bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Impact of Nitrification on Soil Acidification and Cation Leaching in a Red Alder Ecosystem
Authors: Van Miegroet H. , Cole D. W. 
Published: July 2010

AbstractThe objectives of this study were to investigate the impacts of internal nitrification on soil and soil solution acidity and on the rate of nutrient export through NO3− mediated leaching. This was achieved by comparing soil chemical properties and soil solution composition within a naturally N‐rich red alder (Alnus rubra Bong.) ecosystem to those of an adjacent Douglas‐fir [Pseudotsuga menziesil (Mirbel) Franco] forest where soil N levels were significantly lower and no measurable HNO3 production could be observed. In the red alder system, where > 100 kg ha−1 yr−1 of N were added through symbiotic N2 fixation, the net annual NO3− leaching past the 40‐cm soil depth amounted to 3460 mol charges ha−1, and NO3− concentrations in the solutions collected below 40 cm periodically exceeded drinking water standards of 10 mg L−1. The H+ and NO3− release was most pronounced in the forest floor and top 10 cm of the soil under alder occupancy and caused significant acidification of percolating solutions. Less than 1% of the total H+ input from internal (nitrification) and external (atmospheric) sources leached below the 40‐cm depth, which was indicative for the strong buffering capacity of this particular soil. The cation displacement reactions involved in this pH buffering caused a 15% decline in base saturation and a significant acidification of the upper part of the soil profile. The presence of large amounts of mobile NO3− in solution triggered accelerated cation leaching, causing a selective redistribution of primarily exchangeable Ca2+ from the A to the B horizon. These field studies lead us to conclude that the rate and the selectivity of NO3− mediated leaching in a red alder system could significantly lower the exchangeable cation pool in the rooting zone or cause nutrient imbalance, if a site is managed for repeated rotations of red alder.
Availability of Nitrogen in Municipal, Industrial, and Animal Wastes
Authors: King Larry D. 
Published: July 2010

AbstractNitrogen availability in soil amendments is important from both a crop production and an environmental protection standpoint. Municipal, industrial, and animal wastes were incubated with soil for 16 weeks and then NH4+‐N + NO3−‐N determined. Some of the wastes with high C/N ratios received supplemental inorganic N prior to incubation. Available N was generally greater from aerobically digested municipal sewage sludges than from anaerobically digested ones. However, variation within each sludge type was large and using an average value could lead to large errors in application rates. Availability of N in industrial wastes ranged from immobilization with paper mill sludges to 520 g kg−1 of the organic N in sludge from a poultry processing plant. A regression model, significant at the 0.001% level, predicted availability of N in aerobic and anaerobic municipal sludges within ± 30% of actual values [(g available N)/(kg organic N) = 380 + 135 (g organic N)/(kg waste) − 128(g total N)/(kg waste) + 1020(g C/g organic N) − 1120(g C/g total N), R2 = 0.89]. The model was not effective with data from other studies with different soils and sludges. The quantity of supplemental inorganic N immobilized by wastes having high C/N ratios increased with inorganic N added.
Effects of Saline‐Sodic Soil Chemistry on Soybean Mineral Composition and Stomatal Resistance
Authors: Coale F. J. , Evangelou V. P. , Grove J. H. 
Published: July 2010

AbstractSoybean [Glycine max (L.) Merr.] productivity is severely limited by saline‐sodic soil conditions that occur in isolated spots in the river bottoms of western Kentucky. Productivity of soybeans grown on a gradient of soils of increasing saline‐sodic character were studied in greenhouse experiments. Soils with electrical conductivity (EC) exceeding 3.20 dS m−1 would not support soybean growth. Soybean plants accumulated significant quantities of Na when soil solution sodium adsorption ratio (SAR) exceeded 6.4 and relative tissue Na accumulation was highly correlated with SAR. Estimates of potential productivity were made by stomatal diffusive resistance measurements at three vegetative growth stages. Potential productivity was severely limited under conditions of high soil salinity. In soils of lower EC (< ≈ 2 dS m−1), soybean performance was affected to a greater extent by changes in SAR than by changes in EC. Dry matter production decreased with increasing SAR under low EC soil conditions.In a second experiment, saline‐sodic soil was amended with four rates of gypsum (CaSO4·2H2O), (0, 2.6, 6.0, and 12.9 g kg−1). Gypsum‐amended pots were leached until EC was < 3.0 dS m−1. Plant dry matter production was minimized with the 2.6 g kg−1 amendment, which also produced plants with significantly reduced and negligible Na contents. At early growth stages (V4 and V7), stomatal diffusive resistance of plants grown on the gypsum‐amended soils was not affected by increasing SAR. Diffusive resistance measurements of large vegetative plants (V10) increased significantly at low soil solution SAR. The addition of gypsum apparently reduced the detrimental effects of physical impedence to root development and function in the poorly structured soil as well as soil solution SAR. The improved physical structure of the gypsum‐amended soil could improve root development, function, and crop productivity.
Methane Emissions to the Atmosphere Through Aquatic Plants
Authors: Sebacher Daniel I. , Harriss Robert C. , Bartlett Karen B. 
Published: July 2010

