bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nitrogen Leaching as Influenced by Nitrogen Management and Supplemental Irrigation Level
Authors: Timmons D. R. , Dylla A. S. 
Published: July 2010

AbstractCorn (Zea mays L.) management systems involving two nitrogen (N) fertilization methods and two supplemental irrigation levels were evaluated for soil water percolation and N leaching losses in west central Minnesota. Nonweighing lysimeters were used to collect soil water and the accompanying nutrients that moved below the root zone of the droughty Estherville sandy loam soil studied. Nitrogen was applied either as granules broadcast and disked in before planting or in liquid form through the irrigation system four times during the growing season. Supplemental irrigation was applied as either a partial replenishment (2.5 cm) or full replenishment (5 cm) irrigation each time the available soil water decreased to about 5 cm (50% depletion).Annual soil water percolation from spring thaw to fall freezeup averaged about 7.1, 11.2, and 18.0 cm for nonirrigated corn, 2.5‐cm irrigated corn, and 5‐cm irrigated corn, respectively, during the 5‐year period studied. Average annual NO3‐N leaching losses ranged from about 29 (for nonfertilized, nonirrigated corn) to 112 kg ha−1, and the combination of variable rainfall, soil NO3‐N content, and low soil water‐holding capacity caused great variation within and among years. Compared with values for fertilized nonirrigated corn, annual NO3‐N leaching losses increased an average of 17 and 53%, respectively, for the partial and full replenishment irrigations. The periodic application of liquid N through the irrigation system reduced average annual NO3‐N leaching loss by about 12 kg ha−1 at the 5‐cm irrigation level, but no difference resulting from N management was observed at the 2.5‐cm level.
Renovation of Septic Tank Effluent in Sand‐Clay Mixtures
Authors: Willman B. P. , Petersen G. W. , Fritton D. D. 
Published: July 2010

AbstractSand required by Pennsylvania code for use in elevated sand mounds is not specified by sand mineralogy but does require 5–15% clay by weight. Since this required sandy material is expensive and research elsewhere would suggest that a specific clay percentage is not required, the objective of this research was to test the validity of the clay content requirements and the effect of sand mineralogy on septic tank effluent renovation.Limestone, sandstone, and shale sands were used with clay added to give 0, 3, 6, and 12% clay. Septic tank effluent was applied at the rate of 1.5 cm/day to the surface of each sand‐clay mixture for 23 weeks. The effluent was analyzed at regular intervals before and after flowing through 60 cm of the sand for the following 16 chemical and biological variables: pH, chemical oxygen demand (COD), fecal coliforms, fecal streptococci, total Kjeldahl N, NH4‐N, NO2‐N, NO3‐N, (NO3‐NO2)‐N, PO4‐P, total P, Cl, Ca, Na, K, and specific conductivity. All the sand‐clay combinations (including the 0% clay samples) removed over 99% of the fecal coliforms and streptococci. The removal of P and COD and the transformation of N were highly efficient in the limestone and shale sands regardless of clay content. Renovation in the sandstone sand, which is a relatively inert material, was increased by the addition of small amounts of clay. It was concluded that sand type influences the renovation of effluent and is more important than the amount of clay. The results of this study indicate that limestone is the most desirable sand type, although long‐term dissolution may be a problem, followed by sandstone with a small percentage of clay, and then by shale. Although shale was a relatively efficient renovator of effluent over the time period studied, it is anticipated that the susceptibility of shale to weathering would lead to early clogging.
Volatile Fatty Acids in a Redox‐Controlled Cattle Manure Slurry
Authors: Guenzi W. D. , Beard W. E. 
Published: July 2010

