bluuebunny/crossref_metadata_2025 huggingface dataset:
Nitrogen Content of Shallow Ground Water in the North Carolina Coastal Plain
Authors: Gilliam J. W. , Daniels R. B. , Lutz J. F.
Published: July 2010

The NO3‐N and NH4‐N concentrations in shallow (< 3 m) ground water under a range of soil types, drainage conditions, and type of crop grown were monitored. The NO3‐N levels were always low (1 ppm or less) in ground water under wooded areas. The concentrations were somewhat higher under cultivated fields with the levels usually being 1 to 5 ppm although several values in the range of 10 to 20 ppm were recorded. The concentrations in all wells were always higher during the winter months. There seemed to be no relationship between cultivated crop and NO3‐N in the ground water. The NO3‐N concentration was almost always higher in the middle of the field than on the edge of the field even though the direction of water flow was toward the edge of the field. It is suggested that denitrification is responsible for this decrease.

There was little difference in NH4‐N concentration in water under cultivated fields and under unfertilized woods or pasture. The NH4‐N concentrations were normally in the range of 0.1 to 1 ppm with the higher levels being found under poorly‐drained soils.

Based upon the characteristics of the surface sediments, it is concluded that very little of the NO3‐N present in the shallow ground water moves into deep aquifers in any area of the North Carolina Coastal Plain. However, the amount of NO3‐N that moves through the surficial sediments to the streams probably varies with location and characteristics of the confining beds.
Erosional Losses of s‐Triazine Herbicides
Authors: Hall J. K.
Published: July 2010

Erosional losses of two chloro‐s‐triazines, atrazine and GS13529, were evaluated in 1970 and 1971 from field runoff plots planted to corn (Zea mays L.) and situated on an Hagerstown silty clay loam of 14% slope. Losses of a methoxy‐s‐triazine, GS14254, were assayed in 1971 and 1972 from an alfalfa (Medicago sativa L.) stand. Herbicides were applied preemergent to corn and to dormant alfalfa only once during the initial growing season or initial season of evaluation at two rates, 2.2 and 4.5 kg/ha. Total losses of atrazine during the first and most critical season at the respective rates were 5.0 and 4.8% of that applied and 87 to 93% of this loss resulted within the first month following application. Total losses of the related chloro‐s‐triazine were comparable at each of the rates. Both of these compounds dissipated at a moderate rate over the growing season with GS13529 showing a higher level of recalcitrance, particularly early in the season. Soil core analysis revealed that one month after application an average of 35.3% of the applied atrazine was recovered; five months later an average level of 11.8% was residual. Recovery of GS13529 ranged from 62.5 to 9.8% for the same time period.

Runoff losses of GS14254 from alfalfa were inconsequential. Little runoff was obtained from this cropping system, no sediment was ever collected and runoff concentrations of the herbicide were extremely small. Total losses of this herbicide for the year were 0.02 and 0.03% for the respective application rates.

Actual losses of water and soil to runoff in 1970 appeared to be of a more critical nature than chemical losses. Runoff losses during one particular erosion event ranged from 17% of the incident rainfall for the check plot to 68% at the low rate of atrazine. Moreover, 9800 kg/ha (4.4 tons/a) of soil were lost at the low rate. These kinds of results speak strongly for sound soil and crop management practices and conservation measures on sloping cropland.
Field Study of Solute Movement in a Highly Aggregated Oxisol with Intermittent Flooding: II. Picloram
Authors: Rao P. S. C. , Green R. E. , Balasubramanian V. , Kanehiro Y.
Published: July 2010

Most of the applied herbicide picloram (potassium salt of 4‐amino‐3,5,6‐trichloropicolinic acid) was retained in the top 40‐cm depth of the Molokai soil with cumulative applications of 48 to 74 cm water following application of the chemical to the soil surface. Distribution of picloram in the soil profile one week after each irrigation was determined by in situ sampling of soil solution with porous ceramic cups placed at several depths. Although movement of the picloram peak was retarded more than was anticipated from equilibrium adsorption measurements, a significant fraction of the applied herbicide moved ahead of the peak deep into the profile (down to the 143‐cm depth) after a single application of 24‐cm water. Rapid flow through macropore sequences combined with temporary retention of picloram in aggregate micropores appear to be responsible for the unusual pattern of movement. Published data for nitrate movement in the same field plots of Molokai soil were compared with picloram movement data to provide a measure of the relative mobility of these solutes. A comparison of the results reported here with published field data of solute leaching in other soils indicated a greater retardation of solute peak movement in Molokai soil than in less aggregated soils.
Respirometric Evidence of the Utilization of Di‐octyl and Di‐2‐ethylhexyl Phthalate Plasticizers
Authors: Mathur S. P.
Published: July 2010

Phthalic acid esters (PAEs), due to their teratogenic and mutagenic properties, threaten to disturb the ecological balance. Di‐octyl phthalate (DOP) and di‐2‐ethylhexyl phthalate (DEHP) esters are present in the environment as micropollutants, originating from industrial usages in plastics.

Because of the probability that PAEs also occur naturally, it was expected that soil and water microorganisms would utilize PAEs during the performance of their normal role in the cyclization of carbon in nature.

