bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Electrolyte Concentration on Donnan Systems and the Resulting Uptake of Cations by Plants
Authors: Franklin R. E. , McLean E. O.
Published: July 2010

Donnan systems were prepared by dialyzing bentonite and illite clay suspensions against equal volumes of water. The electrolyte concentration was varied from 0 to 10 me. per liter. Ca45 and Rb86 were used as tracers for Ca and K in the systems.

Greater amounts of Ca were absorbed by corn plants from the clay suspension phase than from the dialyzate phase provided that the electrolyte concentration was low enough. The differences in absorption from the two phases decreased as the electrolyte concentration was increased, and the uptake of Ca from the two phases was equal at about 0.1 symmetry concentration of electrolyte depending on the absorption time and saturation of the clay. A similar trend was observed for K absorption though less pronounced.

Various measurements supported the theory that clays have a low degree of dissociation and thus give rise to relatively small Donnan effects.

The apparent failure of Donnan theory to accurately describe clay‐water systems in studies by certain investigators was likely due to the assumption that the colloid is completely dissociated. In addition, differences or similarities observed in uptake of cations from suspensions and corresponding equilibrium dialyzates appear to be the result of variation in concentration of electrolyte present.
Response of Natural Stands of Shortleaf Pine to Thinning and Fertilization With Nitrogen and Phosphorus
Authors: Curlin James W.
Published: July 2010

This paper reports the results of fertilizer experiments conducted with thinned and unthinned natural stands of shortleaf pine. Nitrogen and phosphorus were applied singly and in combination on both thinned and unthinned plots. The plots were located on three soil series found in close association in the Great Valley Region of eastern Tennessee.

Four‐year response in basal area growth per tree was increased as much as 300% over the unthinned check by thinning and application of nitrogen. An increase of up to 40% over the thinned check was achieved with nitrogen alone. These responses were still evident 4 years after fertilization. Basal area growth response to phosphorus was erratic throughout the study period.

The results indicate that stand density must be low enough at the time of nitrogen application to allow growth to proceed unhindered.
Sorption of Cesium by Soils and Its Displacement by Salt Solutions
Authors: Coleman N. T. , Lewis R. J. , Craig Doris
Published: July 2010

Cesium was sorbed by montmorillonite, illite, and kaolinite in quantities corresponding to exchange saturation and was displaced readily on leaching with 1N KCl or CaCl2. Vermiculite and heated (600°C., 12 hours.) K‐montmorillonite bound Cs tightly against displacement by CaCl2 and AlCl3, but not by KCl or NH4Cl. Prolonged leaching with 1N KCl removed 97.5% of the Cs sorbed by heated K‐montmorillonite, while 1N CaCl2 eventually displaced 88%.

Potassium and Rb sorbed on vermiculite were displaced more rapidly by Ca or Mg than by monovalent ions, but this was not the case with heated K‐montmorillonite.

The exchange‐displacement behavior of Cs on vermiculite and heated K‐montmorillonite suggests that this ion is unique in that its sorption in interlayer spaces leads to interplanar distances which admit K and NH4 ions but greatly restrict the entry of Ca. Cesium, then, is not expected to follow the “fixation‐release” rules that have been developed for K and NH4.

Heated montmorillonite samples leached with mixtures of CsCl and other salts sorbed more Cs when the complementary ion was Ca or Al than when it was K or NH4. Differences were especially pronounced at low equivalent fractions of Cs in the leaching solution, showing a larger preference by exchange sites for Cs over divalent than over monovalent ions. Apparent “specific sorption” of Cs against exchange with CaCl2 occurred at quite large Cs saturations.
Availability and Fixation of Added Potassium in Two California Soils When Cropped to Cotton
Authors: Page A. L. , Bingham F. T. , Ganje T. J. , Garber M. J.
Published: July 2010

Field studies have recently demonstrated the occurrence of K deficiency in California cotton fields, and, further, unusually high rates of K fertilizers were required to correct the deficiencies. A greenhouse and laboratory study demonstrated that fixation of the added K was the reason high K applications were required. Two soils from problem fields were treated with K at rates ranging from 0 to 400 ppm. K and cropped to cotton in the greenhouse. Response, as indicated by plant analyses, plant symptoms, and yields, was not obtained until the application rate equaled or exceeded 160 ppm. K. Exchange and Rb‐fixation capacities of the soils after cropping showed a progressive decrease as a function of the added K. Disregarding the K removed by the crop and assuming the decrease in exchange capacities was due exclusively to K fixation, 63 to 75% of the added K was fixed. Laboratory studies demonstrated that soils in the moist state would fix up to 900 ppm. K against neutral salt removal. The effect of the added K on the Mg content of the cotton plant is also reported.
Pan Horizons in Southeastern Soils: Micromorphology and Associated Chemical, Mineralogical, and Physical Properties
Authors: McCracken R. J. , Weed S. B.
Published: July 2010

Certain Southeastern U.S.A. soils contain subsurface or subsoil horizons that differ from adjacent horizons by possession of one or more distinctive morphological features. Common terms for these are plowpan or traffic pan, brittle pan, organic pan, and fragipan. Results of micromorphologic studies of these pan types (claypans are excluded from this study) are reported, plus certain compositional characterization data to complement the thin section observations.

