bluuebunny/crossref_metadata_2025 huggingface dataset:
A Soil Test for Phosphorus Based Upon Fractionation of Soil Phosphorus: II. Development of the Soil Test
Authors: Al‐Abbas A. H. , Barber S. A.
Published: July 2010

The correlation of soil P fractions with P uptake by millet was used as a basis for developing a soil test. The soil test consists of shaking 1 g. of soil with 20 ml. of solution made up from 17 ml. of 0.3N NaOH and 3 ml. of 0.5N Na2C2O4. The shaking time had little effect on the amount extracted. The soil test works particularly well on soils of pH above 7.
The Effect of Some Chemical Environmental Factors on Cotton Root Behavior
Authors: Rios M. A. , Pearson R. W.
Published: July 2010

A vertical split‐root technique is described that permitted the measurement of effects of various ions in the subsurface zone on root development. The surface zone consisted of an adequately limed and fertilized sandy loam soil. Cotton roots failed to develop in the lower zone in the absence of Ca, showing that cotton was unable to translocate Ca downward at a rate that would sustain root growth. Development of cotton roots was not prevented by the absence of P in the rooting medium, showing that the translocation rate of P was adequate to supply these roots from surface soil sources. Concentrations of soluble Al as low as 1 ppm. prevented root growth of cotton seedlings and concentrations of 0.5 ppm. greatly reduced root development and caused severe symptoms of toxicity. Even when roots were severely damaged no effects were observed in the tops. Damage to the subsurface roots by Al was not prevented either by liming and fertilization of the surface soil, or by the presence of adequate Ca in the rooting medium itself. High concentrations of Mn did not affect root growth directly.
Soil Viscoelasticity: Superposition Tests
Authors: Waldron Lawrence J.
Published: July 2010

Viscoelasticity is a linear deformation theory in which time‐dependence of stress‐strain ratios conforms to the Boltzmann superposition principle. Three types of superposition tests were made on briquets of Yolo silt loam subjected to torsional deformation. The principle was found to be valid when stress, stress duration, and soil water content were kept below certain limits. Deviation from linear behavior as these limits were exceeded first appeared as non‐Newtonian flow rather than as non‐Hookean (instantaneous) elastic response. Where the principle applies, there is a structural stability under deformation which makes viscoelasticity promising for relating mechanical behavior to soil‐water structure.
The Influence of Soil Temperature and Phosphorus Fertilizers of Different Water‐Solubilities on the Yield and Phosphorus Uptake by Oats
Authors: Case V. W. , Brady N. C. , Lathwell D. J.
Published: July 2010

The effect of root zone temperatures of 15°, 20°, and 25°C. and P sources having water‐solubilities of 1, 25, 50, and 100% were evaluated in two greenhouse experiments using oats as a test crop. Oats were grown for 43 days and height, dry weight, and P uptake were determined.

Height response to added P was greatest at 15°C. and least at 25°C. The effects of temperature on height were greatest where no P was applied. There was a marked response in forage yields and in P uptake to increasing amounts of applied P and to increasing soil temperature. Root yields and P uptake, however, were highest at 15°C. and lowest at 25°C. In both tops and roots the temperature effect was greater at high rates of P than at low rates of P application.

In the winter experiment using ammoniated superphosphates, yields and P uptake by oat forage decreased as the percentage of water‐soluble P decreased, except at the lowest percentage of water‐soluble P where yield and P uptake were not related to water‐solubility of P. In the fall experiment where mixtures of MCP and DCP were used, the source of P had little effect on yield and P uptake.
Carbonate Clay: Measurement and Relationship to Clay Distribution and Cation‐Exchange Capacity
Authors: Shields L. G. , Meyer M. W.
Published: July 2010

A method for the determination of carbonate clay as an integral part of the pipette method for particle‐size analysis is given. Carbonate clay is calculated by measuring the gravimetric loss of CO2 from a 50‐ml. aliquot of the clay (< 2µ) fraction.

For some calcareous soil materials a substantial proportion of the clay fraction consists of carbonate. A survey is given of the proportion of carbonate that is claysize. Five kinds of clay percentages for calcareous soil materials are discussed. The application of carbonate clay data to the interpretations of clay distribution curves is presented.

Evidence is presented that carbonate, including carbonate clay, has negligible cation‐exchange capacity. The effect of the presence of carbonate clay on the calculated cation‐exchange capacity of the clay fraction is discussed.
Extraction of Clay‐Water Systems
Authors: Lagerwerff J. V.
Published: July 2010

Experimental data on suspensions of Na‐montmorillonite in solutions of various NaCl concentrations quantitatively confirm existing theory which predicts a gradual decrease in the extract concentration during pressure extraction (salt exclusion). This decrease is preceded by a maximum in extract concentration when salt is retained in the suspension (salt sieving). The theoretical descriptions imply a constant salt‐sieving factor. A coarser filter was found to be associated with stronger salt sieving. The extract from mixed Na‐Ca suspensions in chloride solutions shows an increasing concentration of Na relative to Ca during protracted extraction. Practical implications of the results are discussed.
Effects of Supplemental Irrigation with Saline Water on Soil Composition and on Yields and Cation Content of Forage Crops
Authors: Lunin J. , Gallatin M. H. , Batchelder A. R.
Published: July 2010

