bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of Ureaform Fertilizer Using Nitrogen‐15‐Labeled Materials in Sandy Soils
Authors: Brown M. A. , Volk G. M.
Published: July 2010

A quantitative account of labeled ureaform and ammonium nitrate fertilizer N was made in outdoor lysimeters, greenhouse pots, and laboratory incubation vessels. A major portion of the labeled fertilizer N applied to lysimeter and greenhouse pots was recovered by crops. A greater proportion of labeled ammonium nitrate N was recovered in the plants than labeled ureaform N. However, more labeled N was found in the soil after 1 year when ureaform was the source. As a result, there were no differences in total recovery of labeled N in plants plus soil between sources. Approximately half of the N in the ureaform used in these studies was in a state of availability approaching that of ammonium nitrate. Extended availability of ureaform N over ammonium nitrate N was only apparent at the high rate of ureaform application. Approximately 15 to 20% of the ureaform material remained apparently unchanged in the soil after 1 year.

Unaccounted for N is thought to have been lost as a gas after it entered the organic N complex of the soil, since similar total recoveries were obtained for ammonium, nitrate, and ureaform N. Under anaerobic conditions significant quantities of N were lost from soils incubated with ureaform as well as from soils incubated with ammonium nitrate.
Soil‐Moisture Measurement by the Neutron Method in Rocky Wildland Soils
Authors: Koshi Paul T.
Published: July 2010

To accurately interpret moisture readings taken by the neutron‐scattering technique in rocky soils, methods of access tube installation, influence of voids and rocks around access tubes, and accuracy of factory calibration curve were evaluated. Because access tubes could not be installed by the hand‐auger method where hard rocks were present, power‐driven portable drilling rigs were tried. Vacuum evacuation of cuttings in wet soils failed. Water injection worked well except in the presence of loose rocks. Air injection was most satisfactory except in wet clays. Voids around access tubes of < ⅜ inch had little or no influence on slow neutron count rates. Rocks had little influence on soil moisture determination unless they were large. Because readings of soil moisture from factory calibration seemed too high, a laboratory calibration curve was developed.
Influence of Applied Sulfur on Availability of Soil Nutrients for Corn (Zea mays L.) Nutrition
Authors: Hassan Nouri , Olson R. A.
Published: July 2010

Influence of applied sulfur on soil properties and nutrient uptake was studied on three soils ranging from acid to calcareous with growth of corn in the greenhouse. The heaviest rate of 5,000 ppm S produced toxic effects on the acid and neutral soils, a consequence of sharp pH reduction and excessive S and Manganese uptake. Otherwise, S treatment had beneficial effects on: Phosphorus nutrition on neutral and calcareous soils; S and Mn nutrition (up to modest rate of S) on all soils; zinc in early nutrition on all soils with slight benefit carrying over to late harvest only on calcareous soil; iron nutrition on calcareous soil; and copper nutrition until early harvest with all soils and through late harvest with neutral and calcareous soils. With a low rate of 50 ppm S, mixing was more efficacious than banding on all soils.
Effect of Solution Composition on Soil Hydraulic Conductivity
Authors: McNeal B. L. , Coleman N. T.
Published: July 2010

Decreases in hydraulic conductivity with decreasing electrolyte concentration and increasing sodium adsorption ratio (SAR) of the percolating solution were assessed for seven soils of varying clay mineralogy. The decreases were particularly pronounced for soils high in 2:1 layer‐silicates, with the most labile hydraulic conductivities being exhibited by those soils containing the most montmorillonite. A soil containing considerable amorphous material was much more stable then the average, and a soil high in kaolinite and sesquioxides was virtually insensitive to variations in solution composition. No property of the solution alone was sufficient to characterize the response of the soils to a given solution, though expression of results in terms of the exchangeable sodium percentage (ESP) of the soil and the total salt concentration of the ambient solution produced more nearly similar curves for soils of similar clay mineralogy. The soils commonly demonstrated rather pronounced hydraulic conductivity decreases in the ESP range of 20 to 35 at salt concentrations of 3 to 50 meq/liter. The decreases were largely irreversible upon the reapplication of high salt or high Ca solutions to the soil, except for those soils containing greater than 10% montmorillonite on a whole‐soil basis.
Effect of Solution Composition on the Swelling of Extracted Soil Clays
Authors: McNeal B. L. , Norvell W. A. , Coleman N. T.
Published: July 2010

For soils containing expansible minerals, the swelling of extracted soil clays in mixed NaCl‐CaCl2 solutions was well correlated with relative hydraulic conductivity of the soils to the same solutions, and with theoretical interlayer swelling values based on a “domain” model. In this model, mixed Na‐Ca clays were considered to consist of discrete Na‐ and Ca‐regions, with only the Na‐regions swelling at low salt concentrations. The correlations suggest that the most plausible mechanism for hydraulic conductivity decreases in soils containing significant amounts of expansible minerals is the closing of conducting pores by insitu mineral swelling. However, a dispersion process activated by the interlayer swelling of expansible minerals would also be compatible with the data.
Reactions of Surfactants with Montmorillonite: Adsorption Mechanisms
Authors: Law J. P. , Kunze G. W.
Published: July 2010

Four clays were treated with each of eight surfactants at three treatment rates. Volclay and the clay fraction from two montmorillonitic soils were treated with 100, 50, and 10 mmol /100 g.; and kaolinite was treated with 10, 5, and 1 mmol /100g.

