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Cation-exchange capacity (CEC) is a measure of how many cations can be retained on soil particle surfaces. [1] Negative charges on the surfaces of soil particles bind positively-charged atoms or molecules (cations), but allow these to exchange with other positively charged particles in the surrounding soil water. [ 2 ]
Laboratory tests used to diagnose a soil as dispersive focus on the cation exchange capacity of a soil sample and its cation breakdown. Soil cations are dominated by Ca 2+, Mg 2+, K +, and Na +, as well as H + in acidic soils. The exchangeable sodium percentage ( "ESP", (sodium / (total cations)) * 100 ) is a key indicator derived from these ...
The WRB defines five Reference soil Groups with a compulsory argic horizon. Only the Retisols have retic properties. The other four are differentiated according to the cation exchange capacity per kg clay at pH 7 (CEC / kg clay) in the argic horizon and according to the base saturation calculated per sum of exchangeable cations (BSeff) in the ...
CEC is the amount of exchangeable hydrogen cations (H +) that will combine with 100 grams dry weight of soil and whose measure is one milliequivalent per 100 grams of soil (1 meq/100 g). Hydrogen ions have a single charge and one-thousandth of a gram of hydrogen ions per 100 grams dry soil gives a measure of one milliequivalent of hydrogen ion.
LX Lixisol (low-activity clays, exchangeable base cations ≥ exchangeable Al) AL Alisol (high-activity clays, exchangeable Al > exchangeable base cations) LV Luvisol (high-activity clays, exchangeable base cations ≥ exchangeable Al) Note: The exchangeable base cations are given in cmol c kg −1. Soils with little or no profile differentiation
Base-cation saturation ratio (BCSR) is a method of interpreting soil test results that is widely used in sustainable agriculture, supported by the National Sustainable Agriculture Information Service (ATTRA) [1] and claimed to be successfully in use on over a million acres (4,000 km 2) of farmland worldwide.
The sodium adsorption ratio (SAR) is an irrigation water quality parameter used in the management of sodium-affected soils.It is an indicator of the suitability of water for use in agricultural irrigation, as determined from the concentrations of the main alkaline and earth alkaline cations present in the water.
The relative ability of soils to store one particular group of nutrients, the cations. The most common soil cations are calcium, magnesium, potassium, ammonium, hydrogen, and sodium. The total number of cations a soil can hold, its total negative charge, is the soil's cation exchange capacity.