Since this assumption is not sufficiently supported in the literature, a study was conducted to determine whether soil microorganisms utilize DOP and DEHP. A loam soil was incubated at 4, 10, 22 to 25 and 32C with DOP, DEHP and two other PAEs. Soil respiration rates were measured after 14 weeks, either with or without fresh additions of the PAEs. Increased rates of respiration, indicating microbial utilization of all the PAEs, were recorded. However, the results indicated that DOP and DEHP are used only marginally at 4 and 10C.
Nitrate and Chloride Accumulation and Distribution in Fertilized Tile‐Drained Soils
Authors: Gast R. G. , Nelson W. W. , MacGregor J. M.
Published: July 2010

Results of long term continuous corn studies on tile drained Webster loam in southwest Minnesota show that annual N applications up to 70% greater than N removed in grain are required for maximum yields. The object of the reported study was to establish the relative role of N incorporation into the soil organic matter and/or losses through denitrification, downward leaching, or tile drainage in determining the fate of this fertilizer‐N added above that removed in corn grain. Nitrate and chloride accumulations and distributions were determined in a Webster loam and Waldorf silty clay loam profiles after long term fertilization for continuous corn. Concentrations in the profiles were determined at 0.3 m depth intervals and at increasing distances from tile lines.

Maximum NO3−‐N accumulations accounted for less than half of the fertilizer‐N added but unrecovered in the corn grain. In contrast, Cl− accumulations in the soil profiles were approximately equal to that added, with little or no effect of distance from tile lines on either amounts present or on profile distribution: i.e. there was relatively little Cl− loss through tile drainage. Assuming Cl− and NO3− move with water at about the same rate, the results further suggest minimal loss of NO3−‐N in tile drainage. Since Cl− and NO3− concentration are small at depths greater than 3 m, downward leaching losses are apparently minimal leaving denitrification and/or incorporation into organic matter as the mechanisms largely responsible for disappearance of the unused fertilizer‐N. Denitrification is probably the main factor involved since similar experiments on well‐drained Minnesota soil showed little net incorporation of N into organic matter.
Effect of Nitrate and Sediment Constraints on Economically Optimal Crop Production
Authors: Onishi H. , Swanson E. R.
Published: July 2010

Crop systems and practices which are economically optimal in a 485.6‐ha (1,200‐acre) watershed with a planned recreational reservoir were determined under conditions of varying constraints on water quality in the reservoir. The technique of linear programming was used. Two requirements related to sedimentation and three requirements related to NO3−‐N concentration in the leachate below the root zone were considered. Thus, six combinations of restrictions on the choice of optimal crop systems were imposed. A system of charges for all sediment introduced into the reservoir substantially reduced erosion, irrespective of the limit placed on NO3−‐N concentration in the leachate below the root zone. Relaxation of the NO3−‐N limit from 10 mg/liter to no limit approximately doubled the net income above nonland costs.
Uptake of Inorganic Mercury by Bed Sediments
Authors: Kudo Akiro , Hart J. Sanford
Published: July 2010

The kinetics of uptake of inorganic mercury as mercuric chloride by a variety of freshwater river sediment types typical of Ottawa River sediments were studied to determine the influence of mercury concentration in water, hydrodynamic effects, sediment depth, aerobic or anaerobic conditions, and two types of water. Uptake appears to depend strongly on concentration of mercury in water and water velocity, and not on sediment depth or water type. No significant difference in uptake rates was observed between aerobic and anaerobic conditions during the 10 days studied.
Decomposition in Soil of Waste Cooking Oils Used in Potato Processing
Authors: Smith J. H.
Published: July 2010

Cooking oils used in potato processing are sometimes wasted in small quantities into the effluent that goes to land disposal. To determine the effect of this oil on land, palm and soybean oils were added to Portneuf silt loam at rates of 0.1, 0.5, 1.0, and 5.0 g oil in 100 g soil (2.2, 11.2, 22.4, and 112 metric tons/ha, respectively). Nitrogen was added and the mixtures were incubated at constant temperature in a CO2‐free continuously flowing air stream. Evolved CO2 was scrubbed from the air stream and decomposition calculated. Both oils decomposed at the same rate at each application rate. Maximum weekly decomposition was approximately 8 and 2.5 metric tons/ha for the 112 and 11.2 metric ton‐applications, respectively. There was no evidence for toxicity to the decomposition systems with the high application of oil and no evidence that difficulty would develop with land disposal of wastes containing these edible cooking oils.
Determination of Trace Metals in Sodium Dithionite‐Citrate Extracts of Soils and Sediments by Atomic Absorption
Authors: Jenne E. A. , Ball J. W. , Simpson C.
Published: July 2010

A general method has been developed for the analysis of Co, Cu, Ni, Mo, and Zn in dithionite‐citrate extracts of soils and sediments. Because of the high Zn content of dithionite, it is necessary to preclean the dithionite‐citrate solution before it is used to extract soils or sediments. This precleaning lowers the detection level significantly for other trace elements as well. Since Fe causes flame interferences in the determination of several first transition series elements by atomic absorption, the size of the individual sample aliquot taken to chelation‐solvent concentration is varied to provide a constant quantity of Fe (5,000 µg). The standards and blanks are adjusted to the same Fe content. This approach is necessitated by the wide differences in the Fe concentrations of the dithionitecitrate extracts. Following pH adjustments and addition of ammonium‐1‐pyrrolidine dithiocarbamate, the trace metals (and Fe) are concentrated via two successive 10‐ml methyl isobutyl ketone extractions. Quantities of Fe much greater than 5,000 µg interfere in the solvent concentration step. Natural organics released by the dissolution of free‐Fe and ‐Mn oxides, to the extent that they are represented by fulvic acids, do not cause any significant interference in the ammonium‐1‐pyrrolidine dithiocarbamate methyl isobutyl ketone extraction of the trace metals due to the releasing effect of the Fe present.
Phosphorus Associated With Sediments in Irrigation and Drainage Waters for Two Large Tracts in Southern Idaho
Authors: Carter D. L. , Brown M. J. , Robbins C. W. , Bondurant J. A.
Published: July 2010

