基于扫描电镜解析毛乌素沙地砒砂岩与沙复配成土的微观结构特征

Analysis of Micro-structure of Composited Soil with Feldspathic Sandstone and Sand Through the Scanning Electronic Microscope in Mu Us Sandy Land Region

砒砂岩与沙复配成土造田与生态建设为毛乌素沙地综合治理提供了新途径,但其微观结构与机理研究较为薄弱.本文利用扫描电镜获得风沙土、砒砂岩、复配土及农田土壤的微观图像,定性揭示其表观差异,并综合运用ImageJ、Photoshop、Nano Measurer等图像处理软件定量刻画不同类型土体的孔隙特征、粒级特征和团聚特征.研究表明:①在微观结构上,复配土兼具砒砂岩与风沙土的部分差别化特性;②复配土平均孔隙占有率达32%,较致密的砒砂岩有所改善;③复配土中0~0.05mm土粒占比由风沙土中的3%提升到41%,粒径组成明显优化;④平均每幅电镜图像中复配土团聚体数量达6.67个,尽管与农田土相比仍有差距,但已具备良性发育的基础;⑤复配土与农田土微观结构趋于相似,但功能特性仍略有差距,作物单产仍略低于当地高产田平均水平.本研究建立的技术方法可以较好地定量刻画土壤微观结构特征,对快速直观地判断、调控与管理土壤状况有积极作用.

The use of composited soil with feldspathic sandstone and sand in reclaiming arable land and ecological preservation-oriented construction provide new method towards the comprehensive consolidation in the Mu Us Sandy Land Region.However,few studies are devoted to the analysis towards reclamation mechanism and micro-structure of the composited soil.This paper contributes to use electronic microscope to retrieve microcosmic image of the aeolian sandy soil,feldspathic sandstone,composited soil and agricultural soil in order to identify their apparent differences.Three image processing software(ImageJ,Photoshop,Nano Measurer)were employed to quantitatively analyze the characterizations of the pore space,granular feature and aggregate composition in different soil.The results show:1)Composited soil with feldspathic sandstone and sand contains the properties of both feldspathic sandstone and sand in terms of micro-structure.2)The composited soil consists of 32%pore space,much higher than that of soft rock(23%).3)The proportion of 0~0.05 mm soil particle in composited soil is 41%,compared to that of 3%in sandy soil,reflecting a much improvement in particle composition.4)Composited soil consists aggregation amounting to 6.67 in SEM images,which is lower than farmland,but higher than that of sand and enables the cultivation.5)Some slight disparities between composited soil and farmland soil can be found in terms of functional characteristics,reflecting in the lower productivity of composited soil compared to farmland.However,the composited soil has entered the trend of improvement.The new methods adopted in this paper enables to have a comprehensive understanding towards the micro-structure of the composited soil,facilitating soil management and efficient usage.