bluuebunny/crossref_metadata_2025 huggingface dataset:
Alkaline Phosphatase Activity in the Sediment‐Water Column of a Hypereutrophic Lake
Authors: Newman S. , Reddy K. R.
Published: July 2010

Inorganic P limitation in many aquatic systems may be overcome through the enzymatic hydrolysis of organic P compounds. The objective of our study was to determine the effect of dissolved oxygen (DO) of the water column and redox (Eh) status of the sediments on alkaline phosphatase activity (APA) in a shallow hypereutrophic lake located in central Florida. Alkaline phosphatase activity was used as an index of potential organic P mineralization. Lake water was incubated in the dark under aerobic and anaerobic conditions for 24 h. Under aerobic conditions APA increased from 22 to 43 nM min−1 within 24 h. Under anaerobic conditions no significant change in APA was observed. Neither total soluble P nor soluble‐reactive P exhibited significant responses to anoxic conditions in the water column. The increase in APA observed under aerobic conditions was attributed to increased plankton metabolic P demand following depletion of internal cell P. Sediments were incubated under six different Eh levels for 30 d. In combination with APA measurements, sediment organic P was fractionated into labile and nonlabile pools using selected inorganic chemical extractants. Phosphatase hydrolysis of organic P was significantly inhibited under anaerobic conditions. Alkaline phosphatase activity was positively related to pE + pH (r = 0.90). Conversely, porewater organic P was inversely correlated with pE + pH (r = −0.92). Alkaline phosphatase activity was also inversely related to porewater organic P (r = −0.95), labile organic P (r = −0.81), and humic acid P (r = −0.74). The results of this study suggest that short‐term depletion of DO will not affect the enzymatic breakdown of organic P within the water column. Significant reduction in the alkaline phosphatase‐dependent hydrolysis of sedimentary organic P will occur under anaerobic conditions; hence, P cycling in highly organic sediments may be severely inhibited.
Soil Nitrate Leaching Potential Indices: Using a Simulation Model as a Screening System
Authors: Khakural B. R. , Robert P. C.
Published: July 2010

Simulation models LEACHM‐N (Leaching Estimation and Chemistry Model) and NLEAP (Nitrate Leaching and Economic Analysis Package) were first tested using NO3 leaching data obtained from lysimeter and tile drainage studies conducted at three University of Minnesota experiment stations. Both simulation models did well in simulating total (seasonally accumulated) leaching loss of NO3‐N from the soil profile. LEACHM‐N was selected as a screening tool to develop soil NO3 leaching potential (NLP) ratings using soil survey information and representative county weather station data. Simulated growing season total NO3‐N leached from the soil profile (below 1.5 m) were used as NLP index. Crop management practices and initial N were kept constant. Soil NO3 leaching potential ratings for three Minnesota counties, Redwood, Stearns, and Sherburne were developed using this method. This soil NLP rating information was included in the Soil Survey Information System (SSIS) to create leaching potential rating maps, which can be used to plan best N management schemes.
The Determination of Total Dissolved Inorganic Carbon in Aqueous Solutions
Authors: Frisbie Seth H. , Bouldin David R.
Published: July 2010

Experimental results and theoretical considerations were utilized to develop a method for the precise and accurate determination of total dissolved inorganic carbon (TDIC) in aqueous solutions. A method of preparing standard solutions of Cs2CO3 from distilled deionized H2O which was initially stripped of ambient inorganic carbon (IC) with N2(g) at 6.90 × 104 Pa for 20 min allowed a means of calibration without systematic error. For a 0.20‐mL sample, a quadratic working range of analysis extended from the limit of detection, 1.05 × 10−5M IC, to 3.44 × 10−3 M IC. Results are accurate to three significant figures. The smallest R2 observed over 4 yr was 0.997. For 0.05‐, 0.10‐, and 0.20‐mL sample volumes, no significant effect of solution volume on detector response was observed. In order to expedite routine analysis, a means of preparing and storing secondary standard solutions of NaHCO3 for up to 28 d was developed.
Recycling of Cattle Manure: The Composting Process and Characterization of Maturity
Authors: Inbar Yossi , Hadar Yitzhak , Chen Yona
Published: July 2010

The utilization of cattle (Bos sp.) manure as a peat substitute in greenhouses has been proposed. This alternative requires certain preparatory procedures, including composting. The objective of this research was to study the composting process, changes occurring in the product during composting and product properties of relevance to its potential use as a container medium, and to evaluate possible criteria indicating compost maturity. Composting of separated cattle manure (CSM) was studied in 1‐m3 perforated boxes. Most of the physical and some of the chemical properties exhibited a high rate of change during the first 40 to 60 d of the composting process. Total water‐soluble salts, as measured by electrical conductivity (EC), exhibited a constant value for the first 60 d, followed by a sharp increase in EC (from 2.6–5.4 dS m−1). The main ions contributing to this increase were NO−3, Ca2+ and Mg2+. As temperature decreased, nitrate levels increased sharply due to nitrification, from 0.02 cmol L−1 at the beginning to 4.0 cmol L−1 at the end of the composting process. Although most changes took place during the first high temperature phase, slow decomposition persisted after temperature returned to ambient level as measured in the compost water extract. Plant bioassays also indicated that 40‐ to 60‐d old compost inhibited growth and there was limited response to fertilization. Both of these factors were eliminated after 80 to 90 d of composting. Chemical properties of water extracts may therefore serve as indicators of compost maturity and of the material's suitability as an organic component for container media.
Minimizing Agricultural Nonpoint‐Source Impacts: A Symposium Overview
Authors: Sharpley Andrew , Meyer Mike
Published: July 2010

