bluuebunny/crossref_metadata_2025 huggingface dataset:
Plant Response to Fish Farming Wastes in Volcanic Soils
Authors: Mazzarino M. J. , Walter I. , Costa G. , Laos F. , Roselli L. , Satti P.
Published: July 2010

Agricultural use of aquaculture wastes appears to be a sound ecological and economical means to improve soil fertility and to decrease the potential for adverse water quality impacts in South Argentina. A 3‐mo greenhouse experiment with ryegrass (Lolium perenne L.) was conducted to determine plant availability of N and P from aquaculture wastes and compare results with previous laboratory incubations. Treatments included: (i) wastes taken from sediments under cages in a 3‐yr‐old fish farm (EA) applied at 40 and 80 Mg ha−1; (ii) wastes taken from sediments under cages in an 8‐yr‐old farm (LM), applied at 10 and 20 Mg ha−1; (iii) the lowest waste rates amended with 50 kg ha−1 synthetic N; (iv) four synthetic fertilizer treatments including a single N rate of 80 kg N ha−1 and four P levels of 30, 40, 60, and 80 kg P ha−1, and (v) a no‐fertilizer control. Although total N and P were higher in LM than in EA, and N mineralization rates in lab incubations were similar (13%), ryegrass yields and N uptake were much higher in EA than in LM. When mineralized N was estimated as the difference between added N and total N uptake, values were 50 to 63% for EA and 5 to 14% for LM. Ryegrass yields were approximately as follows: EA > FI > LM > Control. Synthetic fertilizer treatments showed the lowest values of P utilization efficiency, residual Olsen‐P in soil and plant P uptake in biomass, and the highest P retention in soils. The lowest waste rates with addition of N produced comparable ryegrass yields with the highest rates. Results emphasize: (i) the need to include living plants in mineralization potential evaluations to avoid significant errors in nutrient cycling models, and (ii) the importance of organic amendments in ameliorating plant P availability in high P‐fixing volcanic soils.
Potential Release of Phosphorus from Soil Mixed with Sewage Sludge
Authors: Rydin Emil , Otabbong Erasmus
Published: July 2010

Retention capacities of phosphorus (P) in three soils (sandy loam, sandy clay, and sandy clay loam) and in soil mixed with 50 g kg−1 (5% ww) digested sewage sludge (Al‐ or Fe‐precipitated) were measured in a laboratory study. Artificial rainwater, continuously leached through different samples, released about 15% of the total‐P content (0.6–1.1 g P kg−1) of the soils. Adding Fe‐precipitated sludge to the soil approximately doubled the P‐concentration (1.1 to 1.7 g P kg−1) in the samples, and 20% was released. Up to 43% of the total‐P (1.1 g P kg−1) was released when Al‐precipitated sludge was mixed with the sandy loam soil. The release process was described by a first‐order decay equation, and release rates between 0.04 and 0.07 d−1 or 35 mm water passing−1 were obtained. The released amounts could be considered as potential mobile phosphate under the experimental conditions used and are compared with potentially crop‐available P. Phosphorus fractionation revealed that P adsorbed to Fe and Al was more or less exhausted, declining from about 35% at the start of the experiment to 5% of tot‐P by the end. The inert P‐pool increased, indicating that P transformations favored the production of more stable compounds. The accumulation of P in urban regions and the risk for nonpoint pollution of surface‐ and groundwaters are discussed.
Trace Element Composition of Fertilizers and Soil Amendments
Authors: Raven K. P. , Loeppert R. H.
Published: July 2010

The use of fertilizers and soil amendments has raised concern regarding the toxic accumulation of their trace components in the environment. The objective of this research was to evaluate the trace element and heavy metal composition of a wide variety of fertilizers and soil amendments. Thirty‐five elements, including priority pollutants, were determined in 24 materials. A microwave HNO3‐HF‐H2O2‐H3BO3 digestion procedure was used to dissolve the samples. Selected solid samples were directly analyzed by neutron activation analysis, while atomic absorption and inductively‐coupled plasma atomic emission spectrometric determinations were carried out on the digests. The trace element and heavy metal concentrations generally decreased in the following sample order: rock phosphate > sewage sludge > phosphorus fertilizer > organic amendments and liming materials > K fertilizers > N fertilizers. Relatively high concentrations of toxic elements in the sewage sludge, rock phosphate, and phosphorus fertilizer samples suggest that these materials should be the primary target materials for environmental evaluations.
Logistic Model of Nitrate in Streams of the Upper‐Midwestern United States
Authors: Mueller David K. , Ruddy Barbara C. , Battaglin William A.
Published: July 2010

Nitrate in surface water can have adverse effects on aquatic life and, in drinking‐water supplies, can be a risk to human health. As part of a regional study, nitrate as N (NO3‐N) was analyzed in water samples collected from streams throughout 10 Midwestern states during synoptic surveys in 1989, 1990, and 1994. Data from the period immediately following crop planting at 124 sites were analyzed using logistic regression to relate discrete categories of NO3‐N concentrations to characteristics of the basins upstream from the sites. The NO3‐N data were divided into three categories representing probable background concentrations (<3 mg L−1), elevated concentrations (3–10 mg L−1), and concentrations that exceeded the U.S. Environmental Protection Agency maximum contaminant level (MCL) for drinking water (>10 mg L−1). Nitrate‐N concentrations were positively correlated to streamflow, upstream area planted in corn (Zea mays L.), and upstream N‐fertilizer application rates. Elevated NO3‐N concentrations were associated with poorly drained soils and were weakly correlated with population density. Nitrate‐N and streamflow data collected during 1989 and 1990 were used to calibrate the model, and data collected during 1994 were used for verification. The model correctly estimated NO3‐N concentration categories for 79% of the samples in the calibration data set and 60% of the samples in the verification data set. The model was used to indicate where NO3‐N concentrations might be elevated or exceed the NO3‐N MCL in streams throughout the study area. The potential for elevated NO3‐N concentrations was predicted to be greatest for streams in Illinois, Indiana, Iowa, and western Ohio.
Naturally High Nitrate Concentrations in Groundwaters from the Sahel
Authors: Edmunds W. M. , Gaye C. B.
Published: July 2010

