bluuebunny/crossref_metadata_2025 huggingface dataset:
Particle Size Analysis by Hydrometer: A Simplified Method for Routine Textural Analysis and a Sensitivity Test of Measurement Parameters
Authors: Gee G. W. , Bauder J. W.
Published: July 2010

A simple modification of the Day (1965) hydrometer method is suggested for routine textural analysis. The simplified method requires no calibration, graphs or tables and uses a weighted average of the 1.5‐hour and 24‐hour readings to determine the 2µm clay fraction. The relationship is:
urn:x-wiley:03615995:saj2sssaj197903615995004300050038x:equation:saj2sssaj197903615995004300050038x-math-0001 where

P2µm = summation percentage for the 2µm clay fraction.

P24, P1.5 = summation percentage for settling time of 24 hour and 1.5 hour, respectively.

K = weighting factor, used to approximate the actual relation of the summation percentage curve over the clay percentage range of interest.

This equation was found to be satisfactory in the range of 5% ⩽ P2µm ⩽60% by weight for over 70 North Dakota soil and subsoil materials when K=0.876.

Sensitivity analyses were performed for the Day, Bouyoucos, and the Simplified Day hydrometer methods to determine which of several measured parameters contribute to the greatest possible error; hence which parameters should be controlled with the greatest precision. The hydrometer scale reading error contributes more error than any other single parameter.
Thermal Diffusivity and Conductivity of Moist Porous Media
Authors: Parikh R. J. , Havens J. A. , Scott H. D.
Published: July 2010

An unsteady‐state method was used to determine thermal diffusivities and conductivities of nominally 250 µm glass beads and a silt loam soil over a range of moisture contents. The thermal diffusivity of the beads was found to increase from 0.0013 cm2/sec for dry beads to 0.003 cm2/sec at 5% volumetric moisture content, but is only weakly affected by moisture contents > 5%. The thermal diffusivity of the silt loam soil increases from 0.0022 cm2/sec for dry soil to 0.0042 cm2/sec at 30% volumetric moisture content, above which it remains essentially constant with increasing moisture content. The thermal conductivities of both porous media increase with moisture content over the entire wetness range, the thermal conductivity of the glass beads increasing from 0.53 mcal °C−1 cm−1 sec−1 to 1.97 mcal °C−1 cm−1 sec−1, and that of the silt loam soil from 0.57 mcal °C−1 cm−1 sec−1 to 2.79 mcal °C−1 cm−1 sec−1. Measured thermal conductivities of the glass bead media were in excellent agreement with values calculated using deVries' method.
Comparison of Various Methods of Sampling Soil Water for Determining Ionic Salts, Sodium, and Calcium Content in Soil Columns
Authors: Barbarick K. A. , Sabey B. R. , Klute A.
Published: July 2010

At the end of a column experiment studying the flux of ionic salts and Na+ from applied sewage effluent, the salt, Na+, and Ca2+ contents were compared in extracts from porous cups, from the soils around the cups, and saturated paste extracts after the column soils were air‐dried. The salt level in the porous cup samples and in the moist soil samples obtained directly at the end of the experiment, and the Na+ content in the porous cup and in saturated paste extracts that were equilibrated for 48 hours were highly correlated.
Infiltration of Soils as Affected by the Pressure and Water Content at the Time of Compaction
Authors: Akram Mohd. , Kemper W. D.
Published: July 2010

Infiltration rates, volume reduction, and bulk densities of soils were determined on soils as a function of compacting pressures and water content at the time of compaction.

Maximum compaction generally occurred when the soils were packed at water contents near field capacity.

When compacting loads were < 1 kg/cm2 the minimum bulk densities occurred when soils had water contents of about one half field capacity, indicating that surface tension of water films in the soils plays a major role in cohesiveness and stabilization against compaction under these conditions.

Compacting loads of 3.46 kg/cm2, at field capacity on sandy loams and finer textured soils, reduced infiltration rates to < 0.1% of values obtained after these soils had been compacted when they were air dry. In a loamy sand soil this reduction was to about 1%.

The low infiltration rates following compaction were increased by wetting and drying, although several cycles of wetting and drying did not raise the infiltration rate to the level observed before packing.

Freezing and thawing cycles also increased the infiltration rates of previously compacted soils. Most of the change took place in the first freezing and thawing cycle.

The large changes in infiltration rates using achievable levels of compaction at the “optimum” water contents indicate that compaction can play a major role in the management of water in ditches, reservoirs, furrows, and watersheds.
An Analytical Solution to Solute Transport Near Root Surfaces for Low Initial Concentration: I. Equations Development
Authors: Cushman John H.
Published: July 2010

In Part I of this two part paper the governing differential equation for radial flow to a root with constant moisture properties, is transformed into a nondimensional and more useful form. An analytical solution to the differential equation with two appropriate sets of boundary conditions is developed. The solution can be expressed as an infinite series of Bessel functions, powers of nondimensional distance and an exponential.

Equations for total and diffusive nutrient uptake are developed for both growing and nongrowing roots. Nondimensional equations are also presented for the various components of the nutrient flux (diffusive, convective, and total).

The equation for total nutrient uptake for a root growing at a rate f(t) such that f(o) = Lo (initial length), is examined in detail when f(t) is an exponential.
Soybean Plant Growth, Nodulation, and Nitrogen Fixation as Affected by Root Temperature
Authors: Lindemann W. C. , Ham G. E.
Published: July 2010

The objective of this study was to investigate the influence of root temperature, Rhizobium japonicum strain, host variety, and plant age on soybean growth, nodulation, and N2 fixation.

