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Journal of Environmental Quality : Just Published


Accepted, edited articles are published here after author proofing to provide rapid publication and better access to the newest research. Articles are compiled into issues at dl.sciencesocieties.org/publications/jeq, which includes the complete archive.

Citation | Articles posted here are considered published and may be cited by the doi.

Maguire, R.O., P.J. A. Kleinman, C.J. Dell, D.B. Beegle, R.C. Brandt, J.M. McGrath, and Q.M. Ketterings. 2011. Manure application technology in reduced tillage and forage systems: A review. J. Environ. Qual. doi: 10.2134/jeq2009.0228

Current issue: J. Environ. Qual. 45(3)


    • Rodney T. Venterea, Jeffrey A. Coulter and Michael S. Dolan
      Evaluation of Intensive “4R” Strategies for Decreasing Nitrous Oxide Emissions and Nitrogen Surplus in Rainfed Corn

      The “4R” approach of using the right rate, right source, right timing, and right placement is an accepted framework for increasing crop N use efficiency. However, modifying only one 4R component does not consistently reduce nitrous oxide (N2O) emissions. Our objective was to determine if N fertilizer applied in three split applications (Sp), by itself or combined with changes in N source and rate, could improve N recovery efficiency (NRE) and N surplus (NS) and decrease N2O emissions. Over two corn (Zea mays L.) growing seasons in Minnesota, N2O emissions ranged from 0.6 to 0.9 kg N ha−1. (continued)

      Core Ideas:
      • Split application by itself did not decrease N2O compared with single application.
      • Microbial inhibitors did not decrease N2O unless combined with reduced N rate.
      • Some treatments increased N recovery efficiency but did not reduce N2O.
      • N2O was more strongly related to N surplus on a grain- compared with whole-plant basis.
      • Strategies that modify more than one 4R component may be needed to reduce direct N2O.

      Published: May 20, 2016

    • Steven L. Trabue, Brian J. Kerr, Bradley L. Bearson, Manhoi Hur, Timothy Parkin, Eve S. Wurtele and Cherrie J. Ziemer
      Microbial Community and Chemical Characteristics of Swine Manure during Maturation

      Swine diet formulations have the potential to lower animal emissions, including odor and ammonia (NH3). The purpose of this study was to determine the impact of manure storage duration on manure chemical and microbial properties in swine feeding trials. Three groups of 12 pigs were fed a standard corn–soybean meal diet over a 13-wk period. Urine and feces were collected at each feeding and transferred to 12 manure storage tanks. (continued)

      Core Ideas:
      • Emissions of odorants from manure stabilized after 5 wk in a swine feeding trial.
      • Microbial numbers and species diversity declined significantly with manure storage.
      • Manure chemical properties influence the microbial community metabolic functions.
      • Emissions of GHG from manure never stabilized throughout the 13-wk feeding trial.

      Published: May 6, 2016

    • S. M. McGinn, H. H. Janzen, T. W. Coates, K. A. Beauchemin and T. K. Flesch
      Ammonia Emission from a Beef Cattle Feedlot and Its Local Dry Deposition and Re-Emission

      Ammonia (NH3) volatized from livestock manure is affiliated with ecosystem and human health concerns and decreased fertilizer value of manure and can also be an indirect source of greenhouse gas. Beef cattle feedlots, where thousands of cattle are grouped together to enable greater control of feed management and production, are hot spots in the agricultural landscape for NH3 emissions. Quantifying the feedlot NH3 emissions is a difficult task, partly due to the reactive nature of NH3 within and surrounding the feedlot. Our study used a dispersion model coupled to field measurements to derive NH3 emissions from a feedlot in southern Alberta, Canada. (continued)

      Core Ideas:
      • Beef feedlots are “hot spots” of ammonia emissions in the landscape.
      • A significant fraction of the emitted ammonia is deposited to local land.
      • Nitrogen fate of emitted ammonia is dynamic.

      Published: April 22, 2016

    • Mario Tenuta, Xiaopeng Gao, Donald N. Flaten and Brian D. Amiro
      Lower Nitrous Oxide Emissions from Anhydrous Ammonia Application Prior to Soil Freezing in Late Fall Than Spring Pre-Plant Application

      Fall application of anhydrous ammonia in Manitoba is common but its impact on nitrous oxide (N2O) emissions is not well known. A 2-yr study compared application before freeze-up in late fall to spring pre-plant application of anhydrous ammonia on nitrous oxide (N2O) emissions from a clay soil in the Red River Valley, Manitoba. Spring wheat (Triticum aestivum L.) and corn (Zea mays L.) were grown on two 4-ha fields in 2011 and 2012, respectively. Field-scale flux of N2O was measured using a flux-gradient micrometeorological approach. (continued)

      Core Ideas:
      • Late-fall ammonia application prior to freeze-up did not induce N2O emissions over winter.
      • Late-fall application did increase N2O emissions during thaw the following year.
      • Despite lower area-based emission in the first study year, poor yield increased yield-scaled emissions.
      • For the second study year, yield-scaled emissions were similar for application treatments.