AbstractFatty acids have been implicated as a part of the overall odor problem associated with the management of animal wastes. This study was conducted to determine the relationship between redox potential (Eh) and volatile fatty acid (VFA) transformations in a cattle manure slurry. The controlled redox system was sequentially lowered in 100‐mV increments from +300 to −200 mV, and acid concentrations of the suspension were determined by gas chromatography. Acids associated with the added dry manure disappeared at + 300 mV Eh, and only acetic acid was detected at very low concentrations at Eh levels of +200, +100, and 0 mV. Acetic, propionic, and isobutyric acids started to accumulate at −100 mV and butyric acid began to accumulate at −200 mV. The rate of acid formation was considerably higher at −200 mV than at −100 mV, except for isobutyric concentrations, which began forming at −100 to −200 mV but remained consistently low. Acid accumulations during the 7‐day period at −200 mV were 6.66, 0.86, and 0.05 mg/g manure for acetic, propionic, and butyric acids, respectively. Saturated manure samples incubated at constant temperatures ranging from 5 to 35°C reached an Eh of −100 mV after 2 hours at 5°C and after 1 hour at 15°C. A −200‐mV Eh was reached after 0.5 hour at 25 and 35°C. Therefore, the conditions required for acid formation and, perhaps, release as odor components, could occur within hours after a feedlot has received moisture that initiates and accelerates microbial activity.
Effects of Sewage Sludge on Phenoxy Herbicide Adsorption and Degradation in Soils
Authors: O'Connor G. A. , Fairbanks B. C. , Doyle E. A. 
Published: July 2010

AbstractThe adsorption and degradation of two herbicides, 2,4,dichlorophenoxyacetic acid (2,4‐D) and 2,4,5‐trichlorophenoxyacetic acid (2,4,5‐T), were examined in three soils either freshly amended or preconditioned for 2 months with sewage sludge. Sludge additions generally enhanced herbicide degradation, but had no effect on 2,4‐D degradation in a soil with a history of 2,4‐D applications. Fresh sludge additions had little effect on herbicide adsorption by soils, while preconditioning the sludge‐soil mixtures generally increased herbicide adsorption.
Chemical Availability of Cadmium in Mississippi River Sediment
Authors: Khalid Rashid A. , Gambrell Robert P. , Patrick William H. 
Published: July 2010

AbstractThere is concern that changes in the physicochemical conditions occurring during dredging and disposal of polluted sediments may increase chemical mobility and hence bioavailability of sediment‐bound toxicants such as Cd. The objectives of this research were to study the chemical transformations of Cd in freshwater sediment as affected by pH and redox potential under controlled laboratory conditions and predict Cd behavior during dredging and disposal of Cd‐contaminated sediments.Mississippi River sediment suspensions were incubated at four redox potential levels (−150, +50, +250, and +500 mV) at each of three pH levels (5.0, 6.5, and 8.0) and spiked with 0.2 µCi carrier‐free 109Cd/g solids. Sediment suspensions were sequentially extracted for easily mobile and potentially available 109Cd fractions. Essentially all of 109Cd extracted from alkaline sediment suspensions was associated with potentially available chelated, insoluble organic‐bound and reducible fractions and was not affected by changes in oxidation‐reduction conditions. A change from alkaline to acidic pH under moderately oxidized to well‐oxidized conditions resulted in 109Cd transformations from potentially available organic forms to more mobile and readily available dissolved and exchangeable forms. This could create potential hazards of disposal of Cd‐contaminated dredged sediments due to enhanced availability and leaching of Cd as affected by altered physicochemical environments.
Spatial and Temporal Variation of Fecal Coliform Movement Surrounding Septic Tank‐Soil Absorption Systems in Two Atlantic Coastal Plain Soils
Authors: Stewart L. W. , Reneau R. B. 
Published: July 2010

AbstractField experiments involving residential, conventional septic tank‐soil absorption systems (ST‐SAS) were conducted to determine the extent, direction, and seasonal variation of fecal coliform movement away from drainfields placed in two poorly drained Coastal Plain soils with seasonally high fluctuating water tables. Monitoring wells at 152‐ and 305‐cm depths were placed in and around two ST‐SAS that had been in operation for about 2 years. Fecal coliform levels were measured one to two times per month from January 1977 to September 1979. One site had effective artificial drainage that created a water table gradient of 3.2% and resulted in lateral mass flow of bacteria, up to 10 m, in the direction of the gradient. At this site the predominate fecal coliform movement was horizontal, as indicated by an average concentration of <3 Most Probable Number (MPN)/100 ml in the deep wells within the drainfield. The lack of a discernible water table gradient at the second site, which employed only shallow surface drains, resulted in downward movement of fecal coliforms with the deep wells, averaging 10 MPN/100 ml compared with the 45 MPN/100 ml average in the shallow wells within the drainfield. Fecal coliform movement at both sites was almost entirely limited to periods when the water table was at or above the drainfield trench bottoms. Nonuniform distribution of septic tank effluent throughout the entire drainfield was apparent at both locations. The results indicate placement of conventional ST‐SAS in high‐water‐table soils may result in contamination of shallow ground waters (305 cm).
Accumulation of Heavy Metals in Arid‐Zone Soils Irrigated with Treated Sewage Effluents and Their Uptake by Rhodes Grass
Authors: Banin A. , Navrot J. , Noi Y. , Yoles D. 
Published: July 2010