Soybean plants were grown in sand‐filled Leonard jars and watered with N‐free nutrient solution. Soybean root temperatures were held constant at 15, 20, 25, and 30°C in a growth chamber environment. At harvest, plant height and weight, nodule number and weight, and acetylene reduction activity were measured.

Interactions between root temperature, R. japonicum strain, and soybean variety were complex and changed with plant age. Temperature by strain interactions were more common than temperature by variety, variety by strain, or temperature by variety by strain interactions. Plant height was solely dependent on root temperature, but nodulation and acetylene reduction activity parameters depended on temperature, strain, and variety. Such interactions were more complex at later growth stages.

Maximum plant dry weight and nodule number occurred at 25°C. Nodule weight and acetylene reduction activity were greater at 25°C than at the other root temperatures early in plant growth (3–4 weeks after planting.) However, 5–6 weeks after planting, these parameters were greater at 20° than at 25°C. Apparently more nodules were formed at 25°C, but eventual nodule development, size and acetylene reduction activity was greater at 20°C. Nodules also degenerated sooner at 25°C. Nitrogen fixation significantly increased plant growth over that of the uninoculated controls except at 15°C. The confined root environment of the Leonard jar may have restricted further nodulation after 5 weeks from planting and may have influenced nodule weight and acetylene reduction activities as well as nodule numbers.
The Influence of Nitrate, Nitrite, and Oxygen on the Composition of the Gaseous Products of Denitrification in Soil
Authors: Firestone M. K. , Smith M. S. , Firestone R. B. , Tiedje J. M.
Published: July 2010

[18N]‐N2O produced by denitrification of 18NO‐3 in soil slurries readily exchanged with nonlabeled pools of added N2O. This supports the role of N2O as a free, obligate intermediate of denitrification in soils. The observation that N2O diffuses freely from the site of active denitrification in soils means that any factor which produces a change in the relative rate of N2O reduction compared to the rate of N2O production can alter the proportion of N2O and N2 resulting. Increased concentration of NO3‐ and NO2‐ resulted in increased production of N2O relative to N2 as the product of denitrification. The influence of NO2‐ was much stronger than that of NO3‐, with low concentrations of NO2‐ causing N2O to become a significant product of denitrification. This suggests that NO2‐, not NO3‐, may be the influential species. Additions of small quantities of O2 (0.02 atm) caused a large decrease in denitrification activity and resulted in a significant increase in the N2O/N2 ratio.
Effect of Depth of Lime Incorporation on the Growth of Corn on an Oxisol of Central Brazil
Authors: Gonzalez‐Erico E. , Kamprath E. J. , Naderman G. C. , Soares W. V.
Published: July 2010

High Al saturation is one of the limiting factors to intensive cropping of many soils in the Cerrado of Brazil. A field study on the effect of lime rate and depth of incorporation on growth of corn (Zea mays L.) was conducted on an Oxisol (Typic Haplustox) at Brasilia. Lime rates used were 0, 1, 2, 4, and 8 tons CaCO3/ha and depths of incorporation were 15 and 30 cm. Incorporation of 4 tons of CaCO3 to a depth of 30 cm reduced Al saturation from 72% to < 5% on a soil which initially had 1.1 meq Al/100 cm3. Concentrations of soil solution Al decreased to very low levels at pH 5.5.

Grain yields of three successive corn crops were increased by liming. Incorporation of lime to a depth of 30 cm resulted in higher yields than incorporation to a depth of 15 cm. Application of MgSO4 to the acid soil increased yields above the nonlimed treatment.

Yield responses to liming were due to improved Mg nutrition and neutralization of toxic Al. Root length was increased considerably in the 0‐ to 15‐cm depth and doubled in the 15‐ to 30‐cm depth when Al was neutralized by liming. Increased root development in the 15‐ to 30‐cm depth of the deep lime treatments resulted in greater water utilization from this depth and decreased the detrimental effects of moisture stress at tasseling on corn yields.
Jack Pine Biomass Accretion on Shallow and Deep Soils in Minnesota
Authors: Green D. C. , Grigal D. F.
Published: July 2010

Biomass accretion and standing biomass of jack pine (Pinus banksiana Lamb.) were studied on sballow soils over three different bedrock types; granite, greenstone, and gabbro; and on deep till in northeastern Minnesota. The shallow soils were either Lithic Udorthents or Lithic Dystrochrepts and the deep soils were Typic Dystrochrepts. Individual tree biomass accretion was described by combining diameter‐age and biomass‐diameter relationships. At age 50, the mass of an average surviving tree on till would be 117 kg, and of trees growing on shallow soil over greenstone, granite, and gabbro would be 88, 68, and 57 kg, respectively. As an index of productivity, this ranking agrees with that of rock types based on site index (14.3, 11.2, 10.2, and 9.3 m at 50 years, respectively). Although these results imply differences in yield, the average overstory biomass did not differ between shallow soils, with an average of 81,000 kg/ha, compared to a significantly greater 147,000 kg/ha on the deep till. Stand biomass accretion was estimated by adjusting the relationship between stocking and age, and diameter and age, from a normal yield table to fit the present status of the sampled stands on each rock type. These data were then combined with a tree biomass‐diameter function, yielding a relationship between stand biomass and age for each rock type. The estimated biomass accretion was similar on shallow soils but greater mass occurs at any age on deep soils.
Kinetics of Dissolution of Phosphate Rocks in Soils
Authors: Chien S. H. , Clayton W. R. , McClellan G. H.
Published: July 2010

A modified Elovich equation in the form of Ct = C0 − (1/β)ln (αβ) − (1/β) ln t was derived to describe the kinetics of dissolution of three phosphate rocks (North Carolina, central Florida, and Tennessee) in three soils (one soil from Florida and two Nigerian soils). The equation fitted the experimental data the best among various models of kinetics. Comparisons of dissolution rates of various phosphate rocks in a given soil or a given phosphate rock in various soils can be made by comparing the values of three parameters—C0, α, and β—in the equation where C0 is the maximum P concentration in the soil solution that a phosphate rock can provide in a soil (Ct is the P concentration at time t), and α and β are constants. It was found that C0 increased as α increased and/or β decreased in a given system.