Dilutions of synthetic sea water were used for supplemental irrigation on small plots containing alfalfa, Kentucky 31 Fescue, orchardgrass, and ladino clover. One treatment irrigated with nonsaline water and a nonirrigated control were also included. Significant increases in yield due to irrigation were obtained in only a few instances during the second through fourth year of study, but during the first year two of the four cuttings of all four crops responded to supplemental irrigation. Where several irrigations were applied, yields tended to decrease with increasing salinity, with ladino clover being the most sensitive of the four crops tested. Soil salinity increased to ECe values as high as 15.4 mmho. per cm. (electrical conductivity of the saturation extract) as a result of saline irrigation. The Ca, Mg, and K content of all four crops were relatively unaffected by soil salinity. The Na content of all plants tended to increase with increasing salinity, with the greatest accumulation occurring in the ladino clover. Exchangeable Ca decreased and Mg, Na, and K increased with increasing salt concentration of the water applied.
Wheat Stubble Management: I. Influence on Some Physical Properties of a Chernozem Soil
Authors: Ramig Robert E. , Mazurak Andrew P.
Published: July 2010

Four methods of wheat stubble management (burn and plow, plow, one‐way disk, and subsurface‐till) in an alternate wheat‐fallow system on a Chernozem soil were studied for 12 years. Plots were split, with one‐half of each plot receiving N fertilizer. Twelve years of subsurface‐tilling or one‐way disking substantially increased the geometric mean diameter of water‐stable aggregrates and decreased the bulk density of the surface soil as compared with plowing or burning and plowing. The ratio of water entry, 10 minutes to 120 minutes, was substantially lower in wheat plots that had been subsurface‐tilled or plowed than where the plots had been burned and plowed or one‐way disked. Application of N fertilizer did not affect the physical properties measured.
Combining Surface Mulches and Periodic Water Applications for Reclaiming Saline Soils
Authors: Carter David L. , Fanning Carl D.
Published: July 2010

Water applied by periodic sprinkling of surface‐mulched soil resulted in greater salt removal and higher leaching efficiency than did either flooding or periodic sprinkling of bare soil. Cotton (Gossypium hirsutum) bur and chopped shrubbery mulches were about equally effective. Flooding and sprinkling bare soil decreased salt concentration in the surface 2 feet of the soil profile, but salt accumulated below a depth of 3 feet when compared with check soil that received only rainfall. Similarly, salts were removed from all depths to 5 feet where surface mulches were present. The salt leaching efficiency decreased from above 90% in the surface foot to approximately 33% in the fifth foot of surface‐mulched soil. The higher leaching efficiency for mulched soil was attributed to the probably reduced evaporation under mulches that lessened upward movement of water.
Microrelief Influences in a Saline Area of Ancient Glacial Lake Agassiz: II. On Shallow Ground Water
Authors: Benz L. C. , Sandoval F. M. , Mickelson R. H. , George E. J.
Published: July 2010

A study was made of the shallow ground‐water regime in a ridge‐depression microrelief area where high salinity occurred in the ridges compared to low salinity in the depressions. Ground‐water movement was affected by: (a) surface relief, which caused impounding of precipitation in the depressions; (b) greater hydraulic conductivities in the depressions; and (c) differences in moisture use due to greater tree and vegetative growth in the depressions. Water tables fluctuated from above the ground surface to depths of 10 feet. Salt concentrations of ground water were much higher in the ridges than the depressions. These differences occurred to a depth of 20 feet.
Relative Erodibility of Three Loess‐Derived Soils in Southwestern Iowa
Authors: Schmidt B. L. , Shrader W. D. , Moldenhauer W. C.
Published: July 2010

Measurements of original and present surface soil depth, as indicated by slope and erosion field data and organic carbon contents, were used to determine the relative erodibility of the loess‐derived Monona, Marshall, and Sharpsburg soils in southwestern Iowa. These studies indicated decreasing surface soil depths with increasing slope on all three soils, with the Monona soil having the least and Sharpsburg the most surface soil remaining. The difference in average depth to an arbitrary benchmark, 0.90% organic carbon content, in cultivated as compared with virgin profiles of each soil indicated, however, that slightly lower erosion losses due to cultivation over time have occurred on the Monona soil.

Laboratory rainfall simulator studies indicated higher infiltration and lower soil loss rates on the Monona soil than on the Marshall and Sharpsburg soils. The formation of a dense surface seal by raindrop impact appeared to be a dominant factor in the erodibility of these soils. Studies on crusted samples indicated slightly lower soil loss and higher infiltration rates on the Monona even with the crust present.
Heat Capacities of Clay and Clay‐Water Mixtures
Authors: Oster J. D. , Low Philip F.
Published: July 2010

Heat capacities of mixtures of several homoionic clays with different amounts of water were determined with a Bunsen ice calorimeter. The specific heats of the clays were also determined by the same technique. From the results, the apparent specific heats of the water are calculable. In addition, the partial specific heat of the water associated with each clay at each of several water contents was determined by plotting the heat capacity of the mixture against the water content (in grams of water per gram of clay) and taking the slope of the resulting line at the desired water content. In all cases, the apparent specific heat and the partial specific heat of the water were > 1.0 at low water contents (< 1.0 gram water per gram of clay). At higher water contents the values of these quantities approached unity. The results were interpreted in terms of the contribution of H‐bonding to the specific heat of the water.
Competition of NH3 and H2O for Adsorption Sites on Clay Minerals
Authors: James D. W. , Harward M. E.
Published: July 2010