Brittle subsurface layers in the Norfolk soils were found to occur in two positions in the profile, immediately below the Ap horizon or plow layer and at or near the base of thick A2 horizons. The former may be induced by implement pressure; the latter may occur at depths of 6 and more inches below the base of the Ap but within the A2 or at A‐B contact and seems to be pedogenic. The term “brittle layer” has been used to describe the latter; “arenapan” is suggested as a name for these subsurface, coarse‐textured brittle zones.

Organic pans, as they are called locally, are apparent humus B horizons of Ground‐Water Podzols. Samples from the Leon soil were employed in this study.

Fragipan development in the Southeastern United States is typified in the Grenada soil, formed from Southern Mississippi Valley loess. The fragipan in this soil occurs at the base of the B horizon, below a zone of slight clay accumulation.

The Leon Bh (“organic pan”) and the brittle layers in the Norfolk A2 horizon show heterogeneous distribution of quartz sand separated by intergranular bridges of fine‐grained material. These pan layers appear highly porous in thin section, though many pores appear to be blocked by intergranular bridges. The Norfolk “plow pan” or traffic pan at the base of the Ap horizon exhibits close packing of quartzose sand and clay plus silt, with some humus inclusions. The Grenada fragipan is a close‐packed silty matrix containing a few areas of oriented clay and appreciable components of feldspar and mica.

A clay mineral species or complex of 14.7 A. basal spacing, expandable to 17 to 18Å. with ethylene glycol solvation following treatment for removal of interlayer aluminum, appears to reach maximum concentrations in the pan layers of all profiles studied except Grenada. In the Grenada profile, there is a maximum relative concentration of this clay mineral immediately above the fragipan.
Movement of Water as Effected by Free Energy and Pressure Gradients III. Restriction of Solutes by Membranes
Authors: Kemper W. D. , Evans N. A.
Published: July 2010

The validity and method of using the self‐diffusion coefficient of water to estimate movement in response to free energy gradients are outlined.

The dominant mechanism of water transport through these membranes is viscous flow, even when osmotic pressure differences are causing the flow. Osmotic pressure and hydraulic pressure differences are equally effective in moving water through a membrane when the solutes are completely restricted by the membrane. When solutes are not completely restricted, osmotic pressure differences are less effective than hydraulic pressure differences in moving water through membranes. Equations including the sizes of the solute molecules and the pores are developed which predict the rate at which osmotic pressure differences move water through uncharged porous media.
Non‐Darcy Behavior and the Flow of Water in Unsaturated Soils
Authors: Swartzendruber Dale
Published: July 2010

Corresponding values of flow velocity and moisture gradient were calculated for water flow in unsaturated soil, using a graphical analysis of moisture profiles obtained during horizontal absorption of water into air‐dry Salkum silty caly loam. Plots of flow velocity vs. moisture gradient were straight lines through the origin at the higher moisture contents, but Darcy proportionality did not hold at the lower moisture contents.

The observed deviations were of the same type as found in earlier studies for plots of flow velocity vs. hydraulic gradient for water‐saturated materials containing clay, and could be fitted by a modified flow equation developed previously for the water‐saturated materials. Physically, the non‐Darcy behavior is tentatively attributed to non‐Newtonian liquid effects caused by clay‐water interaction.

Consideration of diffusion‐type analysis from the stand‐point of non‐Darcy behavior shows that the diffusivity D becomes a function of moisture gradient w as well as moisture content θ. This provides a way of accounting for the nonuniqueness of D(θ) recently reported in the literature.
Evaluation of Microbial Activity in Soil Aggregate Stabilization and Degradation by the Use of Artificial Aggregates
Authors: Harris R. F. , Allen O. N. , Chesters G. , Attoe O. J.
Published: July 2010

A method for evaluating the mechanisms and factors involved in soil aggregate stabilization by microorganisms is introduced and data are presented to illustrate its use. This method involves the incubation of artificial soil aggregates of uniform and controlled physical and chemical properties, so that the effect of one or more variables of soil composition or environment on aggregate stability can be investigated.

The stabilities of differently‐amended artificial aggregates of two diverse soil materials, incubated for up to 20 weeks, were determined by wet‐sieving the dried aggregates. The two soil materials, one obtained from the Ap horizon of a Kewaunee silty clay loam (Gray‐Brown Podzolic) and the other from the Al horizon of a Waupun silt loam (Brunizem), differed markedly in their contents of clay, nitrogen and organic carbon.

Microbial gum‐amended Kewaunee aggregates possessed a higher initial stability and were more resistant to degradation with continued incubation than corresponding Waupun aggregates. Added nitrogen was associated with accelerated degradation of Kewaunee but not Waupun gum‐amended aggregates. Incubated sucrose‐amended Kewaunee aggregates showed a slower increase to maximum stability but retained stability longer than sucrose + nitrogen‐amended Kewaunee and sucrose‐ and sucrose + nitrogen‐amended Waupun aggregates. Nonamended and nitrogen‐amended aggregates of both soils were completely unstable throughout the incubation period. The stability of moist aggregates was a function of wetting rate and moisture status prior to sieving; aggregates moistened slowly to saturation were 100% stable to wet‐sieving.

Periodate treatment of the aggregates indicated that, with the exception of incubated sucrose‐amended Waupun aggregates, “periodate‐oxidizable” polysaccharides were important in aggregate stabilization.

