bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantitative Evaluation of the Strong‐Force Model for Expansion and Contraction of Vermiculite
Authors: Kittrick J. A.
Published: July 2010

The model used considers expanding forces arising from hydration of positive interlayer ions, negative charge sites, and vermiculite surface. Opposing the hydration forces is the electrostatic contracting force between positive interlayer ions and negative charge sites.

The contribution of each force to net thermodynamic values is considered independently of other forces. Hydration of interlayer cations may then be estimated from values for bulk solution. Hydration of the negative charge sites is estimated from the entropy change during interlayer water sorption by Na vermiculite. Hydration of the vermiculite surface is estimated from the enthalpy change for wetting of an oxygen‐silicate surface. The contribution of the electrostatic contracting force is estimated from the lattice enthalpy of an ionic structure containing the interlayer cation and an anion equivalent to the negative charge site.

The thermodynamic estimates based upon the model are in qualitative agreement with water sorption by Li, Na, K, Rb, and Cs vermiculites and are in quantitative agreement with Na vermiculite. These are the only comparisons with the experiment possible at present. Agreement was dependent upon strong hydration of negative charge sites.

The model and the thermodynamic estimates suggest a mechanism for fixation of ions by vermiculite. The hydrating and electrostatic forces appear to be rather closely balanced, resulting in a relatively small enthalpy change favoring water sorption. This permits the entropy contribution from interlayer water molecules, which favors desorption of water, to drive the vermiculite system to spontaneous contraction, fixing interlayer ions such as K+.
Experimental Study of the Influence of the Partial Pressure of Carbon Dioxide on the pH Values of Aqueous Carbonate Systems
Authors: Ponnamperuma F. N. , Castro Ruby U. , Valencia Carmen M.
Published: July 2010

The pH values of 0.001N and 0.01N solutions of sodium carbonate and of aqueous suspensions of CaCO3, MnCO3, and FeCO3 equilibrated at 25C with CO2‐N2 mixtures containing 1–100% CO2 conformed to the equations, pH = 7.85 + log Na+ − log Pco2 + log γhco3‐ and pH = K − ⅔ log Pco2 + ⅓ log γhco3‐ − ⅓ log γm2+, respectively. Suspensions of sodic and calcareous soils, equilibrated similarly, behaved like the corresponding simple systems, while reduced soils high in active iron yielded a pH‐log Pco2 relationship almost identical with that obtained experimentally with an aqueous suspension of Fe3(OH)8.
Soil Scientists' Proficiency in Describing Soil Consistence
Authors: Nettleton W. D. , Holzhey C. S. , Flach K. W. , Brasher B. R.
Published: July 2010

A recent field trip for a group of soil scientists from the western United States permitted comparison of professional soil scientists' description of dry and moist soil consistence and comparison of the descriptions of consistence with unconfined compressive strengths of dry soil.

Field party members agreed fairly well with each other in the description of the consistence of moist soils (60% agreement) and dry soils (70% agreement). There was a logarithmic relation between their description of dry consistence and unconfined compressive strengths. The unconfined compression test thus seems to provide a suitable soil consistence standard. The range in unconfined compressive strengths within classes increases from the slightly hard to the very hard classes.
Fractionation of Phosphorus in Lake Sediments: Analytical Evaluation
Authors: Frink C. R.
Published: July 2010

Methods for the fractionation of P in soils were evaluated in the fractionation of P in lake sediments. Both Al‐P and Fe‐P may be determined readily and precisely by the Chang and Jackson procedure. Reductant‐soluble P was more difficult: modifications of a citrate oxidation procedure utilizing KMnO4 produced an acceptable method. Large amounts of Fe in the Ca‐P extracts caused low results, but this was overcome by limiting the aliquot size. Organic P determined by difference between total and inorganic P was not related to the organic matter content of the sediments. An alternative measure of inorganic P, obtained by summing the inorganic P fractions, yielded values for organic P which were correlated with organic matter.
Effect of Chloride Salts on Ammonium Nitrogen Release in Two Hawaiian Soils
Authors: Singh B. R. , Agarwal A. S. , Kanehiro Y.
Published: July 2010

Akaka silty clay and Wahiawa silty clay were treated with the chloride salts of mono‐, di‐, and trivalent cations. Carbon dioxide production in salt‐treated samples was slightly less than in the control. NH4‐N release was a direct function of salt concentration and length of incubation. Once the NH43 ions were formed from soil organic‐inorganic complexes, the different cations had a second and larger effect on the exchange reaction which transferred the NH4 ions from surface sites to the soil solution. The equilibrium state of the exchange reaction was largely dependent on the nature and concentration of cations in the soil solution, as well as on the length of incubation.

A consideration of the overall effect of cations on NH4 release in the two soils led to the series, Al > Fe > Ca > Mg > K > Na, in order of decreasing NH4 replacing power. However, the series was applicable only to a concentration of 0.1M. At higher concentrations, Al and Fe ions were believed to be complexed in the soil and were thereby inactivated. The added salts had little or no effect on NO3‐N content of the two soils.
Effect of N, P, and K Fertilization on the Mineral Composition of Tobacco
Authors: Peterson L. A. , Dolar S. G. , Chesters G.
Published: July 2010

The effect of N, P, and K fertilization on the mineral composition of tobacco leaves (Nicotiana tabacum L.) was evaluated under field conditions for three cropping seasons. The amounts of added N, P, and K had a highly significant effect on the leaf concentrations of Ca, Mg, B, Zn, Cu, Mn, and Al and a significant effect on Fe concentration. Correlations between the concentrations of N, P, and K in the leaves and concentrations of the other mineral components of the leaf were similar to those for added N, P, and K.