      Published: April 1, 2016

    • Daniel N. Miller, Mindy J. Spiehs, Vincent H. Varel, Bryan L. Woodbury, James E. Wells and Elaine D. Berry
      Distillers By-Product Cattle Diets Enhance Reduced Sulfur Gas Fluxes from Feedlot Soils and Manures

      Total reduced sulfur (TRS) emissions from animal feeding operations are a concern with increased feeding of high-sulfur distillers by-products. Three feeding trials were conducted to evaluate feeding wet distillers grain plus solubles (WDGS) on TRS fluxes. Fresh manure was collected three times during Feeding Trial 1 from cattle fed 0, 20, 40, and 60% WDGS. Fluxes of TRS from 40 and 60% WDGS manures were 3- to 13-fold greater than the 0 and 20% WDGS manures during the first two periods. (continued)

      Core Ideas:
      • Distillers grains diets increase manure sulfur fluxes.
      • Manure sulfur fluxes are greater than soil sulfur fluxes.
      • Soil fluxes are greater from wet, manure-impacted sites.

      Published: April 1, 2016


    • Ghulam Haider, Diedrich Steffens, Christoph Müller and Claudia I. Kammann
      Standard Extraction Methods May Underestimate Nitrate Stocks Captured by Field-Aged Biochar

      Biochar (BC) has been shown to increase the potential for N retention in agricultural soils. However, the form of N retained and its strength of retention are poorly understood. Here, we examined if the N retained could be readily extractable by standard methods and if the amount of N retained varied with BC field ageing. We investigated soil and field-aged BC (BCaged) particles of a field experiment (sandy soil amended with BC at 0, 15, and 30 t ha−1) under two watering regimes (irrigated and rain-fed). (continued)

      Core Ideas:
      • Biochar reduced nitrate leaching from temperate sandy soil in the field.
      • Biochar particles captured nitrate amounts several-fold greater than found in soil.
      • Standard extraction methods may not retrieve all biochar-captured nitrate.
      • Field-aged biochar captured much more nitrate than ammonium.
      • Captured nitrate amounts were independent of the biochar particle size.

      Published: April 1, 2016


    • Tyler J. Hengen, Heidi L. Sieverding, Noel A. Cole, Jay M. Ham and James J. Stone
      Eco-Efficiency Model for Evaluating Feedlot Rations in the Great Plains, United States

      Environmental impacts attributable to beef feedlot production provide an opportunity for economically linked efficiency optimization. Eco-efficiency models are used to optimize production and processes by connecting and quantifying environmental and economic impacts. An adaptable, objective eco-efficiency model was developed to assess the impacts of dietary rations on beef feedlot environmental and fiscal cost. The hybridized model used California Net Energy System modeling, life cycle assessment, principal component analyses (PCA), and economic analyses. (continued)

      Core Ideas:
      • Objective eco-efficiency scores can be produced using principal component analyses.
      • Large numbers of scenarios can be effectively assessed using eco-efficiency scoring.
      • Feedlot feed diets impact the sustainability of beef products.

      Published: April 29, 2016

    • Elia Scudiero, Scott M. Lesch and Dennis L. Corwin
      Validation of Sensor-Directed Spatial Simulated Annealing Soil Sampling Strategy

      Soil spatial variability has a profound influence on most agronomic and environmental processes at field and landscape scales, including site-specific management, vadose zone hydrology and transport, and soil quality. Mobile sensors are a practical means of mapping spatial variability because their measurements serve as a proxy for many soil properties, provided a sensor–soil calibration is conducted. A viable means of calibrating sensor measurements over soil properties is through linear regression modeling of sensor and target property data. In the present study, two sensor-directed, model-based, sampling scheme delineation methods were compared to validate recent applications of soil apparent electrical conductivity (ECa)-directed spatial simulated annealing against the more established ECa–directed response surface sampling design (RSSD) approach. (continued)

      Core Ideas:
      • Sensor-directed sampling is valuable for mapping soil properties using few samples.
      • Apparent electrical conductivity is a good proxy for soil salinity.
      • Spatial simulated annealing and response surface design sampling are compared.
      • ECa-directed SSA is a valuable sampling approach for soil science applications.

      Published: April 22, 2016

    • Amy S. Collick, Tamie L. Veith, Daniel R. Fuka, Peter J.A. Kleinman, Anthony R. Buda, Jennifer L. Weld, Ray B. Bryant, Peter A. Vadas, Mike J. White, R. Daren Harmel and Zachary M. Easton
      Improved Simulation of Edaphic and Manure Phosphorus Loss in SWAT

      Watershed models such as the Soil Water Assessment Tool (SWAT) and the Agricultural Policy Environmental EXtender (APEX) are widely used to assess the fate and transport of agricultural nutrient management practices on soluble and particulate phosphorus (P) loss in runoff. Soil P-cycling routines used in SWAT2012 revision 586, however, do not simulate the short-term effects of applying a concentrated source of soluble P, such as manure, to the soil surface where it is most vulnerable to runoff. We added a new set of soil P routines to SWAT2012 revision 586 to simulate surface-applied manure at field and subwatershed scales within Mahantango Creek watershed in south-central Pennsylvania. We corroborated the new P routines and standard P routines in two versions of SWAT (conventional SWAT, and a topographically driven variation called TopoSWAT) for a total of four modeling “treatments”. (continued)

      Core Ideas:
      • Dynamic manure P routines were added to the conventional SWAT model.
      • New P routines were corroborated in two versions of SWAT.
      • New P routines accurately simulated the 4R effects of manure management.

