1. Frozen Cropland Soil in Northeast China as Source of N2O and CO2 Emissions.
- Author
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Miao, Shujie, Qiao, Yunfa, Han, Xiaozeng, Brancher Franco, Roberta, and Burger, Martin
- Subjects
FROZEN ground ,ATMOSPHERIC nitrous oxide ,EMISSIONS (Air pollution) ,ATMOSPHERIC carbon dioxide ,AGRICULTURAL ecology ,FARMS - Abstract
Agricultural soils are important sources of atmospheric N
2 O and CO2 . However, in boreal agro-ecosystems the contribution of the winter season to annual emissions of these gases has rarely been determined. In this study, soil N2 O and CO2 fluxes were measured for 6 years in a corn-soybean-wheat rotation in northeast China to quantify the contribution of wintertime N2 O and CO2 fluxes to annual emissions. The treatments were chemical fertilizer (NPK), chemical fertilizer plus composted pig manure (NPKOM), and control (Cont.). Mean soil N2 O fluxes among all three treatments in the winter (November–March), when soil temperatures are below −7°C for extended periods, were 0.89–3.01 µg N m−2 h−1 , and in between the growing season and winter (October and April), when freeze-thaw events occur, 1.73–5.48 µg N m−2 h−1 . The cumulative N2 O emissions were on average 0.27–1.39, 0.03–0.08 and 0.03–0.11 kg N2 O– N ha−1 during the growing season, October and April, and winter, respectively. The average contributions of winter N2 O efflux to annual emissions were 6.3–12.1%. In all three seasons, the highest N2 O emissions occurred in NPKOM, while NPK and Cont. emissions were similar. Cumulative CO2 emissions were 2.73–4.94, 0.13–0.20 and 0.07–0.11 Mg CO2 -C ha−1 during growing season, October and April, and winter, respectively. The contribution of winter CO2 to total annual emissions was 2.0–2.4%. Our results indicate that in boreal agricultural systems in northeast China, CO2 and N2 O emissions continue throughout the winter. [ABSTRACT FROM AUTHOR]- Published
- 2014
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