Nitrogen had a direct effect on Mg and Mn and an inverse effect on B concentrations in the tobacco leaves. Phosphorus had a direct effect on Ca, Mg, and B and an inverse effect on Zn and Cu. Potassium had an inverse effect on Ca, Mg, B, Zn, and Cu. Although not all coefficients were significant, K was inversely correlated to all eight mineral elements.
Influence of Silicie Acid on Uptake of Mn, Al, Zn, and Cu by Tomatoes (Lycopersicum esculentum) Grown on an Acid Soil
Authors: Peaslee D. E. , Frink C. R.
Published: July 2010

Treatment of an acid Merrimac fine sandy loam with H2SiO3 significantly decreased the concentration and total uptake of Mn and Al in tissues of greenhouse grown tomatoes (Lycopersicum esculentum) but affected neither the uptake nor tissue concentrations of Cu or Zn. Yields of dry matter were not significantly increased by Na2CO3 treatments. Increases in yield of dry matter were more closely associated with decreased concentrations of Zn and Cu and less closely associated with decreased concentrations of Al and Mn.
Regional Distribution of Potassium in the B Horizon Clay of Some Prairie Loess Soils of the Midwest
Authors: Wells K. L. , Riecken F. F.
Published: July 2010

To test the hypothesis that K content of Iowa soils was related to soil development, samples from the B horizon of selected sites were obtained from loess‐derived prairie soils at several locations within the state. Samples were also obtained from Nebraska and Illinois loess soils to relate the Iowa study to the midwestern prairie region. Total K in clay from the B horizons decreased progressively from west to east. This was explained on the basis of concurrent increase in average annual precipitation from west to east across the area. No consistent relationships between total K content and standard indexes of profile development were obtained. However, K was highly correlated with depth to the B horizon. Although montmorillonite was the dominant clay mineral in all samples, there was relatively more illite in samples of higher K content and from sites receiving lesser amounts of annual precipitation. Studies of K released to sodium tetraphenyl boron (NaTPB) on Iowa soils reflect the trends in total K content found in the B horizons.
Entrapped Soil Air in a Field Site
Authors: Garner Dale E. , Donaldson John K. , Taylor George S.
Published: July 2010

Soil air was entrapped at 50–100 cm of water pressure in a wooded field site due to infiltrating water. The air was expelled through piezometer tubes for 2 or 3 months following spring rainfall. Seven additional sites did not exhibit this phenomenon, which appears to be caused by a favorable combination of soil and vegetative factors.
Bentonite Stabilization of Soil to Resist Wind Erosion
Authors: Hsieh J. J. C. , Wildung R. E.
Published: July 2010

Preliminary investigations indicate that the addition of bentonite to soil followed by moistening will significantly reduce the susceptibility of the soil to wind erosion after drying. This effect persists after rupture of the aggregates originally formed through bentonite amendment provided the soil is remoistened.
The EMF of Platinum Electrodes in Dilute Solutions and its Relation to Soil pH
Authors: Bohn H. L.
Published: July 2010

An equation is derived for mixed potentials of electrodes which explains their non‐Nernstian behavior in dilute solutions and at nonequilibrium conditions. Adding iron(II) sulfate to soil suspensions resulted in EPt/pH slopes which were unrelated to the reaction taking place because EPt is a mixed potential and because the pH is governed to a significant extent by non‐redox reactions.
Gaseous Products Produced by Anaerobic Reaction of Sodium Nitrite with Oxime Compounds and Oximes Synthesized from Organic Matter
Authors: Porter Lynn K.
Published: July 2010

Hydroxylamine was reacted with a number of soil organic matter sources to produce organic matter oximes. This reaction has been used to measure the carbonyl groups in organic matter. The soil organic matter, organic matter oximes, oxime compounds, and aromatic compounds were reacted with buffered (pH 5.0 and pH 6.0) NaNO2 solutions in evacuated Rittenberg tubes. The gaseous products resulting from these nitrate reactions were analyzed by gas chromatography and compared to determine the nature of soil organic matter oximes and to determine if such oximes could be a source of N2O production in soils. All oxime compounds studied, except dimethylglyoxime and the quinone oximes, which produced NO, formed N2O as their major gaseous products. The major gaseous product from organic matter oximes, organic matter, and aromatic compounds was NO. The results suggest that if the reaction product of NH2OH and organic matter is an oxime, the oxime resembles or reacts like quinone oximes or dimethyl‐glyoximes. The negligible amounts of N2O produced from the reaction of NaNO2 with organic matter oximes suggests that this is probably not a pathway for N2O loss from soils.
Observations on Opal Phytoliths in a Soil Biosequence in Southeastern Minnesota
Authors: Verma Shive D. , Rust R. H.
Published: July 2010

The content of opal phytoliths was measured in selected horizons of six soils from Goodhue County, Minn. The highest amount of opal phytoliths occurred in a Typic Hapludoll (Kenyon series) suggesting a soil developed under dominant grass vegetation because most of the opal is derived from big bluestem (Andropogon gerardi L.) and little bluestem (A. scoparius L.). Opal phytoliths isolated from some horizons were similar in morphology to reference slides made of opal from burr oak (Quercus macrocarpa Michx.), ironwood (Ostrya virginiana (Mill.) K. Koch), and a shrub, hazel (Corylus americana Walt.).

