bluuebunny/crossref_metadata_2025 huggingface dataset:
Soil Test Calibration for Establishment of Turfgrass Monostands
Authors: Turner T. R. , Waddington D. V.
Published: July 2010

Little information is currently available relating fertilization and soil fertility to turfgrass establishment response. A field study was conducted on Hagerstown soil (fine, mixed, mesic, Typic Hapludalf) to determine the effects of seedbed applications of P, K, and limestone on establishment rate and quality of monostands of ‘Baron’ Kentucky bluegrass (Poa pratensis L.), ‘Atlanta’ Chewings fescue (Festuca rubra var. commutata Gaud.), and ‘Pennfine’ perennial ryegrass (Lolium perenne L.) Phosphorus applications ranged from 0 to 8.0 kg/are (1 are = 100 m2), potassium from 0 to 15.2 kg/are, and limestone from zero to 122.0 kg/are. Initial soil test levels were pH 5.7; 60 kg/ha of P; and 0.18, 0.7, and 4.3 cmo (p+)/kg of K, Mg, and Ca, respectively. Phosphorus additions to this soil had the most important effect on turfgrass establishment. The initial soil level of 60 kg/ha not sufficient for rapid turfgrass establishment. Seedbed P applications in the range of 1.6 to 4.0 kg P/are, resulting in soil P levels of approximately 110 to 180 kg/ha, proved to be most satisfactory in promoting rapid establishment as determined by turfgrass chemical composition, ground cover, clipping yield, and quality. Differences due to P tended to diminish with time, indicating that where rapid establishment is not critical, 60 kg/ha of P in this soil may be sufficient to obtain satisfactory stands of the species investigated. The initial pH, K, and Ca levels were sufficient for satisfactory turfgrass establishment on this soil. Limestone applications did not affect ground cover, tended to reduce initial clipping yields, had little influence on turfgrass quality, slightly reduced sod strength, and generally did not greatly affect tissue Ca levels. Potassium applications either reduced or had no effect on initial ground cover and had little effect on turfgrass quality. Although tissue K was substantially increased by K applications, tissue K levels of all three species on plots not fertilized with K were still much higher than levels generally considered critical or deficient.
Soil Genesis in a Natrargid‐Haplargid Complex in Northern Montana
Authors: Munn L. C. , Boehm M. M.
Published: July 2010

Classical theory of the genesis of Natargids (solonetz) involves the upward movement of sodium from a water table. Examination of 24 pedons representing four Soil Series developed in glacial till on the Northern Great Plains (Montana) suggests that Natrargids (solonetz and solodized‐solonetz) and Haplargids (soloth) can develop in the absence of a water table. The four soils occur as a complex on “panspot” rangeland with the soloth and solodized‐solonetz on microknolls and the solonetz in microdepressions. The panspot soils have significantly (p = 0.01) greater B horizon clay contents than associated non‐panspot soils. X‐ray diffraction analyses indicate decomposition of smectite inherited from the parent material in the sola of all soils. Solonization of the panspots is driven by reduced infiltration and subsurface water movement in response to matric and osmotic potential gradients. Panspots occur over high points in the till‐shale boundary where the wetting front penetrates into the salty, calcareous till. Movement of sodium upwards from the shale contact results in dispersion of the panspot B horizon. Natric horizon development causes reduced infiltration and subsurface interpedon translocation of water, salts, and amorphous materials.
Mast Anchor for Hydraulic Soil‐Sampling Machines
Authors: Mielke L. N. , Wilhelm W. W.
Published: July 2010

Currently, hydraulic soil coring machines allow rapid sample collection to a desired depth under ideal soil conditions; however, under less desirable conditions, sampling can be very time consuming, unsafe, or, at times, impossible. An apparatus was designed and constructed that can be attached to the mast of hydraulic soil sampling machines to anchor the machines to the soil, thus permitting soil sampling when vehicle weight is insufficient to sample to a desired depth. The mast anchor system described is faster and easier to use than the standard system presently used with many hydraulic sampling machines. The parts of the apparatus were an auger, hydraulic motor, guide‐rail frame, slotted‐auger plate, and hydraulic valve and hoses. In one soil sampling situation without additional anchorage, 76.2‐mm diam samples were obtainable to a depth of only 0.75 m, whereas with either standard or mast anchoring, samples were collected to 1.20 m. However, standard anchoring procedures required from 8 to 10 min to install and remove at each sample location, whereas the mast anchor required < 0.5 min.
Enhancement of Thermal Water Vapor Diffusion in Soil
Authors: Cass A. , Campbell G. S. , Jones T. L.
Published: July 2010

