bluuebunny/crossref_metadata_2025 huggingface dataset:
Escape of Elemental Phosphorus from Soil when Applied as White Phosphorus or the Phosphorus‐Sulfur Eutectic Solution
Authors: Warnock R. E.
Published: July 2010

When molten white phosphorus was applied to soil and not adequately covered, oxides of P issued from the soil surface. The escape of P from soil fertilized with pellets of white phosphorus or the eutectic solution of P4‐S8 was determined. Most of the P recovered from the atmosphere was P4 rather than oxides, furthermore, P4 escape was considerably greater from phosphorus applied as the P4‐S8 eutectic solution than from pellets of white phosphorus. The escape of P4 from the eutectic solution also persisted longer than from a like application of white phosphorus. No appreciable difference was found in phosphorus escape from a calcareous soil as compared to that from an acid soil. Phosphorus escape was reduced by deeper placement, but was not prevented by placement at a depth of 10 cm or by increased soil moisture levels up to field capacity. Phosphorus sulfides applied to soil did not release phosphorus as did the eutectic solution of P4‐S8. Calculations suggest that hazardous levels of P4 might accumulate in the air above fields fertilized with the P4‐S8 eutectic solution.
Arsenic Toxicity to Cotton and Soybeans
Authors: Deuel Lloyd E. , Swoboda Alien R.
Published: July 2010

Arsenic toxicity levels for ‘Lankert’ cotton (Gossypium hirsutum L.) and ‘Patterson’ soybeans (Glycine max L. merr.) were determined in a green house experiment using an Amarillo fine sandy loam and a Houston Black clay. The treatments ranged from 28 to 280 kg As/ha in the Amarillo soil and from 56 to 560 kg As/ha in the Houston Black soil. The vegetative cotton yields were significantly decreased below the checks at the 56 and 280 kg/ha rates of applied As in the Amarillo and Houston Black soils, respectively. Soybeans were found to be more sensitive to As than cotton. Vegetative soybean yields were significantly decreased at the applied rates of 28 kg As/ha in the Amarillo soil and 168 kg As/ha in the Houston Black soil. Yield limiting As concentrations in plant tissue were 4.4 ppm and greater in cotton, and 1 ppm and greater in soybeans. Water soluble As levels of 8 ppm in the Amarillo soil and 28 ppm in the Houston Black soil were required for a significant decrease in the vegetative growth of cotton. The water soluble As levels detrimental to soybeans were 3 and 12 ppm in the Amarillo and Houston Black soils, respectively.
Suitability of Freezing as a Method of Preserving Runoff Samples for Analysis of Soluble Phosphate
Authors: Nelson D. W. , Römkens M. J. M.
Published: July 2010

Slow freezing of surface runoff samples decreased the levels of soluble orthophosphate in the water phase from 2 to 27%, but low temperature storage at 2C for 3 days or freezing of the water phase after sediment removal did not alter the orthophosphate concentrations of samples. Rapid freezing of runoff samples in liquid nitrogen resulted in decreases in orthophosphate content which were about one‐half of those observed for conventional freezing. Frozen storage is not a good method for preserving runoff samples to be analyzed for soluble phosphate unless sediment is removed prior to freezing.
Economic Impact of Restricting Herbicide Use
Authors: Fox Austin S.
Published: July 2010

The economic impact of restricting herbicide use is directly related to their real benefits. Farmer and consumer benefits from using herbicides are associated with the differences between a production function in which herbicides are used to control weeds and a similar but lower function for combinations of alternative weed control practices—not including herbicides. The lower function shows production without herbicides for the same dollar value of alternative resources—primarily land and labor. It also shows the additional dollar value of the alternative resources needed to get the same production when herbicides are not used. The latter is implicit in evaluating costs of restricting specific herbicides while maintaining production. In one study, it was estimated that banning the use of 2,4,5‐T on 8 million acres of farm and nonfarm land in 1969 would have increased costs to farmers about $32 million, assuming current levels of production were maintained. However, if substitutes for 2,4,5‐T could not include the related phenoxy herbicides, it was estimated that additional costs to farmers as a result of replacing 2,4,5‐T would have been $44 million. In a related study it was determined that restricting the use of all phenoxy herbicides would increase United States farmers production costs about $290 million. In addition about 20 million more hours of family labor would be used and about 6 million more crop acres would be required.
Soil Absorption of Air Pollutants
Authors: Bohn Hinrich L.
Published: July 2010

Soil emits some, but absorbs many, air pollutants. The net effect of the soil is to reduce air pollution by absorbing air pollutant gases and particulate matter and converting them into less harmful forms, forms unavailable to plants and nutrients. The gases emitted by soils, such as H2S, N2O, CH4, and CO, are products of reactions largely outside of man's control and are natural parts of the carbon, nitrogen, and sulfur cycles.

Soils absorb organic gases faster and in greater amounts with increasing molecular weight and with increasing number of nitrogen, phosphate, oxygen, sulfur, and other functional groups in the compound. The absorption of lower‐molecular weight and less‐substituted organic gases depends upon the buildup of an appropriate microbial population.

The absorption of inorganic air pollutants by soils is primarily by chemical and physical means. Many of the air pollutant gases oxidize after being absorbed and produce acidity which is countered by the pH‐buffering capacity of the soil.