AbstractThe movement of methane (CH4) from anaerobic sediments through the leaves, stems, and flowers of aquatic plants and into the atmosphere was found to provide a significant pathway for the emission of CH4 from the aquatic substrates of flooded wetlands. Methane concentrations well above the surrounding ambient air levels were found in the mesophyll of 16 varieties of aquatic plants and are attributed to transpiration, diffusion, and pressure‐induced flow of gaseous CH4 from the roots when they are embedded in CH4‐saturated anaerobic sediments. Methane emissions from the emergent parts of aquatic plants were measured using floating chamber techniques and by enclosing the plants in polyethylene bags of known volume. Concentration changes were monitored in the trapped air using syringes and gas chromatographic techniques. Vertical profiles of dissolved CH4 in sediment pore water surrounding the aquatic plants' rhizomes were obtained using an interstitial sampling technique. Methane emissions from the aquatic plants studied varied from 14.8 mg CH4 d−1 to levels too low to be detectable. Rooted and unrooted freshwater aquatic plants were studied as well as saltwater and brackish water plants. Included in the experiment is a detailed set of measurements on CH4 emissions from the common cattail (Typha latifolia). This paper illustrates that aquatic plants play an important gas exchange role in the C cycle between wetlands and the atmosphere.
Cotton Yield Responses to Ozone as Mediated by Soil Moisture and Evapotranspiration
Authors: Temple Patrick J. , Taylor O. Clifton , Benoit Lawrence F. 
Published: July 2010

AbstractA 2‐yr field study was conducted to determine injury and yield responses of normally irrigated and water‐stressed cotton (Gossypium hirsutum L.) to a gradient of ozone (O3) concentrations. Cotton (cv. SJ‐2), grown in open‐top chambers in the Central Valley of California, was exposed to six O3 treatments ranging from charcoal‐filtered (CF) to ambient plus 0.10 µL L−1 O3 (1981) or twice ambient O3 concentrations (1982) for the growing seasons of 1981 and 1982. Half the plots were irrigated optimally and the other half were provided with 25% (1981) or 20% (1982) less irrigation water (water‐stressed treatment). During the typically hot, dry growing season of 1981, cotton yield in normally irrigated treatments was reduced 20% by ambient levels of O3 in nonfiltered chambers (NF) relative to CF controls. Doubling ambient O3 concentration reduced yield 45%. Water‐stressed plants showed almost no response to O3. In 1982, the weather was cooler and cloudier than normal and potential evapotranspiration during the growing season averaged 20% less and ambient O3 concentrations averaged 39% lower than in 1981. Under these conditions, cotton yields at both levels of soil moisture treatments responded similarly to O3. Yields in NF chambers were reduced 15% relative to CF chambers. Doubling ambient O3 concentrations reduced yields 65%. The greater relative response of cotton to O3 in 1982 may have resulted from the cooler, more humid growing conditions, which increased the susceptibility of cotton to O3.
Effect of Acid Precipitation on Soil Microbial Activity: I. Soil Core Studies
Authors: Bitton Gabriel , Boylan Rae Ann 
Published: July 2010