Temperature was found to have no significant effect on the dissolution of phosphate rock in the soil. This implies that phosphorus retention by the tropical soils treated with phospate rock may be much less affected by temperature as compared with water‐soluble P fertilizers such as concentrated superphosphate.
Gaseous Nitrogen Evolution During Nitrification of Ammonia Fertilizer and Nitrite Transformations in Soils
Authors: Smith C. J. , Chalk P. M.
Published: July 2010

The biological oxidation of NO2‐ is inhibited when alkaline‐hydrolyzing N fertilizers are band‐applied to soils, and NO2‐ may accumulate. Nitrogenous gases can be evolved with NO2‐ is added to soil. The aim of the work described here was to determine if gaseous‐N losses could occur via chemical transformations of NO2‐ during nitrification in soils treated with NH3 fertilizer.

Evolution of N2, N2O, and NO + NO2 occurred during nitrification in three soils treated with aqueous NH3. Losses occurred when measured soil pH was > 7.5. The highest gaseous‐N loss amounted to 16.5% of applied‐N (1156 µg N applied/g of soil) in a calcareous soil incubated for 28 days at 30°C. Nitrogen was the major gaseous form of N evolved in all soils. In two soils, NO2‐ did not accumulate to more than 13 µg N/g of soil, but substantial N2 emission was measured. Addition of the nitrification inhibitor, nitrapyrin, with the fertilizer, prevented NO2‐ accumulation without preventing nitrification. This treatment prevented N2O evolution and markedly reduced loss of N2 and NO + NO2.

Evolution of N2, N2O, and NO + NO2 occurred in the three soils following NO2‐ addition. Loss of N2 was very sensitive to soil pH, and markedly increased with increasing acidity. However, N2 was readily evolved when soil pH was slightly alkaline. Evolution of NO + NO2 was inversely related to pH, but N2O loss was highest in the most alkaline soil (pH 8.4). The marked similarities within individual soils of the patterns of gaseous‐N losses obtained for NH3 and NO2‐ treatments, strongly suggest that similar processes were operating. Gaseous‐N evolution was similar in γ‐irradiated and nonirradiated soils treated with NO2‐. These results, together with the effect of nitrapyrin, suggest that gaseous‐N losses can occur via chemical transformations of NO2‐, when the competitive biological oxidation of NO2‐ by Nitrobacter is inhibited.
Predicting Height Growth of Yellow‐poplar from Soils and Topography in Southeastern Ohio
Authors: Munn Larry C. , Vimmerstedt John P.
Published: July 2010

Intensive forest management requires an accurate knowledge of site productivity. Where inadequate stocking prohibits direct measurement of site quality, predictive models based on soils and topography may be used to estimate site potential. A predictive model was developed for estimating height growth of yellow‐poplar (Liriodendron tulipifera L.) on a Muskingum‐Neotoma‐Berks soils complex (Typic Dystrochrepts and Ultic Halpludalfs) in Tar Hollow State Forest, Ross County, Ohio. Measurements were made of selected topographic and soil physical and chemical factors for 203 dominant or codominant yellow‐poplars in 39 plots. Observed variation in site index within the mapping unit was 7.0 m. Multiple regression equations of the form: LOG(tree height) = C0 + B0 (1/AGE) + B1V1 + … + BnVN. were used to construct prediction equations. Significant correlations (p = 0.05 level) were found between tree height (with age accounted for), and the following variables; slope position; A horizon thickness; depth to the B2 horizon; depth to a restriction; corrected aspect (minor angle from the southwest); soil pH and lime test index; kg/ha of available P (p = 0.10 level) and Mn; kg/ha of exchangeable Ca, Mg, and K; percent base saturation; and soil organic matter. Approximately 65% of the observed variability in tree height was accounted for by the regressions.
A Semi‐Micro Method for Determining Total Nitrogen in Soils and Plant Material Containing Nitrite and Nitrate
Authors: Douglas L. A. , Riazi A. , Smith C. J.
Published: July 2010

A convenient semi‐micro procedure for total N analysis (including NO2‐ and NO3‐) of soil and plant material is described. The sample plus KMnO4, H2SO4, and Fe is initially placed in a test tube and heated in a water bath (90°C). Final digestion with concentrated H2SO4 occurs in a heated Al (to 370°C) block. The NH4+ content of the cooled tube contents is determined by steam distillation. This method allows simultaneous digestion of 60 samples, is inexpensive, accurate and precise, and includes NO2‐ and NO43‐ in the total N estimation.
Bicarbonate‐Extractable Phosphorus in Fresh and Composted Dairy Manures
Authors: Elias‐Azar K. , Laag A. E. , Pratt P. F.
Published: July 2010