Four days of incubation under highly aerobic or anaerobic conditions caused a rapid increase in the stability of sucrose‐amended Waupun aggregates. Continued aerobic incubation resulted in a rapid decrease in aggregate stability; aerobically incubated aggregates were totally unstable after 12 days. In contrast, continued anaerobic incubation was associated with an increase in stability; 100% aggregate stability was reached after 15 days and was still present after 4 weeks. Anaerobically‐stabilized aggregates lost their stability completely after 9 days of aerobic incubation.
Gray Wooded Soils of the Black Hills of South Dakota
Authors: Radeke R. E. , Westin Fred C.
Published: July 2010

The morphology, classification, and laboratory characteristics of the wooded soils of the Black Hills of South Dakota are reported. Field morphology studies involving parts of two summers tentatively established the classification of these soils in the Gray Wooded Soil Group. Paired profiles representing the central concept of the Gray Wooded group were sampled and laboratory characteristics determined. These soils resemble Gray Wooded soils reported for Canada, Montana, and the Northern Lake States. Additional paired profiles of giant or maximal Gray Wooded profiles and Gray Wooded intergrade profiles also were sampled and are characterized. A description of a pygmy or minimal Gray Wooded profile is described but was not sampled for analysis.
An Electric Point Gauge and Tube Orifice Plates for Measuring Flow Rates in Furrow Irrigation
Authors: Grover B. L. , Hotchkiss C. W.
Published: July 2010

The description of an electric point gauge and tube orifice plates for determining furrow flow rates is given. The gauge is a double‐pointed unit, constructed so that the head loss across the orifice plate is obtained as a single reading. The equipment is particularly useful in the evaluation of intake rates in furrow irrigation on small experimental plots, since it can be used with little or no damage to the plots.
Predicting the Solute Composition of the Saturation Extract from Soil Undergoing Salinization
Authors: Dutt Gordon R. , Doneen Lloyd D.
Published: July 2010

A procedure utilizing a 1620 IBM computer was developed to predict the concentrations of Ca2+, Mg2+, and Na+ in saturated extracts from soils undergoing salinization with waters containing Cl‐ and SO42‐ salts of one or more of the above cations. This procedure was used to predict the concentration in saturated extracts for soils to be salinized with various mixtures of salts. These predicted values were in agreement with experimentally determined values both in systems where the salts remained in solution and where gypsum was precipitated. This procedure lends itself to routine analysis, and it should be possible to extend it to include other ions and slightly soluble salts that frequently are found in nature.
Characterization and Genesis of Pawnee and Adair Soils in Southeastern Nebraska
Authors: Millet John L. , Drew James V.
Published: July 2010

Pawnee and Adair soils occur on gently sloping to rolling uplands in southeastern Nebraska. They have clay‐textured subsoils and are somewhat similar morphologically except that Pawnee soil has a yellowish‐brown subsoil, whereas Adair soil has a reddish‐brown subsoil. Montmorillonite and illite are important minerals in the clay fraction of these soils.

Field studies indicate that Pawnee soil has formed in Kansan glacial till whereas Adair soil has formed in poorly sorted and clayey material derived from Kansan till. This poorly sorted material overlies Kansan till and is identified in Nebraska as the colluvial phase of the Loveland formation. The Loveland formation often has a reddish‐brown color which is thought to be the result of weathering and soil formation during Sangamon time.

Petrographic data indicate that the subsoil of Adair soil is more weathered than the subsoil of Pawnee soil. These data suggest that Kansan till was protected from weathering during Sangamon time by colluvial and upland (eolian) phases of the Loveland formation. Pawnee soil occurs in places where Kansan till was exposed by subsequent geologic erosion whereas Adair soil occurs in clayey remnants of colluvial‐phase Loveland.
Salt‐Exchangeable and Titratable Acidity in Bentonite‐Sesquioxide Mixtures
Authors: Coleman N. T. , Thomas G. W. , LeRoux F. H. , Bredell G.
Published: July 2010

Abstracts

Precipitation of ferric or aluminum “hydroxides” in bentonite suspensions resulted in the formation of claysesquioxide complexes with exchange and titratable acidity reminiscent of many acid soils high in iron and aluminum oxides. Tenth‐normal AlCl3‐treated samples containing different amounts of sesquioxide had exchange acidities between 0 and 0.42 me. per g. of bentonite, titratable but nondisplaceable acidities from 0.41 to 0.74 me. per g. The sum of exchange and titratable acidity was close to the cation‐exchange capacity of the clay. Substantial amounts of aluminum or ferric hydrous oxide existed as interlayers, aluminum ones being better ordered. Apparently ferric or aluminum hydrous oxides deposited on montmorillonite surfaces can exist there as R(OH)x, with x ≤ 3. At pH 8 to 9, there are 3 hydroxyls per trivalent ion, and the effective CEC is that of the clay. As pH is lowered, OH is removed or H is added to the sesquioxide coating, which becomes positively charged and interacts with exchange sites of the clay. At pH around 5, the effective exchange capacity is near zero. Addition of base to the acid system restores OH to the sesquioxide and recreates exchange capacity. The salt displacement and titration results in the bentonite‐sesquioxide systems parallel in many ways similar observations made with acid soils, suggesting that similar reactions occur in natural and synthetic systems.
Crop Responses to Some Micronutrients and Sodium on Sphagnum Peat Soil
Authors: MacKay D. C. , Chipman E. W. , Langille W. M.
Published: July 2010

Five micronutrients and sodium were applied to a virgin sphagnum peat soil, having an initial pH of 3.5, in a 26 confounded factorial greenhouse experiment. To determine both immediate and ultimate deficiencies, a sequence of 11 crops were grown with spinach, lettuce and onions as the indicator crops. Yield data were supplemented by soil and crop analyses.