AbstractA study using soil columns was undertaken to examine the effect of acid precipitation on selected microbial processes. Following short‐term (92 d) exposure of soil cores to acid rain at pH 3.7 and 3.0, no alteration in enzyme activities was observed. The effect on soil respiration was dependent on soil type. Dinitrogen fixation was reduced only in one of the soils by the rain of pH 3.0. Following long‐term (690 d) exposure to acid rain, alterations in enzyme activities and CO2 evolution were dependent on the soil type. No reduction in adenosine triphosphate (ATP) content or N2 fixation were observed.
Stream‐Watershed Relations in the Missouri Ozark Plateau Province
Authors: Smart Miles M. , Jones John R. , Sebaugh Jeanne L. 
Published: July 2010

AbstractWater chemistry and algal chlorophyll values in Missouri Ozark streams were more strongly related to land‐use practices on the watershed than bedrock geology or soil association. In general, concentrations of nutrients, chlorophyll, and most major ions were lowest in streams draining forests, intermediate in streams draining pastures, and highest in streams draining urban areas. In streams draining both forest and pasture areas, there was an exponential increase in the concentration of total P, total N, NO3−‐N, Na+, Cl−, and suspended chlorophyll a with an increase in percent pasture area on the watershed. These relations help identify the relative importance of land use on water chemistry and algal chlorophyll values, explain differences among streams in the region and enable us to approximate the impact of forest‐pasture conversion on streams not yet affected.
Residual Phytotoxicity of Chlorsulfuron in Two Soils
Authors: Anderson R. L. , Barrett M. R. 
Published: July 2010

AbstractChlorsulfuron {2‐chloro‐N‐[(4‐methoxy‐6‐methyl‐1,3,5‐triazin‐2‐yl) amino carbonyl] benzenesulfonamide} selectively controls broad‐leaf weeds in winter wheat (Triticum aestivum L.), but also is extremely persistent in soil, resulting in residual injury to succeeding crops that are susceptible to chlorsulfuron. To determine the factors affecting chlorsulfuron degradation, the effect of environmental variables and method of application on chlorsulfuron persistence was measured in a loam and sandy loam soil using a corn (Zea mays L.) root bioassay. Increasing soil temperature from 20 to 40°C decreased chlorsulfuron persistence, with significant differences in chlorsulfuron concentration occurring 31 d after application to the sandy loam soil. Soil water level affected chlorsulfuron persistence only in the loam soil, where increasing the soil water level decreased persistence. Adding wheat residue to the soils increased chlorsulfuron persistence in the sandy loam, but not in the loam soil. One possible explanation for this reduced degradation in the sandy loam was a shift in pH toward basicity, as the addition of 0.050 kg kg−1 wheat residue raised the pH from 6.1 to 7.2. In the loam soil, the wheat residue did not affect soil I~H. Chlorsulfuron persistence was affected by texture, with longer activity occurring in the loam soil in all studies. Incorporating chlorsulfuron caused a greater loss of chlorsulfuron activity in the sandy loam, indicating that incorporation may influence chlorsulfuron persistence.
Adsorption‐Desorption Kinetics of Atrazine and Linuron in Freshwater‐Sediment Aqueous Slurries
Authors: Wauchope R. D. , Myers R. S. 
Published: July 2010

AbstractA fast sampling and filtration technique was used to determine the rapidity with which the herbicides atrazine (2‐chloro‐4‐[ethylamino]‐6‐[isopropylamino]‐s‐triazine) and linuron (3‐[3,4‐dichlorophenyl]‐1‐methoxy‐1‐methylurea) are adsorbed or desorbed in sediment‐water mixtures. When aqueous solutions of the herbicides were exposed to wet sediment, or when wet sediments containing the adsorbed herbicides were exposed to water, the resulting adsorption or desorption, respectively, was initially very fast, approaching 75% of equilibrium values within 3 to 6 min. Herbicide adsorption on the sediments was completely reversible after 2 h of adsorption time: kinetic parameters obtained from a statistical fit of a sequential‐equilibria model to the adsorption data also fit desorption data. These results indicate that for these herbicides and similar nonionic solutes that have been in contact with sediment surfaces for ≤ 2 h, nonpoint pollution models for mixing streams may, to a first approximation, assume that adsorption‐desorption reequilibration is reversible and established rapidly relative to stream movement and sedimentation times.
Simulation Model for Soil Erosion‐Productivity Relationships
Authors: Shaffer Marvin J. 
Published: July 2010

