Research progress in influencing factors and measuring methods of three-dimensional characteristics of soil macropores

Macropore is the main channel for preferential flow, therefore it largely impacts the transportation of water, air, and chemical materials in soil. Recently, it has become a focus of interest for quantitative analysis and influencing factors of three-dimensional(3D) morphological characteristics of soil macropores, since it could provide fundamental explanations for water soil movement patterns and groundwater pollution assessment. This paper examines state-of-the-art research development regarding 3D morphological characteristics of soil macropore by revisiting the concept (macropore volume, surface area, length, number, tortuosity, inclination angle, path number, macropore diameter, node, connectivity, roundness, etc.), quantitative measurements and software (Avizo 9.0, VG Studio MAX 2.2, Arc/Info 10.0, Image J, etc.) and impact factors (root system, soil animal, alternation of dry wet and freeze-thaw, human factors, etc.) of soil macropore characteristics. On the basis of summarizing the current research status, this paper summarizes the relevant research conclusions, and also proposes the direction of future work by reviewing current work.