      Published: April 22, 2016


    • S. E. King, D. L. Osmond, J. Smith, M. R. Burchell, M. Dukes, R. O. Evans, S. Knies and S. Kunickis
      Effects of Riparian Buffer Vegetation and Width: A 12-Year Longitudinal Study

      Agricultural contributions of nitrogen are a serious concern for many water resources and have spurred the implementation of riparian buffer zones to reduce groundwater nitrate (NO3). The optimum design for buffers is subject to debate, and there are few long-term studies. The objective of this project was to determine the effectiveness over time (12 yr) of buffer types (trees, switchgrass, fescue, native, and a control) and buffer widths (8 and 15 m) by measuring groundwater NO3–N and dissolved organic carbon (DOC) trends. At the intermediate groundwater depth (1.5–2.1 m), NO3–N reduction effectiveness was 2.5 times greater (46 vs. (continued)

      Core Ideas:
      • Unique, long-term replicated riparian buffer study in the southeastern United States.
      • Long-term riparian buffer study from establishment through Year 12.
      • Effects of five different riparian-buffer vegetation types of nitrate reduction.

      Published: May 6, 2016


    • Yang Yang, Zhengchao Zhou, Yanying Bai, Wentao Jiao and Weiping Chen
      Trace Elements in Dominant Species of the Fenghe River, China: Their Relations to Environmental Factors

      The distribution of trace elements (TEs) in water, sediment, riparian soil and dominant plants was investigated in the Fenghe River, Northwestern China. The Fenghe River ecosystem was polluted with Cd, Cr, Hg and Pb. There was a high pollution risk in the midstream and downstream regions and the risk level for Cd was much higher than that of the other elements. The average values of bioconcentration coefficient for Cd and Zn were 2.21 and 1.75, respectively, indicating a large accumulation of Cd and Zn in the studied species. (continued)

      Core Ideas:
      • Trace elements posed high ecological risk in the Fenghe River system.
      • Four native species could be used for phytoremediation.
      • Dissolved NH3–N, NO3–N, TN, and TP drove elemental uptake by plants.
      • Soil elements and soil pH had major effect on plants uptake of elements.
      • Plant diversity was sensitive to the high level trace elements in the water habitats.

      Published: May 6, 2016

    • Katrin Matern and Tim Mansfeldt
      Chromium Release from a COPR-Contaminated Soil at Varying Water Content and Redox Conditions

      Many soils in the region of Kanpur, North India, are heavily affected by the leather industry and its upstream supplier sector, as indicated by elevated chromium (Cr) contents. Under reducing conditions—for instance, at water saturation after monsoon rain or flood irrigation—the dynamic and species distribution of Cr may be affected due to changes in redox potential (EH). In this study, the influence of EH on the speciation and release of Cr from a contaminated agricultural soil was investigated. A soil sample that was affected by hyperalkaline leachate from chromite ore processing residue, was taken and packed in soil columns, and subjected to a saturation–drainage–saturation cycle. (continued)

      Core Ideas:
      • Cr(VI) was highly mobile in the investigated soil.
      • High Cr(VI) concentration prevented the reduction of Mn and Fe.
      • Cr(VI) was mobilized under oxidizing soil conditions.
      • Cr was immobilized under moderately reducing soil conditions.

      Published: April 8, 2016


    • Andrew L. Birch, Ryan E. Emanuel, April L. James and Elizabeth Guthrie Nichols
      Hydrologic Impacts of Municipal Wastewater Irrigation to a Temperate Forest Watershed

      Land application of municipal wastewater to managed forests is an important treatment and water reuse technology used globally, but the hydrological processes of these systems are not well characterized for temperate areas with annual rainfall of 1200 mm or greater. This study evaluated the impact of municipal wastewater irrigation to the local water balance at a 3000-ha land application facility where secondary-treated wastewater is land applied to a mixed hardwood–pine forest over 900 ha. Stable isotopes of hydrogen (2H) and oxygen (18O), chloride concentrations, and specific conductance were used in combination with hydrometric measurements to estimate the wastewater composition in groundwater, surface water, and at the watershed outlet during dry and wet seasonal periods and during one large rainfall event. Wastewater and water bodies receiving irrigation were found to have significantly higher δ2H, δ18O, specific conductance, and chloride concentrations. (continued)

      Core Ideas:
      • Municipal wastewater irrigation to forested lands can substantially alter the local water cycle.
      • An aquifer receiving spray irrigation was found to be largely composed of wastewater (47–73%).
      • Influence of spray irrigation on receiving water bodies varies with respect to flow conditions.

      Published: May 20, 2016

    • Nitin K. Singh, Wilmer M. Reyes, Emily S. Bernhardt, Ruchi Bhattacharya, Judy L. Meyer, Jennifer D. Knoepp and Ryan E. Emanuel
      Hydro-Climatological Influences on Long-Term Dissolved Organic Carbon in a Mountain Stream of the Southeastern United States

      In the past decade, significant increases in surface water dissolved organic carbon (DOC) have been reported for large aquatic ecosystems of the Northern Hemisphere and have been attributed variously to global warming, altered hydrologic conditions, and atmospheric deposition, among other factors. We analyzed a 25-yr DOC record (1988–2012) available for a forested headwater stream in the United States and documented two distinct regimes of stream DOC trends. From 1988 to 2001, annual mean volume-weighted DOC concentration (DOCvw, mg L−1) and annual DOC flux (kg ha−1 yr−1) declined by 34 and 56%, respectively. During 1997 to 2012, the decline in DOCvw and DOC flux increased by 141 and 165%, respectively. (continued)

      Core Ideas:
      • Long-term records show a steady decline in stream DOC followed by a steady increase.
      • Declining runoff and changes in storm timing and intensity point to hydro-climatological drivers.
      • Neither temperature nor atmospheric deposition explained bidirectionality of trends.

