应用DNDC模型分析东北黑土有机碳演变规律及其与作物产量之间的协同关系

【目的】探索长期不同施肥方式下土壤有机碳的动态变化及其与作物产量之间的耦合关系，以期为东北地区黑土耕地资源的持续利用与管理提供科学依据。【方法】基于黑土区国家土壤肥力与肥料效益监测网站公主岭监测基地的23年长期定位试验数据，选取不施肥（CK）、单施氮磷钾肥（NPK）、无机肥配施低量有机肥（NPKM1）、1.5倍的无机肥配施低量有机肥[1.5（NPK）M1]、无机肥配施高量有机肥（NPKM2）和无机肥配施秸秆（NPKS）6个处理进行土壤有机碳和产量的分析，将数据用于DNDC模型验证，并对6种施肥处理在未来气候下（40 a）黑土有机碳的演变进行模拟。【结果】试验监测结果表明:从1990~2012年的土壤有机碳数据分析得出，长期不施肥土壤有机碳从12.49 g/kg以年均0.69%的速率下降，有机无机配施可以提升土壤有机碳含量。DNDC验证结果如下:DNDC验证土壤有机碳时各处理的相对均方根误差（RMSE）为14.98%~37.91%，验证作物产量时各处理的RMSE为8.28%~11.19%，说明模型能够基本反映长期不同施肥下的作物产量和土壤有机碳的变化。未来气候下的模拟结果表明:CK和NPK处理土壤有机碳在未来40年里分别下降16.67%和11.21%。而3个化肥有机肥配施处理在未来40年呈稳定增长态势，NPKM1、1.5（NPK）M1和NPKM2处理的土壤有机碳将分别增加13.65%、15.74%和15.84%，以1.5（NPK）M1增势最为显著。NPKS处理的有机碳相对初始略有增加。当施氮量从160 kg/hm2增至320 kg/hm2时，土壤有机碳每增加1.00 g/kg，作物产量的增加量从44.48 kg/hm2下降至15.95 kg/hm2。【结论】从长期实测数据的分析和DNDC模型模拟得出，实施秸秆还田和有机肥配施无机肥能有效持续增加SOC含量，并能获得较高的作物产量。在施氮量160~320 kg/hm2水平下，作物产量随着土壤有机碳含量的增加而升高，且土壤有机碳含量对产量的提升幅度随着施氮量的升高而降低。

Using DNDC model to simulate black soil organic carbon dynamics as well as its coordinate relationship with crop yield

[Objectives] The effects of long-term fertilization on black soil organic carbon content and crop yield were researched and stimulated using the DNDC model in Northeast China,which will provide a scientific basis for the sustainable use of the arable land resources and scientific managements in the region.[Methods] Data were collected from the long-term experiments carried out in National Fertility Monitoring Net in Gongzhuling City,Jilin Province.Six of the fertilization treatments were chosen to analyze the changes in soil organic carbon (SOC) and crop yield,including:no fertilizer (CK),only chemical fertilizer application (NPK),combining chemical and low levels of organic manure (NPKM1),1.5 times of the amount of inorganic and organic fertilizer ofNPKM1 (1.5(NPK)M1),combining chemical and high amount of organic manure (NPKM2),inorganic fertilizer plus straw (NPKS),and the DNDC model was validated using these data.The model was used to imitate the variation of SOC in the coming 40 years under the six fertilization treatments.[Results] The root mean square error (RMSE) of SOC in treatment was in range of 14.98％-37.91％,those of crop yields were in range of 8.28％-11.19％,which suggested that the simulated values were consistent with the observed values,so the DNDC model was reliable for the simulation purpose in the studied area.The simulated results indicated that the SOC in CK and NPK treatments would drop by 16.67％ and 11.21％ respectively,and those in NPKM1,NPKM2 and 1.5(NPK)M1 treatments would be steadily increasing in the next 40 years,with the most significant growth in treatment of 1.5 (NPK)M1.The SOC contents in NPKM1,1.5 (NPK)M1 and NPKM2 will be increased by 13.65％,15.74％,15.84％ from 2010 to 2050 respectively.The measured SOC content in NPKS treatment had slightly increased since the beginning of the experiment.When the nitrogen application was increased from 160 kg/hm2 to 320 kg/hm2,the SOC would simultaneously increase in magnitude of 1.00 g/kg,and the crop yields increase would drop from 44.48 kg/hm2 to 15.95 kg/hm2.[Conclusions] Analyzation of data from the measured and DNDC model simulated,combined application of straw,manure and inorganic fertilizer will be effective in increasing the content of soil organic carbon continuously,and leading to steadily increase of crop yields at the same time.When the nitrogen application rate is between 160 kg/hm2-320 kg/hm2,the crop yields will keep increasing with the increasing of soil organic carbon content,and the hoist scope of SOC in increasing crop yield would fall with the increase of nitrogen application rate.