【目的】基于不同复杂度的DNDC和RothC模型,模拟旱地不同秸秆还田量下土壤有机碳(SOC)的动态变化,对比模型结果差异及其成因,为耕地SOC动态模拟的模型选择提供参考。【方法】试验数据(气候、土壤、作物等)来自北京昌平土壤质量国家野外...【目的】基于不同复杂度的DNDC和RothC模型,模拟旱地不同秸秆还田量下土壤有机碳(SOC)的动态变化,对比模型结果差异及其成因,为耕地SOC动态模拟的模型选择提供参考。【方法】试验数据(气候、土壤、作物等)来自北京昌平土壤质量国家野外科学观测研究站长期定位试验,试验始于2008年。包括单施化肥(NPK)、化肥加作物秸秆(NPKS)和化肥加有机肥(NPKM)3个处理。采用DNDC和RothC模型,模拟旱地农田SOC动态变化,应用实测的耕层0—20 cm SOC密度对模型进行校准与验证。基于所验证的模型对比分析不同秸秆还田量(0、2250、4500 kg/hm^(2))情景下的农田SOC动态变化模拟结果。【结果】总体上,两个模型对耕层SOC的模拟均取得了良好的效果,nRMSE均小于20%,nARE绝对值均小于15%,r在0.69至0.91之间,表明这两个模型均适用于该研究区旱地农田SOC动态模拟研究。随着模拟年限的增加,不同秸秆还田量情景下的SOC密度均表现为逐渐增加,但增速逐渐减缓,并且秸秆还田量越多,SOC密度增加越明显。由于两个模型在根系碳输入量计算方式上的不同,其预测的SOC变化幅度有所差异,在预测的第190年,DNDC模型预测结果显示,秸秆不还田、半量还田和全量还田情景下,SOC密度分别比预测的第1年增加了39%、95%和147%。RothC模型的预测结果显示,在相同情景下,SOC密度分别增加了104%、206%和307%。【结论】DNDC与RothC模型在模拟旱地SOC动态方面均表现良好,对不同秸秆还田水平下SOC的变化趋势预测较为一致。RothC模型结构简单、所需输入参数少,适用于SOC快速模拟评估,可在旱地秸秆还田情境下替代DNDC模型用于预测SOC动态。而DNDC模型模拟了复杂的作物生长与土壤生物地球化学循环过程,更适用于综合模拟评估。展开更多
Crop straw incorporation is widely recommended to maintain crop yields and improve soil organic carbon(SOC)stocks as well as soil quality.However,the long-term effects of different straw incorporation practices on the...Crop straw incorporation is widely recommended to maintain crop yields and improve soil organic carbon(SOC)stocks as well as soil quality.However,the long-term effects of different straw incorporation practices on the SOC stock remain uncertain.In this study,a long-term experiment(2007 to 2018)with four treatments(MW_0:maize–wheat rotation with no straw incorporation,MW_(50):maize–wheat rotation with 50%chopped straw incorporation,MW_(b50):maize–wheat rotation with 50%in situ burned harvested straw,and MF_(50):maize–fallow rotation with 50%harvested maize straw incorporation)was set up to evaluate the response of the SOC stock to different straw incorporation methods.The results showed that the SOC stock significantly increased by 32.4,12.2 and 17.4%under the MW_(50),MW_(b50)and MF_(50)treatments,respectively,after continuous straw incorporation over a decade,while the SOC stock under MW0 was significantly reduced by 22.9%after the 11 year long-term experiment.Compared to MW_0,straw incorporation significantly increased organic carbon input,and improved the soil aggregate structure and the ratio of dissolved organic carbon(DOC)to particulate organic carbon(POC),but it did not significantly stimulate soil heterotrophic respiration,resulting in the increased SOC accumulation rate and SOC stocks of bulk soil.The increased ratio of DOC to microbial biomass carbon(MBC)enhanced the relative abundances of Acidobacteria and Proteobacteria but inhibited Bacteroidetes and Chloroflexi,and the bacterial relative abundances were the main reasons for the non-significant increase or even decrease in soil heterotrophic respiration with straw incorporation.The SOC stock would reach an equilibrium based on the results of Rothamsted carbon(RothC)model simulations,with a long-term equilibrium value of 18.85 Mg ha^(–1)under MW_(50).Overall,the results of the long-term field experiment(2007–2018)and RothC model simulation suggested that maize–wheat rotation with 50%chopped straw incorporation delivered the largest benefits for the SOC stock in calcareous soils of subtropical mountain landscapes over the long term.展开更多