Adsorption was measured quantitatively by the thermogravimetric method. Adsorption mechanisms were investigated by X‐ray diffraction and differential thermal analysis.

The surfactants included three anionic, three cationic, and two nonionic compounds. The anionics were not adsorbed in appreciable quantities and anion exchange of kaolinite appeared to be equal to or somewhat greater than that of montmorillonite. Anionics had no effect on the d‐spacing of montmorillonite and did not interfere with hydration of clay surfaces.

Cationics were strongly adsorbed by the clay surfaces through ionic bonding in amounts equal to or even greater than the cation‐exchange capacities of the clays. The excess material was probably held by van der Waals forces between the alkyl radicals which increased with chain length. Their presence on clays significantly reduced hydration and water content to the extent of making the clay surfaces completely hydrophobic at the high treatment rates.

Nonionics were adsorbed by hydrogen bonding of polar‐active groups to oxygen‐rich clay surfaces. Their sorption energies were somewhat greater than that of water, and they displaced water when adsorbed. Both cationic and nonionic compounds were held in the interlayer spaces of montmorillonite and tended to form double layers if sufficient material was present.
Reactions of Surfactants with Montmorillonitic Soils
Authors: Law J. P. , Bloodworth M. E. , Runkles J. R.
Published: July 2010

Two montmorillonitic soils were treated with each of eight surfactants at three treatment rates: 1%, 0.1%, and 0.01% by weight. The effects of the treatments on certain important physical properties of the soils were investigated by means of aggregate stability analysis, capillary rise measurements, and modulus of rupture.

The surfactants included three anionic, three cationic, and two nonionic compounds. The anionics were not strongly adsorbed by the soils. When the soils were dried in contact with them, they were weakly held and readily released to the liquid phase upon rewetting. Their effects on soil physical properties were directly related to the lowering of surface tension of the liquid phase, and the magnitude of the effect was strongly dependent on treatment rate.

The cationics were strongly adsorbed by the soil exchange complex and not readily released upon rewetting. Their effects on soil physical properties were directly related to the degree of hydrophobicity imparted, which increased with alkyl chain length and amount of material added to the soil.

The nonionics were adsorbed by hydrogen‐bonding to clay and other oxygen‐rich mineral surfaces. Their sorption energy was somewhat greater than that of water, and they displaced water from the surfaces. Their effects on soil physical properties were small and in proportion to the amount of chemical added. Those effects were related to reduced hydration of surfaces and the hydrophilic centers associated with the nonionic compounds.
Nitrification by Heterotrophic Soil Microorganisms
Authors: Doxtader K. G. , Alexander M.
Published: July 2010

Heterotrophic soil bacteria, actinomycetes, and fungi produced nitrite when grown in media containing various reduced forms of nitrogen. Amines, amides, N‐alkylhydroxylamines, oximes, hydroxamic acids, and aromatic nitro compounds served as substrates for nitrite formation by individual microorganisms. The yield of nitrite varied with the organism and the substrate, ranging from 190 ppm of nitrite‐nitrogen with acetaldoxime as a nitrogen source to a few ppm with certain substituted ureas. None of the microorganisms formed nitrate from the substrates tested. One isolate, identified as a species of Fusarium, converted more than 90% of the nitrogen of pyruvic oxime to nitrite. Cell extracts of the fungus catalyzed the production of nitrite from the oxime.
Phosphorus Status of Horizons of Four Benchmark Loessial Soils of the Central Great Plains Region
Authors: Black A. L. , Whitney R. S.
Published: July 2010

Genetic horizons of the Colby, Weld, Rago, and Keith loessial soil series were investigated. Buried soils occurred in the Rago and Keith series. Each horizon was subjected to various chemical analyses and used in greenhouse fertilizer studies.

Marked differences in P content and availability to plants occurred among horizons and with profile depth. Yields and plant uptake of N and P from nonphosphated horizons were positively correlated with the initial NaHCO3‐soluble P in the soils when N was uniformly applied. By adding 8.8 or 35.2 ppm P per pot, yields were similar within a given horizon, but differed markedly among horizons of the same profile. With adequate N added, spring barley (Hordeum vulgare L. ‘Moravian’) yields from the Rago A‐B subsoil horizon and the Rago Ap surface soil were similar, but the Weld B3ca subsoil horizon yielded 50% more than the Weld Al surface soil. All other subsoil horizons were deficient in available P, and maximum yields occurred only when both N and P were added. Fertilized subsoils producing more dry matter yield than their respective surface soils were: Colby AC, Cca, and C; Weld B3ca, Cca, and C; and the Rago B21, A1b, B2bca, B3bca, and C. Fertilized subsoils producing yields similar to their surface soils were: Weld B22; Rago A‐B; and the Keith A1b, B2b, B3bca, Cbca, and C. The remaining fertilized subsoils (Weld B21 and Keith B2 and B2ca) produced less yield than their respective surface soils.
Morphology of Soils With Fragipans in Parts of Wilson County, North Carolina
Authors: Daniels R. B. , Nettleton W. D. , McCracken R. J. , Gamble E. E.
Published: July 2010

Moderately well to very poorly drained soils in parts of the North Carolina Coastal Plain have subsurface horizons with the physical properties of fragipans. The brittle parts of the fragipan horizons are dense gray loamy sands, sandy loams or silt loams. This dense brittle material occurs in the same horizon with less dense, friable, more clayey materials.