Phosphorus was measured in irrigation and surface drainage waters for two large irrigation tracts, and inorganic, water‐soluble PO4‐P and total P inputs and outputs were computed. The present irrigation practices on both irrigation tracts conserve P by removing more P from the Snake River in irrigation water than is returned in drainage water. Even greater P conservation could be attained by implementing new practices. Approximately 90% of the P in waters diverted to irrigate the Northside Tract remained in the tract. About 50% of the amount diverted remained in the Twin Falls Tract. Particle size segregation takes place in some drainage streams and the finer sediments returning to the river contain higher total and NaHCO3‐extractable P concentrations than the soils from which they were eroded. The importance of defining sampling methods and procedures for P analyses is illustrated by comparative data on irrigation and drainage waters. The PO4‐P concentration in samples filtered through a 0.45 µm membrane filter was independent of the sediment concentration in waters, whereas the total P concentration of unfiltered samples was proportional to the sediment concentration.
Sediment in Irrigation and Drainage Waters and Sediment Inputs and Outputs for Two Large Tracts in Southern Idaho
Authors: Brown M. J. , Carter D. L. , Bondurant J. A.
Published: July 2010

Sediment inputs from Snake River irrigation water and sediment losses back to the river were measured for two large irrigated tracts in southern Idaho. There was a net sediment accumulation of 0.69 metric tons/ha onto the 65,000 ha Northside tract but a net sediment loss of 0.46 metric tons/ha from the 82,000 Twin Falls tract. Differences in sediment losses from the two tracts result from the difference in sedimentation in the drain‐ways of the two projects. Sediment deposited in drains on the Northside tract amounted to 4.5 metric tons/ha compared to 0.95 metric tons/ha for the Twin Falls tract. Drains on the Northside tract were constructed to grade whereas most drains on the Twin Falls tract are natural channels with steeper gradients. The net amounts of sediment eroded from farms within each tract were 4.0 metric tons/ha for the Northside tract and 1.42 metric tons/ha for the Twin Falls tract. This erosion loss from farms could be reduced within each tract by more careful use of water and construction of on‐farm sediment retention ponds. This would also reduce the amount of sediment returned to the river and lower costs of mechanically removing sediment from drains and canals. Construction of sediment retention ponds along main drains and reducing the amount of surface runoff returning to the river would also reduce the amount of sediment returning.
Ground‐Water Quality Related to Irrigation with Imported Surface or Local Ground Water
Authors: Nightingale H. I. , Bianchi W. C.
Published: July 2010

Ground‐water quality in an arid irrigated area that imports high quality surface water was compared with an adjacent up‐gradient area that uses local pumped ground water. A large irrigation canal separates the two areas which are up‐gradient from the pumping depression of the Fresno‐Clovis, California metropolitan area, which is dependent on ground water. Intensive sampling (154 wells) was done in the fall of 1972 after it was shown by previous sampling that the ground‐water electrical conductivity (EC), NO3−, and Cl− content had not significantly changed since 1967. Diagrammatic distribution maps for ground‐water quality showed great variability. The Wilcoxon‐Mann‐Whitney nonparametric statistical tests showed the significance probabilities for EC, NO3−, and Cl− differences above and below the canal were 0.093, 0.114, and < 0.00006, respectively. The significance of these differences are determined by the reader or decision‐maker by his chosen error probability, the error risk he is willing to take in rejecting the null hypothesis of no difference when it is true. Areas of higher ground‐water NO3− and Cl− were generally related to soil drainage‐recharge and agricultural use. The use of local ground water without supplemental surface supplies above the canal has led to ground‐water EC, NO3−, and Cl− concentrations to be 9.5, 18.6, and 91.8% higher, respectively, than below the canal which uses mostly high quality surface water.
Barriers to the Foliar Uptake of Lead
Authors: Arvik Jon H. , Zimdahl Robert L.
Published: July 2010

Cuticles of leaves and fruits were studied to determine the ability of these structures and their waxes to prevent movement of lead into the plant. Only extremely small amounts of lead could penetrate the cuticles, even after extended exposure. Removal of the waxes permitted increased penetration of some cuticles, and penetration seemed more related to species of plant than to thickness of the cuticle. Additionally, living plants were challenged by aerosols of lead bromochloride in an exposure chamber. Virtually all of the lead added to plants in this manner could be removed by chloroform rinse or mild acid washes, suggesting that the lead remained as a topical coating on the foliage. No significant amount of lead could be found in roots, fruit, or new shoot growth following exposure to lead aerosols.
A Simulation Model for Prediction of Herbicide Persistence
Authors: Walker Allan
Published: July 2010