Increased public awareness of the role of agriculture and associated chemical use in nonpoint‐source pollution has prompted an urgency in obtaining information on the impact of current and proposed agricultural management practices on water quality. Because of easier identification and control of point sources of pollution, agricultural nonpoint sources now account for a larger share of all discharges than a decade ago. Consequently, there is a need to identify critical sources for control; target specific controls for different water quality objectives within different watersheds; and evaluate and implement cost‐effective management practices that minimize the potential loss of agricultural chemicals to surface and groundwaters. This paper provides a brief overview of agricultural nonpoint‐source issues and options presented at a special symposium, “Minimizing Agricultural Nonpoint‐Source Impacts,” held during the American Society of Agronomy meetings in November 1992 and cosponsored by the Metropolitan Waste Control Commission. Several papers that were given at this symposium and presented in this issue are introduced.
Interlaboratory Comparison of Iron Oxide‐Impregnated Paper to Estimate Bioavailable Phosphorus
Authors: Sharpley A. N. , Indiati R. , Ciavatta C. , Rossi N. , Sequi P.
Published: July 2010

The transport of bioavailable phosphorus (BAP) in agricultural runoff can accelerate the eutrophication of receiving water bodies. However, procedural and theoretical limitations of algal bioassays and chemical extractants have restricted widespread measurement of BAP. Thus, a simple method using iron oxide—impregnated paper (Fe‐oxide strips) as a sink for BAP in runoff samples has been developed. As the method has potential application for BAP extraction at one location and analysis at another, Fe‐oxide strips were sent to Bologna and Rome, Italy, for P extraction of runoff samples and BAP determined. These BAP estimates were not significantly different (p < 0.001) from values determined on duplicate strips returned to the USA for BAP analysis. The close agreement in BAP measured in Italian and U.S. laboratories indicates that the simplicity of the proposed method can give highly reproducible BAP estimates. Prepared Fe‐oxide strips may be sent to a location and BAP extracted using only a 100‐ to 500‐mL bottle in which a strip and runoff sample are shaken overnight. The Fe‐oxide strip may then be air‐dried and returned to an analytical laboratory for subsequent P removal and measurement. Storage of these strips for up to 60 d had no effect on the amounts of P released.
Evaluating Agricultural Nonpoint‐Source Pollution Using Integrated Geographic Information Systems and Hydrologic/Water Quality Model
Authors: Tim Udoyara S. , Jolly Robert
Published: July 2010

Considerable progress has been made in developing physically based, distributed parameter, hydrologic/water quality (H/WQ) models for planning and control of nonpoint‐source pollution. The widespread use of these models is often constrained by the excessive and time‐consuming input data demands and the lack of computing efficiencies necessary for iterative simulation of alternative management strategies. Recent developments in geographic information systems (GIS) provide techniques for handling large amounts of spatial data for modeling nonpoint‐source pollution problems. Because a GIS can be used to combine information from several sources to form an array of model input data and to examine any combinations of spatial input/output data, it represents a highly effective tool for H/WQ modeling. This paper describes the integration of a distributed‐parameter model (AGNPS) with a GIS (ARC/INFO) to examine nonpoint sources of pollution in an agricultural watershed. The ARC/INFO GIS provided the tools to generate and spatially organize the disparate data to support modeling, while the AGNPS model was used to predict several water quality variables including soil erosion and sedimentation within a watershed. The integrated system was used to evaluate the effectiveness of several alternative management strategies in reducing sediment pollution in a 417‐ha watershed located in southern Iowa. The implementation of vegetative filter strips and contour buffer (grass) strips resulted in a 41 and 47% reduction in sediment yield at the watershed outlet, respectively. In addition, when the integrated system was used, the combination of the above management strategies resulted in a 71% reduction in sediment yield. In general, the study demonstrated the utility of integrating a simulation model with GIS for nonpoint‐source pollution control and planning. Such techniques can help characterize the diffuse sources of pollution at the landscape level.
Importance of Soil and Cropping Systems in the Development of Regional Water Quality Policies
Authors: Geleta S. , Sabbagh G. J. , Stone J. F. , Elliott R. L. , Mapp H. P. , Bernardo D. J. , Watkins K. B.
Published: July 2010

Targeting certain soils and cropping systems may be necessary in consideration of regional water quality protection policies. However, little information is available relating soils and cropping practices to regional water quality problems. This study evaluates crop yield and NO3‐N movement to surface and groundwater on four soils and nine principal cropping systems in the High Plains region of Oklahoma. The cropping systems involve wheat (Triticum aestivum L.), grain sorghum [Sorghum bicolor (L.) Moench], and corn (Zea mays L.), and are part of a regional data base also containing soils and chemical management information. For each combination of crop, soil, cropping system, and chemical alternative, a 20‐yr simulation was made. The simulation was based on a modeling system that includes EPIC‐PST (crop growth/chemical movement model) interfaced with a Geographic Information System (GIS), Earthone. Results of each simulation included crop yield and NO3‐N movement in runoff and percolation. Results show wide variations in NO3‐N losses for different soils, irrigation systems, and cropping systems. When compared with continuous irrigated wheat and grain sorghum cropping systems, double‐cropped wheat‐grain sorghum resulted in greater NO3‐N loss in percolation. Compared with sprinkler and LEPA (low energy precision application) irrigation systems, furrow irrigation resulted in high NO3‐N loss on both fine‐textured and coarse‐textured soils, with significantly greater loss on the coarser‐textured soils. The modeling framework can be used to compare alternative water quality policies. Broad policies such as a restriction on the amount of N that can be applied per hectare can be compared with targeted policies, such as limiting N applications or irrigation water use on coarser soils or under furrow irrigation.
Effect of Drying and Rainfall Intensity on Cyromazine Loss from Surface‐Applied Caged‐Layer Manure
Authors: Pote D. H. , Daniel T. C. , Edwards D. R. , Mattice J. D. , Wickliff D. B.
Published: July 2010