Soils with weakly expressed fragipan horizons have an A, Bt, Bt & A′2x, B′tx, and C horizon sequence. Soils with the most strongly expressed fragipan horizons have an A, B, A′2x, B′tx, and C or an A, A2x, Btx, and C horizon sequence. The fragipan horizon in the most strongly expressed pans in places engulfs the overlying B horizon.
Phosphorus Uptake in Young Pitch Pine (Pinus rigida Mill.)
Authors: Voigt G. K.
Published: July 2010

Phosphorus sorbed by young pitch pines was related to water‐soluble P, P extracted by 0.002 n H2SO4, by HOAc‐NaOAc or by NH4F‐HCl in the rooting zones of these trees. Average annual P requirements were approximated by the three acid‐extracting agents but water‐soluble P in the root surface zone was considerably less than the annual uptake. Mean P concentration of the soil solution immediately adjacent to the root surface was estimated to be about 0.5 ppm. There appeared to be an interaction between P and Ca which resulted in reduced P uptake with increasing Ca concentration. Increased sorption of both P and Ca was associated with increased root surface. The results suggest that apatite or apatite‐like compounds may have served as a source of P but attempts to verify presence of apatite in the soil were inconclusive.
A Method for Visualizing the Flow of Solutions Through Porous Media
Authors: Knoll K. C. , Hajek B. F.
Published: July 2010

Grouting agents which bind particles together were used to demonstrate the flow of solutions through porous media. The grout was infiltered into a soil‐sand fraction, beach sand and spherical glass beads. The solidified masses showed the irregular wetted volume of sand media and the uniform glass bead wetted volume.
Soil Moisture Transport Due to Thermal Gradients: Practical Aspects
Authors: Cary J. W.
Published: July 2010

The present status of knowledge concerning thermally induced transport of moisture in soil is reviewed. This includes the various theories on mechanisms of transport and experimental data showing the magnitude of moisture flow in various porous materials. Wherever possible these data were chosen to show the relative importance of thermal versus head‐type flow and some general trends are noted.

Simple equations are developed to describe the thermally induced moisture flow near the soil surface which arises from transient thermal gradients produced by the diurnal temperature cycle. Calculations of the moisture flux over 2 ten‐hour time intervals for a typical field situation indicate that thermal water transport should be considered whenever moisture, salt, or heat fluxes are being studied in the soil's surface layers.

The upward flow of soil water against a moisture content gradient in the winter is also considered. A sample calculation of the amount of thermally driven moisture was made using data available in the literature. The result suggested that the thermal moisture flow was too small to account for the net movement of soil moisture into the frost zone.
Effect of Soil Humic Acids on Uptake of Fission Products by Excised Roots
Authors: Tatsukawa Ryo , Franklin R. E.
Published: July 2010

Two‐phase membrane equilibrium systems were used to study complexing of humic acids with fission products and the effect of complexing on the uptake of fission products by excised roots. Humic acids from Rifle peat and an Alaskan peat were purified by centrifugation and resin column treatment. Higher concentrations and greater uptake of the fission products Fe59, Sr90, Ru106, and Cs137 from the Rifle peat humic acid suspensions than from equilibrium dialyzates indicated some form of complexing of the isotopes with the organic matter. The humic acid from the Alaskan peat exhibited very little suspension effect as measured by uptake. The degrees of complexing by the humic acid according to distribution of isotopes in the systems were in the order Fe ≫ Sr > Cs > I. Total uptake and the availability to plants of complexed isotopes tended to be in the reverse order.
The High‐salt‐water Dilution Method for Reclaiming Sodic Soils
Authors: Reeve R. C. , Doering E. J.
Published: July 2010

As a sodic soil is leached with successive dilutions of a divalent cation‐containing high‐salt water, exchangeable sodium is replaced by divalent cations from the leaching solution in accordance with the “valence dilution” principle. Water intake is maintained by the flocculating effect of the electrolyte in the water. Equations are derived that describe the equilibrium exchangeable‐sodium‐fraction of the soil and the depth of water required to effect reclamation in terms of measurable properties of the soil, and the chemical composition of the water. The suitability of a particular water for reclaiming a given soil and the depth of water required can thus be evaluated. The case of constant‐rate dilution is also considered and depth of water equations are written in terms of a dilution‐rate parameter B. The depth of water required to effect reclamation depends upon the ratio R of the divalent cations to the total cations in the available high‐salt water, the total salt concentration of the water, and the dilution rate. The strongest dependence is upon R, with the amount of water required for reclamation decreasing markedly as R increases.
Response of Slash Pine (Pinus elliottii Engelm. var. elliottii) to Phosphorus in Sandy Soils
Authors: Pritchett W. L. , Llewellyn W. R.
Published: July 2010

Rock phosphate or superphosphate band applied to slash pine about 1 year after transplanting resulted in significant height and diameter increases in 5 of 8 experiments, 3 to 5 years after treatment. However, response occurred only on somewhat poorly to poorly drained (flatwood) sands of the Groundwater Podzol and Humic Gley groups. While 50 lb N/acre applied alone usually suppressed tree growth, when applied in combination with 35 lb P/acre, it resulted in additional response. After the third year, 140 lb P/acre from rock phosphate gave about as good results as 35 lb P/acre from superphosphate. The optimum level of tissue P in current needles of 3‐ to 5‐year‐old trees was approximately 0.10%. Total soil P did not appear to be of much value for predicting response of young pine trees to added P. However, the amount of P extracted from unfertilized surface soil with 1.0N NH4OAc (pH 4.8) was negatively correlated with response to phosphate applications on flatwoods sands. Curvilinear regression lines in relation to tree response to varying levels of fertilizer P with amounts of soil extractable P were constructed.
Diffusion of Salts in Clay‐Water Systems
Authors: Kemper W. D. , van Schaik J. C.
Published: July 2010

Rates of salt diffusion through homoionic clay plugs were determined after the plugs had been brought to steady state between solutions of the chloride of the cation with which the clay was saturated. Salt and water contents were measured across the clay plugs and were used with the diffusion rates to calculate porous system diffusion coefficients.