A simulation model for prediction of herbicide persistence in the field is described. The model combines the effects of soil temperature and soil moisture content on the rates of herbicide loss, determined experimentally under controlled conditions, with the fluctuations in surface soil temperature and moisture content in the field. The computer program includes methods of simulating surface soil temperatures and moisture contents from standard meteorological data. In order to test the model, the degradation of napropamide (2‐(a‐naphthoxy)‐N,N‐diethylpropionamide) was examined. Under controlled conditions, loss of activity followed first‐order kinetics with half‐lives of 54, 63, and 90 days at 28C with soil moisture contents of 10.0, 7.5, and 3.5%, respectively. At 14C, half‐lives at 10.0 and 7.5% soil moisture were 102 and 112 days, respectively. When these data were used in the simulation model in conjunction with the relevant meteorological information, the patterns of loss of napropamide incorporated 2 to 3 cm in the field could be predicted. Napropamide was lost rapidly when applied to the soil surface, and since the model only takes into account losses through microbial or chemical metabolism, this could not be simulated. Some of the limitations and the potential benefit of the simulation technique for prediction of pesticide persistence are discussed.
The Effects of SO2 on in vitro Forest Tree Pollen Germination and Tube Elongation
Authors: Karnosky David F. , Stairs Gerald R.
Published: July 2010

The effects of SO2 on in vitro pollen germination and tube elongation were examined for Populus deltoides (Bartr.), Pinus resinosa (Ait.), Pinus nigra (Arnold), and Picea pungens (Engelm.). Comparisons were made between pollen fumigated in a dry condition and then placed on the germinating media, and moist pollen fumigated while on the germinating media.

Moist P. deltoides pollen germination was significantly reduced at SO2 concentrations of 0.75 ppm and above. Populus deltoides pollen tube elongation was more sensitive to SO2 exposure and highly significant decreases in tube length occurred at 0.30 ppm for 4 hours. Tube elongation decreased linearly with increases in SO2 concentration. Frequent bursting of pollen tubes occurred at SO2 concentrations greater than or equal to 0.3 ppm for 4 hours.

Exposure to SO2 caused similar effects on pollen germination and tube elongation for Pinus resinosa, Pinus nigra, and Picea pungens. Moist pollen was far more sensitive than dry pollen to SO2 exposure. A 4‐hour exposure to 1.4 ppm SO2 severely restricted moist pollen germination and tube elongation of the three conifer species. However, a similar exposure to 10 ppm SO2 had no effect on dry pollen of the three species.

Absorption of SO2 resulted in an acidification of the germination media. Germination trials on acidified media indicated that the resultant acidification could account for much of the reduced germination and tube elongation in P. deltoides but could not adequately explain the reduced conifer pollen germination and tube elongation.
Movement of Coliform Bacteria from Septic Tank Effluent through Selected Coastal Plain Soils of Virginia
Authors: Reneau R. B. , Pettry D. E.
Published: July 2010

Movement of total and fecal coliform bacteria form septic tank effluent through three Virginia Coastal Plain soils was monitored in situ over a 2‐year period. These soils were considered to be marginally suited for sanitary disposal of domestic wastes because of fluctuating seasonal water tables and/or restricting layers. Since septic effluent moved predominantly in a horizontal direction in these soils as a result of slowly permeable subsurface horizons, series of piezometers were installed to collect samples at selected distances and depths from the source (subsurface drainfield) in each of the soils studied. Generally, the most‐probable‐numbers (MPN) of both total and fecal coliforms decreased significantly with horizontal distance and depth. At the Varina location total and fecal coliform counts were observed to decrease from 11 and 1.3 × 106/100 ml in the distribution box to 11 and 2.5 × 103/100 ml at 6.1 m, respectively, above a relatively impermeable plinthic horizon. At the Goldsboro and Beltsville sites large reductions in both total and fecal coliform counts were noted within 13.5 m. Few detectable fecal coliform were present below the restricting layers at all three sites. On the basis of these results, it seems unlikely that coliform bacteria would move into the permanent ground water system.
Suspended Solids Carried by the Gallatin River of Southwestern Montana: II. Using Mineralogy for Inferring Sources
Authors: Klages M. G. , Hsieh Y. P.
Published: July 2010

Silt and clay carried in suspension by a mountain river in southwestern Montana were examined by X‐ray diffraction. Suspended sediment samples were collected from the river and its tributaries during spring snowmelt. In general the mineralogy of the sediment was related to geology of the drainage area but also differed between streams from similar geologic materials. Quartz gave the dominant diffraction peak in silts and smectite in clays from most of the streams. One tributary, Taylor Fork, was identified as the the chief source of suspended solids. The mineralogy of its silt and clay resembled that carried by the river on 8 of 10 sampling dates. Erosion of alluvial materials from the lower valley produced sediment with mineralogy similar to that presently carried by the river suggesting that the source of sediment has not changed much in recent geologic time. Branches of the tributary contributing the most sediment and of one other large tributary were examined. The branch contributing the most silt and clay to each could be identified from mineralogical measurements. An attempt to use crystallinity to determine if clays were eroded from surface soils was only partly successful.
Weathering of Accumulated Wastes in Unroofed and Unpaved Confined Livestock Operations
Authors: Chang A. C. , Adriano D. C.
Published: July 2010

