基于DNDC模型气候变化下长期施肥对紫色土区玉米产量和土壤有机碳影响的分析

Effect analysis of long-term fertilization on summer corn yield and soil organic carbon in purple soil areas under climate change based on DNDC model

  • 摘要: 农田土壤有机碳(soil organic carbon, SOC)储量的动态变化与施肥策略及气候变化密切相关, 为探究在气候变化下增产固碳的施肥策略, 以紫色土区玉米农田为研究对象, 利用长期定位监测试验对反硝化-分解模型(Denitrification-Decomposition, DNDC)进行校正与验证, 并利用校正后的DNDC模型与CMIP6模式未来情景气候数据结合, 分析了基准、SSP2-4.5和SSP5-8.5 3种未来情景下不施肥(CK)、有机肥化肥配施(T1)、常量单施化肥(T2)和增量单施化肥(T3) 4种施肥措施对玉米产量和SOC储量的影响。结果表明, 研究区在两种SSP情景下降雨量和温度随着年代增加均呈现上升趋势, 且SSP5-8.5情景降雨量和温度的上升趋势更大; 各处理产量和表层SOC含量实测值和模拟值的平均偏差误差(MBE)趋近于0, 标准均方根误差(NRMSE)为0.09~0.19, 决定系数(R2)为0.74~0.98, 校正后的DNDC模型模拟效果较好, 能够用于紫色土区玉米产量和SOC的模拟。在T1处理下, 各未来情景下SOC储量无显著差异, 气候变化对施用有机肥的玉米产量和SOC储量影响较小; 与基准情景相比, SSP2-4.5情景和SSP5-8.5情景能够显著提高不施肥处理的玉米产量, 但会显著减少单施化肥处理的玉米产量。CK、T2、T3处理下各情景SOC储量随年代均呈降低趋势, 在T1处理下各情景SOC储量随年代变化均呈现升高的趋势; 2100年各处理SOC储量表现为T1>T3≈T2>CK。不同施肥措施下, 2100年SSP5-8.5情景的SOC损失量均高于SSP2-4.5情景, 高排放情景会导致更多SOC损失。在未来气候变化下, 常规施肥模式虽然能够保证作物稳产, 但不利于农田固碳, 而有机肥化肥配施是紫色土耕地实现固碳增产较为适宜的施肥管理模式。

     

    Abstract: The dynamic changes in soil organic carbon (SOC) storage in farmland are closely related to fertilization strategies and climate change. In order to explore fertilization strategies for increasing yield and sequestering carbon under climate change, this study takes summer corn farmland in purple soil areas as the research object. The DNDC model is calibrated and validated using long-term positioning monitoring experiments, and the calibrated DNDC model is combined with future climate data from CMIP6 model to study the effects of different fertilization measures on summer corn yield and SOC under three future scenarios (baseline scenario, SSP2-4.5 scenario, and SSP5-8.5 scenario). The results shows that in both SSP scenarios, the decrease in rainfall and temperature in the study area showed an upward trend with increasing age, and SSP5-8.5 scenario showed a greater upward trend in rainfall and temperature; The calibrated DNDC model has good simulation performance and can be applied to simulate summer corn yield and SOC in purple soil areas. Under T1 treatment, there was no significant difference in SOC storage under various future scenarios, and climate change had a relatively small impact on the yield and SOC storage of organic fertilizer application; Compared with the baseline scenario, SSP2-4.5 and SSP5-8.5 scenarios can significantly increase the yield of summer corn without fertilization treatment, but significantly reduce the yield of summer corn treated with chemical fertilizer alone; Under CK, T2, and T3 treatments, the SOC reserves of each scenario showed a decreasing trend with age, while under T1 treatment, the organic carbon reserves of each scenario showed an increasing trend with age. By 2100, the SOC reserves of each treatment showed a trend of T1>T3≈T2>CK; Under different fertilization measures, the SOC loss in SSP5-8.5 scenario by 2100 is higher than that in SSP2-4.5 scenario, and high emission scenario will lead to more SOC loss. Research has found that under future climate change, although conventional fertilization methods can ensure stable crop yields, they are not conducive to carbon sequestration in farmland. The combination of organic and chemical fertilizers is a more suitable fertilization management mode for achieving carbon sequestration and yield increase in purple soil farmland.

     

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