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Eric D. Roy
Dep. of Civil and Environmental Engineering, Gund Institute for Environment, and Rubenstein School of Environment and Natural Resources Univ. of Vermont Burlington VT 05405 USA

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Special section
Published: 15 July 2021 in Journal of Environmental Quality
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Dissolved air flotation (DAF) has shown potential to substantially improve phosphorus (P) mass balance on dairy farms by capturing P associated with fine solids from liquid manure enabling new management options. However, at <25% total solids, further dewatering is necessary to facilitate export of recovered fine solids off farm for use in bagged or bulk products. Physical conditioners such as quicklime (QL) and lime kiln dust (LKD) are commonly used to enhance mechanical dewatering of biosolids, but their effect on the properties and fertilization value of DAF-captured manure fine solids has not been documented. We generated plant foods using DAF-captured dairy manure fine solids conditioned with 3, 4.5, and 6% m/m QL or LKD and dewatered using a benchtop press for comparison with thermally dried fine solids. Tomato seedlings were grown in a soilless substrate amended with 6% v/v plant food, as well as an unamended control. Thermally dried and LKD plant foods produced significantly greater seedling biomass than QL plant foods and the unamended control. QL and LKD conditioned fine solids contained approximately 30x and 10x less water-extractable P than thermally dried fine solids, respectively—likely due to precipitation of Ca-P minerals. Elevated pH (≥10) of the lime-conditioned fine solids could have also suppressed plant growth. These effects limit horticultural applications, but could be beneficial in agricultural field settings where slow-release P is desirable. Research beyond this preliminary assessment is needed to determine the practicality and sustainability of the approach, along with longer-term nutrient bioavailability. This article is protected by copyright. All rights reserved

ACS Style

Katherine K. Porterfield; Doug VanOrnum; Eric D. Roy. Assessment of lime‐conditioned dairy manure fine solids captured using dissolved air flotation for fertilization in horticulture. Journal of Environmental Quality 2021, 1 .

AMA Style

Katherine K. Porterfield, Doug VanOrnum, Eric D. Roy. Assessment of lime‐conditioned dairy manure fine solids captured using dissolved air flotation for fertilization in horticulture. Journal of Environmental Quality. 2021; ():1.

Chicago/Turabian Style

Katherine K. Porterfield; Doug VanOrnum; Eric D. Roy. 2021. "Assessment of lime‐conditioned dairy manure fine solids captured using dissolved air flotation for fertilization in horticulture." Journal of Environmental Quality , no. : 1.

Journal article
Published: 16 February 2021 in Environmental Research Letters
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Nitrogen (N) is a vital input to crop production, but its excess use is a cause of environmental and human health problems in many parts of the world. In the United States (US), as in other nations, reducing N pollution remains challenging. Developing effective N policies and programs requires understanding links between cropland N balances (i.e. N inputs minus N harvested in crops) and potential contributing factors. We present novel insights into these links using a national county-level assessment and propose a criteria-scoring method to inform US N policy and programs. First, we characterize cropland N balances across the US in 2011–2013 and identify counties (~25%) where N input reductions are less likely to result in crop yield declines. Second, we identify agronomic, environmental, social, demographic, and economic factors correlated with N balance, as well as counties that are underperforming based on these characteristics. Finally, we employ criteria scoring and hot spot analysis to identify 20 spatial clusters of opportunity for improved cropland nitrogen management. These hot spots collectively account for ~63% of total surplus N balance for croplands but only ~24% of cropland area in the US. N flows for these hot spots indicate variable opportunities across the US landscape to improve cropland N balances by reducing N fertilizer use, better managing manure N, and/or increasing N use efficiency. These findings can guide future efforts to integrate N balance into regulatory and voluntary frameworks in US policy and programs.

ACS Style

Eric D Roy; Courtney R Hammond Wagner; Meredith T Niles. Hot spots of opportunity for improved cropland nitrogen management across the United States. Environmental Research Letters 2021, 16, 035004 .

AMA Style

Eric D Roy, Courtney R Hammond Wagner, Meredith T Niles. Hot spots of opportunity for improved cropland nitrogen management across the United States. Environmental Research Letters. 2021; 16 (3):035004.

Chicago/Turabian Style

Eric D Roy; Courtney R Hammond Wagner; Meredith T Niles. 2021. "Hot spots of opportunity for improved cropland nitrogen management across the United States." Environmental Research Letters 16, no. 3: 035004.