The enhancement of water vapor diffusion in soil resulting from a temperature gradient was determined using a transient state thermal conductivity measurement. The method of Parikh et al. (1979) was adapted for this study to allow measurement of the thermal conductivity as a function of temperature, water content, and pressure. The data allowed separation of thermal conductivity from thermally induced latent heat transport. Both the mechanistic enhancement factor η of Philip and de Vries and the phenomenological enhancement factor β of Cary are calculated from the slope of the relationship between thermal conductivity and reciprocal relative pressure. The enhancement factor, η approaches 1 for dry soil and increases rapidly to values around 10 for a sand and a silt loam at water contents above half saturation and temperatures above 22°C. At high water content and 3.5°C, η increased to 15. The inflection point water content for the η vs. saturation curve was about twice as high in silt loam as in sand. Measurements conform well to the pattern predicted by a theoretical examination of enhancement factor behavior. Experimental results were also compared with two recent quantitative models of β from Jury and Letey (1979) and Cary (1979). These model predictions did not agree with measured values, nor did they conform to the theoretical limits of β derived in this paper except at intermediate saturation and temperature values.
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

Replicated 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

Aluminum 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

Although 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

Forest 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

A 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

Geostatistics, 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

The 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

Shallow, 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

Proper 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

A 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

Little 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

Discriminant 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

Water 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

Six 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

The 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

The 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

A 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.
Observed and Predicted Two‐Dimensional Soil Temperature Distributions Under a Row Crop
Authors: Horton R. , Aguirre‐Luna O. , Wierenga P. J.
Published: July 2010

A two‐dimensional soil heat transfer model was developed to compute the soil temperature distribution between rows of crops which partially shaded the soil surface. The model is based on an explicit solution, using CSMP, of the heat conduction equation and allows for time and space dependence of soil thermal properties. Measured soil temperatures were taken as input for the upper boundary. Computed temperature distributions were compared with temperatures measured below a trickle irrigated row crop, which only partially shaded the soil. There was a large variation in the surface and near surface soil temperatures with distance from the row. Ranges of the daily surface soil temperature waves were about 5°C directly below the crop and about 40°C between two crop rows. Around noon the horizontal soil heat flux in the upper soil profile was much greater than the soil heat flux in the vertical direction. Better agreement was obtained between measured soil temperatures and predicted soil temperatures when horizontal heat flux was taken into account.
Transformations of Fall‐Applied Nitrogen‐15‐Labelled Fertilizers
Authors: Aulakh M. S. , Rennie D. A.
Published: July 2010

In conjunction with field studies on gaseous losses of nitrogen, the transformations of fall‐applied 15N‐labelled KNO3 and urea (with and without nitropyrin) were studied in black and dark brown Chernozemic (Typic Udics and Typic Haploborolls) soils during 1980–81 and 1981–82. The amount of fall‐applied N which could not be accounted for in the following spring ranged from 25 to 33% (2 sites) for KNO3 and only 10 and 5% from urea without and with nitropyrin, respectively. These losses occurred during the fall (before the soil was frozen) and in the following spring (after soil thaw) and were primarily due to denitrification. Nitrification of NH+4‐N from applied urea occurred at a slow rate during the cool late fall until freeze‐up and commenced again in early spring when the soil warmed up. Application of nitrapyrin in conjunction with urea delayed nitrification as well as downward movement of fertilizer N in the soil profile and was effective in decreasing the denitrification losses. Immobilization of fertilizer N was minimum under fallow conditions (7%) but ranged from 15 to 21% and 24 to 26% of the applied N as KNO3 and urea, respectively, in wheat stubble fields. Nitrapyrin did not affect the immobilization of fertilizer N or the amount of fertilizer N found in the microbial‐biomass.
Nature and Properties of Pseudoboehmites Formed in the Presence of Organic and Inorganic Ligands
Authors: Violante A. , Huang P. M.
Published: July 2010

