耕作方式对华北农田土壤有机碳储量及温室气体排放的影响

耕作方式能够改变土壤有机碳在土层中的分布,进而对土壤有机碳及土壤碳储量产生影响。该研究在模型调整的基础上选取了土壤有机碳(SOC)、土壤碳密度(SCD)、土壤呼吸(SR)以及生物量碳(BC)4个指标对DNDC(denitrification-decomposition)模型在华北麦-玉两熟农田的适用性进行验证,并用该模型模拟当地土壤碳储量(SCS)动态变化以及温室气体排放特征。结果表明,模型模拟值与实测值吻合良好,此模型可以适用于华北麦-玉两熟农田土壤有机碳的模拟研究;2001-2010年SOC和SCS逐年递增;对未来100a模拟发现,前15a旋耕(RT)和翻耕(CT)处理SOC增长迅速,而免耕(NT)SOC的剧烈增长趋势要持续近40a;对比各处理100a碳储量变化可知,前20aCT处理SCS最大,20a后NT处理SCS最大;各处理土壤全球变暖潜势(GWP)大小为CT>RT>NT。通过验证该文证明了DNDC模型可以较好地研究华北麦-玉两熟农田土壤碳循环;长久来看NT有利于农田SCS的积累以及GWP的降低。该研究能够为华北麦-玉两熟农作区固碳减排提供依据。

Effects of tillage practices on soil carbon storage and greenhouse gas emission of farmland in North China

Distribution of soil organic carbon in different soil layer can be transformed by tillage practices, and then soil carbon storage was changed. The four indices of soil organic carbon (SOC), soil carbon density (SCD), soil respiration (SR) and biomass carbon (BC) were selected to verify the adaptability of DNDC model in North China based on model adaptation and then the model was used to simulate local dynamic change of soil carbon storage (SCS) and characteristics of greenhouse gas emission. The result showed that there was a high similarity between simulated values and observed values and the model proposed was suitable to apply to the simulation research of soil organic carbon for winter wheat-summer corn in North China. SOC and SCS simulated by the model increased from 2001-2010, and simulated data in the next 100 years showed that SOC with rotary tillage (RT), conventional tillage (CT) and no-tillage (NT) showed a severe rising tendency in the first 15 years, and rising tendency of NT could sustain for 40 years. By comparing changes of soil carbon storage for 100 years between each treatment, it was found that SCS values with CT were the highest in the first 20 years and SCS values with NT was the highest after first 20 years. The sequence of global warming potential (GWP) for each treatment was CT>RT>NT. The results showed that DNDC model could work well for winter wheat-summer corn in North China, and NT was beneficial to increase SCS and decrease GWP of farmland in the long run. It provides a reference for fixing carbon and reducing discharge of winter wheat-summer corn in North China.