bluuebunny/crossref_metadata_2025_split huggingface dataset:
Integrating Chemical Factors with Water and Sediment Transport from a Watershed
Authors: Frere M. H. 
Published: July 2010

AbstractA mathematical model that calculates the movement of a chemical as it is transported through or off of an agricultural watershed is described. Loss of the chemical between storms by degradation or volatilization is described by a first‐order rate equation. Simple chromatographic theory is used to describe the chemical distribution in the soil during leaching, assuming a linear adsorption relation and dispersion that is proportional to the square root of the distance moved. The concentration at the surface during the storm is calculated to estimate the amounts lost in runoff water and with interril erosion. It is assumed that rill erosion removes the chemical in proportion to the fraction of the area in rills and to the fraction of the chemical distribution in the soil intercepted by the rills.Mineralization and uptake are an additional source and sink for nitrate between storms. Lithium bromide movement on a microplot was used to examine some features of the model.
The Watershed Approach to Understanding our Environment
Authors: Woolhiser David A. 
Published: July 2010

AbstractCurrent approaches used in modeling a particular part of the human environment—the agricultural watershed—are reviewed and questions are raised regarding the objectives, approaches, and interpretation of agricultural water quality models. Models—either symbolic (mathematical) or material—are essential to understanding and predicting environmental phenomena on agricultural watersheds. Models describing the transport of water, sediment, and chemicals through a watershed system can become very complicated and frequently must be simplified. Simplifications inevitably involve distortion and may make interpretation of model parameters difficult. The use of material models may assist in interpreting the parameters of mathematical models.
Phosphate Determinations in Waters Using an Anion Exchange Resin
Authors: Blanchar R. W. , Riego Domingo 
Published: July 2010

AbstractAmounts of water samples from 1 to 1000 ml were passed through 10‐cc columns of 100‐ to 200‐mesh Dowex 1‐X8 anion‐exchange resin. Orthophosphate was quantitatively removed from the water sample by the resin and could be eluted from the column with 25 ml of 1M KCl. Phosphate in the 1M KCl eluent was reacted with ammonium molybdate, extracted into isobutanol, reduced with SnCl2, and the optical density of the blue complex measured. The working range of the method was between 1 and 8 µg of P.Arsenic does not interfere in the phosphorus determination if the phosphomolybdate complex is extracted into isobutanol before reduction with SnCl2. Pyrophosphate if present will be approximately 20% hydrolyzed and the hydrolyzed portion indicated as orthophosphate in the method described. An alternate elution procedure to separate and determine ortho‐, pyro‐, and tripoly‐phosphate eliminated condensed phosphate interference in the orthophosphate determination. Glucose‐1‐phosphate, glucose‐6‐phosphate, and glycero‐phosphate are removed from the column with the ortho‐phosphate fraction but are not hydrolyzed and indicated as ortho‐phosphate. Phytic acid phosphate and para nitrophenyl phosphate are not leached from the column with KCl and do not interfere.Analysis of water samples indicated that in the 1 to 20 ppb P range an appreciable amount of the phosphate exists as pyro‐ and tripoly‐phosphate. The resin method is not specific for dissolved orthophosphate in water, but may give a more valid estimate than direct reaction with the acid molybdate reagent.
Ethylene in Grassland Soil Treated with Animal Excreta
Authors: Burford J. R. 
Published: July 2010

AbstractEthylene was evolved in the surface layers of grassland following the application of 550 metric tons/ha of an unamended mixture of cow dung and urine (slurry) to the soil surface in the early spring (March). Concentrations in the gaseous phase of the slurry layer exceeded 2 ppm (vol/vol) during the first 3 weeks after the application, but thereafter were <0.25 ppm. In the underlying surface soil, ethylene was detected continuously for 4 months after the application: the concentration declined from about 1 ppm in April to about 0.2 ppm in July. After midsummer, significant evolution was detected only for a short period in the following winter.Measurement of ethylene concentrations in columns of soil, incubated after an application of excreta to the soil surface, showed that fresh slurry promoted ethylene accumulation in the gaseous phase more than stored slurry, and that both dung and urine stimulated ethylene evolution.
Salt Tolerance and Suitability of Various Grasses for Saline Roadsides
Authors: Hughes T. D. , Butler J. D. , Sanks G. D. 
Published: July 2010

