Use of Warm-Season Grasses Managed as Bioenergy Crops for Phytoremediation of Excess Soil Phosphorus

Published in Agron. J. 105:95–100 (2013) doi:10.2134/agronj2012.0307 Copyright © 2013 by the American Society of Agronomy, 5585 Guilford Road, Madison, WI 53711. All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. P management in agricultural systems continues to be a relevant issue of agronomic and environmental importance. Decades of excessive manure or fertilizer applications in intensive agricultural systems have resulted in signifi cant soil P accumulation at levels exceeding plant uptake (Sharpley et al., 1994). Excess soil P in agricultural lands can subsequently be transported to aquatic systems, contributing to eutrophication of surface waters (Sharpley et al., 1994; Daniel et al., 1998; Haygarth and Jarvis, 1999). Th us, there has been a growing interest in developing strategies that reduce soil P lability and the potential environmental risks associated with off -site transport of P. Current approaches to reduce P losses from agricultural areas include the utilization of soil chemical amendments and agricultural best management practices. Chemical amendments such as alum, ferric chloride, and lime have been used to reduce the availability of water-soluble P in manureimpacted soils (Moore and Miller, 1994; Dao, 1999; Dou et al., 2003). Numerous studies have investigated the eff ectiveness of Al-based water treatment residuals as a potential soil amendment to control P solubility in P-impacted soils in both the short and long term (Silveira et al., 2006; Agyin-Birikorang and O’Connor, 2007; Oladeji et al., 2007). Although chemical amendments have been shown to eff ectively reduce off -site movement of P into surface water bodies, they generally fail to prevent P accumulation or reduce total P concentrations in the soil. Th us, the threat of P solubilization and subsequent transport to surface waters remains aft er the application of soil amendments. Moreover, P immobilization by chemical amendments does not prevent P losses via soil erosion. Th erefore, alternative approaches to remediate in situ soil P levels are critical to address environmental concerns related to water quality issues. An alternative to reduce the environmental risks associated with P transport from agricultural lands is the direct use of living plants for in situ remediation of P-enriched soils (Delorme et al., 2000; Gaston et al., 2003). Th is approach, also known as phytoremediation, presents several major advantages over other P remediation techniques. Unlike chemical approaches that only control the solubility of P in the soil, P taken up in plant tissue can be removed from the site when the plants are harvested. Phosphorus accumulation in plant tissue can reduce soil P concentrations and prevent P losses to the environment. Because of their relatively high dry matter yields and P-removal potential, there has been a growing interest in the use of forages for the uptake of nutrients from land-applied animal manure (Schmitt et al., 1999; Cherney et al., 2002; Woodard et al., 2002; Newton et al., 2003; Mikhailova et al., 2003; Rowe and Fairbrother, 2003; Johnson et al., 2004). In addition to the positive impacts associated with P mitigation, ABSTRACT