bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rye Cover Crop and Nitrogen Fertilization Effects on Nitrate Leaching in Inbred Maize Fields
Authors: Rasse Daniel P. , Ritchie Joe T. , Peterson W. Richard , Wei Jun , Smucker Alvin J. M. 
Published: July 2010

AbstractNitrate leaching from maize (Zea mays L.) fields fertilized in excess of plant requirements continue to threaten water quality even though many agronomists have recommended reducing N fertilization rates to contain this environmental risk. Inbred maize has lower N uptake than conventional hybrid maize; therefore, inbred maize production exposes soils to even greater ground water pollution risks by nitrates. A 3‐yr field experiment was conducted on sandy loam soils in southwestern Michigan to investigate the combined effects of N fertilization rates and rye (Secale cereale L.) cover crops on NO3 leaching in inbred maize fields. Inbred maize was fertilized at 0, 101, and 202 kg N ha−1. Annual NO3 leaching losses were 7 kg N ha−1 higher in fields fertilized at 101 kg N ha−1 than in nonfertilized controls. Annual NO3 leaching losses to ground water between May 1995 and April 1998 from lysimeters fertilized at 202 kg N ha−1 averaged 88 kg NO3‐N ha−1. Rye interseeded with inbred maize fertilized at 202 kg N ha−1 sequestered from 46 to 56 kg ha−1 of excess fertilizer N. Rye scavenged little residual fertilizer N in plots fertilized at 101 kg N ha−1. Well established rye cover crops in 1996 reduced NO3 leaching by as much as 65 kg N ha−1 when the previous crop was fertilized with 202 kg N ha−1. Therefore, rye cover crops sequestered substantial amounts of soil NO3 in heavily fertilized inbred maize fields.
Bentonite and Humic Acid as Modifying Agents in Controlled Release Formulations of Diuron and Atrazine
Authors: Fernández‐Pérez M. , González‐Pradas E. , Villafranca‐Sánchez M. , Flores‐Céspedes F. , Ureña‐Amate M. D. 
Published: July 2010

AbstractThe herbicides diuron [3‐(3,4‐dichlorophenyl)‐1,1‐dimethylurea] and atrazine [6‐chloro‐N2‐ethyl‐N4‐isopropyl‐1,3,5‐triazine‐2,4‐diamine] were incorporated in alginate‐based granules to obtain controlled release (CR) properties. The basic formulation [sodium alginate (14.0 g kg−1)‐herbicide(6.0 g kg−1)‐water] was modified by addition of sorbents. The effect on (Huron and atrazine release rate, caused by incorporation of natural bentonite and humic acid in the alginate formulation, was studied by immersion of the granules in water under static conditions. The release of the active ingredient from alginate‐based CR granules in water was affected by the addition of natural bentonite, and to a greater extent, by the addition of the humic acid. The water uptake, permeability, and the time taken for 50% of active ingredient to be released into water, T50, were calculated for the comparison of the preparations. Addition of both bentonite and humic acid samples to the basic alginate‐based formulation produced the higher T50 values (43.11 and 50.49 d for diuron and atrazine formulations, respectively), indicating a slower release of herbicide. Based on parameters of an empirical equation used to fit the herbicide release data, it appears that the release of diuron and atrazine from the various formulations into water is controlled by a diffusion mechanism. Sorption capacity of the sorbent and the permeability of the formulations (ranging from 3.77 to 20.83 mg d−1 mm−1) were the most influential factors affecting herbicide release.
Relationship of Soil Organic Matter Characteristics to Organic Contaminant Sequestration and Bioavailability
Authors: Lueking Angela D. , Huang Weilin , Soderstrom‐Schwarz Sara , Kim Minsun , Weber Walter J. 
Published: July 2010

AbstractSorption and desorption equilibria of phenanthrene with respect to three different types of geosorbents were measured, as were the rates of desorption and biological mineralization of this representative hydrophobic organic contaminant. The chemical nature of the organic matter associated with each geosorbent was characterized using solid state 13C‐NMR spectrometry. The results of these studies reveal that both the desorption behavior and the microbial bioavailability of the sorbed contaminant are influenced by the physicochemical character of the organic matter. The more reduced and condensed the organic matter, the greater the extent of sorption‐desorption hysteresis, the slower the desorption rate, and the less readily bioavailable the sorbed contaminant. These observations are consistent with projections predicated on a dual reactive domain model introduced earlier to describe the sorptive reactivities of different types of soil/sediment organic matter with hydrophobic organic contaminants.
Nitrogen Mineralization of Lime‐Stabilized Fishwaste in Acid Soils and its Effect on Plant Growth
Authors: Kuo S. , Bristow P. R. , Jellum E. J. , Okiro M. 
Published: July 2010

