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1 , USDA-ARS, Water Management Research Unit, 9611 S. Riverbend Ave., Parlier, CA 93648, USA (e-mail: gbanuelos{at}fresno.ars.usda.gov)
2 Department of Biological Sciences and Environmental Sciences Program, Southern Illinois University Edwardsville, Edwardsville, IL 62026-1650, USA
Agricultural drainage waters in the western San Joaquin Valley of Central California contained high levels of salts, boron (B) and selenium (Se). Discharge of the drainage directly into the Kesterson Reservoir was hazardous to plants and wildlife. To investigate the plausibility of using plants as recipients for disposing of poor-quality drainage-waters, multi-year field studies were conducted to reuse drainage water on plants that are salt and B tolerant, and accumulate or stabilize soluble Se from the drainage. Installation of a subsurface tile drainage system in cropping fields allowed drainage waters to be collected and subsequently reused on tolerant plants. The tested plant species included Lactuca sativa, Lycopersicon esculentum, Gossypium hirsutum L., Medicago sativa L., Brassica napus var. Hyola, Helianthus annuus, Distichlis spicata L., and Salicornia bigelovii Torr. The quality of drainage water decreased along the water reuse path, with a sulphate-dominated salinity change from 4.5 to 15.2 dS m-1; soluble B from 3.4 to 14.5 mg L-1; and soluble Se from 0.08 to 1.18 mg L-1. Soil salinity and concentrations of B and Se increased with decreasing quality of reused drainage waters. This study demonstrated the importance of monitoring changes in soil quality for sustaining such a plant-based system.
