Several models predict soil pore space indices (the relative gas diffusion coefficient, Ds/Do and the pore tortuosity, t), but information is lacking on which models predicted indices better relate to soil processes. We compared pore space indices′ predictive models based on air-filled porosity (fa) alone vs. models using air-filled porosity and total pore space (Φ) (fa Φ). We also assessed the relationships between these indices and CO2 and N2O. The study was conducted from 2011 to 2014 on a silt loam soil at Lincoln University. Soil samples were collected at 0-10 and 10-20 cm depth and oven dried at 105 °C for 72 h. After drying, fa and Φ were calculated and later used in models for predicting Ds/Do and t. CO2 and N2O were measured with a Shimadzu gas chromatograph (GC) and a photoacoustic gas analyzer (PSA). Results showed that Ds/Do predicted using fa alone (Marshall and Buckingham) was higher as compared with values predicted with models based on fa Φ (Sallam et al., Millington, and Jin and Jury) (P < 0.001). However, values of t predicted with models based on fa alone were lowest (P < 0.001). CO2 and N2O measured with GC better related with Ds/Do and t.
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16 June 2016
Comparison of models for predicting pore space indices and their relationships with CO2 and N2O fluxes in a corn—soybean field
Dinesh Panday,
Nsalambi V. Nkongolo
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Canadian Journal of Soil Science
Vol. 96 • No. 3
Sep 2016
Vol. 96 • No. 3
Sep 2016
coefficient de diffusion des gaz
diffusivity models
émissions de gaz à effet de serre
facteur de tortuosité des pores
gas diffusion coefficient
greenhouse gases emissions
modèles de diffusivité