Research article
Published: 12 January 2021 in ACS ES&T Water
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Green stormwater infrastructure such as bioretention can reduce stormwater runoff volumes and trap sediments and pollutants. However, bioretention soil media can have limited capacity to retain phosphorus (P) or even be a P source, necessitating addition of P-sorbing materials. We investigated the potential trade-off between P removal by drinking water treatment residuals (DWTRs) and hydraulic conductivity to inform the design of bioretention media. Batch isotherm and flow-through column experiments showed that P removal varied greatly among three DWTRs and across methodologies, which has implications for design requirements. We also conducted a large column experiment to determine the hydraulic and P removal effects of amending bioretention media with solid and mixed layers of DWTRs. When DWTRs were applied to bioretention media, their impact on hydraulic conductivity and P removal depended on the layering strategy. Although DWTR addition in solid and mixed layer designs improved P removal, the solid layer restricted water flow and exhibited incomplete P removal, while the mixed layer had no effect on flow and removed nearly 100% of P inputs. We recommend that DWTRs be mixed with sand in bioretention media to simultaneously achieve stormwater drainage and P reduction goals.

ACS Style

Michael R. Ament; Stephanie E. Hurley; Mark Voorhees; Eric Perkins; Yongping Yuan; Joshua W. Faulkner; Eric D. Roy. Balancing Hydraulic Control and Phosphorus Removal in Bioretention Media Amended with Drinking Water Treatment Residuals. ACS ES&T Water 2021, 1, 688 -697.

AMA Style

Michael R. Ament, Stephanie E. Hurley, Mark Voorhees, Eric Perkins, Yongping Yuan, Joshua W. Faulkner, Eric D. Roy. Balancing Hydraulic Control and Phosphorus Removal in Bioretention Media Amended with Drinking Water Treatment Residuals. ACS ES&T Water. 2021; 1 (3):688-697.

Chicago/Turabian Style

Michael R. Ament; Stephanie E. Hurley; Mark Voorhees; Eric Perkins; Yongping Yuan; Joshua W. Faulkner; Eric D. Roy. 2021. "Balancing Hydraulic Control and Phosphorus Removal in Bioretention Media Amended with Drinking Water Treatment Residuals." ACS ES&T Water 1, no. 3: 688-697.

Erratum
Published: 14 December 2020 in Sustainability
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The authors would like to make the following correction for the published paper

ACS Style

Katherine Porterfield; Robert Joblin; Deborah Neher; Michael Curtis; Steve Dvorak; Donna Rizzo; Joshua Faulkner; Eric Roy. Erratum: Porterfield, K.K. et al. Upcycling Phosphorus Recovered from Anaerobically Digested Dairy Manure to Support Production of Vegetables and Flowers. Sustainability 2020, 12, 1139. Sustainability 2020, 12, 10441 .

AMA Style

Katherine Porterfield, Robert Joblin, Deborah Neher, Michael Curtis, Steve Dvorak, Donna Rizzo, Joshua Faulkner, Eric Roy. Erratum: Porterfield, K.K. et al. Upcycling Phosphorus Recovered from Anaerobically Digested Dairy Manure to Support Production of Vegetables and Flowers. Sustainability 2020, 12, 1139. Sustainability. 2020; 12 (24):10441.

Chicago/Turabian Style

Katherine Porterfield; Robert Joblin; Deborah Neher; Michael Curtis; Steve Dvorak; Donna Rizzo; Joshua Faulkner; Eric Roy. 2020. "Erratum: Porterfield, K.K. et al. Upcycling Phosphorus Recovered from Anaerobically Digested Dairy Manure to Support Production of Vegetables and Flowers. Sustainability 2020, 12, 1139." Sustainability 12, no. 24: 10441.

Journal article
Published: 05 February 2020 in Sustainability
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Dissolved air flotation (DAF) separates phosphorus (P)-rich fine solids from anaerobically digested dairy manure, creating opportunities to export surplus P to the marketplace as a bagged plant food product. Seedlings of tomato and marigold were amended at various volume per volume (v/v) ratios with plant foods consisting of fine solids upcycled (i.e., transformed into a higher quality product) by drying and blending with other organic residuals. A plate competition assay was conducted to assess the fine solids’ potential to suppress the plant pathogen Rhizoctonia solani. Plant foods were comprised of 2.0–2.1% N, 0.8–0.9% P and 0.6–0.8% K. Extractions indicated that plant foods contained a mixture of plant-available and slow-release P. At 6% v/v plant food, dry biomass of marigold and tomato were six-times greater than the unamended control and not significantly different from a market alternative treatment. Fine solids exhibited negligible potential to suppress R. solani. This study indicates that DAF-separated fine solids could be used to support horticulture, providing information for design of a circular economy approach to dairy manure nutrient management. Life cycle assessment and business model development for this nutrient recovery strategy are necessary next steps to further guide sustainability efforts.

