膨润土对科尔沁沙地土壤肥力和活性有机碳的影响

Effect of bentonite on soil fertility and active organic carbon in Horqin sandy land

膨润土比表面积大,吸附能力强,具有良好的保水保肥和离子交换能力。不同类型膨润土对沙地土壤肥力和活性有机碳积累的影响尚不清楚。文中以科尔沁沙地土壤为基质,在施入化肥和草炭基础上,对钠基膨润土和钙基膨润土分别设置3个施加量,以草地早熟禾(Poa pratensis L.)为受试植物进行盆栽实验,研究不同膨润土类型和施加量条件下土壤肥力和活性有机碳的变化。结果表明,与对照相比各处理均显著提高了土壤综合肥力指数(IFI)、总有机碳含量和活性有机碳各组分含量,其中施加量为3.0kg/m^(2)时效果最佳。相关性分析和冗余分析表明,施加3.0kg/m^(2)的钠基膨润土和3.0kg/m^(2)、4.5kg/m^(2)的钙基膨润土与土壤IFI、总有机碳及各活性有机碳组分含量显著正相关,总有机碳(尤其是微生物量碳)与IFI极显著正相关。上述结果表明,膨润土能够显著促进土壤活性碳积累、提高土壤肥力,进而影响土壤微生态环境和碳循环;膨润土施加量是沙地土壤生态修复的关键调节因子,而膨润土类型不是重要决定因素。

Bentonite has a large specific surface area and strong adsorption capacity,as so as has excellent water and fertilizer retaining and ion exchange capacity.The effect of bentonite types on the accumulation of active organic carbon and fertility in wind-sand soil is not clear.In this paper,in order to study the changes of soil fertility and active organic carbon components under different types and application amounts of bentonite,a pot experiment was conducted by using Poa pratensis L.as plant material,and Horqin sandy soils as the substrate,and then sodium-based bentonite and calcium-based bentonite in three application amounts were added on the basis of application of fertilizer and charcoal.The results showed that compared with control,bentonite with different application types and amounts significantly improved the soil integrated fertility index(IFI),total organic carbon content and contents of various components of active organic carbon,of which the best effect was achieved when the amount of bentonite applied was 3.Okg/m².Correlation and redundancy analyses showed that the application of 3.Okg/m²sodium-based bentonite and 3.Okg/m²,4.5kg/m²calcium-based bentonite,is significantly positively correlated with soil IFI,total organic carbon content,and contents of various active organic carbon.There is a highly significant positive correlation between total organic carbon(especially microbial biomass carbon)and IFI.The above results indicate that bentonite can significantly promote the accumulation of active carbon in soil,improve soil fertility,and there by affect soil microecological environment and carbon cycling.The amount of bentonite is a key regulatory factor for ecological restoration of sandy soil,while the type of bentonite is not an important determining factor.