Two unpaved outdoor livestock confinement units in southern California were sampled to determine the weathering and accumulation pattern of wastes on the ground surface after 2 months of waste accumulation. The result indicated that animal waste tended to accumulate in certain parts of the confinement area. It was found approximately 50% of the total waste produced was concentrated in 25% of the surface area. During the period of accumulation, waste underwent a 10–15% reduction of total solids apparently due to biological decomposition. The prevailing dry climate in the region has also limited the problem of waste accumulation to essentially that of odors and dusts. However, the samples collected indicated the accumulating waste was unstable and would undergo further decomposition at a suitable environmental condition. Moisture content, chemical oxygen demand, total nitrogen and chloride content of the waste samples were also determined. There appeared to be little difference in the weathering of accumulated wastes because of management operations at the two confinement units.
Effect of Sewage Sludge on Some Soil Physical Properties
Authors: Epstein Eliot
Published: July 2010

Raw and digested sewage sludges, 5% by weight, were incorporated into a Beltsville silt loam soil. The soil‐sludge mixtures were incubated at 15, 25, and 35C for 75 days. Periodic measurements were made on water retention, hydraulic conductivity, and aggregate stability. Adding sewage sludge shifted the water retention curve so that the water content at specific water potential values was higher, but the amount of water between −0.33 and −15 bars potential essentially remained the same as that of the original soil.

Addition of sewage sludge initially increased the saturated hydraulic conductivity. After 50 to 80 days, however, the hydraulic conductivity dropped to that of the original soil. Percent stable aggregates increased as a result of sludge addition. After 175 days, the percent stable aggregates averaged 28–35% for the sludgeamended soil, as compared to 17% for the original soil.
Effects of an Organic Arsenical Herbicide on a Salt Marsh Ecosystem
Authors: Edwards A. C. , Davis D. E.
Published: July 2010

The effects of single and repeat applications of monosodium methanearsonate (MSMA) on the standing crops of smooth cordgrass (Spartina alterniflora L.), a periwinkle (Littorina irrorata Say), and a rib mussel (Modiolus demissus Dillwyn) were investigated. Treatments applied were as follows: (i) single foliar application 90,000 ppm; (ii) 30 foliar applications of either 10,000, 1,000, 100, 10, or 0 ppm; and (iii) 30 floodings of enclosed areas of the salt marsh with 100 or 0 ppm MSMA. Post‐treatment sampling revealed: (i) no treatment altered the density of smooth cordgrass; (ii) 30 applications of 10,000 ppm decreased the dry weight living smooth cordgrass; (iii) flowering shoot production was reduced by 30 applications of 10,000 or 1,000 ppm; (iv) one application of 90,000 ppm and 30 applications of 10,000 or 1,000 ppm increased the percentages of dead and necrotic tissue on living shoots of smooth cordgrass and; (v) the periwinkle population was decreased by 30 applications of 10,000 ppm. None of the other treatments showed any significant effects on these parameters. Survival of the rib mussel was apparently not affected by flooding with 100 ppm in sea water. Arsenic levels in smooth cordgrass and soil samples were significantly increased by 30 foliar applications of 10,000 ppm or flooding 30 times with 100 ppm. Arsenic levels in periwinkles and rib mussels also increased immediately following these treatments with MSMA.
Metal Uptake by Barley Seedlings Grown on Soils Amended with Sewage Sludge
Authors: Dowdy R. H. , Larson W. E.
Published: July 2010

The removal of metals by 30‐day‐old barley seedlings (Hordeum vulgare L., cv. Traill) from two topographically associated soils having pH's of 5.9 and 7.9 (free carbonates) was studied following the application of 0, 3.8, 7.6, 15.2, and 30.4 tonne/ha of sewage sludge. One set of soil‐sludge samples were incubated for 1‐growing‐degree year before cropping to study the effect of sludge degradation on metal availability.

Total uptake of Zn, Pb, Ni, and Cr was greater from the sludge‐amended acid soil than from the calcareous soil. Incubation resulted in greater removal of Zn, Pb, Ni, and Cr from the acid soil. For the alkaline soil, incubation increased Cr uptake, but had no effect on Zn, Pb, Cu, and Ni uptake. In general, with the exception of Cu, metal uptake was greater from the incubated, acid soil‐sludge mixture than from a comparable nonincubated or alkaline mixture.

Sludge applications did not affect the amount of Ca and Mg extracted, but increased Na uptake. Conversely, the Ca and Mg concentration in barley tops decreased as the Na concentration increased with added sludge. The Fe concentration in the leaf tissue of seedlings grown on the acid soil was greatly depressed by the application of 30 tonne/ha of sewage sludge.
Effect of Long Term Land Disposal by Spray Irrigation of Food Processing Wastes on Some Chemical Properties of the Soil and Subsurface Water
Authors: Adriano D. C. , Novak L. T. , Erickson A. E. , Wolcott A. R. , Ellis B. G.
Published: July 2010

Food processing waste waters at two irrigated land disposal sites and subsurface waters (perched and ground waters) were monitored at daily to monthly intervals over one annual cycle of production. Soil profiles were sampled to depths up to 6.6 m in the early fall.

Yearly inputs were calculated at 487 kg/ha total N (Kjeldahl plus NO3‐N) and 101 kg/ha soluble PO4‐P (orthophosphate) from cannery wastes at site 1. Estimates for milk wastes at site 2 were 562 kg/ha total N and 522 kg/ha PO4‐P.

The range for NO3‐N in subsurface waters was 7 to 16 ppm at site 1 (perched water at 1.5 m) and 2 to 41 ppm at site 2 (ground water at 0.9 m). Maximum concentrations, found in summer, were essentially the same as the average for total N in the input wastes (16 ppm at site 1 and 38 ppm at site 2). Nitrate was stable in the percolation stream below the root zone. Annual additions to subsurface waters were estimated at 76% of input N at site 1 and 65% at site 2.

