bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dairy Manure Management: An Application of Probabilistic Risk Assessment
Authors: Johnson Andrew , Thurow Amy Purvis , Vietor Donald 
Published: July 2010

AbstractContemporary agricultural enterprises are having difficulty dealing with changing public perceptions about the environmental consequences of current management practices. This study was initiated to investigate the role Probabilistic Risk Assessment (PRA) could play in managing risks and communicating risk information to regulators and the public. The utility of PRA for dairy manure and wastewater management systems was evaluated on three Texas dairies beginning in spring 1992. Information collected from dairymen, along with computerized risk analysis, was used to develop risk estimates for various environmental hazards associated with the dairies. Qualitative and quantitative analysis of individual probability estimates allowed evaluation of the risks posed by various potential nutrient loss pathways. Integration of these probability estimates with simple cost‐effectiveness evaluations provided a risk/cost‐effectiveness value used in comparing alternative waste management technologies. Results indicate PRA, wedded with cost‐effectiveness analysis, may provide a new and effective way for the agricultural community to evaluate, manage, and communicate risk information.
Movement of Simazine in Runoff Water from Citrus Orchard Row Middles as Affected by Mechanical Incorporation
Authors: Troiano J. , Garretson C. 
Published: July 2010

AbstractIn California, preemergence herbicide residues have been measured in runoff water from citrus orchards that resulted from winter rainfall. This study measured the effect of rainfall on the redistribution of herbicides within a citrus orchard and the effect that shallow mechanical incorporation had on residue movement. Simulated rainfall treatments were applied to plots within a citrus orchard where simazine was applied only to row middles. Simazine (2‐chloro‐4, 6‐bis [ethylamino]‐s‐triazine) movement in runoff water was compared between middles that were either undisturbed, the normal orchard practice, or subject to shallow mechanical incorporation. In undisturbed middles, simazine concentration in runoff water collected from the first of two simulated rain events averaged 0.87 mg L−1; simazine concentration in runoff water from a second event applied 7 d later averaged 0.40 mg L−1. Shallow mechanical incorporation of row middles decreased runoff water volume from the first simulated rain event by approximately 50% with simazine concentration decreased to 0.14 mg L−1; runoff water volume was unaffected at the second rainfall event but simazine concentration remained low at 0.07 mg L−1. Total simazine mass removed from both events, which also accounts for mass recovered in furrow soil, was estimated at 13.1% of the amount applied to row middles in undisturbed plots compared to only 2.1% in mechanically disturbed middles. We conclude that ambient rainfall is unreliable for incorporation of preemergence herbicides into orchard soil with low infiltration, and that shallow mechanical incorporation should be tested under commercial citrus growing conditions.
Modeling Pesticide Transport in an Irrigated Field with Variable Water Application and Hydraulic Conductivity
Authors: Ellerbroek D. A. , Durnford D. S. , Loftis J. C. 
Published: July 2010

AbstractThe impact of spatially varying hydraulic properties on chemical transport in the unsaturated zone has been extensively studied. However, few studies have investigated the impact of variable water application on chemical transport. This paper uses field data and a modeling study to evaluate the relative importance of intrinsic and extrinsic sources of variability on pesticide transport through a field soil. Saturated hydraulic conductivity represented the source of intrinsic variability and water application was studied as a source of extrinsic variability. A conceptual model of water flow and solute transport was developed based on results from soil cores, shallow groundwater samples, and dye studies. One important result of the field study was the detection of low levels of the applied pesticide metolachlor ([2‐chloro‐N‐(2‐ethyl‐6‐methylphenyl)‐N‐(2‐methoxy‐1‐methyethyl) acetamide]) in groundwater samples collected at 2.6 m below ground surface after an average application of only 0.097 m of water. Dye studies indicated gravity‐driven fingered flow occurred in the subsoil, which may explain the early detection of pesticide in the shallow groundwater. Monte Carlo simulations revealed that the variability of water application had a greater impact on pesticide transport than the variability of saturated hydraulic conductivity at this site. Therefore, improving sprinkler uniformity represents an important best management practice (BMP) for reducing groundwater contamination by agricultural chemicals under the conditions studied.
Preferential Transport of a Bromide Tracer Applied in a Pulse of Ponded Water
Authors: Timlin D. J. , Ahuja L. R. , Heathman G. C. 
Published: July 2010