The availability of the P from manure and from KH2PO4 was estimated by extraction with NaHCO3 following incubation in soils for 15, 30, and 45 days. In two alkaline sandy soils the availability of the P from manures was equal to that from KH2PO4. The availability of manure P relative to P from KH2PO4 increased as the pH increased and as the sand content increased, i.e., as the clay plus silt increased. The relative availability of the manure P increased in some soils as the time of incubation increased.
Modeling Vapor Losses of Soil‐Incorporated Triallate
Authors: Jury W. A. , Grover R. , Spencer W. F. , Farmer W. J.
Published: July 2010

Vapor losses of triallate [S‐(2,3,3‐trichloroallyl) diisopropylthiocarbamate] incorporated into two soils with widely different organic matter contents were measured in the absence and presence of evaporating water. Adsorption isotherms (relating triallate solution concentrations to adsorbed triallate) were used to compare predicted and measured transport of triallate by mass flow and diffusion. With San Joaquin sandy loam, volatilization rate was greater when water was evaporating than when evaporation was suppressed but with Flanagan silt loam packed to a much lower bulk density, vapor loss was nearly the same in the presence and absence of evaporation. Total vapor losses during the 29‐ or 30‐day, period were 2.97 and 3.76% of the amounts applied from San Joaquin sandy loam and 3.72 and 3.80% from Flanagan silt loam without and with evaporation, respectively. Good agreement was observed between the total measured triallate vapor flux with evaporation and the convective mass flux calculated from the product of the solution concentration below the surface times the water evaporation flux.
Effect of Exchangeable Sodium Percentage, Cation Exchange Capacity, and Soil Solution Concentration on Soil Electrical Conductivity
Authors: Shainberg I. , Rhoades J. D. , Prather R. J.
Published: July 2010

The electrical conductivity of eight soils was measured as a function of the solution electrical conductivity over a wide range of salt concentration and salt composition. The soils electrical conductivity increased nonlinearly with respect to the equilibrium solution electrical conductivity in the low range of salt concentration (< 2–3 mmho/cm). In the higher salt concentration range, straight line relationships were obtained. The shape of the curves was explained by the inclusion of a solid‐water in series element in the conductance model. The effect of the soil ESP on the electrical conductivity curve parameters is slight and is not significant when the electrical conductivity method is used to survey soil salinity.
Nature and Extent of Directly Measured Denitrification Losses from Some Irrigated Vegetable Crop Production Units
Authors: Ryden J. C. , Lund L. J.
Published: July 2010

Directly measured denitrification N flux from field study sites in irrigated vegetable production units, ranged from 0.024 to 1.92 kg N ha−1 day−1 subsequent to irrigation, and values up to 3.60 kg N ha−1 day−1 were observed after rain. The N denitrification flux was measured as nitrous oxide (N2O) evolution from locations within each study site treated with actylene (C2H2) to establish C2H2 concentrations close to 1% (vol/vol) in the soil pore space. Denitrification N flux showed a pronounced dependence on soil‐water suction. Peak fluxes were observed for suctions between 50 and 100 mbars and were associated with field‐measured Eh (redox potential) values between 400 and 650 mV. Flux decreased to < 0.096 kg N ha−1 day−1 when suction increased above 250 mbars and Eh returned to values > 650 mV. Nitrate in extracts of soil cores sampled concurrently with measurements of gas evolution appeared to have little effect on the magnitude of the N flux. Fluxes of at least 1.20 kg N ha−1 day−1 were observed for nitrate levels as different as 2 and 33 µg N/g. The major impact of increased soil nitrate concentrations was in shifting the distribution of denitrification products in favor of N2O. Annual dentrification N loss from each study site, estimated from direct measurements, compared favorably with the indirect estimate based on the imbalance in the N budget. Direct estimates ranged from 95 to 233 kg N ha−1 year−1 (14 to 52% of N input), and coupled with other directly measured inputs and outputs of N provided an 80 to 95% accountability of the N applied. Nitrous oxide emission comprised 13 to 20% of the total denitrification loss at sites with pH above 7, but values of approximately 30% were observed at more acid sites.
Fate of Tagged Nitrogen Fertilizer Applied to Irrigated Corn
Authors: Olson R. V.
Published: July 2010

A field experiment was conducted for 2 years with ammonium sulfate tagged with 5.93 atom % 15N to determine the fate of N fertilizer applied to sprinkler‐irrigated corn (Zea mays L.). All areas of triplicate, 356‐cm square plots were treated with 50 or 150 kg tagged N/ha. N fertilizer used by the crop and that remaining in the top 240 cm of soil were measured. NH4+‐N and NO3‐‐N in the 0‐ to 10‐cm layers after the second harvest also were determined. Grain yields in 1976 did not differ significantly. In 1977 response to N was significant, but responses to two N rates did not differ significantly.

Only about one‐fourth of the N fertilizer at either rate was removed by the grain. Amounts in the soil were in proportion to amounts applied and about three times more after 2 years than 1 year, reflecting the N in crop residue from the first crop. The N balance indicated losses from the system of 17 to 18% of the N applied during the 2 years, after correcting for apparent errors. Fertilizer did not significantly alter amounts of soil N used by the crop but total N uptake increased with each fertilizer increment. There was no priming effect on mineralization of indigenous soil N. Comparng the 15N and difference methods for calculating fertilizer N uptake showed that the difference method varied more and showed significantly less uptake in one case.

From 65 to 73% of the N fertilizer remaining in the soil was in the 0‐ to 10‐cm layer. Depth of movement was related to amount applied, varying from 20 cm with 50 kg after 1 year to 240 cm with 150 kg applied each year for 2 years. Some of the N with the 150‐kg rate may have leached below 240 cm after 2 years, but there appeared to be no leaching from the measured zone in other cases so losses from the system must have been by denitrification.

