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Title: Adsorption and desorption of B in column studies as related to PH: Results and model predictions

Author
item Suarez, Donald
item Wood, James
item Taber, Jr, Patrick

Submitted to: Vadose Zone Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/12/2012
Publication Date: 5/1/2012
Citation: Suarez, D.L., Wood, J.D., Taber, Jr, P.E. 2012. Adsorption and desorption of B in column studies as related to PH: Results and model predictions. Vadose Zone Journal. 11:DOI:10.2136/vzj2011.0073.

Interpretive Summary: Impaired waters, especially irrigation drainage waters and treated municipal waste waters, often contain elevated B concentrations. Elevated B concentrations pose a potential risk to crop production and may restrict use of these waters for irrigation, thus there is a need to develop capability to predict B concentrations and transport in soils. We evaluated the capability of using a generally available soil properties to predict the parameters of a B adsorption model and coupled the model to the UNSATCHEM transport model. The model provided adequate fit to the experimental data and highlighted the very strong dependence of B mobility on soil pH. Results will enable users to better evaluate the impact of high B irrigation water on soil boron concentrations and to develop management practices for the use of these waters for irrigation.

Technical Abstract: Boron is an element with a narrow range between deficiency and toxicity for plants. Reuse of agricultural drainage waters and treated municipal wastewaters is impaired by the often elevated concentrations of B. Knowledge of the B concentrations in soil solution and transport of B out of the soil, is essential for management of waste waters. Prediction of B concentrations requires consideration of B adsorption and desorption, which are dependent on soil properties and solution composition, especially pH. We first applied a 0.08 mmol B solution to three arid land soils from S California and subsequently leached the soils with a low B solution. The experiment was conducted at pH 6.8 and 8.6. The experimental data compared well with predictions using the UNSATCHEM transport model with the constant capacitance model and prediction of the model constants based on soil properties, without the need for soil specific determinations of B adsorption characteristics. Use of a single generalized set of constants for all soils did provided an equally satisfactory fit to the experimental data