Diffusion coefficients increased as an exponential function of water content, but for practical purposes, were independent of the salt concentration.

Diffusion potentials were measured and calculated. They indicate that the adsorbed cations contribute slightly to the movement of the salt cations.
A Modified Chang and Jackson Procedure for Routine Fractionation of Inorganic Soil Phosphates
Authors: Petersen G. W. , Corey R. B.
Published: July 2010

A method is described for the routine fractionation of inorganic soil phosphates. Use of constant suction pipettes, two molybdophosphoric reductants with different sensitivities, and an isobutyl alcohol extraction for the determination of reductant soluble phosphates greatly increased the speed of the phosphorus determinations. Results from 100 deplicated soil samples had average coefficients of variation and correlation between duplicates within samples for the four phosphate fractions of 3.7% and 0.998, respectively.
The Free Energy of Formation of Gibbsite and Al(OH)4‐ from Solubility Measurements
Authors: Kittrick J. A.
Published: July 2010

Solubility determinations on two particle sizes of crystalline gibbsite, from both undersaturation and supersaturation in the acid pH range, gave a KSO of −34.03 ± 0.05. Using the same gibbsite in the alkaline pH range and extrapolating values from supersaturation to infinite time, a *KS4 of −15.30 ± 0.05 was obtained. From these values a ΔGf0 (gibbsite) of −274.20 ± 0.06 kcal/mole of Al(OH)3 and a ΔGf0 [Al(OH)4‐ aq] of −310.03 ± 0.07 kcal/mole were calculated. The value for gibbsite confirms previous work on the stability of gibbsite and the new Al(OH)4‐ value eliminates a discrepancy between gibbsite stabilities derived from solubility measurements in the acid and in the alkaline pH range.
Effective Volume of Soil Around Plant Roots Determined from Phosphorus Diffusion
Authors: Olsen S. R. , Watanabe F. S.
Published: July 2010

The effective volume of soil contributing P to the roots was measured from a knowledge of the diffusion coefficient of P, a capacity factor for renewal of the soil solution, and the P concentration in solution. Rate of P uptake per square centimeter of surface area by excised corn roots was measured from P32‐tagged soils at ⅓‐bar moisture suction. The rates of release of resin‐extractable P from the soils were determined. These rates of release of extractable P from the effective volume of soil were much greater than the rate of uptake by the roots. The data indicate strongly that the rate of release of solid phase soil P to the soil solution is a nonlimiting step in the absorption mechanism of P by roots.
Nitrosation of Soil Organic Matter: II. Gas Chromatographic Separation of Gaseous Products
Authors: Stevenson F. J. , Harrison R. M.
Published: July 2010

Gas chromatographic techniques were developed for separating and determining inorganic gases in experimental systems dealing with losses of soil N. A single column, consisting of acid‐washed chromatographic‐grade coconut charcoal, gave excellent resolution of H2, N2, CO, CO2, N2O, and NO (or O2). The sensitivity of the method for NO and CO was improved considerably by blocking sorption sites responsible for irreversible retention of these gases. Alkyl nitrites did not interfere with the separations.
Soil Chemical Changes and Infiltration Rate Reduction Under Sewage Spreading
Authors: Thomas Richard E. , Schwartz Warren A. , Bendixen Thomas W.
Published: July 2010

Laboratory and field lysimeters were used to investigate the site and nature of soil‐pore clogging under sewage spreading. The site of clogging was located by determining with a seepage meter the impedance profile at 0.5‐cm depth intervals. Soil samples were analyzed for sulfide, iron, phosphate, total organic matter, polysaccharide, and polyuronide to evaluate possible causative relationships. The infiltration rate loss exhibited three phases: phase I, a slow reduction under aerobic conditions; phase II, a rapid reduction under anaerobic conditions; and phase III, a further gradual decline under anaerobic conditions. The primary site of clogging was the 0‐ to 1‐cm depth of soil. Although sulfide was an indicator of anaerobic conditions, it was not a primary cause of clogging. Accumulations of the other five measured constituents may contribute to clogging in both phase I and phase II. Organic matter was the only probable clogging agent to decline as the infiltration rate was partially recovered in a rest cycle.
Phase Composition of Frozen Montmorillonite‐Water Mixtures from Heat Capacity Measurements
Authors: Anderson Duwayne M.
Published: July 2010

Equations are written that form the basis of a method for determining the unfrozen water content of frozen clay‐water mixtures from heat capacity measurements. The heat capacity of frozen sodium‐montmorillonite water mixtures was determined at −4.7 and −9.6C with a Calve. Microcalorimeter. The data were then used in conjunction with the method described to obtain the unfrozen water content of these clay wate mixtures. The data obtained indicate that the method is applicable at temperatures below about −5C. The amount of unfrozen water found in the frozen clay‐water mixtures at −5 to −10C is quivalent to an interfacial surface layer of water of from one to two molecular diameters in thickness. Most of this water can be accommodated and is though to be located in interlamellar regions.
Effect of Shear on Suction in Saturated Clays
Authors: Day P. R. , Ripple C. D.
Published: July 2010

A slurry of clay and water that has remained undisturbed for several days undergoes a rapid lowering of suction when sheared. After shear has ceased the suction increases spontaneously towards the original value at an exponential rate. These effects have been observed in various clay types and in bentonite with various cation treatments.

