HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Grant, R. F. Articles by Rochette, P. Search for Related Content PubMed Articles by Grant, R. F. Articles by Rochette, P. Agricola Articles by Grant, R. F. Articles by Rochette, P.

Soil Microbial Respiration at Different Water Potentials and Temperatures: Theory and Mathematical Modeling

Dep. of Soil Science, Univ. of Alberta, Edmonton, Alberta, Canada T6G 2E3 and Centre for Land and Biological Resources Research (CLBRR), Agriculture Canada, Ottawa, Ontario, Canada

* Corresponding author (rgrant.gpu.srv.ualberta.ca).

ABSTRACT

If ecosystem simulation models are to be used to study changes in C distribution under proposed changes in climate, then they must represent the effects of soil physical conditions upon microbial activity. Hypotheses for the effects of soil water content () and temperature (T_s) on microbial oxidation rates were formulated into mathematical algorithms as part of the ecosys modelling program. Access to organic substrates by heterotrophic microbial populations was represented from competitive enzyme kinetics, which were presumed to be sensitive to . Access to O₂ by obligately aerobic or facultatively anaerobic microbial populations was represented from O₂ diffusion gradients and active uptake rates controlled by and T_s. Sensitivity to T_s of substrate hydrolysis and oxidation by heterotrophic microbial populations was modelled from an Arrhenius function. Rates of simulated respiration were tested against rates measured under laboratory and field conditions at different and T_s. Simulated CO₂ fluxes were largest when = 0.6 to 0.7 of total porosity and declined to <0.2 of their largest values when declined to 0.2 or rose above 0.9 of total porosity. The sensitivity of simulated CO₂ fluxes to was consistent with that measured during laboratory incubations, except in the range of 0.65 to 0.80 of total porosity, where sensitivity of measured fluxes was greater than that simulated. When was >0.8 of total porosity, simulated respiratory quotients rose above 1.0 to values consistent with those recorded elsewhere at high . Model hypotheses allowed simulated CO₂ evolution rates to reproduce those reported from wheat residue during a 30-d incubation at T_s from 0 to 20°C and _s from –0.033 to –5.0 MPa. These hypotheses also allowed simulated changes in CO₂ evolution rates attributed to changes in T_s and to reproduce those measured in the field during 60 d under barley.

K1A 0C6. CLBRR Contribution no. 94-57.

Received for publication September 7, 1993.

This article has been cited by other articles:

				R. F. Grant, M. Amrani, D. J. Heaney, R. Wright, and M. Zhang Mathematical Modeling of Phosphorus Losses from Land Application of Hog and Cattle Manure J. Environ. Qual., January 1, 2004; 33(1): 210 - 231. [Abstract] [Full Text] [PDF]

				R.F. Grant, N.G. Juma, J.A. Robertson, R.C. Izaurralde, and W.B. McGill Long-Term Changes in Soil Carbon under Different Fertilizer, Manure, and Rotation: Testing the Mathematical Model ecosys with Data from the Breton Plots Soil Sci. Soc. Am. J., January 1, 2001; 65(1): 205 - 214. [Abstract] [Full Text]