bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phosphorus Solubility in Calcareous Soils: I. Dicalcium Phosphate Activities in Equilibrium Solutions
Authors: Cole C. V. , Olsen S. R. 
Published: July 2010

AbstractA theoretical background for the study of P solubility behavior in calcareous soils has been developed. The mean activity of dicalcium phosphate is used to express P solubility. Calculation of this function corrects for differences in the pH values, Ca concentrations, and ionic strengths which are encountered when a number of soil solutions are compared. The validity of this approach is based on the observation that the ion product aCa++ × aHPO4= in various solutions in equilibrium with a given soil remains constant over a range of values of pH, Ca concentration, and ionic strength.
Modern Concepts of the Genesis of Podzols
Authors: Stobbe P. C. , Wright J. R. 
Published: July 2010

AbstractThe major processes suggested in the literature for the formation of Podzols have been reviewed. Theories on the formation of negatively charged humus‐protected sols and of metal‐organic coordination complexes, including chelates, and on the immobilization of the sesquioxides and organic matter in the B by microbial activity, sorption and oxidation have been presented. It is concluded that, while the theories of complex formation and possibly chelation appear reasonable, more factual information is required on the constitution of the reacting organic substances and on the precipitation mechanism involved.
Adsorption of Hydrolyzed Polyacrylonitrile on Kaolinite: II. Effect of Solution Electrolytes
Authors: Mortensen J. L. 
Published: July 2010

AbstractAdsorption experiments were conducted by mixing NaCl‐kaolinite and C14‐labelled hydrolyzed polyacrylonitrile (HPAN) in water solutions of various electrolytes. An increase in the concentration of electrolyte caused an increase in extent of HPAN adsorption, the effect apparently being due to reduction of electrostatic repulsion between HPAN and kaolinite and reduction in size of the HPAN coil. Divalent cations, especially the transition metals capable of being complexed, were more effective than univalent cations. Maximum adsorption took place in the presence of H+ ions.Anions capable of complexing lattice aluminum and/or decomposing the clay crystal reduced adsorption of HPAN. There was some evidence of competition for adsorption sites.
Organic Matter Decomposition as Influenced by Oxygen Level and Method of Application to Soil
Authors: Parr J. F. , Reuszer H. W. 
Published: July 2010

AbstractLaboratory experiments were conducted to determine the rate of decomposition of straw added to soil as a localized placement or mixed thoroughly with the soil when aerated with N2‐O2 gas mixtures containing 0, 2.5, 5.0 and 21% oxygen. Rates of decomposition and total decomposition were followed by determination of CO2 formed.Early decomposition rates were somewhat lower with localized placement of the straw, but after 6 weeks of incubation there was little difference between the two methods of placement in total amount of straw decomposition.Total decomposition after 6 weeks with 5.0, 2.5, and 0% oxygen in the aerating gas was equal to about 86, 70, and 13%, respectively, of that taking place when the aerating gas contained 21% oxygen. After 30 days of aeration at a 0% oxygen level, changing the aerating gas to a 21% oxygen level brought about a very rapid rise in the rate of decomposition.
Laboratory and Greenhouse Studies with Monocalcium, Monoammonium, and Diammonium Phosphates
Authors: Bouldin D. R. , Sample E. C. 
Published: July 2010

AbstractPellets of monocalcium phosphate monohydrate (MCP), monoammonium phosphate (MAP), and diammonium phosphate (DP) containing 15 mg. of P were placed on the surface of moist Hartsells fine sandy loam (pH 5.2) and Webster silty clay loam (pH 8.3). After 3 and 5 weeks the distribution and solubility of the soil‐fertilizer P reaction products were measured with soil samples taken at various radial distances from the center of the pellets. Plant response to pellets of fertilizer was measured in greenhouse experiments.With both soils, distribution of total fertilizer P did not change appreciably in the interval between sampling periods. Fertilizer P moved about 2.5 and 1.5 cm. from the center of the pellets with the Hartsells and Webster soils, respectively. Differences among sources in the same soil were relatively small.With the Hartsells soil, 6.5 and 11% of the fertilizer P was soluble in 1:15 soil‐water extracts with the MCP and DP sources, respectively; with the Webster soil the corresponding figures were 5.2 and 1.0%. The measurements of water‐soluble P in the laboratory explained 85% of the variation in plant uptake of P with the different fertilizers in greenhouse experiments. In laboratory and greenhouse experiments DP was superior to MCP in the Hartsells soil, while MCP was much superior to DP in the Webster soil. MAP was intermediate in behavior between the 2 other sources with the Hartsells soil, but was roughly equivalent to MCP with the Webster soil.
The Effect of Soil Solution Aluminum and Calcium on Root Growth
Authors: Ragland John L. , Coleman N. T. 
Published: July 2010