Most of the N fertilizer in the 0‐ to 10 cm‐layer after 2 years was immobilized with only 4.4 to 4.7% remaining in the NH4+ and NO3‐ forms. However, there was about seven times more inorganic N in the soil originating from fertilizer than came from indigenous soil N, which confirms that residual fertilizer N is more likely than indigenous N to be present in inorganic forms.

Amounts of fertilizer N found in grain and lost were proportional to amounts applied. The 150 kg N/ha rate gave no higher grain yields than 50 kg N/ha rate, but resulted in much greater crop removal, gaseous loss, and downward movement into the soil profile.
Reaction of MnEDTA Applied Alone or with Ammonium Polyphosphate Fertilizer to Soils
Authors: Mortvedt J. J.
Published: July 2010

Manganese ethylenediamine tetraacetate (MnEDTA) applied alone to some low‐Mn, high‐Fe soils generally is not an effective Mn source for plants; apparent substitution of other soil cations for Mn in MnEDTA decreases plant availability of applied Mn. A laboratory study was conducted to estimate cation substitution for Mn in MnEDTA by determining changes with time in H2O‐soluble cations in treated soil. Four moist soils (pH 5.4 to 7.7) were treated with MnEDTA at rates of 0, 25, and 100 ppm Mn; soils were aerobically incubated up to 148 days. In addition, MnEDTA was applied to these soils with 10‐15‐0 (10‐34‐0 oxide basis) fluid polyphosphate fertilizer at rates of 1,500 ppm P and 100 ppm Mn. The application rate simulated that in soil around a fertilizer band of 10‐15‐0 containing 1% Mn at a rate of 50 kg of P/ha (100 lb of P2O5/acre).

Water‐soluble Mn increased with MnEDTA rate in all soils just after application but decreased with time to the level of untreated soils. In soils treated with MnEDTA alone, H2O‐soluble Fe increased with time in acid soils, and H2O‐soluble Ca increased in limed or calcareous soils, suggesting substitution of these cations for Mn in the EDTA molecule. Levels of H2O‐soluble Mg, Zn, and Cu in all soils were not affected by application of MnEDTA.

Application of MnEDTA with 10‐15‐0 reduced the apparent rate of cation substitution for Mn in MnEDTA by precipitation of competing cations in soil. Thus, Mn in MnEDTA should remain available to plants for a longer time with band application in fluid polyphosphate fertilizers than with mixed application alone or with other fertilizers to soil.
Hexachlorobenzene: Its Vapor Pressure and Vapor Phase Diffusion in Soil
Authors: Farmer W. J. , Yang M. S. , Letey J. , Spencer W. F.
Published: July 2010

The vapor pressure of hexachlorobenzene (HCB), measured with the gas saturation technique, was related to the temperature by the equation log10p = 12.94 − (5279/T) giving HCB vapor pressure values from 0.420 × 10−5 to 22.4 × 10−5 mm Hg over the temperature range 15 to 45° C. The heat of vaporization of HCB was calculated to be 24.2 kcal/mol. The vapor pressure data was used to measure the vapor phase diffusion of HCB in soil using a vapor‐diffusion cell. The steady‐state vapor diffusion of HCB in soil was directly related to soil air‐filled porosity and was therefore greatly reduced by increased soil bulk density and increased soil water content. The apparent steady‐state HCB diffusion coefficient was linearly related to the soil porosity term, Pa10/3 / PT2 where Pa is the soil air‐filled porosity and PT is the total soil porosity. The calculated diffusion coefficient in air for HCB was 1.0 × 104 cm2/day.
Bulk Densities of California Soils in Relation to Other Soil Properties
Authors: Alexander E. B.
Published: July 2010

Analyses of 721 samples from inorganic horizons of upland and alluvial soils in seven orders were utilized to develop equations for predicting soil bulk density at 1/3‐bar water content. The minimum standard errors of estimate (0.14 g cm−3, r2 = 0.723, for upland soils and 0.11 g cm−3, r2 = 0.672, for alluvial soils) were obtained with functions of organic carbon content, 15‐bar water content, the ratio of 15‐bar water to clay, silt and sand contents, parent material, calcium carbonate equivalent, mean soil horizon depth, and for alluvial soils, soil drainage class too. Functions of electrical conductivity of saturation extract and, for alluvial soils, mean soil horizon depth did not lower the standard errors of estimate (SE) further when added to this list. Organic C content (OC) alone predicts the bulk densities (DB) of upland soils with a SE of 0.19 g cm−3 (r2 = 0.462): DB = 1.66 − 0.308 · OC0.5.
Metal Binding Properties of Leaf Litter Extracts: I. Discontinuous Spectrophotometric Titration with Iron and Copper
Authors: Blaser P. , Flühler H. , Polomski Janina
Published: July 2010

A spectrophotometric titration method is proposed with which the maximum Fe or Cu binding ability of leaf litter extracts and the conditional stability constants of the organo‐metallic compounds can be determined. The method was checked against the dialysis method of Zunino and Martin (1977) using Cu as titrant. With Fe instead of Cu the spectrophotometric titration yields also plausible results. In the latter case, however, the results cannot be verified with dialysis experiments because of the colloidal nature of aqueous Fe(OH)3.