Ammoniation of air‐dry Ca, Mg, and Al montmorillonite and bentonite resulted in dehydration of the exchangeable cations and a change in c‐axis spacing from 15 to 16Å. to 12.6 to 13Å. Ammoniation of a vacuum‐dried Ca system resulted in a change in c‐axis spacing from 10.1 to 12.3Å. On the other hand, NH3 retained by the minerals upon ammoniation was replaced by H2O under controlled conditions of relative humidity. It was postulated that the mutual competition between H2O and NH3 molecules for adsorption sites can be described by the law of mass action. The various theories which have been proposed to describe the mechanism of NH3 chemisorption are discussed.
D2O‐Na24 Method for Tracing Soil Moisture Movement in the Field
Authors: Haskell C. C. , Hawkins R. H.
Published: July 2010

A unique method is described for measuring unsaturated flow of water in the field with D2O tracer, a Na24 gamma source, and a slow‐neutron detector. The interaction of gamma radiation of energy greater than 2.23 Mev. and deuterium produces photoneutrons. The Na24 gamma source and the slow‐neutron detector are contained in a modified neutron‐type soil moisture probe. The method successfully measured vertical movement of deuterium tracer in a Gilead sandy loam with the aid of access tubes.
Water Vapor Diffusion in Relatively Dry Soil: IV. Temperature and Pressure Effects on Sorption Diffusion Coefficients
Authors: Jackson Ray D.
Published: July 2010

The temperature and pressure dependence of water transfer coefficients in two relatively dry soil materials were measured. The relative magnitudes of liquid and vapor transfer were obtained from the pressure experiments. The liquid diffusion coefficient for Adelanto loam was 20 to 40% of the total diffusion coefficient, whereas for Pachappa loam the liquid diffusion coefficient was negligible. The temperature dependence of the vapor diffusion coefficient for Adelanto and the total diffusion coefficient in Pachappa can be calculated from published data on the temperature dependence of the water vapor diffusion coefficient in air and the saturated vapor density. The activation energy for the liquid component in Adelanto was calculated by combining the temperature and pressure diffusion data and was found to be about 4.2 kcal mole‐1 for water contents above a monolayer.
Self‐Diffusion Coefficients of Phosphorus in Soil Measured by Transient and Steady‐State Methods
Authors: Olsen S. R. , Kemper W. D. , Van Schaik J. C.
Published: July 2010

Self‐diffusion coefficients of P in soil were measured by two independent methods and by calculating Dp from chloride diffusion. All three methods yielded similar values for Dp at low moisture suctions. On Apishapa silty clay loam, values of Dp ranged from 0.4 × 10‐7 to 15.5 × 10‐7 cm2/sec as the volumetric moisture content increased from 0.22 to 0.55, or as the soil moisture suction decreased from 6 to < 0.1 bar. From these values of Dp a self‐diffusion coefficient for P in bulk solution was calculated, which agreed closely with the experimentally measured value. The transient state method required a separate evaluation of a capacity factor which varied between 100 to 300. If this capacity factor had been omitted, the apparent Dp would have been smaller by 100‐ to 300‐fold. These results demonstrate the necessity of measuring a capacity factor when Dp is to be determined by a transient state method.
Boron Concentration Adjacent to Fertilizer Granules in Soil, and Its Effect on Root Growth
Authors: Mortvedt J. J. , Osborn G.
Published: July 2010

Rates of dissolution of B from granules of rasorite and three boronated fertilizers in limed Hartsells fine sandy loam decreased in the order: Nitric phosphate (2.2% B) > rasorite (20.2% B) ≫ calcium silicate slag (7.5% B) > calcium metaphosphate (2.1% B). Movement of B from the granules increased with B concentration gradient and soil moisture content.

Concentration of hot water‐soluble B in soil near the granules at a given time depended on: (i) B content of the granule, and (ii) the relative rates of B dissolution from the granule and movement of B from the granule site. Concentrations of B near rasorite granules—as high as 80 parts per million (ppm) in a large volume (4 kg of soil in gallon cans) and 385 ppm in thin soil layers (80 g of soil in Petri dishes)—were inversely proportional to the amount of soil affected.

Root growth of oats and alfalfa was slightly depressed at soil B concentrations of 2 to 5 ppm, and markedly so at concentrations above 10 ppm B. Thus, high concentrations in soil near some B sources may inhibit root growth. Root injury may be prevented by decreasing the B content per fertilizer granule and by applying less soluble sources or lower amounts of B.
Effects of Climatic Factors on Fruit Volume Increase and Leaf Water Deficit of Citrus in Relation to Soil Suction
Authors: Lombard P. B. , Stolzy L. H. , Garber M. J. , Szuszkiewicz T. E.
Published: July 2010

The primary factors affecting the rate of fruit volume increase and leaf water deficit of navel orange trees were investigated under two irrigation treatments. One treatment was applied when tensiometers in the major root zone indicated 20 cbar soil suction and the other treatment was applied at 100 cbar soil suction. The correlations between either fruit volume increase or leaf water deficit and various environmental conditions were studied by factor analysis to determine possible primary factors affecting the water status of the trees. Soil suction, a primary factor in both treatments, influenced the fruit and the leaf in only the 100 cbar treatment. Rate of water movement through the soil to the plant roots could be the underlying factor. Another factor, evaporation power of the atmosphere during high diurnal transpiration affected the rate of fruit volume increase in only the 100 cbar treatment.
Significance of Extractable Aluminum in Hawaiian Sugarcane Soils
Authors: Ayres A. S. , Hagihara H. H. , Stanford G.
Published: July 2010

