CHARACTERISTICS OF SOME LOAMY-TEXTURED PODZOLS IN NORTHEASTERN ONTARIO

1982 ◽  
Vol 62 (2) ◽  
pp. 281-290 ◽  
Author(s):  
L. J. EVANS

Humo-Ferric Podzols (Typic Cryorthods) developed on glacial till or glaciolacustrine deposits were sampled in the Chapleau-Foleyet area of northeastern Ontario. pHs of Ae horizons ranged from 3.30 to 4.20 and of C horizons from 4.40 to 4.85. Cation exchange capacities (CEC) of mineral soil horizons averaged 1.7 meq/100 g, whilst those of the forest humus (fibrimors) averaged 166 meq/100 g. The CECs of the Bf and BC horizons were highly pH-dependent, averaging 3.2 meq/100 g at pH 4 and 16.8 meq/100 g at pH 8. The pH-dependency of CEC in these horizons was believed to be due to Al-complexes with organic matter. Calculated elemental loss using Zr as an internal standard showed significant losses of Mg, Fe, Ca and Al from Ae (albic) horizons and gains of Fe and, to a lesser extent, gains of Al in Bf (spodic) horizons. The clay mineralogy of Ae horizons was dominated by a high-charge smectite and that of Bf and BC horizons by chlorite.

1968 ◽  
Vol 48 (1) ◽  
pp. 53-63 ◽  
Author(s):  
J. S. Clark ◽  
W. E. Nichol

Heating in hydrogen peroxide, dilute oxalic acid, and dilute aluminum oxalate did not change the effective cation exchange capacity (CEC) or the pH-7 CEC of Wyoming bentonite and Alberni clay soil containing excess Al(OH)x. This indicated that treatment of soils with H2O2 to oxidize organic matter and the possible production of oxalates during oxidation did not change the CEC values of the inorganic fraction of soils even if some clay exchange sites were blocked by hydrous oxides of Al.With soils of pH less than approximately 5.4, oxidation of organic matter did not change the effective CECs although the pH-7 CEC values were decreased. Thus, organic matter in acid soils appeared to have little or no effective CEC. Because of this and the negligible effect of H2O2 oxidation on the CEC values of clays, the difference of the pH-7 CEC of soils before and after H2O2 oxidation provided a simple means of estimating the amount of organic pH-dependent CEC in acid soils.The amount of organically derived pH-dependent CEC was determined in a number of soils by means of peroxide oxidation. The technique provided a useful indication of the quantities of sesquioxide–organic matter complexes accumulated in medium- and fine-textured soils.


2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Hans Å. Persson

The spatial and temporal dynamics of tree fine roots were investigated in six boreal forests types in Eastern Sweden, close to the Swedish Forsmark and Laxemar nuclear power plants. Four dry and two wet forest types were included in the study. The amount of live and dead fine roots in terms of dry weight was estimated in soil cores. The live/dead ratios of fine roots (<1 mm in diameter) decreased with depth; very low ratios were observed in two wet forest sites. The proportions of dead fine roots to the total amounts of fine roots in the mineral soil horizons of those wet sites were 63 and 86%. The corresponding proportions in the mineral soil in dry forest sites were 45 and 45% and 49 and 48% at Forsmark and Laxemar, respectively. Sequential soil core sampling demonstrated a high variation in live and dead amounts of fine roots during the growth period. A high accumulation of carbon from dead tree fine root was found in all six forest types, in particular in the wet forest sites, but also in deeper soil horizons. Consequently, substantial amounts of organic matter from dead fine roots are continuously accumulated in the soil in boreal forests.


1994 ◽  
Vol 74 (4) ◽  
pp. 393-408 ◽  
Author(s):  
W. L. Meyer ◽  
P. A. Arp ◽  
M. Marsh

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


1964 ◽  
Vol 44 (2) ◽  
pp. 203-211 ◽  
Author(s):  
J. S. Clark

Low C.E.C. values were obtained for the B horizon of a Concretionary Brown soil from British Columbia and a Podzol from New Brunswick, when CaCl2 was used to saturate the cation-exchange complex. Higher CE.C.'s were obtained if Ca(OAc)2 + CaCl2 was used and this showed that the soils had a large pH-dependent component of the C.E.C. Both soils had a high proportion of pH-dependent charge after the destruction of the soil organic matter. Extraction of free iron oxides increased the C.E.C. of the inorganic exchange fractions and eliminated or decreased the pH-dependent component of the C.E.C. Relatively large amounts of iron and aluminum were removed from the soils by the free oxide extraction procedure. These results suggest that the fixation of aluminum and iron was responsible for the low permanent charge values obtained for the soils. The precipitation of the fixed Al and Fe as Al(OH)3 and Fe(OH)3 when the soils were treated with base or extracted with buffered salt solutions released exchange sites and gave an effect equivalent to the release of exchangeable H so that the soils had a large pH-dependent component of the C.E.C.