AbstractFishwaste is often disposed of in landfills or the ocean, adversely affecting water quality. With its high protein content, fishwaste could instead be used as a N source for crop production. The viability of a lime‐stabilized fishwaste (LSF) product as a N source was tested by determining its effects on net N mineralization, growth of bacteria, and the growth of a variety of plant species in two acidic soils. Net N mineralization and viable bacteria number were significantly increased (P < 0.001) by the addition of LSF. At the highest rate of 30 g LSF kg−1 soil, high NH4‐N accumulation was extended to several weeks and a longer lag period before bacteria growth occurred. At such a high rate, nitrification, but not the activities of proteolytic enzymes, was severely impaired. The considerably high inactivation rate for the bacteria following the exhaustion of the available energy in the protein in the Sultan soil [half life = 4.5 ± 0.5 d (SD)] may explain why the Sultan soil had a comparatively higher net N mineralization rate than the Puyallup soil [half life = 14.7 ± 3.5 d (SD)]. At 6 g LSF kg−1 soil in a greenhouse trial, the N availability to a variety of crops was generally increased. Unless a soil is extremely acidic, using high rates of LSF can lead to undesirable soil conditions (high pH and NH4‐N accumulation) that interfere with plant growth.
Characterization and Extractability of Copper, Manganese, and Zinc in Swine Manure Composts
Authors: Hsu Jenn‐Hung , Lo Shang‐Lien 
Published: July 2010

AbstractSwine (Sus domesticus) manure was comprehensively characterized with respect to Cu, Mn, and Zn in feed additives. This research was conducted to study the leachability and identify factors influencing the leachability of these elements from separated swine manure (SSM) composts to assess its environmental hazard. Several chemical properties were determined to assess the degree of maturity of eight SSM composts. A series of extraction schemes were used to determine base‐extractable metals and their distribution on humic substance fractions (humic acid, HA; fulvic acid, FA; and nonhumic fraction, NHF), chemical fractionation, synthetic acid rainwater (SAR) solubility, and extractability at various pH levels of metals in composts. We evaluated the influence of dissolved organic carbon from compost on the extractability of these metals. The SSM composts were enriched with Cu (154–1380 mg kg−1), Mn (239–976 mg kg−1), and Zn (372–2840 mg kg−1). The SAR and neutral‐pH extractable fractions of Cu, Mn, Zn, and organic C were generally low (<10% of their total content). Copper leachability in Sample F2 compost, however, was high (20%), resulting from immaturity and associated substantial dissolution of organic C (18%). High extractability (86%) of Cu from humic substances (HS) extraction and at high pH levels (>8) resulted from dissolution of organic matter. Conversely, the extractability of Mn and Zn at alkaline pH levels was low. The major portions of Cu, Mn, and Zn were found in the organic, oxide, and carbonate fractions, respectively, regardless of their content in these composts. The results of this study show that Cu in SSM compost is primarily bound to organics.
Removal of Perchlorate in Ground Water with a Flow‐Through Bioreactor
Authors: Giblin Tara , Herman David , Deshusses Marc A. , Frankenberger William T. 
Published: July 2010

AbstractThe bacterium, perc1ace, has been shown to reduce perchlorate to less than the detection limit of 0.004 mg L−1 when grown on acetate under anaerobic conditions. In batch studies, the presence of nitrate does not significantly hinder the reduction of perchlorate. The ability of perclace to remove nitrate and perchlorate from ground water in a flow‐through system is described in this study. Celite‐packed columns of 300 ml were used to demonstrate the removal of perchlorate from ground water. At a flow rate of 1 ml min−1, perchlorate was removed from 0.738 mg L−1 to less than detectable levels and when the flow rate was 2 ml min−1 92 to 95% of the perchlorate was removed. Analysis of bacterial biomass at the completion of the study revealed that most of the bacterial growth was concentrated in the inlet area of the column. A circulating pump was added, with the idea that passing the ground water multiple times through the bacterially active zone might increase the efficiency of the column. In this experiment, perchlorate in ground water was reduced from 0.550 mg L−1 to nondetectable levels at a flow rate of 1 ml min−1. When the flow rate was increased to 2 ml min−1, 98% of perchlorate was removed and when the flow rate was 3 ml min −1 95% of perchlorate was removed. Rapid removal of perchlorate by perc1ace immobilized in a bioreactor may provide an efficient, cost‐effective technology for ground water remediation.
Phenanthrene‐Degrader Community Dynamics in Rhizosphere Soil from a Common Annual Grass
Authors: Miya Ryan K. , Firestone Mary K. 
Published: July 2010

