Showing papers by "George A. O'Connor published in 2013"
TL;DR: In this paper, the authors identify potential crop species that can be used for remediation of soil P and as a cellulosic feedstock for production of renewable energy in South Florida.
Abstract: A recent alternative strategy to reduce environmental problems associated with P transport from agricultural soils is the use of bioenergy crops to remediate excess soil P. In addition to the positive impacts associated with P mitigation, harvested biomass used as a renewable energy source can also offset the cost associated with plant-based P remediation strategies. The objective of this study was to identify potential crop species that can be used for remediation of soil P and as a cellulosic feedstock for production of renewable energy in South Florida. Fifteen crop entries were investigated for their potential to remove P from a P-enriched soil. Dry matter (DM) yield varied among crop species with greatest yield observed for elephantgrass (Pennisetum purpureum Schum.) and sugarcane (Saccharum spp.) (43 and 39 Mg ha−1 year−1, respectively). Similarly, greater P removal rates were observed for elephantgrass (up to 126 kg P ha−1 year−1 in 2008) followed by sugarcane (62 kg P ha−1 year−1 in 2008). Although there was no effect (P = 0.45) of crop species on P reduction in the soil, soil P concentrations decreased linearly during the 3-year study. Because of its relatively greater DM yield and P removal rates, elephantgrass was shown to be a good candidate for remediation of excess soil P in South Florida Spodosols.
27 citations
TL;DR: Results were used to prioritize recommendations for future biosolids-borne TCC research, which include additional measurements of toxicological effects and TCC concentrations in environmental matrices at the field level.
27 citations
TL;DR: The use of living plants for in situ remediation of P-enriched soils is also known as phytoremediation and presents several major advantages over other P remediation techniques as discussed by the authors.
Abstract: 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
15 citations
TL;DR: In this article, the effects of temperature on the potential leachable P pool and distribution of chemical P forms in a biosolids-amended soil were evaluated, showing that increasing temperature (20 to 32°C) generally decreased cumulative P mass leached, suggesting greater soil affinity to retain P at 32°c than at 20°C.
Abstract: This study was designed to evaluate the effects of temperature on the potential leachable P pool and distribution of chemical P forms in a biosolids-amended soil. A P-deficient Spodosol was incubated with seven biosolids and inorganic P fertilizer at 20 and 32°C for 90 days. Amendments were applied to provide a total P concentration of 112 mg kg−1 soil, which correspond to a field application of ~224 kg P ha−1. Cumulative P mass leached during the 90 d study for any P source was <2% of the applied P, but greater cumulative P mass was released from the biological P removal and composted biosolids than from the heat-dried materials. Increasing temperature (20 to 32°C) generally decreased cumulative P mass leached, suggesting greater soil affinity to retain P at 32°C than at 20°C. In a static incubation experiment (no leaching), soil water-extractable P concentrations were reduced over time, but no temperature effect was observed. Similarly, P distribution among the various fractions was not affected by temperature. The relatively great ability of the soil to sorb P masked differences in biosolids properties and the potential impacts of temperature on P lability. Additional work using low P-sorbing soils is warranted.
7 citations
TL;DR: In this article, the feasibility of co-applying Gibberellins (GA) and reduced nitrogen (N) rates to produce a bioenergy crop less expensively was evaluated.
Abstract: Commercial fertilizer (particularly nitrogen) costs account for a substantial portion of the total production costs of cellulosic biomass and can be a major obstacle to biofuel production. In a series of greenhouse studies, we evaluated the feasibility of co-applying Gibberellins (GA) and reduced nitrogen (N) rates to produce a bioenergy crop less expensively. In a preliminary study, we determined the minimum combined application rates of GA and N required for efficient biomass (sweet sorghum, Sorghum bicolor) production. Co-application of 75 kg ha−1 (one-half of the recommended N rate for sorghum) and a modest GA rate of 3 g ha−1 optimized dry matter yield (DMY) and N and phosphorus (P) uptake efficiencies, resulting in a reduction of N and P leaching. Organic nutrient sources such as manures and biosolids can be substituted for commercial N fertilizers (and incidentally supply P) to further reduce the cost of nutrient supply for biomass production. Based on the results of the preliminary study, we condu...
2 citations
TL;DR: The root system of St. Augustinegrass was larger and deeper compared with zoysiagrass, promoting greater P uptake and less P leaching, and if tissue analysis indicates that P fertilization is required and the soil has the capacity to retain additional P, application of 0.8 g P m yr to zoysia and 1.07 g Pm yr to St Augustinegrass is appropriate and does not result in increased PLeaching.
Abstract: Phosphorus (P) is required to maintain healthy, high-quality, warm-season turf. However, excessive P applications to soils with poor P retention capabilities may lead to leaching losses to groundwater. This field study was conducted to determine the maximum P fertilizer application rate to (Walt.) [Kuntze] 'Floratam' St. Augustinegrass (St. Augustinegrass) and 'Empire' zoysiagrass (zoysiagrass) below which P leaching is minimized. Five P levels ranging from 0 to 5.0 g P m yr were surface applied as triple superphosphate. Turf was established on an uncoated, low-P sand with negligible P retention capacity. Leaf and root growth, tissue P concentration, soil P concentration, soil P saturation, leachate volume, and orthophosphate (P) concentration in leachates were measured. Mehlich 1-extractable soil P (M1-P) and soil P saturation ratio (PSR) increased with time as the P rate increased. Lower M1-P and PSR values were measured with St. Augustinegrass, which absorbed more P than did zoysiagrass. The root system of St. Augustinegrass was larger and deeper compared with zoysiagrass, promoting greater P uptake and less P leaching. If tissue analysis indicates that P fertilization is required and the soil has the capacity to retain additional P, application of 0.8 g P m yr to zoysiagrass and 1.07 g P m yr to St. Augustinegrass is appropriate and does not result in increased P leaching.
2 citations