2006 ◽  
Vol 86 (1) ◽  
pp. 133-139 ◽  
Author(s):  
Edouard Lemire ◽  
Kate M Taillon ◽  
William H. Hendershot

Controlling soil pH is important to ensure good crop yield. This study was conducted to determine whether the accuracy of the existing Shoemaker-McLean-Pratt (SMP) pH-buffer method could be improved by using the pH-dependent cation exchange capacity curve (CECpd). Soil pH, SMP and CECpd measurements were performed on 18 acid surface horizon soil samples, with textures from sandy loam to clay loam. These soils were incubated with three levels of calcium carbonate for 12 wk, after which the soil pH and the effective cation exchange capacity (CECe) were measured. The correlation coefficient (R2) for the CECpd and CECe curves was 0.96. The main factor affecting the slope of the curves is the soil organic matter content. The increase of CECe in the soil was also found to be directly proportional to the amount of lime applied, regardless of the type of soil. By using the slope of the Qv versus pH curve for each soil and the relationship between CECe and lime application, we were able to determine the lime required to raise the soil pH in water to 6.5. As an alternative to the current practice of using the SMP buffer, we propose that it should be possible to estimate the pH-dependent CEC curve from measurable soil properties (e.g., organic matter) and to estimate the lime requirement as the difference in CECpd between the existing and desired pH values. Once the slope of the Qv/pH relationship has been determined or estimated for a soil, the only measurement necessary for calculating lime requirement in subsequent years would be the soil pH. The proposed method would provide lime requirement estimates while decreasing the annual cost of soil analysis. Key words: Lime requirement, cation exchange capacity, Non-Ideal Competitive Adsorption, soil properties, organic matter, Fe oxides


1967 ◽  
Vol 47 (3) ◽  
pp. 187-202 ◽  
Author(s):  
J. S. Clark ◽  
A. J. Green ◽  
W. E. Nichol

Studies of the cation exchange properties of the soils of Vancouver Island, British Columbia showed that, in general, the soils had high base saturation even though the precipitation was high. There was no consistent relation between the corrected lime potential values for the soils and the annual precipitation. The pH-dependent CEC values of the soils were highly correlated with organic matter and oxalate-extractable Al but poorer correlations were obtained with the clay content and oxalate-extractable Fe. The correlation between pH-dependent CEC and citrate-dithionite-extractable Fe was not significant. Complexes of Al with organic matter appeared to be the main source of the pH-dependent CEC in the soils.Soils from the drier southeastern part of the Island with fragipans had as low or lower corrected lime potential values in the upper part of the profile than did soils from the more humid and more densely forested parts of the Island. Although oxalate-extractable Al was accumulated in the upper solum of soils with fragipans there was no pronounced enrichment of either oxalate- or citrate-dithionite-extractable Fe. The corrected lime potential pattern and the free oxide distribution of the soils with fragipans differed from the soils without fragipans.


1971 ◽  
Vol 51 (1) ◽  
pp. 105-111 ◽  
Author(s):  
J. A. McKEAGUE ◽  
J. H. DAY ◽  
J. A. SHIELDS

Data for 16 measured and seven calculated properties of 461 samples from 115 soils occurring in various parts of Canada were coded, and a correlation analysis was run on the data for various groups of samples. In general, correlations of color value and organic matter were moderately high (|r| > 0.5) and significant, but for 21 Podzol Ae horizons the correlation was very low (r = −0.13) and not significant. Chroma and dithionite Fe were significantly correlated for several groups of samples but not for Podzolic B (spodic) horizons or Bm horizons. Linear regression equations expressing cation exchange capacity and pH-dependent charge as functions of organic matter and other variables fitted the data reasonably well. The danger of generalizing from presumed relationships among soil properties was indicated but, for some groups of samples, useful relationships existed between visible soil properties and properties measured in the laboratory.


Sign in / Sign up

Export Citation Format

Share Document