      Published: May 13, 2016

    • R. W. McDowell, M. Norris and N. Cox
      Using the Provenance of Sediment and Bioavailable Phosphorus to Help Mitigate Water Quality Impact in an Agricultural Catchment

      The quality and health of surface waters can be impaired by sediment and sediment-bound phosphorus (P). The Waituna Lagoon catchment in southern New Zealand has undergone agricultural intensification that has been linked to increases in sediment and sediment-bound bioavailable P (BAP) in the lagoon. Time-integrated samplers trapped suspended sediment from the water column, and their geochemical signature was compared with likely sources (stream banks, stream beds, topsoil, and subsoil) in each of the lagoon’s contributing streams and rivers. The proportion of BAP, but not necessarily total P, within trapped sediment was much greater in samples from the Moffat and Carran Creeks than from the Waituna Creek, probably due to the erosion of organic-rich soils that had little capacity to retain P compared with the more mineral soils of the Waituna Creek. (continued)

      Core Ideas:
      • The water quality of coastal lagoons is affected by sediment and P inputs.
      • Knowing the provenance of sediment and BAP can help target strategies to mitigate loss.
      • Organic-rich soils lost more BAP but less sediment than mineral soils.
      • Mitigating erosion and P form mineral soils should focus on stream banks and topsoil.
      • Losses from Organic soils were from many sources; overall P inputs should be lowered.

      Published: May 6, 2016

    • Mark B. David, Lowell E. Gentry and Corey A. Mitchell
      Riverine Response of Sulfate to Declining Atmospheric Sulfur Deposition in Agricultural Watersheds

      Sulfur received extensive study as an input to terrestrial ecosystems from acidic deposition during the 1980s. With declining S deposition inputs across the eastern United States, there have been many studies evaluating ecosystem response, with the exception of agricultural watersheds. We used long-term (22 and 18 yr) sulfate concentration data from two rivers and recent (6 yr) data from a third river to better understand cycling and transport of S in agricultural, tile-drained watersheds. Sulfate concentrations and yields steadily declined in the Embarras (from ∼10 to 6 mg S L−1) and Kaskaskia rivers (from 7 to 3.5 mg S L−1) during the sampling period, with an overall −23.1 and −12.8 kg S ha−1 yr−1 balance for the two watersheds. (continued)

      Core Ideas:
      • Riverine sulfate in agricultural watersheds responds to atmospheric deposition inputs.
      • Agricultural sulfur budgets suggest annual depletion of organic S pools.
      • Tile drains respond quickly to agricultural sulfate inputs.

      Published: May 6, 2016

    • Gregory F. McIsaac, Mark B. David and George Z. Gertner
      Illinois River Nitrate-Nitrogen Concentrations and Loads: Long-term Variation and Association with Watershed Nitrogen Inputs

      The Illinois River is a major contributor of nitrate-N to the Mississippi River and the Gulf of Mexico, where nitrate is a leading cause of summertime benthic hypoxia. Corn–soybean production on tile-drained land is a leading source of nitrate-N in this river system, in addition to municipal wastewater discharge. We calculated annual nitrate-N loads in the Illinois River at Valley City from 1976 to 2014 by linear interpolation. Although there was not a significant trend in annual loads during the entire study period, there was a significant downward trend in flow-weighted nitrate-N concentration after 1990 despite high concentrations in 2013 after the 2012 drought. (continued)

      Core Ideas:
      • Downward trend in annual flow-weighted nitrate-N concentrations since 1990.
      • Nitrate-N concentrations correlated with residual agricultural N during the previous 6 yr.
      • Nitrate-N concentrations correlated with current year Chicago wastewater discharge.
      • Nitrate-N load highly variable due to variation in precipitation and water discharge.
      • Average nitrate-N load during 2010–2014 was 10% less than the 1980–1996 baseline period.

      Published: May 6, 2016

    • X. C. (John) Zhang, B. L. Liu, B. Liu and G. H. Zhang
      Quantifying Sediment Provenance Using Multiple Composite Fingerprints in a Small Watershed in Oklahoma

      Quantitative information on sediment provenance is needed for improved calibration and validation of process-based soil erosion models. However, sediment source data are often limited due to difficulties in directly measuring source contributions at a watershed scale. Our objectives in this study were to estimate sediment source contributions in a 15-km2 watershed using analytical solutions to a three end-member mixing model using multiple composite fingerprints and to compare the results with those estimated with a single radionuclide, 137Cs. Surface soil samples were collected from 23 croplands, 19 rangelands, and 26 gully banks in the watershed, and 31 geochemical elements were analyzed for each sample. (continued)

      Core Ideas:
      • Sediment source contributions were estimated using multiple composite fingerprints.
      • Contributions from analytical solutions were compared with estimates using 137Cs.
      • Source contributions varied substantially among different composite fingerprints.
      • Multiple fingerprints greatly improved accuracy/certainty to identify sediment provenance.