ACS Style

Katherine K. Porterfield; Robert Joblin; Deborah A. Neher; Michael Curtis; Steve Dvorak; Donna M. Rizzo; Joshua W. Faulkner; Eric D. Roy. Upcycling Phosphorus Recovered from Anaerobically Digested Dairy Manure to Support Production of Vegetables and Flowers. Sustainability 2020, 12, 1139 .

AMA Style

Katherine K. Porterfield, Robert Joblin, Deborah A. Neher, Michael Curtis, Steve Dvorak, Donna M. Rizzo, Joshua W. Faulkner, Eric D. Roy. Upcycling Phosphorus Recovered from Anaerobically Digested Dairy Manure to Support Production of Vegetables and Flowers. Sustainability. 2020; 12 (3):1139.

Chicago/Turabian Style

Katherine K. Porterfield; Robert Joblin; Deborah A. Neher; Michael Curtis; Steve Dvorak; Donna M. Rizzo; Joshua W. Faulkner; Eric D. Roy. 2020. "Upcycling Phosphorus Recovered from Anaerobically Digested Dairy Manure to Support Production of Vegetables and Flowers." Sustainability 12, no. 3: 1139.

Research article
Published: 09 January 2020 in ACS Sustainable Chemistry & Engineering
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Digestate application to soils located near anaerobic digesters can potentially contribute to nutrient loss to downstream freshwater ecosystems and associated eutrophication. However, it is cost prohibitive to transport digestate to crop production areas further from digesters due to high water content. We evaluated the potential to recover phosphorus (P), as well as nitrogen (N) and potassium (K), from dairy manure digestate using dissolved air flotation (DAF) to separate fine solids. We measured flow rates and collected influent and effluent samples on 45 dates spanning 3.5 months from a DAF system fed by post-screw press digestate on a Vermont dairy farm. Separated fine solids recovered during the initiation period contained 29 ± 3% of N, 71 ± 18% of P and 11 ± 2% of K from the influent. At full operational capability, the DAF system captured 36 ± 2% of N, 85 ± 12% of P and 11 ± 1% of K from the influent in the separated fine solids. These findings indicate that most P remaining in post-screw press dairy manure digestate can be recovered using DAF while remaining effluent has an expanded range of use options due to a three-fold increase in the N:P ratio.

ACS Style

Katherine K. Porterfield; Joshua Faulkner; Eric D. Roy. Nutrient Recovery from Anaerobically Digested Dairy Manure Using Dissolved Air Flotation (DAF). ACS Sustainable Chemistry & Engineering 2020, 8, 1964 -1970.

AMA Style

Katherine K. Porterfield, Joshua Faulkner, Eric D. Roy. Nutrient Recovery from Anaerobically Digested Dairy Manure Using Dissolved Air Flotation (DAF). ACS Sustainable Chemistry & Engineering. 2020; 8 (4):1964-1970.

Chicago/Turabian Style

Katherine K. Porterfield; Joshua Faulkner; Eric D. Roy. 2020. "Nutrient Recovery from Anaerobically Digested Dairy Manure Using Dissolved Air Flotation (DAF)." ACS Sustainable Chemistry & Engineering 8, no. 4: 1964-1970.

Original research article
Published: 01 January 2020 in Agrosystems, Geosciences & Environment
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Oxisol soils with high P sorption capacity are widespread in Brazil, which is the world's second largest producer of soybean [Glycine max (L.) Merr.]. To counter low P availability within highly weathered soils, Brazilian soybean producers commonly fertilize with approximately twice as much P as is harvested in soybean. This has led to the accumulation of P in the soil, especially during the 2000s and 2010s, but the degree to which producers can capitalize on this residual soil P stock to offset fertilizer inputs remains unclear. We tested the effect of residual soil P in a field trial in Mato Grosso, Brazil on a field that has been fertilized for a decade. We grew soybean under three P treatments: 0, 50, and 100% of the farm's standard P fertilization rate for soybean (38 kg P ha−1 yr−1). This experiment was conducted for one growing season on two sites within the same farm field that had different soil texture, Al2O3 + Fe2O3 (R2O3), soil test P, and degree of P saturation. Soybean yield on the soil with greater clay content and R2O3 showed yield declines under reduced P input but yields on sandier soils that had higher soil test P were unaffected by reduced P inputs. These results highlight opportunities to enhance P fertilizer use efficiency in intensive tropical agriculture on highly weathered soils by using site‐specific soil fertility management to harness residual soil P.

ACS Style

Lauren P. Bomeisl; Christopher Neill; Stephen Porder; Carlos E.P. Cerri; Paulo M. Brando; Eric D. Roy. Tropical soybean yield response to reduced or zero phosphorus fertilization depends on soils. Agrosystems, Geosciences & Environment 2020, 3, 1 .