Aluminum was extracted with water and solutions of NH4OAc, pH 4.8, and KCl from Humic, Hydrol Humic, and Humic Ferruginous Latosols (some of which are considered potential commercial sources of Al) as well as from certain less weathered soils. Exchangeable Al appeared to account for only a small fraction of the Al extracted from some of the more highly weathered soils. NH4OAc‐soluble Al increased markedly with degree of weathering of the soil, but this was not true of KCl‐ or water‐soluble Al. Within each great soil group Al, soluble in all three extractants, increased many times with decreasing soil pH. Concentrations of Al in water extracts did not exceed 2.5 ppm; in soils of pH 5.0 or above, concentrations seldom were in excess of 0.1 ppm. The addition of limestone effectively decreased levels of both NH4OAc‐ and water‐soluble Al. These results, coupled with field observations, have led to the conclusion that Al levels in Hawaiian soils are not sufficiently high to repress the growth of sugarcane.
Phosphorus Fixation as a Transfer Controlled Phenomenon
Authors: Avnimelech Y. , Hagin J.
Published: July 2010

Phosphorus fixation in various soils was accelerated by: (i) the application of P in solution thus inducing its immediate dispersion in the soil, and (ii) increasing the rate of movement of the P in the soil by changes in the water regime. It was concluded that the dispersion of P in the fertilized soil volume is the rate‐limiting step in the process of its fixation and thus P fixation could be described as a transfer‐controlled process.
Response of Table Beets (Beta vulgaris L.) to Banded Fertilizer Phosphorus and Potassium at Different Levels of Soil Phosphorus and Potassium in a Heavily Fertilized Honeoye Silt Loam Soil
Authors: Peck N. H. , Vittum M. T. , MacDonald G. E.
Published: July 2010

Response of table beets to fertilizer P and K banded at planting time in 1960 was determined on a Honeoye silt loam soil which had received various levels of complete fertilizer from 1945 to 1951, and different levels of broadcast fertilizer P and K from 1954 to 1959. Soil P from previously applied fertilizer accumulated to a greater extent and had a longer residual effect than soil K as measured by soil tests; however, responses of beets to different levels of soil K were greater than they were to different levels of soil P. At high levels of soil P, there was little response to differences in soil P or banded fertilizer P. At medium levels of soil K, there were considerable increases in percentage of K in the leaves, plant size, and yield with increases in soil K and/or banded fertilizer K. Responses to different levels of soil P and K, and banded fertilizer P and K were cumulative and generally independent of each other. Generally, the soil P and K were relatively as important as the banded fertilizer P and K in producing high yields of beets.
Forms of Phosphorus in Soil After Long‐Continued Fertilization
Authors: Manning P. B. , Salomon M.
Published: July 2010

The forms of P in a Bridgehampton silt loam (Brown Podzolic) after more than 65 years of phosphate fertilization were studied by the fractionation methods of Chang and Jackson. The investigation showed that superphosphate treatments increased the aluminum phosphate fractions, and iron and calcium phosphate to a lesser degree. Rock phosphate treatments increased the calcium phosphate fraction. Of particular interest was a manured soil where phosphate followed a similar aluminum bonding as did superphosphate.

Occluded and organic phosphate fractions were not greatly affected by various levels and sources of applied phosphate. Summation of the extracted inorganic and organic forms did not equal the total P. This “unextractable” fraction is believed to be tightly bound forms not solubilized by the acid extractions or possibly held as nonexchangeable “lattice” phosphate. There was some indication that lime treatments decreased the amount of aluminum phosphate formed.
The Numerical Analysis of Infiltration, Considering Hysteresis, Into a Vertical Soil Column at Equilibrium Under Gravity
Authors: Whisler F. D. , Klute A.
Published: July 2010

A numerical solution of the flow equation for water in soil was obtained for a flow system consisting of a vertical column of soil which had been drained from saturation to equilibrium with a water table. A thin layer of ponded water was assumed to be applied to the top end of the column. This meant that each point in the column wetted up along a different scanning curve of the moisture characteristic curves. The solution of the equation depicts the time and depth distributions of water content and pressure head during the resulting infiltration. The results show that for soils that have water content‐pressure head curves with regions of steep slopes, the wetting front advances as a steep, well‐defined front. In those soils with more gently sloping water content‐pressure head curves, the wetting front was more diffuse. If hysteresis was ignored, the position of the front at any one time was overestimated or underestimated—depending upon whether the drainage or wetting curve was used.
Determination and Isotope‐Ratio Analysis of Different Forms of Nitrogen in Soils: I. Apparatus and Procedure for Distillation and Determination of Ammonium
Authors: Bremner J. M. , Edwards A. P.
Published: July 2010

Methods of analysis have been developed which permit both determination and isotope‐ratio analysis of inorganic and organic forms of nitrogen in soils and soil extracts. In each method, the form of nitrogen under analysis is converted to, and estimated as, ammonium, which is readily oxidized to nitrogen gas for mass spectrometer assay of N15. The ammonium is separated by steam distillation, collected in boric and acid‐indicator solution, and determined by titration with standard acid. The apparatus and procedure used for distillation and determination of ammonium are described.
Ultrasonic Suspension of Chlorinated Pesticides in Aqueous Media
Authors: Riggs R. L. , Biggar J. W.
Published: July 2010

Ultrasonic energy was employed to produce suspensions of several chlorinated hydrocarbon pesticides in water. The suspensions are homogeneous and the concentrations exceed the known solubilities of the pesticides studied.
Humidity Control for X‐Ray Diffraction
Authors: Anderson James U.
Published: July 2010

