bluuebunny/crossref_metadata_2025_split huggingface dataset:
Response of Northwest Douglas‐fir Stands to Urea: Correlations with Forest Soil Properties
Authors: Peterson C. E. , Ryan P. J. , Gessel S. P. 
Published: July 2010

AbstractReplicated forest floor and surface soil (0–15 cm) samples were obtained from control plots at 160 field installations in western Washington and Oregon. Six‐year growth responses of thinned and unthinned Douglas‐fir [Pseudotsuga menziesii (Mirb.) Franco] installations treated with 0, 224, and 448 kg of urea‐N ha−1 were correlated with 18 forest floor and surface soil properties of the control plots. Correlations for response with respective forest floor and soil data were produced for levels of fertilizer application and both basal area and volume response. Observed and estimated expressions of absolute and relative response were used in analyses. Forest floor nitrogen properties were the most highly correlated with various estimates of response in both thinned and unthinned stands; these correlations were generally independent of methods used to estimate response. For unthinned stands, C/N ratios of both forest floor and surface soil were well correlated with growth response to fertilizer, whereas for thinned stands, N content (kilograms per hectare) of the forest floor was consistently correlated with response.
Evidence Supporting Specific Adsorption of Boron on Synthetic Aluminum Hydroxides
Authors: Beyrouty C. A. , Van Scoyoc G. E. , Feldkamp J. R. 
Published: July 2010

AbstractAluminum hydroxide gels were precipitated in the presence of boron (B). Both chemical and infrared analyses were used to characterize the B adsorption sites on the Al(OH)3.The zero point of charge (ZPC) in a gel containing B was 1.6 to 2.1 pH units lower than a gel without B. This reduction was attributed to an increase in the negative charge of the hydroxide surface as a result of specific adsorption of B. Aging studies revealed that adsorbed B in gels retarded crystal growth of the Al(OH)3. The concentration of B in the total gel, in the electrical double layer and on the hydroxide surface was determined colorimetrically. Essentially all adsorbed boron was held onto the hydroxide surface.
Nitrogen‐15 Recovery for Five Years after Application of Ammonium Nitrate to Crested Wheatgrass
Authors: Power J. F. , Legg J. O. 
Published: July 2010

AbstractAlthough perennial grasses usually respond to N fertilization if there is adequate water, fertilizer N recovery is usually relatively low. This research was conducted to understand better the fate of fertilizer N applied to grasslands. Twenty open‐ended cylinders (102‐mm diam by 637‐mm length) were pressed into each of two main plots containing 4‐year‐old stands of crested wheatgrass [Agropyron desertorum (Fisch. ex Link) Schult.]. One plot had received no fertilizer N, and the other plot had received 22.4 g N/m2 each year since seeding. Enriched 15N was applied at the rate of 8.4 g N/m2 to a different replicated set of cylinders each of the 5 years of this study. Remaining cylinders received 8.4 g nonenriched N/m2 each year. Aboveground vegetation was harvested, and, after the fifth year, cylinders were removed from the soil. Roots were screened dry, and all plant material, roots, and soil were analyzed for total N and N‐isotope ratio.Average annual top growth varied fivefold as a result of highly variable precipitation and evaporation rate. Plant N concentration and uptake the first several seasons were about 25% greater from previously fertilized than from previously unfertilized soil. Cumulative recovery of 15N in tops increased with time, but considerable variation existed because of varied growing conditions between years. From 12 to 52% of the 15N applied was recovered in top growth in the season of application, representing about 75% of total isotope recovery in tops after four additional growing seasons. About 15% of the 15N was in roots after the first growing season, and about two‐thirds of this N appeared in plant tops within 3 y. Soil 15N varied from 29 to 49% of that applied, present mostly as organic N after the first season. About 70 to 95% of the 15N applied was accounted for in tops, roots, and soil, with little apparent relationship between 15N accounted for and either dry‐matter production or seasonal precipitation. Although uptake of soil N was initially 20 to 25% greater from previously fertilized than from unfertilized soil, this difference disappeared after the third year of fertilization, suggesting that at least 3 y of fertilization were required for the N cycle to readjust to a new steady state. Growing conditions the first few months after fertilizer application appear to have a major, but largely undefined, effect upon the fate of fertilizer N.
Oxygen Consumption and Denitrification Activity of a Conifer Forest Soil Profile
Authors: Pang Patrick Chi‐Kee , Cho Chai Moo 
Published: July 2010