Most poultry manure is surface‐applied as pasture fertilizer. Cyromazine (N‐cyclopropyl‐1,3,5‐triazine‐2,4,6‐triamine), a feed through larvicide used to control house flies (Musca domestica), is often a manure component in caged‐layer (Gallus gallus domesticus) systems. Since cyromazine is quite soluble and stable in water, the objective of this study was to quantify cyromazine in runoff and soil water from pasture treated with caged‐layer manure. Plots of uniform slope were bordered to isolate runoff and planted in fescue (Festuca arundinacea Schreb). Manure was analyzed for cyromazine content and applied at 0, 4.4, and 17.7 Mg ha−1 (dry basis). Rain was applied by simulator at 50 and 100 mm h−1. Runoff was analyzed for cyromazine and its metabolite, melamine (1,3,5‐triazine‐2,4,6‐triamine). A high manure application rate increased runoff volume and cyromazine concentration. High rain intensity increased total cyromazine runoff loss but provided enough runoff volume to reduce the concentration. Mean cyromazine concentration in runoff was as high as 101 µg L−1, and mean cyromazine loss was as high as 23.7%. Pan lysimeters monitored soil water in the vadose zone for 1 yr after the manure application, but cyromazine and melamine were not detected. In a follow‐up study, plots received manure at 3.76 Mg ha−1, were allowed to dry for either 1 or 7 d, and then received rain at 50 mm h−1 for 30 min of runoff. The 7‐d drying time decreased cyromazine loss, apparently by reducing both runoff volume and cyromazine concentration in the runoff.
Phosphorus in Drainage Water from Sugarcane in the Everglades Agricultural Area as Affected by Drainage Rate
Authors: Coale F. J. , Izuno F. T. , Bottcher A. B.
Published: July 2010

Sugarcane (interspecific hybrids of Saccharum spp.) is grown on 78% (156,000 ha) of the cultivated organic soils of the Everglades Agricultural Area (EAA) of southern Florida. Recently, the EAA has come under scrutiny because of concerns with the impact of nutrient‐rich drainage water from organic soils on the ecology of adjoining bodies of water and wetlands. The objectives of our research were to determine the effects of field drainage rate on P concentration and off‐field P loads in drainage water from sugarcane grown on organic soils of the EAA and to determine the effect of field drainage rate on sugarcane productivity and sugar yield. The research site was on a Terra Ceia muck soil (euic, hyperthermic Typic Medisaprist) on a commercial sugarcane farm located in the EAA. The treatments were fast and slow field drainage rates. Nine drainage events were monitored between Nov. 1988 and Aug. 1990. Average drainage water total P (TP) and total dissolved P (TDP) concentrations were significantly higher for the slow drainage rate treatment. In order to minimize off‐farm P loading, main‐farm canal water should be discharged off‐farm while field drainage water is retained on‐farm. Field drainage rate should be fast and drainage event duration should be as short as possible. Plant‐cane crop yield and yield component data were not collected. The first‐ratoon crop total aerial dry weight and harvested sugarcane and sugar yields were not affected by drainage rate.
Nitrogen Accumulation and Form over Time in Young Mine Soils
Authors: Li R. S. , Daniels W. L.
Published: July 2010

Nitrogen deficiency is a common problem during reclamation of mine soils, and limited comprehensive information is available concerning the forms and characteristics of N in Appalachian mine soils. This chronosequence study was conducted to investigate the accumulation, distribution, and component change of N in mine soils over time. Fresh spoil, coal, natural forest soil and 10 mine soil sites with ages ranging from 1 to 30 yr were sampled and analyzed for N components. Young mine soils (> 10 yr) were dominated by seeded grass‐legume vegetation, while the older sites supported native mixed hardwoods. There was a considerable amount of indigenous N in the fresh spoils (250–475 mg kg−1), consisting primarily of fixed NH+4 (Fix‐N) held in micas and nonhydrolyzable organic N (NoHyOM‐N) bound in coal. Both the Fix‐N and NoHyOM‐N fractions were geologic N, stable in chemical character, and unavailable to plants. With time, N accumulation occurred primarily in the surface 0 to 5 cm, associated with A horizon development. In this layer, soil total N and active N [Act‐N, consisting of hydrolyzable organic N (HyOM‐N) and exchangeable N (Exch‐N)], were significantly correlated with site age. The corrected‐N (Corr‐N), which was obtained by subtraction of soil total N at 10 to 20 cm from soil total N at 0 to 5 cm at each site, had a much higher correlation coefficient with site age (r = 0.95, P < 0.0001) due to its correction for variation in soil indigenous N content among sites. The annual rate of N accumulation estimated by the Corr‐N method was 60.5 mg N kg−1 in soil (<2mm) or 23.4 kg N ha−1 in the top 0 to 5 cm. The total C content of the mine soils was correlated with site age (r = 0.65, P < 0.05), while pH, N availability index, Fix‐N, and NoHyOM‐N were not.
Trace Metal Solubility in Soils and Waters Receiving Deicing Salts
Authors: Amrhein C. , Mosher P. A. , Strong J. E. , Pacheco P. G.
Published: July 2010