AbstractProlonged commercial irrigation with treated sewage effluents from rural sources resulted in accumulation of heavy metals in the top 10‐ to 15‐cm layer of the soil in three commercial fields. Statistically significant differences were found for total content and extractable fraction of Cd in all three soils, and for Cu, Ni, and Pb in clay soils by comparing these fields and adjacent ones irrigated with normal water. Chromium concentration differences were not statistically significant. As a result, there was some increase in the concentration of these elements in Rhodes grass (Chloris gayana Kunth.) grown in the sewage‐effluent‐irrigated fields as compared with the grass grown in the fields irrigated with normal water. The increase, although statistically significant, was slight, even in the field that had been irrigated with sewage effluents for up to 28 years. The uptake of the various metals, as assessed by the enrichment factor (EF = µg element g−1 plant/µg element g−1 soil), tended to diminish with an increase in the specific surface area of the soil. This was particularly pronounced with the more labile of the elements studied—Cd, Cu, and Ni—and less so for Pb and Cr. The uptake of a given element appears to be largely determined by its solubility in the soil solution and can be generally predicted by its ionic potential. The relative magnitude of the enrichment factor established for Rhodes grass is in the following order: Cu > Cd > Pb > Ni ≫ Cr.
Effect of Simulated Acid Rain on Nitrification and Nitrogen Mineralization in Forest Soils
Authors: Strayer Richard F. , Lin Chyi‐Jiin , Alexander Martin 
Published: July 2010

AbstractTo determine the possible microbiological changes in soil resulting from acid rain, columns containing samples of forest soils were leached with either a continuous application of 100 cm of simulated acid rain (pH 3.2–4.1) at 5 cm/hour or an intermittent 1.5‐hour application of 1.2 cm of simulated acid rain twice weekly for 19 weeks. The upper 1.0‐ to 1.5‐cm portions of soil from treated columns were used to determine the changes in inorganic N levels in the soil. Nitrification of added ammonium (NH4+) was inhibited following continuous exposure of soil to simulated acid rain of pH 4.1−3.2. The extent of the inhibition was directly related to the acidity of the simulated rain solutions. The production of inorganic N in the absence of added NH4+ was either stimulated or unaffected following continuous treatment of soils with pH 3.2 simulated acid rain. The addition of nitrapyrin (2‐chloro‐6‐[trichloromethyl]pyridine), an inhibitor of autotrophic nitrification, caused a decrease in nitrification in water‐treated soil but had little effect on nitrification in soil treated with pH 3.2 simulated acid rain. Intermittent applications of simulated acid rain (pH 3.5–4.1) for 19 weeks partially inhibited nitrate (NO3−) production in soil amended with NH4+ following the exposure period, but NO3− production in unamended soil was either unaffected or stimulated.
Occurrence of Naturally High Cadmium Levels in Soils and Its Accumulation by Vegetation
Authors: Lund L. J. , Betty E. E. , Page A. L. , Elliott R. A. 
Published: July 2010

AbstractA survey of soils in the Santa Monica Mountains of Los Angeles and Venture Counties, Calif., was conducted to determine the relationship between parent materials and soil Cd contents. Twenty‐four series were sampled and analyzed for Cd after digestion in 4N HNO3. Residual soils developed from shale parent materials had the greatest Cd concentrations, with a mean of 7.5 µg/g, whereas soils developed from sandstone and basalt had the lowest Cd concentrations, with a mean of 0.84 µg/g. Alluvial soils with parent materials from mixed sources had an intermediate mean Cd content of 1.5 µg/g. A more extensive survey of the dominant soil series of the area was carried out and the Millsholm series, mapped in 30% of the area, was found to have a mean Cd content of 7.3 µg/g. A greenhouse vegetable study conducted with seven soils from the area, representing a range of Cd concentrations, showed that the Cd present naturally in these soils was absorbed by the vegetables in amounts sufficient to be of public health concern.
Potential Polychlorinated Biphenyl Residues in Animal Products from Application of Contaminated Sewage Sludge to Land
Authors: Fries George F. 
Published: July 2010