AbstractForest soil profile samples (L‐H, 0–5, 5–15, 15–30, 30–60 cm depths) were collected from a Douglas‐fir [Pseudotsuga menziesii (Mirb.) Franco] plantation in British Columbia. These soil samples were incubated at 20°C in the presence of (15NH2)2CO, Ca(15NO3)2, and Na15NO2 to investigate the biological activity, expressed as oxygen consumption rate (O2CR), carbon dioxide production rate (CO2PR), and potential denitrification (both biological and chemical) activity under controlled conditions in the laboratory. The gaseous samples were analyzed mass spectrometrically. The O2CR of the L‐H sample was high (29.0 µg g−1 h−1) and decreased with depth in the mineral soil (2.9 µg g−1 h−1 at 30–60‐cm depth). The CO2PR followed the pattern of O2CR, indicating they are related. Denitrification depended on the N‐source. When Ca(15NO3)2 (100 mg N L−1) was applied to the L‐H samples, the NO‐3 was denitrified to N2O and N2 under anaerobic conditions. The quantity and percentage of applied‐N from Ca(15NO3)2 denitrified over the 168‐hour period decreased with increasing depth. When Na15NO2 (400 mg N L−1) was added to the L‐H samples, N2O and N2 were detected under aerobic conditions. The N2 production appeared to be the result of both chemical and biological denitrification. Denitrification was not detected when (15NH2)2CO (500 mg N L−1) was incubated with L‐H and 0 to 5‐cm soil profile samples under aerobic condition.
Electron Microprobe Analysis of Elements Associated with Zinc and Copper in an Oxidizing and an Anaerobic Soil Environment
Authors: Lee F. Y. , Kittrick J. A. 
Published: July 2010

AbstractA soil and a harbor sediment contaminated by heavy metals were examined with the electron microprobe to obtain direct evidence of elements associated with heavy metal phases in the samples. Approximately 12 × 103 particles were scanned in order to locate 30 that produced > 100 counts per second (cps) Zn or Cu X‐radiation. Sulfur was found to be significantly associated with Zn in the sediment (in ca. 83% of the particles). Most of the Cu‐containing particles in the soil (ca. 57%) were not associated with elements above atomic number 9. Sulfur (ca. 33%) and iron (ca. 27%), or both, were the most important associations with the remaining Cu‐containing particles. Zinc and copper appeared to be precipitated with the associated elements rather than being adsorbed on the particle surfaces. The results can be predicted from thermodynamic calculations combined with some reasonable assumptions. Compared to chemical extraction analysis, microprobe analysis is more accurate, but less precise for determining the chemical nature of Zn and Cu phases. It may be possible to similarly apply the microprobe to Zn and Cu phases in uncontaminated soils.
Spatial Variability of Nitrate in Irrigated Cotton: I. Petioles
Authors: Tabor J. A. , Warrick A. W. , Pennington D. A. , Myers D. E. 
Published: July 2010

AbstractGeostatistics, specifically the use of variograms and kriging, was used to determine the spatial variability of nitrates in cotton (Gossypium hirsutum L.) petioles. Petiole nitrates were shown to be spatially dependent in seven commercial fields. This spatial dependence can range from insignificant, where the inherent variability of sampling and analysis is relatively large, to strongly dependent. Data from a 360 by 360 m grid indicated an anisotropy of spatial dependence. Isotropic and anisotropic models for the grid‐sample field were compared using a “jack‐knifing” technique. The variograms and kriged maps of petiole nitrates suggest a strong influence due to cultural practices such as direction of rows and irrigation.
Soil Chemical Patterns under Eastern Oregon Plant Communities Dominated by Big Sagebrush
Authors: Doescher Paul S. , Miller Richard F. , Winward Alma H. 
Published: July 2010

