CH4 emission and the concentration of dissolved CH4 in soil solution and floodwater in a rice field and their stable carbon isotopic signatures as affected by straw application were investigated in 2009 in a field exp...CH4 emission and the concentration of dissolved CH4 in soil solution and floodwater in a rice field and their stable carbon isotopic signatures as affected by straw application were investigated in 2009 in a field experiment at Jurong, Jiangsu Province, China. Straw application increased CH4 emission and CH4 concentration in the soil solution and floodwater. A positive seasonal correlation was also observed in the variation between CH4 flux and CH4 concentration in soil solution. The seasonal total CH4 emission （51.6 g CH4 m^-2） in Treatment WS （straw applied） was about 168% higher than that in Treatment CK （without straw）. The emitted CH4 and CH4 in soil solution were initially relatively enriched, then depleted and finally enriched again in 13C in both treatments, while CH4 in floodwater became isotopically heavier. The carbon isotopic signature of emitted CH4 and CH4 in floodwater averaged around -62%o and -45%0 for both treatments, respectively, and was not significantly influenced by the application of straw. However, straw application caused the CH4 in soil solution to be significantly depleted in lac during the middle of the rice season, and the mean δ13C value was lower in WS （-57.5‰） than in CK （-49.9‰）. Calculation from the isotopic data showed that straw application increased the fraction of CH4 oxidized, causing no significant difference in the δ13C value of the emitted CH4 between the two treatments.展开更多
A four-year(2008–2011) field study was implemented in a major rice-growing region of China to better understand the effect of urea and controlled release fertilier(CRF, thermoplastic resin-coated urea in this study) ...A four-year(2008–2011) field study was implemented in a major rice-growing region of China to better understand the effect of urea and controlled release fertilier(CRF, thermoplastic resin-coated urea in this study) on CH4 emission from paddy fields. Over the four years, the average CH4 emission during the rice growing seasons was 76.9, 65.8 and 64.9 kg CH4ha-1in treatments CK(zero N), U(urea) and C(CRF), respectively. Urea and CRF significantly reduced CH4 emission by 14.4% and 15.6%, and increased average rice grain yield by 25.8% and 19.7%(P < 0.05), respectively, compared with treatment CK. Flooding duration would affect CRF's effect on CH4 emission from paddy fields. Under normal aeration conditions, CH4 emission tended to be 3.9%–15.2% lower in treatment C than in treatment U from 2009 to 2011, while it tended to be 4.2% higher under delayed aeration conditions in 2008. The findings suggest that mid-season aeration(MSA) starting on D30(30 days after rice transplanting), just like the local practice, would optimize the CRF's effect on CH4 emission from rice fields in China. Over the four years, average rice yield did not differ between treatments U and C, and tended to be 5% lower in treatment C than in treatment U.展开更多
基金Supported by the National Natural Science Foundation of China (Nos. 40921061 and 41071169)the Strategic Priority Research Program of the Chinese Academy of Sciences (No. XDA05020200)
文摘CH4 emission and the concentration of dissolved CH4 in soil solution and floodwater in a rice field and their stable carbon isotopic signatures as affected by straw application were investigated in 2009 in a field experiment at Jurong, Jiangsu Province, China. Straw application increased CH4 emission and CH4 concentration in the soil solution and floodwater. A positive seasonal correlation was also observed in the variation between CH4 flux and CH4 concentration in soil solution. The seasonal total CH4 emission （51.6 g CH4 m^-2） in Treatment WS （straw applied） was about 168% higher than that in Treatment CK （without straw）. The emitted CH4 and CH4 in soil solution were initially relatively enriched, then depleted and finally enriched again in 13C in both treatments, while CH4 in floodwater became isotopically heavier. The carbon isotopic signature of emitted CH4 and CH4 in floodwater averaged around -62%o and -45%0 for both treatments, respectively, and was not significantly influenced by the application of straw. However, straw application caused the CH4 in soil solution to be significantly depleted in lac during the middle of the rice season, and the mean δ13C value was lower in WS （-57.5‰） than in CK （-49.9‰）. Calculation from the isotopic data showed that straw application increased the fraction of CH4 oxidized, causing no significant difference in the δ13C value of the emitted CH4 between the two treatments.
基金Supported by the Key Program for International S&T Cooperation Projects of China(No.2012DFG90290)the Non-Profit Research Foundation for Agriculture,China(No.201103039)+1 种基金the National Natural Science Foundation of China(Nos.41271259 and 412012433)the Research Fund of State Key Laboratory of Soil and Sustainable Agriculture,Institute of Soil Science,Chinese Academy of Sciences(No.Y412201414)
文摘A four-year(2008–2011) field study was implemented in a major rice-growing region of China to better understand the effect of urea and controlled release fertilier(CRF, thermoplastic resin-coated urea in this study) on CH4 emission from paddy fields. Over the four years, the average CH4 emission during the rice growing seasons was 76.9, 65.8 and 64.9 kg CH4ha-1in treatments CK(zero N), U(urea) and C(CRF), respectively. Urea and CRF significantly reduced CH4 emission by 14.4% and 15.6%, and increased average rice grain yield by 25.8% and 19.7%(P < 0.05), respectively, compared with treatment CK. Flooding duration would affect CRF's effect on CH4 emission from paddy fields. Under normal aeration conditions, CH4 emission tended to be 3.9%–15.2% lower in treatment C than in treatment U from 2009 to 2011, while it tended to be 4.2% higher under delayed aeration conditions in 2008. The findings suggest that mid-season aeration(MSA) starting on D30(30 days after rice transplanting), just like the local practice, would optimize the CRF's effect on CH4 emission from rice fields in China. Over the four years, average rice yield did not differ between treatments U and C, and tended to be 5% lower in treatment C than in treatment U.