      Published: April 29, 2016


    • Jos J. T. I. Boesten
      Effect of Harsh or Mild Extraction of Soil on Pesticide Leaching to Groundwater

      Assessment of leaching to groundwater is an important aspect of pesticide risk assessment. The first leaching tier usually consists of simulations with leaching scenarios based on pesticide–soil properties derived from laboratory studies. Because the extractability of pesticide residues in such studies decreases with time, the harshness of the extraction method influences these pesticide–soil properties. This study investigates the effect of using a mild or harsh extraction method on simulated leaching to groundwater with consideration of substances with a range of half-lives and organic matter sorption coefficient values for selected leaching scenarios. (continued)

      Core Ideas:
      • First model for the effect of harsh or mild extraction on pesticide behavior in soil.
      • A model based on a Dutch study produced acceptable simulation of Canadian field data.
      • The effect of harsh or mild extraction on pesticide leaching is comparatively small.
      • Mild extraction generates faster apparent degradation but less aged sorption.

      Published: May 6, 2016


    • Adeline Bougouin, April Leytem, Jan Dijkstra, Robert S. Dungan and Ermias Kebreab
      Nutritional and Environmental Effects on Ammonia Emissions from Dairy Cattle Housing: A Meta-Analysis

      Nitrogen excreted in dairy manure can be potentially transformed and emitted as NH3, which can create livestock and human respiratory problems and be an indirect source of N2O. The objectives of this study were to: (i) investigate environmental factors influencing NH3 emissions from dairy housing; and (ii) identify key explanatory variables in the NH3 emissions prediction from dairy housing using a meta-analytical approach. Data from 25 studies were used for the preliminary analysis, and data from 10 studies reporting 87 treatment means were used for the meta-analysis. Season and flooring type significantly affected NH3 emissions. (continued)

      Core Ideas:
      • Season and flooring type significantly affected NH3 emission rates.
      • Open lots had the highest emissions in this study but the lowest by USEPA.
      • Crude protein and dry matter intake had positive impacts on NH3 emissions.
      • Milk yield had negative impacts on NH3 emissions.

      Published: May 6, 2016


    • Giorgio Provolo, Alberto Finzi, Francesca Perazzolo, Gabriele Mattachini and Elisabetta Riva
      Effect of a Biological Additive on Nitrogen Losses from Pig Slurry during Storage

      Additives applied to animal manure slurries can affect the chemical composition and the biological processes of slurries during storage, with possible improvement of their management and reduction of environmental problems. Some new formulations are marketed claiming a nitrogen (N) removal effect due to denitrification, with the consequence of a reduced N content in the manure after storage. This study evaluated the effects of one of these commercial additives (BACTYcomplex) on slurry characteristics and N losses at a commercial piggery. The additive was applied to four different sectors of the piggery, each with an independent under-floor slurry pit; four other sectors served as controls without treatment. (continued)

      Core Ideas:
      • A new biological additive with denitrification enhancement capability was tested.
      • The additive increased the total solids reduction during 6 mo storage of the slurry.
      • The total and ammonia-N losses were not affected by the additive.
      • The additive promoted stabilization of slurry but did not reduce N content.

      Published: April 29, 2016

    • Geethani Amarawansha, Darshani Kumaragamage, Don Flaten, Francis Zvomuya and Mario Tenuta
      Predicting Phosphorus Release from Anaerobic, Alkaline, Flooded Soils

      Anaerobic conditions induced by prolonged flooding often lead to an enhanced release of phosphorus (P) to floodwater; however, this effect is not consistent across soils. This study aimed to develop an index to predict P release potential from alkaline soils under simulated flooded conditions. Twelve unamended or manure-amended surface soils from Manitoba were analyzed for basic soil properties, Olsen P (Ols-P), Mehlich-3 extractable total P (M3PICP), Mehlich-3 extractable molybdate-reactive P (M3PMRP), water extractable P (WEP), soil P fractions, single-point P sorption capacity (P150), and Mehlich-3 extractable Ca (M3Ca), and Mg (M3Mg). Degree of P saturation (DPS) was calculated using Ols-P, M3PICP or M3PMRP as the intensity factor, and an estimated adsorption maximum based on either P150 or M3Ca + M3Mg as the capacity factor. (continued)

      Core Ideas:
      • Phosphorus release from flooded soils to overlying water depended on soil properties.
      • Relative increase in floodwater DRP concentration could be predicted using the model.
      • Clay percentage and the degree of P saturation influenced P release from flooded soils.

      Published: April 29, 2016

    • Dustin P. Meador, Paul R. Fisher, Charles L. Guy, Philip F. Harmon, Natalia A. Peres and Max Teplitski
      Use of Dehydrated Agar to Estimate Microbial Water Quality for Horticulture Irrigation

      Petrifilms are dehydrated agar culture plates that have been used to quantify colony forming units (CFU) mL−1 of either aerobic bacteria (Petrifilm-AC) or fungus (Petrifilm-YM), depending on substrate composition. Microbes in irrigation systems can indicate biofilm risk and potential clogging of irrigation emitters. The research objective was to compare counts on Petrifilms versus traditional, hydrated-agar plates using samples collected from recirculated irrigation waters and cultures of isolated known species. The estimated count (in CFU mL−1) from a recirculated irrigation sample after 7 d of incubation on Petrifilm-YM was only 5.5% of the count quantified using sabouraud dextrose agar (SDA) with chloramphenicol after 14 d. (continued)

      Core Ideas:
      • Dehydrated agar culture plates (Petrifilms) were evaluated for bacteria and oomycetes.
      • Colony counts were quantified in irrigation water and single species cultures.
      • Petrifilm plates did not successfully culture oomycetes.
      • However, the Petrifilm was an effective method to quantify density of bacteria.
      • Petrifilms provide an easy on-farm tool to monitor irrigation water quality.