AbstractThe objectives of this study were (i) to examine soil nutrient patterning in eastern Oregon plant communities dominated by subspecies of Artemisia tridentata Nutt., and (ii) to compare soil nutrient levels between adjacent sites characterized by contrasting amounts of sagebrush and perennial grasses. Horizontal and vertical soil chemical patterns were evident on all sites. Surface concentrations of nutrients were greates tunder shrubs in comparison to interspace and grass influenced soils. Values of total N, organic matter, K, and P tended to decrease with depth, while Mg concentrations generally increased in lower soil horizons. Soil pH was generally lower in upper soil horizons. Soil chemical differences between shrub, interspace and bunchgrass influenced soils became less distinct with increased soil depth. Differences in soil chemical levels between sites with a high proportion of perennial grasses to shrubs and sites with a low proportion of perennial grasses to shrubs were noted. However, no consistent patterns were evident.
Effects of Landslide Erosion on Subsequent Douglas‐fir Growth and Stocking Levels in the Western Cascades, Oregon
Authors: Miles D. W. R. , Swanson F. J. , Youngberg C. T. 
Published: July 2010

AbstractShallow, rapid landslides are common events in steep terrain of the Pacific Northwest. The effect of landslides on timber growth potential of forest land was estimated by examining a 30‐yr history of clearcutting and landsliding in the western Oregon Cascades. The height growth of Douglas‐fir [Pseudotsuga menziesii (Mirb.) Franco] and stocking level of all commercial conifer species on naturally regenerated landslides were compared with the height growth and stocking level on nearby, artificially regenerated clearcut units of similar aspect, elevation, ages, and slope position. Average height growth of Douglas‐fir trees 5 to 18 years old on the landslides was reduced 62% compared to trees on clearcuts, and the average stocking level was reduced 25% from the clearcut level. One‐third of the landslide area was estimated to be nonstockable because of unstable or impenetrable substrate.
A Rapid, Low‐Cost Method for Determination of Soil Bulk Density
Authors: Doran J. W. , Mielke L. N. 
Published: July 2010

AbstractProper characterization of soil bulk density is essential for an accurate interpretation of chemical and microbiological parameters in the field. Reluctance to report soil analyses on a volumetric basis is usually related to requirements of additional time and specialized equipment for determination of soil bulk density. We developed a rapid method utilizing a low‐cost hand sampler (< $125) for determination of soil bulk density over several intervals to a depth of 300 mm. The method appears accurate, using five cores per experimental unit, and enables collection of up to ten profiles in the same time required for taking one profile by the Uhland sampling techniques. The method is very precise and coefficients of variation over a range of tillage‐management practices, which include inherent soil variability, averaged below 5%. Soil samples collected with this method can also be used for other chemical and microbiological analyses.
The Influence of Plant Residues on Denitrification Rates in Conventional and Zero Tilled Soils
Authors: Aulakh M.S. , Rennie D. A. , Paul E. A. 
Published: July 2010

AbstractA field study was conducted with treatments consisting of a factorial combination of N (0 or 100 kg N ha−1 as (NH4)2SO4, straw (0 or 3000 kg ha−1), and two tillage treatments. Ground straw was mixed with the plow layer of soil in the conventional till (CT) plots and chopped straw was spread over the surface of the zero till (ZT) plots. Wheat (Triticum aestivum L.) was grown as the test crop. Gaseous losses of N were measured using the acetylene inhibition‐soil core technique and compared with loss estimates obtained from the imbalance in the N budget of 15N‐treated microplots located within the larger yield plots. When adequate inorganic N was present, the incorporation of straw in CT soil or the application of straw on the surface of ZT soil approximately doubled the accumulative gaseous N losses. The straw apparently increased the supply of energy material available to denitrifying organisms, and also increased surface soil moisture content (particularly during the month of June). This further stimulated denitrification in ZT soil. Unaccounted 15N on the fertilizer N balance studies agreed closely with cumulative N losses using the acetylene inhibition technique.
Soil and Water Losses as Affected by Tillage and Manure Application
Authors: Mueller D. H. , Wendt R. C. , Daniel T. C. 
Published: July 2010