AbstractThe effect of lime level on the growth of grain sorghum roots into subsoils of the Norfolk catena was studied in a greenhouse experiment. The effects of lime and KCl on root growth of sweet corn and on soil solution concentrations of Al were investigated in a second greenhouse experiment. The latter was pursued further by growing grain sorghum plants in suspensions of White Store clay to which had been added various quantities of Ca(OH)2 and CaCl2.The growth of roots into unlimed subsoils from the Norfolk catena was related inversely to the amounts of exchangeable Al. The percentage Al‐saturation of the catena members increased with decreasing natural drainage. Root growth into the subsoils increased substantially when lime sufficient to cause hydrolysis of the exchangeable Al was added.The addition of KCl to unlimed Creedmoor, Portsmouth, and Appling soils increased the concentration of Al in soil solution to the point that growth of sweet corn roots was drastically reduced. When lime was added, corn roots grew well even at the highest level of KCl.The development of roots by grain sorghum plants grown in suspensions of acid White Store clay (30 me. exchangeable Al per 100 g.) was restricted severely unless 80% of the acidity was neutralized. This was particularly true for the highest rate of CaCl2.
Approximation of the Field Maximum Soil Moisture Content
Authors: Carlson Charles A. 
Published: July 2010

AbstractField maximum moisture content is defined as the recurring maximum moisture content of a soil layer in its natural position. An approximation of the field maximum is needed when daily moisture records are not available for selecting the recurring peak values. This paper presents the approximation of the field maximum moisture content from equations relating various soil and site properties.Of the several factors investigated, the 0.06‐atm. soil moisture tension value was the only single factor that correlated significantly with the field maximum; it accounted for about 68% of the variation in the field maximum values. With a simultaneous analysis, the sand content and the wetness index of the soil layer also were found to be primary factors in estimating the field maximum moisture content. Wetness index is an arbitrary classification that rates the potential maximum wetting of the 0‐ to 12‐inch layer of soil and is dependent on the depth to a water table and the depth of wetting. Organic content and clay content were found to be secondary factors in the 0‐ to 6‐ and 6‐ to 12‐inch layers, respectively. Equations using all factors accounted for about 80% of the variation in the field maximum values. The usefulness of the equations was evaluated by application to 533 sites located throughout the United States.
Freezing‐Point Depressions in Stabilized Soil Aggregates, Synthetic Soil, and Quartz Sand
Authors: Cannell Glen H. , Gardner Walter H. 
Published: July 2010

AbstractThe freezing‐point method, using a small probe‐type thermistor as the sensing element, was used to study certain factors believed to lower the freezing‐point depression of soil moisture. The factors investigated were aggregate size, particle size, and undercooling temperature. The materials used were homogeneous and consisted of Palouse silt loam obtained from the A1 horizon, synthetic soil, and quartz sand.The Palouse silt loam was treated with soil conditioner, formed into aggregates, and separated into groups of various sizes. The freezing‐point depression measured on the various groups of aggregates increased with decreasing size of aggregates. This same trend was obtained for different‐sized sand separates. With successive freezing and thawing, the freezing‐point depression decreased for Palouse silt loam aggregates but was relatively unchanged for sand separates.The synthetic soil was made from ground quartz sand and illite clay. Part of the synthetic soil was treated with various rates of soil conditioner and formed into aggregates. The freezing‐point depression, made on aggregates of 1 to 2 mm. diameter, increased with increasing rate of soil conditioner.Different undercooling temperatures had little effect in changing the freezing‐point depression for Palouse silt loam or sands. However, the freezing‐point depression was increased with increasing undercooling temperatures for nonaggregated synthetic acid‐soil.
Aluminum Fixation in a Synthetic Cation Exchanger
Authors: Hsu Pa Ho , Rich C. I. 
Published: July 2010

AbstractPrevious studies of soils have indicated fixation of Al as a poistively charged ion or polymer by some clay minerals. To avoid reactions with structural Al in clays, a synthetic cation‐exchange resin, Dowex‐50, was employed in a preliminary study of Al fixation. This resin was Al‐saturated and then serially titrated with NaOH. In a similar experiment, AlCl3 was added in an amount equivalent to the Al in the resin, prior to titration. In a third experiment the same amount of Al‐saturated resin was added to different volumes of solutions containing NaOH and AlCl3 in molar ratios of 0.296, 1.185, and 2.37, respectively. All of these experiments indicate that the only exchangeable Al ion was Al3+ and that in the acid range nonexchangeable Al was fixed so that on the average one positive charge of the resin was countered by one Al ion. A gibbsite‐like ring structure having 6 Al ions, 12 OH ions and 12 water molecules is proposed as the principal fixed hydroxy‐Al polymer. The polymer may be formed in place from smaller chain‐like polymers and fixed because of its large size and high charge.
The Effectiveness of Various Manganese Materials in Supplying Manganese to Crops
Authors: Shepherd L. , Lawton K. , Davis J. F. 
Published: July 2010