Soils are also a source and the major absorbent of siliceous particulate matter in air. Heavy metal, fluoride, and other pollutant aerosols are absorbed and rapidly rendered unavailable to plants. The extent of unavailability of most absorbed elements increases with soil pH. The inactivation of heavy metals by soils is approximately Cu > Pb > Zn > Cd > Ni.
Organic Compounds in Soil Water of Some Ultisols of the Atlantic Coastal Plain
Authors: Nettleton W. D. , McCracken R. J.
Published: July 2010

Water samples collected from undisturbed, uncultivated, forested soils of the Atlantic Coastal Plain in Wilson County, North Carolina, were analyzed for content and composition of natural organic substances. Sugars, organic acids, and polyphenols were detected. These results should be useful “baseline data” for comparison with water in and from soils to which agricultural chemicals and organic wastes have been added.
A Simple Digestion Procedure for Estimation of Total Nitrogen in Soils and Sediments
Authors: Nelson D. W. , Sommers L. E.
Published: July 2010

A simple and convenient digestion procedure for total N analysis of soils and sediments is described. The digestion is carried out in pyrex Folin‐Wu tubes heated in an aluminum block placed on a hot plate. Samples up to 1 g in size may be used and a digestion time of 3 hours after clearing is adequate. The proposed and conventional semimicro‐Kjeldahl methods gave essentially the same values for total N in a wide variety of soils and sediments. The precision of the proposed method was almost as good as those reported for other semimicro‐Kjeldahl methods. The tube digestion method allows simultaneous digestion of 60 samples in a relatively inexpensive and maintenance‐free aluminum heating block, which occupies a minimum of laboratory space and appears applicable for routine determination of total N in soils having diverse properties.
Concentrations of Nitrogen, Phosphorus, Potassium, and Total Soluble Salts in Soil Solution Samples from Fertilized and Unfertilized Histosols
Authors: Hortenstine C. C. , Forbes R. B.
Published: July 2010

Lake Apopka, in central Florida, ranked at one time among the most productive bass and panfish bodies of water in the United States. During recent years this lake became highly eutrophic and fishing declined drastically. Farming operations on the rich organic soil along the northern shore of the lake were implicated as one cause of this eutrophication.

In an attempt to measure agriculture's contributions to the nutrient concentration in the lake, soil solution samples were extracted from uncleared, swampy Everglades mucky peat; newly cleared, drained Everglades mucky peat; and Everglades mucky peat that had been under cultivation for approximately 15 years. Nitrate‐N, orthophosphate P, and K concentrations were relatively low in soil solution samples from the swampy area. Concentrations of each nutrient in soil solution extracted at the 60‐cm depth in the newly cleared area increased by as much as 8 to 12 times as compared to the 60‐cm depth in the swampy area. Further increases were noted in the cultivated area. Indications were that the peat itself was a heavy contributor of nutrients to the drainage water.
Chemical and Biochemical Considerations for Maximizing the Efficiency of Fertilizer Nitrogen
Authors: Parr J. F.
Published: July 2010

Fertilizer nitrogen is subject to loss from the soil‐root zone, and immobilization by the soil and rhizosphere microfloras, which can result in low recovery and use efficiency of the applied nitrogen. With increasing rates of application, fertilizer nitrogen efficiency decreases progressively, while leaving an increasing amount of unused nitrogen as a potential pollution hazard. Since the point of greatest economic return from this nutrient is usually somewhere below the point of maximum yield, it should be possible to adjust fertilizer nitrogen rates for maximum return and minimum loss to the environment. This can be achieved through improved soil and crop management practices, including proper timing of application of conventional nitrogen fertilizers and use of deep‐rooted crops for recovery of leached nitrate. A rational approach to more meaningful nitrogen recommendations is needed, one which would account for residual fertilizer nitrogen and mineralizable soil nitrogen, and allow an accurate prediction of the amount of supplemental fertilizer nitrogen necessary to produce the desired yield. Efficiency of fertilizer nitrogen might also be increased with controlled release fertilizers, including the use of coated granules, and compounds of limited water solubility blended with conventional nitrogen fertilizers, to achieve a specific release rate coincident with the nitrogen requirements of a crop. Formulation of ammoniacal fertilizers with nitrification inhibitors offers considerable opportunity for increasing fertilizer nitrogen efficiency.
Movement of Nitrate Nitrogen in Some Grassland Soils of Southern Alberta
Authors: Sommerfeldt Theron G. , Smith A. Douglas
Published: July 2010

The downward movement of NO3‐N in dryland soils under native grass [Agropyron smithii Rydb., Bouteloua gracilis (HBK.) Lag., and Stipa comata Trin. & Rupr.] 6 to 8 years after N was applied at rates up to 976 kg/ha reached a depth of 180 cm. Phosphorus fertilizer did not affect NO3‐N movement. Under seeded grasses, there was no evidence of NO3‐N accumulation 2 years after a single application of N at rates up to 944 kg/ha. After repeated annual applications of N that totaled up to 3776 kg/ha over a 4‐year period, NO3‐N accumulations were found to depths of 90 to 120 cm. The depth of NO3‐N movement under bromegrass (Bromus inermis Leyss.) was similar to that under crested wheatgrass [A. cristatum (L.) Gaertn.], but more NO3‐N accumulated in the soil under the bromegrass. In irrigated soil underlaid by drains, NO3‐N leaching was greater in a loam soil over till growing a mixture of bromegrass and alfalfa (Medicago sativa L.) than in a loam soil over sandy loam‐loamy sand growing an irrigated pasture‐grass mixture [A. elongatum (Host) Beauv. and Festuca arundinacea Schreb.]. These studies indicate that, with good management, fertilizer N on grassland soils is not an important contributor to pollution in semiarid southern Alberta.
Persistence and Microbiological Effects of Acarol® and Chlorobenzilate in Two Florida Soils
Authors: Wheeler W. B. , Rothwell D. F. , Hubbell D. H.
Published: July 2010

The influence of the miticides Acarol® (benzilic acid, 4,4′‐dibromo‐isopropyl ester) and chlorobenzilate (benzilic acid, 4,4′‐dichloro‐ethyl ester) on nitrification capacity and relative microbial numbers in Lakeland and Leon fine sands was determined. Since chlorobenzilate is now used commercially and a proposal is pending for the registration and sale of Acarol®, it is important to assess the effects of these materials on soil microbial populations.