AbstractLittle data are available on conservation tillage under field conditions characteristic of a dairy operation. Thus, simulated rainfall was used to compare soil and water losses among conventional, chisel, and no‐till systems for corn both with and without surface‐applied manure prior to tillage. Rainfall was applied at several times during the growing season of 1978 and 1979. A portion of the previous year's crop residue was removed in 1978 and all the residue was left in 1979. A tillage × date interaction was observed for runoff losses in both years of the experiment. Significantly lower runoff occurred for the conventional and chisel systems relative to the no‐till system immediately after planting. At later sampling periods, runoff significantly increased for the conventional system and runoff losses approached that from no‐till. In contrast, lower runoff losses occurred for the chisel system relative to the other tillage systems. This was most apparent in 1979 when more residue was partially incorporated or left on the soil surface. Surface spread manure decreased runoff for all tillage treatments at the September 1978 sampling period and at both sampling periods in 1979. The results indicated the greatest response with the chisel system. In 1978 and 1979, a tillage × manure interaction was observed for soil loss. In 1978, little difference in soil loss was observed among unmanured tillage treatments. However, the application of manure reduced soil losses for chisel and no‐till systems relative to the conventional system. In 1979, soil losses were lower from unmanured chisel and unmanured no‐till treatments than from the unmanured conventional treatment. Soil losses were significantly lower from the manured chisel treatment than all other treatments.
Using Foliar Analysis to Classify Nitrogen‐Deficient Sites
Authors: Comerford N. B. , Fisher R. F. 
Published: July 2010

AbstractDiscriminant analysis was used to evaluate the efficacy of using foliage N concentration (FN), an adjustment of the foliage N concentration based on stand age (FA), and a nitrogen/phosphorus ratio (N/P) to classify N‐deficient sites. N/P was the superior index of N deficiency. FA was consistently a more reliable classification technique than FN, but it was not accurate enough for operational use. An N/P ratio of 14 to 15 proved to be the critical ratio. Foliage nutrient analysis was not a useful technique for classifying sites for their long‐term response to N fertilization. This is due primarily to the fact that volume response to N fertilization is a function of site and stand conditions after fertilization as well as prior stand N status.
Effect of Study Duration on Measurements of Water Table Depths
Authors: Zobeck T. M. , Ritchie A. 
Published: July 2010

AbstractWater table depths and precipitation were measured over a 10‐yr period on four fine‐textured soils in central Ohio. Well, moderately well, poorly and very poorly drained soils were observed to compare the effect of study duration on water table depth measurements. Relatively long‐term (10‐yr) average water table levels were compared to shorter‐term 5‐, 4‐, 3‐, 2‐ and 1‐yr studies. Average water table depth measurements of the shorter‐term studies had greater deviations from the long‐term average as soil wetness increased, and study duration decreased during February, March, and May. Three‐year studies are suggested for similar soils to adequately predict water table depth assuming moderate deviations (up to 50 cm) from the long‐term average depth during February, March and May in unusually wet or dry years.
Evaluation of Some New Tracers for Soil Water Studies
Authors: Bowman R. S. 
Published: July 2010

AbstractSix anions which showed potential as tracers of soil water movement were evaluated in laboratory and field experiments. The anions included iodide (I‐), thiocyanate (SCN‐), and four fluorobenzoates: m‐(trifluoromethyl)benzoic acid (m‐TFMBA), o‐(trifluoromethyl)benzoic acid (o‐TFMBA), pentafluorobenzoic acid (PFBA) and 2,6‐difluorobenzoic acid (2,6‐DFBA). The sorption and mobility characteristics of the six potential tracers were compared to those of bromide (Br‐), which served as an index tracer in all experiments. Initial tracer concentrations ranged from 20 to 100 mg L−1. The anions were quantified simultaneously in sub‐mL samples of soil solution using a high performance liquid chromatography technique. Batch equilibrations (28 d), and breakthrough curves (7 to 10 d) in a 2.5‐m column of loamy sand, under both ponded and trickle‐irrigated conditions, indicated that all the tracers except SCN‐ were conservative and were not sorbed. SCN‐ was not retarded in the column studies but did show a negative mass balance, most likely due to chemical and/or biological transformation. Distribution of a tracer solution applied to a field soil was monitored for 69 d in soil water from suction samplers (1.0‐ and 1.8‐m depth) and in extracts from core samples. SCN‐, I‐, and m‐TFMBA showed reduced concentrations relative to Br‐ at all sampling times and depths; o‐TFMBA, PFBA, and 2,6‐DFBA had distributions similar to that of Br‐. These latter three fluorobenzoates show promise as laboratory and field tracers of soil water, particularly where multiple tracing tests or totally exotic tracers are required.
Sodium‐Calcium‐Magnesium Exchange Reactions on a Montmorillonitic Soil: I. Binary Exchange Reactions
Authors: Fletcher Philip , Sposito Garrison , LeVesque C. S. 
Published: July 2010