AbstractEnhanced rates of phenanthrene biodegradation were observed in rhizosphere soils (17.2 and 15.5 mg/kg/d for initial and re‐spiked additions, respectively) planted with slender oat (A vena barbata Pott ex Link) compared with unplanted bulk soil controls (12.4 and 10.7 mg/kg/d). Soil microbial populations were characterized using a modified most probable number (MPN) method to determine quantitative shifts in heterotrophic and phenanthrene degrader communities while principal component analysis (PCA) of fatty acid methyl ester (FAME) data from isolated phenanthrene degraders was used to identify qualitative differences and degrader community diversity. The average heterotrophic bacterial population over time was about three times larger in rhizosphere soil than in bulk soil while phenanthrene degrading populations increased by as much as an order of magnitude between 24 and 28 days after planting (DAP). Thus, phenanthrene degraders were selectively enriched in rhizosphere soil compared with bulk soil. The greatest selection for degraders occurred during the later stages of plant development from 24 to 32 DAP. A PCA plot of the FAME data from phenanthrene degrader isolates indicated that the rhizosphere degraders were less diverse than bulk soil degraders. These results give us some insight into the mechanisms responsible for enhanced biodegradation and selective degrader enrichment in rhizosphere soils.
Organic Matter Transformations During the Weathering Process of Spent Mushroom Substrate
Authors: Chefetz Benny , van Heemst Jasper D. H. , Chen Yona , Romaine C. Peter , Chorover Jon , Rosario Rex , Mingxin Guo , Hatcher Patrick G. 
Published: July 2010

AbstractThe weathering process of spent mushroom substrate (SMS) was studied to better understand the chemical properties and transformations of organic matter (OM) during the process. The SMS was piled (20 m by 6 m row of 1.5 m height) in an open field and weathered during 15 mo. Chemical properties of the OM collected from the top and bottom parts of the weathering pile were studied using 13C‐nuclear magnetic resonance (NMR), tetramethylammonium hydroxide (TMAH) thermochemolysis‐gas chromatograph/mass spectrometry (GC/MS), and pyrolysis‐gas chromatograph/mass spectrometry (Py‐GC/MS). The 13C‐NMR data suggested that weathered SMS from the top part of the pile degraded rapidly: the relative level of polysaccharides decreased by 33% while the level of aromatic C increased by 21% during the process. The TMAH thermochemolysis chromatogram exhibited peaks of methylated derivatives of phenyl, guaiacyl and syringyl structures as well as some fatty acid methyl esters. Lignin‐derived products from TMAH thermochemolysis indicate that preferential degradation of syringyl units and oxidation of Cα‐Cβ bonds occurred in the SMS from the top part of the pile. In contrast, no major changes in lignin‐derived structures were observed in the weathered SMS from the bottom part of the pile. The 13C‐NMR, Py‐GC/MS and TMAH thermochemolysis‐GC/MS analyses indicated that the SMS decomposed rapidly at the top part of the weathering pile, whereas decomposition at the bottom of the pile was significantly slower, probably due to lack of oxygen. These analyses were shown to be useful techniques for the characterization of degradation processes in SMS. Therefore, their application to studies on OM transformation and humification processes is highly recommended.
Effect of Soil Conditions on the Degradation of Cloransulam‐Methyl
Authors: Cupples Alison M. , Sims Gerald K. , Hultgren Ryan P. , Hart Steven E. 
Published: July 2010