The miticides were applied to Lakeland and Leon fine sands at rates of 0, 0.25, 0.50, and 1.0 ppm, incubated in the laboratory for 16 weeks, and sampled for analysis at periodic intervals.

Neither chemical influenced the nitrification capacity of either soil or the numbers of fungi, bacteria, and actinomycetes. Acarol® was more persistent than chlorobenzilate; both chemicals remained at higher levels for longer periods of time in Leon soil than in Lakeland soil. The miticides had finite rates of disappearance from both soils.
Chemical Distribution of Residual Fertilizer Nitrogen in Soil as Revealed by Nitrogen‐15 Studies
Authors: Allen A. L. , Stevenson F. J. , Kurtz L. T.
Published: July 2010

Chemical distribution patterns were obtained for the residual N in field plots previously amended with 15N‐labeled urea and oxamide. From 25 to 40% of the fertilizer N was present in the soil (0 to 25 cm) after the first growing season, about half of which still remained after 5 years. Essentially all of the fertilizer‐derived N (97.0%) occurred in organic combination; only a small fraction (3.0%) was accounted for in inorganic forms, chiefly as fixed NH4+. In comparison to the native humus N, higher percentages of the fertilizer N left after the first growing season occurred as amino acids (52.0 vs. 33.7%) and amino sugars (8.2 vs. 7.5%); lower percentages occurred in acid‐insoluble forms (9.0 vs. 15.2%), as acid‐hydrolyzable organic NH3 (9.0 vs. 17.0%), and as unidentified acid‐soluble N (8.8 vs. 20.3%). Considerable humification occurred during the subsequent 4 years with relocation of amino acids N (and possibly amino sugar‐N) to more resistant humus forms. The findings suggest that fertilizer N, once incorporated into soil organic matter, becomes increasingly stable with time and is not readily mineralized or subject to leaching.
Chlorodioxins in Pesticides, Soils, and Plants
Authors: Helling C. S. , Isensee A. R. , Woolson E. A. , Ensor P. D. J. , Jones G. E. , Plimmer J. R. , Kearney P. C.
Published: July 2010

Chlorodioxins, such as 2, 3, 7, 8‐tetrachlorodibenzo‐p‐dioxin (TCDD), are highly toxic impurities found in certain pesticides. A review is made of (i) the sources and toxicology of TCDD and its relationship to the herbicide 2,4,5‐trichlorophenoxyacetic acid (2,4,5‐T), and (ii) pesticide analyses and soil‐related environmental studies of TCDD conducted by the U. S. Department of Agriculture. TCDD was persistent and immobile in soils. The dioxin was not detected, however, 6 years after abnormally high applications of 2,4,5‐T to Lakeland sand. TCDD was not photodegraded on soil and only slightly, in aqueous suspension. Plants grown in soil containing 0.06 ppm TCDD had no detectable quantity (⩽ 1 ppb) at maturity. It was not translocated when applied to leaves, but wash‐off or volatilization occurred. TCDD was undetected (< 50 ppb) in 19 bald eagle (Haliaeetus leucocephalus) carcasses.
An Economic Analysis of Selected Agricultural Uses of Warm Water in the Pacific Northwest Resulting from Electric Power Generation,
Authors: Johns R. W. , Folwell R. J. , Dailey R. T. , Wirth M. E.
Published: July 2010

Between 1970 and 1990, 85% of all new electric power generating capacity is estimated to require water for cooling. This poses a question for research scientists from several disciplines of finding some productive use for the waste water required by steam generating plants. Since there is usually a finite amount of water available for cooling purposes adjacent to the plant sites, the problem becomes one of finding an economic use for a scarce resource. Several possibilities are discussed for making use of waste water: aquaculture, soil heating, and greenhouse heating.

Two alternatives were considered for using cooling reservoirs (i) the production of carp for feed or fish meal, and (ii) catfish for the fresh market. Soil warming and greenhouse heating would involve locational problems relative to plant production, processing facilities, and transportation.

None of the uses studied showed clear‐cut advantages in terms of profits which would attract economic investment. The price of carp must be greater than $59.52/metric ton to pay for the rental costs; the current market price ranges from $55 to $60/metric ton. The market demand for catfish has been overestimated and prices have been declining for the past 5 years. Using a 607‐ha (1,500‐acre) cooling pond, the market price for catfish would have to be $.44/kg ($.20/lb) or the enterprise would not pay for the use of the facilities. Catfish prices for 1970–71 were $.57/kg ($.26/lb); further increases in production in the southern USA will likely cause even lower prices. Relocating greenhouses in order to use warm water for heating appears to be a marginal investment. The size of soil‐warming systems is limited by the high initial investment, estimated yield response, and vegetable prices. A soil‐warming technique costing only $4,942/ha ($2,000/acre) to install would be profitable for 20 or 29 vegetable crops considered; an investment cost of $12,355/ha ($5,000/acre) would be profitable for only 1 of the 29 crops considered.
Effects of MCPA Applied to Successive Generations of Flax
Authors: Comstock V. E. , Ford J. H.
Published: July 2010

Application of high rates of [(4‐chloro‐o‐tolyl)oxy] acetic acid (MCPA) on four relatively homogeneous populations of flax (Linum usitatissimum L.) for seven successive generations and on two heterogeneous populations for three successive generations (F2, F2, and F4) caused no detectable genetic change in yield, oil content, iodine value, or maturity. Tolerance to MCPA was not increased by successive generation treatment with MCPA.