AMA Style

Lauren P. Bomeisl, Christopher Neill, Stephen Porder, Carlos E.P. Cerri, Paulo M. Brando, Eric D. Roy. Tropical soybean yield response to reduced or zero phosphorus fertilization depends on soils. Agrosystems, Geosciences & Environment. 2020; 3 (1):1.

Chicago/Turabian Style

Lauren P. Bomeisl; Christopher Neill; Stephen Porder; Carlos E.P. Cerri; Paulo M. Brando; Eric D. Roy. 2020. "Tropical soybean yield response to reduced or zero phosphorus fertilization depends on soils." Agrosystems, Geosciences & Environment 3, no. 1: 1.

Short communication
Published: 04 December 2019 in Waste and Biomass Valorization
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Anaerobic co-digestion of dairy manure and food wastes is increasing in the New England region of the United States because of policy measures intended to divert organic materials from landfills, reduce greenhouse gas emissions, and increase renewable biogas energy production. The sustainability of this approach depends on the management and valorization of remaining solid and liquid residues (i.e., digestates) after anaerobic digestion. Few studies have characterized digestates derived from combined dairy manure and food waste feedstocks. In this study, we analyzed screw-press separated liquid and solid digestates from 6 of 26 (23%) operational full-scale facilities in New England. We quantified multiple pools of nitrogen and phosphorus in these materials, with results suggesting that, in most cases, these nutrients largely exist in forms that can be recycled via slow-release fertilization, with smaller fractions in forms more easily lost to the environment. Furthermore, we found that solid digestates can inhibit mycelial growth of a common soilborne fungal pathogen, Rhizoctonia solani, suggesting potential to manage resident soil pathogens. Capitalizing on both nutrient recycling and pathogen suppression co-benefits will likely be useful in digestate valorization efforts.

ACS Style

Brendan J. O’Brien; Deborah A. Neher; Eric D. Roy. Nutrient and Pathogen Suppression Properties of Anaerobic Digestates from Dairy Manure and Food Waste Feedstocks. Waste and Biomass Valorization 2019, 11, 6565 -6573.

AMA Style

Brendan J. O’Brien, Deborah A. Neher, Eric D. Roy. Nutrient and Pathogen Suppression Properties of Anaerobic Digestates from Dairy Manure and Food Waste Feedstocks. Waste and Biomass Valorization. 2019; 11 (12):6565-6573.

Chicago/Turabian Style

Brendan J. O’Brien; Deborah A. Neher; Eric D. Roy. 2019. "Nutrient and Pathogen Suppression Properties of Anaerobic Digestates from Dairy Manure and Food Waste Feedstocks." Waste and Biomass Valorization 11, no. 12: 6565-6573.

Data note
Published: 30 August 2019 in BMC Research Notes
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Crop production is an important variable in social, economic and environmental analyses. There is an abundance of crop data available for the United States, but we lack a typology of county-level crop production that accounts for production similarities in counties across the country. We fill this gap with a county-level classification of crop production with ten mutually exclusive categories across the contiguous United States. To create the typology we ran a cluster analysis on acreage data for 21 key crops from the United States Department of Agriculture’s 2012 Agricultural Census. Prior to clustering, we estimated undisclosed county acreage values, controlled for acreage in other crop types, and removed counties with low agricultural production to produce proportional scores for each crop type in each county. We used proportional scores to control for the influence of county size in the cluster analysis and used internal and stability measures to validate the analysis. The final dataset features 2922 counties. Future research can leverage this typology as an input for county- or regional-level analysis.

ACS Style

Courtney R. Hammond Wagner; Meredith T. Niles; Eric D. Roy. US county-level agricultural crop production typology. BMC Research Notes 2019, 12, 1 -3.

AMA Style

Courtney R. Hammond Wagner, Meredith T. Niles, Eric D. Roy. US county-level agricultural crop production typology. BMC Research Notes. 2019; 12 (1):1-3.

Chicago/Turabian Style

Courtney R. Hammond Wagner; Meredith T. Niles; Eric D. Roy. 2019. "US county-level agricultural crop production typology." BMC Research Notes 12, no. 1: 1-3.

Preprint
Published: 20 August 2019
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Anaerobic co-digestion of dairy manure and food wastes is increasing in the New England region of the United States because of policy measures intended to divert organic materials from landfills, reduce greenhouse gas emissions, and increase renewable biogas energy production. The sustainability of this approach depends on the management and valorization of remaining solid and liquid residues (i.e., digestates) after anaerobic digestion. Few studies have characterized digestates derived from combined dairy manure and food waste feedstocks. In this study, we analyzed screw-press separated liquid and solid digestates from 6 of 26 (23%) operational full-scale facilities in New England. We quantified multiple pools of nitrogen and phosphorus in these materials, with results suggesting that in most cases these nutrients largely exist in forms that can be recycled via slow-release fertilization, with smaller fractions in forms more easily lost to the environment. Furthermore, we found that solid digestates can inhibit mycelial growth of a common soilborne fungal pathogen, Rhizoctonia solani, suggesting potential to manage resident soil pathogens. Capitalizing on both nutrient recycling and pathogen suppression co-benefits will likely be useful in digestate valorization efforts.

