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| Effects of different ratooning cultivation modes on greenhouse gas emissions and grain yields in paddy fields |
| Received:November 07, 2018 |
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| KeyWord:CH4;N2O;yield;global warming potential;ratooning rice |
| Author Name | Affiliation | E-mail | | DENG Qiao-jiang | MARA Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River/College of Plant Science & Technology, Huazhong Agricultural University, Wuhan 430070, China | | | CAO Cou-gui | MARA Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River/College of Plant Science & Technology, Huazhong Agricultural University, Wuhan 430070, China
Hubei Collaborative Innovation Center for Grain Industry, Yangtze University, Jingzhou 434023, China | | | LI Cheng-fang | MARA Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River/College of Plant Science & Technology, Huazhong Agricultural University, Wuhan 430070, China
Hubei Collaborative Innovation Center for Grain Industry, Yangtze University, Jingzhou 434023, China | lichengfang@126.com |
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| Abstract: |
| Rice ratooning can be an effective way to enhance the multiple-cropping index of paddy fields, grain yield per unit, and economic benefits. Thus, it has become an important rice cropping pattern in China. However, the effects of ratooning rice on greenhouse gas emissions remain unknown. Therefore, this study investigated the effect of different cultivation modes (traditional and optimized cultivation) on greenhouse gas emissions and grain yields from ratooning rice fields of Guanghua Farm, Qianjiang City, in 2017. The soil N2O and CH4 emissions were determined by a static closed-steel method, and the soil N2O and CH4 fluxes were measured at 7~10 d intervals. The results of this study indicated that there were peaks in N2O fluxes immediately after each N application and after field drainage. Moreover, other peaks in N2O fluxes were found at the heading stages of first rice crops and rice ratooning. The N2O fluxes under the traditional cultivation model ranged from -15.70 μg·m-2·h-1 to 536.24 μg·m-2·h-1 in the first rice season, and from 18.04 μg·m-2·h-1 to 168.38 μg·m-2·h-1 in the ratooning rice season. For the optimized cultivation mode, the fluxes varied from 9.53 μg·m-2·h-1 to 1 031.99 μg·m-2·h-1 in the first rice season, and from 16.54 μg·m-2·h-1 to 338.90 μg·m-2·h-1 in the ratooning rice season. Compared with the traditional cultivation model, the optimized cultivation mode significantly increased contents of soil NH4+-N, NO3--N, and dissolved organic C by 78.7%, 31.8%, and 25.3%, respectively. Cultivation patterns had significant effects on cumulative N2O and CH4 emissions. Compared with traditional cultivation mode, the optimized cultivation mode significantly enhanced cumulative N2O emissions by 82.0%, 45.3%, and 64.0%, but decreased cumulative CH4 emissions by 55.0%, 260.0%, and 34.9%, and reduced global warming potential by 52.7%, 218.6%, and 31.9% in the first, ratooning, and whole rice seasons, respectively. The contribution of CH4 to the global warming potential was 80.7%~98.3%, which was obviously higher than that of N2O (1.7%~19.3%). Moreover, cultivation patterns also significantly affected rice grain yields. Optimized cultivation mode resulted in 23.8%, 30.0%, and 25.4% higher grain yields in the first, ratooning, and whole rice seasons relative to traditional cultivation mode. Together, our results suggest that the optimized cultivation mode is a sustainable ratooning cultivation mode with great global warming mitigation potential and increased grain yields from first and ratooning rice in paddy fields. Thus, it is worth to popularize this cultivation mode in rice planting areas of Hubei Province. |
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