The humidity of the atmosphere surrounding samples in the X‐ray diffractometer should be controlled because clay minerals lose or gain water to obtain equilibrium, with resultant changes in basal spacings. A simple apparatus achieves this by supplying air at any desired relative humidity.
A Technique for Making Thin Sections of Soil with Roots in Place
Authors: Lund Z. F. , Beals H. O.
Published: July 2010

A short dehydration series was combined with a plasti‐embedding technique to study cotton roots in place. This was an effort to see if there was much particle orientation at the root surface‐soil interface. A limited number of sections failed to show much orientation but did show a packing effect. The use of colored plastic was investigated. It greatly facilitates thin section work as it makes identification of pore space much easier.
Soil Moisture Effects on Potassium Release Observed on Drying Soils with Organic Additives
Authors: Bates T. E. , Scott A. D.
Published: July 2010

A release of 223 ppm K occurred when Marshall subsoil samples were heated for 40 days in a drying oven at 110C. Most of this release can be attributed to the desiccation attained, not the heat, because similar heat treatments without drying increased the exchangeable K level by only 33 ppm.

The release of K associated with drying was entirely eliminated by adding organic compounds to the soil samples before they were dried. To attain this control of K release, however, it was necessary to dry the soil under conditions that ensured the presence of the organic compounds throughout the drying period. Otherwise, the effect of organic additives varied with the initial moisture level of the soil and the relative rates at which the water and organic additives were lost. Single additions of compounds with high boiling points were particularly effective in controlling K release, but even ethanol (boiling point 78C) prevented K release when it was maintained in the soil while the soil moisture was removed.

A practical method of controlling the release of K associated with drying involves the addition of 20 mmoles dextrose to 10 g soil. This treatment eliminates K release despite the presence of large amounts of water or the use of different drying rates.
Cation‐Exchange Capacity of Plant Lignins and Soil Humic Colloids as Affected by pH and Hydrolysis Error
Authors: Wildung R. E. , Chesters G. , Thompson S. O.
Published: July 2010

The effect of the pH of the buffered saturating solution on the cation‐exchange capacity (CEC) of several plant lignins and soil humic colloids isolated by NaOH and 1,4‐dioxane was determined for the pH range 2.5 to 8.0. The CEC of lignins ranged from 0 to 38 meq/100 g at pH 2.5 and 33 to 130 meq/100 g at pH 8.0, whereas the CEC of soil humic colloids ranged from 40 to 117 meq/100 g at pH 2.5 and 163 to 367 meq/100 g at pH 8.0. For the same plant or soil material, NaOH‐extracted samples were invariably higher in CEC than were dioxane‐extracted samples. The CEC values of the root lignins were lower than those of the shoot lignins irrespective of extraction method. The extent of hydrolysis error throughout the pH range was measured using two comparable CEC methods in which a water‐wash step was included in one case and omitted in the other. Maximum percentage hydrolysis error occurred at pH 2.5. Dioxane lignins of prairie grass and dioxane extracts of the 0‐ to 12‐inch layer of the virgin and cultivated Prairie soils were found to be more susceptible to hydrolysis errors than their NaOH‐extracted analogs.
The Influence of Aggregate Size on Soil Moisture Content‐Capillary Conductivity Relations
Authors: Amemiya M.
Published: July 2010

The capillary conductivity of beds of 0.5‐ to 1‐, 1‐ to 2‐, 2‐ to 3‐, 3‐ to 5‐, and 5‐ to 9‐mm aggregates separated from Nicollet, Kranzburg, Aastad, and Miami soils was determined over a suction range of from 0.02 to 12 bars by using the pressure plate outflow technique. When moisture content‐moisture suction relations were essentially unaffected by aggregate size, capillary conductivity was a function of volumetric moisture content. However, if moisture content‐moisture suction relations were affected by aggregate size, then at any given moisture content, conductivity values for a given aggregate size were inversely related to the suction corresponding to said moisture content. For beds consisting of mixtures of aggregate sizes, changes in moisture content‐moisture suction brought about by mixing, affected capillary conductivity in much the same way as in the case of beds of single‐sized aggregates. Data from sand and uniformly porous ceramic “aggregates” indicate that capillary conductivity is a function of size only if size affects moisture content‐moisture suction relations. Other factors influencing moisture retention may be expected to influence capillary conductivity accordingly.
Desorption of Glycerol from Clays as a Function of Glycerol Vapor Pressure
Authors: Hajek B. F. , Dixon J. B.
Published: July 2010

Glycerol desorption isotherms were developed for montmorillonite, vermiculite, kaolinite, and a mixture of montmorillonite and vermiculite at 95C and 80C. Application of the Langmuir equation to desorption data for montmorillonite indicated that 465 mg of glycerol was necessary for a complete monomolecular layer on all surfaces of 1 g of 2µ to 0.2µ clay. Although desorption data for vermiculite fitted the Langmuir equation, the adsorbed glycerol apparently was held at lower average density than for montmorillonite. Two intersecting straight lines fitted the desorption data for a montmorillonite and vermiculite mixture plotted according to the Langmuir equation, indicating that the two minerals could be distinguished quantitatively in the mixture. Multimolecular layers of glycerol appeared to be adsorbed on kaolinite at temperatures and pressures needed for duointerlayer (true monolayer) sorption by montmorillonite. Enthalpies of desorption from a Langmuir constant and from the Clausius‐Clapeyron equation compared favorably. Enthalpies ranged from 40 to 55 kcal/mole of glycerol desorbed from kaolinite and expansible minerals, respectively.
The Effects of Urea, Biuret, and Ammonia on Germination and Early Growth of Corn (Zea mays L.)
Authors: Hunter Albert S. , Rosenau William A.
Published: July 2010