AbstractA mathematical model is described that simulates the impact of soil erosion on the short and long‐term productivity of soil. The model is known as the Nitrogen‐Tillage‐Residue Management (NTRM) model and has capabilities at the research level to simulate complex interactions of a growing crop such as corn (Zea mays L.) with climate inputs together with physical, chemical, and biological properties of the soil. Nitrogen‐Tillage‐Residue Management is intended to provide a means of evaluating existing and proposed soil management practices in the subject areas of erosion, soil fertility, tillage, crop residues, and irrigation. Illustration of model output, validation, and application is provided for three soils in the northern Corn Belt. These include a Fayette silt loam (Typic Hapludalf) (deep loess), a Dubuque silt loam (Typic Hapludalf) (shallow to bedrock), and a Dakota fine sandy loam (Typic Argiudoll) (shallow to coarse material). Corn growth and yield are simulated under noneroded and two levels of eroded conditions for a period of 100 yr. Management techniques, which include supplemental N, conservation tillage, and irrigation, are simulated on the eroded profiles to evaluate relative benefits and demonstrate the types of results produced by model sensitivity analyses.
Water Quality from Erosion Control Structures in Nebraska
Authors: Schepers J. S. , Francis D. D. , Mielke L. N. 
Published: July 2010

AbstractRunoff collected from terrace and sediment‐control basins having tile‐outlet systems was compared with runoff water quality from Maple Creek in northeastern Nebraska. This study was part of a Model Implementation Project (MIP) initiated in 1978 to accelerate land treatment for erosion control and development of best management practices (BMPs). Soils in the area are very erosive (Nora‐Crofton complex) when subjected to high‐intensity rainfall in the spring and summer. Sediment concentrations in runoff from the terraces and sediment basins were initially high and comparable to stream concentrations until a pool of runoff water formed around the riser inlet of the tile discharge system. Formation of a pool allowed sediment to settle out away from the riser inlet, thus reducing sediment losses from the field. Sediment‐borne N and P accounted for 85 to 98% of total N and P losses from the land. Because tile‐outlet terraces and sediment basins effectively reduced sediment and nutrient concentrations in runoff, they proved to be an effective BMP for use by producers.
Aflatoxin Contamination of Preharvest Corn in Georgia: A Six‐Year Study of Insect Damage and Visible Aspergillus flavus
Authors: Mc Millian W. W. , Wilson D. M. , Widstrom N. W. 
Published: July 2010

AbstractInsect damage, Aspergillus flavus Link infection, and aflatoxin contamination are recurring problems in preharvest corn (Zea mays L.) in the Coastal Plain of Georgia. A 6‐yr study (1977–1982) over 46‐county area revealed that insect damage ranged from a mean of 1.7 cm per ear in 1979 to 4.0 cm per ear in 1977. The incidence of aflatoxin contamination in grain samples ranged from 57% in 1982 to 100% in 1980. The highest concentration of aflatoxin (4708 µg kg−1 was recorded in a feld sample collected in 1977. The action level set by the Food and Drug Administration for aflatoxin is 20 µg kg−1. Insect damage contributed significantly to enhanced A. flavus sporulation and aflatoxin contamination. Levels of aflatoxin were positively correlated with temperature and total net evaporation. The occurrence of undamaged, uncontaminated corn in the Coastal Plain during a majority of the years suggests that crop management, including hybrid selection, planting date, and irrigation, may have a significant influence on the quantity of quality corn grain produced.
Fate of 2,4‐D Iso‐octyl Ester after Application to a Wheat Field
Authors: Grover R. , Shewchuk S. R. , Cessna A. J. , Smith A. E. , Hunter J. H. 
Published: July 2010