Nitrate concentrations in excess of 50 to 100 mg L−1 NO3‐N are found widely in interstitial waters from unsaturated Quaternary sands in northern Senegal. These high concentrations and correspondingly enhanced NO3/Cl ratios are being produced in the soil zone beneath both uncultivated and rain‐fed cultivated areas. High nitrate (avg. 11 mg L−1 NO3‐N) is also found extensively in shallow groundwaters. The NO3‐N signature is preserved as a result of the aerobic conditions. The unsaturated zone contains a history of N inputs over a period of approximately 50 to 400 yr. Variations in the NO3/Cl ratio are mainly related to the growth of natural or introduced leguminous vegetation. There is also evidence that high ratios relate to wetter and low values to more arid climatic periods. These results, taken together with evidence from other parts of the world, demonstrate that high nitrate concentrations are likely to be a widespread and established phenomenon of groundwaters in semiarid regions.
Nutrients and Sediment in Runoff from Creeping Bentgrass and Perennial Ryegrass Turfs
Authors: Linde Douglas T. , Watschke Thomas L.
Published: July 2010

Although scientists have found little transport of nutrients to date in runoff from turfgrasses, more research is needed on a wider range of soil conditions and management scenarios. This study was designed to assess nutrient and sediment transport from creeping bentgrass (Agrostis palustris Huds.) and perennial ryegrass (Lolium perenne L.) turfs and to assess the influence that vertical mowing had on sediment transport. Sloped plots of bentgrass and ryegrass, maintained similar to a golf fairway, were irrigated to force runoff for the generation of runoff and leachate water samples. About 12 h before each runoff event, irrigation was used to equilibrate soil moisture for all plots. For four events, plots were treated with fertilizer at a rate of 4.9 g N m−2, 0.3 g P m−2, and 4.1 g K m−2 about 4 h after pre‐event irrigation and 8 h before runoff. For another four events, plots were verticut 6 h before runoff. Water samples were analyzed for NO3‐N, total Kjeldahl‐N (TKN), phosphate, and sediment. Mean NO3‐N concentrations rarely exceeded 1 mg L−1. Phosphate and TKN concentrations and losses significantly increased when runoff was forced 8 h after fertilization. On average for these events, 11% of applied P and 2% applied N was detected in runoff and 14% applied P and 3% applied N was detected in leachate. For all other events, nutrient concentrations and losses were consistently lower. Vertical mowing had little affect on sediment transport. Sediment transport from both turfs averaged 0.8 kg ha−1. On golf fairways, off‐site movement of nutrients may happen if runoff occurs soon after granular fertilizer is applied to a nearly saturated soil.
Plant Toxicity and Plant Uptake of Fluorobenzoate and Bromide Water Tracers
Authors: Bowman Robert S. , Schroeder Jill , Bulusu Rao , Remmenga Marta , Heightman Rose
Published: July 2010

The plant toxicity and plant uptake of pentafluorobenzoate (PFBA); 2,6‐difluorobenzoate (2,6‐DFBA); 3,4‐difluorobenzoate (3,4‐DFBA); and KBr were determined in greenhouse experiments. The germination of 11 different crop species was not inhibited by the fluorobenzoates at concentrations below 250 mg L−1 and KBr at concentrations below 500 mg L−1. Alfalfa (Medicago sativa L.), barley (Hordeum vulgare L.), and canola were planted in sealed pots in which different concentrations of the tracers were maintained in the soil solution. The threshold for plant growth inhibition by the fluorobenzoates was between 50 and 125 mg L−1; KBr did not inhibit growth even at 1000 mg L−1. At the no‐growth‐effect level of 50 mg L−1, 0.1 to 55% of the added fluorobenzoates or Br was recovered from the tissue of seedling alfalfa, barley, or canola. As much as 65% of the added fluorobenzoates was not recovered; the fluorobenzoates were presumably degraded in the soil or metabolized fallowing plant uptake. All of the added Br was recovered. The greatest mass loss was observed for 3,4‐DFBA (the isomer with the highest negative‐log acid dissociation constant); otherwise there was no correlation of plant response with fluorobenzoate properties. The results show that fluorobenzoates and Br can be readily taken up by growing plants, and that fluorobenzoate mass losses may occur when plants are present.
Tracer and Nitrate Movement to Groundwater in the Northern Great Plains
Authors: Schuh W. M. , Klinkebiel D. L. , Gardner J. C. , Meyer R. F.
Published: July 2010

