Cation exchange capacities of upland soils in eastern Canada

Abstract

Relationships between cation exchange capacity (CEC), clay and organic carbon contents and soil pH were analyzed by way of multiple regressions for upland soils in eastern Canada (mostly Ontario, with additional data for New Brunswick). This was done by vegetation type in an attempt to explain some of the otherwise unexplained CEC variations. Data were taken from about 2000 soil horizons (organic L, F, and H horizons as well as A, B, and C mineral soil horizons) under broadleaves (mostly maples, beech, birch or aspen as dominant species), conifers (mostly fir, spruces and/or pines), and grass vegetation. For the organic forest floor horizons (or L, F, and H horizons), both organic carbon content (%) and pH were highly significant for predicting CEC, i.e.,CEC (L, F, and H of broadleaves) = −38 + 0.71 × org. C (%) + 10.3 × pH (R2 = 0.69), andCEC (L, F and H of conifers) = −31 + 0.34 × org. C (%) + 12.1 × pH (R2 = 0.58).For the mineral soil, clay and organic carbon contents (%) and pH were highly significant for predicting CEC. Soils with forest vegetation were found to have lower contributions of organic matter to CEC than grassland soils, i.e.,CEC (forest soils) = −7.0 + 0.29 × clay (%) + 0.82 × org. C (%) + 1.4 × pH (R2 = 0.72),CEC (wooded grasslands) = −6.0 + 0.31 × clay (%) + 1.31 × org. C (%) + 1.0 pH (R2 = 0.74), andCEC (grasslands) = −8.3 + 0.24 × clay (%) + 2.14 × org. C (%) + 1.3 × pH (R2 = 0.79).Relationships that were developed from Ontario data for specific vegetational types (maple sites, strongly podzolized conifer sites, grasslands/croplands) were tested by comparing CEC predictions with reported values for similar sites in New Brunswick and Quebec. The predictions were consistent with the general trends for maple sites and grasslands/croplands, but CEC values were strongly overpredicted for Podzolic subsoils on conifer sites.Literature information of the CEC dependency on in situ pH is sparse. Existing information that is based on buffering grassland/cropland soil samples from pH 2.5 to 8 appears to mimic this dependency quite well. Key words: Cation exchange capacity, clay, organic carbon, soil pH, forests, grasslands

Development of ensemble pedotransfer functions for cation exchange capacity of soils ofQingdao inChina

“…() produced the smallest overall error, and PTF of Meyer et al . () the largest. It is interesting to note that for the bias‐removed CEC predictions, the RMSE and EC values tended to be higher and lower for PTFs with larger systematic error, respectively.…”

“…For example, the PTFs of Foth & Ellis () and Meyer et al . (), which were found to produce the larger bias than other PTFs, had the highest RMSE and the lowest EC for the bias‐removed predictions. This demonstrated significant influence of the bias on the CEC predictions.…”

“…It is interesting to note that for the bias-removed CEC predictions, the RMSE and EC values tended to be higher and lower for PTFs with larger systematic error, respectively. For example, the PTFs of Foth & Ellis (1997) and Meyer et al (1994), which were found to produce the larger bias than other PTFs, had the highest RMSE and the lowest EC for the bias-removed predictions. This demonstrated significant influence of the bias on the CEC predictions.…”

A Simple Geospatial Nutrient Budget Model for Assessing Forest Harvest Sustainability across Nova Scotia, Canada

“…Trends in CEC were, however, poorly correlated with changes in % Clay and % OM. This could, in part, be due to small sample size and appreciable scatter between field-determined and modelled CEC values (Meyer et al, 1994).…”

Modelling and mapping critical loads and exceedances for the Georgia Basin, British Columbia, using a zero base-cation depletion criterion

“…Wet deposition was interpolated from all available precipitation chemistry observations (NatChem); modelled total deposition for the period 2005-2006 was obtained from the CMAQ model. Missing data for CEC were in part generated following Meyer et al (1994), using specified values for clay and OM content, and soil pH(H 2 O).…”