Fertilizer nitrogen loss via N-2 emission from calcareous soil following basal urea application of winter wheat
Zhang Yukun; Wang Rui; Pan Zhanlei; Liu Yan; Zheng Xunhua; Ju Xiaotang; Zhang Chong; Butterbach-Bahl, K.; Huang Binxiang
Atmospheric and Oceanic Science Letters 12(2): 91-97
ISSN/ISBN: 1674-2834 DOI: 10.1080/16742834.2019.1568817
The ratio of nitrous oxide (N2O) to N2O plus nitrogen gas (N-2) emitted from soils (N2O/(N2O+N-2)) is regarded as a key parameter for estimating fertilizer nitrogen (N) loss via N-2 emission at local, regional or global scales. However, reliable measurement of soil N-2 emissions is still difficult in fertilized soil-crop systems. In this study, the N loss via N-2 emission following basal urea application (with a dose of 150 kg N ha(-1)) to a calcareous soil cultivated with winter wheat was quantified using the helium-based gas-flow-soil-core technique. Emissions of N-2 and N2O from sampled fresh soils were measured under simulated field soil temperature and oxygen conditions. Our observation performed on the first day after irrigation and rainfall events showed the highest N-2 and N2O emissions, which amounted to approximately 11.8 and 3.8 g N h(-1) kg(-1) dry soil, corresponding to 3304 and 1064 g N m(-2)h(-1), respectively. The N2O/(N2O+N-2) molar ratios within about 10days following fertilization ranged from 0.07 to 0.25, which were much larger than those at the other time. During the one-month experimental period, the urea-N loss via emissions of N-2, N2O, and N-2+N2O was 1.6%, 0.6%, and 2.2%, respectively. Our study confirms that the widely applied acetylene-inhibition method substantially underestimates fertilizer N losses via N-2 emissions from calcareous soils cultivated with winter wheat.