Opal phytoliths in two associated Aquollic Hapludalfs (Kasson and Taopi series) were derived primarily from big and little bluestem and with minor amounts from trees. This suggested at least a period of forest vegetation. A striking feature of Kasson, Kenyon, and Taopi soils is the higher content of opal phytoliths in till material II which begins in the B2 horizon at depths of about 50 inches. Possibly at one time the top of material II might have been prairie covered landscape and the overlying silty material was deposited later.
Infiltration and Water Depletion in Lysimeters
Authors: Qashu Hasan K.
Published: July 2010

Evapotranspiration losses from five lysimeters with different plant species were estimated. Prediction equations were developed and used to estimate soil water regimens, infiltration and runoff in lysimeters with vegetative cover. Calculated soil water contents and runoff for lysimeters with five different plant species were good estimates of measured quantities.
Comparison of Computed and Measured Moisture Redistribution Following Infiltration
Authors: Staple W. J.
Published: July 2010

Redistribution of water was measured in three soils following two different initial amounts of infiltration. The measured redistribution profiles were compared with those computed from the flow equation taking into account hysteresis in the drying tension vs water content relationship. Agreement between measured and computed moisture profiles was considered satisfactory. A procedure was outlined for determining wetting diffusivities and conductivities in the wetting front on the basis of soil moisture profiles obtained during redistribution. The different shapes of the drying scanning tension curves provided some insight into the differences in particle size distribution that influence the water‐holding capacity of soils.
Effect of Chelating Agents on the Availability to Plants of Carrier‐Free 59Fe and 65Zn Added to Soils to Simulate Contamination From Fallout
Authors: Wallace A. , Mueller R. T.
Published: July 2010

Carrier‐free 59Fe and 65Zn were added to Dinuba fine sandy loam (neutral), Hacienda loam (calcareous), and Yolo loam (slightly acid), and equilibrated through drying and wetting cycles. Bush bean (Phaseolus vulgaris L., var. ‘Improved Tendergreen’), corn (Zea mays L., var. ‘Golden Cross Bantam’), and soybean (Glycine max Merr., var. ‘PI‐54619‐5‐1’ and ‘Hawkeye’) were grown in 59Fe‐containing soil and bush bean (P. vulgaris L.), corn (Z. mays L.) and cotton (Gossypium hirsutum L., var. ‘Acala 442’) were grown in 65Zn‐containing soil. One‐half of those with 59Fe received Na2EDDHA equivalent to 4.4 kg of Fe/ha had there been a 1:1 metal chelate and one‐half of those with 65Zn received Na2EDTA equivalent to 5.5 kg of Zn/ha had metal been added with the chelating agent. The chelating agents had many different effects depending on soil and on crop. Chelating agents increased the specific activity of 59Fe in the bush bean and soybeans. The specific activity of 59Fe in corn was unchanged by chelating agent but was much higher than in bush bean and soybean with or without chelating agents. When carrier Fe was added, the behavior of 59Fe was essentially unchanged. The specific activity of 65Zn in plants in most cases was increased by the EDTA. The EDTA increased both 65Zn and total Zn in corn, but the specific activity generally was unchanged by the chelate.
Cotton Growth in an Acid Fragipan Subsoil: I. Effects of Physical Soil Properties, Liming, and Fertilization on Root Penetration
Authors: Soileau J. M. , Engelstad O. P.
Published: July 2010

Roots of established cotton (Gossypium hirsutum, var. ‘Rex’) seedlings were allowed to grow into undisturbed or laboratory‐prepared cores of an infertile, highly acid, compact fragipan subsoil (Dickson series). A significant positive correlation was found between the number of roots in the subsoil cores and soil moisture. Examination of thin sections revealed a low total porosity and a predominance of small, discontinous planar voids in Dickson fragipan, which apparently contributes to the narrow range of available water in this horizon. The number and dry weight of roots decreased with increase in bulk density; however, the 1.5 g/cm3 bulk density of the fragipan is not considered an important factor for cotton root penetration in this subsoil. Root growth was not consistently related to soil strength as measured with a penetrometer probe. Significantly greater root dry weights and depth of penetration were found in limed than in nonlimed cores, regardless of bulk density, soil strength, or NPK fertilization. Results of this study indicate that adverse chemical or physiological effects related to extreme soil acidity may be dominant over other physical and chemical factors that inhibit root growth in Dickson fragipan subsoil.
Inhibition of Nitrification as a Deterrent to Nitrogen Loss
Authors: Huber D. M. , Murray G. A. , Crane J. M.
Published: July 2010

Inhibition of nitrification of fall‐applied ammonium sulfate with “N‐Serve”3 prevented movement of applied nitrogen below the 30.5‐cm depth. Yield of wheat (Triticum aestivum L., Cultivar Gaines) fertilized with ammonium sulfate and N‐Serve was increased 37 to 42% compared to no increase in yield with the nitrate form.
Alkaline Permanganate Oxidation of Methylated and Unmethylated Fulvic Acid
Authors: Schnitzer M. , Desjardins J. G.
Published: July 2010

The alkaline permanganate oxidation of humic and fulvic acids yields small amounts of benzene polycarboxylic acids that range from the di‐ to the hexa‐form. Low yields may be due to the presence of electron‐donating substituents, such as OH groups, on aromatic rings. To make the rings less susceptible to destruction by alkaline KMnO4, we attempted to reduce the electron‐donating effect by converting OH groups via methylation to OCH3 groups. The alkaline permanganate oxidation of methylated FA, however, yielded the same types and similar amounts of benzene carboxylic acids as that of the untreated FA. Failure of methylation to increase the variety and yield of oxidation products may be due to inability to either methylate all (phenolic) OH groups or, more likely, to reduce electron‐donating effects sufficiently.
Hydrolysis and Uptake of Pyrophosphate by Plant Roots
Authors: Gilliam J. W.
Published: July 2010