AbstractThe objective of this study was to quantify relations between preferential transport of a solute and initial water content, infiltration rate, and porosity in a field soil where preferential transport was mainly due to soil heterogeneity. We measured the horizontal and vertical distribution of a tracer chemical applied with ponded water to study the flow paths of the tracer. The soil at the site is a Bosville fine sandy loam (fine‐mixed, thermic Albaquic Paleudalfs). Strontium bromide (SrBr2) tracer was applied with a dye (methylene blue) in a 100 or 50‐mm pulse of water to soil within eight double ring infiltrometers. After 48 h the soil in each infiltrometer was sampled to 0.7 m. Twelve horizontally oriented, continuous soil samples 0.1 m long were collected at each depth. There were very few dye stains of root hairs, root channels, and pores to a depth of about 50 to 80 mm. Recoveries of Br to 0.5 m ranged from 36 to 56% applied. Bromide recovery was negatively correlated with initial water content and positively with total porosity. Below 0.35 m in depth resident solute concentration at a sampling position was positively correlated with concentration in the layer above indicating preferential vertical flow paths. It appeared that a large fraction of solute transport was through the highly porous areas of the cross‐section of soil bounded by the infiltrometer ring. The preferential transport of Br in this study was influenced largely by the properties of the clay layer at 0.35 m that had the lowest conductivity and lowest porosity in the profile and appeared to have cracks filled with sand.
Protein Content in Dairy Cattle Diets Affects Ammonia Losses and Fertilizer Nitrogen Value
Authors: Paul J. W. , Dinn N. E. , Kannangara T. , Fisher L. J. 
Published: July 2010

AbstractAltering feeding strategies for dairy cattle (Bos taurus) may reduce manure N excretion and NH3 emission from the manure. We determined the effect of dietary formulation on NH3 emission immediately following manure excretion and the availability of manure N for plant growth. Manure (urine and feces) was collected from dairy cattle fed diets containing crude protein levels of 16.4% (T1High), 15.3% (T1Med), and 12.3% (T1Low) in trial 1, and 18.3% (T2High), 16.7% (T2Med), and 15.3% (T2Low) in trial 2. Ammonia emission was measured in the laboratory for up to 48 h. Emissions during the first 24 h following manure excretion were 38 and 23% of the total manure N from Diets T1High and T1Low, and 22, and 15% of the total manure N from Diets T2High and T2Low. Manure NH+4 concentration and pH were positively related to the dietary crude protein level. Manure from cattle‐fed diets T1Med and T1Low were applied to soil at two rates to determine short‐term N availability for three plantings of corn (Zea mays L.) grown for 30 d each in the greenhouse. The recovery of manure and fertilizer N in the plants and the soil for the first two plantings was 48, 31, and 103% for the T1Med, T1Low, and inorganic N treatments, respectively. Whole farm N utilization for diets T2High and T2Low were estimated at 18 and 23%, respectively. Feeding diets lower in crude protein increases efficiency of N on the dairy farm, decreases NH3 emissions following excretion but also decreases the short‐term N availability of the manure.
Soluble Trace Metals in Alkaline Stabilized Sludge Products
Authors: McBride M. B. 
Published: July 2010

AbstractThe application of alkaline sludge products as liming agents to agricultural soils is now commonplace. Laboratory investigations of water extracts from two alkali‐stabilized sludge products used in New York State reveals that 40 to 50% of the total Cu, 15 to 25% of the total Ni, and 11 to 13% of the Mo dissolved out of the sludge product into water, whereas much smaller fractions of the Cd, Zn, Pb, Ag, and Hg were immediately water soluble. Speciation techniques, including differential pulse anodic stripping voltammetry (DPASV), electron spin resonance (ESR), and computer speciation calculations (MINEQL+), indicated that the high solubility of Cu and Ni was a result of complexation with dissolved amines or amino acids in the alkaline (pH12) water extracts. Because of the high affinity of both Cu2+ and Ni2+ for N‐ligands in amines, these metals were mobilized much more than Pb, Zn, or Cd. The low solubilities of Ag and Hg may indicate that they were present in the sludge product as the insoluble metallic or sulfide forms. Prolonged exposure of the alkaline extracts to air caused CO2 to gradually lower the solution pH to 8.1 forming a CaCO3 precipitate. However, the dissolved Cu and Ni concentrations did not diminish with pH, indicating that the metal‐organic complexes were sufficiently stable at pH 8.1 to inhibit metal precipitation with the CaCO3. The results suggest potential for the transport of certain heavy metals from land‐applied alkaline sludges into surface waters and shallow groundwater in some situations.
Mercury and Methylmercury in Decomposing Vegetation of a Pristine and Impounded Wetland
Authors: Heyes A. , Moore T. R , Rudd J. W. M. 
Published: July 2010