The greatest effect resulted from molybdenum treatment which produced yield increases over no molybdenum of 67, 42 and 198% with the 8th, 10th and 11th crops, respectively. The onion crop was the most responsive.

Copper had little effect on the first few crops, but with the 3rd application (on the 5th crop) serious toxicity resulted, and persisted until the 10th crop. A 63% yield increase from Cu was obtained with the final crop.

A highly significant interaction of Mo x Cu was obtained with the last three crops. Although the overall effect of Cu was negative, not significant and positive on the three respective crops, the interaction was consistently positive.

Repeated applications of manganese and zinc were toxic with yield depressions occurring on the 5th and persisting until the 11th crop.

Sodium was neither beneficial nor detrimental for any crop. Boron had no detectable effect in these experiments, but analytical results indicated that impurities added in the lime or fertilizers were sufficient to prevent serious deficiency.
Linear Equations for the Simultaneous Flow of Matter and Energy in a Continuous Soil System
Authors: Taylor Sterling A. , Cary John W.
Published: July 2010

Some transfer processes in soil are considered with respect to recent developments in the theory of thermodynamics of irreversible processes. The theory provides a general and systematic guide for setting up interrelated equations describing the transport of one or more components through soil. Darcy's law and the “diffusion equation” are shown to be components of this general development. Particular attention is given to the non‐isothermal flow of moisture and energy through soil. A general relation between the fluxes induced by the combined gradients of moisture content, temperature, and solutes is also suggested.
Microrelief Influences in a Saline Area of Glacial Lake Agassiz: I. On Salinity and Tree Growth
Authors: Sandoval Fred M. , Benz Leo C. , George E. J. , Mickelson R. H.
Published: July 2010

Considerable acreage of saline, imperfectly drained land in the northern Red River Valley of North Dakota has a gently undulating microrelief or nearly level topography. In slight to moderate saline lands the ridges are saline and the depressions relatively nonsaline. Salinity was studied in its relationship to microrelief under both shelterbelt and cultivated land use. Salinity in the ridge is composed primarily of magnesium and sodium sulfates. Exchangeable sodium is low and not a problem. Chemical compositions of shallow ground waters and saturation extracts of ambient soil are similar.

Soil salinity of the first foot of soil was less in the shelterbelt than in the adjacent cultivated area. This reduction near the surface within the shelterbelt was accompanied by a salinity increase at the 42‐ to 60‐inch depth. The reduction was attributed to greater moisture absorptive qualities of the established grassed areas and increased water supply from snow accumulation in the belt. Russian olive shrubs did poorly and frequently failed to survive when planted in soil having more than 10 millimhos per cm. estimated electrical conductivity, but they experienced little detrimental effects with 3 millimhos per cm. or less. Salinity of shallow ground water was much higher under ridges than depressions which indicates very limited crossflow.
Physiological Changes in and Ozone Susceptibility of the Tomato Plant After Short Periods of Inadequate Oxygen Diffusion to the Roots
Authors: Stolzy L. H. , Taylor O. C. , Dugger W. M. , Mersereau J. D.
Published: July 2010

The degree to which tomato leaves were altered following short periods of reduced oxygen in the root zone was studied in relation to the following factors: apparent rate of photosynthesis, susceptibility to ozone, and carbohydrate concentration.

Reduced rates of soil oxygen diffusion for 8 ½ hours brought about a 50% decerase in CO2 fixation by plants, while shorter periods (3 hours) had only a slight effect on apparent photosynthesis. However, the short period of anaerobic treatment over the soil surface, followed by normal soil aeration for 24 hours, reduced the susceptibility of the plant to ozone damage by as much as 50%. Carbohydrate analysis of leaf tissue for similarly treated plants showed a 50% reduction in sucrose and 33% reduction in starch. It is hypothesized that the anaerobic pretreatment brought about a change in the root membrane permeability or a shift in metabolism that promoted excretion of certain carbohydrates from the roots which in turn changed the concentration of carbohydrates in the leaves.
Reduction in Salt Content of Solution on Passing Through Thin Films Adjacent to Charged Surfaces
Authors: Kemper W. D. , Maasland D. E. L.
Published: July 2010

An equation was derived to measure the effect of salt and water diffusion on salt reduction of solutions forced through thin films of water by pressure differentials. Salt concentrations of solutions which had passed through thin films adjacent to charged particles were calculated from the equation and are plotted as a function of pressure differential, ionic mobility, film thicknesses, and cation valences. Experimental evidence showed that salt sieving increases as the pressure forcing solution through the clays increases. Salt sieving generally increases as the pores through which the water flows decrease in size, and is smaller when the soil is saturated with divalent rather than monovalent ions. These observations were in agreement with the theory.
Availability of P from Superphosphate to Spring Wheat as Affected by Growth Stage and Surface Soil Moisture
Authors: Boatwright G. O. , Ferguson Hayden , Brown Paul L.
Published: July 2010

The influence of periodic wetting of a dry surface soil on fertilizer P uptake at four growth stages was studied in the greenhouse using P32.