An experiment was conducted to study the movement of surface‐applied tracers and fertilizer to groundwater on an agricultural field under dryland farming practices. Movement of surface‐applied bromide, chloride, and fluoride tracers, and fertilizer nitrate (NO3) through a coarse‐loamy glacial till soil and vadose zone to saturated glacial till at about 3 to 4 m, and to a confined aquifer at 6.8 m, were monitored for 5‐yr. Crop treatments were a dryland rotation of wheat (Triticum aestivum L.), soybean [Glycine max (L.) Merr.], and sunflower (Helianthus annuus L.). Applied bromide, chloride, and NO3 could be detected in trace amounts at all levels, including the aquifer, within a few days after application and following large summer storms. Within the root zone, NO3 and chloride concentrations varied with root extraction and application placement. The largest stable concentration of solute occurred within the shallow vadose zone beneath the root zone. Below the root zone, tracer and NO3 concentrations decreased exponentially with depth. Following a large rainfall the shallow vadose layer served as a “feeder zone” for solute movement to deeper layers. Elevated concentrations following recharge events were spatially sporadic, occurring at some locations and not at others. Spatially variable and temporary increases in solute concentrations were caused by spatially variable recharge, governed by microtopographic controls. Water concentrated in microtopographical “low” areas and moved in concentrated plugs to the water table carrying solute. NO3‐N did not increase in the saturated till or the aquifer over the 5‐yr period.
Prediction of Cesium‐134 and Strontium‐85 Crop Uptake Based on Soil Properties
Authors: Roca M. C. , Vallejo V. R. , Roig M. , Tent J. , Vidal M. , Rauret G.
Published: July 2010

Nowadays, there is still the need to improve the quantification of parameters that affect radionuclide mobility. With this aim, radiocesium and radiostrontium soil‐to‐plant transfer was measured in lysimeters in a Calcic Luvisol, loamy soil and in a Fluvisol, loam‐sandy soil, using lettuce [Lactuca sativa L. cv. Kinemontepas] and pea plants [Pisum sativum L. cv. Kelvedon Wonder]. Weighted Concentration Ratios (WCR), expressed as kg soil/kg plant, were calculated for different growth stages. Weighted Concentration Ratios were in general higher for 85Sr than for 134Cs, and also higher in the loam‐sandy than in the loamy soil. To predict plant uptake, we evaluated a set of soil properties to define a prediction factor for the relative transfer in the two soils using cation exchange capacity (CEC) and radionuclide available fraction (fav)for radiostrontium, and soil solution composition, solid‐liquid distribution coefficient, and radionuclide available fraction for radiocesium. The ratios of WCR in the loam‐sandy and loamy soil were compared with the prediction factor. There was good agreement in lettuce for 85Sr (ratio of WCR was 5.4 for seedling and 3.9 for commercial samples, whereas prediction factor was 3.1) and for 134Cs (ratio of WCR was 5.1 for seedling and 5.5 for commercial samples, the prediction factor being 5.1), although for pea only the relative root uptake of radiocesium in seedling pea was well predicted (the ratio of WCR was 8.8, the prediction factor being 9.1). These soil parameters improved former predictions based solely on the fav, although factors depending on plant physiology should be better evaluated.
Prediction of Parameters Describing Phosphorus‐Desorption Kinetics in Soils of Galicia (Northwest Spain)
Authors: García‐Rodeja I. , Gil‐Sotres F.
Published: July 2010

The risk of eutrophication due to loss of soil phosphorus (P) in runoff can be assessed by means of models simulating the release of soil P and its transport in runoff. One limitation of these models is that they seldom take into account the kinetics of P desorption from soil. In this work, to facilitate inclusion of kinetic aspects of P desorption in these models, equations to estimate parameters describing P‐desorption kinetics from soil properties were developed. A modified Freundlich equation and several equations commonly used to describe P‐desorption kinetics were fitted to kinetic data for P desorption from 31 surface horizons of soils of Galicia (Northwest Spain). Correlations were then determined between the parameters of these kinetic equations and soil physicochemical properties. Correlated properties were Al and Fe content and soil P fixation indices determined 1 d and 1 wk after P addition. By means of stepwise multiple regression analysis, equations were obtained that allow estimation of parameters describing P‐desorption kinetics from soil properties, the dose of added P, and the soil‐P contact time.
A Water Balance Study of Four Landfill Cover Designs Varying in Slope for Semiarid Regions
Authors: Nyhan J. W. , Schofield T. G. , Starmer R. H.
Published: July 2010

The goal of waste disposal in landfills is to reduce risk to human health by isolating contaminants until they no longer pose a hazard. To achieve this, the performance of a landfill cover design without an engineered barrier (Conventional Design) was compared with designs containing either a hydraulic barrier (USEPA Design) or two capillary barriers (Loam and Clay Loam Capillary Barrier Designs). Water balance parameters were measured at 6‐h intervals for these designs in 1.0 by 10.0 m plots with downhill slopes of 5, 10, 15, and 25%. Whereas runoff generally accounted for only 2 to 3% of the precipitation losses on these designs from December 1991 through July 1995, similar values for evaporation ranged from 86 to 91%. Evaporation usually increased with increases in slope in our field plots; the Conventional Design at slopes of 5 and 25% exhibited 139 and 162 cm of evaporation, respectively. Consequently, interflow and seepage usually decreased with increasing slope: interflow decreased from 10.7 to 1.5 cm for the Clay Loam Capillary Barrier Design at slopes of 5 and 25%. Although seepage comprised up to 10% of the precipitation on the Conventional Design, seepage did not occur in either the USEPA design or the capillary designs at the larger slopes.
Spatial Variability of Nitrous Oxide Fluxes and Controlling Soil and Topographic Properties
Authors: Ball Bruce C. , Horgan Graham W. , Clayton Helen , Parker John P.
Published: July 2010