AbstractHerbicide efficacy and environmental fate are often controlled by soil conditions. Aerobic soil laboratory studies were undertaken to determine the degradation of the herbicide cloransulam‐methyl [N‐(2‐carbomethoxy‐6‐chloro‐phenyl)‐5‐ethoxy‐7‐fluoro[1,2,4]triazolo [1,5‐c]pyrimidine‐2‐sulfonamide] for a range of soil factors. Treatments included soil temperature (5, 15, 25, 40, and 50°C), moisture (20, 40, and 60% water filled pore space), and soil type. The soils under study were a Drummer silty clay loam (fine‐silty, mixed, super‐active, mesic Typic Endoaquolls) and a Cisne silt loam (fine, smectitic, mesic Vertic Albaqualfs). Variability in molecular degradation was investigated using two radiolabeled forms ([Phenyl‐UL‐14C] and [Pyrimidine‐7,9‐14C]). Dissipation of parent compound in soil solution and sorbed phases, formation of radiolabeled metabolites, 14C mineralization, total microbial respiration, and bound residue formation were measured for up to 120 d. Dissipation of parent and formation of bound residues in Drummer soil increased with greater temperatures. The influence of temperature on 14C mineralization, however, was dependent on position of radiolabel, suggesting that distinct groups of microorganisms degrade different parts of the molecule at higher temperatures. Only 14C mineralization was influenced by moisture, with response depending on soil type. Increasing moisture resulted in more 14C mineralization in Drummer, but not Cisne soil, which was attributed to increased microbial access to pesticide at greater moisture contents in Drummer soil. Reduced availability, suggested by greater sorption in Drummer soil, may explain persistence of parent in this soil. Bound residues were more extensive and exhibited greater dependence on biological activity in Cisne soil, owing to enhanced dissipation of parent compound in this soil.
Assessment of the Condition of Agricultural Lands in Six Mid‐Atlantic States
Authors: Hellkamp Anne S. , Bay Jeff M. , Campbell C. Lee , Easterling Karen N. , Fiscus Daniel A. , Hess George R. , McQuaid Betty F. , Munster Michael J. , Olson Gail L. , Peck Steven L. , Shafer Steven R. , Sidik Kurex , Tooley Mark B. 
Published: July 2010

AbstractIndicators of the condition and sustainability of agricultural lands covering 5.5 million ha in six mid‐Atlantic states were measured in 1994 and 1995. The primary objective was to collect baseline information against which future data from the region can be compared. Soil samples and questionnaire data were collected from a random sample of 293 sites. Indicators addressed productivity, management at the agroecosystem scale, and management for the landscape scale on annual crop land. Crop yields were almost 30% higher than those of the 1980s, with a mean observed to expected yield index of 1.27. The mean soil quality index showed moderate quality for supporting plant growth. Non‐tilled sites, which were mostly hay, had greater microbial biomass than tilled sites. Just over half of the annual crop land was covered by rotation plans; hay fields accounted for most of the land where one crop was grown continuously. Hay showed a lower use of applied nitrogen than seed crops. Integrated pest management was practiced on less than 20% of annual crop land. Twenty‐seven different annual crops were grown in the region, with hay (all types) the dominant crop. Less than 20% of the land where pesticides were applied had high to moderately high potential for pesticides leaching into ground water. This information provides a baseline for long‐term monitoring of agricultural lands in the region.
17 β‐Estradiol as an Indicator of Animal Waste Contamination in Mantled Karst Aquifers
Authors: Peterson E. W. , Davis R. K. , Orndorff H. A. 
Published: July 2010

AbstractThe poultry and cattle industries comprise a large segment of the agricultural economy in the mantled karst area of northwest Arkansas. The associated risks of nutrient and bacterial contamination to karst aquifers by poultry litter have been well documented. However, only recently have the risks associated with hormones, specifically 17 β‐estradiol (E2), been addressed. During a winter recharge event, five springs in northwest Arkansas were sampled and the waters were analyzed for E2, fecal coliform, and Escherichia coli. Analyses of the waters from five springs representing three different water‐bearing formations revealed that E2 is present in the waters. Concentrations of E2 ranged from 6 to 66 ng/L. The observed E2 concentration trends imitated the changes in stage over the recharge event. The E2 concentration trends were similar to the concentration trends of both fecal coliform and E. coli at all five springs, indicating that the three components move in the mantled karst system similarly.
Regional‐Scale Leaching Assessments for Tenerife: Effect of Data Uncertainties
Authors: Diaz‐Diaz Ricardo , Loague Keith 
Published: July 2010

