the N2 and N2O production in soil profiles of a maize-wheat rotation cropland |
| Received:April 20, 2022 |
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| KeyWord:soil profile;denitrification;N2;N2O;O2 concentration;NO3--N concentration |
| Author Name | Affiliation | E-mail | | GAO Yongxin | School of Ecology and Environment, Inner Mongolia University, Huhehot 010021, China
State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China | | | PAN Zhanlei | 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 | | | WANG Rui | State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China | wangrui@mail.iap.ac.cn | | WANG Lin | State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China | | | YAO Zhisheng | State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China | | | ZHENG Xunhua | 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 | | | MEI Baoling | School of Ecology and Environment, Inner Mongolia University, Huhehot 010021, China | | | ZHANG Chong | College of Tropical Crops, Hainan University, Haikou 570228, China | | | JU Xiao-tang | College of Tropical Crops, Hainan University, Haikou 570228, China | |
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| Abstract: |
| Denitrification is a vital process for excess nitrate removal from soil profile of intensive croplands. However, the quantification of dinitrogen(N2)production via denitrification in soil profiles is very difficult, especially how changes in soil oxygen(O2)concentrations at different depths affect soil N2 production remains unclear. Here, we used the gas-flow-soil-core technique to quantify N2 and N2O production from intact soil cores collected at three different depths within 0-2 m soil profiles of a maize -wheat rotation cropland in the North China Plain. Based on the field observations of soil O2 concentration and temperature in soil profiles during the maize growing season, different O2 levels(15.0%, 12.0%, 2.5%, and 0)and incubation temperatures(26℃ and 20℃)were set. Our results showed that the production of N2 and N2O decreased with soil depth, regardless of soil O2 concentration. The soil N2 production under aerobic conditions (2.5%-15.0% O2)ranged from 5.3-7.1 μg·h-1·kg-1(0.2 m)and 0.5-2.3 μg·h-1·kg-1(0.5 m and 2.0 m), which were 93.0%~93.7% lower than that under anaerobiosis. Similarly, the aerobic N2O production were 1.1 μg·h-1·kg-1(0.2 m)and <0.2 μg·h-1·kg-1(0.5 m and 2.0 m), approximately 84.0%-99.1% lower than that under anaerobiosis. The field-measured O2 concentrations in soil profiles were >2.5%(0.2 m and 0.5 m)and >14.0%(2.0 m), indicating that the anaerobic observation would lead to overestimation of N2 and N2O production in the field soil conditions. Moreover, anaerobiosis significantly increased the N2O/(N2O + N2)ratio in the deep soil, probably because of the limited reduction of N2O to N2 under lower carbon availability. Based on observations under aerobic conditions, the denitrification(N2O+ N2)production in the 0-2.0 m soil profile was estimated to be 219 kg·hm-2 for the maize growing season(120 days). Our results showed that the studied soil had a strong ability to remove the NO3--N accumulated in the profile, which greatly reduced the risk of NO3--N leaching from the vadose zone to groundwater. |
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