AbstractLaboratory studies and field observations involving polychlorinated biphenyls (PCB's) and related compounds were used in making an assessment of residues in animal products from the application of sewage sludge to agricultural land. Animals can become exposed to PCB's applied to land by three routes: direct ingestion of sewage sludge that adheres to plants during sludge application, ingestion of plants indirectly contaminated by uptake or volatilization from the soil, and ingestion of contaminated soil when grazing. The last route has the greatest realistic potential for producing residues in animal products from a given rate of long‐term application of PCB‐contaminated sludge to land. Feeding experiments with PCB's indicate that the steady‐state milk‐fat concentrations are about five times the diet concentrations (dry basis) in dairy cattle and that the steady‐state body‐fat concentration will be similar in non‐lactating animals. Soil consumption by grazing dairy cows can be as high as 14% of dry‐matter intake when the amount of available forage is low and no supplemental feed is used. This could cause milk‐fat residues of 0.7 ppm for each ppm of PCB in surface soil. There is little root absorption and translocation of PCB's to the aerial parts of plants. Plants can become contaminated by volatilization of PCB's from soil and redeposition on the plants if the residue occurs at the soil surface. Field experience with other halogenated hydrocarbons suggest that volatilization and redeposilion of PCB's will be less important in determining rates of PCB‐containing sludge that can be applied to land than direct animal ingestion of sludge or contaminated soil.
The Occurrence of Flow Channels in Soils
Authors: Simpson T. W. , Cunningham R. L. 
Published: July 2010

AbstractSpecialized flow features (channels) described in Typic Hapludalf, clayey, mixed, mesic soils that have been used for waste‐water irrigation are reported, to explain the mechanism for widely different water‐flow velocities through soil.A field investigation of 15 soil‐pit transects revealed vertical zones of loose, porous, fine‐structured soil through which rapid saturated flow occurred. The texture of the soil in the channels was clay, as was the matrix between channels.Rapid flow of effluent‐irrigation waters through channels in the soil may lessen the renovating capability of the soil because of the reduced surface area and reduced contact time. Because the channels were coincident in some cases with carbonate bedrock solution channels, possible ground‐water pollution may have occurred.
Treatment of Secondary Sewage Effluent with a Peat‐Sand Filter Bed
Authors: Nichols Dale S. , Boelter Don H. 
Published: July 2010

AbstractA peat‐sand filter bed was constructed to provide additional treatment of the secondary sewage effluent from a campground located on the shore of North Star Lake, within the Chippewa National Forest in north‐central Minnesota. This effluent contained an average of 30.9 mg/liter total nitrogen, 8.63 mg/liter total phosphorus, and 122,000 fecal coliforms/100 ml. An average of 6.8 cm/week was applied from late May through early October for 8 years. The peat‐sand filter bed accomplished almost complete removal of fecal coliform bacteria and P. About 90% of the waste‐water N was removed during the 2nd and 3rd years of operation, but this declined to about 50% by the 5th year, due to oxidation of the peat and release of N. The high Fe, Al, and ash content of the peat contributed to the filter's highly efficient removal of P. Microbial immobilization in the peat contributed to N and P removal during the first 2 or 3 years of waste water application. Rough‐stalked bluegrass (Poa trivialis L.) planted on the peat surface of the filter was very important in overall N and P removal. Nutrient uptake by the bluegrass increased each year and accounted for 45% of the P and virtually all of the N removed from the waste water in the 5th year of the study.
Relationship Between Land‐Use Practices and Fecal Bacteria in Soils
Authors: Faust Maria A. 
Published: July 2010