Pyro‐ and orthophosphate solutions were equally effective in supplying P to P‐deficient wheat (Triticum vulgare), corn (Zea mays L.), and barley (Hordeum vulgare L.). P‐deficient roots absorbed the pyrophosphate ion per se and also rapidly hydrolyzed the pyrophosphate as indicated by 40–55% of the P being present as the ortho form after 24 hours. It was concluded that this hydrolysis was caused by phosphatase present on external portions of the roots. Wheat roots which were P‐ deficient had approximately 1.6 times as much phosphatase activity as non‐deficient roots (per unit weight) as determined by appearance of orthophosphate. Evidence indicated that P‐ deficient wheat roots exposed only to orthophosphate produced significant quantities of pyrophosphate.
Soil Water Evaporation, Isothermal Diffusion, and Heat and Water Transfer
Authors: Fritton D. D. , Kirkham Don , Shaw R. H.
Published: July 2010

Temperature and water distribution data were taken for a 9‐ by 11‐ by 20‐cm soil column where wind was the evaporation agent and for a similar soil column where radiation was the evaporation agent. A Webster silty clay loam soil characterized by a soil‐water retention curve and an inflow diffusivity versus water content curve was used in the experiments. The experimental results were compared with results calculated from a solution of the diffusion equation normally used to describe isothermal movement of soil water and from a heat and mass transfer solution which accounted for temperature effects. It was found that the isothermal diffusion equation would describe the cumulative evaporation for the wind and for the radiation treatments. The isothermal diffusion equation did not predict the formation of a surface layer of dry soil, and thus, did not describe the water distributions for the radiation treatment for times greater than 20 hours or for the wind treatment for times greater than 200 hours. A heat and mass transfer equation did predict the development of a dry surface layer and did describe the water distribution where temperature gradients were important.
Effects of Saline Water on the Chemical Properties of Some Tropical Soils
Authors: El‐Swaify S. A. , Swindale L. D.
Published: July 2010

Surface and subsurface samples of soils representing the Tropical Red Earths and Tropical Red Deserts were equilibrated with unbuffered salt solutions which had the composition of sea water and ranged in concentration between 0.61N and 0.0061N. The effects of these treatments on soil pH, the concentration of soil solution, and exchangeable sodium percentages were subsequently characterized. The original acidities of these soils were highly resistant to change. Neither soil showed a tendency to accumulate salts by extraction from percolating solutions. Studies of exchangeable sodium percentages at the various concentration levels supported the valance‐dilution principle. At high salt concentrations, however, the observed affinities of these soils for divalent cations were higher than those predicted by the commonly used US Salinity Laboratory regression equation.

To eliminate the possible interference by CaCO3 in observed ionic equilibria, Na‐Ca exchange studies were conducted on carbonate‐free soil samples. Isoconcentration isotherms were constructed at electrolyte concentrations of 0.01, 0.1, and 1.0N, compared with isotherms calculated from the US Salinity Laboratory's regression equation. Large discrepancies were observed at 1.0N concentration, particularly for the lowest soil horizons. For that concentration, it was found that predictions of ionic distribution based on the theory of the diffuse double layer can closely describe Na‐Ca equilibrium when large values of surface charge densities are assumed.
Nitrate Transformations in a Column with a Controlled Water Table
Authors: Meek B. D. , Grass L. B. , Willardson L. S. , MacKenzie A. J.
Published: July 2010

The relation of dissolved oxygen, soluble carbon, and redox potential to the movement of nitrate in soil columns and into submerged tile lines was studied. Columns 300 cm long were drained at depths of 180, 240, or 300 cm with the water table in all columns maintained at 175 cm. After adding ammonium nitrate and irrigating, the peak in nitrate concentration moved downward to the 160‐cm depth, but nitrate concentrations decreased at 180 cm and almost disappeared at the 240‐ and 300‐cm depths. The soil solution at 180 cm contained an average of 5.2 ppm nitrate‐nitrogen and a maximum of 16 ppm. In contrast the soil solution at 240 or 300 cm, which had passed through a submerged zone of 65 or 125 cm, averaged 0.5 ppm and had a maximum concentration of 1.1 ppm. Disappearance of nitrate was associated with decreases in redox potential, oxygen content of the soil solution and oxygen levels in the soil atmosphere, and with increases in soluble iron and manganese. Denitrification occurred without submergence if the soil redox potential was sufficiently low. Results of this experiment indicate that nitrate concentrations probably can be reduced in tile effluents by submerging the tile lines.
Hillslope Sedimentation and Soil Formation in Northeastern Iowa
Authors: Kleiss Harold J.
Published: July 2010

Systematic investigation of a hillslope from summit to alluvial positions revealed that particle size variations within the soil A horizons are due to sedimentological sorting. The mean particle size in the surficial sediments follows a systematic decrease within two subset systems down the hillslope. Each subset is expressible mathematically. A discordance in the backslope position is caused by truncation of a sand zone within the till underlying the surficial material. Hillslope sedimentation has also influenced accumulation of organic matter, bulk density, and cation exchange capacities in the soils formed at various positions on the slope. Profile characteristics indicate little pedogenic development; rather, many of the soil properties are inherited from the sedimentary nature of the hillslope surficial sediment.
Bulk Density, Aggregate Stability, and Organic Matter Content as Influenced by Two Wheatland Soil Management Practices
Authors: Tanchandrphongs S. , Davidson J. M.
Published: July 2010

The amount of organic matter in the top 15.0–30.5 cm of a Grant silt loam after 11 years of stubble mulching was significantly greater than that in clean tilled (plow) plots on this soil over the same time period. Aggregation under stubble mulching was greater than with clean tillage. Soil compaction was noted by an increase in bulk density at the 23.0–30.5 cm depth in clean tilled plots, but was absent at all depths measured in stubble mulched plots.