Spatial heterogeneity of nitrous oxide (N2O) flux was characterized along with various soil chemical, physical, and microtopographical properties to identify those determining flux in fertilized grassland in spring 1993 and in fertilized winter wheat in spring 1994. Measurements were made at random locations within regular grids. Nitrous oxide emission was measured using closed chambers at 84 locations in each grid, spread over 2 d. The ranges of emissions from the grassland and from the winter wheat were 0 to 134 and 0 to 26.4 g N2O‐N ha−1 d−1. Variograms for N2O emission and for concentrations in the soil atmosphere at 100 mm depth indicated that spatial dependence was weak at both sites. Of the other properties, pH and nitrate showed weak autocorrelation but none of the soil physical properties showed any significant spatial dependence. The results of multiple linear regression suggested that denitrification was the main N2O production process at the grassland site, but nitrification may have been equally important at the drier winter wheat site. At both sites, the highest N2O emissions were associated with areas of a few square centimeters to a few square meters, lying below the average slope. Use of a partial least squares regression technique to predict nitrous oxide flux revealed the contribution of air permeability in addition to nitrate, ammonium, and soil water contents. Our analyses suggested that nitrous oxide production, consumption, and transport processes varied markedly with depth (over a few centimeters) near the soil surface.
Adsorption of Trace Metals by Tension Lysimeters: Nylon Membrane vs. Porous Ceramic Cup
Authors: Wenzel W. W. , Sletten R. S. , Brandstetter A. , Wieshammer G. , Stingeder G.
Published: July 2010

Lysimeters constructed of polyacrylic and fitted with either a porous nylon membrane or a porous ceramic cup were tested for their adsorption characteristics with respect to Pb, Cr, Cu, As, Cd, Co, Mn, Ni, and Zn. Laboratory tests were conducted at pH 4, 5, and 6 using metal concentrations that are representative of natural soil solutions. The ceramic lysimeters significantly lowered the concentrations of Cd, Co, Mn, Ni, and Zn, and almost completely removed Pb, Cr, Cu, and As from solution. The nylon lysimeters had virtually no effect on metal concentrations at pH 4 to 5, and only slightly decreased the concentrations of As, Cr, Cu, and Pb at pH 6. Based on field experience, an optimized design of the nylon lysimeter is presented using double nylon membranes to improve the mechanical resistance.
Use of Rhodamine WT to Facilitate Dilution and Analysis of Atrazine Samples in Short‐Term Transport Studies
Authors: Cook Sabrina M. F. , Linden Dennis R.
Published: July 2010

Because pesticide transport studies often require many samples, and certain pesticide analytical methods have small detection ranges, repeat analyses of samples that are outside of this range can be costly. Dye‐tracers often have a lower analysis cost than pesticides and can be visibly diluted to within detection range. We wanted to see if we could predict the dilution factor necessary for atrazine analysis by using a visible dye‐tracer, rhodamine WT. Rhodamine WT and Aatrex‐4L atrazine (2‐chloro‐4‐ethylamino‐6‐isopropylamino‐1,3,5‐triazine) were surface applied to large, intact soil cores taken from three replications of 12‐yr no‐till, 2‐yr no‐till, and 12‐yr moldboard plow treatments. Cores were then rained on for 1 h with an oscillatinghead rainfall simulator at intensity = 50 mm h−1. Based on rhodamine WT concentrations, runoff, leachate, and soil extract samples were diluted to near mid‐atrazine‐detection range, on a logarithmic scale (0.9 µg L−1), for atrazine analysis by enzyme‐linked immunosorbant assay (ELISA). Only 6% of runoff and leachate samples (ntotal=262) needed additional dilution and only 0.5% of soil extract samples (ntotal=174) needed additional dilution. No predictions resulted in overdilution of samples. Rhodamine WT concentration was shown to be an effective predictor of dilution factor necessary for atrazine analysis in short‐term transport through this soil.
Impacts to a Coastal River and Estuary from Rupture of a Large Swine Waste Holding Lagoon
Authors: Burkholder JoAnn M. , Mallin Michael A. , Glasgow Howard B. , Larsen L. Michael , McIver Matthew R. , Shank G. Christopher , Deamer‐Melia Nora , Briley David S. , Springer Jeffrey , Touchette Brant W. , Hannon Elle K.
Published: July 2010

We tracked a swine waste spill (4.13 × 107 L) into a small receiving river and estuary. After 2 d, a 29‐km freshwater segment that the wastes had traversed was anoxic, with ca. 4000 dead fish floating and hung in shoreline vegetation. Suspended solids, nutrients, and fecal coliforms were 10‐ to 100‐fold higher at the plume's edge (71.7 mg SS/L, 39.6 mg NH+4‐N/L, and >1 × 106 cfu/100 mL, respectively; cfu, colony forming units, SS; suspended solids) than in unaffected reference sites. Elevated nutrients and an oxygen sag from the plume reached the main estuary after ca. 5 d. Increased phytoplankton production was contributed by noxious algae, Synechococcus aeruginosa and Phaeocystis globosa (108 and 106 cells/mL, respectively) after 7 to 14 d. The toxic dinoflagellates, Pfiesteria piscicida and a second Pfiesteria‐like species, increased to potentially lethal densities (103 cells/mL) that coincided with a fish kill and ulcerative epizootic. After 14 d, water‐column fecal coliforms generally were at 102 to 103 cfu/100 mL. But where the plume had hovered for the first 5 d, surface sediments mostly yielded ≥104 cfu/100 mL slurry, and after 61 d densities in surficial sediments were still at 103 to 104 cfu/100 mL. Dinoflagellate and euglenoid blooms developed and moved downestuary, where they were detected after 61 d. This study documented acute impacts to surfacewaters from a concentrated swine operation, and examined some environmental policies affecting the intensive animal operation industry.
Diuron and Simazine Losses to Runoff Water in Mediterranean Vineyards
Authors: Lennartz Bernd , Louchart Xavier , Voltz Marc , Andrieux Patrick
Published: July 2010