Laboratory batch incubation studies were carried out to determine the effects of aerobic and anaerobic conditions on the solubility of trace metals in soils and waters treated with the deicing salts calcium magnesium acetate (CMA) and NaCl. The concentrations of trace metals were, in general, not controlled by equilibrium reactions but rather by the relative rates of several simultaneous and sequential reactions. In three soils from CA, NJ, and MI, and water treated with CMA the production of HCO3 from acetate decomposition initially increased the solution concentration of Pb and Zn as PbCO03 and ZnCO03. Eventually, supersaturation with respect to calcite occurred and the concentrations ofCu, Cd, Zn, V, and Cr decreased because of coprecipitation with the calcite. The precipitation of pyromorphite [Pb5(PO4)3Cl] was suspected based on elevated saturation indexes for this mineral. At low redox conditions, the solubilization of Fe‐ and Mn‐oxides increased the concentration of the trace metals that were adsorbed or coprecipitated with these phases. Supersaturation with respect to MnCO3, FeCO3, and VO(OH)2 occurred under low redox conditions. The rate constant for acetate decomposition under anaerobic conditions was 18 times lower than the rate constant for aerobic decomposition. This suggests that if a soil received a high loading of CMA, low O2 conditions could occur and CMA might leach to groundwater. There is evidence that the use of CMA could result in Pb and Zn mobilization as neutral ion pairs with carbonate.
Leaching of Nitrogen and Phosphorus from the Biomass of Three Cover Crop Species
Authors: Miller M. H. , Beauchamp E. G. , Lauzon J. D.
Published: July 2010

Cover crops, although they may reduce the leaching of NO3‐N to groundwater, may increase nutrient concentration in runoff because of biomass leaching during rainfall events. A simulated rainfall study was conducted in the laboratory to determine the effects of freezing alone and freezing plus drying treatments, loading rate, and rainfall intensity on the leaching of NH4‐N, NO3‐N, and inorganic P from the biomass of red clover (Trifolium pratense L.), annual ryegrass (Lolium multiflorum L.), and oilseed radish [Raphanus sativus (L.) var. oleifera Dc Metzg]. Concentration of P increased during early stages of leaching, then decreased slowly but remained greater than 50% of the maximum, even after the equivalent of 6.0 cm of simulated rainfall. Concentrations of NO3‐N were similar to P but changed less during leaching. Weighted mean concentrations of P ranged from less than 2.0 to more than 15 mg L−1. Concentrations were greatest with oilseed radish and least with red clover. Drying the sample in addition to freezing increased the P concentration, particularly in the initial leaching. About 30% of the biomass P was leached from oilseed radish and annual ryegrass, but only about 20% from red clover. Because oilseed radish had a greater biomass P concentration, the total P leached was much greater than for the other two species. Between 5 and 9% of the biomass N was leached as either NO3‐N or NH4‐N from ryegrass and red clover while over 10% was leached from oilseed radish. The results indicate that cover crop species differed markedly in their potential impact on nutrient concentration, particularly P, in runoff. Of the three cover crops tested, oilseed radish has the greatest potential impact and red clover the least.
Hycrest Crested Wheatgrass Accelerates the Degradation of Pentachlorophenol in Soil
Authors: Ferro Ari M. , Sims Ronald C. , Bugbee Bruce
Published: July 2010

We investigated the effects of vegetation on the fate of pentachlorophenol (PCP) in soil using a novel high‐flow sealed test system. Pentachlorophenol has been widely used as a wood preservative, and this highly toxic biocide contaminates soil and ground water at many sites. Although plants are known to accelerate the rates of degradation of certain soil contaminants, this approach has not been thoroughly investigated for PCP. The fate of [14C]PCP, added to soil at a concentration of 100 mg/kg, was compared in three unplanted and three planted systems. The plant used was Hycrest, a perennial, drought‐tolerant cultivar of crested wheatgrass [Agropyron desertorum (Fischer ex Link) Schultes]. The flow‐through test system allowed us to maintain a budget for 14C‐label as well as monitor mineralization (breakdown to 14CO2) and volatilization of the test compound in a 155‐d trial. In the implanted systems, an average of 88% of the total radiolabel remained in the soil and leachate and only 6% was mineralized. In the planted systems, 33% of the radiolabel remained in the soil plus leachate, 22% was mineralized, and 36% was associated with plant tissue (21% with the root fraction and 15% with shoots). Mineralization rates were 23.1 mg PCP mineralized kg−1 soil in 20 wk in the planted system, and for the implanted system 6.6 mg PCP kg−1 soil for the same time period. Similar amounts of volatile organic material were generated in the two systems (1.5%). Results indicated that establishing crested wheatgrass on PCP‐contaminated surface soils may accelerate the removal of the contaminant.
Occurrence of Atrazine and Degradates as Contaminants of Subsurface Drainage and Shallow Groundwater
Authors: Jayachandran K. , Steinheimer T. R. , Somasundaram L. , Moorman T. B. , Kanwar R. S. , Coats J. R.
Published: July 2010