AbstractMass loss, methylmercury (MeHg), and total mercury (T‐Hg) concentrations were measured in sedge, spruce needles, and Sphagnum moss decomposing in a headwater bog and an impounded riparian wetland. No significant differences in the rates of decomposition were apparent for like tissues among sites. Although concentrations of T‐Hg increased in some tissues, T‐Hg mass was lost from most tissues during decomposition. In the reservoir, approximately 75, 50, and 45% of the initial T‐Hg mass was released from the sedge, needles, and moss, respectively, compared to 45, 0, and 40% in the headwater wetland. Therefore, we propose impoundment promotes the release of T‐Hg during decomposition. Concentrations, masses, and percentages of MeHg decreased in all tissue types at the headwater‐dry site and MeHg concentrations increased in all tissue types at the headwater‐wet and impounded sites. At the headwater‐wet site, the mass of MeHg only increased in the moss (500%) and T‐Hg occurring as MeHg averaged 6% in sedge, 1% in needles, and 7% in moss compared to initial values of 4, 0.5, and 1%. At the impounded sites, the amount of MeHg in the needles and moss increased by approximately 700 and 500%, respectively. Also, T‐Hg occurring as MeHg averaged 12% in sedge, 6% in spruce needles, and 17% in moss. We conclude that decomposition of fresh plant tissue under anoxic conditions increases their MeHg mass and impoundment promotes this process. This increase in tissue MeHg mass is most likely the result of in situ methylation of previously accumulated inorganic Hg.
Use of BIOLOG for the Analysis of Microbial Communities from Zinc‐Contaminated Soils
Authors: Kelly John J. , Tate Robert L. 
Published: July 2010

AbstractThe BIOLOG procedure, a useful method for assessing differences in community structure between soil microbial communities, could be used to determine the impact of metal contamination of soils and reclamation of these soils; however, high metal levels may affect the results of the BIOLOG assay. This project determined that Zn in soils interfered with extraction of soils with phosphate buffer by forming an insoluble precipitate. High Zn levels were also shown to prevent color formation and to cause false positive readings in the BIOLOG assay. The objectives of this project were developing and validating a modified BIOLOG method for use in the presence of high Zn concentrations. Substitution of 0.1 M Tris buffer for phosphate buffer prevented precipitate formation during the extraction step; however, extraction with Tris buffer could result in high Zn concentrations in the BIOLOG inoculant. Zinc concentrations of >50 mg L−1 in the inoculant were shown to result in false positive readings due to production of a precipitate in the wells. Raising the pH of the extractant to above 7.0 or removal of the Zn with cation exchange resin relieved this problem. Analyses of BIOLOG data showed that neither raising the extractant pH nor using cation exhange resin resulted in observable changes in BIOLOG metabolic profiles. However, use of Tris buffer in place of phosphate buffer did result in a slight change in BIOLOG metabolic profiles. Thus, the nature of the extracting buffer must be considered when analyzing experimental results. The methods developed herein allow use of the BIOLOG procedure for soils with high metal concentrations.
Fluxes of Nitrous Oxide and Molecular Nitrogen from Irrigated Soils of Catalonia (Spain)
Authors: Teira‐Esmatges M. R. , Van Cleemput O. , Porta‐Casanellas J. 
Published: July 2010