Wheat plants did not absorb fertilizer P from a dry soil. At all stages of growth there was a lag in fertilizer Pu ptake after watering and the length of lag increased with age of plant after the flag leaf stage. Only small amounts of fertilizer P were found in plants grown on soil that had been wet less than 80 hours. This suggests that showers and weather conditions which do not allow the fertilizer zone to remain wet for 3 to 4 days contribute little to fertilizer P uptake by wheat. Most rapid rate of fertilizer P uptake occurred when fertilizer and water were added at the flag leaf and 30% headed stages of plant growth, but when added at the completely head stage little fertilizer P was absorbed.
The pH‐Percent Base Saturation Relationships of Soils
Authors: Clark J. S. , Hill R. G.
Published: July 2010

The curves obtained by plotting pH‐½p (Ca + Mg) against percent base saturation calculated from the ratio of exchangeable Ca + Mg to the sum of Ca + Mg + Al + H extracted from soils with 1.0N KCl had the characteristic shapes of clay titration curves. The experimental values for some montmorillonitic soils showed close agreement with the theoretical curve calculated for Al‐bentonite. The Podzolic and Glei soils fell along another curve with lime potential values higher than those for the montmorillonitic soils at the same % base saturation indicating that the exchange properties of the soils differed from those of bentonite. No close relation was observed when the cation‐exchange capacity (CEC) obtained with 0.9N Ca(OAc) 2 + 0.1N CaCl2 or with 1.0N CaCl2 was used to calculate percent base saturation.
Gamma Radiation Compared with Steam and Methyl Bromide as a Soil Sterilizing Agent
Authors: Eno Charles F. , Popenoe Hugh
Published: July 2010

Red Bay loamy fine sand and Everglades muck were sterilized with gamma radiation, steam, and methyl bromide. Exchangeable NH4+; extractable N, P, and S; moisture equivalent; cation‐exchange capacity; and organic matter were measured. None of the sterilization treatments significantly altered cation‐exchange capacity. Steam significantly increased the amounts of N, P, and S extracted and the organic matter content values, compared to the check and the other two soil treatments; it also significantly decreased the moisture equivalent percentage. Gamma ray and methyl bromide sterilization generally increased the release of N, P, and S above the check. There was also a strong indication, based on the N data, that sterilization by gamma rays disrupted the soil organic materials more than methyl bromide. Finally, the intensity of all these factors is most closely associated with the organic matter content of the soil. Therefore, a sand, for example, would not be altered nearly as much as a loam or an organic soil.
The Temperature Dependence of Soil Water Vapor Pressure
Authors: Kijne Jacob W. , Taylor S. A.
Published: July 2010

The temperature dependence of soil water vapor presure was studied with a psychrometric vapor pressure technique in the range of 0.96 to 1.00 relative vapor pressures and below 0.96 with gravimetric and calorimetric heat of immersion techniques. For Millville silt loam at constant water content, the relative vapor pressure decreased with increasing temperature. Both differential and integral entropy values were calculated. The difference between the partial molar entropy of pure free water vapor and the partial molar entropy of adsorbed water led to the conclusion that soil water molecules are arranged, on the average, less randomly than water vapor molecules. At the same time, comparison with the entropy of vaporization of pure water suggested a more random arrangement of molecules in soil water than in free liquid water.
Relationship of Exchangeable Na Percentage at Different Soil pH Levels to Hydraulic Conductivity
Authors: Martin J. P. , Richards S. J. , Pratt P. F.
Published: July 2010

The relation of exchangeable Na percentage at different soil pH levels to the hydraulic conductivity of 6 soils with exchange capacities varying from 7.5 to 50.8 me. per 100 g. was studied. The same quantities of Na reduced hydraulic conductivity more in acid than in neutral or alkaline soils. This response was studied further by correlating hydraulic conductivity with Na percentage calculated relative to each of three quantities: (1) the cation‐exchange capacity (CEC) at pH 7, (2) the CEC at the pH of the soil sample, and (3) the sum of exchangeable Ca, Mg, K, and Na. Highly significant correlation coefficients relating hydraulic conductivity to Na percentage were obtained for all six soils when Na was expressed as a percentage of Ca + Mg + K + Na. Calculation of the Na percentage on the basis of the CEC at the pH of the soil and at pH 7 gave highly significant correlation coefficients in 4 and 2 soils, respectively.
Volatilization Losses of Nitrogen from Surface‐Applied Fertilizers, as Measured by Crop Response
Authors: Terman G. L. , Hunt C. M.
Published: July 2010

Yields and uptake of N by corn forage grown in pot experiments with N fertilizers mixed with and surface‐applied to moist soils a week prior to planting were determined. Losses of N were low with mixed placement. High losses of N, presumably as NH3, occurred from granular urea surface‐applied to Hartsells fine sandy loam limed to pH 6.2 and 7.5 and to Webster silty clay loam (pH 8.2). Losses were reduced by coating urea with S or by including phosphate in the granules as urea ammonium phosphate. Severe losses of N also occurred with surfaceapplied ammonium sulfate and diammonium phosphate, especially from the naturally calcareous Webster soil. Maximum recoveries from soils of pH 6.2 to 8.2 were obtained from monoammonium phosphate, ammonium nitrate, ammonium phosphate nitrate, and ammonium polyphosphate. Differences in losses of N as NH3 among N fertilizers can be explained largely in terms of urea hydrolysis or the reaction of certain acid radicals of ammonium salts with calcium compounds in soil.
Classification and Genesis of Some Solonetz (Sodic) Soils in Eastern Arkansas
Authors: Horn M. E. , Rutledge E. M. , Dean H. C. , Lawson M.
Published: July 2010

