Articles | Volume 12, issue 20
Research article
16 Oct 2015
Research article |  | 16 Oct 2015

Organically fertilized tea plantation stimulates N2O emissions and lowers NO fluxes in subtropical China

Z. Yao, Y. Wei, C. Liu, X. Zheng, and B. Xie

Abstract. Tea plantations are rapidly expanding in China and other countries in the tropical and subtropical zones, but so far there are very few studies including direct measurements of nitrogenous gas fluxes from tea plantations. On the basis of 2-year field measurements from 2012 to 2014, we provided an insight into the assessment of annual nitrous oxide (N2O) and nitric oxide (NO) fluxes from Chinese subtropical tea plantations under three practices of conventional urea application, alternative oilcake incorporation and no nitrogen fertilization. Clearly, the N2O and NO fluxes exhibited large intra- and inter-annual variations, and furthermore, their temporal variability could be well described by a combination of soil environmental factors including soil mineral N, water-filled pore space and temperature, based on a revised "hole-in-the-pipe" model. Averaged over a 2-year study, annual background N2O and NO emissions were approximately 4.0 and 1.6 kg N ha−1 yr−1, respectively. Compared to no nitrogen fertilization, both urea and oilcake application significantly stimulated annual N2O and NO emissions, amounting to 14.4–32.7 kg N2O–N ha−1 yr−1 and at least 12.3–19.4 kg NO–N ha−1 yr−1, respectively. In comparison with conventional urea treatment, on average, the application of organic fertilizer significantly increased N2O emission by 71 % but decreased NO emission by 22 %. Although the magnitude of N2O and NO fluxes was substantially influenced by the source of N, the annual direct emission factors of N fertilizer were estimated to be 2.8–5.9, 2.7–4.0 and 6.8–9.1 % for N2O, NO and N2O+NO, respectively, which are significantly higher than those defaults for global upland croplands. This indicated that the rarely determined N2O and NO formation appeared to be a significant pathway in the nitrogen cycle of tea plantations, which are a potential source of national nitrogenous gases inventory.

Final-revised paper