The distribution between bound and free metal ions can be described by rectangular hyperbolas (Langmuir type regression models). The measurements deviate systematically from the simple Langmuir equation. These deviations can be adequately described if the heterogeneous mixture of dissolved organic constitutents is considered as a system of two independent components with distinct distribution isotherms. The errors involved in the estimation of the conditional stability constants and of the maximum binding abilities are analyzed.
Mineralogy of a Chronosequence Formed in New River Alluvium
Authors: Harris W. G. , Iyengar S. S. , Zelazny L. W. , Parker J. C. , Lietzke D. A. , Edmonds W. J.
Published: July 2010

The mineralogy of four soils (T0, T1, T2, T3), formed in progressively older New River alluvium, was studied with the assumption that trends could be attributed to age differences. Particle size was determined by pipette; free Fe by citrate‐dithionite (CD) extraction; sand mineralogy by petrographic techniques, heavy liquid separation, and X‐ray diffraction (XRD); and silt and clay mineralogy by XRD and thermal analysis. Clay illuviation and percent CD‐Fe increase with age. An increase in CD‐Fe with depth suggests Fe illuviation. Quartz, feldspar, mica, and amphibole are the major sand‐sized minerals in T0 and T1, with slightly less amphibole in T1. Predominance of quartz and resistant heavy minerals in T2 and T3 suggests a wide time gap between T1 and T2. Trends in silt mineralogy parallel those of sand. Clay mineralogical data show an age progression from mica and vermiculite to hydroxy interlayered vermiculite to kaolinite. Kaolinite appears to form very slowly from other layer silicates, but whole‐soil trends suggest that it may form more rapidly from sand and silt‐sized feldspar. With time, hydroxy interlayered vermiculite becomes the dominant clay‐sized mineral in Ap horizons while kaolinite and vermiculite increase with depth. The depth trend for kaolinite is attributed to eluviation and slow replenishment in the surface, and for the other minerals to decreasing weathering intensity with depth. Whole‐soil data reflect illuviation and reveal a concentration of quartz in the surface with time. Comparison of mineralogical trends suggests that stability is reached sooner in coarser than in finer size fractions.
Polycomponent Interstratified Phyllosilicates in Dolomite Residuum and Sandy Till of Central Wisconsin
Authors: Lim C. H. , Jackson M. L.
Published: July 2010

Clay minerals of four central Wisconsin soil parent materials containing highly interstratified layer silicates were difficult to identify in conventional Mg‐glycerol X‐ray diffraction (XRD) patterns. One group was from dolomite residuum (65% clay); another from sandy till (6% clay, with only small resolved XRD peaks). The Mg‐saturated, glycerol‐solvated clays of the former gave X‐ray diffractograms with diffuse and continuous low‐angle scatter ending with a dropoff at the (001) spacing of 7Å. Potassium saturation and heating at 400°C yielded an intense, sharp 10Å peak, identifying coincidence of XRD peaks for mica + vermiculite + smectite. Shoulders extending from the sharpened 10Å peak to the 7Å peak and toward low‐angle spacings indicated the presence of chlorite. Incomplete collapse of interlayers at 550°C and the production of a 14.2Å peak following fusion in LiNO3 at 300°C confirmed the presence of chlorite. Discrete kaolinite occurring in association with other phyllosilicates was revealed by the 11.2Å peak after Li saturation and DMSO intercalation. The X‐ray diffractograms indicated short‐range order in irregularly interstratified phyllosilicates occurring in ternary (3‐component), quaternary (4‐component), and quinary (5‐component) mixtures. The quantitative mineralogy, as assessed by K content, cation exchange capacity (CEC), selective dissolution, and thermal methods, averaged 15% mica, 10% vermiculite, 25% montmorillonite, 5% chlorite, and 30% kaolinite.
Response of the Cu2+ and Cd2+ Ion‐Selective Electrodes to Solutions of Different Ionic Strength and Ion Composition
Authors: Cavallaro N. , McBride M. B.
Published: July 2010

The Cu2+ and Cd2+ specific ion electrodes are shown to closely reflect calculated activities of Cu2+ and Cd2+ in solution with variable amounts of Cl‐ and a wide range of ionic strengths. Published stability constants for the chloride complexes of Cd2+ are consistent with the electrode readings, while those given for Cu2+ appear to underestimate the stability of the CuCl+ species. The Al3+ ion interferes with electrode measurement of Cu2+ and Cd3+, creating a problem for the use of electrodes in some acid soils.
Statistical Analysis of Results from Irrigation Experiments Using the Line‐Source Sprinkler System
Authors: Hanks R. J. , Sisson D. V. , Hurst R. L. , Hubbard K. G.
Published: July 2010

The line‐source irrigation system has been used in many studies to determine the influence of several treatment variables and irrigation on yield and other traits. It has the advantage of using a minimum of space and shows visually the irrigation effects for some traits. Valid statistical tests for treatment effects and the treatment by irrigation interaction are possible if the treatments are replicated and randomized in strips at right angles to the sprinkler line. No statistical test is available for the effect of irrigation level on yield because irrigation amount is always applied systematically with no randomization. Since the irrigation effects are usually large and obvious there is no need to assign a probability level to their significance. However, caution should be exercised in the interpretation of small differences between adjacent irrigation levels and for potential bias in the estimates of the regressions of yield on irrigation level brought about by the systematic arrangement.
The Terra Rossa Limestone Contact Phenomena in Karst, Southern Indiana
Authors: Olson C. G. , Ruhe R. V. , Mausbach M. J.
Published: July 2010

