长期施肥对旱作塿土总有机碳的影响研究

Effects of long-term fertilization on total organic carbon of Lou soil under dryland farming

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。

The effects of fertilizer management regimes on soil total organic carbon(TOC)were investigated based on the 18-year long-term experiment on Lou soil in Guanzhong Plain,Shaanxi province,China.The fertilizer management regimes included(1)control without fertilizer(CK);(2)application of nitrogen(N);(3)nitrogen and potassium(NK);(4)nitrogen and phosphorus(NP);(5)phosphorus and potassium(PK);(6)mixed-application of chemical fertilizers(NPK);(7)application of chemical fertilizers plus dairy manure(MNPK).The results showed that(1)the TOC content increased in varying degrees relative to the control treatment in plough layer under treatments of NPK and MNPK,nevertheless the effect of MNPK treatment was more significant than that of the NPK treatment.However,the increment of TOC content decreased in MNPK treatment with time.(2)The long-term application of balanced fertilization(NPK)helped maintain and improved the TOC content in the plough layer.Other unbalanced fertilizations(NP,PK and NK)could slightly increase the content of soil TOC in plough layer,while the soil TOC content decreased under the N treatment.(3)The effect of MNPK for improving soil TOC content was superior to the other treatments.The soil TOC content decreased with the increasing of soil depth under all the treatments,while no significant differences in soil TOC content were observed in subsurface layers among treatments.It concluded that long-term application of chemical fertilizers plus dairy manure could improve soil fertility status and increase the content of soil total organic carbon,application of balanced chemical fertilizers,in a certain extent,can also maintain the content of soil total organic carbon.