Fate and movement of selenium from drainage sediments disposed onto soil with and without vegetation

Disposal options for salty and selenium-laden agricultural drainage sediments are needed to protect the agricultural ecosystem in Central California. Thus, a 7-year pilot-scale field study evaluated the effects of disposing Se-laden drainage sediment onto soil that was planted with either salado grass (Sporobolus airoides 'salado') or cordgrass (Spartina patens 'Flageo'), or on soil left bare with and without irrigation. Significant decreases in salinity and water-extractable and total soil Se concentrations were observed in all treatments to a depth 30 cm, while water extractable Se and salinity increased most significantly between 30 and 60 cm. Total yields increased over time for both species, while plant Se concentrations were ≈10 and 12 mg kg−1 DM for salado and cordgrass, respectively. The results show that Se and soluble salts disposed of as Se-laden drainage sediment onto light textured soils will significantly migrate to lower depths with or without vegetation. -- Highlights: •Selenium-laden drainage sediment threatens the ecosystem in central California. •Depositing drainage sediment onto vegetated soils is a disposal option. •Phytomanagement of Se did not reduce the downward mobility of Se in the soil. •Disposal of Se-laden drainage sediment on vegetated light textured soils is not recommended. -- Phytomanagement was not effective in preventing the downward migration of selenium deposited as drainage sediment on light textured soil