About Us | Help Videos | Contact Us | Subscriptions



This article in SSSAJ

  1. Vol. 61 No. 4, p. 1159-1175
    Received: June 25, 1996

    * Corresponding author(s): rgrant@gpu.stv.ualberta.ca
Request Permissions


Changes in Soil Organic Matter under Different Tillage and Rotation: Mathematical Modeling in ecosys

  1. R. F. Grant 
  1. Department of Renewable Resources, University of Alberta, Edmonton, Alberta, Canada T6G 2E3



Reductions in both tillage and fallowing may increase soil organic C. The effects of tillage and fallowing on soil C could be estimated under site- and climate-specific conditions by mathematical modeling. The simulation model ecosys predicts changes in soil C by calculating C added through fixation by plant communities and C lost through oxidation by microbial communities. During a 14-yr simulation of a field experiment in a semiarid environment, ecosys predicted that 18 and 20 g m−2 yr−1 more C would be sequestered in the upper 0.15 m of soil in continuous wheat (W-W; triticum aestivum L.) than in wheat-fallow (W-F) under conventional tillage (CT) and no tillage (NT), respectively. During the same period, ecosys predicted that 14 and 12 g m−2 yr−1 more C would be sequestered in the upper 0.15 m of soil under NT than under CT in W-W and W-F, respectively. These increases were compared with those measured from the field experiment of 9 and 19 g m−2 yr−1 in W-W than W-F under CT and NT, respectively, and of 13 and 4.5 g m−2 yr−1 under NT than CT in W-W and W-F, respectively. The sensitivity of simulated changes in soil C to doubled atmospheric CO2 and a 3 or 6°C increase in air temperature was then tested. Similarity in the direction and magnitude of simulated and measured changes in soil C lend initial support to model hypotheses. However, there are some issues concerning the modeling and measurement of soil C that require further clarification.

  Please view the pdf by using the Full Text (PDF) link under 'View' to the left.

Copyright © . Soil Science Society of America