Atrazine is a commonly used herbicide in corn (Zea mays L.) growing areas of the USA. Because of its heavy usage, moderate persistence, and mobility in soil, monitoring of atrazine movement under field conditions is essential to assess its potential to contaminate groundwater. Concentrations of atrazine, deisopropylatrazine (DIA), and deethylatrazine (DEA) were measured in subsurface drainage and shallow groundwater beneath continuous, no‐till corn. Water samples were collected from the subsurface drain (tile) outlets and suction lysimeters in the growing seasons of 1990 and 1991, and analyzed for atrazine and two principle degradates using solid‐phase extraction and HPLC. In 1990, atrazine concentration ranged from 1.3 to 5.1 µg L−1 in tile‐drain water and from 0.5 to 20.5 µg L−1 in lysimeter water. In general, concentrations of parent and degradates in solution were atrazine > DEA > DIA. Lesser levels of atrazine were measured in 1991 from Plots 2 and 4; however, greater concentrations of atrazine (6.0–8.4 µg L−1) were measured from Plot 5. Throughout the two growing seasons, atrazine concentration in Plot 5 tile‐drain water was greater than that of Plots 2 and 4, suggesting a preferential movement of atrazine. Concentrations of DIA and DEA ranged from 0.1 to 2.2 and 0.9 to 3.2 µg L−1, respectively, indicating that the degradation products by themselves or in combination with parent atrazine can exceed the maximum contaminant level (mcl) of 3 µg L−1 even though atrazine by itself may be <3 µg L−1. The deethylatrazineto‐atrazine ratio (DAR) is an indicator of residence time in soil during transport of atrazine to groundwater. In Plots 2 and 4, DAR values for tile‐drain water ranged from 0.43 to 2.70 and 0.50 to 2.66, respectively. By comparison, a DAR of 0.38 to 0.60 was observed in Plot 5, suggesting less residence time in the soil.
The Role of Turfgrasses in Environmental Protection and Their Benefits to Humans
Authors: Beard James B , Green Robert L.
Published: July 2010

Turfgrasses have been utilized by humans to enhance their environment for more than 10 centuries. The complexity and comprehensiveness of these environmental benefits that improve our quality‐of‐life are just now being quantitatively documented through research. Turfgrass benefits may be divided into (i) functional, (ii) recrcational, and (iii) aesthetic components. Specific functional benefits include: excellent soil erosion control and dust stabilization thereby protecting a vital soil resource; improved recharge and quality protection of groundwater, plus flood control; enhanced entrapment and biodegradation of synthetic organic compounds; soil improvement that includes CO2 conversion; accelerated restoration of disturbed soils; substantial urban heat dissipation‐temperature moderation; reduced noise, glare, and visual pollution problems; decreased noxious pests and allergy‐related pollens; safety in vehicle operation on roadsides and engine longevity on airfields; lowered fire hazard via open, green turfed firebreaks; and improved security of sensitive installations provided by high visibility zones. The recrcational benefits include a low‐cost surface for outdoor sport and leisure activities, enhanced physical health of participants, and a unique low‐cost cushion against personal impact injuries. The aesthetic benefits include enhanced beauty and attractiveness; a complimentary relationship to the total landscape ecosystem of flowers, shrubs and trees; improved mental health with a positive therapeutic impact, social harmony and stability; improved work productivity; and an overall better quality‐of‐life, especially in densely populated urban areas.
A Microcosm for Soil‐Atmosphere Gas Transfer Investigations
Authors: Ewing Lyn L. , Sheppard Marsha I.
Published: July 2010

Proposed disposal of high‐level nuclear wastes containing primarily inorganic 14C may provide a source of 14CO2 to the atmosphere. Laboratory experiments show that the loss of inorganic 14C is driven primarily by gaseous diffusion and is affected by the pH, porosity, temperature, moisture, and organic matter content of the soil. Two soil microcosms were designed to determine the degassing rate of volatile contaminants for the top 0.3 m of soil, the depth generally defined as the root zone in environmental assessment models. The performance of the system was evaluated in an investigation of the major factors affecting the transport of 14CO2 across the soft‐atmosphere boundary. These microcosms were used in a flow‐through system that allowed for manipulation and monitoring of parameters such as airflow, air moisture levels, air‐CO2 concentration and soil temperature and soil moisture with soils of different pH and organic matter content. The performance of the microcosms was assessed for 14CO2 using soil slurries and soil columns. The evolved 14CO2 was trapped in a series of NaOH gas traps, which were frequently sampled and analyzed. Profiles of soil moisture content, soil temperature and 14C activity could be established. This laboratory system was useful in estimating the rate at which 14CO2 is released from soil. Other traps could be tested for use with other soil contaminants.
Soil Tillage Effects on Ammonia Volatilization from Surface‐Applied or Injected Animal Slurry
Authors: Sommer S. G. , Ersbøll A. K.
Published: July 2010

