| This study was conducted on two toposequences located adjacent to the Breton Plots. The objectives were to quantify: (1) the distribution of soil types, soil organic matter and macro-organic matter, and the seasonal variation of soil water and temperature, available nutrients, crop production, and microbial biomass along toposequences; and (2) the dynamics of soil C, N and P under laboratory conditions. Field and laboratory studies showed that the quantity of soil organic matter, microbial biomass, and C and N mineralization increased from upper to lower slope positions in both fields, however the specific soil mineralization rates of C, N and 15N, and the proportion of microbial biomass to total organic matter decreased from upper to lower slope positions. Therefore, factors controlling microbial activity (quantity of organic matter, moisture content, temperature, and nutrient availability) at different slope positions need to be considered in assessing organic matter dynamics in soils along toposequences. |
