Time-lagged induction of N2O emission and its trade-off with NO emission from a nitrogen fertilized andisol
2007
Ding, W.(National Inst. for Agro-Environmental Sciences, Tsukuba, Ibaraki (Japan)) | Yagi, K. | Akiyama, H. | Sudo, S. | Nishimaru, S.
To understand the influence of basal application of N fertilizer on nitrification potential and N2O and NO emissions, four soil samples were collected from an upland Andisol field just before (sample 1) and 4 (sample 2), 36 (sample 3) and 72 (sample 4) days after the basal application of N fertilizer during the Chinese cabbage growing season from 12 September to 30 November 2005. The potentials of N2O production and nitrification of the soils were determined using a sup(15)N tracer technique and the soils were incubated for 25 days at 25 deg C and 60% water-filled pore space (WFPS). The results revealed that as much as 84-97% N2O and almost all NO were produced by nitrification. The sup(15)N2O emission peak occurred approximately 350 h after the beginning of incubation for samples 1 and 2, but just 48 h later in samples 3 and 4. Total sup(15)N2O emission during the 25-day incubation of samples 3 and 4 ranged from 190 to 198 microg N/kg soil, which was significantly higher than the 99-108 microg N/kg soil recorded in samples 1 and 2. Basal application of N fertilizer did not immediately increase the nitrification potential and the ratio of N2O to N added, but did dramatically increase the nitrification potential and the ratio of N2O to N added as (sup(15)NH4)2SO4 36-72 days after the basal N fertilizer was added. In contrast, NO emission was negatively correlated with nitrification potential and total N2O emission. As a result, a trade-off relationship between total NO and N2O emissions was identified. The results indicated that there was a time-lagged induction of the change of N turnover in the soil, which was possibly caused by slow population growth of the nitrifiers and/or a slow shift in the microbial community in the soil.
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