The lack of detectable mutants in the progenies of flax populations sprayed with high rates of MCPA for several successive generations suggested that MCPA was not mutagenic. The frequency of mutations should not be increased as a result of successive applications of MCPA to commercially grown flax cultivars or to breeding populations.
Effects of Treated Municipal Wastewater on Oat Forage and Grain
Authors: Day A. D. , Kirkpatrick R. M.
Published: July 2010

Experiments were conducted at Tucson, Arizona to study some effects of treated municipal wastewater on growth, yield, and quality of oats (Avena sativa L.) grown for pasture forage and grain. No differences were observed in plant height, tillers per plant, green forage yield, and total protein between forage grown with well water plus suggested amounts of N, P, and K and forage grown with wastewater alone. Oats produced more dry forage when grown with well water plus suggested N, P, and K than when irrigated with wastewater. Wastewater produced forage with higher moisture content than well water plus N, P, and K. When grown for forage, cultivars differed in plant height, dry forage yield, and total protein content.

Oat grain data showed no differences between irrigation and fertilizer treatments for maturity, plant height, panicles per unit area, grain yield, and total protein. Well water plus suggested N, P, and K resulted in fewer seeds per panicle and heavier seeds than wastewater. Cultivars differed in maturity, plant height, panicles per unit area, seeds per panicle, seed weight, grain yield, and total protein. Treated municipal wastewater can be utilized to produce oats with grain yields and forage and grain protein contents approximately equal to those obtained when oats are grown with well water and suggested levels of N, P, and K.
Pesticide Volatilization as Related to Water Loss From Soil
Authors: Spencer W. F. , Cliath M. M.
Published: July 2010

Results of experiments to determine the relationship between pesticide volatilization and water loss from soil indicate that volatilization rate is controlled by diffusion of the pesticide and by mass flow of water to the soil surface. Volatilization of soil‐incorporated lindane and dieldrin was measured under conditions whereby the soil surface remained relatively moist while the humidity of the air passing over the soil was varied to regulate water loss from the soil. Water loss accelerated pesticide volatilization rate, but only after the soil surface had been depleted of the pesticide, indicating that the enhancement was due to the “wick effect,” whereby pesticides move to the soil surface by mass flow in water moving to the surface to replace that evaporated, and not due to the mechanism called “codistillation.” There was good agreement between measured increases in volatilization rates and calculated amounts of lindane or dieldrin moving to the soil surface in evaporating water. Lindane is more water soluble than dieldrin and its volatilization was more enhanced by concurrent evaporation of water from the soil surface. At very low relative humidities, dieldrin accumulated at the soil surface; this resulted in rapid volatilization when the surface was again moistened by exposure to a relative humidity of 100%. Results indicate that pesticides carried to the surface in evaporating water will volatilize, either immediately or after remoistening the soil surface following drying. Desorption isotherms relating soil pesticide concentrations to soil solution concentrations should be useful in predicting volatilization rates associated with evaporating water.
Effect of Detergent Application on the Growth of Corn
Authors: Judy J. N. , Martens D. C. , Kroontje W.
Published: July 2010

A greenhouse experiment was conducted to determine the effects of two detergents on the growth of corn (Zea mays L.) on Davidson clay loam and Norfolk fine sandy loam. A heavy‐duty non‐enzyme detergent (Bz) and a heavy‐duty enzyme detergent (Tx) were applied to the soils in watering solutions at concentrations of 0, 20, 800, 1,600, 4,800, 8,000, 10,000, 12,000, and 14,000 ppm. Stimulations in growth occurred on the Davidson soil that received the 1,600 ppm Bz or the 800, 1,600, 4,800, and 8,000 ppm Tx solutions and on the Norfolk soil that received the 800 ppm Tx solution. These stimulations were attributed to responses to P contained in the detergents. Yield decreases occurred on the Davidson soil that received solutions containing 8,000 through 14,000 ppm Bz or 14,000 ppm Tx, and on the Norfolk soil that received solutions containing 1,600 through 14,000 ppm Bz or 4,800 through 14,000 ppm Tx. These yield decreases were attributed to soluble salt damage from the Na salts contained in the detergents on all treatments, except where Tx was applied to the Norfolk soil. In the latter case, specific Na salts effects could not be separated from general salinity effects. Plants grown on the Davidson soil were more tolerant to detergent applications than those grown on the Norfolk soil, probably because of the greater salt retention of the former soil. It was concluded that the changes in soil pH and B availability due to detergent applications were not responsible for the yield decreases in this study.
Pelletized Municipal Refuse Compost as a Soil Amendment and Nutrient Source for Sorghum
Authors: Hortenstine C. C. , Rothwell D. F.
Published: July 2010

The handling, processing, and disposal of solid waste have reached such proportions in the USA as to constitute one of our major environmental problems. Over 480 million metric tons of solid waste are discarded annually by American citizens. In the past, most of this waste was burned in open dumps or deposited in mismanaged landfills. Because of air and water pollution, more satisfactory methods must be developed for solid waste disposal. Composting with efficient machinery under sanitary conditions shows promise in helping to solve this problem. The end product of composting has value as a soil amendment and contains nutrients which are available for plant use. The objective of this study was to evaluate a pelletized compost of much improved physical conditions as compared to other composted municipal refuse.