Deformation generally has a strong influence on the suction, whose changes with shear depend upon the preconsolidation or prestress history of the soil. Shearing a clay through an angle of only 2° or 3° may affect its suction markedly.

The effect is similar to, and is associated with, the phenomenon of thixotropy. The present measurements furnish support for the theory that shear causes rupture or displacement of the structural bonds of clay‐water systems and, perhaps more significantly, that the structures tend to reform spontaneously.
The Effect of Carbon Dioxide on the Chemisorption of Ammonia by Base‐saturated Clays
Authors: du Plessis M. C. F. , Kroontje Wybe
Published: July 2010

The presence of CO2 increased and stabilized the effective retention of ammonia, applied as aqua ammonia, by base‐saturated clays. Ca2+‐ and Mg2+‐bentonites particularly showed a striking increase in the retention of ammonia in the presence of CO2.

It is postulated that the Ca2+ and Mg2+ exchanged by ammonia, are precipitated as highly insoluble compounds thus stabilizing the retention of chemisorbed ammonia.
Decomposition of Carbon‐14 Labeled Atrazine in Soil Samples from Sanborn Field
Authors: Wagner G. H. , Chahal K. S.
Published: July 2010

Soil samples from corn (Zea mays) and from timothy (Phleum pratense) plots of Sanborn Field, with and without glucose added, were incubated for 6 months after treating with 10 ppm of C14 ring‐labeled atrazine. During the incubation period, < 2% of the ring carbon of atrazine was evolved as CO2 from the glucoseamended soils and < 1% from the unamended soils. The rate of C14O2 evolution from the corn soil did not vary greatly throughout the incubation, whereas, for the timothy soil it peaked at 1 week and then rapidly declined. Evolution of CO2 from glucose and native organic matter was not influenced by the atrazine treatment. Recovery of unchanged atrazine after concluding the incubation averaged about 10% of that initially added. The bulk of the added C14 was not extracted in the course of making these measurements but its persistence in the soil was confirmed by total combustion.
Copper and Molybdenum Nutrition of Crops Grown on Acid Sphagnum Peat Soil
Authors: MacKay D. C. , Chipman E. W. , Gupta U. C.
Published: July 2010

Five crops, carrot, onion, spinach, cauliflower and lettuce (Daucus carota L., var. sativa D. C.), (Allium cepa L.), (Spinacia oleracea L.), (Brassica oleracea, var. botrytis L.), (Lactuca sativa, var. capitata L.).] were grown successively in pails of virgin sphagnum peat soil receiving 6 rates of Cu and 5 of Mo in a replicated factorial experiment. The soil was limed to slightly above pH 5.0 and other nutrients were added as necessary.

Significant yield responses to Cu applications were obtained with all crops, because of deficiencies on the untreatnts. soil and of toxicities on the plots receiving very high treatments. Molybdenum treatments also encompassed the range from deficiency to toxicity with all crops except spinach.

Except for Cu in onion, analyses for Cu and Mo in aboveground plant tissue after harvests were closely related to treatments. The range in Mo content was 0.2–7, 0.4–42, 0.3–140, 1.8–1,140, and 0.5–280 ppm. for carrot, onion, spinach, cauliflower and lettuce, respectively. The range in Cu content for the same crops was 3.4–14, 6.5–11, 1.6–64, 2.2–17, and 3.1–13 ppm.

A mutual antagonism between Cu and Mo was appaarent whereby the application of one element to the soil significantly affected the content of the other in the plant (except for onion). This was related to a significant yield interaction with cauliflower and to nonsignificant trends with the other crops. In general, the antagonism was exemplified in one or both of the following ways: (i) Toxicities of one nutrient were alleviated by applications of the other; and (ii) deficiencies of one nutrient were aggravated by excesses of the other.
Cambic and Certain Noncambic Horizons in Desert Soils of Southern New Mexico
Authors: Gile Leland H.
Published: July 2010

In a study area of southern New Mexico, horizons in the B position may be ordered in degrees of increasing development, and form an essentially continuous series closely related to age. No evidence of soil development is found in freshly deposited arroyo alluvium. Next in the developmental scale are horizons with some weak evidence of soil formation, but which are still too weakly developed to qualify as cambic horizons. With increasing age, cambic horizons and finally argillic horizons occur in the B position. The relationships of soil development to age are confounded in some older soils by such factors as soils truncation and soil mixing.

Distinct cambic horizons have formed in soils that are less than about 5,000 years old. In various cambic horizons there has been sufficient alteration of the original parent material to destroy fine strata, form structure, develop redder color, redistribute carbonate, and accumulate slight amounts of silicate clay. Cambic horizons of old, polygenetic soils show evidence of profound change in the B position since deposition of the parent materials and the start of soil formation. Argillic horizons apparently formed in some soils and were later destroyed. Some soils once had much thicker B horizons than they now have.

