| Global warming is a global environmental problem nowadays.Carbon dioxide（CO2）,methane（CH4）and nitrous oxide（N2O）are the three most key greenhouse gases.Paddy ecosystem is an important source of greenhouse gas（CH4 and N2O）emissions in agriculture system.While ensuring food security,reducing greenhouse gas emissions from paddy field is an essential task to cope with global climate change.The greenhouse gas emission of rice field is affected by soil property,climate condition,cultivation management and varietal characteristic.Crop simulation model provides a new method for quantitative analysis of the impact of different factors on greenhouse gas emission.In this study we combined the soil data,weather data,cultivars and management information in the 1980 s,2000 s and the future with DNDC model and GIS technology to simulate and quantify the effects of soil,climate change,cultivars update and management improvement on rice productivity and greenhouse gas emissions across Tai Lake region.The changes of rice yield and greenhouse gas（CH4,N2O）in Tai Lake region relative to 1980-2009 under 1.5℃ and 2.0℃ HAPPI scenarios,and the possible effects of increasing temperature and CO2 fertilization on that were evaluated.Finally,the impaction of different fertilization rates,irrigation methods and straw returning rates on rice yield and greenhouse gas emissions in Tai Lake region were simulated and quantified by DNDC.The results would provide support for optimizing rice production and management,reducing greenhouse gas emissions in Tai Lake region,providing theoretical support for promoting sustainable development of agriculture,and would be of great significance for alleviating greenhouse effect,improving climate change and ensuring food security.The spatial and temporal characteristics of rice yield and greenhouse gas emissions in the 1980s,2000s and the scenarios of 1.5℃ and 2.0℃ temperature increase were analyzed by means of DNDC model and GIS.Then,the composition contribution rate of soil renewal,climate change,optimization of management measures and variety improvement to rice yield and greenhouse gas emissions in the Tai Lake region was analyzed.The results in this study showed that the yield and greenhouse gas emissions were both higher in the 2000s than the 1980s,and the yield-scaled GWP was lower than that in the 1980s across Tai Lake region.Factors such as soil,climate,management,varieties of rice had different influence on the rice yield and greenhouse gas emissions.The optimization of management measures significantly increased the rice yield,reduced the yield-scaled GWP in the 2000s,climate change and soil increased the yield-scaled GWP.Rice varieties improved both the yield and CH4 emissions,but they had smaller effects on GWP per unit of production.The effect of the two-factor combination on rice yield and greenhouse gas emissions was basically the same as that of the single-factor one.The optimization of management measures,along with other factors,reduced the yield-scaled GWP.Under the scenario of 1.5℃ and 2.0℃temperature increase,gas emissions and the yield-scaled GWP increased.The increase of CO2 concentration could mitigate the negative impact of future climate warming on rice yield,but at the same time it increased the yield-scaled GWP.The effects of different management measures on rice yield and greenhouse gas emissions in Tai Lake region were simulated and analyzed by setting up simulation scenarios of different fertilizer rates,irrigation methods and straw returning rates.The results showed that:1)the increase of nitrogen application significantly increased the rice yield in the Tai Lake region,and to some extent increased CH4 and N2O emissions in the rice field.However,with the increase of nitrogen application,the the yield-scaled GWP showed a trend of increasing first and then decreasing.2)the drainage and moist intermittent irrigation had no significant effect on the yield,but significantly reduced the CH4 emission,increased the N20 emission,to some extent,and reduced the per unit yield in the paddy field in Tai Lake region.3)straw returning increased rice yield in the Tai Lake region,but also aggravated greenhouse gas（CH4,N2O）emissions and increases the yield-scaled GWP in the rice field.In general,the maximum yield can be obtained when the irrigation method is F-D or F-D-M,and the application rate of fertilizer is 300kg N/ha or above,and the straw is returned to the field by more than 50%.When the irrigation method is F-M,the straw is not returned to the field,and the fertilizer rate is 300-400kg N/ha,the yield-scaled GWP is the lowest.When the irrigation method is F-D-M,the straw is not returned,and the fertilizer rate is 300kg N/ha,the goal of high yield and emission reduction can be achieved simultaneously. |
PDF Full Text Request