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Title: Influence of soil solution cation composition on boron adsorption by soils

Author
item Goldberg, Sabine
item Suarez, Donald

Submitted to: Soil Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/26/2010
Publication Date: 2/1/2011
Citation: Goldberg, S.R., Suarez, D.L. 2011. Influence of soil solution cation composition on boron adsorption by soils. Soil Science. 176(2):80-83.

Interpretive Summary: Boron is a specifically adsorbing anion that can be detrimental to plants at elevated levels. Detrimental levels can occur because of high levels of boron in the soil solution or from additions of boron via the irrigation water. Adsorption of boron by five soil samples was evaluated as a function of solution pH and major cation composition. Boron adsorption was independent of major cation composition in the agriculturally important pH range of 4 to 8. Our results will benefit scientists who are developing models of boron movement in arid zone soils. The results can be used to improve predictions of boron behavior in soils and thus aid action and regulatory agencies in the management of soils and waters which contain elevated concentrations of boron.

Technical Abstract: Boron (B) adsorption on five arid-zone soil samples from California was investigated as a function of solution pH (4-10) and cation composition (Na, Ca, or Mg). Boron adsorption increased with increasing solution pH, reached an adsorption maximum near pH 9, and decreased with further increases with pH. Boron adsorption as a function of solution pH was independent of solution cation composition from pH 4 to 8. Above pH 8 increased B loss from solution was found for the magnesium systems. Chemical speciation calculations indicated supersaturation with respect to the Mg-silicate minerals, chrysotile and sepiolite above pH 7.8 suggesting that B is removed from solution by either adsorbing to or coprecipitating with these minerals. For the purposes of describing B transport under agricultural conditions (pH 4-8) it is advantageous that B adsorption can be described without consideration of changes in solution cation composition.