AbstractForage yields of five grass species: Agropyron cristatum (L.) Gaertn., A. smithii Rydb., Lolium perenne L., Poa pratensis L., and Puccinellia distans (L.) Parl., were studied in soil under greenhouse conditions with NaCl additions of 0; 5,000; 10,000; and 20,000 ppm. Forage yield of P. distans was reduced 23% by addition of 20,000 ppm NaCl, compared to a minimum reduction of 40% for the other grass species. Addition of 30,000 ppm NaCl to soil completely inhibited seedling survival of A. cristatum, A. smithii, Elymus triticoides Buckl., P. distans, Puccinellia lemmoni (Vasey) Scribn., and Sporobolus airoides (Torr.) Torr. Puccinellia airoides (Nutt.) Wats. and Coult. and P. distans were unusually toleran to foliar applications of NaCl in the field.Mineral analysis of leaf tissue by emission spectroscopy showed that Na concentrations increased as NaCl addition to the soil increased. However, there was no relationship between salt tolerance of the various grasses and amounts of Na in leaf tissue. Increased NaCl addition to the soil resulted in decreased leaf Ca and Mg, but no relationship existed between leaf K and NaCl addition.P. distans is of value for vegetating saline roadsides.
Calculated Drainage Water Compositions and Salt Burdens Resulting from Irrigation with River Waters in the Western United States
Authors: Oster J. D. , Rhoades J. D. 
Published: July 2010

AbstractDrainage water compositions were calculated with a computer simulation model from irrigation water compositions, leaching fractions, aragonite and gypsum solubilities, and measured partial pressure of CO2. The calculated compositions were compared with measured values obtained from lysimeters filled with Pachappa soil, cropped with alfalfa, and irrigated with eight synthetic waters typical of rivers in the western U. S. Linear regression analysis of predicted vs. measured values for Na+ and SO42‐ concentrations, sodium‐adsorption‐ratio, electrical conductivity, and salt burden resulted in essentially one‐to‐one relationships. The gain in salt burden of drainage water at high leaching fractions due to mineral dissolution was adequately described by assuming the soil solution was saturated with respect to aragonite. Some evidence for Mg2+ precipitation was found.The utility of the simulation model is demonstrated for evaluating the salinity, sodicity, and pollution hazards of irrigation waters. The evaluation of irrigation water quality in terms of minimum leaching fractions commensurate with maintaining satisfactory salinity, and sodicity levels is illustrated using recent crop tolerance data for alfalfa and the hydraulic conductivity characteristics of several representative soils. For salt‐tolerant plants leaching fractions between 0.05 to 0.1 should be safe for six of the eight waters. Salt burdens of drainage waters are predicted to decrease with decreasing leaching fraction and partial pressure of CO2. The predicted relative decrease in salt burden ranged from 0.32 to 0.85 for a decrease in leaching fraction from 0.33 to 0.04.
Nitrate Reduction and Associated Microbial Populations in a Ponded Hanford Sandy Loam
Authors: Volz M. G. , Belser L. W. , Ardakani M. S. , McLaren A. D. 
Published: July 2010

AbstractA field plot of Hanford sandy loam was ponded for 2 weeks with a solution of KNO3 and Ca(NO3)2 containing 100 ppm NO3‐N in order to measure short term denitrification rates as well as growth and distribution of bacteria capable of reducing nitrate to nitrite and/or N2O and N2.Denitrifying bacteria (101−2.9 × 104/g soil) generally decreased in number with depth and time and were not as numerous as nitrate reducers (101−6.9 × 105/g soil).In the top 60 cm of soil, the concentration of NO2−‐N in soil solution corresponded to minima in NO3−‐N, suggesting that NO3− reduction gave rise to the NO2−. Denitrification rates calculated for the top 16 cm of water‐saturated soil were estimated to range from 0.013 to 0.046 µg N/hour g−1. The highest value was about 80% of that measured in a laboratory soil column studied previously. This difference in denitrification rates may be due to lower soil carbon content in the field.
Occurrence of 2,4,5‐T and Picloram in Subsurface Water in the Blacklands of Texas
Authors: Bovey R. W. , Burnett Earl , Richardson Clarence , Baur J. R. , Merkle M. G. , Kissel D. E. 
Published: July 2010