The range of PO4‐P in subsurface waters was 0.5 to 1.5 ppm at site 1 and 0.04 to 1.8 ppm at site 2; average waste water concentrations were 3 and 35 ppm. The highest concentrations in subsurface water were found in spring. Annual subsurface discharge was estimated at 27% of input P at site 1 and 2% at site 2. The extensive removals of PO4 and the similar concentrations encountered in subsurface waters are of theoretical and practical interest since PO4‐P had already accumulated in soil profiles at both sites in quantities which exceed the Langmuir maxima for nonirrigated control soils.

During seasons of major irrigation input, NO3 appeared in subsurface waters in concentrations exceeding public health standards; PO4 concentrations exceeded environmental guidelines at all times except where irrigation was discontinued during the winter at site 2.

Soil systems appeared poised to discharge at the observed rates because of the large quantities of organic N and fixed P which had accumulated in the profiles over 20 years operation at site 1, and 10 years at site 2. The rate of residual accumulation in soil could have been reduced by harvest, to extend system life materially. The harvest potential of three grass clippings per season removed for silage, was estimated experimentally at 31% of input N at both sites and 80% of input PO4 at site 1; 27% at site 2.
Land Application of Sewage Sludge: I. Effect on Growth and Chemical Composition of Plants
Authors: Sabey B. R. , Hart W. E.
Published: July 2010

Municipal sewage sludge was added to a Truckton loamy sand at rates of 0, 25, 50, 100, and 125 metric tons/ha (dry weight basis) in the field to determine the effect on the growth and chemical composition of plants. Severe inhibition of germination of sorghum sudangrass (Sorghum bicolor × S. sudanense) cv. NB 280S, and millet (Panicum miliacium L.) cv. Leonard, resulted when seeded shortly after the sludge was incorporated into the soil. Stand counts for wheat (Triticum aestivum L. em. Thell [aestivum gray] cv. Centurk) seeded about 3 months after sludge incorporation snowed no germination inhibition. Either the inhibitory factor was dissipated or the wheat was more tolerant than the other plants. The decrease in sorghum sudangrass yields with sludge addition was a result of poor germination rather than growth inhibition due to the sewage sludge. With one exception, yields on sludge‐treated wheat plots were greater or equal to the no‐sludge plots. Based on wheat yields, the optimum application rate of the sludge used in this study was between 25 and 50 metric tons/ha. sludge application except for lead and phosphorus. In no case, even at 125 metric tons/ha was the elemental content of the wheat grain outside normal ranges excepted in plant tissues.
Kinetics of Rice Straw Decomposition in Soils
Authors: Pal D. , Broadbent F. E.
Published: July 2010

Mature rice straw was decomposed in Sacramento clay and Stockton adobe clay at loading rates up to 8% of soil weight for 120 days. Carbon loss was linearly related to loading rate, and carbon loss at given loading rates was described by equations of the form C = ktm. Rice straw labeled with 13C and 15N added to the same two soils permitted distinction between straw and soil carbon and nitrogen during decomposition. A pronounced effect of straw on loss of soil carbon was observed, but the effects on soil nitrogen were small. Turnover times for the immature labeled straw were calculated to be between 0.8 and 3.4 years, depending on loading rate and soil. Priming ratios, defined as (soil C‐loss with straw) ÷ (soil C‐loss without straw) were greater than unity throughout the 120‐day period of incubation.
Utilization of the Pollutant Di‐2‐Ethylhexyl Phthalate by a Bacterium
Authors: Mathur S. P. , Rouatt J. W.
Published: July 2010

A bacterium, tentatively identified as the virtually ubiquitous saprophyte Serratia marcescens Bizio, was isolated for its ability to utilize the plasticizer di‐2‐ethylhexyl phthalate as sole source of carbon and energy. The organism was able to grow on o‐phthalic acid but not on 2‐ethylhexanol.

This strain of Serratia appeared to possess a constitutive esterase, but the enzyme(s) that mediated o‐phthalic acid utilization appeared to be adaptive. The isolate reported here should be useful in studies of the environmental dynamics of the pollutant phthalate esters, as well as for assessing the susceptibility of certain plastic materials to microbial attack.
Solar Ultraviolet Radiation in Terrestrial Plant Communities
Authors: Allen L. H. , Gausman H. W. , Allen W. A.
Published: July 2010

There has been a growing concern that NOx effluents from supersonic or other highflying craft, or chlorofluoromethane refrigerants or aerosol can propellents that diffuse to the stratosphere, could cause a reduction of atmospheric ozone, which would result in a concomitant increase of penetration of solar ultraviolet radiation to the earth's surface with possible biological consequences. Spectral distributions of direct‐beam and diffuse solar ultraviolet irradiance at the earth's surface, as a function of stratospheric ozone content and solar elevation angle, have been accurately measured or predicted by other researchers. Our objectives were to couple incident spectra to a plant canopy radiation penetration model to give the redistribution of middle ultraviolet radiation, or UV‐B (280–315 nm), within plant canopies. Detailed comparisons were made between two ozone content conditions (0.32 cm, typical for 30° N latitude and 0.24 cm, representing a 25% ozone reduction) with a 60° solar elevation angle.