AbstractThe binary cation exchange processes, Na → Ca, Na → Mg, and Ca → Mg, were investigated at 298 K for a montmorillonitic soil separate (principally clay and silt) suspended in a 50 mol m−3 perchlorate background at pH 6, 6.6, or 7. The resulting exchange isotherms indicated some preference on the soil for Ca and Mg over Na, and for Ca over Mg. These preferences were attributed primarily to organic matter associated with the soil separate, since previous studies had shown that pure montmorillonite exhibits essentially no preference among the three cations under the same conditions as in the present experiments. The exchange isotherms at pH 6, 6.6, and 7 were congruent for all three binary exchange reactions, showing that, at these pH values, proton competition did not affect the exchange selectivity of the soil. The total adsorbed metal charge, Q0, however, increased with the pH value, as expected from the presence of organic matter in the soil, and varied with the surface composition of the exchanger. This variation was rationalized as a net effect of the ionic potential and Lewis acid softness properties of the exchangeable metal cations. Greater ionic potential was considered to result in greater proton displacing power, whereas greater Lewis acid softness was considered to result in stronger complex formation between a metal cation and organic functional groups. Thus, increasing ionic potential could produce an increase in Q0, but increasing Lewis acid softness could produce a decrease in exchangeability and consequent decrease in Q0. Ionic potential was the dominant consideration in Na → Mg exchange, whereas Lewis acid softness played the principal role in Na → Ca and Mg → Ca exchange.
Fallow Tillage Influence on Spring Populations of Soil Nitrifiers, Denitrifiers, and Available Nitrogen
Authors: Broder M. W. , Doran J. W. , Peterson G. A. , Fenster C. R. 
Published: July 2010

AbstractThe influence of plow, subtillage, and no‐tillage fallow management on nitrifier and denitrifier populations and available N in surface soil (300 mm) was evaluated at two sites in western Nebraska during spring growth of winter wheat (Triticum aestivum L.). Previous management differed considerably and tillage comparisons at one site were established 11 years earlier in land previously cultivated and at the other 9 years earlier in native sod. At both sites, nitrifier populations in the surface 150 mm of no‐tillage and subtillage soils were 22 to 56% and 16 to 35% lower, respectively, than those in plowed soil. Soil denitrifier populations tended to increase with less tillage. Differences in soil water content and temperature were major factors influencing differences in microbial populations between tillage practices. Higher water content in reduced tillage soils during early spring paralleled lower nitrifier and higher denitrifier populations as compared with plowed soils. These differences apparently resulted from greater aeration in plowed soils. Soil temperatures during the spring were well below optimum for mineralization and nitrification, particularly on subtillage and no‐tillage soils which averaged 1 and 2°C cooler, respectively, than plowed soils. Surface applications of 44 kg N/ha as NH4NO3 increased soil nitrifier populations six to nine fold in the surface 0‐ to 150‐mm layer; this effect was not influenced by tillage practice. Lower populations of nitrifiers and higher populations of denitrifiers were paralleled by lower NO‐3‐N levels in no‐tilled compared with plowed soils. Levels of potentially mineralizable N (PMN) in the surface 0‐ to 150‐mm layer of no‐tillage and subtillage soils at the previously cultivated site averaged 20 and 12% higher, respectively, than plowed soils. At the native sod site, differences in soil PMN between tillage practices were minimal. Changes in the soil environment and availability of N as a result of tillage can be modified by previous management history.
Nitrogen Transformations under Zero and Shallow Tillage
Authors: Carter M. R. , Rennie D. A. 
Published: July 2010

AbstractA field study was conducted with the objective of determining if differences occur in soil N transformations between zero and conventional tillage systems. Tillage comparisons of 2, 4, 12, and 16 yr duration were studied at four locations on Chernozemic soils in Western Canada. Determination of mineral N levels and immobilization of 15N‐urea fertilizer indicated that only slight, periodic, transient differences occurred between tillage systems. The degree of N mineralization‐immobilization turnover, which was associated with the incorporation of crop residues and level of labile organic matter in the surface soil, was not markedly affected by tillage differences. Over the growing season, fertilizer N entering the nonmicrobial biomass organic N pool increased relative to the microbial biomass pool, suggesting that in both systems N was entering more stabilized forms of organic N over time. These results would suggest that the differences in tillage system did not cause marked changes in the soil N cycle.