AbstractThis investigation was conducted to determine the concentration of 2,4,5‐T [(2,4,5‐trichlorophenoxy)acetic acid] and picloram (4‐amino‐3,5,6‐trichloropicolinic acid) in subsurface water after spray applications of the herbicides to the surface of a seepy area watershed and lysimeter in the Blacklands of Texas.A 1:1 mixture of the triethylamine salts of 2,4,5‐T + picloram was sprayed at 2.24 kg/ha every 6 months on the same area for a total of five applications. Herbicide content in the Houston Black clay during the study ranged from 0 to 162 ppb. Herbicide content on grass was high (28 to 113 ppm) immediately after spraying, but degraded rapidly after each treatment. Concentration of 2,4,5‐T and picloram in seepage and well water from the treated area was extremely low (<1 ppb) during the 3‐year study. No 2,4,5‐T was detected from 122 drainage samples from a field lysimeter sampled for 1 year after treatment with 1.12 kg/ha of 2,4,5‐T + picloram (1:1). Picloram was detected in small amounts (1 to 4 ppb) 2 to 9 months after treatment in lysimeter water.
The Nitrogen Balance of Arctic Tundra: Pathways, Rates, and Environmental Implications
Authors: Barsdate Robert J. , Alexander Vera 
Published: July 2010

AbstractThe magnitude of the inputs and exports of nitrogen was estimated for the tundra ecosystem at Barrow, Alaska. Based on new data and on previous investigations, annual input of nitrogen from all sources was 92.4 mg N/m2 per year, with the most important sources being nitrogen fixation (75%) and ammonia in summer rain (18%). The low input of nitrogen by rain and snow results from both low annual precipitation and extremely low concentrations of nitrogen compounds in precipitation. Despite the meager nitrogen supply, the estimated retention is over 80% of the input, reflecting insignificant leaching due to the impermeable permafrost substrate, low precipitation, and restricted lateral movement of water over and through the nonfrozen soils. Denitrification also is low, at least partially due to nutrient deficiency.Interpretations of these data in respect to the sensitivity of the environment to perturbations, suggest that resource development or other activities which would have minor or negligible effects in temperate latitudes, could alter substantially the nitrogen balance of this arctic ecosystem.
Rate of Chloride and Water Movement in Southern California Soils
Authors: Tullock R. J. , Coleman N. T. , Pratt P. F. 
Published: July 2010

AbstractColumn experiments in the laboratory showed an increase of 2 to 25% in the relative rate of chloride movement in soils to water when the movement of water was calculated on a total pore‐volume basis. The increase was explained as a result of anion exclusion next to the surfaces of negatively charged soil colloids. The relative rate of flow was decreased when the moisture retained by the air dry soils was deleted from the total pore solution. For soils containing sufficient clay to result in a cation exchange capacity greater than 10 meq/100 g, an equation was developed relating the fraction of the pore solution in equilibrium with anions to the cation exchange capacity. Calculated transit times for anion movement from the soil surface to ground waters should include a correction for the volume of exclusion.
Natural and Agricultural Ecosystems
Authors: Smith D. F. , Hill D. M. 
Published: July 2010

AbstractIt is argued that the task of creating awareness of environmental problems will require more than the bringing together of papers from a range of disciplines. It will depend on new consciousness and channels of communication. As an example of problems with terms, this paper analyses the use of natural and agricultural ecosystems, suggesting that on all valid criteria these form a continuum, rather than two discrete systems.
Oxygen Relationships in a Soil Treated with Sewage Effluent
Authors: Klausner Stuart D. , Kardos Louis T. 
Published: July 2010

AbstractField plots which have been irrigated with chlorinated secondary treated sewage effluent were examined for their aeration conditions using diffusion chambers and platinum microelectrodes. Average gaseous oxygen concentrations to a depth of 46 cm ranged from 19.6 to 19.0 to 18.4% as weekly application of effluent changed from 0 cm to 2.5 cm to 5.1 cm. Oxygen diffusion rates (ODR) measured by the polarographic method were not significantly different for the three effluent levels and ranged from 22.9 to 19.5 × 10−8 g O2 cm−2 min−1 from the control plot to the 5.1 cm per week plot. Oxygen diffusion rate values diminished with depth with a minimum of 15 at 46 cm and a maximum of 27 at 8 cm. Gaseous oxygen concentration was not affected by crop cover (corn or hay) but ODR was less under hay than under corn. Water samples obtained at depths of 15.2 and 61 cm with suction lysimeters showed significantly greater NO3−‐N levels in the 5.1 cm effluent treatment plots, in the corn plot and at the 61 cm depth. Nitrite‐N levels were also greater in the 5.1 cm effluent treatment but less in the corn plot than with hay. In all cases, nitrite levels were very low. Ammonium‐N levels were also greater in the 5.1 cm effluent treatment but there were no differences with respect to vegetative cover or soil depth. Manganese and iron levels in the soil water were not affected by effluent treatment. Application of 5.1 cm of sewage effluent at weekly intervals has not degraded the aeration status of the soil.
Nitrate Reduction and Nitrite Utilization by Nitrifiers in an Unsaturated Hanford Sandy Loam
Authors: Volz M. G. , Belser L. W. , Ardakani M. S. , McLaren A. D. 
Published: July 2010