      Published: April 8, 2016


    • C. D. Barry and R. H. Foy
      Assessing the Success of Regional Measures for Lowering Agricultural Nutrient Pollution in Headwater Streams

      Lowland waters in Northern Ireland experience elevated agricultural phosphorus (P) inputs, and in response a variety of control measures targeting farm nutrient management have been implemented. Their efficacy in lowering nitrogen (N) and P exports and improving water quality is examined in 40 headwater streams from 1990 to 2009, and to 2014 for 24 of these. Over this period manure production in the study catchments declined by 7%, but regional chemical fertilizer inputs declined by 37% for N and 79% for P, and the regional nutrient surplus was lowered by 18% for N and 49% for P. Diminished pollution by organic wastes meant that 85% of streams exhibited chemistry suitable for salmonids in 2009 compared to 40% in 1990. (continued)

      Core Ideas:
      • Amelioration of point source and diffuse agricultural pollution over 20 years.
      • Reductions to diffuse N export more rapid and pronounced than for P.
      • Nutrient versus land use intensity correlations stronger after pollution amelioration.

      Published: May 6, 2016

    • P. D. K. D. Jayarathne, D. Kumaragamage, S. Indraratne, D. Flaten and D. Goltz
      Phosphorus Release to Floodwater from Calcareous Surface Soils and Their Corresponding Subsurface Soils under Anaerobic Conditions

      Enhanced phosphorus (P) release from soils to overlying water under flooded, anaerobic conditions has been well documented for noncalcareous and surface soils, but little information is available for calcareous and subsurface soils. We compared the magnitude of P released from 12 calcareous surface soils and corresponding subsurface soils to overlying water under flooded, anaerobic conditions and examined the reasons for the differences. Surface (0–15 cm) and subsurface (15–30 cm) soils were packed into vessels and flooded for 8 wk. Soil redox potential and concentrations of dissolved reactive phosphorus (DRP) and total dissolved Ca, Mg, Fe, and Mn in floodwater and pore water were measured weekly. (continued)

      Core Ideas:
      • Phosphorus released to floodwater was greater from calcareous surface soils than subsurface soils.
      • Floodwater P concentration significantly increased in >80% of surface soils with time of flooding.
      • Only 40% of subsurface soils showed a significant increase in floodwater P concentrations with flooding.
      • Phosphorus released to floodwater was mainly governed by the initial soil P concentration in soils.
      • Changes in floodwater molar ratios suggest sorption and/or reprecipitation involving Fe and Mn.

      Published: May 6, 2016

    • Chao Wang, Kung-Sik Chan and Keith E. Schilling
      Total Phosphorus Concentration Trends in 40 Iowa Rivers, 1999 to 2013

      Excessive phosphorus (P) in rivers is prompting states to develop strategies to reduce P concentrations and export. The goal of this study was to assess the current condition by analyzing trends in total P (TP) concentrations at 40 river monitoring sites in Iowa for the period 1998 to 2013. We used monthly river monitoring data collected by the State of Iowa at ambient sites located beyond the influence of point sources or cities. Study objectives were to assess the presence of any linear trends in the TP concentration data using a time-series method that accounted for temporal correlation in the data and discharge and to combine the trend information from individual sites into an assessment of the statewide rate of change in river TP concentrations. (continued)

      Core Ideas:
      • Phosphorus concentrations were assessed at 40 Iowa rivers.
      • Phosphorus concentrations were decreasing by 4.1% at 12 sites.
      • Across Iowa, P concentrations are declining annually by 2.6%.
      • Reductions are most likely attributable to conservation.

      Published: May 6, 2016

    • Heidi Holmroos, Jukka Horppila, Sanna Laakso, Juha Niemistö and Susanna Hietanen
      Aeration-Induced Changes in Temperature and Nitrogen Dynamics in a Dimictic Lake

      Low levels of oxygen (O2) in the hypolimnion layer of lakes are harmful to benthic animals and fish; they may also adversely affect nutrient cycles. Artificial aeration is often used in lake management to counteract these problems, but the effects of aeration on nitrogen (N) cycling are not known. We studied the effects of hypolimnetic aeration on N dynamics and temperature in a eutrophic lake by comparing continuous and pulsed aeration with a nonaerated station. Aeration decreased the accumulation of NH4+–N deep in the lake (20–33 m) by supplying O2 for nitrification, which in turn provided substrate for denitrification and promoted N removal. (continued)

      Core Ideas:
      • Continuous hypolimnetic aeration prevented NH4+ accumulation in a lake at 20–33 m depth.
      • Continuous aeration promoted denitrification by enabling nitrification.
      • Periodical aeration did not restrict temperature changes, but NH4+ was accumulated.
      • Denitrification rate decreased during aeration pauses.
      • Benthic N removal in a lake can be enhanced via hypolimnetic aeration.