AbstractFecal and other bacteria populations in soils from pasture, cornfield, and forest sites were assessed at the Rhode River watershed. Total coliform (TC), fecal coliform (FC), total streptococci (TS), fecal streptococci (FS), and aerobic heterotrophic bacteria (TVC) numbers were determined seasonally. They were also determined with depth to 25 cm in soils from the pasture. Bacterial numbers per gram of pasture soil from the surface 1 cm were: 252‐1,603 TC, 10‐3% FC, 317‐2,270 TS, 163‐1,330 FS, and 1.6‐65.1 × 106 TVC. The numbers declined markedly with depth, except that TS and TVC numbers remained near the surface values. Fecal coliform numbers varied seasonally, from 22 to 396 MPN/g soil in fall and spring when cattle were grazing, and from 10 to 50 MPN/g soil in winter and summer when cattle were absent from the pasture. The cornfield and forest surface soils contained equally low FC numbers ranging from 3 to 27 MPN/g soil. Aerobic heterotrophic bacteria were similar in magnitude at all three land‐use sites. No readily discernable seasonal pattern was noted. The proportion of coliform bacteria differed with land use. In pasture soils 67% of isolates were confirmed as Escherichia coli, 22% were Enterobacter aerogenes, and 11% belonged to other species. In cornfield soils only 8% were E. Coli, 77% E. aerogenes, and 15% other species. In forest soils only E. coli were the dominant species. Thus, the pro‐ portion of E. coli was directly related to the degree of fecal pollution of the soils, and the proportion of E. aerogenes increased with remoteness of the soil from potential polluting agents.
Prediction of Water‐Extractable Phosphorus Content of Soil Following a Phosphorus Addition
Authors: Sharpley A. N. 
Published: July 2010

AbstractThe effect of time on the water‐extractable P content (PX) of surface soil (0–10 cm) following a P addition (PA) was investigated in the laboratory using 20 soils from 14 states. The soils were incubated with P equivalent to 0‐, 25‐, 50‐, and 100‐kg/ha additions and the water‐extractable P content and soluble P concentrations of runoff from the soils determined at frequent intervals. Water‐extractable P decreased in the first 2 weeks after P addition; following this PX remained fairly constant. Water‐extractable soil P content was linearly related to PA at any given time after the addition. The slope of this relationship decreased logarithmically with time after a P addition. In the first 2 weeks after P addition, the slope of the relationship between PX and PA could be predicted from percent clay content or P sorption capacity of the soil. Using these simple relationships, an improved prediction of the amount of soluble P available for transport in surface runoff from fallow soil can be made from limited extractable soil P data.
Environmental Effects of a Medium‐Fertility 12‐Month Pasture Program: II. Nitrogen
Authors: Owens L. B. , van Keuren R. W. , Edwards W. M. 
Published: July 2010

AbstractFour small, medium fertility (56 kg/ha per year N) watersheds were used in a rotational summer‐grazing and winter‐feeding program to determine its effects on N levels in water. During a 5‐year study on sloping uplands in Ohio, the concentrations of NO3‐N and NH4‐N were determined in precipitation, surface runoff, subsurface flow, and sediment. Although the NO3‐N concentration was generally higher in the surface runoff from the summer‐grazing/winter‐feeding area than from the summer‐grazing‐only areas, it usually resulted in no significant impairment of water quality, except on a few occasions when the NO3‐N concentration exceeded 10 mg/liter. The N transported in the subsurface flow from the summer‐grazing only areas was approximately equal to that transported from the winter‐feeding area and to the amount of N received in the precipitation. Both surface runoff transport and sediment transport of N were much greater in the winter‐feeding area than in the summer‐grazing‐only areas because these latter areas yielded very little surface runoff and only a trace of soil loss. Reduction of vegetative cover and increased soil disturbance on the winter‐feeding area resulted in increased surface runoff and soil erosion and thus more N was transported. Surface and subsurface losses of N from the winter‐feeding area were nearly equal. A large percentage of N was transported by the large storms, which represented a small percentage of the total number of storms.
Prediction of Phosphorus Losses in Runoff from Southern Plains Watersheds
Authors: Sharpley A. N. , Smith S. J. , Menzel R. G. 
Published: July 2010

AbstractThe concentrations of soluble and particulate (sediment) P in runoff from several cropland and grassland watersheds across the Southern Plains were predicted from relationships obtained from simulated rainfall‐runoff studies. Soluble P was predicted from the water‐extractable P content of surface soil (0–1 cm) collected in March each year, using a general P‐extraction coefficient covering all the soils found at the watersheds studied. For individual soils the P‐extraction coefficient was related to the depth of interaction between surface soil and runoff. Particulate P concentration was predicted from the total P content of surface soil collected in March each year, using P‐enrichment ratios calculated from sediment discharge. Predictions of mean annual soluble and particulate P concentrations were good over a wide range in concentrations (50–500 and 200–5,100 µg P/liter, respectively), fertilizer and watershed management practices, soil types, and vegetative covers. The results obtained indicate that relationships used in the CREAMS model can provide accurate predictions of mean annual P concentrations.