ACS Style

Brendan J O'brien; Deborah A Neher; Eric D Roy. Nutrient and pathogen suppression properties of anaerobic digestates from dairy manure and food waste feedstocks. 2019, 1 .

AMA Style

Brendan J O'brien, Deborah A Neher, Eric D Roy. Nutrient and pathogen suppression properties of anaerobic digestates from dairy manure and food waste feedstocks. . 2019; ():1.

Chicago/Turabian Style

Brendan J O'brien; Deborah A Neher; Eric D Roy. 2019. "Nutrient and pathogen suppression properties of anaerobic digestates from dairy manure and food waste feedstocks." , no. : 1.

Preprint
Published: 20 August 2019
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Anaerobic co-digestion of dairy manure and food wastes is increasing in the New England region of the United States because of policy measures intended to divert organic materials from landfills, reduce greenhouse gas emissions, and increase renewable biogas energy production. The sustainability of this approach depends on the management and valorization of remaining solid and liquid residues (i.e., digestates) after anaerobic digestion. Few studies have characterized digestates derived from combined dairy manure and food waste feedstocks. In this study, we analyzed screw-press separated liquid and solid digestates from 6 of 26 (23%) operational full-scale facilities in New England. We quantified multiple pools of nitrogen and phosphorus in these materials, with results suggesting that in most cases these nutrients largely exist in forms that can be recycled via slow-release fertilization, with smaller fractions in forms more easily lost to the environment. Furthermore, we found that solid digestates can inhibit mycelial growth of a common soilborne fungal pathogen, Rhizoctonia solani, suggesting potential to manage resident soil pathogens. Capitalizing on both nutrient recycling and pathogen suppression co-benefits will likely be useful in digestate valorization efforts.

ACS Style

Brendan J O'brien; Deborah A Neher; Eric D Roy. Nutrient and pathogen suppression properties of anaerobic digestates from dairy manure and food waste feedstocks. 2019, 1 .

AMA Style

Brendan J O'brien, Deborah A Neher, Eric D Roy. Nutrient and pathogen suppression properties of anaerobic digestates from dairy manure and food waste feedstocks. . 2019; ():1.

Chicago/Turabian Style

Brendan J O'brien; Deborah A Neher; Eric D Roy. 2019. "Nutrient and pathogen suppression properties of anaerobic digestates from dairy manure and food waste feedstocks." , no. : 1.

Journal article
Published: 01 April 2019 in Bioresource Technology
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State-level policies in the northeast United States require diversion of organic materials away from landfills, leading to increased anaerobic co-digestion of dairy manure and food waste. In addition to biogas, anaerobic digestion produces separated solid and liquid digestates. Solid digestates in the region are typically recycled as animal bedding before returning to the digester and liquids are used to fertilize local soils. Repeated land application of nutrients can contribute to eutrophication risk over time and alternative models are needed to convert digestates into valuable export products. We tested solid digestates derived from dairy manure and food waste as substrate ingredients in the cultivation of Pleurotus ostreatus. We show these materials can be used to offset non-local substrate ingredients while achieving mushroom yields comparable to commercial recipes. This strategy could divert nutrients away from land adjacent to digesters and into safe, protein-rich food, while producing a useful spent mushroom substrate product.

ACS Style

Brendan J. O'Brien; Eric Milligan; Jon Carver; Eric D. Roy. Integrating anaerobic co-digestion of dairy manure and food waste with cultivation of edible mushrooms for nutrient recovery. Bioresource Technology 2019, 285, 121312 .

AMA Style

Brendan J. O'Brien, Eric Milligan, Jon Carver, Eric D. Roy. Integrating anaerobic co-digestion of dairy manure and food waste with cultivation of edible mushrooms for nutrient recovery. Bioresource Technology. 2019; 285 ():121312.

Chicago/Turabian Style

Brendan J. O'Brien; Eric Milligan; Jon Carver; Eric D. Roy. 2019. "Integrating anaerobic co-digestion of dairy manure and food waste with cultivation of edible mushrooms for nutrient recovery." Bioresource Technology 285, no. : 121312.