The Mediterranean climate is characterized by a hot and dry summer where occasional storm events induce erosion and runoff. The high leaching potential of pesticides to surface waters under such climate conditions are not in relation to the main body of data that originated from summer‐rain row‐crop scenarios. In this 2‐yr study we monitored runoff discharge and concentrations of the two soil applied herbicides diuron [3‐(3,4‐dichlorphenyl)‐1,1‐dimethylurea] and simazine [6‐chloro‐N2,N4‐diethyl‐1,3,5‐triazine‐2,4‐diamine] from two field sites—one tilled and one no‐till—cropped with grapevine (Vitis vinifera L.; Cinsault and Aramon, respectively). Despite a time lag of 140 d in 1994 between chemical application and first runoff event, diuron concentrations in overland flow exceeded 200 µg L−1 at the no‐till site. In 1995 the first strong rainfall‐runoff event following application carried >87 and 60% of the respective seasonal simazine and diuron loss at both sites, although it accounted for <17 and 7% of the total runoff volume at the no‐till and tilled site, respectively. At the no‐till site, seasonal diuron loss during 1995 was 1.71% of applied; the corresponding value for simazine was 1.25%. Only 0.68 and 0.79% of the respective applied diuron and simazine mass were washed from the tilled field, reflecting differences in runoff volume between sites. Pesticide losses depended primarily on runoff volume and intensity. Event average herbicide concentrations in surface runoff followed an exponential decay over time. Estimated first order rate coefficients were at least twice as large as those derived from soil samples using the alcoholic solvent extraction technique. The decreasing water availability with time compared with the herbicide content at the soil surface indicated an increasing adsorption with time.
Biodegradation of Petroleum Hydrocarbons in Soil as Affected by Heating and Forced Aeration
Authors: Yeung P. Y. , Johnson R. L. , Xu J. G.
Published: July 2010

Quantifying the biodegradation rate of organic contaminants is important in designing and evaluating bioremediation treatments and facilities. To study the effects of temperature and forced aeration on the biodegradation rate, a soil collected from a pipeline break site and contaminated with crude oil was bioremediated in a field‐operated bioreactor near Nevis, AB, Canada under four treatments: a control with ambient temperature (averaging 20°C) and no forced aeration; heating alone (averaging 35°C); forced aeration alone (air flux was 0.4 1 min−1 m−2); and both heating and forced aeration. The soil was aggregated, amended with N and P fertilizers and packed 15‐cm deep to a bulk density of 0.65 Mg m−3 in the bioreactor. The effect of temperature on the biodegradation rate of hydrocarbons was also studied under laboratory conditions for temperatures ranging from 5 to 50°C. Both heating and forced aeration significantly affected the biodegradation of hydrocarbons, but the effect of the former was greater. Under laboratory conditions, the biodegradation rate of hydrocarbons increased with temperatures, peaking between 30 and 40°C. The half‐lives of the hydrocarbons remaining in soil in the field‐operated bioreactor were 105 d for both the heating alone and the heating and forced aeration treatments, 182 d for the forced aeration treatment and 248 d for the control.
Acetylene Transport In Shallow Groundwater for Denitrification Rate Measurement
Authors: Bragan R. J. , Starr J. L. , Parkin T. B.
Published: July 2010

Nitrate (NO3) concentrations frequently diminish in shallow groundwater (<3 m) when laterally transported through the soils of riparian zones and intermittent wetlands. Denitrification may be the major mechanism for this loss, but lack of suitable methods for direct measurement of denitrification rates in shallow groundwater limit the ability of field studies to verify this. The objective of this study was to determine if adequate acetylene (C2H2) concentrations can be maintained in the intermittently saturated, near surface soils found in riparian areas to temporarily block nitrous oxide reductase in denitrifying bacteria. Accomplishing this would allow use of the acetylene block method for denitrification rate assessment in the soils of riparian areas that are periodically saturated and with high potential for large denitrificafion rates. Method development and testing was conducted in the laboratory, using a 1.4 m3 mesocosm filled with sandy subsoil with continuous forced‐gradient radial flow. Movement of Br tracer and C2H2 injected into a central well was monitored by sampling from 25 and 50 cm distant radial wells. Both the tracer and aqueous C2H2 showed relatively uniform flow rates to the 25 cm wells, and then varied by a factor of two to the 50 cm wells. Acetylene concentrations exceeded those recommended to block NOx reduction by denitrifiers at the N2O stage. In situ denitrification rates were derived from monitored N2O concentrations. An initial field test provided additional evidence that the procedure may be useful for direct measurement of denitrification losses in a variety of natural, shallow groundwater systems.
Phosphorus Transformations in the Sediments of Delaware's Agricultural Drainageways: I. Phosphorus Forms and Sorption
Authors: Sallade Y. E. , Sims J. T.
Published: July 2010

Many soils in Delaware's Inland Bays' watershed are high in phosphorus (P) from long‐ term manuring and fertilization and require artificial drainage (open ditches) for successful crop production. We characterized the properties, forms of P, and P sorption capacity of sediments from 17 drainage ditches as part of an ongoing effort to develop best management practices for agricultural drainage. Upper sediment layers (0–5 cm depth) were enriched in organic matter, Fe/Al oxides, soil test (Mehlich 1‐P; 0.05 N HCl + 0.025 N H2SO4) P and biologically available P (BAP) relative to lower sediment depths (5–15 cm) and to agricultural subsoils at the same depth as the ditch bottoms. Sediment BAP was comparable to values for topsoils in adjacent fields and >90% of sediment P was NH4F‐P or NaOH‐P. The P sorption capacity for top sediments ranged from 95 to 1671 mg P kg−1 and equilibrium P concentrations at zero sorption (EPC0) from 0.02 to 0.28 mg P L−1, consistently above P concentrations associated with fresh water eutrophication (0.02 mg P L−1). Soluble P concentrations in drainage ditch waters averaged 0.05, 0.06, and 0.15 mg P L−1 in the winter, spring, and summer. Sediment BAP (0–5 cm) could be predicted from Mehlich 1‐P and %OM (R2 = 0.80***) and P sorption capacity from a single point P sorption index (PSI) and %OM (R2 = 0.81”**) suggesting routine soil tests could help identify ditches with significant potential for nonpoint source pollution of surface waters.
Calcium Sulfate as a Flocculant to Reduce Sedimentation Basin Water Turbidity
Authors: Przepiora A. , Hesterberg D. , Parsons J. E. , Gilliam J. W. , Cassel D. K. , Faircloth W.
Published: July 2010