Corn seeds were germinated near bands of fertilizer containing urea, biuret, cyanuric acid, ammonium, and certain other materials in sand‐solution cultures varying in urea and biuret, in closed systems containing gaseous NH3, and in soils with varying amounts of exchangeable NH4. Seeds were also soaked, before germination, in solutions of urea, biuret, (NH4)2SO4, or NH4OH. Germination was greatly inhibited by gaseous NH3 in closed systems, by more than 32% NH4‐saturation of the soil, and by soaking seeds in NH4OH; seeds that did germinate produced normal plants. In the field, germination was not affected but seedlings were injured by 1.5 lb or more of biuret‐N per acre (38‐inch rows); up to 1.5 lb cyanuric acid per acre had no harmful effects. Seed injury by NH3 released from urea is dependent upon hydrolytic activity, soil aeration, rate of nitrification, exchange capacity, and volume of soil between fertilizer and seed. Germination is affected by NH3; biuret principally affects seedling development after germination.
Inorganic Nitrogen Transformations Through the Oxidation and Reduction of Iron
Authors: Chao Tyng‐Tsair , Kroontje Wybe
Published: July 2010

In acid solution nitrate can be reduced by ferrous iron to N2 through such intermediates as nitrogen tetraoxide, nitrous acid, hyponitrous acid and nitrous oxide or through nitrogen tetraoxide, nitrous acid, nitric oxide, and nitrous oxide. These sequences show similarities to those occurring in the denitrification process. In a basic solution the reduction of nitrite to N2 may go through nitric oxide, N2O22‐, and nitrous oxide, or it may be reduced to ammonia through hydroxylamine, and hydrazine. Hydrazine and hydroxylamine are very unstable in the presence of iron in solution. In acid solution both hydrazine and hydroxylamine are oxidized by ferric iron to N2 and N2O. The amount of N2O formed is proportional to the ferric iron concentration.
The Dependence of Soil Water Uptake and Release Upon the Applied Pressure Increment
Authors: Davidson J. M. , Nielsen D. R. , Biggar J. W.
Published: July 2010

Two independent methods and three porous materials were used to ascertain whether or not the soil water content‐capillary pressure relation (soil water characteristic) depends on the rate at which soil water redistributes with applied capillary pressure increment. In one method small, uniform samples were subjected to known capillary pressures by means of a porous plate. The other method involved rotating 100‐cm long samples end‐to‐end at different rates and measuring the water content and capillary pressure distributions at equilibrium when the samples were vertical. The data from two soils, a silt loam and a sand, and a sandstone support the conclusion that the equilibrium water content depends on the size of the applied capillary pressure increment.
Influence of Added Aluminum on Carbon Dioxide Production in Tropical Soils
Authors: Mutatkar V. K. , Pritchett W. L.
Published: July 2010

Aluminum added to a yellow‐brown Latosol, as Al2(SO4)3, at rates of 6.6, 16.5, and 33.0 meg /100 g of soil decreased soil pH from 5.9 to 4.6, 4.0 and 3.8, respectively. Carbon dioxide production during 35 days of incubation decreased with increases in H‐ion concentration. In an attempt to separate the effects of H‐ion displacement from that of Al‐ion hydrolysis on microbial activity, Al‐treated soils were left unadjusted, or adjusted to pH 4.0, 5.5 or 6.5 before incubation.

Carbon dioxide production decreased with increases in added Al when the soil pH was maintained below about 4.0. Aluminum precipitated rather rapidly in soils with a higher pH and the Al had little influence on CO2 production. Less than 1 ppm of Al was extracted by 1n KCl when the final pH of the soil was above approximately 4.0 (as determined in neutral salt). Below this range, exchangeable Al increased with increases in amounts of Al initially added to the soil.

In a second experiment, a highly significant negative linear relationship was found between CO2 production and increasing percentages of Al in mixtures of Al‐ and Ca‐saturated Everglades muck. Furthermore, when Ca‐saturated muck was adjusted to pH 4.0 with HCl, and incubated, the production of CO2 was significantly greater than in Al‐saturated muck adjusted to pH 4.0. Since exchangeable Al did not increase when the Ca‐saturated muck was adjusted to a lower pH, but did increase when the pH of the Al‐saturated muck was lowered, it appeared that Al had an influence on CO2 production in these acid soils.
Survival and Reproduction of Two Species of Earthworm and a Rotifer Following Herbicide Treatments
Authors: Caseley John C. , Eno Charles F.
Published: July 2010

The survival and reproduction of Lumbricus terrestris Linné (Red Wiggler) and Eudrilus eugeniae Grinsburg, 1866 (African Giant) earthworms were followed in Everglades muck and Arredondo loamy fine sand treated with 11 herbicides at five rates.

Generally, E. eugeniae were more susceptible to the herbicides than L. terrestris and both suffered greater damage in Arredondo fine sand than in Everglades muck. Eggs and young were found in all treatments in the muck while none were observed in the fine sand. Several of the compounds had no effect, even at 64 ppm. Apart from dalapon, which had a significant effect on E. eugeniae at 8 ppm, the other compounds were ineffective below 16 ppm in Arredondo fine sand, and 32 ppm in Everglades muck. These levels are much in excess of the recommended rates for field applications.