Research article
Published: 18 April 2018 in PLOS ONE
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Improving diet quality while simultaneously reducing environmental impact is a critical focus globally. Metrics linking diet quality and sustainability have typically focused on a limited suite of indicators, and have not included food waste. To address this important research gap, we examine the relationship between food waste, diet quality, nutrient waste, and multiple measures of sustainability: use of cropland, irrigation water, pesticides, and fertilizers. Data on food intake, food waste, and application rates of agricultural amendments were collected from diverse US government sources. Diet quality was assessed using the Healthy Eating Index-2015. A biophysical simulation model was used to estimate the amount of cropland associated with wasted food. This analysis finds that US consumers wasted 422g of food per person daily, with 30 million acres of cropland used to produce this food every year. This accounts for 30% of daily calories available for consumption, one-quarter of daily food (by weight) available for consumption, and 7% of annual cropland acreage. Higher quality diets were associated with greater amounts of food waste and greater amounts of wasted irrigation water and pesticides, but less cropland waste. This is largely due to fruits and vegetables, which are health-promoting and require small amounts of cropland, but require substantial amounts of agricultural inputs. These results suggest that simultaneous efforts to improve diet quality and reduce food waste are necessary. Increasing consumers’ knowledge about how to prepare and store fruits and vegetables will be one of the practical solutions to reducing food waste.

ACS Style

Zach Conrad; Meredith T. Niles; Deborah A. Neher; Eric D. Roy; Nicole E. Tichenor; Lisa Jahns. Relationship between food waste, diet quality, and environmental sustainability. PLOS ONE 2018, 13, e0195405 .

AMA Style

Zach Conrad, Meredith T. Niles, Deborah A. Neher, Eric D. Roy, Nicole E. Tichenor, Lisa Jahns. Relationship between food waste, diet quality, and environmental sustainability. PLOS ONE. 2018; 13 (4):e0195405.

Chicago/Turabian Style

Zach Conrad; Meredith T. Niles; Deborah A. Neher; Eric D. Roy; Nicole E. Tichenor; Lisa Jahns. 2018. "Relationship between food waste, diet quality, and environmental sustainability." PLOS ONE 13, no. 4: e0195405.

Journal article
Published: 01 March 2018 in Science of The Total Environment
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Over 25% of Mississippi River delta plain (MRDP) wetlands were lost over the past century. There is currently a major effort to restore the MRDP focused on a 50-year time horizon, a period during which the energy system and climate will change dramatically. We used a calibrated MRDP marsh elevation model to assess the costs of hydraulic dredging to sustain wetlands from 2016 to 2066 and 2016 to 2100 under a range of scenarios for sea level rise, energy price, and management regimes. We developed a subroutine to simulate dredging costs based on the price of crude oil and a project efficiency factor. Crude oil prices were projected using forecasts from global energy models. The costs to sustain marsh between 2016 and 2100 changed from $128,000/ha in the no change scenario to ~$1,010,000/ha in the worst-case scenario for sea level rise and energy price, an ~8-fold increase. Increasing suspended sediment concentrations, which is possible using managed river diversions, raised created marsh lifespan and decreased long term dredging costs. Created marsh lifespan changed nonlinearly with dredging fill elevation and suspended sediment level. Cost effectiveness of marsh creation and nourishment can be optimized by adjusting dredging fill elevation to the local sediment regime. Regardless of management scenario, sustaining the MRDP with hydraulic dredging suffered declining returns on investment due to the convergence of energy and climate trends. Marsh creation will likely become unaffordable in the mid to late 21st century, especially if river sediment diversions are not constructed before 2030. We recommend that environmental managers take into consideration coupled energy and climate scenarios for long-term risk assessments and adjust restoration goals accordingly.

ACS Style

Adrian R.H. Wiegman; John W. Day; Christopher F. D'Elia; Jeffrey S. Rutherford; James T. Morris; Eric Roy; Robert R. Lane; David E. Dismukes; Brian F. Snyder. Modeling impacts of sea-level rise, oil price, and management strategy on the costs of sustaining Mississippi delta marshes with hydraulic dredging. Science of The Total Environment 2018, 618, 1547 -1559.

AMA Style

Adrian R.H. Wiegman, John W. Day, Christopher F. D'Elia, Jeffrey S. Rutherford, James T. Morris, Eric Roy, Robert R. Lane, David E. Dismukes, Brian F. Snyder. Modeling impacts of sea-level rise, oil price, and management strategy on the costs of sustaining Mississippi delta marshes with hydraulic dredging. Science of The Total Environment. 2018; 618 ():1547-1559.

Chicago/Turabian Style

Adrian R.H. Wiegman; John W. Day; Christopher F. D'Elia; Jeffrey S. Rutherford; James T. Morris; Eric Roy; Robert R. Lane; David E. Dismukes; Brian F. Snyder. 2018. "Modeling impacts of sea-level rise, oil price, and management strategy on the costs of sustaining Mississippi delta marshes with hydraulic dredging." Science of The Total Environment 618, no. : 1547-1559.

