氧气浓度对小麦-玉米轮作农田土壤剖面N_(2)和N_(2)O产生的影响  

Effects of soil oxygen concentrations on the N_(2) and N_(2)O production in soil profiles of a maize-wheat rotation cropland

作　　者：高永欣 潘占磊 王睿[2] 王琳 姚志生[2] 郑循华[2,3] 梅宝玲 张翀 巨晓棠 GAO Yongxin;PAN Zhanlei;WANG Rui;WANG Lin;YAO Zhisheng;ZHENG Xunhua;MEI Baoling;ZHANG Chong;JU Xiaotang(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;College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China;College of Tropical Crops,Hainan University,Haikou 570228,China)

机构地区：[1]内蒙古大学生态与环境学院,呼和浩特010021 [2]中国科学院大气物理研究所大气边界层物理和大气化学国家重点实验室,北京100029 [3]中国科学院大学地球与行星科学学院,北京100049 [4]海南大学热带作物学院,海口570228

出　　处：《农业环境科学学报》2023年第1期227-236,共10页Journal of Agro-Environment Science

基　　金：国家自然科学基金项目(41877333,41830751);国家重点研发专项(2017YFD0200100)。

摘　　要：反硝化过程是集约化农田土壤剖面硝态氮(NO_(3)^(-)-N)去除的重要途径。但对土壤剖面反硝化氮气(N_(2))产生速率的准确定量很难,尤其不同深度的土壤氧气(O_(2))浓度状况如何影响土壤N_(2)的产生仍不清楚。本研究依托集约化管理的冬小麦-夏玉米轮作田间长期定位试验(始于2006年),采集传统施肥处理0~2.5 m剖面的原状土柱,并基于在玉米生长季田间原位观测的不同深度土壤O_(2)浓度和温度状况,设置不同O_(2)浓度水平(15.0%、12.0%、2.5%和0)和培养温度(26℃和20℃),采用氦培养-直接测定N_(2)法测定3个不同深度(0~0.2、0.5~0.7 m和2.0~2.2 m)土壤N_(2)O和N_(2)产生速率。结果显示:无论是有氧还是无氧条件,土壤剖面N_(2)和N_(2)O的产生均表现为表层高于深层;有氧条件下(2.5%~15.0%O_(2))土壤N_(2)产生速率(以N计)为5.3~7.1μg·h^(-1)·kg^(-1)(0.2m)和0.5~2.3μg·h^(-1)·kg^(-1)(0.5 m和2.0 m),显著低于无氧下速率的93.0%~93.7%。同样地,有氧条件下N_(2)O产生速率(以N计)为1.1μg·h^(-1)·kg^(-1)(0.2 m)和<0.2μg·h^(-1)·kg^(-1)(0.5 m和2.0 m),显著低于无氧条件下速率的84.0%~99.1%。原位观测的土壤O_(2)浓度>2.5%(0.2 m和0.5 m)和>14.0%(2m),表明在无氧条件下的观测会高估土壤真实条件下的N_(2)和N_(2)O产生速率。无氧显著增加深层土壤的N_(2)O/(N_(2)O+N_(2))值,这可能是由于深层土壤的碳更加缺乏,不利于N_(2)O被进一步还原。基于有氧条件下观测的N_(2)和N_(2)O产生速率,估算得到玉米生长季(按120d计)剖面0~2.0 m土体的反硝化(N_(2)+N_(2)O)损失量可达219 kg·hm^(-2),表明土壤对其剖面累积的NO_(3)^(-)-N具有很强的脱氮能力,从而极大地减少了包气带累积NO_(3)^(-)-N进一步向地下水迁移的风险。Denitrification is a vital process for excess nitrate removal from soil profile of intensive croplands.However,the quantification of dinitrogen(N_(2)) production via denitrification in soil profiles is very difficult,especially how changes in soil oxygen(O_(2)) concentrations at different depths affect soil N_(2)production remains unclear.Here,we used the gas-flow-soil-core technique to quantify N_(2)and N_(2)O 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 O_(2)concentration and temperature in soil profiles during the maize growing season,different O_(2)levels(15.0%,12.0%,2.5%,and 0) and incubation temperatures(26 ℃and 20 ℃) were set.Our results showed that the production of N_(2)and N_(2)O decreased with soil depth,regardless of soil O_(2)concentration.The soil N_(2)production under aerobic conditions(2.5%-15.0% O_(2)) ranged from 5.3-7.1 μg·-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 N_(2)O 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 O_(2)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 N_(2)and N_(2)O production in the field soil conditions.Moreover,anaerobiosis significantly increased the N_(2)O(N_(2)O+N_(2)) ratio in the deep soil,probably because of the limited reduction of N_(2)O to N_(2)under lower carbon availability.Based on observations under aerobic conditions,the denitrification(N_(2)O+N_(2))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 NO_(3)^(-)-N accumulated in the profi

关 键 词：土壤剖面 反硝化 N_(2) N_(2)O O_(2)浓度 NO_(3)^(-)-N含量 

分 类 号：S512.11[农业科学—作物学] S513