Affiliations: College of Resource and Environment, Southwest
Agricultural University, Chongqing 400716, China | Chongqing Key Laboratory of Digital Agriculture,
Chongqing 400716, China | Institute of Soil Science, Chinese Academy of
Sciences, Nanjing 210008, China
Abstract: The terrestrial ecosystem may be either a source or a sink of
CH_4 in rice paddies, depending, to a great extent, on the
change of ecosystem types and land use patterns. CH_4 emission fluxes
from paddy fields under 4 cultivation patterns (conventional plain culture of
rice (T1), no-tillage and ridge culture of rice (T2), no-tillage and ridge
culture of rice and wheat (T3), and rice-wheat rotation (T4)) were measured
with the closed chamber technique in 1996 and 1998 in Chongqing, China. The
results showed that differences existed in CH<FORMULA>_4 emission
from paddy fields under these land management practices. In 1996 and 1998,
CH_4 emission was 71.48% and 78.82% (T2), 65.93% and 57.18%
(T3), and 61.53% and 34.22% (T4) of that in T1 during the rice growing season.
During the non-rice growing season, CH_4 emission from rice
fields was 76.23% in T2 and 38.69% in T1. The accumulated annual
CH_4 emission in T2, T3 and T4 in 1996 decreased by 33.53%,
63.30% and 65.73%, respectively, as compared with that in T1. In 1998, the
accumulated annual CH_4 emission in T1, T2, T3 and T4 was
116.96 g/m^2, 68.44 g/m^2, 19.70
g/m^2 and 11.80 g/m^2, respectively.
Changes in soil physical and chemical properties, in thermal and moisture
conditions in the soil and in rice plant growth induced by different land use
patterns were the dominant causes for the difference in CH_4
emission observed. The relative contribution of various influencing factors to
CH_4 emission from paddy fields differed significantly under
different land use patterns. However, the general trend was that chlorophyll
content in rice leaves, air temperature and temperature at the 5 cm soil layer
play a major role in CH_4 emission from paddy fields and the
effects of illumination, relative humidity and water layer depth in the paddy
field and CH_4 concentration in the crop canopy were
relatively non-significant. Such conservative land use patterns as no-tillage
and ridge culture of rice with or without rotation with wheat are thought to be
beneficial to reducing CH_4 emission from paddy fields and
are, therefore, recommended as a significant solution to the problems of global
(climatic) change.
Keywords: land use pattern, microcosmic cultivation scale, fluxes of CH[TeX:] _4 emission, paddy field