Journal article
Published: 01 December 2017 in Science of The Total Environment
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Ongoing deterioration and loss of wetlands in the Mississippi River delta threatens the survival of Louisiana's coastal ecosystems and human settlements. In response, the State of Louisiana has proposed a $50 billion, 50-year restoration program. A central piece of this program is the reintroduction of Mississippi River water into the deltaic plain using managed diversions that mimic natural flood pulses. These diversions would transport critically needed sediment, but also deliver large nutrient loads. Coastal eutrophication is therefore a concern, particularly blooms of toxin-producing cyanobacteria. The Bonnet Carré Spillway (BCS) is an existing large flood diversion that protects New Orleans and provides an opportunity to investigate diversion nutrient transport. Here, we quantify sediment phosphorus (P) deposited by the BCS for the first time, and use a sequential P fractionation scheme to evaluate the likelihood of future sediment P release to the water column of the Lake Pontchartrain Estuary. In 2011, we collected sediment cores in the estuary for determination of P fractions before and after the discharge of 21.9km(3) of river water through the BCS in just under 6weeks. We observed the greatest net increases in sediment total P, inorganic P forms, and more labile organic P in the region near the inflow. We estimate that the diversion deposited ≥5000 metric tons of P in the sediments of the Lake Pontchartrain Estuary. The sum of readily available inorganic P, Fe/Al-bound inorganic P, and more labile organic P equaled approximately 20-30% of post-diversion sediment total P. These fractions are more likely to be released to the water column than the other sediment P forms we quantified. Diversion designs that encourage sedimentation in coastal marshes versus open bays can likely reduce the chances that deposited particulate P creates eutrophication risk.

ACS Style

Eric D. Roy; Nhan T. Nguyen; John R. White. Changes in estuarine sediment phosphorus fractions during a large-scale Mississippi River diversion. Science of The Total Environment 2017, 609, 1248 -1257.

AMA Style

Eric D. Roy, Nhan T. Nguyen, John R. White. Changes in estuarine sediment phosphorus fractions during a large-scale Mississippi River diversion. Science of The Total Environment. 2017; 609 ():1248-1257.

Chicago/Turabian Style

Eric D. Roy; Nhan T. Nguyen; John R. White. 2017. "Changes in estuarine sediment phosphorus fractions during a large-scale Mississippi River diversion." Science of The Total Environment 609, no. : 1248-1257.

Journal article
Published: 01 November 2017 in Agriculture, Ecosystems & Environment
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ACS Style

Eric Roy; Edwin Willig; Peter D. Richards; Luiz Martinelli; Felipe Ferraz Vazquez; Lindomar Pegorini; Stephanie Spera; Stephen Porder. Soil phosphorus sorption capacity after three decades of intensive fertilization in Mato Grosso, Brazil. Agriculture, Ecosystems & Environment 2017, 249, 206 -214.

AMA Style

Eric Roy, Edwin Willig, Peter D. Richards, Luiz Martinelli, Felipe Ferraz Vazquez, Lindomar Pegorini, Stephanie Spera, Stephen Porder. Soil phosphorus sorption capacity after three decades of intensive fertilization in Mato Grosso, Brazil. Agriculture, Ecosystems & Environment. 2017; 249 ():206-214.

Chicago/Turabian Style

Eric Roy; Edwin Willig; Peter D. Richards; Luiz Martinelli; Felipe Ferraz Vazquez; Lindomar Pegorini; Stephanie Spera; Stephen Porder. 2017. "Soil phosphorus sorption capacity after three decades of intensive fertilization in Mato Grosso, Brazil." Agriculture, Ecosystems & Environment 249, no. : 206-214.

Review
Published: 01 January 2017 in Ecological Engineering
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ACS Style

Eric Roy. Phosphorus recovery and recycling with ecological engineering: A review. Ecological Engineering 2017, 98, 213 -227.

AMA Style

Eric Roy. Phosphorus recovery and recycling with ecological engineering: A review. Ecological Engineering. 2017; 98 ():213-227.

Chicago/Turabian Style

Eric Roy. 2017. "Phosphorus recovery and recycling with ecological engineering: A review." Ecological Engineering 98, no. : 213-227.

Journal article
Published: 01 June 2016 in Ecological Engineering
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ACS Style

Eric Roy; Emily A. Smith; Sibel Bargu; John R. White. Will Mississippi River diversions designed for coastal restoration cause harmful algal blooms? Ecological Engineering 2016, 91, 350 -364.

AMA Style

Eric Roy, Emily A. Smith, Sibel Bargu, John R. White. Will Mississippi River diversions designed for coastal restoration cause harmful algal blooms? Ecological Engineering. 2016; 91 ():350-364.