Rotifers appear under moist conditions in most soils, and their diet includes soil algae. In solution culture, no direct toxic effects could be attributed to any one of the seven herbicides tested, but significant reductions in numbers of rotifers resulted from treatments which adversely affected the growth of unicellular algae. This demonstrated the indirect effect which some herbicides may have on an organism by way of a given food chain.
Effect of Soil Moisture on Ammonification and Nitrification in Two Northern Plains Soils
Authors: Reichman G. A. , Grunes D. L. , Viets F. G.
Published: July 2010

Samples of a Chestnut and Chernozem soil, with and without additions of (NH4)SO4 and K2HPO4, were incubated at constant water contents ranging from suctions of 0.2 to about 100 bars, and the exchangeable NH4‐ and soluble NO2‐N measured periodically. NO2‐N in excess of 1/3 ppm was never detected. Addition of P had no effect on N transformations. Ammonification and nitrification of soil N were almost directly proportional to soil water content at suctions between 0.2 and 15 bars. Measurable ammonification and nitrification occurred at a suction of 15 bars.
Evidence Indicating the Presence of Loosely‐Bound Phenolic Groupings in Soil Organic Matter Extracts
Authors: Keefer R. F. , Himes F. L. , Mortensen J. L.
Published: July 2010

Purified low molecular weight material from a sodium hydroxide extract of a peat soil was separated by paper chromatography into at least 8 components which coupled with diazotized spray reagents suggesting the presence of phenols, aromatic or aliphatic amines, β‐diketo groups, imidazoles, or other highly reactive compounds. The color reactions with the diazonium sprays indicate the presence of derivatives of catechol and resorcinol. Aromaticity is further suggested by infrared spectra of fractions of the fulvic acid. Two components appear to be of the flavonoid type.
Sulfur Requirements for Decomposition of Cellulose and Glucose in Soil
Authors: Stewart B. A. , Porter L. K. , Viets F. G.
Published: July 2010

The rates of glucose and cellulose decomposition in soils treated with adequate N and P were dependent on the S level More S was required for a maximum decomposition rate of cellulose than for glucose. A minimum of 1 part S to 300 parts C was required for maximum cellulose decomposition, whereas 1 part S to 600–900 parts C was sufficient for maximum decomposition of glucose. One factor for the higher S requirement for cellulose decomposition may be that more S is required in the production of extracellular enzymes essential for cellulose decomposition.
Wind Erosion as Influenced by Row Spacing, Row Direction, and Grain Sorghum Population
Authors: Skidmore E. L. , Nossaman N. L. , Woodruff N. P.
Published: July 2010

Replicated plots of grain sorghum (Sorghum vulgare) with 21‐ and 42‐inch row spacings and three plant spacings within each row spacing were established on Dalhart sandy loam in 1963 and yield data were obtained. In March 1964, four wind tunnel tests were conducted one ach plot, two with wind blowing parallel to row direction and two perpendicular. Sorghum stubble residue was sampled and analyzed The results were interpreted in terms of natural wind conditions for sample locations in the Great Plains by applying previously developed procedures to determine prevailing wind erosion direction and preponderance of wind erosion forces in the prevailing wind erosion direction.

Soil loss was reduced by narrow row spacing, high plant population, and rows perpendicular to wind direction. Nearly three times as much erosion occurred with wind blowing parallel as perpendicular to row direction.

The combined advantage of narrow row spacing (21‐inch) and rows perpendicular to prevailing wind erosion direction reduced soil loss from 29 to 55%. Greater reductions result when a larger proportion of wind erosion forces occur in the prevailing wind erosion direction.

Plant residue and grain yield increased significantly with higher plant population. Grain yield was not significantly affected by row spacing.

Based on the results of this study and for similar conditions, for decreased wind erosion and maintenance of grain yields one should (i) plant high plant populations within the recommended range, (ii) plant in narrow row spacings, and (iii) where field layout permits, plant perpendicular to prevailing wind erosion direction.
Surface Chemistry of Hematite: Anion Penetration Effect on Water Adsorption
Authors: Jurinak J. J.
Published: July 2010

The adsorption of water by αFe2O3 (hematite), using high vacuum techniques, was studied. The surface of hematite was treated with phosphate, sulfate, or molybdate and activated at various temperatures prior to adsorption studies. The anion treatment had no apparent effect on the physical adsorption of water. The hematite surface was found to adsorb one water molecule/23‐24A2 whereas an OH group on the hematite surface was found to occupy an effective area of 22–23A2. Water adsorption on OH sites is inferred. About 45 to 47% of the oxide surface was found to physically adsorb water. Chemisorbed or OH water was influenced by anion treatment and was related to both the density of the OH population and the mobility of the associated proton. Both water and anion reaction with the surface is discussed.
Distribution of Nitrogen Fixed in Desert Algal‐Crusts
Authors: Mayland H. F. , McIntosh T. H.
Published: July 2010

Fixation of isotopically labeled N2 by desert algal crust organisms was very rapid after initial wetting of crusts. After 8 days of incubation, a steady rate of fixation was reached which continued for 152 days.

