Selenium Mobility in Irrigated Soil Columns as Affected by Organic Carbon Amendment
- Rosemary H. Neal * and
- Garrison Sposito
Samples of two agricultural soil profiles were collected from the western San Joaquin Valley, CA, and packed into 1.5-m columns. The soils were leached sporadically over 9 wk with an aqueous solution containing selenate and subjected to two different chemical environments in order to investigate the effects of an added C source and intermittent irrigation on the fate of applied Se. Evaluation of the soluble Se present in the soil columns at the end of the leaching experiments showed the movement of Se to be retarded with respect to that of the leaching solution, and this was attributed to the effect of intermittent irrigation on the behavior of Se in the soil columns. Under control conditions, soluble Se was predominantly in the selenate form, whereas the inclusion of a C amendment resulted in reduced total soluble Se in the upper portions of the columns and transformation to organically associated Se. Elevated concentrations of soluble Mn were found where selenate had transformed to selenite and organically associated Se, indicating the possibility of localized reduction processes.
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