Managing high levels of boron and selenium with trace element accumulator crops

High concentrations of native extractable boron (B) and selenium (Se) found in some soil environments are detrimental to sustainable agriculture in many parts of the western U.S. As part of a strategy to reduce the impact of this problem, greenhouse and field experiments were conducted to study B and Se uptake in the following plant species used for bioremediation: Astragalus incanus L. (no common name), Creeping saltbush (Atriplex semibaccata R. Br. L.), Old Man saltbush (Atriplex nummularia Lindl. L.), Indian mustard (Brassica juncea Czern L.), tall fescue (Festuca arundinacea Schreb. L.), canola (Brassica napus L.), birdsfoot trefoil (Lotus corniculatus L.), and kenaf (Hibiscus cannabinus L.). In Experiment I, all five plant species, especially Indian mustard, accumulated and lowered soil Se concentrations more effectively when grown in selenate-treated soil than selenite-treated soil. In Experiment II, plant tissue concentrations of Se and B in Indian mustard increased proportionally to concentrations of Se and B in water culture. In Experiment III, Indian mustard, canola, and tall fescue accumulated and lowered native soil Se and B concentrations when grown under greenhouse conditions. In Experiment IV, Indian mustard accumulated the highest concentration of native soil Se and kenaf accumulated the highest concentration of native soil B under field conditions. Vegetation management with any of the above plant species should be considered as a bioremediation tool for removing boron or selenium from contaminated soils.