Annual nitrogen applications gave a significant increase in organic matter content at the 15.0–23.0 cm soil depth. Stubble mulching in an alfalfa (Medicago sativa L.)‐wheat (Triticum aestivum L.) rotation program was shown to influence the soil physical properties more significantly than did stubble mulching in a continuous‐wheat or the clean tillage in an alfalfa‐wheat program.
Effects of Nitrogen and Phosphorus Fertilization on Juvenile Growth of Planted Yellow Poplar on an Eroded Old Field
Authors: Farmer R. E. , Snow E. A. , Curlin J. W.
Published: July 2010

In a yellow poplar (Liriodendron tulipfera L.) plantation, three levels of nitrogen (0, 336, 672 kg/ha) and phosphorus (0, 168, 336 kg/ha) fertilizer applied at planting were tested in factorially arranged experiment with a split plot design. Nitrogen fertilizer was applied in holes near trees by two methods: loose and in perforated plastic bags.

Survival after 5 years was 56% and was not influenced by treatment. Both nitrogen and phosphorus stimulated growth during the first 2 years after planting but phosphorus was effective only when combined with nitrogen fertilization. During this period, loose application of nitrogen fertilizer gave better results than bagged application. After 5 years, only nitrogen effects were statistically significant; mean height (2.59 m) of trees in the most effective nitrogen treatment (672 kg/ha) was 80% greater than controls.
Fertilizer Nitrogen and Crop Rotation in Relation to Movement of Nitrate Nitrogen Through Soil Profiles
Authors: Olsen R. J. , Hensler R. F. , Attoe O. J. , Witzel S. A. , Peterson L. A.
Published: July 2010

Recovery of fertilizer N by three successive corn (Zea mays L.) crops and as inorganic N in the soil profile following the last crop ranged from 72 to 88%. Total amount of NO3‐N in the soil profiles was directly related to the rate of N application and to the frequency of corn in the rotation. More leaching of NO3‐N generally occurred between fall and spring samplings than during the growing season. The most effective methods indicated for limiting the amounts of NO3‐N passing through the soil profile to the water table include: limiting rates of N fertilizer to approximately that required by the crop, reducing the acreage and frequency of corn or other crops that received fertilizer N in the rotation, and maintaining a crop cover on the land as much of the time as is feasible.
Chemical Differentiation of Selected Wisconsin Histosols
Authors: Isirimah N. O. , Keeney D. R. , Lee G. B.
Published: July 2010

Samples of 16 Wisconsin Histosols representing a wide range in botanical composition and in various stages of decomposition were used to evaluate selected chemical criteria which may be useful in classification of histic materials. Chemical parameters which related closely with the relative degree of humification were the organic matter cation exchange capacity, total N content of the organic matter, and C/N ratio. The forms of N soluble in 6N HCl varied widely, and no marked trends existed in the N distribution data with respect to the degree of decomposition of the samples.

The amounts of C and N extracted from the samples by NaDowex A‐1 chelating resin bore no relationship to their degree of decomposition. Hot water soluble C and N decreased with increasing degree of decomposition. The absorbance of 0.025M Na‐pyrophosphate extracts of the soils at 340 or 550 mµ was related highly to the amount of organic C in the extracts.

Samples were biologically degraded by incubating them under aerobic or waterlogged conditions for 1 year. On the average, Na‐resin and hot water extracted less and Na‐pyrophosphate more of the organic C from the incubated than from the original samples.

The results of this investigation indicate that Na‐pyrophosphate solubility is useful in characterizing histic materials and that this extraction procedure can be adapted readily to routine analysis of samples in the laboratory.
Soil Moisture Tension Transients Associated with Evapotranspiration from a Water Table
Authors: Bianchi W. C. , Tovey Rhys
Published: July 2010

Soil moisture tensions were recorded continuously in lysimeters containing a loam soil and a controlled water table. Seven strain gauge‐pressure transducer‐tensiometers were spaced from 20 to 110 cm above the 158‐cm water table. The velocity at which the morning and evening soil moisture tension minimum and maximum progressed downward through the root zone and capillary fringe proved inconsistent with soil moisture flow theory. This was interpreted as showing that even at low tensions a decrease in the moisture film continuity between the soil and tensiometer bulb relative to that between the few roots in contact with the bulb, caused the measurement to be biased toward the tensions associated with the root system. When the minimum daily tension exceeded 400 cm of H2O, soil‐bulb continuity was lost and, as a result, the characteristic wave form of daily evaporation (ET) demand was also lost. By placing the tensiometers in the capillary fringe where roots are absent, they could record the changing demands of ET on the capillary fringe. A method was tested for estimating water table uptake from a diffusivity based on the velocity of propagation of tension waves induced into the soil profile by daily ET and associated diurnal gradient changes.
Exhumed Paleosols and Associated Modern Till Soils in Western Illinois
Authors: Bushue L. J. , Fehrenbacher J. B. , Ray B. W.
Published: July 2010

Exhumed paleosols and modern soils formed in Illinoian and/or Kansan till occur in a complex pattern in many places on the sides of incised valleys in predominantly loess covered regions in western Illinois and adjacent states. The paleosols studied in western Illinois are thicker, finer textured, grayer and more poorly drained, and more impermeable than the modern soils formed during late Pleistocene and Recent weathering. However, the paleosols and modern soils do not differ greatly in chemical properties.