AbstractDissipation of iso‐octyl ester of 2,4‐dichlorophenoxyacetic acid (2,4‐D) and its acid metabolite in air, crop, and soil components were measured in a wheat (Triticum aestivum L.) field during and following application. Drift losses during application were only 0.2% of the amount applied. Air samples, collected at six heights ranging from 30 to 200 cm above the crop canopy during the first 7 d after application showed distinct ester gradients in the air, with concentration highest in the samples closest to the crop canopy. The highest concentration was measured during the afternoon of day 1 when 1604 ng m−3 were recorded 30 cm above the crop canopy. The vertical flux of the ester showed distinct diurnal variations with maxima reached in the early afternoon of day 1 and 2, followed by a rapid decline of the ester flux thereafter, corresponding with the depletion of the ester from the crop canopy. The total or cumulative vapor losses of the iso‐octyl ester over the 5‐d sampling period were estimated to be 93.5 g ha−1 or 20.8% of the amount applied.The crop canopy intercepted 52% of the applied ester and acted as the major source of vapor losses. The magnitude of vapor activity was controlled primarily by the atmospheric stability and air temperature following application. On entry into the crop, the ester was hydrolyzed to the acid metabolite, which reached its maximum level on day 3. There appeared to be a rapid initial metabolism of the acid followed by a slow decline.Ester losses from the soil surface occurred only when the soil surface was moist, i.e., after a rainfall event or in the early hours of the morning following the deposition of dew. In addition, both the hydrolysis of the ester and the subsequent degradation of its acid metabolite in the soil were dependent on the availability of surface soil moisture. No detectable 2,4‐D remained in the soil after 34 d.
Mobility and Persistence of Hexazinone in a Forest Watershed
Authors: Bouchard D. C. , Lavy T. L. , Lawson E. R. 
Published: July 2010

AbstractThe concentration of hexazinone [3‐cyclohexyl‐6‐(dimethylamino)‐1‐methyl‐1,3,5‐triazine‐2,4(1H,3H)‐dione] in soil, water, and plant tissue was monitored following hexazinone application (2.0 kg a.i./ha) to an 11.5‐ha watershed in northwestern Arkansas. The hexazinone concentration in the top 10 cm of soil on the watershed decreased to approximately 10% of the initial concentration in 42 d. Hexazinone dissipation rate on the watershed was more rapid than could be accounted for solely by degradation. Leaching of hexazinone to lower soil depths probably was important to hexazinone dissipation. Hexazinone degradation in soil incubated at 10 and 30°C followed first‐order kinetics and had a half‐life of 77 d at 30°C. Hexazinone was stable in incubated stream water requiring several years for 50% disappearance of the compound at 30°C. The maximum hexazinone concentration in the stream that drained the watershed was 14 µg/L, and hexazinone residues (< 3 µg/L) were detected in stream discharge over 1 yr after application. The amount of hexazinone transported from the watershed in stream discharge represented 2.0 to 3.0% of the amount of initially applied. Analyses of oak foliage and leaf litter collected from the forest floor indicated that < 0.10% of the hexazinone applied was returned to the forest floor in leaf deposition.
Nitrogen Fertilization and Ground Cover in a Hybrid Poplar Plantation: Effects on Nitrate Leaching
Authors: Mc Laughlin Richard A. , Pope Phillip E. , Hansen Edward A. 
Published: July 2010

AbstractA 3‐yr study in northern Wisconsin measured the effects of ground cover treatments and N fertilization on tree growth, NO3−‐N leaching, and N mineralization in an irrigated hybrid poplar (Populus deltoides Bartr. × P. trichocarpa Torr. and Gray, clone NC‐9922) plantation. Annually fertilized (112 kg N/ha per year) and unfertilized plots were either maintained weed‐free (bare soil), allowed to revegetate with native weeds, or seeded to birdsfoot trefoil (Lotus corniculatus L.). Soil solution NO3−‐N was monitored in samples from permanently installed cup lysimeters. During the first two growing seasons, fertilization in bare soil plots increased NO3−‐N concentrations below the rooting zone to over 150 mg N/L. Tree growth response to fertilization in these plots occurred primarily in the third growing season, and NO3−‐N concentrations were much lower in and below the rooting zone relative to previous years. Fertilization increased NO3−‐N concentrations in the rooting zone during growing seasons two through four in trefoil plots and three and four in native weed plots. Nitrate‐N concentrations below the rooting zone in all trefoil and native weed plots averaged ≤ 11 mg/L until the end of the fourth growing season when it averaged 20 to 24 mg/L in fertilized plots. Fertilization significantly increased soil N mineralization in buried plastic bags only in plots with a ground cover and was 42 to 47% greater in these plots compared with fertilized bare soil plots. This study indicates that ground cover plays an important role in preventing leaching losses of fertilizer and native soil N in young biomass plantations.