| Autor: |
Donald, Richard G., Anderson, Darwin W., Stewart, John W. B. |
| Zdroj: |
Soil Science Society of America Journal; November 1993, Vol. 57 Issue: 6 p1611-1618, 8p |
| Abstrakt: |
Soils of the northern boreal forest have undergone significant pedogenic losses of P. This study was undertaken to examine the hypothesis that the leaching of dissolved organic carbon (DOC) is a mechanism for P removal from forested soils. The sorption of DOC and DOC fractions by soil horizons from the shoulder, backslope, and footslope soils of a catenary sequence was examined. Variation in DOC sorption among the soil horizons, and between positions in the catena, was related to differences in the clay content (r= 0.71) and citrate‐dithionate‐extractable Fe, Al, and Mn (r= 0.66). The hydrophobic acid and the hydrophilic acid fractions were the most abundant in the soil solution (72% of the total DOC) and accounted for most of the sorption of DOC in the Bt and C horizons (isotherm distribution coefficient Kd= 27.1 × 10−4to 337 × 10−4m3kg−1). The hydrophobic neutral fraction (14% of the DOC) was not sorbed by any of the soil horizons (average Kd= 20.0 × 10−4m3kg−1). The hydrophobic neutral fraction (14% of the DOC) was not sorbed by any of the soil horizons (average Kd= 20.0 × 10−4m3kg−1). The hydrophobic neutral fraction had a molar C/P ratio of 2800, compared with 21 000 and 35 600 for the hydrophobic acid and hydrophilic acid fractions, respectively. Phosphorus in the hydrophobic neutral fraction constituted 64% of the P measured in these three fractions. The high P content and low sorption of the hydrophobic neutral fraction suggests that the leaching of the hydrophobic neutral fraction may be a possible mechanism for the redistribution and loss of P in these soils. |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
|
Plný text