Effects of N Fertilizer Application on Soil N2O Emissions and CH4 Uptake: A Two-Year Study in an Apple Orchard in Eastern China
Baohua Xie,
Jiangxin Gu,
Junbao Yu,
Guangxuan Han,
Xunhua Zheng,
Yu Xu,
Haitao Lin
Affiliations
Baohua Xie
Key Laboratory of Coastal Zone Environmental Processes and Ecological Remediation, CAS, Shandong Provincial Key Laboratory of Coastal Environmental Processes, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, China
Jiangxin Gu
College of Natural Resources and Environment, Northwest A&F University, Yangling 712100, China
Junbao Yu
Key Laboratory of Coastal Zone Environmental Processes and Ecological Remediation, CAS, Shandong Provincial Key Laboratory of Coastal Environmental Processes, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, China
Guangxuan Han
Key Laboratory of Coastal Zone Environmental Processes and Ecological Remediation, CAS, Shandong Provincial Key Laboratory of Coastal Environmental Processes, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, China
Xunhua Zheng
State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
Yu Xu
Agricultural Resources and Environment Institute, Shandong Academy of Agricultural Sciences, Jinan 250100, China
Haitao Lin
Agricultural Resources and Environment Institute, Shandong Academy of Agricultural Sciences, Jinan 250100, China
Land use changes from cropland to orchards in Eastern China have raised serious concerns about the regional nitrogen (N) cycle and greenhouse gas balance. We measured soil nitrous oxide (N2O) emissions and methane (CH4) uptake using manual static chambers in an apple orchard. The primary aims were to assess the effect of N fertilizer application on gas fluxes and quantify the site-specific N2O emission factor (EFd). Field experiments were arranged in a randomized block design with three N input rates (0, 800 and 2600/2000 kg N ha−1 year−1). We found that orchard soils were a negligible CH4 sink (−1.1 to −0.4 kg C ha−1 year−1). Annual N2O emissions responded positively to N input rates, ranging from 34.1 to 60.3 kg N ha−1 year−1. EFd ranged from 1.00% to 1.65% with a mean of 1.34%. The extremely large background emissions of N2O (34.1–34.3 kg N ha−1 year−1) most likely originated from nitrate accumulation in the soil profile because of historical overuse of N fertilizer. We conclude that (1) site-specific EFd is suitable for assessing regional direct N2O emissions from upland orchards; and (2) conventional fertilization regimes must be avoided, and reduced N input rates are recommended in the study region.