Medium‐textured Solonetz soils, comprising an estimated 600,000 acres in Arkansas, are extensively developed in loess and backwater alluvial deposits of eastern Arkansas. Three general groups are recognized: (1) Soils of less than about 10 inches depth to a sodic horizon, (2) soils with acid upper horizons and moderate depth (about 24 inches) to a sodic horizon, and (3) soils with sodic horizons and acid sola. Laboratory analyses of Lafe and Foley soil profiles indicate that their sodic horizons contain high percentages of exchangeable Na (15 to 40% or more) and Mg (40 to 50% or more) with electrical conductivities ranging up to 5 mmho. per cm. These horizons are commonly characterized by prismatic or columnar structure. It appears that these soils are undergoing leaching and that soils of high exchangeable Na and solonetz morphology are probably the result of prior high Na content.
The Effect of Fatty Alcohol and a Nonionic Surfactant on Soil Moisture Evaporation in a Controlled Environment
Authors: Law J. P.
Published: July 2010

Evaporation studies have been conducted in a controlled environment chamber. Three variables were introduced: Treatment rate, relative humidity, and wind velocity. Air temperature was held constant at 100°F. Two evaporation media were employed: washed masonry sand, and Amarillo fine sandy loam soil.

The fatty alcohol used in the study was a commercial mixture of hexa‐ and octadecanol, which was uniformly mixed with the top 3‐inch layer of soil. The rates of application were: 100, 200, and 400 pounds per acre with the masonry sand, and 200 and 800 pounds per acre with the sandy loam soil. A third treatment with the soil consisted of irrigating the column with a 0.1% solution of a nonionic surface active chemical. The control in each case consisted of untreated sand or soil. All columns were irrigated and drained to approximately field capacity at the start of each drying cycle. Evaporative loss was measured by weighing.

Fatty alcohol effectively reduced evaporation from the sand surface up to a maximum of 87% at 400 pounds per acre, at 20% relative humidity, and 2 miles per hour wind velocity. The greatest reduction with soil was 24% at 800 pounds per acre, at 20% relative humidity, and 2 miles per hour wind velocity. The nonionic surfactant reduced evaporation from the soil surface up to a maximum of 52% at 60% relative humidity and 8 miles per hour wind velocity.

Increased relative humidity reduced evaporation rates in all cases. The higher wind velocity accelerated the evaporation process, causing the earlier formation of a dry diffusion barrier at the surface.

The mechanism by which the fatty alcohol suppressed evaporation from the masonry sand appeared to be essentially the same as that which acts to reduce evaporation from an open water surface. With the soil, the mechanism appeared to be that of reducing capillary flow of moisture to the soil surface. The treated soil formed a dry layer at the surface sooner than the control.

The action of the nonionic surfactant in reducing evaporation was probably due to decreased surface tension at the solid‐liquid interface, thereby reducing capillary flow to the surface layer of the soil, and causing the formation of a dry diffusion barrier.
Water Movement and Loss Under Frozen Soil Conditions
Authors: Ferguson Hayden , Brown Paul L. , Dickey David D.
Published: July 2010

Soil water and temperature distributions in a silty clay loam soil were studied in the field under freezing winter conditions. Appreciable upward water movement to a frozen zone occurred in plots in which the unfrozen subsoil water was held at tensions of less than about 2 atm. and water held at tensions of less than 5 atm. moved toward the frozen zone. It appears that the upward water movement to the frozen zone conributed to overwinter water losses since soil water losses of 0.36 and 0.50 inches were measured from those plots in which there was appreciable upward water movement. Plots containing 7.9, 6.2, 4.2, and 1.4 inches of available water before freezing occurred conserved −0.36, −0.50, 0.0, and 0.81 inches, respectively, of the 4 inches of precipitation that occurred during the winter.
Effect of Small Amounts of Gypsum in Soils on the Solutes in Effluents
Authors: Dutt Gordon R.
Published: July 2010

Columns of soil initially containing exchangeable Ca2+ and 0.0, 0.5, 1.0, and 2.0% CaSO4·2H2O by weight were leached with a solution containing 50 me. NaCl and 50 me. MgCl2 per liter. The effluents from these columns were collected and analyzed for Ca2+, Mg2+ and Na+. The breakthrough curves for Na+ were not affected significantly by the presence of gypsum; however, the curves for Mg2+ were dependent on the amount of CaSO4·2H2O present in the system. When small amounts of gypsum were present, Mg2+ concentration in the effluent increased and then leveled off at some concentration below that of the solution entering the column. The length of the plateau and the concentration at which it occurs are functions of the amount of gypsum present in the system. When the gypsum was leached from the system, the Mg2+ concentration increased to a value approaching the concentration of the solution entering the soil.

