A New Method for the Simultaneous Measurement of pH-Dependent Cation Exchange Capacity and pH Buffering Capacity

2004 ◽  
Vol 68 (5) ◽  
pp. 1578-1585 ◽  
Author(s):  
K. Oorts ◽  
B. Vanlauwe ◽  
J. Pleysier ◽  
R. Merckx
1977 ◽  
Vol 57 (3) ◽  
pp. 233-247 ◽  
Author(s):  
ROGER W. BARIL ◽  
THI SEN TRAN

Correlations were made among chemical criteria used for taxonomic soil classificaton. The compared tests were: oxalate Δ (Fe + Al), pyrophosphate-extractable (Fe + Al), oxalate-extractable Al, pH-dependent cation exchange capacity (ΔCEC), ratios of pyrophosphate-extractable (Fe + Al) over clay or over dithionite-extractable (Fe + Al), and finally soil pH measured in 1 M NaF. Significant correlations were found among various measured parameters. However, no single test was found to be reliable as a single criterion when applied to the taxonomic classification of Quebec soils. The two chemical tests, pyrophosphate-extractable (Fe + Al) and its ratio over clay, combined with morphologic criteria appeared useful for classifying Quebec Podzols. A few soils, which presented discrepancies from chemical criteria were found difficult to classify, thus suggesting the possibility of establishing new sub-groups in the Canadain soil taxonomic classification system.


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.


Soil Science ◽  
1970 ◽  
Vol 109 (5) ◽  
pp. 272-278 ◽  
Author(s):  
B. L. SAWHNEY ◽  
C. R. FRINK ◽  
D. E. HILL

HortScience ◽  
2007 ◽  
Vol 42 (2) ◽  
pp. 349-352 ◽  
Author(s):  
Janet F.M. Rippy ◽  
Paul V. Nelson

Variations in moss peat cation exchange capacity (CEC) and base saturation (BS) can result in inconsistent initial pH in moss peat-based substrates created using standard formulas for limestone additions and can lead to subsequent drift from the initial pH in those substrates. This study was conducted to determine the extent of such variation. CEC and BS were measured in three replications on 64 moss peat samples that were selected from three mires across Alberta, Canada, to represent maximum gradients in plant species composition within six degrees of decomposition acceptable for professional peat-based substrates. CEC ranged from 108 to 162 cmol·kg−1 (meq·100 g). Averaged overall samples, BS ranged from 15% to 71% of CEC and calcium accounted for 68%, magnesium for 25%, sodium for 5%, and potassium for 1.4% of BS. CEC was positively correlated to the amount of Sphagnum fuscum (Schimp.) Klingrr. in the sample (r = 0.22). BS was positively correlated to the amount of sedge (r = 0.28). Neither CEC nor BS was influenced by degree of decomposition (r = 0.002 and r = 0.08, respectively). Moss peats with high CEC have a greater buffering capacity than those with low CEC, resulting in less pH drift. Moss peats with high BS should have a low neutralization requirement to achieve a target pH. Understanding the species composition in peat-based substrates can alleviate problems of inconsistent initial pH and subsequent pH drift.


2011 ◽  
Vol 6 (3) ◽  
Author(s):  
J. Zake ◽  
J. Y. Z. Kitungulu ◽  
H. Busurwa ◽  
F. Kyewaze

Wetlands are not wastelands but wealth lands, which are widely distributed throughout Uganda currently covering 11% of the total land area. They are accessible to a large proportion of the population. As the country's population grows, people increasingly convert wetlands for other land uses such as farming, settlement among others thus making it difficult to enforce legislation for their protection, sustainable management and utilization. Their profound importance to both humans and wildlife calls for a concerted effort to ensure their sustainable utilization and attempts should be made to promote sustainable development of such wetlands with adequate considerations being given to human and environmental requirements. This study was therefore carried out to determine the effect of drainage on organic matter levels and on soil chemical changes in wetland soils in eastern Uganda around the Lake Victoria basin. Secondly, to assess potential lime requirements for drained wetland soils in eastern Uganda around the Lake Victoria basin, this would reflect on wetland soil buffering capacity. In green house studies it was found that drainage of wetland soils led to a reduction of organic matter relative to soil structure and where sulfur and iron were present in large amounts, drainage caused decrease in soil pH to moderately acidic levels; but in cases where exchangeable bases were present in large amounts there was an increase in soil pH. Lime requirements were greater where the amount of clay, organic matter and cation exchange capacity were high. Consequently, such wetland soils had a high buffering capacity. It was concluded that wetland soils should be characterized in terms of potential of acidification, level of organic matter, nutrient content, cation exchange capacity, soil texture and levels of trace elements. Decisions to drain or not to drain should depend on these parameters and other socio-economic considerations for the area.


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