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

• Published in: Agronomy journal Vol. 105; no. 1; pp. 95 - 100
• Main Authors: Silveira, Maria L., Vendramini, Joao M. B., Sui, Xiaolin, Sollenberger, Lynn E., O’Connor, George A.
• Format: Journal Article
• Language: English
• Published: Madison The American Society of Agronomy, Inc 01.01.2013; American Society of Agronomy
• Subjects: Energy crops; Phytoremediation
• ISSN: 0002-1962; 1435-0645
• DOI: 10.2134/agronj2012.0307

Effective options for reducing P losses from P‐enriched soils remain a major challenge, particularly in intensive agricultural areas. While different strategies have been shown to control P mobility (e.g., Ca‐ and Al‐based soil amendments and riparian buffers), they provide no means to reduce in situ soil P concentrations. The objectives of this study were to: (i) investigate the potential P‐removal capacity of four bioenergy crops (elephantgrass [Pennisetum purpureum Schumach.], sugarcane [Saccharum spp.], switchgrass [Panicum virgatum L.], and stargrass [Cynodon nlemfuensis Vanderyst]) grown on a manure‐enriched soil, and (ii) examine the impacts of crop P uptake on soil P concentrations and surface groundwater quality. Treatments were distributed in a completely randomized design with four replicates. The greatest dry matter yields were observed for elephantgrass (average of 46 Mg ha−1 yr−1) followed by sugarcane (average of 40 Mg ha−1 yr−1). Tissue P concentrations were greater for stargrass (∼4 g kg−1) than elephantgrass (3.2 g kg−1) or sugarcane (1.9 g kg−1). Elephantgrass showed the greatest cumulative P removal (420 kg P ha−1 during the 3‐yr period). Soil P concentrations in the Ap horizon decreased with time, while an increase in soil P concentration was observed in the Bh horizon. Elephantgrass resulted in the lowest leachate P concentrations (∼0.5 mg P L−1) at the 60‐cm depth. Crop species had no effect on leachate P at the 90‐cm depth. Growth of elephantgrass as a biofuel feedstock appears to be an effective approach for remediation of excess soil P.