Poorly crystalline aluminum oxyhydroxides (pseudoboehmites), with similar x‐ray diffractograms, were synthesized at room temperature at the initial Al concentration of 2 × 10−3 mol L−1 and pH 8.2 in the presence of selected inorganic or organic ligands (1.4 mol L−1 chloride; 0.14 mol L−1 sulfate; 2 × 10−5 mol L−1 citric, tartaric, or tannic acid; 4 × 10−5 mol L−1 tannic acid). Electron micrographs show that these poorly crystalline materials range from fibrous shape to shapeless fine colloids (< 10 nm) or their aggregates before air drying. However, after air drying, the pseudoboehmites consist of fibrillar particles as well as many large aggregates (> 5 µm) even after ultrasonification. The amount of ligands in the precipitates varies from 0.1% for chloride (28 mmol kg−1) to 29.8% for tannate (175 mmol kg−1). The specific surface of the pseudoboehmites ranges from 30.0 hm2 kg−1 to 58.0 hm2 kg−1 due to the presence of foreign ligands which promote structural distortion in the precipitation products and/or aggregation of the particles. The PZC values of the pseudoboehmites formed in the presence of inorganic and organic ligands vary from 8.0 to 9.3. The net positive charge of the poorly crystalline aluminum oxyhydroxides varies with the kinds of ligands present during their precipitation. The data obtained in this study show that pseudoboehmite samples formed under the varying ionic environments differ significantly in their chemical composition and surface properties.
Simultaneous Determination of Calcite Surface Area and Content in Soils
Authors: Suarez D. L. , Wood J. D.
Published: July 2010

A method to simultaneously determine calcite surface area and content in soils has been developed. The proposed procedure is based on rates of CO2 production upon reaction of soil with buffered acid solutions under controlled conditions. A pressure transducer connected to a chart recorder allows determination of soil calcite dissolution rate, which is directly proportional to calcite surface area. Sample size typically ranges from 0.3 to 10.0 g. The coefficient of variation for surface area was 0.05, based on nine replicated analyses of the same soil.
Soil Properties in Creosotebush Communities and their Relative Effects on the Growth of Seeded Range Grasses
Authors: Cox Jerry R. , Parker James M. , Stroehlein Jack L.
Published: July 2010

Soils were collected to 15 cm along the four cardinal directions at three locations around 10 creosotebush [Larrea tridentata (DC.) Cov.] plants at five sites in the southwestern United States. The sampling locations were: (i) at the canopy center, (ii) along the outer canopy edge, and (iii) in open areas between plant canopies. A portion of the soil from each sampling location was analyzed for particle size distribution, pH, EC, CaCO3, Ca, K, Na, Mg, NO‐3‐N, organic C, available P, and Mn. The remaining soil from each sampling location was seeded with either Lehmann lovegrass (Eragrostis lehmanniana Nees) or blue panicgrass (Panicum antidotale Retz.). Grass seeds were germinated and grown for 42 d in a greenhouse. Nitrate was significantly (∝ = 0.05) lower in open areas between creosotebush canopies than near the shrub canopy center at all sites. Grass seedling growth decreased as the distance from the canopy center increased and seedling growth was highly correlated with nitrate concentrations. Spatial distribution patterns for the other measured soil properties did not occur in a consistent fashion across all sampled sites. The action of mechanical tillage to limit creosotebush competition, and corresponding dilution of NO‐3‐N in the soil volume, may reduce the probability of establishing perennial grasses.
Preparation of Large Core Samples from Stony Soils
Authors: Buchter B. , Leuenberger J. , Wierenga P. J. , Richard F.
Published: July 2010

A method was developed to take large, undisturbed soil cores in stony soils. An undisturbed soil core was surrounded with concrete, frozen to −22°C and cut to shape with a diamond circular saw, leaving only core sample. The core sample was surrounded with paraffin to maintain its shape.
Comparison of Field Denitrification Rates Determined by Acetylene‐Based Soil Core and Nitrogen‐15 Methods
Authors: Parkin Timothy B. , Sexstone Alan J. , Tiedje James M.
Published: July 2010

A soil core method to measure field denitrification rates was evaluated by comparing the results with denitrification rates measured by the 15N difference method. In the core method, acetylene amended air was recirculated through an undisturbed soil core and short‐term (ca. 1 h) nitrous oxide production monitored. Denitrification rates were obtained on soil cores from two field sites and a set of sieved, repacked soil cores in a laboratory incubation. Cumulative N‐losses were estimated by interpolating between sample dates. Denitrification rates obtained by the core method were found to approximate a log normal distribution at both sites studied and at all sampling times. Statistical calculations appropriate for this distribution resulted in improved estimates of the mean rates and confidence intervals. For the 15N difference method, 15N enriched nitrate was added to microplots of 30 cm diameter and the total gaseous losses were estimated by considering the change in the total nitrate pool, the isotope ratio of that pool and the 15N not recovered from the microplots. Experiments were conducted over periods of 32 to 45 d on sandy loam and clay loam soils, respectively. Denitrification rates from the acetylene‐core method were not significantly different than the estimates by the 15N method. Denitrification rates as measured by both methods were highly variable.
Shrink‐Swell Potential of Montmorillonitic Soils in Udic Moisture Regimes
Authors: Karathanasis A. D. , Hajek B. F.
Published: July 2010