The present climate of this desert region is arid, but evidence of former glaciation and lakes indicates a climatic change. The present climate is apparently warmer and drier than the climates of Pleistocene pluvials. Soils formed mainly in the Pleistocene tend to have thicker, stronger horizons than do soils formed in the Recent; this is apparently caused in part by the Pleistocene pluvial climates.
Strength of Compacted Amarillo Fine Sandy Loam as Influenced by Moisture, Clay Content, and Exchangeable Cation
Authors: Mathers A. C. , Lotspeich F. B. , Laase G. R. , Wilson G. C.
Published: July 2010

Unconfined compression strength of Amarillo fine sandy loam was affected by water content (at molding and at time of strength test) bulk density, clay content, and saturating cation. When dried after molding, briquettes of Amarillo fine sandy loam attained maximum strength at 3 to 6% water depending on clay content. Maximum strength was attained at approximately one monolayer of water on the total surface area suggesting that H‐bonding of water molecules contibutes to soil strength. As additional water was lost, strength decreased to a minimum at onehalf monolayer and increased again as complete dryness was approached. Shapes of the drying curves were similar regardless of the percent molding water, bulk density, clay content, or exchangeable cations.

Na‐saturated soils had greater dry strength than Ca‐ or Al‐saturated soils.
The Occurrence of High Molecular Weight Organic Phosphorus Compounds in Soil
Authors: Thomas R. L. , Bowman B. T.
Published: July 2010

An extraction procedure using the chelating resin Dowex A‐1 after an HF‐HCl pretreatment is described for the extraction of high molecular weight organic phosphorus compounds. This procedure appears to reduce the degradation of high molecular weight compounds that occur with more drastic extraction techniques now in use
Soluble Silica in Soil
Authors: Miller Raymond W.
Published: July 2010

Silica, as dissolved Na2SiO3, was added to soil samples or to soil cores; the silica was measured as the molybdenum blue complex of mono‐ and disilicic acid. The concentration of silica in a soil solution is determined by the soil's properties. Solubility is both temperature and pH sensitive. When large quantities are added to soil as a solution of NaSiO3 and then dried, only a smaller concentration of soluble silica characteristic of the soil will remain in simple soluble forms. The fate of the bulk of the added silica is believed to be some reaction with disorganized or amorphous surfaces of silicate particles in the soil. This alteration of soluble silica is rapid and results in a lower silica concentration in the soil extract than would be expected if no reaction occurred. The change in concentration of soluble silica can occur in the time required for water to percolate through the soil profile. The change can also occur either during drying or while the soil is maintained in a moist condition.

Addition of CaCO3 to soil reduced the “equilibrium” silica concentration of a soil extract. This is believed to result mostly because of a change in pH of the soil. Higher temperatures increased the concentration of soluble silica obtained.

The presence of soil pans containing cementation by silica might be at least partly explained by changes in pH of profile layers, temperature alterations with depth, and loss of water by soil dehydration. Aging and drying would aid the development of deposits of a nonreversible nature.
Humification of Carbon‐14 Labeled Glucose in Soils of Sanborn Field
Authors: Mutatker V. K. , Wagner G. H.
Published: July 2010

Duing the incubation of C14‐labeled glucose in soil for 3 months, 25% of the radioactive carbon was incorporated in the soil organic matter while the remainder was evolved as CO2. Fellowing incubation, the soil organic matter was extracted by 0.5N NaOH and fractionated. Humin, humic, and fulvic fractions were similarly labeled in a given soil. Generally, soil organic matter resulting from glucose was rather uniform in character for the several soils studied, whereas, that present prior to adding glucose may have differed among soils as a result of humification of diverse substrates. Selective combustion of aliphatic material in each fraction by heating at 170C for 25 days indicated that about 50% of the total carbon in humin and fulvic material and 66% of that in humic acid were aromatic. Aromatic and aliphatic components of the fulvic fraction were about equally labeled in all soils. Humic acid and humin showed less C14 incorporation into the aromatic than the aliphatic component.
Confounding the Triple Cube Response Surface Design to Reduce Block Size
Authors: Stavrou J. , Cady F. B.
Published: July 2010

Modification of the composite response surface designs, called cube designs, have been effected by experimenters but result in large block size. Procedures are given for block size reduction. The confounding procedure is shown for the triple cube and the resulting analysis of variance structure and inverse matrix are given.
A Rapid Citrate‐Dithionite Extractable Iron Procedure
Authors: Holmgren George G. S.
Published: July 2010

A procedure for obtaining iron which is both convenient and reliable is described. The procedure involves shaking the samples overnight in a citrate‐dithionite buffer. This is followed by a colorimetric iron determination using orthophenanthroline. The use of an automatic pipette, a flocculating agent, and noncritical quantities of dry reagents facilitates the determination. The results show increased effectiveness and reliability over Kilmer's porcedure for high‐iron Oxisols and Ultisols from Puerto Rico.
Potassium Nutrition Effects on Net Photosynthesis and Morphology of Alfalfa
Authors: Cooper R. B. , Blaser R. E. , Brown R. H.
Published: July 2010

Greenhouse experiments were conducted to study the influence of K on CO2 assimilation, growth, and morphological characteristics of alfalfa (Medicago sativa L.). Yield increases were consistently obtained with high K. Added K increased plant height. The rate of leaf accumulation, leaf size, and weight per unit area also increased as did stomatal number and aperture. More and larger epidermal cells per leaf were observed with high K nutrition. Net photosynthesis rates of excised leaves increased with K application. Leaves from plants with added K had lower CO2 compensation points, indicating higher efficiency of CO2 assimilation under limiting CO2 conditions.
Sampling for Pedographic Modal Analysis of an Argillic Horizon
Authors: Milfred C. J. , Hole F. D. , Torrie J. H.
Published: July 2010

Pedographic modal analysis expresses soil composition in terms of the relative amounts of constituents observed in thin sections. Data are presented on the sampling density necessary for pedographic modal analysis of an argillic horizon. Thirty‐one randomly selected samples (100cc cores) were obtained from a 61 cm by 61 cm vertical exposure of the horizon. Four thin sections were made from each core. Six constituents were counted in each thin section by the point count method of modal analysis. Constituents less than 50 µ in diameter were classified as matrix, while those larger than 50 µ were classified as glaebules, pores, papules, argillans, or skeleton grains.

