Effect of rice plants on CH4 production, transport, oxidation and emission in rice paddy soil (original) (raw)
Related papers
Soil Science and Plant Nutrition, 2006
Methane production potential (MPP) of rice soil, defined here as the mean value of methane production rate (MP-R) of rice soil over a given period in which the substrate for methanogenesis is presumably depleted, significantly affects CH 4 emission to the atmosphere. To expand our understanding of how MPP was affected in soils grown with different rice cultivars (Yanxuan, 72031 and 9516) and its consequence on CH 4 emission, the changing pattern of MP-R was elucidated in the present study. On an entire rice growing scale, the MPP of planted soil was significantly higher than that of unplanted soil, and the MPP of 72031 rice soil was 9.42 µg CH 4 kg (d.w.s) −1 h −1 , significantly lower than Yanxuan (18.2 µg CH 4 kg (d.w.s) −1 h −1) and 9516 rice soils (17.7 µg CH 4 kg (d.w.s) −1 h −1). Yanxuan and 9516 soils had a similar MP-R changing pattern, which was distinct from 72031 soil. On a temporal scale of the representative rice growing stages (i.e. early tillering, late tillering, panicle initiation, ripening and harvesting stages), the MPP of rice soils varied widely among rice cultivars, and MPP coincided well with CH 4 emission regardless of rice cultivars. No clear pattern was observed in soil redox potential (soil E h), or in above-ground biomass of rice cultivars to MPP and CH 4 emission.
Methane emission from rice fields in China: Measurements and influencing factors
Journal of Geophysical Research, 2000
Methane emissions from rice fields in China were measured at eight sites in five provinces under conditions representative of local practices for rice cultivation. Methane emission rates during the rice growth period varied greatly from site to site and with treatments at the same site, ranging from 0.3 to 205 g CH4/m 2. Flooded or waterlogged rice fields in the nonrice growth season continuously emitted CH4 substantially. The average CH4 emission rate from a rice field in Chongqing was as high as 36.2 g CH4/m 2 in the nonrice growing season. Furthermore, flooding in the nonrice growth season also significantly stimulated CH4 emission during the rice growth period in the next year. Increases in the rate of CH4 flux after rice transplanting were less when the number of consecutive upland crops grown before rice transplanting was greater. CH4 emissions from rice fields located on downslope was larger than from those on midslope and upslope in hilly areas due to poor drainage of the former. Application of rice straw in fall when winter wheat was sown did not increase CH4 emission significantly during the following rice growth period. CH4 emission was depressed by the application of ammonium sulfate but was, in general, not significantly affected by urea application.
Methane production, oxidation, and emission from Indian rice soils
Methane Emissions from Major Rice Ecosystems in Asia, 2000
Experiments were conducted to investigate methane (CH 4 ) production, oxidation, and emission from flooded rice soils. Incorporation of green manure (Sesbania rostrata) into rice fields led to a several-fold increase in CH 4 emission. A stimulatory effect of organic sources on CH 4 production in soil samples was noticed even under nonflooded conditions. Addition of rice straw at 1% (w/w) to nonflooded soil samples held at -1.5 MPa effected a 230-fold increase in CH 4 production over that in corresponding unamended soil samples at 35 d, as compared with a threefold increase in rice straw-amended soil over that in unamended soil under flooded conditions. In a study involving two experimental field sites differing in water regimes but planted to the same rice cultivar (cv Gayatri) and fertilized with prilled urea at 60 kg N ha -1 , the field plots with deep submergence of around 30 cm (site I) emitted distinctly more CH 4 than did the plots with continuous water depth of 3-6 cm (site II). Likewise, in another incubation study, CH 4 production in flooded soil samples increased with a progressive increase in standing water column from 5 mm to 20 mm. Application of carbamate insecticide, carbofuran, at 2 kg ai ha -1 to rice fields retarded CH 4 emission through enhanced CH 4 oxidation. Hexachlorocyclohexane was found to inhibit CH 4 emission. The results suggest the need for extensive research efforts to develop technologies with dual objectives of environmental protection and crop productivity.
Hydrological Processes, 1998
Total amounts of CH 4 emission from a Sumatra rice ®eld were in the ranges 29 . 5±48 . 2 and 43 . 0±64 . 6 g CH 4 m À2 season À1 for the plots with chemical fertilizer (CF-plot) and those with rice straw application (RS-plot), respectively. Nearly the same amounts of CH 4 were emitted in the ®rst and second half of the growth period, irrespective of rice straw application. The increase in the amounts of CH 4 emission by rice straw application were from 1 . 3 to 1 . 6 times. There was no signi®cant dierence in the mean CH 4 emission rates between rainy and dry seasons. Rain-fed conditions decreased the CH 4 emission by 27±37% compared with continuously¯ooded conditions. Total amounts of CH 4 emission from a rice ®eld growing eight popular modern rice varieties in Indonesia were in the ranges 32 . 6±41 . 7 and 51 . 3±64 . 6 g CH 4 m À2 season À1 for CFand RS-plots, respectively. Total amounts of CH 4 emission from four Sumatra rice ®elds with dierent soil types (a Typic Paleudult, a Typic Sulfaquent, a Typic Tropohumult and a Typic Tropopsament) were in the range 22 . 1 (a Typic Sulfaquent) to 53 . 4 (a Typic Tropohumult) g CH 4 m À2 season À1 for CF-plots and from 26 . 7 (a Typic Sulfaquent) to 72 . 2 (a Typic Tropohumult) g CH 4 m À2 season À1 for RS-plots. CH 4 emission rates from Bali rice ®elds with soils of volcanic ash origin were very low; 3 . 5±7 . 7 and 5 . 3±14 . 3 g CH 4 m À2 season À1 for CF-and RS-plots, respectively.