A prevalent view is that the red clayey parent material (terra rossa) of Crider and associated soils is a residual product from solution of limestone in the karst of southern Indiana. The sharp, abrupt contact between terra rossa and limestone provides no evidence to support the concept of a residual origin from limestone solution. In addition, insufficient quantities of insoluble residue in the rock require dissolution of thickness greater than the limestone available. Elemental oxides common in the clay are many magnitudes greater than in the rock and vice versa. Clay minerals in the red clay differ in kind and amount from those of the rock. The <2µm size fraction is many magnitudes greater in the red clay than in the rock. Soil‐geomorphic studies indicate that the terra rossa is mainly debris derived from erosion of higher lying clastic sedmentary rocks and transport and deposition of that debris (pedisediment) on pediments cut into lower lying limestones. The pedisediment subsequently weathers to terra rossa. Therefore the premise is rejected that terra rossa is a residual product from the solution of limestone.
Simple Method for Predicting Drainage from Field Plots
Authors: Sisson J. B. , Ferguson A. H. , van Genuchten M. Th.
Published: July 2010

When the one‐dimensional moisture flow equation is simplified by applying the unit gradient approximation, a first‐order partial differential equation results. The first‐order equation is hyperbolic and easily solved by the method of P. D. Lax. Three published K(θ) relationships were used to generate three analytical solutions for the drainage phase following infiltration. All three solutions produced straight lines or nearly straight lines when log of total water above a depth was plotted versus log of time. Several suggestions for obtaining the required parameters are presented and two example problems are included to demonstrate the accuracy and applicability of the method.
Kinetics of Potassium Desorption in Soil using Miscible Displacement
Authors: Sparks D. L. , Zelazny L. W. , Martens D. C.
Published: July 2010

Kinetics of K desorption were conducted on samples from the Ap, A2, B21t, and B22t horizons of two Dothan (Plinthic Paleudults) soils. Aluminum‐ and calcium‐ saturated samples were equilibrated with K for 96 hours and then continuously leached with 0.01M CaCl2 until K was not detected in the leachate. The rate of K desorption from all samples increased rapidly initially and levelled off with time. Desorption was nearly complete in approximately 3 to 4 hours for the Ap, A2, and B21t horizons, and in 8 to 9 hours for the B22t horizons. Approximately 95–98% of the adsorbed K was subsequently desorbed suggesting K adsorption‐desorption in the Dothan soils was reversible. A linear relationship between time½ and percent K desorption indicated that diffusion was the predominant mechanism of K desorption in these soils. Diffusion‐controlled exchange would be expected due to the vermiculitic clay minerals present in the soils.

Potassium desorption conformed to first‐order kinetics. Apparent desorption rate coefficients (k′d) ranged from 0.3 to 1.3 hour−1. The magnitude of the k′d values decreased as clay content increased in the soils. This was ascribed to increased intraparticle transport and to increased diffusion in the more clayey samples. The k′d values were generally higher in the Al‐than in the Ca‐ saturated samples. The effect of flow velocity on rate of K desorption was investigated using velocities of 0.5, 1.0, and 1.5 ml min−1. The rate of K desorption increased only slightly with flow velocity.
Soil Shrinkage Relationships of Texas Vertisols: I. Small Cores
Authors: Yule D. F. , Ritchie J. T.
Published: July 2010

Soil shrinkage‐water content relationships are needed to describe pore size distribution, bulk density function, and potential vertical movement of Vertisols.

Ten‐centimeter long, 10‐cm diam cores were collected from the 10‐ to 20‐, 40‐ to 50‐, 70‐ to 80‐, 100‐ to 110‐, and 130‐ to 140‐cm depths of eight central Texas Vertisols. Four sites were adjacent mound and depression samples from two gilgai complexes. Profile description and analytical characterization were obtained for each site. Soil shrinkage was measured vertically and horizontally during a drying cycle from field water content to oven‐dry. Some field matric potential profiles were obtained at sampling.

The shrinkage curves are described in terms of structural, shrinkage, and residual water loss phases. All cores had normal, equidimensional shrinkage. Only sites sampled at matric potentials > −300 cm of water had structural water loss. The intersection between the structural and shrinkage phases (the swelling limit) was generally sharply defined when present and occurred at about −0.3 bar. Structural water loss increased with depth due to increasing matric potential, and the soil air content at the swelling limit was about 0.05 cm3/cm3. The water content at the swelling limit was related to the cation exchange capacity (CEC) and the −0.3 bar water content. The shrinkage limit was relatively constant (0.09–0.11 g/g) for seven of the sites, and all residual water loss occurred at < −15 bars. The total vertical shrinkage and the normal water loss were related to the CEC and to the coefficient of linear extensibility (COLE).
Deficit, High‐frequency Irrigation of Sugarbeets with the Line Source Technique
Authors: Miller D. E. , Hang An N.
Published: July 2010

Studies were conducted on sandy and loam soils to determine the effect of deficit, daily sprinkler irrigation on sugar production from sugarbeets (Beta vulgaris L.) using the line source technique. With a loam soil near the upper limit of available water at the start of the irrigation season, daily sprinkler irrigation rates of sugarbeets were reduced to 35 to 50% of estimated evapotranspiration (ET) rates without reducing sugar yields. On a sandy soil, sugar yields increased with irrigation rates up to 100% estimated ET, the maximum rate applied.
Dependence of Dioscorea Tuber Growth Rate on Water Content of an Andept Soil
Authors: Dawson Ray F. , Shrum Jeffrey E. , Mohammed Robert A.
Published: July 2010

Unexpectedly low tuber yields of a pharmaceutical crop (Dioscorea species) on an Andept soil in Central America led to a study of soil‐related limitations. Readily available water (0 to −20 cbar) controlled tuber growth rates to a far greater extent than other environmental factors. Relative tuber growth rates of seedlings increased linearly as soil water content increased from 0.14 to 0.45 cm3 cm−3. Growth increases occurred with water contents above field capacity provided that soil porosity was not reduced by compaction. Most efficient tuber dry solids accumulation occured at the mid‐range of soil water contents employed and amounted to about 2.0g liter −1 of water consumed by the plant. Total plant (tuber, vine, and roots) water use efficiency was 6.2 g liter −1 at the same soil water content.