文摘【目的】基于不同复杂度的DNDC和RothC模型,模拟旱地不同秸秆还田量下土壤有机碳(SOC)的动态变化,对比模型结果差异及其成因,为耕地SOC动态模拟的模型选择提供参考。【方法】试验数据(气候、土壤、作物等)来自北京昌平土壤质量国家野外科学观测研究站长期定位试验,试验始于2008年。包括单施化肥(NPK)、化肥加作物秸秆(NPKS)和化肥加有机肥(NPKM)3个处理。采用DNDC和RothC模型,模拟旱地农田SOC动态变化,应用实测的耕层0—20 cm SOC密度对模型进行校准与验证。基于所验证的模型对比分析不同秸秆还田量(0、2250、4500 kg/hm^(2))情景下的农田SOC动态变化模拟结果。【结果】总体上,两个模型对耕层SOC的模拟均取得了良好的效果,nRMSE均小于20%,nARE绝对值均小于15%,r在0.69至0.91之间,表明这两个模型均适用于该研究区旱地农田SOC动态模拟研究。随着模拟年限的增加,不同秸秆还田量情景下的SOC密度均表现为逐渐增加,但增速逐渐减缓,并且秸秆还田量越多,SOC密度增加越明显。由于两个模型在根系碳输入量计算方式上的不同,其预测的SOC变化幅度有所差异,在预测的第190年,DNDC模型预测结果显示,秸秆不还田、半量还田和全量还田情景下,SOC密度分别比预测的第1年增加了39%、95%和147%。RothC模型的预测结果显示,在相同情景下,SOC密度分别增加了104%、206%和307%。【结论】DNDC与RothC模型在模拟旱地SOC动态方面均表现良好,对不同秸秆还田水平下SOC的变化趋势预测较为一致。RothC模型结构简单、所需输入参数少,适用于SOC快速模拟评估,可在旱地秸秆还田情境下替代DNDC模型用于预测SOC动态。而DNDC模型模拟了复杂的作物生长与土壤生物地球化学循环过程,更适用于综合模拟评估。
基金financially supported by the National Key Research and Development Program of China(2023YFD1901200)the National Natural Science Foundation of China(U22A20562)+4 种基金the Sichuan Science and Technology Program,China(2022YFS0500)the Project of Special Research Assistant of the Chinese Academy of Sciences(Jing Zheng)the China Postdoctoral Science Foundation(2022M723079)the Sichuan Provincial Postdoctoral Research Foundation,China(TB2022042)the Science and Technology Research Program of Institute of Mountain Hazards and Environment,Chinese Academy of Sciences(IMHEZYTS-08)。
文摘Crop straw incorporation is widely recommended to maintain crop yields and improve soil organic carbon(SOC)stocks as well as soil quality.However,the long-term effects of different straw incorporation practices on the SOC stock remain uncertain.In this study,a long-term experiment(2007 to 2018)with four treatments(MW_0:maize–wheat rotation with no straw incorporation,MW_(50):maize–wheat rotation with 50%chopped straw incorporation,MW_(b50):maize–wheat rotation with 50%in situ burned harvested straw,and MF_(50):maize–fallow rotation with 50%harvested maize straw incorporation)was set up to evaluate the response of the SOC stock to different straw incorporation methods.The results showed that the SOC stock significantly increased by 32.4,12.2 and 17.4%under the MW_(50),MW_(b50)and MF_(50)treatments,respectively,after continuous straw incorporation over a decade,while the SOC stock under MW0 was significantly reduced by 22.9%after the 11 year long-term experiment.Compared to MW_0,straw incorporation significantly increased organic carbon input,and improved the soil aggregate structure and the ratio of dissolved organic carbon(DOC)to particulate organic carbon(POC),but it did not significantly stimulate soil heterotrophic respiration,resulting in the increased SOC accumulation rate and SOC stocks of bulk soil.The increased ratio of DOC to microbial biomass carbon(MBC)enhanced the relative abundances of Acidobacteria and Proteobacteria but inhibited Bacteroidetes and Chloroflexi,and the bacterial relative abundances were the main reasons for the non-significant increase or even decrease in soil heterotrophic respiration with straw incorporation.The SOC stock would reach an equilibrium based on the results of Rothamsted carbon(RothC)model simulations,with a long-term equilibrium value of 18.85 Mg ha^(–1)under MW_(50).Overall,the results of the long-term field experiment(2007–2018)and RothC model simulation suggested that maize–wheat rotation with 50%chopped straw incorporation delivered the largest benefits for the SOC stock in calcareous soils of subtropical mountain landscapes over the long term.
