Contribution of Organic Matter and Clay to Soil Cation‐Exchange Capacity as Affected by the pH of the Saturating Solution

Helling, Charles S.; Chesters, G.; Corey, R. B.

doi:10.2136/sssaj1964.03615995002800040020x

Cited by 298 publications

(128 citation statements)

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“…For example, organic matter content is sometimes estimated from the color value, and "free iron" from the hue and chroma. Equations have been derived to express the cation exchange capacity of certain soils as a function of clay and organic mattel (4). The total iron content of a soil cannot be predicted from color alone (L0), but soil color has been expressed as a function of iron and organic matter contents' pH and type of clay mineral (7).…”

Section: Introductionmentioning

confidence: 99%

Evaluating Relationships Among Soil Properties by Computer Analysis

McKeague¹,

Day²,

Shields³

1971

Can. J. Soil. Sci.

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Section: Introductionmentioning

confidence: 99%

Evaluating Relationships Among Soil Properties by Computer Analysis

McKeague¹,

Day²,

Shields³

1971

Can. J. Soil. Sci.

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“…Cation exchange reactions are vital to such key processes as nutrient leaching, fertilizer-soil interactions, nutrient supply to plants, and pH-buffering (Binkley and Richter 1987;Bouman et al 1995). Soil CEC is a complex characteristic because the measured value depends on several factors, the most important of which are texture, clay mineralogy, organic matter content, pH, and electrolyte concentration of the soil solution (Helling et al 1964;St. Arnaud and Sephton 1972;Rhoades 1982;Curtin et al 1984).…”

mentioning

confidence: 99%

“…Although several workers have succeeded in predicting CEC at a specific pH (Helling et al 1964;St. Arnaud and Sephton 1972), a function that accounts for the pH-dependence of CEC is lacking.…”

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confidence: 99%

Cation exchange and buffer potential of Saskatchewan soils estimated from texture, organic matter and pH

Curtin¹,

Rostad²

1997

Can. J. Soil. Sci.

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. W. 1997. Cation exchange and buffer potential of Saskatchewan soils estimated from texture, organic matter and pH. Can. J. Soil Sci. 77: 621-626. Cation exchange capacity (CEC) data provide information on important chemical attributes of soil (e.g., ability of soil to retain cations against leaching and to buffer pH). Measurements of CEC are expensive to perform. Further, since CEC is dependent on measurement pH, CEC data are difficult to interpret, especially in the case of soils whose field pH is far removed from measurement pH. We analyzed a large data set (n = 1622), collected in support of soil survey activities in Saskatchewan, to develop a method of estimating CEC as a function of pH and to establish relationships between soil buffer capacity and properties such as texture and organic matter content. A regression equation with organic C and clay as independent variables explained 86% of the variability in CEC measured using BaCl 2 buffered at pH 8.2. The CECs (at pH 8.2) of organic matter and clay were estimated at 2130 and 510 mmol (+) kg -1 , respectively. About 15% of exchange sites were not accounted for by organic matter and clay and were assumed to reside in the fine silt fraction. The CEC at field pH, i.e., effective CEC (ECEC), was described (R 2 = 0.86 *** ) by a function based on the assumption that the ECECs of organic matter and clay increase linearly as pH increases to 8.2, where their values are 2130 and 510 mmol (+) kg -1 , respectively. This relationship is especially useful because it enables soil CEC to be estimated at any pH based solely on organic matter and texture. Soil buffer capacity values were obtained by estimating the change in soil ECEC (or titratable acidity) needed to produce a unit change in pH. Buffer strength of clay was low [~30-50 mmol (±) kg -1 (pH unit) -1 ]. Our estimates of organic matter buffer capacity [~400 mmol (±) kg -1 (pH unit) -1 ] were consistent with published values. The results suggest that prairie soils that are low in organic matter may be susceptible to acidification even if clay content is relatively high. Elles sont malheureusement onéreuses à obtenir. En outre, vue la dépendance de la CEC envers le pH mesuré, ces valeurs sont difficiles à interpréter, en particulier lorsque le pH réel sur le terrain est très éloigné du pH mesuré en laboratoire. Nous avons analysé un grand nombre de jeux de données (n = 1 622) recueillies dans le cadre d'études pédologiques en Saskatchewan, afin de mettre au point une méthode d'estimation de la CEC en fonction du pH et d'établir les rapports existant entre le pouvoir tampon du sol et des propriétés comme la texture et la teneur en matière organique. Une équation de régression utilisant les teneurs en C organique et en argile comme variables indépendantes permettait de justifier 86 % de la variabilité de la CEC mesurée dans BaCl 2 tamponnée à pH 8,2. Les valeurs CEC, à pH 8,2, de la matière organique et de l'argile étaient évaluées, respectivement, à 2 130 et à 510 mmol (+) kg -1 . Près de 15 % des sites d'échange ...

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“…He stated that a divalent displacing cation gives higher values than a monovalent cation and even cations of the same valency give different results. HELLING et al ( 9) showed that the CEC value of soil organic matter is highly pH-dependent and increases faster than that of clay between pH 2.5 and 8.0.…”

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confidence: 99%