AbstractIn order to discern any relationship between added nitrate and microbial growth in a field plot, a Hanford sandy loam was infiltrated for 5 weeks at a rate of 5 cm day−1 with a solution containing 100 ppm ‐N and 1.25 meq/liter Cl− as KNO3 and CaCl2 respectively. Nitrate‐N, NO2−‐N and Cl− concentrations in soil solution were determined and corresponding counts of nitrate reducers, denitrifiers, and NH4+‐ and NO2−‐oxidizer populations were made.Ratios of measured to applied concentrations for both NO3−‐N and Cl− were nearly identical in all solution samples taken from the unsaturated soil profile, i.e., nitrate reduction was not pronounced and NO2−‐N was less than 1 ppm.Nitrate reducer populations (6x104–6x105/g soil) were always larger than those of denitrifiers (3x103–3x104/g) and varied little with time and depth. Ammonium oxidizers (101–105/g) generally decreased with depth. In contrast, NO2− oxidizers (101–3x106/g) varied markedly with time at all depths. An increase in numbers of NO2− oxidizers, after 2 to 3 weeks, at a depth of 60 cm, is attributed to NO2− produced by reduction of NO3− at anoxic microsites within the profile. Evidently, a cyclic oxidation and reduction of nitrite and nitrate, occurring simultaneously, is responsible for growth of nitrite oxidizers in the profile.
Yield and Growth of Corn as Affected by Poultry Manure
Authors: Shortall J. Glenn , Liebhardt William C. 
Published: July 2010

AbstractThe effect of poultry manure on yield and growth of corn was studied on an Elkton sandy loam, typic ochraquults clayey mixed mesic, in southern Delaware. Plots with six levels of manure 0, 22, 56, 90, 168, and 224 metric tons/ha and a fertilizer treatment 224‐5‐186 kg/ha (N‐P‐K) and 22 metric tons/ha manure plus 224‐5‐186 kg/ha (N‐P‐K) were laid out in a randomized block design with four replications in 1971.Germination and yield of corn (Zea mays L.) were reduced by higher rates of poultry manure. Leaf mineral nutrition, the nitrogen fraction, organic acids, total ethanol soluble sugars, leaf water potential, leaf area index, soil salinity, and soil test data were determined to find the factors that contributed most to the yield reduction. Excessive soil salinity was considered to be the most important cause of the yield reduction following the application of high rates of poultry manure.
Movement of Fluometuron Across and Through the Soil
Authors: Baldwin F. L. , Santelmann P. W. , Davidson J. M. 
Published: July 2010

AbstractExperiments were conducted to determine the effect of rainfall intensity, antecedent soil moisture, and time and subsequent rainfall on the runoff and leaching of soil‐applied fluometuron [1,1‐dimethyl‐3‐(a,a,a‐trifluoro‐m‐tolyl)urea]. Fluometuron was applied to specially constructed field plots on a 1% slope and a simulated rainfall procedure was used to produce runoff. Runoff water and sediment, as well as vertical soil samples, were collected and analyzed for herbicide concentrations. The highest fluometuron concentrations were found on the sediment portion of the runoff, but the highest losses occurred in the liquid portion of the runoff. These losses were caused by the larger volume of water compared to sediment leaving the plot. The first 3.78 liters of runoff water leaving the plot contained a higher concentration of fluometuron than did a composite of the next 41.6 liters. Antecedent soil moisture had a greater effect on runoff losses than did rainfall intensity. Higher losses occurred when the herbicide was applied to a wet soil than to a dry soil. Fluometuron could not be detected in the runoff water collected 1 month after the first runoff‐producing water application. Total herbicide losses from each experiment were 1% or less of the total amount applied. Fluomeutron was leached to the 5‐ to 10‐cm soil depth with some treatments showing small quantities of herbicide in the 10‐ to 20‐cm layer.
Land Disposal of Broiler Litter—Changes in Soil Potassium, Calcium, and Magnesium
Authors: Jackson W. A. , Leonard R. A. , Wilkinson S. R. 
Published: July 2010

