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Changes in fertilizer‐induced direct N 2 O emissions from paddy fields during rice‐growing season in China between 1950s and 1990s
Author(s) -
ZOU JIANWEN,
HUANG YAO,
QIN YANMEI,
LIU SHUWEI,
SHEN QIRONG,
PAN GENXING,
LU YANYU,
LIU QIAOHUI
Publication year - 2009
Publication title -
global change biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.146
H-Index - 255
eISSN - 1365-2486
pISSN - 1354-1013
DOI - 10.1111/j.1365-2486.2008.01775.x
Subject(s) - paddy field , irrigation , environmental science , drainage , fertilizer , nitrogen , growing season , agronomy , nitrous oxide , waterlogging (archaeology) , field experiment , hydrology (agriculture) , wetland , biology , chemistry , ecology , geotechnical engineering , organic chemistry , engineering
Nitrogen fertilizer‐induced direct nitrous oxide (N 2 O) emissions depend on water regimes in paddy fields, such as seasonal continuous flooding (F), flooding–midseason drainage–reflooding (F‐D‐F), and flooding–midseason drainage–reflooding–moist intermittent irrigation but without water logging (F‐D‐F‐M). In order to estimate the changes in direct N 2 O emission from paddy fields during the rice‐growing season in Mainland of China between the 1950s and the 1990s, the country‐specific emission factors of N 2 O‐N under different water regimes combined with rice production data were adopted in the present study. Census statistics on rice production showed that water management and nitrogen input regimes have changed in rice paddies since the 1950s. During the 1950s–1970s, about 20–25% of the rice paddy was continuously waterlogged, and 75–80% under the water regime of F‐D‐F. Since the 1980s, about 12–16%, 77%, and 7–12% of paddy fields were under the water regimes of F, F‐D‐F, and F‐D‐F‐M, respectively. Total nitrogen input during the rice‐growing season has increased from 87.5 kg N ha −1 in the 1950s to 224.6 kg N ha −1 in the 1990s. The emission factors of N 2 O‐N were estimated to be 0.02%, 0.42%, and 0.73% for rice paddies under the F, F‐D‐F, and F‐D‐F‐M water regimes, respectively. Seasonal N 2 O emissions have increased from 9.6 Gg N 2 O‐N each year in the 1950s to 32.3 Gg N 2 O‐N in the 1990s, which is accompanied by the increase in rice yield over the period 1950s–1990s. The uncertainties in N 2 O estimate were estimated to be 59.8% in the 1950s and 37.5% in the 1990s. In the 1990s, N 2 O emissions during the rice‐growing season accounted for 8–11% of the reported annual total of N 2 O emissions from croplands in China, suggesting that paddy rice development could have contributed to mitigating agricultural N 2 O emissions in the past decades. However, seasonal N 2 O emissions would be increased, given that saving‐water irrigation and nitrogen inputs are increasingly adopted in rice paddies in China.