A general method for calculating the ionic composition of the effluent from initial conditions was developed. It was found that theoretical values calculated by this computer method approximated those found experimentally.
Cyclic Variations and the Pedon
Authors: Arnold R. W.
Published: July 2010

The applicability of utilizing a half‐cycle width as a pedon limit for soils having cyclic horizon variations is analysed using a sine curve as a model. The low probabilities of success associated with the half‐cycle limit, even when accepting ranges less than the total observed vertical variation, indicates a practical width limit of approximately 0.8 cycle.

A method for determining the width of a pedon necessary to include an acceptable range of horizon variability is given. Included in the method is a visual technique for estimating some pragmatic limits of variations of horizon thicknesses. This method of determining pedon widths is illustrated using a hypothetical soil cross section.

Some implications of determining pedon size for soils having cyclic horizons are intermittent or cyclic and recur at linear intervals of about 1.3 to 4.3 m. the pedon should include 80 to 90% of the vartical horizon variability and have lateral dimensions of approximately 0.8 of a cycle.
Mechanisms for Hydrogen to Aluminum Transformations in Clays
Authors: Miller Raymond J.
Published: July 2010

The rates of Al release from montmorillonite and kaolinite clays by acid‐dissolution techniques were determined. For kaolinite the release of Al obeyed pseudo zero order kinetics and form ontmorillonite the release of Al obeyed pseudo first order kinetics. The kinetic studies indicate a difference in mechanism of H attack on these two clays. A diffusion controlled edge attack is proposed in the case of kaolinite and an all surface attack is proposed for montmorillonite. Kinetic studies using different size fractions of the two clays support the proposed mechanisms.
Effect of Lime and Potassium Additions on Soil Potassium Reactions and Plant Response
Authors: Powell A. J. , Hutcheson T. B.
Published: July 2010

Lime and/or wetting‐drying cycles following its application to soils of micaceous mineralogy resulted in lower exchangeable K levels, as measured by N NH4OAc extraction, which were closely correlated with K levels before liming. K level changes were not related to initial pH levels over a range from pH 4.7 to 6.2. Liming effects on exchangeable K levels were not reflected by crop response or uptake of K. Release of nonexchangeable K was enhanced and fixation of applied K was prevented by lime applications. It is suggested Ca2+ ions may prop open edges of clay mineral packets, thus preventing entrapment of K+ ions and releasing previously “trapped” or lattice K.
Ion Gradients and Nitrification Associated with Decomposition of a Plant Material Layer in Soil
Authors: Smith J. H. , Burns G. R.
Published: July 2010

Changes in the pH and in concentrations of ammonia, NO2‐, NO3‐, and K+ with distance from layers of decomposing leguminous plant material in Red Bay sandy loam soil were measured after 16 days' incubation. High concentrations of ammonia (2.7 meq/100 g) and of K+ (1.4 meq/100 g) were found near the plant material layer. Nitrification was inhibited and NO2‐ was found in this zone. Farther away, NO3‐ accumulated. A change in pH from 8.9, near the layer, to 5.6, about 4 cm away, was observed. Treatment with CaCO3 decreased the pH range and increased nitrification. When the decomposing plant material layer was separated from the soil on one side by an air space, NH3 diffused across the air space. This resulted in segregation of some of the NH3 from the cations and other potentially toxic substances and lowered the overall toxicity to nitrification. Besides the toxicity observed, the availability of plant nutrients as well as growth of microorganisms and plant roots could be drastically affected by pH and cation concentration changes found near layers of decomposing plant material.
Biological Assay of Pumice Soil Fertility
Authors: Youngberg C. T. , Dyrness C. T.
Published: July 2010

The fertility of pumice soils is difficult to assess by laboratory analysis. A biological assay of growth responses yields more meaningful information. Four pumice soils common in central Oregon were assayed in the greenhouse using ponderosa pine as an indicator species.

A composite experimental design was used involving additions of N, P, K, Ca, and S. There were no responses to either K or Ca. Nitrogen appeared to be the most deficient nutrient element since it was the only one tested that gave large responses when added alone. Combinations of N and P and N and S gave better responses than N alone. Best growth resulted from addition of N, P, and S in combination. The experimental design used was very satisfactory for this type of assay, particularly in evaluating various nutrient interactions.
Water Permeability of Saturated Soils as Related to Air Permeability at Different Moisture Tensions
Authors: Aljibury F. K. , Evans D. D.
Published: July 2010

The relationship among soil moisture tension, air permeability, and water permeability at saturation was determined for several disturbed soil samples ranging in texture from coarse sand to clay loam. A typical graph of tension versus air permeability shows that a slight tension is necessary before the air permeability is different from zero. With increasing tension, air permeability increases sharply until it levels off near the value of water permeability. The air and water permeabilities are nearly the same for tensions > 100 cm of H2O, unless cracking occurs. Then air permeability greatly exceeds water permeability.

