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Buffer capacity falls to 33% of the maximum value at pH = pK a ± 1, to 10% at pH = pK a ± 1.5 and to 1% at pH = pK a ± 2. For this reason the most useful range is approximately pK a ± 1. When choosing a buffer for use at a specific pH, it should have a pK a value as close as possible to that pH. [2]
The buffering capacity of a soil depends on the clay content of the soil, the type of clay, and the amount of organic matter present, and may be related to the soil cation exchange capacity. Soils with high clay content will have a higher buffering capacity than soils with little clay, and soils with high organic matter will have a higher ...
Acid-neutralizing capacity or ANC in short is a measure for the overall buffering capacity against acidification of a solution, e.g. surface water or soil water.. ANC is defined as the difference between cations of strong bases and anions of strong acids (see below), or dynamically as the amount of acid needed to change the pH value from the sample's value to a chosen different value. [1]
McIlvaine buffer is a buffer solution composed of citric acid and disodium hydrogen phosphate, also known as citrate-phosphate buffer. It was introduced in 1921 by the United States agronomist Theodore Clinton McIlvaine (1875–1959) from West Virginia University , and it can be prepared in pH 2.2 to 8 by mixing two stock solutions.
The degree to which a given amount of lime per unit of soil volume will increase soil pH depends on the buffer capacity of the soil (this is generally related to soil cation exchange capacity or CEC). Most acid soils are saturated with aluminum rather than hydrogen ions. Soil acidity generally results from hydrolysis of aluminum. [4]
Soil texture affects soil behaviour, in particular, its retention capacity for nutrients (e.g., cation exchange capacity) [8] and water. Sand and silt are the products of physical and chemical weathering of the parent rock ; [ 9 ] clay, on the other hand, is most often the product of the precipitation of the dissolved parent rock as a secondary ...
The addition of a small amount of lime, Ca(OH) 2, will displace hydronium ions from the soil colloids, causing the fixation of calcium to colloids and the evolution of CO 2 and water, with little permanent change in soil pH. The above are examples of the buffering of soil pH.
Soil acidification is the buildup of hydrogen cations, which reduces the soil pH. Chemically, this happens when a proton donor gets added to the soil. The donor can be an acid, such as nitric acid, sulfuric acid, or carbonic acid. It can also be a compound such as aluminium sulfate, which reacts in the soil to release protons.