A high‐suspended solids load in surface waters is one of the biggest water quality problems in the Piedmont region of the southeastern USA. Sedimentation basins at construction sites are designed to reduce suspended solids in discharged water, but they are not effective in reducing turbidity. A survey of sedimentation basin water at two urban construction sites showed that turbidity levels during a 9‐ to 12‐mo period were always greater than the 50‐NTU (nephelometric turbidity units) standard adopted in North Carolina for surface waters. Furthermore, water chemistry varied over time, with pH ranging from 5.8 to 8.9 and electrical conductivity (EC) ranging from 3.0 to 23.0 mS m−1. Laboratory experiments demonstrated that temporal variations in the water chemistry were likely caused by contact with concrete and crushed stone. Laboratory flocculation experiments were completed to evaluate the efficiency of calcium sulfate compounds (hemihydrate, agricultural gypsum, and phosphogypsum) as chemical flocculants for reducing the turbidity of sedimentation basin water from two field sites and for different pH conditions. Moulding plaster (hemihydrate) was a more efficient flocculant than agricultural gypsum and has fewer environmental restrictions on its use than phosphogypsum. Moulding plaster application rates of 350 to 700 mg L−1 were needed to reduce the turbidity of unstirred sedimentation basin water to 50 NTU within 3 h after addition of the flocculant. To achieve a given turbidity level, less flocculant was required for longer flocculation and settling times, or when sedimentation basin water had a lower pH.
Herbicide Contamination of Groundwater Beneath Claypan Soils in North‐Central Missouri
Authors: Blanchard P. E. , Donald W. W.
Published: July 2010

The impact of hydrology and site‐specific soil stratigraphy on herbicide leaching are not well understood for claypan soils. The claypan is a naturally‐occurring argillic soil horizon that limits percolation to groundwater. The primary objective of this study was to determine the extent of nonpoint source herbicide contamination of shallow groundwater beneath claypan soils. The secondary objective was to determine the relative importance of hydrology and land management to observed herbicide contamination of groundwater during a 5‐year period. The study site was the 7250 ha Goodwater Creek Watershed in north‐central Missouri. Three cropped fields with 10 yr of similar management were instrumented with 20 to 25 monitor wells each in 1991. The three fields were treated with different rates of atrazine [2‐chloro‐(4‐ethylamino)‐6‐(isopropylamino)‐s‐triazine] and alachlor [2‐chloro‐2′, 6′‐diethyl‐N‐(methoxymethyl)acetanilide] and the wells were sampled quarterly from 1991 to 1996. Atrazine was detected in 7.2% of samples, with a maximum concentration of 0.12 µg L−1 (limit of detection, LOD = 0.02 µg L−1). Alachlor was detected in 0.4% of samples with a maximum concentration of 0.14 µg L−1 (LOD = 0.11 µg L−1). Site to site variability in hydrology was more important than differences in herbicide application rates, as the field treated with the least atrazine and alachlor had the most frequent detections of atrazine, the atrazine metabolite deethylatrazine [2‐chloro‐(4‐amino)‐6‐(isopropylamino)‐s‐triazine; DEA], and the alachlor metabolite [2‐[(2,6‐diethylphenyl) (methoxymethyl)amino]‐2‐oxoethanesulfonic acid; ESA]. Groundwater recharge occurred primarily during the nongrowing season. Therefore, herbicide and metabolite leaching were limited by the extent of their degradation in the soil during the growing season. The study results demonstrate the importance of hydrologic variability, recharge timing, and chemical properties with respect to the leaching of herbicides and herbicide metabolites.
Comparative Effects of Poultry and Swine Waste Lagoon Spills on the Quality of Receiving Streamwaters
Authors: Mallin Michael A. , Burkholder JoAnn M. , McIver Matthew R. , Shank G. Christopher , Glasgow Howard B. , Touchette Brant W. , Springer Jeffrey
Published: July 2010

During July 1995, a poultry waste lagoon ruptured in Duplin County, North Carolina, sending 32.6 million L of chicken waste effluent into a nearby creek and the Northeast Cape Fear River. In August 1995 a breach of a hog waste lagoon released approximately 7.6 million L of waste into a system of blackwater creeks in Brunswick County, North Carolina. The poultry waste spill occurred under high rainfall‐high river flow conditions, while the swine waste lagoon spill occurred during dry conditions. Both spills caused high turbidity and low dissolved oxygen (DO) in receiving waters, and DO levels in the Northeast Cape Fear River displayed a “sag curve” 10 d after the poultry waste spill, reaching a minimum of 1.0 mg L−1 90 km downstream. Both spills delivered high N loads to receiving waters (maxima of 92.1 mg L−1 from the poultry spill and 47.0 mg L−1 from the swine waste spill). Phosphorous concentrations reached 6.0 and 11.5 mg L−1 in receiving waters of the poultry and swine waste spills, respectively. Dense phytoplankton blooms (>100 µg chlorophyll a L−1) were measured in the blackwater creeks after the swine spill. High fecal coliform concentrations were delivered by both spills, and concentrations of the pathogenic bacterium Clostridium perfringens ranged up to 40 000 colony‐forming units (CFU) mL−1 in the receiving waters after the poultry spill. In 1995 and 1996 more than 30 animal waste lagoon breaches, overtoppings, and inundations were reported in North Carolina, demonstrating the major pollution potential of these treatment systems.
Cadmium in Australian Potato Tubers and Soils
Authors: McLaughlin M. J. , Maier N. A. , Rayment G. E. , Sparrow L. A. , Berg G. , McKay A. , Milham P. , Merry R. H. , Smart M. K.
Published: July 2010

