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

Abstract

. 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 ...

Particle size distribution fitting of surface detrital sediment using the Swrebec function

“…For geosciences, many sediment characteristics are correlated with particle size properties, such as (1) hydraulic including porosity, permeability, bulk density and residual water content (Boadu 2000); (2) electrical including chargeability, surface conductivity and dielectric spectroscopy (Cronican and Gribb 2004); (3) transport such as tortuosity, dispersivity or intrinsic permeability (Indraratna et al 2012); (4) reactive properties such as cationic exchange capacity, specific surface and reaction kinetics (Curtin and Rostad 1997), (5) chemical composition (Weltje and von Eynatten 2004;Sierra et al 2011); (6) the presence of some natural isotopes such as 40 K, 238 U, and 232 Th (Frindik and Vollmer, 1999); and (7) the origin, transport conditions and depositional environment of sediments (McLaren and Bowles 1985;Flemming 2007).…”

Soil properties controlling Zn speciation and fractionation in contaminated soils

“…As an estimate for the concentration of available sorption sites, we calculated the potential cation exchange capacity of each soil from its soil organic carbon and clay content according to a relation derived from the analysis of 1600 Canadian soils (Curtin and Rostad, 1997): PCEC (in mmol c /kg) = 3.97 Â f oc + 0.57 Â f cl , where 3.97 and 0.57 are the concentrations of sorption sites on organic carbon and clay (in mmol c /kg at pH 8.2) and f oc and f cl are the mass fractions of soil organic carbon and clay, respectively. As a measure for Zn loading relative to available sorption sites, the ratio of total Zn content (in charge equivalents) divided by the PCEC (Zn eq /PCEC) was calculated for each soil.…”

Effect of Topography and Soil Depth on Clay Content, Organic Matter Content, Active Acidity, Reserve Acidity and Cation Exchange Capacity of Some Tea Soils of Bangladesh

“…The proper growth of plants, like tea, jute, coffee etc. mainly depends on soil management, physicochemical properties and nutrient status of soil and their availability to plants [1][2][3][4][5][6][7][8]. However, the reproductivity as well as survival of microorganisms depends largely on active acidity, reserve acidity, buffer capacity and cation exchange capacity (CEC) of the soil [9][10][11][12][13][14].…”