AbstractNitrous oxide (N2O) is a gas of environmental concern that can be emitted during nitrification and denitrification. Molecular nitrogen (N2) is the ultimate product of denitrification. The emission of both gases represents an economic loss. This study quantified daily and seasonal N2O and N2 emissions from three benchmark arable soils sown with maize (Zea mays L.) in Catalonia (northeast Spain) during the irrigation season, and identified the major factors and processes determining these emissions. The N2O was sampled using the closed chamber method, and N2 from N2O that accumulated with the acetylene inhibition method, simultaneously in the field. At water‐filled pore space (WFPS) >70%, losses amounted to 389 g of N2O‐N ha−1 d−1 from the El Pinell site, 144 g of N2O‐N ha−1 d−1 from the Barbens site, and 125 g of N2O‐N ha−1 d−1 from the Bellpuig site. Most of the N was lost through complete denitrification. Up to 640 g of N2‐N ha−1 d−1 were lost from the El Pinell site, 1438 g of N2‐N ha−1 d−1 from the Barbens site, and 233 g of N2‐N ha−1 d−1 from the Bellpuig site. Negative N2O and N2 fluxes were found. Total (N2O + N2)‐N losses represent 13.6% of the N applied at the El Pinell site, 8.6% at the Barbens site, and 1.7% at the Bellpuig site. Denitrification was the main source of emission. Significant N2O‐N losses due to nitrification were also measured. The potential for gaseous N losses from these soils at <40% WFPS is low (it averaged 0.01 g of N ha−1 d−1 from the three sites).
Phytoaccumulation of Trace Elements by Wetland Plants: I. Duckweed
Authors: Zayed Adel , Gowthaman Suvarnalatha , Terry Norman 
Published: July 2010

AbstractThere has been much interest recently in the use of constructed wetlands for the removal of toxic trace elements from wastewaters. Wetland plants play an important role in the trace elements removal process. It is not known, however, which wetland plant species absorb specific trace elements at the fastest rates. Such knowledge is essential to maximize the efficiency of trace element removal by wetlands. In this study, we investigated the potential of duckweed (Lemna minor L.) to accumulate Cd, Cr, Cu, Ni, Pb, and Se when supplied individually in a nutrient solution at a series of concentrations ranged from 0.1 to 10 mg L−1. The results show that under experimental conditions, duckweed proved to be a good accumulator of Cd, Se, and Cu, a moderate accumulator of Cr, and a poor accumulator of Ni and Pb. The highest concentrations of each trace element accumulated in duckweed tissues were 13.3 g Cd kg−1, 4.27 g Se kg−1, 3.36 g Cu kg−1, 2.87 g Cr kg−1, 1.79 g Ni kg−1, and 0.63 g Pb kg−1. Duckweed exhibited some symptoms of toxicity (e.g., reduced growth, chlorosis) at higher levels of element supply (except for Cr). The toxicity effect of each trace element on plant growth was, in descending order of damage, Cu > Se > Pb > Cd > Ni > Cr. We conclude that duckweed shows promise for the removal of Cd, Se, and Cu from contaminated wastewater since it accumulates high concentrations of these elements. Further, the growth rates and harvest potential make duckweed a good species for phytoremediation activities.
Realizing Basic Research in Applied Environmental Research Projects
Authors: Bouma J. 
Published: July 2010

AbstractPolitical pressure is exerted in many countries to focus agricultural and environmental research on market‐driven applications, rather than on basic research. This can become a real problem because our expertise needs to be continuously fed with new ideas originating from basic research. Rather than rigidly oppose the trend, we advocate research procedures where applied and basic research logically fit together in so‐called research chains. More time should be spent in any project on defining the most efficient research chain in close interaction with stakeholders, comparing relatively simple (and inexpensive) procedures using expert knowledge with more complicated (and expensive) ones that may include basic research using sophisticated methodology. Research chains are illustrated for case studies on soil acidification and precision agriculture, while chains are described for organic farming. Basic research is defined differently and more effectively when it is part of a research chain, as compared with independent formulation. Information technology plays an increasingly important role in the evolving interactive research paradigm where the former linear research model is replaced by the hourglass model, which requires an interdisciplinary research approach and defines basic research on issues where existing knowledge is clearly inadequate. Application of simulation modeling and geostatistics allows expression in terms of risks that threshold values of sustainability indicators are exceeded. Regulators have the prime responsibility to decide which risks are acceptable. Researchers offer options rather than judgements. In addition to realizing research chains including basic research, independent funding for basic research in promising future areas of work is necessary as well.
Alachlor Dissipation in Shallow Cropland Soil
Authors: Weed D. A. J. , Kanwar R. S. , Cambardella C. , Moorman T. B. 
Published: July 2010