The presence of highly contrasting paleosols and modern till soils on the same slope not only cause problems in soil mapping, but because of side‐hill seepage, and the fine texture and poor physical condition of the paleosols, difficult problems in soil management also exist. The use of soil complexes, undifferentiated units, or the inclusion of strongly contrasting soils in given mapping units is necessary to show these soil conditions on many slopes.
Chemical Properties of a Forest Soil Affected by Fertilization and Submergence
Authors: McKee W. H.
Published: July 2010

In samples from the Al horizon of poorly drained flatwoods soils from the Gulf Coastal Plain (Typic glossaqualfs), a combination of lime and phosphorus abruptly increased soil pH after 6 days of laboratory submergence. Treatment with only one of these additives, with other conditions the same, did not influence pH. After submergence for 60 days, pH values were near neutral. Redox values were lowered about 500 mv by waterlogging; they were not altered by lime or phosphorus application.

Drying after submergence decreased pH, but effects of waterlogging remained. Submergence reduced levels of exchangeable Al, Ca, and Mg, probably by changing the acid strength of the soil, and shifted Al‐P to Fe‐P. Results of cyclic submergence indicate that effects are slowly reversible.
An Indirect Method for the Measurement of Sulfate by Barium Absorption Spectrophotometry
Authors: Borden F. Yates , McCormick Larry H.
Published: July 2010

A method was developed to analyze for aqueous‐solution sulfate by precipitation by barium and measuring the remaining barium by atomic absorption spectrophotometry. The method compared favorably with a turbidimetric and a gravimetric method. Sensitivity was 1.5 ppm S/1% absorption. The method could be used without dilutions for solutions containing up to 150 ppm S.
Cation Exchange Capacity and Component Variations of Soils of Southeastern USA
Authors: Fiskell John G. A.
Published: July 2010

Several methods for determining CEC were employed for soils selected from southeastern United States to provide a wide range in acidity, clay mineralogy, clay content, and organic matter content. Unbuffered saturation was made with 1N CaCl2, NaCl, NH4Cl, or KCl. Soluble salts were removed by rapid stirring and centrifuging of the soil samples after each of three water and ethanol replacements. Buffered systems were used to measure CEC at pH 4.8, 7.0, and 8.3. Sum of exchangeable bases was not equivalent to values for CEC by unbuffered salts. Increases in CEC from the latter values to those found at pH 7 or pH 8.3 were not identical with corresponding values for titratable soil acidity. Standard deviations of the methods were much lower than differences in CEC between methods. All soils showed less CEC with NH4+ or K+ saturation compared to Ca2+ or Na+ saturation; the difference was attributed chiefly to reaction with expanding phyllosilicates. For CEC measured at pH 7, component CEC of organic matter ranged from 40 to 180 between soil series, with the higher values associated with soils having free carbonate present. Under the same conditions, calculated CEC of clay ranged from 8 to 63 assumingnegligible CEC of the silt component. Apparent pH‐dependent CEC of these soils was mainly attributed to hydroxy‐Al associated with the organic matter and interlayering of expanding phyllosilicates.
Effect of the Separation of Nitrogen and Sulfur Sources on Sulfur Uptake by Corn
Authors: Rehm G. W. , Caldwell A. C.
Published: July 2010

The effect of fertilizer N and S sources on the absorption of S by corn (Zea mays L.) was studied in the greenhouse with the use of 35S. When the N and S sources were separated by a physical barrier, the NH4 ion, when compared to the NO3 ion, produced a significant increase in the S absorption from the fertilizer. The data indicate that the influence of the N source on S absorption is the result of physiological reactions or processes within the plant or the root tissue. The separation of the N and S sources had no significant effect on the total S and total N content of the tissue.
Effects of Stemflow Water on a Miami Soil Under a Beech Tree: II. Chemical Properties
Authors: Gersper P. L. , Holowaychuk N.
Published: July 2010

Effects of the stemflow component of the biohydrologic soil forming factor on chemical properties of a Miami soil were investigated. Chemical analyses were made on horizons from soil profiles sampled in radial trenches emanating from the stem of a large American beech tree, at four distances from the stem. Data were subjected to analysis of variance using a two‐way classification with four replications and means were tested with Duncan's Multiple Range Test.

A beech tree was selected for the study in order to maximize the intensity of the biohydrologic factor (because of the large amount of stemflow associated with this species). Stemflow water was collected periodically for volume measurements and chemical analyses.