      Published: April 29, 2016

    • Mats Larsbo, Maria Sandin, Nick Jarvis, Ararso Etana and Jenny Kreuger
      Surface Runoff of Pesticides from a Clay Loam Field in Sweden

      Pesticides stored at or close to the soil surface after field application can be mobilized and transported off the field when surface runoff occurs. The objective of our study was to quantify the potential pesticide losses in surface runoff from a conventionally managed agricultural field in a Swedish climate. This was achieved by measuring surface runoff volumes and concentrations in runoff of six spring-applied pesticides and autumn-applied glyphosate and its metabolite aminomethylphosphonic acid (AMPA). Measurements were performed for 3 yr both during the growing seasons and during intervening winter snowmelt periods on a clay loam field close to Uppsala. (continued)

      Core Ideas:
      • Pesticide concentrations often exceeded Swedish water quality standards.
      • All of the applied pesticides were found in samples taken during snowmelt.
      • Total pesticide losses were small due to small surface runoff volumes.
      • Temporal changes in hydraulic properties affected losses in surface runoff.

      Published: April 22, 2016

    • Luying Wang, Qingyou Liu, Kai Zheng and Heping Li
      Assessing the Influence of Calcium Fluoride on Pyrite Electrochemical Dissolution and Mine Drainage pH

      We investigated the influence of dissolved calcium fluoride, CaF2(aq), on the electrochemical dissolution of pyrite and the corresponding environmental effects on acid mine drainage (AMD). The experimental results showed that CaF2(aq) promotes pyrite electrochemical dissolution. When the CaF2(aq) concentration increased from 0 to 10 mg L–1 up to saturation, the promoting efficiency was 15.80 and 57.25%, respectively. The reason for this phenomenon is that F- and Fe2+ form FeF2, and at a higher scan potential, F and Fe3+ form the ion complex FeF63−. (continued)

      Core Ideas:
      • Results showed CaF2 could effectively promote pyrite electrochemical dissolution.
      • F– and Fe2+ form FeF2, and at a higher scan potential, F– and Fe3+ form the complex FeF63–.
      • Iron fluorine complex formation decreases charge transfer resistance at the double layer.
      • Strong penetration of F–into the double layer decreases the resistance at the cover layer.
      • AMD was significantly aggravated because CaF2 promoted the pyrite dissolution.

      Published: April 22, 2016


    • Mriganka De and Gurpal S. Toor
      Mass Balance of Water and Nitrogen in the Mounded Drainfield of a Drip-Dispersal Septic System

      Quantitative assessment of nitrogen (N) loading from septic systems is needed to protect groundwater contamination. We determined the mass balance of water and N in the mounded drainfield of a drip-dispersal septic system. Three lysimeters (152.4 cm long, 91.4 cm wide, 91.4 cm high, with 1:1 side slope) were constructed using pressure-treated wood to mimic mounded drainfields. Of total water inputs, septic tank effluent (STE) added 57% water and natural rainfall added 43% water from January 2013 to January 2014. (continued)

      Core Ideas:
      • Mass balance of water and N was determined in septic system drainfields.
      • Effluent added 57% water, and rainfall added 43% water.
      • More water leached (46%) than evapotranspiration (28%) and soil storage (26%).
      • Effluent added 99% of total N, and rainfall added only 1% of total N.
      • Gaseous N loss was higher (38%) than leaching (33%) and soil storage (23%).

      Published: May 13, 2016

    • Gurpal S. Toor and J. Thomas Sims
      Phosphorus Leaching in Soils Amended with Animal Manures Generated from Modified Diets

      New dietary modifications for dairy (reducing P content in feed) and poultry (addition of feed additives such as phytase) aim to reduce P excretion in manures. Our objective was to investigate if dietary changes were effective at reducing P leaching loss on land application of manures. We used 54 undisturbed lysimeters (30 cm diameter, 50 cm deep) collected from three typical mid-Atlantic soils. Lysimeters received 85 kg total P ha−1 from fertilizer (superphosphate), dairy manures generated from low- or high-P diets, or broiler litters generated from normal diet or reduced P- and phytase-amended diets. (continued)

      Core Ideas:
      • Dissolved unreactive P was the major form leached from the mid-Atlantic soils.
      • Existence of preferential flow pathways in soils caused greater P leaching.
      • Soil and manure characteristics controlled P leaching from soils.

      Published: April 22, 2016


    • Lidong Huang, Philip A. Moore, Peter J. A. Kleinman, Kyle R. Elkin, Mary C. Savin, Daniel H. Pote and Dwayne R. Edwards
      Reducing Phosphorus Runoff and Leaching from Poultry Litter with Alum: Twenty-Year Small Plot and Paired-Watershed Studies

      Treating poultry litter with alum has been shown to lower ammonia (NH3) emissions and phosphorus (P) runoff losses. Two long-term studies were conducted to assess the effects of alum-treated poultry litter on P availability, leaching, and runoff under pasture conditions. From 1995 to 2015, litter was applied annually in a paired watershed study comparing alum-treated and untreated litter and in a small plot study comparing 13 treatments (an unfertilized control, four rates of alum-treated litter, four rates of untreated litter, and four rates of NH4NO3). In the paired watershed study, total P loads in runoff were 231% higher from pasture receiving untreated litter (1.96 kg P ha−1) than from that receiving alum-treated litter (0.85 kg P ha−1). (continued)

      Core Ideas:
      • Two 20-yr studies were conducted on the effects of treating poultry litter with alum.
      • Phosphorus runoff from paired watersheds was 231% higher with normal litter than alum-treated litter.
      • Surface soil samples had significantly higher M3-P levels when fertilized with alum-treated litter.
      • Mehlich 3 results indicate alum additions to poultry litter reduce organic P leaching.
      • Phosphorus leaching from plots fertilized with normal litter was 266% greater than with alum-treated litter.