The initial distribution of N was 4% extracellular NH4, 16% acid‐hydrolyzable NH4 (included extracellular NH4), 41% α amino acid, 4% hexosamine, 29% acid‐hydrolyzable but unidentified, and 11% non‐hydrolyzable. After 21 days of incubation the distribution of total N was 2, 18, 42, 2, 29 and 11%, respectively. The distribution of excess N15 after 21 days of incubation was trace, 12, 51, 2, 29 and 7% for the respective fractions. Continued incubation had little effect on the relative distribution of N in the several fractions.
Influence of Natural Drainage on the Distribution and Forms of Phosphorus in Some Iowa Prairie Soils
Authors: Runge E. C. A. , Riecken F. F.
Published: July 2010

Total, inorganic, organic, and available P were determined for 12 loess‐derived prairie soil profiles. The amount of total phosphorus (TP) is high near the surface, has minimum values from 1 to 3 ft, has maximum values from 3 to 6 ft, and has nearly uniform values below 6 to 7 ft. The higher amounts near the surface are due to organic phosphorus (OP). The amount of OP in the poorly drained soils is about one‐half that in the better drained members of the topo‐sequence.

Differences in organic carbon (OC)/OP ratios between the poorly and better drained soils are appreciable, with the poorly drained soils having the higher ratios.

Difference in extractable or available phosphorus (AP) within and between profiles may be interpreted when pH, extractable Fe and Al, rooting depth of plants, TP and OC/OP ratios are considered. Phosphorus differences between soils of southeast and southwest Iowa are appreciable. The role of P in soil genesis studies is discussed.
Crop Response From Tile and Surface Drainage
Authors: Schwab Glenn O. , Taylor George S. , Fouss James L. , Stibbe Ehud
Published: July 2010

The effects of various drainage systems and different levels of N treatments on corn (Zea mays) yields were evaluated for a fine‐textured lakebed soil during a period of 3 years. The drainage treatments consisted of undrained plots, surface drained, the drained, and a surface and tile drained combination. Excess wetness was provided each year by sprinkling all plots in June and July. The three drained treatments gave significantly higher yields than the undrained treatment, and N increased corn yields significantly at all drainage levels.

An economic evaluation of the drainage systems with a N application of 100 lb/acre showed that the benefit/cost ratio for surface drains was 10:1; tile drains 6:1; and the combination tile‐surface drainage system 4:1, when compared to the un drained treatment. The study indicated that the surface drainage system gave the greatest benefit per dollar invested in the drainage system.
Effects of Stones on Runoff, Erosion, and Soil Moisture
Authors: Epstein E. , Grant W. J. , Struchtemeyer R. A.
Published: July 2010

Studies on a caribou silt loam at Presque Isle, Maine were conducted to determine the effect of stones on runoff, erosion and soil moisture. The three treatments consisted of a control, stones over 3.81 cm in diameter removed, and stones over 3.81 cm removed, crushed and reincorporated into the soil. Removing the stones increased soil and water losses over a 4‐yr period. Infiltration and soil moisture was decreased as a result of stone removal. Crushing and returning the stones resulted in soil losses similar to that obtained under normal soil conditions. During 1961–1964, 20 storms produced 75% of the total soil loss and about 55% of the total runoff.
Zinc Availability for Corn as Related to Source and Concentration in Macronutrient Carriers
Authors: Giordano P. M. , Mortvedt J. J.
Published: July 2010

Zinc oxide, ZnSO4, and ZnS were tested as sources of Zn at rates of 1, 2, and 4 ppm Zn for two successive crops of corn (Zea mays) grown on Nolichucky sandy clay loam (pH 7.3). Each source was mixed throughout the soil as finely ground material, incorporated into granules of ammonium nitrate (AN) or ammonium polyphosphate (APP) by pressure granulation, and into granules of concentrated superphosphate (CSP) during the granulation stage of the manufacturing process. When mixed with the soil ZnO and ZnSO4 were more effective than when incorporated with a macronutrient carrier. Both ZnO and ZnSO4 were markedly superior to ZnS. Ammonium nitrate and APP were comparable carriers when ZnSO4 was the source, but APP was superior to AN when ZnO was used. A higher concentration of Zn in the CSP granules resulted in poorer response to this carrier. Zinc oxide was pressure granulated with CSP, AN, APP, or Nolichucky soil to contain 0.5, 2.0, or 8.0% Zn. Soil granules and CSP were applied at 1, 2, and 4 ppm Zn while AN and APP were applied at 2 ppm only. Forage yields and Zn uptake varied inversely with concentration of Zn in all carriers.
A Comparison of Clay Contents Determined by Hydrometer and Pipette Methods Using Reduced Major Axis Analysis
Authors: Liu T. K. , Odell R. T. , Etter W. C. , Thornburn T. H.
Published: July 2010

Test results on the amount of <0.002 mm clay determined by hydrometer and pipette methods have been obtained from 155 duplicate soil samples, of which 48 are from Illinois and the remaining 107 are from soil survey reports published by the Soil Conservation Service in cooperation with 10 other states. Correlation analysis of the data yielded a highly significant coefficient of 0.965. The best‐fit line between the clay contents determined by these two procedures was obtained by the reduced major axis method of statistical analysis. In this statistical method, neither one of the two variables is considered as the dependent variable and the reduced major axis is determined by mininizing the sum of the areas of triangles formed by lines drawn from each point to the best‐fit line and paralle with the X and Y axes. The relationship between the clay contents is expressed by the equation Y = 0.63 + 1.008 X, in which X and Y represent the pipette and hydrometer clay content, respectively. Clay contents determined by these two methods are quite similar, although there is a tendency for hydrometer analyses to be slightly higher. Relationships between data from Illinois and other states are very similar. The slightly poorer correlation between clay contents of A horizons as compared to other horizons may have been caused by organic matter which was not removed in hydrometer analysis.