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Article

Soil-Gas Diffusivity-Based Characterization of Variably Saturated Agricultural Topsoils

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Department of Civil Engineering, Faculty of Engineering, University of Peradeniya, Peradeniya 20400, Sri Lanka
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College of Pastoral Agriculture Science and Technology, National Field Scientific Observation and Research Station of Grassland Agro-Ecosystems in Gansu Qingyang, The State Key Laboratory of Grassland Agro-Ecosystems of Lanzhou University, Lanzhou 730020, China
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State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A&F University, Xianyang 712100, China
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Department of Soil and Physical Sciences, Lincoln University, P.O. Box 85084, Lincoln 7647, New Zealand
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Department of Geosciences and Natural Resource Management, Center for Permafrost (CENPERM), University of Copenhagen, Øster Voldgade 10, DK-1350 Copenhagen, Denmark
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Department of Civil and Environmental Engineering, Southern Methodist University, Dallas, TX 75205, USA
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Author to whom correspondence should be addressed.
Academic Editor: Behzad Ghanbarian
Water 2022, 14(18), 2900; https://doi.org/10.3390/w14182900
Received: 26 August 2022 / Revised: 8 September 2022 / Accepted: 14 September 2022 / Published: 16 September 2022
(This article belongs to the Section Soil and Water)
Soil-gas diffusivity and its variation with soil moisture plays a fundamental role in diffusion-controlled migration of climate-impact gases from different terrestrial agroecosystems including cultivated soils and managed pasture systems. The wide contrast in soil texture and structure (e.g., density, soil aggregation) in agriculture topsoils (0–10 cm) makes it challenging for soil-gas diffusivity predictive models to make accurate predictions across different moisture conditions. This study characterized gas diffusivity and gas-phase tortuosity in soils sampled from managed pasture and cultivated sites in Sri Lanka at 0–10 cm depth, together with selected soil-gas diffusivity data from the literature. Soil-gas diffusivity was measured using a one-chamber diffusion apparatus using N2 and O2 as experimental gases. The measured diffusivity, together with literature data representing both intact and repacked soils, were tested against five existing widely known gas diffusivity predictive models. The tested models tended to mischaracterize the two-region behavior in some of the aggregated soils, suggesting the need of soil-specific diffusivity models to better describe gas diffusivity in agricultural soils. We suggested a new parametric two-region model, developed in line with literature-based models, to represent both unimodal and bimodal/two-region behavior of selected soils. The new model statistically outperformed the existing predictive models for both intact and repacked soils and, hence, demonstrated its applicability to better characterize site-specific greenhouse gas emissions under different soil water regimes. View Full-Text
Keywords: agricultural topsoils; soil-gas diffusivity; gas phase tortuosity; soil-moisture effects; predictive–descriptive models agricultural topsoils; soil-gas diffusivity; gas phase tortuosity; soil-moisture effects; predictive–descriptive models
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MDPI and ACS Style

Abeysinghe, A.M.S.N.; Lakshani, M.M.T.; Amarasinghe, U.D.H.N.; Li, Y.; Deepagoda, T.K.K.C.; Fu, W.; Fan, J.; Yang, T.; Ma, X.; Clough, T.; Elberling, B.; Smits, K. Soil-Gas Diffusivity-Based Characterization of Variably Saturated Agricultural Topsoils. Water 2022, 14, 2900. https://doi.org/10.3390/w14182900

AMA Style

Abeysinghe AMSN, Lakshani MMT, Amarasinghe UDHN, Li Y, Deepagoda TKKC, Fu W, Fan J, Yang T, Ma X, Clough T, Elberling B, Smits K. Soil-Gas Diffusivity-Based Characterization of Variably Saturated Agricultural Topsoils. Water. 2022; 14(18):2900. https://doi.org/10.3390/w14182900

Chicago/Turabian Style

Abeysinghe, A. M. S. N., M. M. T. Lakshani, U. D. H. N. Amarasinghe, Yuan Li, T. K. K. Chamindu Deepagoda, Wei Fu, Jun Fan, Ting Yang, Xiaoyi Ma, Tim Clough, Bo Elberling, and Kathleen Smits. 2022. "Soil-Gas Diffusivity-Based Characterization of Variably Saturated Agricultural Topsoils" Water 14, no. 18: 2900. https://doi.org/10.3390/w14182900

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