TY - JOUR

T1 - Soil-Gas Diffusivity-Based Characterization of Variably Saturated Agricultural Topsoils

AU - Abeysinghe, A. M. S. N.

AU - Lakshani, M. M. T.

AU - Amarasinghe, U. D. H. N.

AU - Li, Yuan

AU - Deepagoda, T. K. K. Chamindu

AU - Fu, Wei

AU - Fan, Jun

AU - Yang, Ting

AU - Ma, Xiaoyi

AU - Clough, Tim

AU - Elberling, Bo

AU - Smits, Kathleen

N1 - CENPERMOA[2022]

PY - 2022

Y1 - 2022

N2 - 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 N-2 and O-2 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.

AB - 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 N-2 and O-2 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.

KW - agricultural topsoils

KW - soil-gas diffusivity

KW - gas phase tortuosity

KW - soil-moisture effects

KW - predictive-descriptive models

KW - WATER

KW - MODEL

U2 - 10.3390/w14182900

DO - 10.3390/w14182900

M3 - Journal article

VL - 14

JO - Water

JF - Water

SN - 1462-897X

IS - 18

M1 - 2900

ER -