Stemflow water from the beech tree had a very high content of organic C; moderately high quantities of Ca and K; small quantities of Na, Mg, and P; and very small quantities of Al, Fe, and Mn. Stemflow water created a much wetter environment, of highly enriched water, in soil contiguous to the stem than that prevailing in soil farther from the stem. This resulted in very pronounced effects on chemical properties of the soil under the tree. In A horizons there were progressive increases inward toward the stem in organic C, total N, exchangeable acidity, exchangeable K, CEC, and free Fe2O3; and progressive inward decreases in pH, exchangeable Ca, exchangeable Mg, and base saturation. In B horizons there were progressive inward decreases in pH, exchangeable Ca, exchangeable Mg, exchangeable K, CEC, base saturation, and free Fe2O3.
The Formation of Mixed Magnesium‐Aluminum Hydroxides In Soil Materials
Authors: Hunsaker V. E. , Pratt P. F.
Published: July 2010

Potentiometric titration curves show a buffer region in the vicinity of pH 8.2 to 8.5 when soil materials, which contain reactive forms of Al, are titrated in a Mg solution. This buffering is due to the formation of mixed Mg‐Al hydroxide. The product formed during the titration of gibbsite in 0.2N MgCl2 solution was identified as mixed Mg‐Al hydroxide by X‐ray diffraction analysis. The buffer region also appears when allophane, Al sesquioxide, and clay with exchangeable Al are titrated in Mg solutions. The reaction with exchangeable Al and Al sesquioxide is rapid, but the reaction requires several hours and even days with gibbsite and allophane. It is concluded that soils containing these and possibly other forms of Al, when raised to alkaline pH levels, can remove Mg from the soil solution by precipitation of mixed Mg‐Al hydroxide.
Nitrate and Detergent Recovery in Aerated Soil Columns
Authors: Mansell R. S. , Kirkham Don , Nielsen D. R.
Published: July 2010

The plant nutrient, nitrate, and the surfactant, linear alkylbenzene sulfonate (LAS), were applied in solutions to the surface of aerated columns (93 cm) of layered soil. Distilled water coutaining 0.01N CaSO4 was used to displace the nitrate and LAS through the columns while a steady water flow was maintained through the soil. The columns were water saturated at both extremities but unsaturated throughout most of the column length. Oxygen‐helium mixtures containing 0.2, 5, and 20% oxygen provided three different aeration levels. Recovery of nitrate in the liquid effluent was 73, 81, and 87% of that amount originally applied to the soil surface for the respective three levels of oxygen. Recovery of LAS was 50.4, 50.0, and 48.7% of the surface application for the same oxygen levels. These recovery results show that denitrification in a flowing soil‐air‐water system depended upon the level of oxygen, but the oxidation of LAS was not affected by the oxygen level. Actual times allowed to insure complete displacement of nitrate and LAS from the soil columns were 16.65, 15.42, and 17.67 days, respectively, for the 0.2, 5, and 20% oxygen treatments.
Effects of Alternating Versus Constant Soil Temperatures on Maize Seedling Growth
Authors: Walker John M.
Published: July 2010

The responses of maize seedlings (Zea mays, L.), which were grown with soil temperatures alternating ± 3C about 20, 23, and 26C means and also at equivalent constant soil temperatures, were compared. Soil temperatures were alternated about the means diurnally in synchronization with 12‐hour light and dark periods. Both the alternating and constant soil temperature treatments were applied when seedlings were 7 days old and were maintained for 16 days in a uniform aerial environment (25C air temperature).

Alternating soil temperatures about 23 and 26C means yielded more growth than was obtained at the equivalent constant soil temperature. These alternating soil temperature response data could be explained by relating the light, dark, and mean soil temperatures to the optimum constant soil temperatures for growth (leaf length growth was optimum at 20 to 23C, dry weight growth at 23C, and stem growth at 26C). Apparently, soil temperature most strongly influences growth during the light period (daytime) when a plant is photosynthesizing.
Separation of Adsorbed Cation Species as Water Flows Through Clays
Authors: Kemper W. D. , Sills I. D. , Aylmore L. A. G.
Published: July 2010

Theory predicts that adsorbed divalent cations move upstream and monovalent cations move downstream in a mixed ion system, when solutions of low concentration are forced through this clay. Data from small size mica support this prediction.
Response of Alfalfa to Boron in Flyash
Authors: Mulford F. R. , Martens D. C.
Published: July 2010

The availability of B in flyash obtained from three coalburning power plants was evaluated by greenhouse and laboratory procedures. The samples of flyash contained 319, 415, and 618 ppm B and neutralized 0.12, 0.58, and 3.05 meq H3O+/g, respectively. Boron in the samples of flyash was readily available to alfalfa (Medicago sativa L). grown on Tatum silt loam. Yield and B uptake data indicated approximately equal availability of B in flyash, 1N HCl extracts of flyash, and Na2B4O7 · 10H2O. Application of high rates of the flyash sample having the highest neutralizing power decreased yield of alfalfa. The decrease in yield was attributed to Zn deficiency of alfalfa plants induced by the increase in soil pH resulting from application of the by‐product.
Field Measurement of Unsaturated Hydraulic Conductivity by Infiltration through Artificial Crusts
Authors: Bouma J. , Hillel D. I. , Hole F. D. , Amerman C. R.
Published: July 2010

Field trials were made to test the applicability of a recently proposed method for measuring the unsaturated hydraulic conductivity (K) of crust‐capped soil materials in a one‐dimensional flow system, where the matric suction gradient is zero. K‐values were determined from infiltration rates into crust‐capped soil columns carved out in situ 30 cm in height. Matric suctions were measured with tensiometers. Examples are given for four Wisconsin soil horizons.
Soil Water Evaporation: Reduction by Simulated Tillage
Authors: Willis W. O. , Bond J. J.
Published: July 2010