Cadmium (Cd) has been identified as a potential contaminant in foods posing health risks to humans and, in Australia, potatoes (Solanum tuberosum L.) have been identified as contributing a large proportion of the average dietary Cd intake. To assess the concentrations of Cd in Australian potatoes and soil factors likely to lead to high Cd concentrations, commercial crops and soils were sampled at 352 sites throughout potato production areas in Australia. Across all states, fresh weight (FW) tuber Cd concentrations ranged from 0.004 to 0.232 mg kg−1 with an overall mean value of 0.041 and a median of 0.033 mg kg−1 (FW). Approximately 92 samples out of 359 (25.6%) exceeded the current maximum permitted concentration (MPC) of 0.05 mg kg−1 (FW) and 18 (5.0%) exceeded 0.1 mg kg−1 (FW). Concentrations of Cd (EDTA‐extractable) in topsoils ranged from 0.01 to 0.59 mg kg−1 with mean and median values of 0.14 and 0.10 mg kg−1, respectively. There was no relationship between Cd concentrations in soil and tubers. Stepwise forward multiple regression analysis of the data indicated that Cl and Zn concentrations in the topsoil, soil pH, and potato cultivar accounted for 57% of the variation in tuber Cd concentrations, with Cl being the dominant factor. Comparison of soil‐plant transfer coefficients (TCs) for Cd with limited international data sets suggests that TCs for Australian soils used for potato production are relatively high.
Mineralizable Nitrogen in Broiler Litter: I. Effect of Selected Litter Chemical Characteristics
Authors: Gordillo R. M. , Cabrera M. L.
Published: July 2010

Broiler (chicken, Gallus gallus domesticus) litter is a mixture of manure and bedding material that is generated in large amounts by the broiler industry. This litter is typically applied to land as fertilizer, at rates estimated to supply adequate N. Estimation of rates is currently hampered by the lack of rapid methods to determine mineralizable N in BL. This study was conducted to compare the kinetics of N mineralization of 15 BL samples, and to evaluate selected chemical characteristics of the litter as predictors of mineralizable N. Broiler litter samples were mixed with samples of Cowarts soil (150 mg organic N kg−1 soil, −0.02 MPa) and incubated at 25°C for 112 d. Cumulative net N mineralized was fitted to a two‐pool, first‐order model, to determine the size of fast and slow pools of mineralizable N. The fast N pool varied from 116 to 569 g N kg−1 organic N (ON), and could be predicted from uric acid‐N concentration in the litter (R2 = 0.92). The size of the slow N pool did not vary significantly among BL samples; (309 ± 94 g N kg−1 ON). Total mineralizable N (fast + slow N pools) ranged from 465 to 868 g N kg−1 ON, and could be predicted from uric acid‐N and total N concentrations (R2 = 0.91), or from uric acid‐N concentration and C/N of the litter (R2 = 0.95). The simplicity of the chemical indices involved should make this approach attractive to estimate mineralizable N in BL.
Evaluation of Nitrate Leaching Potential in Minnesota Glacial Outwash Soils using the CERES‐Maize Model
Authors: Pang X. P. , Gupta S. C. , Moncrief J. F. , Rosen C. J. , Cheng H. H.
Published: July 2010

This study examined how the CERES‐Maize model could be used to identify N and irrigation management practices that minimize nitrate leaching as well as provide economical corn (Zea mays L.) yield in glacial outwash soils of Minnesota. The model was validated against 2 yr of experimental data on corn grain yield, N uptake, and nitrate leaching for control and three N fertilizer application rates under two irrigation schedules on a sandy loam soil at Staples, MN. Simulated values were close to the measured corn yield, and were within the range of differences for similar comparisons. Simulations using 31 yr of climatic data showed that an irrigation trigger deficit as low as 30% had little impact on corn yield but significant impact on reduced percolation and nitrate leaching. A procedure was developed to characterize the potential of nitrate leaching in outwash soils using the output from the CERES‐Maize model. We used this procedure to characterize nitrate leaching from soils in Wadena County, MN. As expected, the high risk soils had the lowest water holding capacity and the highest drainage coefficient. The factors affecting the risk of nitrate leaching are: irrigation schedule > climatic variability = N application rate. Linking a validated simulation model with a soil survey data base provides a valuable tool in site specific assessment and prescription of best irrigation and N management practices for the glacial outwash soils of the North Central region.
Fecal Coliform Transport through Intact Soil Blocks Amended with Poultry Manure
Authors: McMurry S. W. , Coyne M. S. , Perfect E.
Published: July 2010