Chicago/Turabian Style

Eric Roy; Emily A. Smith; Sibel Bargu; John R. White. 2016. "Will Mississippi River diversions designed for coastal restoration cause harmful algal blooms?" Ecological Engineering 91, no. : 350-364.

Journal article
Published: 18 April 2016 in Nature Plants
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Agricultural intensification in the tropics is one way to meet rising global food demand in coming decades1,2. Although this strategy can potentially spare land from conversion to agriculture3, it relies on large material inputs. Here we quantify one such material cost, the phosphorus fertilizer required to intensify global crop production atop phosphorus-fixing soils and achieve yields similar to productive temperate agriculture. Phosphorus-fixing soils occur mainly in the tropics, and render added phosphorus less available to crops4,5. We estimate that intensification of the 8–12% of global croplands overlying phosphorus-fixing soils in 2005 would require 1–4 Tg P yr–1 to overcome phosphorus fixation, equivalent to 8–25% of global inorganic phosphorus fertilizer consumption that year. This imposed phosphorus ‘tax’ is in addition to phosphorus added to soils and subsequently harvested in crops, and doubles (2–7 Tg P yr–1) for scenarios of cropland extent in 20506. Our estimates are informed by local-, state- and national-scale investigations in Brazil, where, more than any other tropical country, low-yielding agriculture has been replaced by intensive production. In the 11 major Brazilian agricultural states, the surplus of added inorganic fertilizer phosphorus retained by soils post harvest is strongly correlated with the fraction of cropland overlying phosphorus-fixing soils (r2 = 0.84, p < 0.001). Our interviews with 49 farmers in the Brazilian state of Mato Grosso, which produces 8% of the world's soybeans mostly on phosphorus-fixing soils, suggest this phosphorus surplus is required even after three decades of high phosphorus inputs. Our findings in Brazil highlight the need for better understanding of long-term soil phosphorus fixation elsewhere in the tropics. Strategies beyond liming, which is currently widespread in Brazil, are needed to reduce phosphorus retention by phosphorus-fixing soils to better manage the Earth's finite phosphate rock supplies and move towards more sustainable agricultural production.

ACS Style

Eric Roy; Peter D. Richards; Luiz Martinelli; Luciana Della Coletta; Silvia Rafaela Machado Lins; Felipe Ferraz Vazquez; Edwin Willig; Stephanie Spera; Leah K. VanWey; Stephen Porder. The phosphorus cost of agricultural intensification in the tropics. Nature Plants 2016, 2, 16043 .

AMA Style

Eric Roy, Peter D. Richards, Luiz Martinelli, Luciana Della Coletta, Silvia Rafaela Machado Lins, Felipe Ferraz Vazquez, Edwin Willig, Stephanie Spera, Leah K. VanWey, Stephen Porder. The phosphorus cost of agricultural intensification in the tropics. Nature Plants. 2016; 2 (5):16043.

Chicago/Turabian Style

Eric Roy; Peter D. Richards; Luiz Martinelli; Luciana Della Coletta; Silvia Rafaela Machado Lins; Felipe Ferraz Vazquez; Edwin Willig; Stephanie Spera; Leah K. VanWey; Stephen Porder. 2016. "The phosphorus cost of agricultural intensification in the tropics." Nature Plants 2, no. 5: 16043.

Book chapter
Published: 26 October 2015 in SSSA Book Series
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Ammonification, or the mineralization of organic N, in wetland soils regulates the bioavailability of N in both soils and the overlying water column. Several environmental factors including temperature, O2 availability, microbial activity, and limiting nutrients influence the rates of organic N mineralization, leading to variability among wetland environments. In this chapter, we describe two analytical methods that provide measures of the N mineralization potential in wetland soils. The method described for measuring potentially mineralizable N utilizes 10-d anaerobic incubations to determine the relative increase in N availability from ammonification over time. A second method to measure substrate-induced N mineralization removes rate-limiting controls on mineralization by providing a readily hydrolyzable substrate and rapidly captures the relative activity of the portion of the microbial pool responsible for N mineralization. Methods are described from reagent preparation through incubations, extractions, and calculations. Copyright © 2013. . Copyright © 2013 Soil Science Society of America, 5585 Guilford Road, Madison, WI 53711-5801, USA.

ACS Style

Eric D. Roy; John R. White. Measurements of Nitrogen Mineralization Potential in Wetland Soils. SSSA Book Series 2015, sssabookse, 465 -472.

AMA Style

Eric D. Roy, John R. White. Measurements of Nitrogen Mineralization Potential in Wetland Soils. SSSA Book Series. 2015; sssabookse (methodsinb):465-472.

Chicago/Turabian Style

Eric D. Roy; John R. White. 2015. "Measurements of Nitrogen Mineralization Potential in Wetland Soils." SSSA Book Series sssabookse, no. methodsinb: 465-472.