TY - JOUR
T1 - Linking saturated hydraulic conductivity and air permeability to the characteristics of biopores derived from X-ray computed tomography
AU - Zhang, Zhongbin
AU - Liu, Kailou
AU - Zhou, Hu
AU - Lin, Henry
AU - Li, Daming
AU - Peng, Xinhua
N1 - Funding Information:
The National Natural Science Foundation of China (NSFC 41771264 , 41401245 and 4157113005 3) and the Innovation Program of the Institute of Soil Science CAS, China (No. ISSASIP1610 ) funded this study. The authors acknowledge the staff at the Jiangxi Institute of Red Soil who conducted and maintained the long-term field experiment.
Funding Information:
The National Natural Science Foundation of China (NSFC 41771264, 41401245 and 41571130053) and the Innovation Program of the Institute of Soil Science CAS, China (No. ISSASIP1610) funded this study. The authors acknowledge the staff at the Jiangxi Institute of Red Soil who conducted and maintained the long-term field experiment.
Publisher Copyright:
© 2019 Elsevier B.V.
Copyright:
Copyright 2019 Elsevier B.V., All rights reserved.
PY - 2019/4
Y1 - 2019/4
N2 - The different types of soil macropores (e.g., biopores and non-biopores) vary in the conductivity of water or air due to the difference in the 3D pore characteristics. The objectives of this study were to reveal which types of macropores and which macropore characteristics played the most important roles in regulating water or air flow. Intact soil columns sampled from the subsoil of a long-term fertilization experiment were scanned by medical X-ray computed tomography (CT), and subsequently, saturated hydraulic conductivity (K s ) and air permeability at −12 cm water potential (K a12 ) were measured. The 3D characteristics of macropores were then analyzed with image analysis. The biopores and the percolating biopores that connected the top and the bottom of a soil column were separated for the biopore-dominated samples (with percolating biopores) and their 3D characteristics were also quantified. Our results showed that the mean macropore diameter of the limiting layer (MDLL) presented the best relationships with K s and K a12 compared with the other macropore characteristics for all the samples. The biopores and percolating biopores contributed 27.8–74.5% and 3.26–64.4% of the volume of total macropores, respectively, for the biopore-dominated samples. The hydraulic radius, mean diameter, compactness, global and local connectivities, and MDLL of biopores, especially those of percolating biopores, were generally larger than those of total macropores. The global connectivity (Γ) of biopores performed very well for estimating K s and K a12 . The MDLL of percolating biopores could predict K s much better than the MDLL of biopores and total macropores. Moreover, the performance of MDLL for estimating K a12 was as good as the MDLL of biopores but was much better than the MDLL of total macropores. The findings of this study reveal that the MDLL is a more useful parameter in estimating saturated hydraulic conductivity and air permeability at low water potential than the other CT-derived pore characteristics.
AB - The different types of soil macropores (e.g., biopores and non-biopores) vary in the conductivity of water or air due to the difference in the 3D pore characteristics. The objectives of this study were to reveal which types of macropores and which macropore characteristics played the most important roles in regulating water or air flow. Intact soil columns sampled from the subsoil of a long-term fertilization experiment were scanned by medical X-ray computed tomography (CT), and subsequently, saturated hydraulic conductivity (K s ) and air permeability at −12 cm water potential (K a12 ) were measured. The 3D characteristics of macropores were then analyzed with image analysis. The biopores and the percolating biopores that connected the top and the bottom of a soil column were separated for the biopore-dominated samples (with percolating biopores) and their 3D characteristics were also quantified. Our results showed that the mean macropore diameter of the limiting layer (MDLL) presented the best relationships with K s and K a12 compared with the other macropore characteristics for all the samples. The biopores and percolating biopores contributed 27.8–74.5% and 3.26–64.4% of the volume of total macropores, respectively, for the biopore-dominated samples. The hydraulic radius, mean diameter, compactness, global and local connectivities, and MDLL of biopores, especially those of percolating biopores, were generally larger than those of total macropores. The global connectivity (Γ) of biopores performed very well for estimating K s and K a12 . The MDLL of percolating biopores could predict K s much better than the MDLL of biopores and total macropores. Moreover, the performance of MDLL for estimating K a12 was as good as the MDLL of biopores but was much better than the MDLL of total macropores. The findings of this study reveal that the MDLL is a more useful parameter in estimating saturated hydraulic conductivity and air permeability at low water potential than the other CT-derived pore characteristics.
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U2 - 10.1016/j.jhydrol.2019.01.041
DO - 10.1016/j.jhydrol.2019.01.041
M3 - Article
AN - SCOPUS:85061136537
VL - 571
SP - 1
EP - 10
JO - Journal of Hydrology
JF - Journal of Hydrology
SN - 0022-1694
ER -