膨润土与秸秆配施对根区土壤有机碳化学结构和酶活性的影响

Effects of combined application of bentonite and straw on organic carbonation structure and enzyme activity of soil in root zone

为揭示膨润土与秸秆配施后土壤有机碳及其化学结构特征,选取黄土高原旱作区3年田间定位试验中的秸秆还田(S)、单施膨润土(B)、膨润土配施秸秆(H)、不施膨润土和秸秆不还田(CK)4个处理,研究膨润土与秸秆配施对根际土壤有机碳含量、有机碳化学结构和酶活性的影响。结果表明:施用膨润土和秸秆均能不同程度提高土壤有机碳含量,其中H处理较CK显著提高了19.65%。与CK相比,仅有H处理显著增加了烷基碳和烷氧碳的相对含量和脂族碳/芳香碳值,分别提高了25.53%、18.00%和50.98%;仅有H处理芳香性显著降低了30.93%;与CK相比,各处理增加了烷基碳/烷氧碳值,增幅为5.26%~17.54%,差异不显著;各处理降低了羧基碳和芳香碳相对含量,降幅分别为24.50%~38.19%和1.29%~21.97%,差异不显著。与CK相比,S、B和H处理蔗糖酶活性显著提高12.63%~33.16%;β-葡萄糖苷酶活性显著提高10.72%~45.56%;锰过氧化物酶活性显著提高25.10%~70.98%。相关性分析表明,土壤蔗糖酶、β-葡萄糖苷酶和锰过氧化物酶活性均与有机碳含量、烷基碳含量和烷基碳/烷氧碳值呈正相关,与羧基碳和芳香性呈负相关。综上所述,膨润土与秸秆配施能够提高土壤有机碳含量,提高土壤酶活性,增加活性有机碳含量,使土壤有机碳分子活化,有利于改善黄土高原旱作区土壤状况。

In order to reveal the characteristics of soil organic carbon and its chemical structure after combined application of bentonite and straw,this study selected four treatments from a 3-year field positioning experiment in the dryland area of the Loess Plateau,including straw returning(S),single application of bentonite(B),bentonite with straw(H),no application of bentonite and straw without returning(CK),to study the effects of bentonite and straw combination on the organic carbon content,organic carbon chemical structure and enzyme activity of the root zone soil.The results showed that both bentonite and straw application increased the soil organic carbon content to varying degrees,with H treatment significantly increasing by 19.65%,compared to CK treatment.Compared with CK treatment,only H treatment significantly increased the relative content of alkyl carbon and alkoxy carbon,as well as the aliphatic carbon/aromatic carbon ratio,by 25.53%,18.00%and 50.98%,respectively;Only H treatment significantly reduced aromaticity by 30.93%.Compared with CK,each treatment increased the alkyl carbon/alkoxy carbon ratio,with an increase of 5.26%-17.54%,and the difference was not significant;Each treatment reduced the relative content of carboxyl carbon and aromatic carbon by 24.50%-38.19%and 1.29%-21.97%,respectively,with no significant difference.Compared with CK,the sucrase activity of S,B and H treatments was significantly increased by 12.63%-33.16%,β-glucosidase activity was significantly increased by 10.72%-45.56%,and manganese peroxidase activity was significantly increased by 25.10%-70.98%.Correlation analysis showed that soil sucrase,β-glucosidase and manganese peroxidase activities were positively correlated with organic carbon content,alkyl carbon content and alkyl carbon/alkoxy carbon ratio,but negatively correlated with carboxyl carbon and aromaticity.In summary,the combination application of bentonite and straw can increase soil organic carbon content,increase soil enzyme activity,increase active organic carbon content,activate soil organic carbon molecules,and promote good soil improvement in the arid areas of the Loess Plateau.