Thirty‐two montmorillonitic soil pedons representative of Vertisols, Inceptisols, and aquic, typic, or vertic subgroups of Alfisols and Ultisols in the udic moisture regime of Alabama were evaluated for their shrink‐swell properties. Soil shrink‐swell potential was evaluated on control section samples from coefficients of linear extensibility (COLE) measured by thermo‐mechanical analysis (TMA), percent volume change (PVC) of remolded samples measured by a micrometer, interlamellar shrinkage (IS) determined by x‐ray diffraction analysis, and from field expression of soil cracking. No significant differences in COLE, PVC, IS, smectite or clay content were encountered between soils with and without vertic characteristics. Discrepancies were found between laboratory measured and field observed shrinking potential of aquic/typic/vertic Ultisols primarily due to lack of wide cracks. The poor field expression of cracking in montmorillonitic Hapludults was better explained by a combination of physical and morphological characteristics such as texture and thickness of the surface layer, size and type of structural units, solum thickness and depth to Cr, soil moisture deficit, drainage and vegetation than by variation in physical, chemical, or mineralogical properties. At present, classification of montmorillonitic Hapludults in vertic subgroups is proscribed by lack of evidence of wide or deep cracking. Modifications in the current vertic subgroup definition are suggested to account for agronomic and/or engineering limitations of these soils.
Soil‐Saprolite Profiles Derived from Mafic Rocks in the North Carolina Piedmont: II. Association of Free Iron Oxides with Soils and Clays
Authors: Rice T. J. , Weed S. B. , Buol S. W.
Published: July 2010

The association of free Fe oxides with soils and clays from two Enon sandy loam (Ultic Hapludalfs, fine, mixed, thermic) soil‐saprolite profiles was studied. Goethite was the dominant Fe oxide identified. Lepidocrocite was detected in trace amounts in some samples. FeCBD/clay ratios were highest in the epipedons of these soils suggesting the concentrating of Fe oxides as a result of aluminosilicate mineral weathering. External (BET‐N2) surface area measurements of non‐deferrated and deferrated clays were analyzed in conjunction with electron micrographs of selected clay fractions to determine the association of free Fe oxides with aluminosilicate clays as a function of depth in the profile. Free Fe oxides were found to exist mainly as small, discrete clusters in the A and B horizons of both profiles and specific of the clay surface decreased as a result of treatment for Fe removal. However, external surface areas increased for the saprolite (Cr) horizon clays after deferration. One subfraction identified as having an increase in surface area after deferration was fine clay from the Cr2 horizon, Enon (metagabbro) profile. Chemical data and electron micrographs suggest that either partial dissolution of small, poorly crystalline aluminosilicate clays or removal of some Fe or non‐Fe oxide aggregating agent results in breakdown of the fine clays into smaller particles of higher net specific surface.
Automated Analysis of Nitrous Oxide
Authors: Parkin T.B.
Published: July 2010

An autosampler was developed to interface with a gas chromatograph for N2O analyses. The sampler was comprised of a modified fraction collector and pneumatic valves all controlled by a microprocessor unit. Cost of the autosampler system including the fraction collector was estimated to be less than $3500. The sampler was designed to analyze gas samples stored in rubber‐stoppered, glass vials. Use of vials resulted in a slight loss of sensitivity due to dilution and absorption of N2O; however, accuracy was the same as could be obtained by manual syringe injections.
Formation of Methyl Nitrite in Soil Treated with Nitrous Acid
Authors: Magãlhaes A. M. T. , Chalk P. M. , Rudra A. B. , Nelson D. W.
Published: July 2010

The formation of methyl nitrite was detected when two clay soils were treated with nitrous acid (260 ± 20 mg N kg−1 soil) in the dark in a closed chamber. The presence of the gas was positively identified by mass spectrometry. There was a consistent trend with time in the concentrations of methyl nitrite in the atmospheres above the soils. A rapid buildup occurred following addition of nitrous acid, but this was soon followed by a gradual decline in concentration. The peak concentrations occurred approximately 15 min or 30 min after nitrous acid addition, and 5‐h concentrations were < 50% of peak concentrations. Methyl nitrite was formed under mildly to moderately acid conditions (pH 6.3 and 4.8) at −33 kPa soil water potential. The results indicate that methyl nitrite may form under conditions encountered in the field, and that soil can be a sink as well as a source of methyl nitrite.
Hydrolysis of Trimetaphosphate in Soils
Authors: Busman L. M. , Tabatabai M. A.
Published: July 2010