AbstractSmall plots of Cecil soil established in Kentucky‐31 tall fescue were surface applied semi‐annually with 0, 22.4, 44.8, 89.6, and 134.4 metric tons/ha of broiler litter for 2 years. Potassium and magnesium were more completely leached from the litter, 99% and 88% respectively, than calcium. At the end of two years at the highest rate, 80% of the calcium remained in the litter. After each year, chemical analysis of depth‐incremented soil samples, showed the extent of movement and redistribution of water soluble and exchangeable potassium, calcium, and magnesium. The results indicate that land disposal of broiler litter greatly enhances exchangeable K while reducing the exchangeable Ca and Mg.
Growth and Cadmium Accumulation of Plants Grown on a Soil Treated with a Cadmium‐Enriched Sewage Sludge
Authors: Bingham F. T. , Page A. L. , Mahler R. J. , Ganje T. J. 
Published: July 2010

AbstractCorn, wheat, rice, field bean, soybean, cabbage, spinach, lettuce, curlycress, carrot, turnip, radish, tomato, and squash plants were grown to commercial harvest stage using as the substrate, soil pre‐treated with a municipal sewage sludge (1%) containing variable amounts of CdSO4 up to 640 µg Cd/g soil. Observations included injury symptoms, yield decrement, Cd level of diagnostic tissue, and Cd and Zn content of harvested produce. Cadmium‐sensitive plants such as spinach, soybean, curlycress, and lettuce were injured by soil Cd levels of 4–13 µg Cd/g soil; whereas, tomato and cabbage tolerated soil levels of approximately 170 µg Cd/g soil without exhibiting injury symptoms. Rice was tolerant at all levels tested. Leafy plants such as lettuce, spinach, and turnip greens (tops) accumulated 175 to 354 µg Cd/g; whereas, fruit and seed tissue of plants under comparable treatment, with the exception of soybean, accumulated no more than 10 to 15 µg Cd/g tissue. The concentrations for soybean extended up to 30 µg Cd/g tissue. Paddy rice exhibited no ill effects for soil Cd treatments up to 640 µg Cd/g soil. Grain of plants under the 640 µg Cd/g treatment contained 2 µg Cd/g tissue. DPTA‐extractable Cd correlated (r=0.99) with the level of CdSO4 added to the substrate.
A Six‐Year Water, Phosphorus, and Nitrogen Budget for Shagawa Lake, Minnesota
Authors: Malueg Kenneth W. , Larsen D. Phillips , Schults Donald W. , Mercier Howard T. 
Published: July 2010

AbstractWater, phosphorus, and nitrogen budgets of eutrophic Shagawa Lake, Minnesota were determined from 1967–1972 to assist in defining the significance of the loading from the city of Ely secondary waste water treatment plant to the trophic state of the lake. Ely's municipal waste water accounted for about 80% of the P, 24% of the N, and only 2% of the water to Shagawa Lake while the major tributary, Burntside River, accounted for 66% of the water, 42% of the N, and only 11% of the P to the lake. An average of 30% of the P was retained within the lake.The water and nutrient budgets, along with field and laboratory studies, indicated that high levels of P from the municipal waste water treatment plant were mainly responsible for the eutrophic condition of Shagawa Lake. These studies led to the construction of a tertiary waste water treatment plant designed to remove 99+% (⩽ 0.05 mg/liter) of the P from the secondary waste water effluent. Tertiary waste water treatment should increase the N:P ratio supplied to the lake from 10.5 to 50, and would tend to produce a body of water in which P is the limiting factor in primary production. The P specific loading value of 0.73 g P m−2 year−1 will be reduced to 0.15 g P m−2 year−1.
Effect of Incubation and Contact with Soil on Microbial and Nitrogen Changes in Poultry Manure
Authors: Giddens Joel , Rao A. M. 
Published: July 2010

AbstractMicrobial and chemical changes in poultry manure as affected by incubation and contact with soil were studied, as these changes may influence potential pollution hazards. Manure and litter mixed with soil contained greater numbers of bacteria and fungi than manure alone. Fungi decreased rapidly between 7 and 14 days incubation, increasing thereafter. Fungal population was inversely related to soil pH which was directly related to NH3. Total coliform bacteria decreased more rapidly when manure was mixed with soil than when not mixed. Few coliforms survived after 28 days. Higher total coliform survival occurred in the litter than in pure manure indicating a protective effect of wood shavings. Ammonia decreased survival of coliforms. Incorporation of manure into the soil greatly increased the amount of N oxidized to NO3. Split applications of manure reduced soil NO3. Air drying of manure resulted in greater N loss than rapid drying with heat.