Results indicate that a sample adequate to measure these constituents in an argillic horizon with a standard error 10% of the mean would involve taking 21 cores, making 2 thin sections per core, and counting 1,000 points per thin section.
Determination and Isotope‐Ratio Analysis of Different Forms of Nitrogen in Soils: 7. Urea
Authors: Keeney D. R. , Bremner J. M.
Published: July 2010

Two methods of determining urea in soils are described. In one (extraction‐distillation method), the soil sample is extracted with 2M KCl (10 ml/g of soil) for 5 min, and an aliquot of the extract is treated with potassium phosphate buffer (pH 8.0) and urease for 2 hours at 30C to convert urea N to ammonium N. In the other (direct‐distillation method), the soil sample is treated directly with pH 8.0 potassium phosphate buffer and urease for 1 hour at 30C. In both, the ammonium released by the urease treatment is separated by steam distillation of the treated sample for 3.3 min and determined by titration of the distillate with standard acid. The extraction‐distillation method is useful when analyses for nitrate and nitrite as well as urea are required, but it does not give completely quantitative recovery of urea added to some soils. The methods are rapid, specific and precise, and they permit isotope‐ratio analysis of urea N in N15‐tracer studies of urea transformations in soils.
Salt Displacement and Titration of AlCl3‐Treated Trioctahedral Vermiculites
Authors: Kaddah Malek T. , Coleman N. T.
Published: July 2010

Freshly prepared and 45‐day‐aged Al‐saturated trioctahedral vermiculites from Libby, Montana, and northeastern Transvaal, South Africa, were: (i) leached with 1N and 0.05N solutions of NaCl, KCl, and CaCl2, (ii) subjected to repeated cycles of 1N NaCl leaching and Al saturation, and (iii) potentiometrically titrated in H2O or N NaCl. In the leaching experiments, the exchange acidity, exchangeable H, Al, and Mg, and the CEC after leaching were determined.

Salt solutions displaced only part of the adsorbed Al, with less from South African than from Libby samples. Also displaced were H3O and small amounts of Mg ions. The exchange acidity (H3O + Al), the ratio of H3O to Al, the displaced Mg, and the apparent CEC after Al saturation and displacement varied with the kind and concentration of the displacing solution, the source of vermiculite, the aging period, and the number of cycles of Al saturation and displacement.

With freshly prepared Libby samples, the exchange acidity varied from about 60 to 80% of the CEC, with Al constituting 60 to 90%. The corresponding ranges for South African samples were 35 to 50% and 30 to 85%. Of the three salts, KCl solutions gave the smallest exchange acidity and the lowest values for Al/exchange acidity; CaCl2 effected the highest values, with NaCl in between. Dilution of displacing solutions generally increased the H3O ion component of exchange actidity. Repeated Al saturation and displacement resulted in decreased exchange acidity.

Potentiometric titration curves of Al‐vermiculites in H2O did not suggest the presence of appreciable amounts of exchangeable H3O. Titration curves in NaCl had buffer ranges interpreted as suggesting the presence of H3O, Al, and another component presumed to be mostly monohydroxy‐Al ions.

The two Al‐vermiculites manifested by X‐ray analysis different collapsibility on K saturation and heat treatment. The X‐ray data support the conclusion that Al hydrolysis occurs between vermiculite plates, with general correspondence between the amount of nonexchangeable Al and the failure of the minerals to collapse to 10A upon K saturation and drying.
Desorption of Phosphate from Kaolinite
Authors: Kafkafi U. , Posner A. M. , Quirk J. P.
Published: July 2010

Initially all the phosphate adsorbed onto kaolinite is isotopically exchangeable. On washing some of the phosphate ceases to be exchangeable, but if the amount that remains labile is plotted against the solution concentration the original isotherm is preserved. Thus, some of the total phosphate goes into a nonexchangeable “fixed” sink.

If phosphate is adsorbed in very small increments some of it is converted directly into the fixed form. In the presence of large concentrations of phosphate, all the adsorbed phosphate becomes exchangeable.
Soil Temperature Patterns in Surface‐Insulated Containers in Water Baths Related to Maize Behavior
Authors: Walker John M.
Published: July 2010

Different soil surface insulators did not establish isothermal conditions in soil in metal containers placed in constant temperature water baths. The water temperatures were 15, 25, and 35C, with the air temperature about 25C. The behavior of maize (Zea mays L.) seedlings, which were grown in these soils, was related to the degree of temperature control by the various insulators. Differences in growth and ion uptake were statistically significant when the water bath temperatures were not optimum at 15 and 35C.
Contributions of Fixed Charge and Mobile Complexing Agents to the Diffusion of Zinc
Authors: Hodgson J. F. , Lindsay W. L. , Kemper W. D.
Published: July 2010

Zinc was allowed to diffuse from a ZnCO3 precipitate through an agar‐agar gel to a stream of continuously flowing water. In one treatment, part of the agar‐agar was replaced by Ca‐poly‐galacturonate to incorporate fixed negative charges in the gel in the form of carboxyl groups. In a second treatment, Cacitrate was introduced into the flowing stream of water. In every case, all phases of the system were kept in equilibrium with CaCO3.