Predictions of UV‐B radiation regimes in plant communities over ranges of architectural or structural characteristics, including erect‐leaf, normal‐leaf, and horizontal‐leaf canopies, were computed. Clumped, random, and regular leaf distributions were modeled, as well as leaf area indices of 2.6, 3.3, and 4.0. Phyloelement optical properties included zero transmissivity and 5% reflectivity. Soil reflectivities of both 5% and 20% were used. Epidermal transmission spectra were used to predict UV‐B radiation loads inside leaves.

Predicted penetration of UV‐B radiation was much greater in erect‐leaf than horizontal‐leaf canopies. Upward‐directed UV‐B irradiance was greater near the ground level than near the top of the canopy.

In conclusion, the model prediction described the range of UV‐B radiation regimes to be expected in plant communities under present stratospheric ozone content and under a 25% ozone reduction. Data from these idealized plant communities can be interpolated for other plant canopy types and soil types to predict upward or downward UV‐B radiation loads and dosages.
The Potential of Autocides and Microorganisms as Ecologically Acceptable Agents for the Regulation of Spruce Budworm Infestations
Authors: Weatherston J. , Retnakaran A.
Published: July 2010

The spruce budworm (Choristoneura fumiferana) is the most economically important indigenous pest in eastern North America. In order to protect valuable timber the budworm population must be restricted to endemic levels. To achieve this, and simultaneously attempt to improve environmental quality is a major objective of much research into the development of new insect control methods.

This review presents an encapsulated report of researches into the use of pheromones and hormones (autocides), and viruses, fungi, bacteria and microsporida (microorganisms) as possible control agents. Such agents would be more selective than conventional insecticides. Several of the control methods discussed in this report are almost operational, and while it is evident that none of them can completely replace chemical insecticides, field tests indicate that they have a potential in budworm control. The results also indicate the urgent need for testing the integrated use of the autocides and microorganisms, and the integrated application of these newer control agents with conventional chemical insecticides.
Denitrification in Subsoils of the North Carolina Coastal Plain as Affected by Soil Drainage
Authors: Gambrell R. P. , Gilliam J. W. , Weed S. B.
Published: July 2010

In a tiled moderately well‐drained soil, over 200 kg NO3‐N/ha were generally found distributed throughout the top 3 m. However, in a poorly drained soil, relatively low levels of NO3 were found in the top m and very little NO3 persisted in the saturated zone beneath 1 m.

Oxidation‐reduction potential (Eh) measurements in the tiled moderately well‐drained soil indicated well‐oxidized conditions (500–700 millivolts) to 3 m. The Eh measurements beneath 1 m in the poorly drained soil consistently indicated favorable conditions for denitrification. A marked decrease in the NO3‐N/Cl ratio with depth in the poorly drained soil supported the contention that denitrification was occurring in the soil.

The water‐soluble C content of the subsurface soil water was 2–5 mg/liter in the moderately well‐drained soil and 10–15 mg/liter in the poorly drained soil. The absence of saturated conditions for extended periods of time and lack of an adequate energy source apparently limited denitrification in the moderately well‐drained soil and much of the fertilizer N not utilized by crops moved into shallow aquifers and surface water. However, sufficient available organic C was present in the subsoil of the saturated, poorly drained soil to bring about a reducing soil environment and subsequent denitrification of the residual NO3. Thus, little NO3 moved from this soil into surface waters.
Nitrogen Losses from Soils of the North Carolina Coastal Plain
Authors: Gambrell R. P. , Gilliam J. W. , Weed S. B.
Published: July 2010

Nitrogen balances were measured for a moderately well‐drained and a poorly drained soil in the North Carolina Coastal Plain to evaluate the effect of drainage on the fate of unutilized fertilizer N. Approximately one‐half of the fertilizer N applied to each soil was not utilized by the crop.

Most of the nitrogen lost by surface runoff from both soils was organic nitrogen associated with the sediment. However, there was a measurable increase in loss of nitrogen from fertilized plots as compared to unfertilized plots. The poorly drained soil (27% organic matter) had approximately 50% less surface runoff than did the moderately well‐drained soil (2% organic matter). However, the concentration of N in runoff from the poorly drained soil was almost twice as great resulting in nearly identical N losses from the two soils. Much of the total surface loss of N from corn (Zea mays L.) occurred during the first few months after planting.

During the winters after the 1972 and 1973 harvests, an average of 46 kg NO3‐N/ha moved from the moderately well‐drained soil by subsurface drainage. A portion of this loss entered surface waters directly via tile outlets. The remainder was thought to enter a shallow aquifer and is believed to ultimately move with the water to nearby surface streams. It is unlikely that denitrification removed significant amounts of N from the moderately well‐drained soil.

An average of 16 kg NO3‐N/ha was removed from the poorly drained soil by subsurface drainage during the two winters. The smaller loss from the poorly drained soil was thought to result from denitrification of residual NO3 in the shallow ground water.
Salinity‐Ozone Interactive Effects on Alfalfa Yield and Water Relations
Authors: Hoffman G. J. , Maas E. V. , Rawlins S. L.
Published: July 2010

The effect of ozone on forage yield of alfalfa (Medicago sativa L. cv. Moapa) was determined at four controlled salinity levels. Plants were grown in gravel cultures in four environment‐controlled, sunlit chambers. Four salinity treatments (NaCl and CaCl2) having osmotic potentials of −40, −200, −400, and −600 kilopascals (kPa) were replicated four times in each chamber. Alfalfa grown in ozone‐free chambers was compared with plants exposed to ozone 2 hours every day between cuttings.