AbstractA soil‐column laboratory experiment and a 2‐yr field‐sampling study evaluated the overall dissipation of alachlor [2‐chloro‐N‐(2,6‐diethylphenyl)‐N‐(methoxymethyl) acetamide]. Theses studies also measured the effect of no‐till and chisel‐plow tillages on alachlor leaching and dissipation. In the top 30 cm layer of soil, the overall half‐life was 3 d or less, and the time to 90% dissipation ranged from 17 to 30 d. In no‐fill soil, alachlor dissipated slightly faster, and more was transported into the 10 to 30 cm soil layer. Weather conditions promoting the movement of alachlor into the soil, however, weakened the effect of tillage on the dissipation rate. Most of the alachlor present in the soil, regardless of tillage, was found in the top 10 cm at all times. Of the alachlor applied to 30‐cm tall soil columns, only 0.4% was removed by water flowing from chisel‐plow columns and 1.6% from no‐till columns. The results show that tillage was not a key factor in alachlor dissipation and leaching. Alachlor leaching was also a minor component in overall dissipation.
Groundwater Quality under Conventional and No Tillage: II. Atrazine, Deethylatrazine, and Metolachlor
Authors: Masse L. , Patni N. K. , Jui P. Y. , Clegg B. S. 
Published: July 2010

AbstractThe effect of no tillage (NT) and conventional tillage (CT) on the contamination of shallow groundwater by atrazine (2‐chloro‐4‐ethylamino‐6‐isopropylamino‐s‐triazine), deethylatrazine (2‐chloro‐4‐amino‐6‐isopropylamino‐s‐triazine), and metolachlor (2‐chloro‐N‐(ethyl‐6‐methylphenyl)‐N‐(2‐metoxy‐1‐methylethyl) acetamide) at nominal depths of 1.2, 1.8, 3.0, and 4.6 m was studied during four successive crop‐years in four corn (Zea mays L.) fields with loam soil. Atrazine and deethylatrazine were almost always present in the shallow groundwater. Atrazine concentrations were below the U.S. Environmental Protection Agency (USEPA) lifetime health advisory (LHA) of 3 µg/L in more than 99% of the 920 groundwater samples from the two tillage treatments. Atrazine concentrations, although low, were significantly higher under NT than CT (P < 0.05) at the 1.8 and 3.0 m depths. Deethylatrazine concentrations were also low but were generally higher than those of the parent compound. They were significantly higher under NT than CT at the 1.2 and 1.8 m depths (P < 0.1), as well as at 3.0 m (P < 0.01). Metolachlor was detected in only 25% of the samples and concentrations were well below the USEPA LHA of 100 µg/L. There was no tillage treatment effect on metolachlor concentration. Results from this study suggest a low potential for serious pollution of shallow groundwater from application of atrazine and metolachlor at agronomically recommended rates in tile‐drained corn fields in cold humid regions under both CT and NT practices. However, atrazine leaching appears to be greater under NT than under CT.
Evaluation of Localized Compaction and Doming to Reduce Anion Leaching Losses Using Lysimeters
Authors: Ressler D. E. , Horton R. , Baker J. L. , Kaspar T. C. 
Published: July 2010

AbstractFertilizer N that leaches from the root zone is not available for uptake by plants and can be transported to surface waters by subsurface drains, where it is considered a contaminant. Localized soil compaction and doming (LCD) to divert precipitation or irrigation water around the zone of fertilizer injection may be one way to reduce nitrate (NO−3) leaching from agricultural fields. This study was designed to determine whether anion tracer transport through soil profiles to subsurface drains could be delayed by modified application methods, specifically (i) injection using a conventional knife shank; (ii) broadcast application; and (iii) injection and covering using an LCD injector. Three fluorobenzoate tracers, which move similarly to NO−3 through soil, were applied to eight lysimeters at 63 kg ha−1 using the three application treatments. Each treatment contained an individual tracer. Two rainfall intensity treatments were imposed, four lysimeters per rainfall intensity treatment. All lysimeters received 50 mm of simulated rain 3 d after chemical application. A storm of this magnitude occurs once in 5 yr in Iowa. There were no differences in cumulative tracer leaching between the different rainfall intensity treatments. At the end of 6 mo, 5% of the tracer applied by a conventional knife shank leached to the subsurface drains, 4% applied as broadcast leached, and 1% applied by the LCD leached. At 18 mo, corresponding values were 25, 17, and 13%. These results suggested that soil modification in the fertilizer injection zone was a simple and effective way to reduce anion leaching.