Ammonia (NH3) losses from cattle (Bos sp.) and pig (Sus scrofa) slurry applied to a harrowed and unworked soil were studied in seven field experiments from October 1990 to December 1991. In one experiment slurry was directly injected into the soil and hi six experiments slurry was surface‐applied. Ammonia losses were measured with a wind tunnel system. From directly injected slurry applied to a recently harrowed soil, NH3 losses were 30% of the losses from an unworked soil. Harrowing the soil immediately before surface application of the slurry reduced losses to less than 50% of the losses from an unworked soil. The accumulated NH3 loss from slurry applied in the field was described with a Michaelis‐Menten‐like equation, showing the NH3 loss reaction modeled adequately as a first‐order reaction. The effect of treatment, soil conditions, or environmental conditions on NH3 loss pattern from slurry applied in the field may therefore be treated statistically by comparing the parameters in the Michaelis‐Menten equation.
Photosynthetic and Growth Responses of Two Broad‐Leaf Tree Species to Irrigation with Municipal Landfill Leachate
Authors: Shrive S. C. , McBride R. A. , Gordon A. M.
Published: July 2010

A study was undertaken to investigate leaf photosynthesis and stem growth responses of saplings of two broad‐leaf tree species to irrigation with municipal solid waste (MSW) leachate in a northern temperate climate at Ontario, Canada. The objective was to quantify plant stresses or changes in plant productivity that could be attributed to this low technology option for the treatment and disposal of groundwater contaminated by municipal refuse. Red maple (Acer rubrum L.) and hybrid poplar [Populus spp. nigra × maximowiczii (NM6)] were subjected to two consecutive seasons of leachate irrigation in a three factor, RCBD split‐plot field experiment. The three factors were irrigant type (MSW leachate, water), mode of application (spray, surface trickle, subsurface irrigation), and rate of application (3.5, 7.0, and 14.0 mm d−1). The main treatment plots in each of three blocks were split into subplots planted to different tree species. In the second irrigation season, the mean seasonal photosynthesis rates increased for irrigated saplings of both species relative to rain‐fed control saplings, irrespective of irrigant type. Mean seasonal photosynthesis rates for red maple increased with irrigant application rate, but were unaffected by irrigant type. Incremental stem diameter and height growth for this species were largely unaffected by the experimental treatments. Mean seasonal photosynthesis rates for hybrid poplar were unaffected by either irrigant type or application rate, but stem growth did increase significantly with leachate irrigation. The mode of irrigant application was not a significant factor in explaining plant response for either species. Direct exposure of leaves to potentially phytotoxic compounds in MSW leachate (volatile organics, and inorganics including metals) by spraying did not induce phytotoxic symptoms in the saplings. Irrigation of a MSW leachate of relatively high ionic strength can be carried out successfully on clay soils under Ontario climatic conditions without causing significant adverse effects on saplings of these tree species. Treatment and disposal of MSW leachates in tree plantations may offer a low technology, low cost option to municipalities.
Transport of Chlorsulfuron through Soil Columns
Authors: Veeh R. H. , Inskeep W. P. , Roe F. L. , Ferguson A. H.
Published: July 2010

Chlorsulfuron [2‐chloro‐N‐[[(4‐methoxy‐6‐methyl‐1,3,5‐triazin‐2‐yl)amino]carbonyl]‐benzenesulfonamide] is an anionic sulfonylurea herbicide with high soil persistence; consequently, there is interest in predicting its mobility hi agricultural soils. The objectives of this study were to determine the transport characteristics of chlorsulfuron in disturbed and undisturbed soil columns and evaluate the capabilities of LEACHM (Leaching Estimation and Chemistry Model) for predicting chlorsulfuron transport. Soil column experiments were conducted with two Montana soils (Amsterdam silt loam, file‐silty, mixed Typic Haploboroll, and Haverson silty clay loam, fine‐loamy, mixed (calcareous), mesic Ustic Torrifluvent) under unsaturated flow conditions. Unit gradient was established in all columns by balancing surface water input to outflow at the bottom of each column through a stainless steel porous plate connected to a vacuum chamber containing a fraction collector. A nonlinear least squares approach (CXTFIT) was used to fit breakthrough curves (BTCs) for Br− and 14C‐labeled chlorsulfuron using the linear equilibrium adsorption model (i.e., local equilibrium assumption or LEA model) and the bicontinuum model (i.e., nonequilibrium assumption). Observed Br− BTCs were best described by the bicontinuum model indicating physical nonequilibrium due to immobile water regions. Observed chlorsulfuron BTCs demonstrated both chemical and physical nonequilibrium during transport. The best fit to observed chlorsulfuron BTCs was obtained with the bicontinuum model using the dispersion coefficient optimized (i.e., fixed) from the Br− BTCs. LEACHM was used to generate predicted BTCs for chlorsulfuron utilizing independently measured or estimated soil physical parameters as input data. Predicted BTCs utilizing the Br−‐derived dispersion coefficient (D) and the bicontinuum model‐derived partition coefficient (Koc) did not adequately reflect observed BTCs primarily because the current version of LEACHM has no capability for accepting input parameters relating to nonequilibrium conditions. The D and Koc values for chlorsulfuron BTCs derived from the LEA model improved predictions; however, it is important to note that LEA‐derived D and Koc values for chlorsulfuron BTCs essentially compensate for nonequilibrium behavior. Finally, the experimentally determined chlorsulfuron BTCs confirmed the high mobility of this chemical at neutral soil pH values.
Seasonal Variation in Methane Emission from Stored Slurry and Solid Manures
Authors: Husted Søren
Published: July 2010

