Greenhouse gas emissions,nitrogen and phosphorous losses through ammonia volatilization,leaching and surface drainage from rice paddy under efficient irrigation and drainage were analyzed based on field experimental d...Greenhouse gas emissions,nitrogen and phosphorous losses through ammonia volatilization,leaching and surface drainage from rice paddy under efficient irrigation and drainage were analyzed based on field experimental data in order to reveal the eco-environmental impacts of efficient irrigation and drainage on rice paddy.The results showed that total methane emission from rice paddy under the controlled irrigation was reduced by more than 80% and total nitrous oxide emission increased by 15.9% compared with flooding irrigation.Seasonal comprehensive global warming potentials(GWP) of methane and nitrous oxide were 62.23 gCO2 m-2 for rice paddy under the controlled irrigation,reduced by 68.0% compared with flooding irrigation.Due to large reduction in seepage and surface drainages,nitrogen and phosphorous losses through leaching were reduced by 40.1% and 54.8%,nitrogen and phosphorous losses through surface drainage were reduced by 53.9% and 51.6% from rice paddy under efficient irrigation and drainage compared with traditional irrigation and drainage.Nitrogen loss through ammonia volatilization was reduced by 14.0%.Efficient irrigation and drainage management is helpful to mitigate greenhouse gases emission,nitrogen and phosphorus losses and their pollution on groundwater and surface water.展开更多
Soil organic carbon （SOC） and iron （Fe）-oxides are important contributors of aggregate stability in highly weathered soils, and they are influenced by groundwater management and straw application. A 30-year plot e...Soil organic carbon （SOC） and iron （Fe）-oxides are important contributors of aggregate stability in highly weathered soils, and they are influenced by groundwater management and straw application. A 30-year plot experiment with early rice （Oryza sativa L.）-late rice-winter fallow rotations was conducted using a upland clay soil in cement pools under shallow groundwater table at a depth of 20 am （SGT） aud deep groundwater table at a depth of 80 cm （DGT） to simulate the groundwater tables of two types of important paddy soils, gleyed paddy soils and hydromorphic paddy soils, respectively, in subtropical China. Soil redox potential （Eh） was measured in situ, and 0-20 cm soil samples were collected for the analyses of soil Fe-oxides, SOC, and aggregates under SGT or DGT with different straw application treatments, in order to evaluate the interaction of groundwater management and straw application on paddy soil aggregation and the relative importance of SOC or Fe-oxides on soil aggregation. The results showed that soil Eh was restricted by irrigation, and its variation was more significant under DGT than under SGT. The decreased soil Eh or reduced drying and wetting cycles under SGT resulted in more SOC accumulation with the straw application, had no effect on soil free Fe-oxides （Fed）, significantly increased the amorphous Fe-oxide （Feo） and complex Fe-oxide contents, but decreased the crystalline Fe-oxide content （Fed-Feo）. The soils under DGT had more macroaggregates than those under SGT, but the difference decreased with the straw application. It could be concluded that soil Fe-oxides were the principal contributing factor to the aggregation of paddy soils in subtropical China and SOC was also an important contributing factor.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos 50839002 and 50809022)the National Key Tech-nologies R & D Program of China during the 11th Fiveyear Plan Period (Grant No 2006BAD11B09)
文摘Greenhouse gas emissions,nitrogen and phosphorous losses through ammonia volatilization,leaching and surface drainage from rice paddy under efficient irrigation and drainage were analyzed based on field experimental data in order to reveal the eco-environmental impacts of efficient irrigation and drainage on rice paddy.The results showed that total methane emission from rice paddy under the controlled irrigation was reduced by more than 80% and total nitrous oxide emission increased by 15.9% compared with flooding irrigation.Seasonal comprehensive global warming potentials(GWP) of methane and nitrous oxide were 62.23 gCO2 m-2 for rice paddy under the controlled irrigation,reduced by 68.0% compared with flooding irrigation.Due to large reduction in seepage and surface drainages,nitrogen and phosphorous losses through leaching were reduced by 40.1% and 54.8%,nitrogen and phosphorous losses through surface drainage were reduced by 53.9% and 51.6% from rice paddy under efficient irrigation and drainage compared with traditional irrigation and drainage.Nitrogen loss through ammonia volatilization was reduced by 14.0%.Efficient irrigation and drainage management is helpful to mitigate greenhouse gases emission,nitrogen and phosphorus losses and their pollution on groundwater and surface water.
基金financially supported by the National Natural Science Foundation of China (No. 41371250)
文摘Soil organic carbon （SOC） and iron （Fe）-oxides are important contributors of aggregate stability in highly weathered soils, and they are influenced by groundwater management and straw application. A 30-year plot experiment with early rice （Oryza sativa L.）-late rice-winter fallow rotations was conducted using a upland clay soil in cement pools under shallow groundwater table at a depth of 20 am （SGT） aud deep groundwater table at a depth of 80 cm （DGT） to simulate the groundwater tables of two types of important paddy soils, gleyed paddy soils and hydromorphic paddy soils, respectively, in subtropical China. Soil redox potential （Eh） was measured in situ, and 0-20 cm soil samples were collected for the analyses of soil Fe-oxides, SOC, and aggregates under SGT or DGT with different straw application treatments, in order to evaluate the interaction of groundwater management and straw application on paddy soil aggregation and the relative importance of SOC or Fe-oxides on soil aggregation. The results showed that soil Eh was restricted by irrigation, and its variation was more significant under DGT than under SGT. The decreased soil Eh or reduced drying and wetting cycles under SGT resulted in more SOC accumulation with the straw application, had no effect on soil free Fe-oxides （Fed）, significantly increased the amorphous Fe-oxide （Feo） and complex Fe-oxide contents, but decreased the crystalline Fe-oxide content （Fed-Feo）. The soils under DGT had more macroaggregates than those under SGT, but the difference decreased with the straw application. It could be concluded that soil Fe-oxides were the principal contributing factor to the aggregation of paddy soils in subtropical China and SOC was also an important contributing factor.