Pelletized compost was used in a greenhouse study as a soil amendment and plant nutrient source after incorporation in Arredondo sand. The application of 8 metric tons/ha of compost increased the yields of two sorghum (Sorghum bicolor L. Moench) crops as compared to the control. Also, the highest rate of compost (64 metric tons/ha) produced higher yields as compared to 10‐4.4‐8.3 fertilizer at 2 tons/ha. Uptake of all plant nutrients measured, except for Mn, was increased by compost applications. In addition, water retention and cation exchange capacity of the Arredondo sand were generally increased by compost applications.
Oxygen Utilization in Soils Flooded with Sewage Water
Authors: Lance J. C. , Whisler F. D. , Bouwer H.
Published: July 2010

Diffusion and mass flow were important mechanisms of oxygen transport in soil columns intermittently flooded with sewage water. The amount of oxygen entering the soil by mass flow during drainage was 30 to 40% of the total amount entering the soil. Most of the estimated available oxygen was used in the oxidation of NH4+ to NO3−. Enough oxygen entered the soil during a 5‐day dry period to oxidize all of the nitrogen applied when the soil was flooded for 6 days with secondary sewage effluent containing 20 mg/liter of NH4‐N at an infiltration rate of 50 cm/day. Application of NH4+ in excess of that which could be oxidized during the dry period resulted in a gradual increase in the NH4+ concentration of the reclaimed water. An increase in NH4+ concentration can be prevented by balancing the NH4‐N applied against the oxygen entered during the dry period.

Most of the oxygen entered the columns during the first 3–4 days of the dry period. Thus the amount of oxygen entering the soil can be increased more effectively by increasing the frequency rather than the length of the dry periods.

The soil profile remained in a reduced state below the 140‐cm depth during a 10‐day dry period. This showed that NH4+ stored below this depth would not be nitrified and that an environment favorable for denitrification was maintained in part of the profile at all times. Anaerobic reactions were as effective as aerobic reactions in reducing the chemical oxygen demand (COD) of sewage water from 50 to 18 mg/liter.
Cadmium Content of Soybeans Grown in Sewage‐Sludge Amended Soil
Authors: Jones Robert L. , Hinesly T. D. , Ziegler E. L.
Published: July 2010

Disposal of municipal sludge on cropland raises the question of availability to plants of Cd which is often much more concentrated in sludges compared to native levels in soil. In a greenhouse experiment, Cd added in a factorial design with heated anaerobically digested sewage sludge and Cd acetate as factors was readily available to the soybean plant (Glycine max L.) where it was translocated to aerial parts, accumulating up to 18 ppm in the mature plant. Incremental additions of sewage sludge tended to depress the Cd levels observed in the mature plant and seed. Cd contents in the plant at harvest and in seed were directly related to soil levels extractable by 0.1/V HCl. Seed levels of about 1.0 ppm Cd produced by application of 144 metric tons/ha of sludge solids were not within toxic limits reported in the literature.
Nitrogen‐15 Enrichment of Soils and Soil‐Derived Nitrate
Authors: Bremner J. M. , Tabatabai M. A.
Published: July 2010

Nitrogen‐isotope analysis of soils and soil‐derived nitrate showed (i) that there is considerable variation in the 15N enrichment (Δ 15N) of the nitrate nitrogen produced on aerobic incubation of different soils and (ii) that the Δ 15N of this nitrate nitrogen depends upon the time of incubation and can differ markedly from that of the total soil N. The data reported illustrate the impracticability of a recently proposed method of assessing the contribution of fertilizers to nitrate in surface waters that requires measurement of the natural 15N enrichment of soil‐ and fertilizer‐derived nitrate.
An Open‐Top Field Chamber to Assess the Impact of Air Pollution on Plants
Authors: Heagle Allen S. , Body Denis E. , Heck Walter W.
Published: July 2010

Reasonable air pollution control policies depend upon a comparison of the costs of air pollution losses with the costs of controls. Present estimates of national economic losses to agricultural and ornamental vegetation are based primarily on field observations and partially on growth and yield data obtained from closed‐top field chambers and greenhouses. This research describes the design and evaluation of an open‐top field chamber that was developed to provide an environment more closely resembling ambient conditions than the environment found in closed‐top chambers.

Temperature and relative humidity within open‐top chambers were similar to ambient conditions. Direct sunlight reached the plants for a portion of each day and rain entered, although not always uniformly over the chamber base. Chambers receiving charcoal‐filtered air protected sensitive ‘Bel W3’ tobacco plants (Nicotiana tabacum L.) from ambient ozone concentrations. Plants growing in chambers receiving unfiltered air or in ambient air plots were severely injured.
A Cylindrical, Open‐Top Chamber for the Exposure of Plants to Air Pollutants in the Field
Authors: Mandl R. H. , Weinstein L. H. , McCune D. C. , Keveny Monica
Published: July 2010

Much of the information on the effects of air pollutants on plant life has been derived from studies with controlled‐environment, greenhouse, and field fumigation equipment. Each of these is important for the gaining of conditional information on the response of plants to air pollutants, but none of them can simulate ambient environmental conditions. Portable and fixed field fumigation chambers have perhaps come the closest to providing the ambient milieu, but the usual closed design alters normal conditions of light intensity and quality, temperature and humidity fluctuations, precipitation, and free access of insects and plant pathogens.

