MODELING THE EFFECTS OF INORGANIC AND ORGANIC AMENDMENTS ON ORGANIC-MATTER IN A QUEBEC SOIL

Simulation models can be used to predict the effects of soil managemen t, culture methods, and climate on soil organic matter levels. The obj ective of this study was to test the applicability of the CENTURY mode l to soils in southwestern Quebec and to examine the relative sensitiv ity of the model outcome to changes in various parameters. The model s imulated soil C and N within +/- 5% of the observed data over a 9-year period under continuous corn, Under high N fertilizer (40 g N m(-2)), both simulated and observed data indicated that soil C increased 20 t o 25%; model results indicated that the increase was mainly the result of increases in the slow C pool, For the input parameters analyzed, m odel results indicated that increased potential crop productivity and reduced harvest index would increase soil organic matter levels under continuous corn in eastern Canada.