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| Titel |
Responses of N2O and CH4 fluxes to fertilizer nitrogen addition rates in an irrigated wheat-maize cropping system in northern China |
| VerfasserIn |
C. Liu, K. Wang, X. Zheng |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 9, no. 2 ; Nr. 9, no. 2 (2012-02-22), S.839-850 |
| Datensatznummer |
250006771
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| Publikation (Nr.) |
 copernicus.org/bg-9-839-2012.pdf |
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| Zusammenfassung |
| Model and field studies generally posit that when the application rates of
nitrogen fertilizer exceed crop needs, nitrous oxide (N2O) emissions
will increase nonlinearly, though linear responses are also extensively
reported by field studies. We conducted year-round measurements of crop
yield, N2O and methane (CH4) fluxes for treatments of six
fertilizer nitrogen levels (0, 135, 270, 430, 650 and 850 kg N ha−1 yr−1 in the form of urea) in a typical irrigated wheat-maize rotation
field in northern China. Linear models characterized the responses of
cumulative N2O emissions to fertilizer rates well; therefore, the
calculated N2O emission factors of 0.17 ± 0.02%, 0.73 ± 0.05% and 0.49 ± 0.02% for the wheat season, maize
season and annual scale, respectively, were appropriate for the different
fertilizer rates. The cumulative CH4 uptake by the soil tended to be
enhanced at higher fertilizer rates (≥350 kg N ha−1) in the maize
season whereas no effect was observed for the wheat season. When the annual
fertilizer rates increased from 270 to 430, from 270 to 650, and from 270 to
850 kg N ha−1 yr−1, the crop yields increased only 3 ∼ 15%
(0.5 ∼ 2.1 t ha−1 yr−1), but cumulative N2O emissions
increased 35 ∼ 115% (0.9 ∼ 3.0 kg N ha−1 yr−1). We
recommend 270 kg N ha−1 yr−1 as the locally optimum fertilizer
rate. Considering the nitrogen inputs by fertilization (270 kg N ha−1 yr−1), irrigation (4.3 ± 0.2 kg N ha−1 yr−1) and
deposition (wet deposition: 30.5 ± 1.5 kg N ha−1 yr−1), the
slightly positive soil nitrogen balance could maintain the current crop
yield (∼13.8 t ha−1 yr−1) and reduce the present high
N2O emissions (>3.51 kg N ha−1 yr−1) of the local farmers'
practice (fertilizer rate > 430 kg N ha−1 yr−1). |
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