AbstractThis paper reports assessments of nonpoint‐source (NPS) ground water vulnerability due to pesticide leaching for the Canary Island of Tenerife. Index‐based estimates of contamination potential were made for the pesticides Carbofuran and Ethoprophos using the attenuation and retardation factors (AF and RF). The major objective this effort was to characterize the data‐related uncertainties, using first‐order uncertainty analysis, that are associated with the new pesticide leaching estimates for Tenerife. The crop, recharge, and soils data for Tenerife were overlaid in this regional‐scale study using a geographic information system approach. The strategy was to identify the effect of supplemental information in reducing uncertainties in the island‐wide vulnerability estimates. Data improvements were estimated as reductions in the AF and RF input parameter uncertainties. The greatest improvements in the Tenerife vulnerability estimates were found for reductions in the chemical data uncertainties. The new vulnerability assessments for Tenerife will be useful for future agrochemical regulation decisions and for targeting critical areas that may require remediation.
Transport of Mercury from a Cultivated Field during Snowmelt
Authors: Balogh S. J. , Meyer M. L. , Hansen N. C. , Moncrief J. F. , Gupta S. C. 
Published: July 2010

AbstractTotal mercury (THg) was determined in snow, overland snowmelt runoff, and soil from a small cultivated catchment. Total mercury concentrations in snow were low [mean concentration = 1.04 ng/L (liquid basis); n = 9; CV = 23%], while THg concentrations in snowmelt runoff were much higher, ranging from 16 to 22 ng/L. The THg concentration of suspended particulates in the runoff (52 µg/kg) was much higher than observed surface soil THg concentrations (mean concentration = 26 µg/kg; n = 6; CV = 16%). Particle size analysis showed the clay content of the runoff sediment was approximately twice that of the bulk surficial soil. These results suggest that snowmelt runoff preferentially mobilizes very fine soil partides (clays) that have a THg concentration that is greater than that of the bulk surficial soil. The total mass of THg in the snowpack prior to snowmelt was 1.26 mg, and that delivered from the catchment during the snowmelt event was 0.36 mg. This suggests there was a net accumulation of THg in the catchment soil over the winter. Soil erosion and transport are the primary mechanisms that control THg delivery from this catchment during snowmelt events.
The Near‐Stream Zone is a Source of Nitrogen in a Swedish Forested Catchment
Authors: Fölster Jens 
Published: July 2010

AbstractMost Swedish forests efficiently retain N from deposition and runoff N can be expected to originate from the near‐stream zone. Nitrogen leaching from this region is low, but still may be of ecological relevance (e.g., in oligotrophic lakes). In the present study the function of the near‐stream zone with respect to N chemistry in stream water of a small pristine catchment in central‐south Sweden was investigated. The study included ground water, soil water, and stream water sampling. The aim was to explain the variation in N species in stream water with hydrological flow paths and the spatial and temporal variation in N in ground water and soil water. Nitrate and ammonium concentrations were negligible in ground water and soil water at most locations. When nitrate occurred, it was usually at concentrations below 100 µg N L−1 and related to higher pH and aerobic conditions. Ammonium was detected in anaerobic locations at stable concentrations up to 200 µg N L−1. The near‐stream zone was the main source of organic N entering the stream where the median concentration was 240 µg L−1. Nitrate occurred only occasionally in stream water at concentrations around 100 µg N L−1 and then probably originated from near‐stream pre‐event water. The only significant ammonium concentrations were detected during a spring flow episode and there were indications of flushing of organic matter of microbial origin. The importance of within‐catchment variation for understanding leaching processes in forested catchments is discussed.
Nonsingular Sorption of Organic Compounds in Soil: The Role of Slow Kinetics
Authors: Altfelder Sven , Streck Thilo , Richter Jörg 
Published: July 2010

AbstractNonsingular sorption‐desorption behavior of organic compounds has been frequently observed, but it remained unexplained in many cases. In this study we investigate the role slow kinetics may play in nonsingular sorption. Sorption‐desorption experiments were carried out with the herbicide chortoluron (3‐(3‐chloro‐p‐tolyl)‐1,1‐dimethylurea) and two soils—a silt loam and a loamy sand—using three different batch techniques. The first technique is the classic decantrefill method where part of the supernatant is replaced with solute‐free solution. The second technique is similar;, however, part of the supernatant is replaced with solute containing solution instead. In the third technique desorption is induced by successive dilution of the supernatant with time. Nonsingular sorption of chlortoluron was observed independent of the method. We fitted a kinetic two‐stage model to the data of the first technique to estimate sorption rate parameters. With this set of parameters, the model predicted the data measured with the second and third technique well. The agreement indicates that nonsingularity phenomena observed by means of the different techniques may be explained by slow sorption kinetics. The ability of the model to describe nonsingular sorption‐desorption data was further tested on data sets taken from the literature where nonsingularity remained unexplained or was explained by other causes different from slow kinetics. All phenomena observed in the different studies could readily be explained by the two‐stage model.