For nonsaline treatments, ozone at 10, 15, and 20 parts per hundred million (pphm) reduced forage yield by 16, 26, and 39%, respectively. As salinity increased, ozone had less effect on yield. Alfalfa exposed to 20 pphm of ozone for 2 hours daily yielded 25% more at −200 kPa osmotic potential than at the nonsaline level, −40 kPa. The residual effect of ozone treatments reduced yield in the next cutting. Salinity at all levels or ozone at 20 pphm increased water‐use efficiency of alfalfa; low concentrations of ozone had no effect on water‐use efficiency. Both ozone and salinity were required to increase leaf diffusion resistance; either factor alone had no effect.
Nutrient and Sediment Discharge from Agricultural Watersheds in Oklahoma
Authors: Olness Alan , Smith S. J. , Rhoades E. D. , Menzel R. G.
Published: July 2010

Seven cropland watersheds and four rangeland watersheds in central Oklahoma were monitored for surface hydrology and discharge of nitrogen, phosphorus, and sediment over a 1 year period. Precipitation and runoff were much above normal during the study. Sediment losses from the continuously grazed rangeland watersheds ranged from 18 to 23 metric tons/ha during the study. None of the sediment losses from the other watersheds exceeded 10 metric tons/ha.

Total nutrients discharged in runoff ranged from 2 to 15 kg/ha of N and 1 to 11.5 kg/ha of P. Flow‐weighted mean concentrations ranged from 1 to 6 ppm of total N, 0.2 to 1.9 ppm of nitrate‐N, 0.5 to 4.8 ppm of total P, and 0.04 to 0.9 ppm of soluble P. Runoff losses of soluble inorganic nitrogen were generally less than those quantities received in rainfall. Concentrations of soluble phosphorus in runoff from the cropland watersheds were much greater than from the rangeland watersheds. Losses of fertilizer nitrogen and phosphorus did not exceed 5% of the most recent applications, although surface runoff was 4‐ to 10‐fold greater than that observed in previous years.
Comparison of Methods for the Determination of Total Phosphorus in Waters Containing Particulate Material
Authors: O'Connor P. W. , Syers J. K.
Published: July 2010

Perchloric acid digestion compared favorably with Na2CO3 fusion for the determination of total P in a range of waters containing varying concentrations of both P and particulate material. The recovery of particulate P by persulfate digestion tended to decrease with increasing particulate material concentration in both natural unfiltered samples and in filtered samples to which particulate material was added. Recovery of added soil particulate P by persulfate digestion also decreased with increasing particle size. Low recovery of P by persulfate digestion was caused by the incomplete extraction of P occluded within oxides and hydrous oxides of iron. Between 58 and 86% of the P not recovered by persulfate digestion was in the inorganic form. Persulfate digestion is not recommended for the determination of total P in waters containing particulate inorganic materials of soil origin. Perchloric acid digestion is considered to be a more suitable method for such samples.
Identification of Sulfur Gases Evolved from Animal Manures
Authors: Banwart W. L. , Bremner J. M.
Published: July 2010

Evolution of volatile sulfur compounds from animal manures [beef cattle (Bos taurus), dairy cattle (Bos taurus), poultry (Gallus domesticus), sheep (Ovis aries), and swine (Sus scrofa)] was studied by gas chromatographic techniques permitting detection and identification of trace (nanogram) amounts of sulfur gases in the presence of nonsulfur gases known to be released through microbial decomposition of organic materials. All manures studied released hydrogen sulfide (H2S), methyl mercaptan (CH3SH), and dimethyl sulfide (CH3SCH3) when incubated under anaerobic conditions, and some released dimethyl disulfide (CH3SSCH3), carbonyl sulfide (COS), and/or carbon disulfide (CS2). Only trace amounts of one sulfur gas (dimethyl sulfide) could be detected in the gaseous products of decomposition of manures under aerobic conditions, and no evidence could be obtained that sulfur gases contribute to the odors of dried manures. Most of the sulfur volatilized when manures were incubated under anaerobic conditions was in the form of hydrogen sulfide and methyl mercaptan, and the amount of sulfur volatilized in 1 month at 23C represented < 1% of the total sulfur in the manures studied.
Absorption and Translocation of Sulfur Dioxide by Seedlings of Four Forest Tree Species
Authors: Jensen K. F. , Kozlowski T. T.
Published: July 2010

Rates of absorption of SO2 and of translocation of absorbed sulfur were determined in sugar maple (Acer saccharum Marsh.), bigtooth aspen (Populus grandidentata Michx.), white ash (Fraxinus americana L.), and yellow birch seedlings [Betula alleghaniensis Britton (Betula lutea Michx. f.)]. Bigtooth aspen, a sensitive species, had the highest absorption rate with no prefumigation and sugar maple, a tolerant species, had the lowest. After 20 hours or more of prefumigation with 1,965 µg/m3 (0.75 ppm) SO2, the rate of sulfur absorption was reduced in all species except white ash, a species intermediate in sensitivity. The relationship between species sensitivity and absorption rate thus changed with the prefumigation treatment. The foliar sulfur content of all species increased with SO2 fumigation. Sulfur‐35 absorbed from the atmosphere as 35SO2 was concentrated mainly in the leaves shortly after fumigation, but by the eighth day had been translocated throughout the plants. Amounts of sulfur translocated to roots varied with species.