不同秸秆还田方式对土壤腐殖质组成的影响

Effects of Different Ways of Corn Stover Returning on Soil Humus Composition

针对东北黑土肥力下降和秸秆未能合理利用问题,研究了玉米秸秆不同还田方式对黑土土壤有机碳和腐殖质组成的影响。试验共设置未施用秸秆(ck)、秸秆浅施(CS2)、秸秆深还(CS3)、秸秆与土壤混合浅施(CS4)、秸秆与土壤混合深还(CS5)5种处理。使用腐殖质组成修改法提取水溶性物质(WSS)、富里酸(Fulvic acid,FA)、胡敏酸(Humic acid,HA)和胡敏素(Humin,HM)。结果表明:秸秆还田后,各处理SOC、HAC、PQ值以及HA的ΔlgK值均提高。与ck相比,玉米秸秆与0~20 cm土壤均匀混合后浅施(CS4)显著提高了表层土壤速效养分(N、P、K)含量,其中碱解氮含量增加了14.21 mg/kg,有效磷含量增加了14.99 mg/kg,速效钾含量增加了42.91 mg/kg;玉米秸秆与20~40 cm土壤均匀混合后深还(CS5)显著提高了亚表层土壤速效养分(N、P、K)含量,其中碱解氮含量增加了21.51 mg/kg,有效磷含量增加了13.30 mg/kg,速效钾含量增加了39.09 mg/kg。与ck相比,各处理各层土壤腐殖质组成碳的含量均有不同程度上升,其中CS4处理HA、FA、HM有机碳含量与ck相比分别上升33.82%、9.38%、31.15%;CS5处理HA、FA、HM有机碳含量与ck相比分别上升35.48%、17.51%、19.80%。秸秆还田后各处理PQ值均有不同程度上升,与ck相比,表层土壤中CS4处理PQ值显著上升,从63.91%上升到68.42%。与ck相比,全量秸秆深还(CS)处理显著提高了胡敏酸和富里酸色调系数ΔlgK的值,表层和亚表层胡敏酸的ΔlgK分别提高了7.19%和12.48%,富里酸的ΔlgK分别提高了4.19%和10.18%。说明秸秆还田可以提高黑土土壤腐殖化程度,使土壤HA结构变得简单。

Considering the decline of black soil fertility in Northeast China and the failure of rational utilization of corn stover,the effects of different returning methods of corn stover on soil organic carbon and humus composition in black soil were studied.Five treatments were set as follows:ck(no corn stover incorporated),CS2(corn stover incorporated to shallow layer),CS3(corn stover deep incorporation),CS4(corn stover and shallow layer soil evenly mixed to surface soil),and CS5(corn stover and deep layer soil evenly mixed to deep soil).Fulvic acid(FA),humic acid(HA) and humin(HM) were extracted by the modified humus component method.Compared with CK,the content of available nutrients(N,P,K) in surface soil was increased by 14.21 mg/kg,14.99 mg/kg and 42.91 mg/kg in CS4.The content of available nutrients(N,P,K) in subsurface soil was increased by 21.51 mg/kg of alkali-hydrolyzed nitrogen,13.30 mg/kg of available phosphorus and 39.09 mg/kg of available potassium after corn straw was mixed with 20-40 cm soil.Compared with ck,the content of soil humus composition carbon in each layer of each treatment increased to varying degrees.The content of HA,FA and HM organic carbon in CS4 treatment increased by 33.82%,9.38% and 31.15%,respectively,compared with ck.The HA,FA and HM organic carbon contents of CS5 were 35.48%,17.51% and 19.80% higher than those of ck,respectively.After straw returning to the field,PQ value of each treatment increased to varying degrees.Compared with ck,PQ value of CS4 treatment in topsoil increased significantly,from 63.91% to 68.42%.Compared with ck,the tonal coefficient ΔlgK of humic acid and fulferic acid was significantly increased by CS treatment.The ΔlgK of humic acid in surface and subsurface layer was increased by 7.19% and 12.48%,and the ΔlgK of fulferic acid was increased by 4.19% and 10.18%,respectively.The results showed that SOC,carbon content of HA,PQ value,and ΔlogK value of HA and FA were all increased after corn stover was returned to the field.The results show that corn stover returning can improve humification degree of black soil and make humus structure simple.