Both fixed charges and the mobile complexing agent increased the transport of Zn in the system, but the latter was considerably more effective than the former. One percent polygalacturonic acid increased the transport of Zn by 13%, whereas 2 × 10‐3 M citrate increased the transport of Zn 100‐fold.

Results compare favorably with a theoretical treatment for the contribution of the mobile complexing agents to Zn transport.
Ant (Formica cinerea) Pedoturbation in a Prairie Soil
Authors: Baxter F. Paul , Hole Francis D.
Published: July 2010

Active and recently active mounds made by the ant (Formica cinerea montana Emery) number 1,531 ha and occupy 1.7% of the area of the surface of Tama silt loam in a prairie remnant in southwestern Wisconsin. The average volume of an ant mound is 0.02 m3, of which about 12% is occupied by channels and chambers. The mineral soil in the upper half to two‐thirds of a representative mound consists about 85% of B horizon material, judging by soil color, content of clay, and oriented argillans. Unusually high contents of available K and P in the mound are probably a result of concentration by the ants of organic materials, particularly those derived from plant sap from aphids; of rapid mineralization of organic matter; and by addition by the ants of B horizon material. Upward movement of soil material by ants could account for the relatively high clay content of the A horizon of Tama silt loam in southwestern Wisconsin, as contrasted with that of the A horizon of the comparable nearby forest soil.
The Movement of Phytic Acid in Soil Cores
Authors: Bowman B. T. , Thomas R. L. , Elrick D. E.
Published: July 2010

The movement of phytic acid‐phosphorus in a vertical soil core was studied under controlled conditions using a miscible displacement technique. Experiments were conducted on a sandy loam soil with gamma irradiation at 20C and without irradiation at 5C and 20C. Phytic acid appeared to be quickly bound by the soil, accumulating near the top of the soil core. Phytic acid apparently displaced native inorganic phosphorus. The movement of phytic acid increased and its rate of mineralization decreased at 5C as compared to 20C. Gamma irradiation reduced, but did not completely eliminate, mineralization of phytic acid at 20C. Changes in free iron concentration within the core were noted and related to the movement of phytic acid‐phosphorus.
Gamma Irradiation and the Microbial Population of Soils at Two Water Contents
Authors: Jackson N. E. , Corey John C. , Frederick L. R. , Picken J. C.
Published: July 2010

Thirty‐gram soil samples, in plastic tissue culture dishes (60 × 15 mm), were irradiated with gamma rays (8000 curie Co‐60 source) at doses ranging from 0 to 3 million rads. Fungal and bacterial plus actinomycetal counts were made by plating soil suspensions on rose bengal‐streptomycin agar and egg albumin agar, respectively. Plates were incubated for 4 to 8 days before counting. The numbers of fungal and bacterial units reflected differences in survival among the microbial populations from soil samples taken at three horizons within field profiles. Microbial counts in the soils at 30% water content (by weight) were generally reduced to zero at lower radiation doses than those in the air‐dry soils. One million rads were required to kill all fungi, but 2 to 3 million rads were required to kill all bacteria in a 30‐g soil sample. At a given water content, samples with the higher initial microbial populations required greater radiation doses for sterilization than samples with lower populations. For small soil samples, exposure to gamma radiation proved a rapid and efficient method of sterilization.
Responses of the Soil Microflora to Volatile Components in Plant Residues
Authors: Menzies J. D. , Gilbert R. G.
Published: July 2010

Exposure of soil to volatile substances from alfalfa (Medicago sativa L.) hay, corn (Zea mays L.) leaves, and other plant residues induces an immediate rise in the respiration rate of the soil microflora. This if followed by an increase in bacteria numbers and by vegetative growth of fungus mycelia over the soil surface. These volatiles, active at a distance from the plant residue, may function as respiratory and growth stimulants for soil microorganisms in the initial stages of colonization of residue.
Plow‐Layer Porosity and Surface Roughness from Tillage as Affected by Initial Porosity and Soil Moisture at Tillage Time
Authors: Allmaras R. R. , Burwell R. E. , Holt R. F.
Published: July 2010

Total porosity increase and random roughness due to plowing were each significantly affected by the moisture content at tillage time. Their magnitudes were greatest at low moisture contents, decreased approximately linearly as soil moisture increased to the lower plastic limit (LPL), and then increased at moisture contents greater than LPL. The porosity before plowing more significantly affected tillage‐induced random roughness than total porosity increase. There were significant deviations from these generalities within each of the three soil associations: Barnes‐Aastad, Kranzburg‐Poinsett, and Nicollet‐Webster.

In all three associations, the porosity decrease by subsqeuent disking and harrowing was more pronounced where plowing gave the greatest porosity increase. Only in the Kranzburg‐Poinsett association (high in silt content) were porosity increases observed from disking and harrowing near and above the LPL. Disking and harrowing nearly always reduced random roughness, and the reduction increased linearly as the random roughness of the plow treatment increased.