A simple, relatively inexpensive, and light‐weight open‐top chamber of modular design has been built and tested. Each module is 1.22 m (4 feet) high and 2.74 m (9 feet) in diameter, and can be stacked vertically in combinations of 1, 2, or 3 modules. The modules are fabricated from corrugated fiberglass panels attached to aluminum hoops and the air‐delivery plenum from lay‐flat polyethylene tubing. A mobile air filter and blower assembly provides air that has passed through a dust filter and an activated‐charcoal filter. An open plastic mesh placed across the top of the chamber reduces the influence of wind on the air distribution system, but it does not impede the entrance of precipitation or of insects.

The chamber was tested in several ways: (i) efficiency of the chamber and filter‐blower assembly for exclusion of ambient oxidants was tested by monitoring the atmosphere and by growing susceptible plants in chambers with or without charcoal filters and in outside plots; (ii) distribution and concentration of an introduced pollutant within the chamber were measured by a dynamic air monitoring method; and (iii) accumulation of an introduced pollutant was studied with both plants and a static monitoring method.
Salinity‐Ozone Interactions on Pinto Bean: Integrated Response to Ozone Concentration and Duration
Authors: Maas E. V. , Hoffman G. J. , Rawlins S. L. , Ogata G.
Published: July 2010

This investigation was conducted to determine the integrated effects of concentration and duration of ozone exposure on the injury, growth, and mineral composition of pinto bean (Phaseolus vulgaris L.) during rapid vegetative growth and to evaluate the interactive effects of salinity.

Plants were grown in controlled environment chambers in non‐saline and two saline nutrients solution cultures having osmotic potentials of −0.4, −2.4, and −4.4 bars, respectively. Ozone‐free plants were compared with plants treated daily for 2 weeks with ozone doses of from 0.15 to 0.90 ppm‐hour.

Plant injury and reduction in growth were sigmoidal functions of ozone dose. Plant tolerance thresholds were found for both concentration and duration of ozone exposure. Daily exposures above threshold levels produced cumulative injury that progressed from the primary leaves to subsequent trifoliate leaves. Although salinity suppressed plant growth, it extended the tolerance threshold for duration of ozone exposure and significantly reduced the injury by ozone. Ozone decreased Ca, Mg, K, and N contents of the leaves, increased stem contents of these elements, and had relatively little effect on root contents. However, no serious nutritional imbalances were observed.
Termination of Late Season Cotton Fruiting with Growth Regulators as an Insect‐Control Technique
Authors: Kittock D. L. , Mauney Jack R. , Arle H. Fred , Bariola L. A.
Published: July 2010

A technique is proposed for reducing the number of overwintering pink bollworms [Pectinophora gossypiella (Saunders)] by reducing their food supply late in the year. This is done by using growth regulators that prevent formation of new cotton (Gossypium sp.) bolls late in the season, but do not affect development of existing bolls or vegetation. Since most of the late‐season bolls do not mature, the effect on lint yield would be minimal.

Three chemicals, (2‐chloroethyl) trimethyl ammonium chloride, (CCC); dimethylamine salt of (2,4‐dichlorophenoxy) acetic acid, (2,4‐D); and 2‐chloroethylphosphonic acid (Ethephon) were used. They were sprayed on cotton late in August and early in September. Each of the chemicals reduced the number of green bolls remaining after harvest by more than 90% at one or more dates in one or more tests. In most cases, lint yields were also reduced. In limited observations, we obtained 87 to 96% reduction in diapausing pink bollworm larvae from these treatments.

The effects of Ethephon on seed and fiber quality were too severe to warrant its further use. Residue of 2,4‐D in seeds reduced germination. CCC reduced fiber strength in two of four tests. Further testing of the last two chemicals and evaluation of other chemicals are warranted.
Effect of Feedlot Manure on Soil and Water Quality
Authors: Sommerfeldt Theron G. , Pittman U. J. , Milne R. A.
Published: July 2010

Research was conducted (i) to determine the contribution of representative feedlots in semiarid southern Alberta to soil and water pollution, and (ii) to determine the effect of long‐term applications of manure on the N, P, and soluble salt content of cultivated soil under irrigation.

The NO3‐N and available P content of the surface soil adjacent to the feedlots was generally greater than that of the soil away from the feedlots, but at depths greater than 150 cm the differences were usually small. Similarly, the concentration of NO3‐N and P in the ground water at 1‐ to 5‐m depths was usually increased only adjacent to the feedlot and, with minor exceptions, remained within “safe” limits most of the time. There was no evidence that a small lake or three permanent streams near feedlots were polluted by effluents from the feedlots.

Manure applied annually for 40 years at a rate of 70 metric tons/ha did not cause an undesirable buildup of N, P, or soluble salts in the soil.
Significance of pH and Chloride Concentration on Behavior of Heavy Metal Pollutants: Mercury(II), Cadmium(II), Zinc(II), and Lead(II)
Authors: Hahne H. C. H. , Kroontje W.
Published: July 2010

Calculations were performed (i) to assess the degree to which Hg(II), Cd(II), Zn(II), and Pb(II) complex with hydroxyl and chloride ions and (ii) to evaluate the significance of such complexation in natural systems. Results indicate that both the hydroxy and chloride complexes may contribute to the mobilization of these heavy metal ions in the environment.

