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Dynamic Oxygen and Carbon Dioxide Exchange between Soil and Atmosphere: II. Model Simulations
Author(s) -
Ouyang Y.,
Boersma L.
Publication year - 1992
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1992.03615995005600060007x
Subject(s) - soil water , carbon dioxide , environmental science , soil science , atmosphere (unit) , infiltration (hvac) , aeration , soil respiration , sink (geography) , canopy , dns root zone , environmental chemistry , chemistry , atmospheric sciences , hydrology (agriculture) , materials science , geology , ecology , physics , cartography , organic chemistry , biology , composite material , thermodynamics , geography , geotechnical engineering
An important general objective for modeling gaseous transport through unsaturated soils is to provide better understanding of gas exchange between the terrestrial ecosystem and the atmosphere. A more specific objective is the evaluation of problems of soil aeration. We present sensitivity analyses of a mathematical model developed for the dynamic exchange of O 2 and CO 2 between soil and atmosphere. We also present simulations to evaluate changes in concentrations during cycles of infiltration, evaporation, and redistribution during which simultaneous transport of water, heat, O 2 , and CO 2 was involved. Simulation was also used to evaluate possible effects of O 2 and CO 2 concentrations on the rate of root growth; effects of a compacted layer on the simultaneous transport of water, O 2 , and CO 2 ; effect of the presence of a crop canopy on concentrations of O 2 and CO 2 in the soil; and an evaluation of possible nonideal behavior of CO 2 molecules in the gas phase of the soil. Results emphasize the important effects of rainfall, evaporation, and root respiration on O 2 and CO 2 concentrations in the soil. Simulations show that root growth below a compacted soil layer may be restricted by low O 2 concentrations resulting from limited diffusion through the compacted layer. The presence of a crop canopy has a decisive effect on concentrations of O 2 and CO 2 at the soil surface, thereby affecting the concentrations of those gases in the root zone.