Soil water loss with time as affected by simulated tillage to depths of 2.5 and 7.5 cm was measured from soil columns in a constant temperature room. The 60‐cm soil columns were initially wetted from the top to about 33% by volume and then covered for 2 days to prevent evaporation. Tilling was done at 1, 4, 7, and 18 days after the columns were uncovered. Tillage effectively terminated first stage drying, and evaporative losses were reduced by tilling. The highest reduction of evaporation was associated with earliest tilling, which showed over 50% reduction in evaporative loss for more than 22 days after tilling. The reduction in water loss was reflected in higher soil water content throughout the column length below the tilled layer. Evaporation reduction was only slightly better with 7.5‐cm than with 2.5‐cm tillage.
Field Measurement of Soil‐Water Content by Gamma‐Ray Transmission Compensated for Temperature Fluctuations
Authors: Reginato Robert J. , Jackson Ray D.
Published: July 2010

Soil‐water content under natural field conditions was measured with a gamma‐ray transmission technique that compensated for temperature changes. A spectrum stabilizer was needed for the nuclear counting equipment, and a knowledge of the relationship between peak count‐rate and the temperature of the gamma‐ray detector probe was required. Equipment and procedures to make field measurements of water content in 1‐cm‐thick soil layers are described. When the detector probe temperature varied 23C and gravimetric water content ranged from 0.021 to 0.186 gg‐1 over a measurement period, the average deviation of measured versus calculated values of water content was 0.009 gg‐1.
Differential Sr‐Ca Bonding on Soil as Influenced by Bonding Site
Authors: Elgawhary S. M. , Barber S. A.
Published: July 2010

The Sr‐Ca selectivity coefficient, kSr/Ca, was used to interpret the differential Sr‐Ca bonding of cation exchange sites in two soils. A dominant complementary cation, K, was used to place the Sr and Ca on sites which favored Sr and Ca over K. As the equivalent fraction of Sr plus Ca in the equilibrium solution was reduced, kSr/Ca decreased, indicating that organic exchange sites were the first to be filled. When the complementary ion was Mg or Ba, kSr/Ca was much larger, indicating that these complementary ions competed more nearly equally with Sr and Ca for all exchange sites. There was a relationship between the log of the equivalent fraction of Sr plus Ca and kSr/Ca that was linear over segments of the range of equivalent fraction used.

Chromatographic separation of Sr and Ca on a Sidell soil reflected the kSr/Ca of this soil at low Sr plus Ca saturations. Little Sr and Ca separation occurred with the Edwards muck apparently because of the over‐shadowing of the readily exchangeable cations by Sr and Ca adsorbed in very slowly exchangeable positions resulting in little movement of these ions.
Composition and Weathering of Loess Mantled Wisconsin‐ and Illinoian‐age Terraces in Central Ohio
Authors: Khangarot A. S. , Wilding L. P. , Hall G. F.
Published: July 2010

Elemental and mineralogical evidence indicate that both loess and outwash deposits on relatively high Illinoian‐age terraces are more intensively weathered than comparable units of lower level Wisconsin‐age terraces. The Illinoian site, particularly in the outwash paleosol, has lower weight percentages of heavy minerals; lower hornblende contents; lower elemental Fe, K, and Ca contents; and more pronounced pedogenic transformation of micas to partially or fully expandable 14Å components. Subtle weathering trends of elemental Ca, even in the Illinoian paleosol, are attributed to its occurrence in more resistant plagioclase‐feldspars. The 50‐20µ light mineral fraction (sp. gr. < 2.86) in both loess and outwash units contains appreciably higher quantities of Ti, Zr, and Fe than was originally anticipated. From 50–70% of the Ti, 20–45% of the Zr, and 85–90% of the total Fe occurs in light minerals. Essentially all of the K and 70–90% of the Ca also occurs in this isolate. Loci of Fe, Ti, and Zr in light minerals have not been established but are postulated to be either micro occlusions of primary minerals in host framework silicates or proxy for other metallic cations in these structures.
Use of Soil Cores in Determining Bulk Density
Authors: Goddard Tyrone M. , Runge E. C. A. , Walker W. M.
Published: July 2010

The bulk density of soil samples obtained with a hydraulic soil coring machine, for both core segments and clods, was compared to the bulk density of soil samples obtained with a Uhland sampler and natural clods taken from a soil pit. Subsurface, upper B, and lower B horizon samples were compared. Clods gave bulk density values that were significantly higher than cores in the upper solum, where small structural units occur; however, in the lower solum, where soil structural units are large or massive, variation between clods and cores was not statistically significant. There was no significant difference in bulk density due to the method of obtaining clods or cores.
Nitrate Adsorption: II. In Competition with Chloride, Sulfate, and Phosphate
Authors: Kinjo T. , Pratt P. F.
Published: July 2010

In anion‐exchange equilibria studies on two Andepts and one Oxisol, Cl‐ showed a slight preference over NO3‐, and SO42‐ and H2PO4‐ were greatly preferred over NO3‐. Negative adsorption of NO3‐ occurred when SO42‐ or H2PO4‐ exceeded certain concentrations. Under limited conditions, increases in Cl‐, SO42‐, or H2PO4‐ adsorption caused proportional decreases in the amounts of NO3‐ adsorbed. On a mmole basis, the decreases in NO3‐ adsorption equaled the increase in adsorption of other anions, except in the case of H2PO4‐, where about 3 to 4 mmoles of H2PO4‐ were adsorbed for a decrease in the adsorption of 1 mmole of NO3‐, suggesting that H2PO4‐ reacts with more sites of the same type and/or with types not available for NO3‐ adsorption.