Poultry production in Kentucky increased almost 200% between 1991 and 1995. Their waste is typically land applied, and fecal pathogen runoff and infiltration may cause nonpoint source groundwater pollution. We looked at the preferential flow of fecal coliforms through undisturbed soil blocks since fecal bacteria typically infiltrate the soil profile to contaminate groundwater. Poultry manure was uniformly distributed on top of sod‐covered or tilled (upper 12.5 cm) soil blocks and the blocks were irrigated. Drainage was collected in 100 uniformly spaced cells beneath each block and analyzed for fecal coliform content and drainage volume. The spatial distribution of drainage and fecal coliforms through the soil blocks was not uniform. Fecal coliforms appeared where most drainage flowed. Drainage water from each soil block consistently exceeded 200 000 fecal coliforms per 100 mL and was as great as 30 million fecal coliforms per 100 mL of leachate collected. Fecal coliforms leached as a pulse, but the breakthrough of fecal coliforms through tilled blocks was delayed with respect to the breakthrough of fecal coliforms through sod‐covered blocks. Rainfall on a well‐structured soil will cause the preferential movement of fecal bacteria, even with unsaturated flow conditions, and could contribute to fecal coliform concentrations in shallow groundwater that exceed standards for domestic discharge and primary contact water in Kentucky (200 fecal coliforms/100 mL).
Decreasing Metal Runoff from Poultry Litter with Aluminum Sulfate
Authors: Moore P. A. , Daniel T. C. , Gilmour J. T. , Shreve B. R. , Edwards D. R. , Wood B. H.
Published: July 2010

Aluminum sulfate [Al2(SO4)3·14H2O] applications to poultry litter can greatly reduce P concentrations in runoff from fields fertilized with poultry litter, as well as decrease NH3 volatilization. The objective of this study was to evaluate metal runoff from plots fertilized with varying rates of alum‐treated and untreated (normal) poultry litter. Alum‐treated (10% alum by weight) and untreated litter was broadcast applied to small plots in tall fescue (Festuca arundinacea Schreb.). Litter application rates were 0, 2.24, 4.49, 6.73, and 8.98 Mg ha−1 (0, 1, 2, 3, and 4 tons acre−1). Rainfall simulators were used to produce two runoff events, immediately after litter application and 7 d later. Both concentrations and loads of water‐soluble metals increased linearly with litter application rates, regardless of litter type. Alum treatment reduced concentrations of As, Cu, Fe, and Zn, relative to untreated litter, whereas it increased Ca and Mg. Copper concentrations in runoff water from untreated litter were extremely high (up to 1 mg Cu L−1), indicating a potential water quality problem. Soluble Al, K, and Na concentrations were not significantly affected by the type of litter. Reductions in trace metal runoff due to alum appeared to be related to the concentration of soluble organic C (SOC), as well as the affinity of SOC for trace metals. Metal runoff from alum‐treated litter is less likely to cause environmental problems than untreated litter, since threats to the aquatic environment by Ca and Mg are far less than those posed by As, Cu, and Zn.
Reducing Soil Phosphorus Solubility with Coal Combustion By‐Products
Authors: Stout William L. , Sharpley Andrew N. , Pionke Harry B.
Published: July 2010

In the northeast USA, most soil samples analyzed for soil test P (STP) in 1990 exceeded P levels needed for plant production. Converting soil P to less soluble forms with applications of materials containing lime or Ca may reduce the release of soil P to runoff. We investigated the effect of several coal combustion by‐products on STP (Bray‐1 and Mehlich‐III), water extractable P, and equilibrium P concentration (EPC0) of high P soils. Three widely available by‐products were used: fluidized bed combustion fly ash (FBC), flue gas desulfurization by‐product (FGD), and pulverized coal flyash (PC). In a by‐product type and rate experiment, a Berks soil with high STP was incubated for 21 d with each by‐product (0, 10, 20, 40, and 80 g kg soil−1). The highest rates of FBC and FGD reduced Mehlich‐III P (45%), Bray‐I P (50%), water extractable P (72%) and EPC0 (37%). The PC had no effect on soil P solubility due to the addition of P with this by‐product. For eight soils ranging in physical and chemical properties, FBC at 10 g kg soil−1 reduced Mehlich‐III P 13%, and water‐extractable P 71%, while FGD reduced Mehlich‐III P 8% and water‐extractable P 48%. These reductions resulted from the conversion of readily desorbable soil P to less soluble Ca‐bound or Al‐ and Fe‐bound pools. Amending high P soils with FBC or FGD by‐products has the potential to reduce P enrichment of runoff by decreasing the solubility of soil P without reducing STP below optimum levels for plant growth.
Land Use and Soil Nitrogen Status in a Tropical Pacific Island Environment
Authors: Motavalli P. P. , McConnell J.
Published: July 2010

The rapid rate of land development in the Micronesian Region of the Pacific Ocean has raised public concern over the effects of land disturbance and land use on potential NO−3 pollution and other longterm impacts on soil properties. Our objective was to compare the soil N status and other soil chemical and physical properties of several land use sites on Guam, including an area under secondary forest vegetation, an area under continuous cultivation, an area recently cleared for agriculture, and an abandoned agricultural area. Continuous agricultural cultivation over a 7‐yr period increased soil bulk density and soil pH and lowered water‐holding capacity, organic C, total N, and N mineralization compared with soil in a forested site. Soil organic N fractions, including microbial biomass N and particulate organic matter N, were reduced by the mixing effects of tillage in the cultivated site. Initial clearing of vegetation increased bulk density and pH but did not decrease soil organic C and N compared with the forest site. Soil at an agricultural site that had been abandoned for an 11‐yr period did not return to levels of organic C, total N, and N mineralization observed in the forest and cleared sites. These results suggest that long‐term tillage has a significant impact on soil properties in this tropical island environment, including reducing active and stable N pools. However, the significance of these changes on NO−3 leaching is unclear because of alterations in soil properties affecting both soil water movement and other N processes.