      Published: May 13, 2016

    • Philip A. Moore
      Development of a New Manure Amendment for Reducing Ammonia Volatilization and Phosphorus Runoff from Poultry Litter

      Treating poultry litter with alum is a best management practice that reduces phosphorus (P) runoff and ammonia (NH3) emissions. However, alum prices have increased substantially during the past decade. The goal of this research was to develop inexpensive manure amendments that are as effective as alum in reducing NH3 volatilization and P runoff. Sixteen amendments were developed using mixtures of alum mud, bauxite ore, sulfuric acid, liquid alum, and water. (continued)

      Core Ideas:
      • Alum additions to poultry litter reduce ammonia emissions and P runoff.
      • The price of alum has increased dramatically, creating a need for cheaper products.
      • New manure amendments were developed using alum mud (a byproduct), bauxite, and sulfuric acid.
      • Three of these new products reduced ammonia volatilization and WEP as well as alum.
      • These new amendments should be more cost-effective than alum because they are cheaper to produce.

      Published: May 6, 2016

    • Dandan Song, Shengkang Liang, Lele Yan, Yujun Shang and Xiuli Wang
      Solubilization of Polycyclic Aromatic Hydrocarbons by Single and Binary Mixed Rhamnolipid–Sophorolipid Biosurfactants

      Biosurfactants are promising additives for surfactant enhanced remediation (SER) technologies due to their low toxicity and high biodegradability. To develop green and efficient additives for SER, the aqueous solubility enhancements of polycyclic aromatic hydrocarbons (PAHs; naphthalene, phenanthrene, and pyrene) by rhamnolipid (RL) and sophorolipid (SL) biosurfactants were investigated in single and binary mixed systems. The solubilization capacities were quantified in terms of the solubility enhancement factor, molar solubilization ratio (MSR), and micelle-water partition coefficient (Km). Rughbin’s model was applied to evaluate the interaction parameters (β) in the mixed RL–SL micelles. (continued)

      Core Ideas:
      • Micellization behaviors of rhamnolipid–sophorolipid systems (RL–SL) were investigated.
      • Mixed RL–SL systems generally enhanced the water solubility of PAHs.
      • Mixed biosurfactant systems might be used for surfactant-enhanced PAH remediation.

      Published: April 29, 2016

    • Kenneth A. Barbarick, James A. Ippolito and Jacob P. McDaniel
      Path Analyses of Grain P, Zn, Cu, Fe, and Ni in a Biosolids-Amended Dryland Wheat Agroecosystem

      Land application of biosolids is an effective means of recycling plant nutrients and is the primary method of biosolids reuse endorsed by the USEPA. One issue concerning biosolids application is the extent of the contribution of biosolids-borne plant nutrients to the overall crop concentration and uptake or removal of these nutrients. We studied the effects of biosolids application on wheat (Triticum aestivum L.) grain P, Zn, Cu, Fe, and Ni concentrations and uptake (removal) at two dryland agroecosystem sites from 1993 to 2014. We hypothesized that biosolids would have the greatest impact on wheat grain and uptake compared with ammonium bicarbonate–diethylenetriaminepentaacetic acid (AB-DTPA)-extractable nutrient levels, soil pH, or soil organic C concentrations. (continued)

      Core Ideas:
      • Path analysis identifies nutrient source in biosolids-amended winter wheat.
      • Cumulative biosolids applications affect P, Zn, Cu, Fe, and Ni grain removal.
      • Cumulative biosolids applications did not affect P, Zn, Cu, Fe, and Ni grain concentrations.

      Published: April 8, 2016

    • Peter L. O’Brien, Thomas M. DeSutter, Francis X. M. Casey, Nathan E. Derby and Abbey F. Wick
      Implications of Using Thermal Desorption to Remediate Contaminated Agricultural Soil: Physical Characteristics and Hydraulic Processes

      Given the recent increase in crude oil production in regions with predominantly agricultural economies, the determination of methods that remediate oil contamination and allow for the land to return to crop production is increasingly relevant. Ex situ thermal desorption (TD) is a technique used to remediate crude oil pollution that allows for reuse of treated soil, but the properties of that treated soil are unknown. The objectives of this research were to characterize TD-treated soil and to describe implications in using TD to remediate agricultural soil. Native, noncontaminated topsoil and subsoil adjacent to an active remediation site were separately subjected to TD treatment at 350°C. (continued)

      Core Ideas:
      • Soil from a crude oil spill site was remediated using thermal desorption.
      • Thermal desorption treatment reduced SOC, SSA, and aggregation.
      • Changes to physical properties caused increased Ks and decreased water retention.
      • Soils subjected to TD may be less effective in crop production than native soil.
      • Adding organic amendments to TD-treated soil may ameliorate some effects of TD.

      Published: April 8, 2016

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