Hydrolysis of Hg(II) becomes important at pH values above 1 whereas Pb(II), Zn(II), and Cd(ll) hydrolyze above pH 5, 7, and 8, respectively. Chlorides complex with Hg(II) at chloride concentrations above 10−9M (35 × 10−6 ppm). HgCl2 forms above 10−7.5M Cl−(1.1 × 10−3 ppm), and HgCl3− and HgCl42‐ formation occurs above 10−2M Cl−(350 ppm). The MCl+ species of Zn(II), Cd(II), and Pb(II) appear at chloride concentrations above 10−3M (35 ppm), and MCl2 complexes occur above 10−2M (350 ppm Cl−). The respective MCl3− and MCl42‐ species become important above 10−1M Cl−(3,500 ppm).

Hydrolysis and chloride complexation of these heavy metal ions are important factors affecting the solubility of the sparingly soluble salts of these metal ions. This is most pronounced for mercuric salts.

Intrinsic solubilities of the metal‐ion hydroxides allow for 160 ppm Zn(II) and 107 ppm Hg(II) to be soluble as complexed Zn(OH)2 and Hg(OH)2, respectively. These values are higher than calculated solubilities based on solubility products.

An example of the competition between hydroxy and chloride complexes shows that at pH 8.5 and a chloride concentration range of 350–60,000 ppm, Hg(II) and Cd(II) are mainly complexed by chlorides. Zn(II) and Pb(II), under these conditions, are predominantly in the form of hydroxy complexes.
Acetylcholinesterase Toxicity of Malathion and Its Metabolites
Authors: Walker W. W. , Stojanovic B. J.
Published: July 2010

Malathion, under in vitro laboratory conditions, is readily degraded by an Arthrobacter species to four metabolites—malathion half‐ester, malathion dicarboxylic acid, potassium dimethyl phosphorothioate, and potassium dimethyl phosphorodithioate. However, it is not clear whether or not this degradation represents a simultaneous detoxication of the malathion molecule. With this in mind, the relative toxicity of each of the four metabolites to bovine acetylcholinesterase was determined manometrically with the Warburg apparatus. Malathion half‐ester retained roughly one‐third the enzyme toxicity of unaltered malathion, while the other metabolites showed essentially no enzyme inhibition. It was concluded that while microbial conversion of malathion to malathion halfester may well represent complete malathion degradation, it does not constitute complete insecticide detoxication.
Screening for Phytotoxic Pesticide Interactions
Authors: Nash Ralph G. , Harris William G.
Published: July 2010

Of 165 combinations of pesticides screened on two plant species in the greenhouse, 13 combinations indicated a phytotoxic interaction on at least one plant species. Combinations of the herbicide 3‐(3,4‐dichlorophenyl)‐1,1‐dimethylurea (diuron) plus the insecticides O,O‐diethyl S‐[2‐(ethylthio)ethyl] phosphorodithioate (disulfoton) or 1‐naphthyl methylcarbamate (carbaryl) in soil were synergistically phytotoxic to oats (Avena sativa L.) and cucumbers (Cucumis sativus L.). A fungicide, p‐(dimethylamino) benzenediazo sodium sulfonate, was antagonistic to the herbicidal activity of all s‐triazine herbicides tested on cucumbers in greenhouse experiments, but not in the field or to other plant species. The fungicide apparently limited root uptake of the s‐triazine herbicides by limiting root growth. No chemical reaction was observed between the fungicide and the s‐triazine herbicides.
Using Poultry Litter, Irrigation, and Tall Fescue for No‐Till Corn Production
Authors: Carreker J. R. , Wilkinson S. R. , Box J. E. , Dawson R. N. , Beaty E. R. , Morris H. D. , Jones J. B.
Published: July 2010

A cropping system is needed in the Southern Piedmont and related areas for increasing production of grain and forage, controlling erosion, and providing a place for safe utilization of poultry litter. No‐till corn (Zea mays L.) production in tall fescue (Festuca arundinacea Schreb.) appears to offer such a system. Corn was notill planted and irrigated in live sod and in sod that was killed with 2.2 and 0.28 kg/ha atrazine and paraquat, respectively. Nitrogen, P, K, and lime applied uniformly to all treatments included 145, 98, 185, and 3,330 kg/ha in 1970 and 145, 138, 323, and 3,330 kg/ha in 1971, respectively. Subplot treatments were 5.6, 11.2, 22.4, and 44.8 metric tons/ha poultry litter, and 335 kg/ha N.

Measurements with electrical resistance blocks showed that soilwater content under the corn was never below 50% of the water between field capacity and wilting point. Corn population was higher and yields were better in the killed sod than in live sod both years. Yields in the killed sod were very satisfactory with 9,500 kg/ha (153 bu/acre) from 5.6 metric tons/ha poultry litter plus 145 kg/ha N and 12,960 kg/ha (207 bu/acre) from 480 kg/ha N. Tall fescue present in the live sod after corn harvest was above 2,000 kg/ha in 1970 and above 6,000 kg/ha in 1971. Dead grass plus poultry litter residues after killed sod in 1970 ranged from 6,360 kg/ha with N only to 30,200 kg/ha with 44.8 metric tons/ha poultry litter.