Contribution of Rice Plants and Cover Crop Biomass Amended Soil on Methane Emission
American Journal of Climate Change, 2018
Rice plant and soil are playing vital role for produce of methane (CH 4) emission from flooded rice soil. Contribution of rice plants and cover crop biomass amended soil on methane emission has not been yet studied under different cover crop biomass incorporated in paddy fields. Closed-chamber method was used to estimate CH 4 emission rates during rice cultivation under soil plus rice plants and soil alone condition. Soil plus rice plants chambers 62 × 62 × 112 cm 3 and soil alone chambers 20 × 20 cm 2 were placed at the same time during rice cultivation (0 days after rice transplanting). Therefore, to evaluate the contribution of soil plus rice plants and soil alone on methane (CH 4) emission under different rates of cover crop biomass incorporated soil during rice cultivation. Methane emission from soil plus rice plants increased up to 53 days after transplanting (DAT) and then it's decreased and continued till harvesting. It was found that ca. 47%-52% CH 4 was mediated by rice plants and ca. 48%-53% through rice soil alone under 12 Mg•ha −1 cover crop biomass incorporated treated plots. Whereas, only ca. 9%-10% CH 4 emission was mediated by rice plants and ca. 90%-91% by rice soil alone when 0 and 3 Mg•ha −1 cover crop biomass was incorporated. Therefore, it could be concluded that rice soil alone was more influenced for CH 4 emission than rice plants in paddy fields.
1997
Measurements focused on seasonal contribution of rice productivity to methane emission were made in three experiments conducted in Texas flooded paddy soils during 1994 and 1995 growing seasons. A total of five rice cultivars representing two distinct groups in methane emission were involved. Over a 10-week period after permanent flooding, total seasonal methane emission was positively correlated with rice above-ground biomass (r 2 ϭ 0.845, n ϭ 11). A very strong dependence of daily methane emission on above-ground vegetative biomass (r 2 ϭ 0.887, n ϭ 93) and on root biomass (r 2 ϭ 0.816, n ϭ 33) was also observed. Calculation from three developmental periods (vegetative, reproductive and ripening) of rice plant indicated that more than 75% of total seasonal methane was emitted during the last 5-week period in concert with reproductive and ripening stages, while rice biomass production during the same period amounted to µ 50% of the seasonal total. According to the correlation of cumulative methane emission with above-ground biomass increment between every two-week interval (r 2 ϭ 0.490, n ϭ 93, P ϭ 0.000), the carbon released as methane is approximately equivalent to 3% and 4.5% of photosynthetically fixed carbon in the biomass for low and high emission cultivars, respectively. A further investigation showed that these fractions are related to plant growth and development. The carbon ratio of methane emitted to net photosynthetic production during vegetative, reproductive, and ripening periods averaged 0.9%, 3.6% and 7.9%, respectively, for low emission cultivars, and 2.0%, 5.0% and 8.3%, respectively, for high emission cultivars. Moreover, the ratio was strongly dependent on plant biomass, resulting in r 2 values from 0.775 to 0.907.
Factors affecting methane emission from rice fields
Atmospheric Environment, 1996
Emission of CH4 from ricefields is the result of anoxic bacterial methane production. Global estimates of annual CH4 emission from ricefields is 100 Tg. CH4 emission data from limited sites are tentative. It is essential that uncertainty in individual sources is reduced in order to develop feasible and effective mitigation options which do not negate gains in rice production and productivity. Field studies at the International Rice Research Institute show that soil and added organic matter are the sources for initial methane production. Addition of rice straw enhances methane production. Roots and root exudates of wetland rice phmts appear to be the major carbon sources at ripening stage. The production and transport of CH4 to the atmosphere depend on properties of the rice plant. Under the same spacing and fertilization, the traditional variety Dular emitted more CH4 per day than did the new plant type IR65597. Upon flooding for land preparation anaerobic conditions result in significant amount of methane being formed. Drying the field at midtillering significantly reduced total CH4 emissions. Large amounts of entrapped CH4 escape to the atmosphere when floodwater recedes upon drying at harvest. Cultural practices may account for 20% of the overall seasonal CH4 emissions.
Global Change Biology, 2008
A pot experiment was conducted to investigate CH 4 emissions from a sandy paddy soil as influenced by rice cultivars and atmospheric CO 2 elevation. The experiment with two CO 2 levels, 370 lL L À1 (ambient) and 570 lL L À1 (elevated), was performed in a climatron, located at the National Institute for Agro-Environmental Sciences, Tsukuba, Japan. Four rice cultivars were tested in this experiment, including IR65598, IR72, Dular and Koshihikari. Tiller number, root length and grain yield were clearly larger under elevated CO 2 than under ambient CO 2. IR72 and Dular showed significantly higher tiller number, root length and grain yield than Koshihikari and IR65598. Average daily CH 4 fluxes under elevated CO 2 were significantly larger by 10.9-23.8% than those under ambient CO 2 , and varied with the cultivars in the sequence Dular^IR724IR65598^Koshihikari. Dissolved organic C (DOC) content in the soil was obviously higher under elevated CO 2 than under ambient CO 2 and differed among the cultivars, in the sequence IR724Dular4Koshihikari4IR65598. The differences in average daily CH 4 fluxes between CO 2 levels and among the cultivars were related to different root exudation as DOC content, root length and tiller number. This study indicated that Koshihikari should be a potential cultivar for mitigating CH 4 emission and simultaneously keeping stable grain yield, because this cultivar emitted lowest CH 4 emission and produced medium grain yield.