Trimetaphosphate (TMP), a cyclic polyphosphate that is not sorbed by soils, is hydrolyzed by a series of biochemical reactions to yield triphosphate, pyrophosphate, and orthophosphate; phosphates that are sorbed by soils. In addition to its hydrolysis to triphosphate in soils by the enzyme trimetaphosphatase (trimetaphosphate hydrolyase, EC 3.6.1.2), TMP is hydrolyzed chemically by metal ions such as Ca2+ and Mg2+. A method was developed for assaying the activity of trimetaphosphatase and for determining the rate of nonenzymic (chemical) hydrolysis of TMP in soils. The method involves incubating 1 g of soil with 3 mL buffered (100 mM Tris) 25 mM TMP at 37°C for 5 h followed by determination of the unaltered substrate. Steam‐sterilized soil is used as a control to account for the amount of TMP hydrolyzed nonenzymically. Trimetaphosphatase activity in soils was maximum at a buffer pH of 8 and a temperature of 40°C. Nonenzymic hydrolysis of TMP increased up to the highest incubation temperature (80°C) tested. Trimetaphosphatase in three Iowa surface soils showed apparent Km values ranging from 6.8 to 7.2 mM TMP, Vmax values from 590 to 1200 mg TMP‐P hydrolyzed kg−1 soil 5 h−1, and energy of activation values from 17 to 26 kJ mol−1. The activation energy values of the nonenzymic hydrolysis ranged from 29 to 39 kJ mol−1. Enzymic and nonenzymic hydrolysis rates in the six soils used ranged from 231 to 928 and from 101 to 888 mg TMP‐P kg−1 soil 5 h−1, respectively. Formaldehyde and EDTA inhibited, and toluene had no effect on, trimetaphosphatase activity in soils. The addition of Ca2+ and Mg2+ increased nonenzymic hydrolysis rates in two soils tested with Ca2+ being twice as effective as Mg2+.
Organic Carbon in Soils of North Central United States
Authors: Franzmeier D. P. , Lemme G. D. , Miles R. J.
Published: July 2010

Organic carbon contents in the upper 0.2 m and upper 1.0 m of soils in the 12‐state North Central Region are presented in this study with tables and maps. The information was summarized by pedologists in each state from laboratory analyses of pedons typical of a soil series and the areal composition of soil associations by soil series. Much of the data was gathered in connection with the cooperative soil survey. Associations of mineral soils range in carbon content to a depth of 1 m from about 2 kg m−2 in the Badlands of North Dakota to 21 kg m−2 in some poorly‐drained, fine‐textured soils of eastern North Dakota. Organic soils contain about 75 kg m−2. The average for all soils of the region is 11.7 kg m−2 carbon. Organic C levels are related largely to parent material, natural vegetation, and topography factors in this geographic region. The information contributes to our knowledge of the amount of carbon in soils, one of the important global carbon reservoirs, which is of interest to those who study atmospheric CO2 changes. It is also important relative to soil management operations such as herbicide application.
Iron Distribution in a Developmental Sequence of Soils from Mica Gneiss and Schist
Authors: Rebertus R. A. , Buol S. W.
Published: July 2010

Upland residual soils formed from mica gneiss and schist in the Piedmont and Blue Ridge provinces of North Carolina represent developmental sequences where particle‐size class, profile development, and mineralogy are related to landscape position and slope. In this study the distribution of total and free iron in 10 Hapludult and Dystrochrept pedons is examined and interpreted with respect to degree of profile development. Primary mineral alteration and B horizon free iron/total iron ratios vary nearly systematically with particle‐size class and solum thickness. The latter two parameters were found to be good indicators of degree of profile development and hence of relative soil age. The free iron/total iron ratio was found to be a particularly sensitive indicator of relative soil development. The ratio reflects the degree of primary mineral alteration, the amount of clay formed, as well as the pedogenic process of illuviation. The B horizon ratios are much better indicators of relative soil development than those from either C or A horizons. Ratios of free iron/total iron in A horizons are influenced by downslope movement of surficial material, the low extractability of iron oxides of large particle size, and clay content differences. Free iron/total iron ratios of C horizons are dependent on sampling depth, the amount of clay formed, and the degree of illuviation that has occurred below the solum. All soils had oxidic ratios (%Fe2O3 + %gibbsite/%clay) > 0.2; however, all but one was excluded from the oxidic mineralogy class due to having >40% mica. A simple free iron/total iron ratio in B horizons, which is systematically related to the degree of weathering of primary minerals and the degree of morphological soil development, better serves as soil family criteria than the present % Fe2O3 + % gibbsite/% clay.