Poultry litter provides a vast resource of plant nutrients. No‐till corn in tall fescue with irrigation and poultry litter will produce needed grain, conserve soil and water, and turn a waste product into a resource.
Determining Phytotoxic Pesticide Interactions in Soil
Authors: Nash Ralph G. , Jansen Leonard L.
Published: July 2010

Methods of determining and describing total phytotoxic actions resulting from pesticides combined in soil have not always been appropriate. The best design appears to be a simple factorial. The criteria selected for analysis should be in a form suitable for statistical evaluation. Regression estimate analysis can identify, characterize, and express magnitude of a physiological interaction. An analysis of variance indicates only the presence of an interaction, Duncan's Multiple Range Test identifies an interaction, and Colby's method indicates magnitude of differences. The regression estimate analysis overcomes some of the statistical and interpretive limitations of the heretofore used Duncan's Multiple Range Test and Colby's method for phytotoxic interactions.
Interactive Effects of Salinity and Ozone on Growth and Yield of Garden Beet
Authors: Ogata Gen , Maas E. V.
Published: July 2010

The interactive effects of root media salinity and ambient ozone on injury, growth, and yield of garden beets (Beta vulgaris L.) were determined under controlled environmental conditions. Plants were grown in nonsaline and saline nutrient solution cultures having osmotic potentials of −0.4, −4.4, and −8.4 bars, respectively, and were exposed 5 weeks to 0.20 ppm ozone for 0 to 3 hours/day.

Growth of the nonsaline beet plants were not significantly affected by 0.20 ppm ozone until exposure times exceeded 1 hour/day, although foliar injury in the form of a reddish‐purple stipple had developed on mature leaves. Longer ozone exposures produced severe leaf necrosis and reduced the growth of tops and storage and fibrous roots as much as 50, 40, and 67%, respectively. In contrast, foliar ozone injury on plants grown in saline media developed more slowly and the growth of both tops and roots were relatively unaffected by ozone exposures of up to 3 hours/day. Some reduction in yield of storage roots did occur at −4.4 bars osmotic potential when plants were exposed to ozone for 3 hours/day. However, the beneficial effect of salinity in reducing ozone damage was offset by the suppressive effect of salinity on the yield of the storage root. Dry weights of the storage root were reduced nearly 25% at −4.4 bars osmotic potential.
Inhibition of Apparent Photosynthesis by Air Pollutants
Authors: Bennett Jesse H. , Hill A. Clyde
Published: July 2010

The reversible effects of hydrogen fluoride, sulfur dioxide, and chlorine exposures on net carbon dioxide absorption rates (apparent photosynthesis) of alfalfa (Medicago sativa L.) and barley (Hordeum vulgare L.) plants were studied. Pollutant exposures required (i) to reversibly depress CO2 uptake rates and (ii) to cause cellular necrosis in the leaves were appraised. Plant responses to these air pollutants were compared with responses observed from previous equivalent studies with ozone, nitric oxide, and nitrogen dioxide. The experimental data show that CO2 uptake could be reversibly suppressed by exposure dosages of these pollutants which did not cause cellular destruction in the leaves. However, except for the nitrogen oxides, some necrosis resulted from treatments which depressed CO2 uptake rates more than 25–60% (depending upon the pollutant) by the end of 2‐hour fumigation trials.

The six air pollutants can be ranked in the following order according to the relative amounts that plant CO2 uptake rates were depressed by the end of 2 hours of pollutant exposure: HF > 03 ≥ Cl2 > SO2 > NO2 > NO. Carbon monoxide was also tested but did not measurably reduce plant CO2 uptake when applied in concentrations ranging up to 80 ppm. The phytotoxicants ranked in essentially the reverse order when compared on the basis of the rapidity that CO2 uptake was suppressed as a function of exposure time. Nitric oxide treatments caused very rapid reductions in the plant CO2 uptake rates during the first hour of exposure. By this time, plant uptake rates had attained new (depressed) steady‐state equilibrium levels which were then maintained over the remainder of the expo,sure periods. Hydrogen fluoride treatment induced much more gradual reductions in plant CO2 uptake rates throughout the test periods. Plant responses to the other pollutants, SO2, NO2, Cl2, and O3, were intermediate between those caused by NO and HF.

The experimental plants were fumigated after steady‐state CO2 exchange rates were established and the percent reduction in the CO2 uptake (along with the rates of recovery) were determined. The investigations were conducted in two identical internalrecirculating environmental chambers (control and treatment chambers) designed to precisely control and continuously monitor light, temperature, wind parameters, relative humidity, and gas exchange rates.
The Effect of Flooding on Moth Fly Larvae and Zooglea in a Sewage Trickling Filter System
Authors: Callahan James T. , Bailey Richard L.
Published: July 2010

Populations of larval flies, particularly Psychoda alternata, are considered to be important to efficient BOD removal in sewage trickling filter systems. This importance arises from their grazing upon the zooglea which coats the filter substrate with the result that the zooglea is kept in a growth phase. Filter flooding is carried out to control the resident population of adult flies. It was hypothesized that the flooding routine also removes significant proportions of the larval fly population and the zooglea—effects which could be detrimental to the efficiency of a filter.

In order to assess the effects of filter flooding on the fly larvae and the zooglea, preflood and postflood samples were taken in such a filter in Athens, Georgia. On each of three dates before flooding and on the 3 days immediately after flooding, the filter was sampled for larvae and zooglea at 30.48 cm intervals to a total depth of 121.92 cm. Comparison of the preflood and postflood samples showed that both the larval fly population and the zooglea were significantly reduced by the flooding.

The data from the samples were extrapolated to the total volume of the filter bed. Losses from the filter attributable to flooding were estimated to be 1.6 × 108 individual larvae (more than 59% of the preflood total) and 660 kg of zooglea (approximately 47% of the preflood biomass).