Air permeability at field moisture percentages and water permeability of saturated soil were determined for soil cores of known soil moisture tension. As with disturbed samples, the two permeabilities were nearly the same at tensions of 100 cm of H2O.
Variation in Foliage Composition and Diameter Growth of Yellow Birch with Season, Soil, and Tree Size
Authors: Hoyle M. C.
Published: July 2010

Foliage samples and diameter measurements were taken periodically from yellow birch (Betula alleghaniensis) trees on well‐drained Hermon and poorly drained Whitman soils. Foliar analyses were made to determine seasonal changes in composition, and differences between trees and soil series. Leaf weights increased with season and were higher on the Whitman. Leaf moisture trends reflected soil moisture regimes. Nutrient percentages decreased during early June. Thereafter N, P, S, and K percentages flucturated slightly until September, then decreased until abscission, while Mg fluctuated considerably and Ca increased steadily. Absolute amounts of all six elements increased during June. Nitrogen, P, S, and K varied slightly during summer and decreased prior to leaf yellowing. Total Mg reached peak values in August and then decreased while total Ca increased continually. Total P, K, and S was comparable on both soils. Total N, Ca, and Mg was higher on the Whitman. Greater diameter increments of study trees were also recorded on the Whitman soil. The total content expression provided more meaningful information than nutrient percentages. Specific periods of sampling birch foliage are given.
Influence of Different Diffusivity‐Water Content Relations on Evaporation of Water from Soils
Authors: Hanks R. J. , Gardner H. R.
Published: July 2010

Estimates of the influence of variations in the diffusivity‐water content relation on evaporation showed that where the diffusivity was changed at high water contents, evaporation was changed accordingly. However, variations in the D(θ) relation at lower water contents showed little influence on cumulative evaporation.

Estimates were also made for layered soils with the D(θ) relation for one layer 10 times that of the other layer. Cumulative evaporation increased significantly, if the diffusivity of the bottom layer was greater, as the depth of the surface layer decreased, provided the surface layer depth was less than half the total depth of the soil. Where the diffusivity was greater for the surface soil, cumulative evaporation increased as the depth of the surface layer increased.

All of the estimates were made based on the assumption that a diffusion‐type equation is valid for evaporation.
Migration of Interlamellar Water During Freezing and Thawing of Wyoming Bentonite
Authors: Anderson Duwayne M. , Hoekstra Pieter
Published: July 2010

Homoionic, clay‐water pastes of Wyoming bentonite were studied at near freezing temperatures by X‐ray diffraction. On freezing, the initial high d(001) spacings of the lithium‐ and sodium‐bentonite pastes decreased, first to about 19A and at about −10C to 16A. When the temperature was raised the d(001) spacings of the frozen clays increased substantially; on melting, the d(001) spacings quickly expanded to their initial high values. The behavior of the hydrogen‐aluminum‐, potassium‐, and calcium‐bentonite was similar except that spacings greater than about 20A did not occur. All the normally observed diffraction maxima of ordinary ice were present after lattice collapse. No anomalous diffraction maxima suggesting the presence of ice having an unusual crystallographic structure were detected. Evidently, when bentonite‐water pastes are frozen all but two or three monomolecular layers of the interlamellar water migrates into the pore space to form ordinary ice. The remaining interlamellar water therefore must correspond to the “unfrozen” water of previous investigations.
Diffusion of Potassium‐40 Into an Illite During Prolonged Shaking
Authors: de Haan F. A. M. , Bolt G. H. , Pieters B. G. M.
Published: July 2010

The diffusion of K40 into the clay crystal lattice of an illite was studied at equilibrium concentrations comparable to those occurring under field conditions. Time of equilibration was extended over 16 months. The self‐diffusion constant was found as roughly 1–3 × 10‐23 cm2 sec‐1; the equivalent depth of penetration during the period of investigation amounted to a few Angstroms only.
Yield and Nutrient Uptake by Corn (Zea mays L.) for Silage on Two Soil Types as Influenced by Fertilizer, Plant Population and Hybrids
Authors: Robertson W. K. , Hammond L. C. , Thompson L. G.
Published: July 2010

The influence of corn hybrid on forage yield, nutrient composition, uptake of nutrients and percentage recovery from the fertilizer were studied at three plant populations and four fertilizer rates. Multi‐eared hybrids yielded more forage than single‐eared hybrids but tall growing hybrids did not always produce more than shorter growing hybrids. Increasing plant population had no significant effect on nutrient composition but did increase yields and uptake of N, P, and K. Corn hybrids differed widely in the amount of fertilizer they recovered. For 7 hybrids of corn, averaging 13,900 lb of dry forage/acre the average uptake of N, P, and K was 177, 25, and 242 lb, respectively. On nonirrigated soils a tall‐growing hybrid did not respond to fertilizer or plant population as did a short‐growing hybrid.
Retention of Acetate by Montmorillonite
Authors: Bingham F. T. , Sims J. R. , Page A. L.
Published: July 2010

Acetate retention was measured by treating suspensions of montmorillonite with C14‐labeled acetate solutions, removing excess acetate by washing with methanol, and determining the acetate remaining by C14 assay of the clay. The amount of acetate retained by montmorillonite was found to be dependent upon the concentration of salt used, pH of the system, and concentrations of competitive anions.

Maximum acetate retention (0.05 meq acetate/g clay) occurred over the pH range of 2 to approximately 6. Increases in pH above 6 resulted in marked reductions in acetate retention. Under uniform conditions of pH (≅ 5.5), concentrations of approximately 2n acetate salts were required to attain maximum retention, irrespective of salt source. Release studies showed OH‐, F‐, and H2PO4‐ to be effective in removing sorbed acetate. On the other hand, SO42‐ was only partially effective while NO3‐ and Cl‐ were ineffective in releasing acetate.