生物质炭改良盐渍土CT孔隙图像的多重分形与相对熵特征

The Multifractal and Relative Entropy Characteristics of Pore Structure of CT Images in Biochar-amended Saline Soils

定量化分析土壤结构对于了解土壤的物理、化学和生物过程有至关重要的作用。结合尺度分析理论和图像处理技术可从微观角度阐明土壤结构演变过程,解决生物质炭添加对土壤结构影响的争议问题。本研究以江苏滨海盐渍土为研究对象,设置0%、2%、5%(占0~20 cm表层土壤质量比)3个生物质炭添加水平改良盐渍土。每年在水稻收割后,采用塑料环刀取表层(0~20 cm)原状土,进行Micro-CT扫描获取土壤CT孔隙结构,采用不同的理论方法(多重分形分析和相对熵分析)分析生物质炭改良土壤CT孔隙的复杂尺度行为。结果表明,多重分形分析适合于灰度图像,而相对熵分析适合于二值图像。所有处理的孔隙复杂度逐年增加,生物质炭添加能够加快土壤孔隙结构的发育,孔隙复杂度增加速率更快。在不同生物质炭处理中,2%生物质炭处理的孔隙结构复杂程度最高(△α=0.061,Range△E=0.436),土壤的孔隙结构改善效果最好。高生物质炭的添加量(5%生物质炭处理)减少孔隙结构的复杂度(△α=0.045,Range△E=0.531),降低生物质炭的改良效果。本研究从孔隙微观角度为生物质炭改良孔隙结构提供理论依据。

【Objective】Soil structure is the key to understanding physical,chemical,and biological processes that play a vital role in biodiversity and agricultural productivity.However,due to the mutual influence and simultaneous progress of these process,soil structure evolution has become irregular,unstable,and highly complex.With the development of computer technology on CT scanning images,different scaling and descriptive statistical analysis allow for a better study of soil pore structure or architecture.【Method】Inthis study,the saline/sodic soil in the coastal reclamation area of JiangsuProvince was taken as the object of investigation.Based on multifractal and relative entropy theory,combined with Micro-CT technology,the scaling features of the pore structure of biochar-amended saline soil were revealed.【Result】In this study,the surface soils(0-20 cm)were amended by thoroughly mixing with biochar atthree application rates(0%,2%and 5%by mass of soil)in a completely randomized design.This experiment lasted for four years from 2017 to 2020.To reveal the scaling characteristics of CT pores,two methods were applied:multifractal analysis(MFA)and relative entropy(E).The results showed that different theoretical methods should be used to analyze the complex scaling behavior of soil pores.The multifractal method was suitable for grey images,while the relative entropy method was suitable for binary images.The pore complexity of all treatments increased from one year to the next.Also,the addition of biochar accelerated the developments of soil pore structure and induced a faster rate of increase in pore complexity.Among different biochar treatments,the pore complexity of 2%biochar treatment was the highest(△α=0.061D=,Range△E0.436D=)and the improvement effect was the best.The addition of high biochar(5%biochar treatment)reduced the pore complexity(△α=0.045D=,Range△E0.531D=),reducing the improvement effect of biochar.【Conclusion】This study can provide a theoretical basis for the use of biochar to improve pore structure from a microscopic point of view.