Methane (CH4) is an important greenhouse gas and recent inventories have suggested that livestock manure makes a significant contribution to global CH4 emissions. The emission of CH4 from stored pig slurry, cattle slurry, pig solid manure, and cattle solid manure was followed during a 1‐yr period. Methane emission was determined by dynamic chambers. Emission rates followed a In‐normal distribution for all four manures, indicating large spatial and seasonal variations. Monthly geometric means for pig slurry, cattle slurry, pig solid manure, and cattle solid manure varied from 0.4 to 35.8, 0.0 to 34.5, 0.4 to 142.1, and 0.1 to 42.7 g CH4 m−3 d−1, respectively. For slurries CH4 emission rates increased significantly with storage temperatures, the Q10 value ranging from 3.4 to 5.7 depending on slurry type. The presence of a natural surface crust reduced CH4 emission from slurry by a factor of 11 to 12. Surface crust effects declined with increasing slurry temperature. Solid manures stored in dungheaps showed significant heat production. Pig solid manure temperatures were maintained at 30 to 60 °C throughout most of the year, while cattle solid manure temperatures were close to ambient levels until late spring, when heat production was initiated. Methanogenesis in solid manure also increased with increasing temperatures. For pig solid manure, CH4 emission rates peaked at 35 to 45 °C. No distinct temperature optimum could be detected for cattle solid manure, however, temperatures rarely exceeded 45 °C. The Q10 values for dungheaps ranged from 2.7 to 10.3 depending on manure type and Q10 temperature interval. Annual CH4 emissions from pig slurry, cattle slurry, pig solid manure, and cattle solid manure were estimated at 8.9, 15.5, 27.3, and 5.3 kg animal−1 yr−1, respectively. The annual emission of CH4 from stored animal manure in Denmark is estimated at 28 000 Mg yr−1.
Use of Mine Fills for Biological Renovation of Domestic Wastewater
Authors: Peterson C. E. , Reneau R. B. , Hagedorn C.
Published: July 2010

Development of Appalachian coal mining regions has been severely hampered by lack of domestic waste disposal technologies suited to fills. This research was conducted to evaluate the potential for biological renovation of domestic wastewater in fills produced from mining operations. Soil‐fill (a mixture of Jefferson, fine‐loamy, siliceous, mesic Typic Hapludult and Muskingom, fine‐loamy, mixed, mesic Typic Dystrochrept soils) and spoil‐fill (blasted rock material associated with the Taggart Marker and Low Splint Bench coal seams) were used in this study. Septic tank effluent (STE) and sand filter effluent (SFE) were applied to soilfill columns at four loading rates (0, 5.4, 10.8, and 21.6 L m−2 d−1) and spoil‐fill columns at one loading rate (21.6 L m−2 d−1) for a period of 20 wk. Fecal coliform numbers were reduced by 89 to 99% after passing SFE and STE through the fill columns. Coliform counts in effluent from the soil‐ and spoil‐fill columns were lower where SFE was applied as compared with STE. There were no significant differences between coliform counts in effluent from soil‐fill and spoil‐fill columns, although, there was a trend toward higher counts in effluent from the spoil‐fill columns. When soil‐fill columns were considered, coliforms were reduced more effectively (at the highest loading rate) in columns receiving SFE when compared with columns receiving STE. This study indicates that selected fills may be used when consideration is given to wastewater treatment and loading rate.
Boron Release from Fly Ash and its Uptake by Corn
Authors: Kukier U. , Sumner M. E. , Miller W. P.
Published: July 2010

The increasing costs of disposing of fly ash create an urgent need to find potential uses, one of which is land application to improve physical or chemical properties of soils. Because fly ash contains considerable amounts of B, which is often deficient in Southeastern soils, B release from fly ash and its uptake by corn (Zea mays L.) were investigated initially under greenhouse conditions. Two fly ashes from Georgia were tested as a source of B for corn grown on two soils of different texture (Cecil: clayey, kaolinitic, thermic Typic Kanhapludult, and Lakeland: thermic, coated Typic Quartzipsamment). Fresh (unweathered) fly ash was applied to Cecil soil at rates equal to 0.0, 3.1, 6.3, 12.5, 25, 50, and 100 g kg−1 soil, while the Lakeland soil being sandier received one‐half of these rates. Hot water extractable B content of fly ash increased with decreasing pH and both soils showed a linear relationship between fly ash rate and hot water extractable soil B. Soil pH was the main factor influencing B release from fly ash in soil‐fly ash systems (at given fly ash rate). Increased rates of B application in fly ash resulted in much higher tissue B contents and caused marked reductions in growth on both soils. Tissue B contents on the sandy Lakeland soil were higher at the same ash rate than on the heavier Cecil soil. Hot water extractable soil B is a good diagnostic criterion for evaluation of B availability to plants on fly ash amended soils.
Naturally Occurring Radionuclides in Agricultural Products: An Overview
Authors: Hanlon Edward A.
Published: July 2010

