Effects of supplementary nutrients (soil-nitrogen or foliar-iron) on switchgrass (Panicum virgatum L.) grown in Pb-contaminated soil
Abstract
Lead (Pb) soil contamination is widespread and poses a threat to human health. Even long-term exposure to low levels of Pb contaminated soils is potentially harmful to organisms. Soil remediation options include phytoextraction that has gained particular attention due to low cost and minimal soil disruption. The North American native switchgrass (Panicum virgatum L.), a second-generation bioenergy crop was used in this study due to its ability to produce high biomass and grow on marginal lands. In this study, the effects of supplementary soil nitrogen (N) or foliar iron (Fe) application on the growth and metal uptake of switchgrass were examined. Plants were grown under controlled conditions using Pb (5802.5 mg kg−1) contaminated soil. The soil nitrogen (N) application involved three levels: control (no added N), medium (500 mg kg−1), and high (1000 mg kg−1). Plants receiving the high N had the significantly greatest dry mass (DM) of the foliage and the highest Pb concentration. The iron (Fe) foliar application involved two levels: (1) deionized water and (2) iron (20 mg kg−1) solution. Plants were additionally treated with the soil fungicide propiconazole (2 mg L−1) and the soil chelate nitrilotriacetic acid (NTA) in order to enhance phytoextraction. Plants receiving the Fe foliar application had significantly higher DM of the foliage and significantly lower Pb concentrations in the roots and the foliage. These results will potentially improve phytoextraction by switchgrass grown in Pb contaminated soils.