Water use efficiency in general was related to soil water content in a bifunctional manner, whereas stomatal activity as measured by leaf diffusive resistance increased continuously with increase in soil water content. Thus, highest rates of deposition of photosynthate in the tubers were accomplished by highest but least efficient rates of water consumption.

The results indicate that low bulk density, free‐draining Andept soils limit Dioscorea tuber growth rate by an inability to deliver without interruption the required volumes of lowtension water.
Nutrient Changes in Decomposing Loblolly Pine Forest Floor
Authors: Jorgensen J. R. , Wells C. G. , Metz L. J.
Published: July 2010

In two loblolly pine stands (Pinus taeda L.), 11 and 32 years of age at study inception, nutrients in litterfall and throughfall were measured, and declines in nutrient content were observed as forest floor layers decomposed for up to 8 years. The forest floors up to 8 years of age in the two stands had similar rates of nutrient release. After 8 years of decomposition, 67% of the C, 27% of the N, 63% of the P, 91% of the K, 67% of the Ca, 79% of the Mg were released from the forest floor materials. In the younger stand, release from the forest floor accounted for 34, 59, 47, and 65%, respectively, of the N, P, K, Ca, and Mg assimilated annually into the aboveground biomass. In the older stand, the forest floor release accounted for 86, 104, 73, 72, and 71%, respectively, of the N, P, K, Ca, and Mg, indicating that as the stand matures, the importance of the forest floor increases in the nutrient cycling process. Nitrogen content of the forest floor appeared to increase through the third year of decomposition and then to decrease when needles and branches were assumed to be the only forest floor inputs. However, when fine particles and throughfall were included as forest floor inputs, no increase in forest floor N was observed.
A Finite Element Calculation for Determining Thermal Conductivity
Authors: Riha Susan J. , McInnes K. J. , Childs S. W. , Campbell G. S.
Published: July 2010

A new simple method for in situ measurement of thermal conductivity of porous materials was developed. A heated or cooled Al or glass probe was placed in soil, and its temperature was monitored over time. Thermal conductivity was determined using a finite element method to solve the radial heat flow equation for the temperature of the heated or cooled probe. The probe temperature, as a function of time, was modeled, and model thermal conductivity was adjusted until predicted probe temperatures agreed with measured values. Conductivities for sand, silt loam, and forest litter were measured over a range of water contents. Values obtained using a glass probe were not significantly different from those obtained using an Al probe. Conductivities were in good agreement with those obtained using a water bath method or computed from the deVries equation. There were significant differences between values obtained with heated and cooled probes in sand at intermediate water content.
Soil Distribution and Soybean Plant Accumulation of Manganese in Manganese‐Deficient and Manganese‐Fertilized Field Plots
Authors: Wilson D. O. , Boswell F. C. , Ohki K. , Parker M. B. , Shuman L. M.
Published: July 2010

Manganese (Mn) additions are required on certain southern Coastal Plain soils for maximum yield of soybeans (Glycine max (L.) Merr.). This study was conducted to determine the soil profile distribution of added Mn, the accumulation of Mn in soybean plant tops, and the production of plant dry matter in field plots having five rates of Mn and two soil‐pH levels. ‘Ransom’ soybeans were grown on an Olustee‐Leefield sand, an Ultic, Haplaquod‐Arenic, Plinthaquic Paleudult, adjusted to pH levels of 6.3 and 7.0 and supplied with Mn at 0, 5.6, 11, 22, and 56 kg/ha each year for three years. Near the end of the growing season in the first and third years, dry matter production and plant accumulation of Mn were determined on whole plants (R6 growth stage). At the end of the third year, extractable (DTPA and double‐acid) soil Mn was determined in 15‐cm increments to a depth of 90 cm.

Considering all Mn rates and pH levels, < 0.5% of the added Mn could be accounted for in the plant tops. Soil depth samples showed that most of the added Mn remained in the upper 30 cm of soil, even though at the high Mn rate, a total of 168‐kg Mn/ha had been applied. Summation of the Mn contents of all soil depth increments revealed that double acid extracted 32 to 57% and DTPA 2.6 to 7.2% of the total amount of applied Mn. Total dry matter production was reduced at the 0‐ and 5.6‐kg Mn/ha rates at the high pH level compared to the 56‐kg Mn/ha rate. Maximum dry matter production was obtained on treatments producing plants containing as little as 59‐g Mn/ha. Correlations between plant top Mn content (g/ha) and extractable‐soil Mn (kg/ha) in various depth increments gave r‐values significant at the 1% level for both extractants. DTPA‐extractable Mn accounted for 72%, however, but double acid only 22% of the variation in plant top Mn, considering all Mn rates over both pH levels.

Nearly all of the broadcast Mn applied to this very sandy soil remained in the rooting zone. Only a small fraction was accumulated into the tops of soybean plants, despite the fact that, in some treatments, the plants were under Mn‐deficiency stress. These results emphasize the inefficient utilization of broadcast Mn by soybean plants and suggest that other methods of application, such as foliar or band, should result in more efficient use of applied Mn.