The Phaeozem region is an important grain production base in China and soil fertility has declined under long-term cultivation. Studying soil organic carbon (SOC) change in the upland phaeozem of Northeast China under different tillage modes has great theoretical and practical significance for reducing greenhouse gases emissions, increasing soil carbon stocks, and ensuring food security. This study applied the DAYCENT model to simulate six long-term experimental sites in the phaeozem region, and through calibration and validation analysis, it concluded that the DAYCENT model could effectively simulate the dynamic change of SOC in the upland phaeozems; hence, the relevant parameters of each site were determined. Under future climate scenarios (Representative Concentration Pathway 4.5, RCP 4.5), SOC change in agricultural soils (0–20 cm topsoil) of four different management scenarios (fertilizer application, manure amendment, straw return, no-tillage) was simulated. The overall simulated trend was no-tillage > straw return > manure amendment > fertilizer application. Fertilizer had no evident effect on increasing SOC, but the effect would be better if combined with manure; both straw return and no-tillage had the general effect of improving SOC and the simulated values rose rapidly with a large increasing rate within a short period; however, the increasing rate became gentle after 2050, reached a relatively stable level after 2080, then gradually reached carbon saturation. Untill 2100, the SOC content of each site reached a relatively higher level by adopting the no-tillage treatment, where the SOC contents of Harbin, Hailun, Nehe, Dehui, Gongzhuling and Lishu were 2.36 g/100 g, 2.81 g/100 g, 2.22 g/100 g, 2.38 g/100 g, 1.97 g/100 g and 2.01 g/100 g, respectively. The SOC contents increased by 52.47% when compared with the initial value, and the simulated average annual increase of SOC for 84 years was 0.0082 g/100 g.
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机译：辉县地区是中国重要的粮食生产基地，长期耕作后土壤肥力下降。研究不同耕作方式下东北旱地土壤有机碳的变化对减少温室气体排放，增加土壤碳储量和确保粮食安全具有重要的理论和实践意义。本研究应用DAYCENT模型模拟了Phasezem区域的6个长期实验点，并通过标定和验证分析得出结论，DAYCENT模型可以有效地模拟陆地Phasezems中SOC的动态变化。因此，确定了每个站点的相关参数。在未来的气候情景下（代表性浓度途径4.5，RCP 4.5），模拟了四种不同管理情景（施肥，改良肥料，秸秆还田，免耕）的农业土壤（0-20厘米表土）中的有机碳变化。总体模拟趋势为免耕>秸秆还田>肥料改良>施肥。肥料对增加SOC没有明显作用，但与肥料结合使用效果会更好。秸秆还田和免耕均具有改善土壤有机碳的总体效果，且模拟值在短时间内迅速上升，并以较大幅度增加。但是，到2050年以后，碳的增长速度变得平缓，到2080年达到了相对稳定的水平，然后逐渐达到碳饱和。直到2100年，通过免耕处理，每个站点的SOC含量都达到了相对较高的水平，哈尔滨，海伦，讷河，德惠，公主岭和梨树的SOC含量分别为2.36 g / 100 g，2.81 g / 100 g ，2.22 g / 100 g，2.38 g / 100 g，1.97 g / 100 g和2.01 g / 100 g。与初始值相比，SOC含量增加了52.47％，并且模拟的84年SOC的年均增长为0.0082 g / 100 g。
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