Low levels of naturally occurring radionuclides exist in phosphatic clays, a by‐product of phosphatic mining and beneficiation processes. Concerns about these radionuclides entering the human food chain were an immediate research priority before the phosphatic clays could be reclaimed for intensive agricultural purposes. Efforts included the assembly of a large body of data from both soils and plants, part of which were produced by the Polk County (Florida) Mined Lands Agricultural Research/Demonstration Project (MLAR/DP). Additional detailed studies involving dairy and beef cattle (Bos taurus) were conducted by researchers working with the MLAR/DP. A national symposium was conducted in which data concerning the MLAR/DP work and other research projects also dealing with naturally occurring radionuclides in agriculture could be discussed. The symposium included invited review papers dealing with the identification of radionuclide geological origins, the geochemistry and movement of radionuclides within the environment, mechanisms of plant uptake, entry points into the food chain, and evaluation of dose and risk assessment to the consumer of low levels of radionuclides. The risk to human health of an individual obtaining 0.1 of his or her dietary intake from crops produced on phosphatic clays increased by 1 in 5 × 106/yr above a control individual consuming no food grown on phosphatic clays. Leaf tissues were found to be generally higher than fruit, grain, or root tissues. The natural range in radionuclide content among various food types was greater than the difference in radionuclides content between the same food produced on phosphatic clays vs. natural soils.
Plant and Soil Relationships of Uranium and Thorium Decay Series Radionuclides—A Review
Authors: Mortvedt J. J.
Published: July 2010

The behavior of radionuclides of the uranium (U) and thorium (Th) decay series in terrestrial systems is of interest because of environmental effects of mining and disposal activities related to nuclear power plant fuels. The soft‐plant relationships of U, Th, and polonium (Po), and some other daughter radionuclides, notably radium (226Ra), are not well understood. Most studies have been concerned with relative uptake of these radionuclides by various plant species. Plant concentrations have been related to total contents of these radionuclides in the soil as a plant/soil concentration ratio (CR), even though the fraction of these radionuclides, which may be available to plants, is not well known. These CR values have been used to predict transport of radionuclides and other elements of interest through the food chain as well as for other purposes, including biogeochemical exploration for U. Little information is available on uptake and transport mechanisms of radionuclides in plants. However, the mechanisms relating to Ca uptake and translocation in plants may be similar to those of some radionuclides, especially 226Ra. Soil chemical reactions of these radionuclides also have not been studied as well as those of plant nutrients, although knowledge of the effects of soil pH, soil texture, and organic matter content on uptake, as well as mobility in soil of these radionuclides, has been gained in recent years.
Microbial Effects on Nickel and Cadmium Sorption and Transport in Volcanic Tuff
Authors: Brown Robin L. , Bowman Robert S. , Kieft Thomas L.
Published: July 2010

We performed sorption and transport experiments to determine how vadose‐zone microbes affect sorption of Ni2+ and Cd2+ on crushed volcanic tuff and transport of Ni2+ in the same medium. Sorption of Ni2+ and Cd2+ to the tuff was less in samples inoculated with microbes than in sterile samples. Since Ni2+ sorption was the same both in the presence and absence of microbes when a buffer was used, microbes appear to decrease sorption by decreasing solution pH. Samples with Bacillus megaterium decreased Ni2+ sorption the most of the 14 subsurface microbial strains tested. Nickel isotherms were linear up to initial concentrations of 10 mg L−1 with an average distribution coefficient (kd) of 7.4 L kg−1 for samples with freeze‐dried B. megaterium and 50 L kg−1 for sterile samples containing 1 g L−1 NaN3. Sterile samples without NaN3 had a higher kd (84–265 L kg−1). We therefore predicted that the retardation of Ni2+ in inoculated columns would be lower than in sterile columns. A transport experiment with both inoculated (inoculum consisted of freeze‐dried B. megaterium) and sterile (solutions contained NaN3) columns indicated that retardation (R) of Ni2+ was less for columns with microbes (R = 205) than for sterile columns (R = 307), but retardation was higher than predicted by batch sorption experiments in both groups of columns. Dispersion was lower in inoculated columns, possibly due to microbial clogging of secondary pores. The results indicate that microbes can increase the mobility of cationic metals in subsurface environments.
Groundwater Nitrate Levels under Fertilized Grass and Grass‐Legume Pastures
Authors: Owens L. B. , Edwards W. M. , Van Keuren R. W.
Published: July 2010

High levels of N fertilizer applied to pastures can result in NO3‐N concentrations in groundwater exceeding the USEPA potable water standard of 10 mg N/L. This study was conducted to determine groundwater NO3‐N levels following a change in N source from fertilizer to a legume in a grass‐pasture grazed by beef cattle. For 5 yr, 224 kg N/ha was applied annually to small watersheds with orchardgrass (Dactylis glomerata L.) pastures used for summer‐grazing and tall fescue (Festuca arundinacea Schreb.) areas used for winter‐grazing‐feeding. At the beginning of the sixth year, alfalfa (Medicago sativa L.) was interseeded into the grass pastures and N fertilizer was no longer applied. Groundwater sampies from developed springs and surface runoff samples were collected and analyzed for NH4‐N, NO3‐N, and total N for the 5‐yr fertilization period and for the following 10‐yr period without applied N fertilizer. Nitrogen in groundwater was present mainly in the NO3 form, and concentrations increased throughout the 5‐yr period of fertilizer application and reached levels that were usually in excess of 10 mg N/L. With the change from N fertilizer to legume N, the NO3‐N concentrations in groundwater dropped rapidly during a 2‐yr period. In a tall fescue‐alfalfa area, NO3‐N levels decreased from 17.7 to 9.3 mg N/L. In two orchard‐grass‐alfalfa areas, NO3‐N levels decreased from 11.2 to 2.7 and from 8.3 to 3.6 mg N/L. During the remainder of the 10‐yr period, NO3‐N concentrations declined to levels similar to those before N fertilization. Although the amount of N lost via subsurface flow decreased with decreasing concentrations, subsurface flow remained the main pathway for N loss compared with surface runoff or sediment‐attached N.