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本研究以关中旱作塿土18年长期肥料定位试验土壤为试材,探讨不同施肥处理对土壤总有机碳的影响。本文涉及的施肥处理包括:(1)对照不施肥(CK);(2)单施氮肥(N);(3)氮钾肥(NK);(4)氮磷肥(NP);(5)磷钾肥(PK);(6)氮磷钾肥(NPK);(7)有机肥+氮磷钾肥(MNPK)。研究结果表明,(1)与对照相比,无论单施NPK化肥还是有机无机肥配施,耕作层土壤总有机碳含量均有不同程度的提高,但有机肥和化肥联合施用效果更好。随时间延长,有机无机肥配施的土壤总有机碳增长率呈递减趋势;(2)长期平衡施肥(NPK处理)有利于保持和提高耕层土壤总有机碳含量,其他不平衡施肥(NP、NK、PK处理)也可以增加土壤总有机碳含量,但长期单施氮肥会导致土壤总有机碳含量降低;(3)有机无机肥配施对提高耕层土壤总有机碳含量效果优于其它处理;不同施肥处理总有机碳含量随土层剖面垂直分布均有下降趋势,在下层土壤中不同施肥处理的总有机碳含量差异不显著。综上可见,长期有机无机肥配施可显著增加土壤有机碳含量,平衡施用无机化肥也能够在一定程度上维持或提高土壤有机碳水平。
In this study, soil samples collected from 18 years of long-term fertilization experiment on Guanzhong dryland were used as test materials to investigate the effects of different fertilization treatments on soil total organic carbon. Fertilization treatments involved in this article include: (1) CK (CK); (2) single N application; (3) N and K fertilizers; (4) N and P fertilizers; (PK); (6) NPK; (7) organic fertilizer + NPK (MNPK). The results showed that: (1) Compared with the control, no matter whether NPK fertilizer or organic-inorganic fertilizer was applied alone, total organic carbon in cultivated soil increased to some extent, but combined application of organic fertilizer and chemical fertilizer was better. (2) Long-term balanced fertilization (NPK) is beneficial to maintain and increase total soil organic carbon in topsoil, and other unbalanced fertilization (NP, NK and PK treatment) could also increase soil total organic carbon content, but long-term single application of nitrogen fertilizer would lead to a decrease of soil total organic carbon content. (3) Organic-inorganic fertilizers had better effect on increasing total organic carbon in topsoil than other treatments . The total organic carbon content of different fertilization treatments decreased with the vertical distribution of soil profile, and there was no significant difference in the total organic carbon content of different fertilization treatments in the lower soil. In conclusion, long-term application of organic-inorganic fertilizers can significantly increase the content of soil organic carbon, and the balanced application of inorganic fertilizers can also maintain or increase the level of soil organic carbon to a certain extent.