AbstractField tests on Houghton muck and greenhouse studies on alkaline organic and mineral soils were conducted to determine the comparative effectiveness of several manganese carriers as measured by yield response and manganese content of crops. Spray, broadcast, and banding methods of application were studied in field tests and mixing vs. banding of carriers was studied in the greenhouse. Carriers used in the field studies were manganese sulfate, NuM, Mangasoil, NuManese, and FN 239 B frit. In addition to the above five carriers, FN 502 frit and disodium manganous EDTA were used in the greenhouse. The indicator crops were onions in the field, and corn, beans and wheat in the greenhouse.In field studies, the methods of application in order of effectiveness in increasing the yield of onions were banding, broadcasting, and spraying. In 1957, where the manganese carriers were mixed with the basic fertilizer and banded 2 inches below the seed, a significant yield response to manganese was obtained regardless of the carrier used. No difference was observed between carriers or rates applied (10 and 20 pounds of manganese per acre).Greenhouse results indicated a high residual value on Houghton muck for Mn EDTA followed by FN 239 B, NuManese and manganese sulfate. The difference between the latter two was nonsignificant. On the mineral soil, mixing the carriers throughout the soil gave a significant yield response only with the wheat crop when compared to band applications.
Weathering and Aluminum Interlayers in a Soil Catena: Hollis — Charlton — Sutton — Leicester
Authors: Sawhney B. L. 
Published: July 2010

AbstractLarge amounts of a mineral with a stable 14Å. spacing are present in clay fractions of the Hollis‐Charlton‐Sutton‐Leicester catena. When subjected to the usual procedures for the characterization of clay minerals, this mineral exhibited a behavior between that of vermiculite and chlorite. It was identified as vermiculite after interlayer aluminum was removed. Mild acid conditions and abundant illite and vermiculite in the parent micaceous schist are significant factors in forming these aluminum interlayers. The stability of aluminum interlayers both to sodium citrate and heat treatments increased with proximity to the surface. In Charlton fine sandy loam, 6 to 9 hours extraction with N sodium citrate were required to remove interlayers in the A1 horizon, whereas only 3 and 6 hours sufficed for the C and B22, respectively. The aluminum interlayers in well‐developed and well‐drained Charlton and Sutton soils are more stable to heat treatments than the material in poorly drained Leicester and shallow Hollis soils.The cation‐exchange capacity increased as much as 30 to 40% after the removal of aluminum interlayers; the increase was greater in more stable samples. Aluminum interlayers produced experimentally in vermiculite and montmorillonite resulted in stable 14Å. spacing and lowered the cation‐exchange capacity of the original minerals considerably.
Effects of Electrolyte Imbibition Upon Cation‐Exchange Behavior of Soils
Authors: Thomas Grant W. 
Published: July 2010

AbstractIon‐exchange chromatography was employed to study the effects of electrolyte imbibition by soils on their cation‐exchange behavior. This was accomplished by study of the shape of effluent breakthrough curves from columns of Ca‐saturated soils to which either Al+3 or K+ solutions were added. B‐horizon samples of Cecil, Lloyd and Davidson, and the Ap horizon of a Yolo soil were employed in the study.Comparison of experimental effluent curves with those predicted by the modified Walter equation showed a large discrepancy when anion interaction with soils was encountered. Anion distribution coefficients (Kd's) varied in the order Cl‐ = NO3‐ < SO4‐2 < H2PO4‐ on a Ca‐Lloyd soil. Only H2PO4‐ had a Kd above zero on the Yolo soil. Column “symmetry values” for Ca+2 → K+ exchange were reduced as electrolyte imbibition by soils increased. Practical implications of these results are discussed.
Yield Response in Experiments With Phosphorus Fertilizers in Relation to: I. Meaningful Differences Among Sources on Acid Soils of the Southeastern States
Authors: Terman G. L. 
Published: July 2010

AbstractYield results from 174 phosphorus rate and source experiments conducted in the Southeast, each including a response curve with CSP (concentrated superphosphate), were examined in relation to the nature of the response and experimental error.In only a few of the tests with various crops showing yield response to P was it possible at the 5% probability level to measure differences among citrate‐ and watersoluble sources which were from one‐half to twice as effective as CSP. Under the conditions where grown, cotton was the poorest crop for this purpose, corn and small grain grown for grain were intermediate, and annual forage was best. The possibility of measuring differences among sources decreased with increase in soil P level and with increase in the rate of application of P at which the comparison was made.Estimated limiting yields of cotton on low‐yielding sites without applied P were lower than most of the check yields at sites of higher productivity. A similar, but less pronounced situation prevailed with corn, but not with small grain. Deficiency of water is thought to be the chief factor limiting yields of summer‐grown cotton and corn at all yield levels, but not of winter‐grown small grain.
The Effect of Associated Salts on Transformations of Monocalcium Phosphate Monohydrate at the Site of Application
Authors: Bouldin D. R. , Lehr J. R. , Sample E. C. 
Published: July 2010

AbstractThe effect of associated nonphosphatic salts on the transformation of reagent‐grade monocalcium phosphate monohydrate (MCP) during dissolution at the granule site was examined in Hartsells fine sandy loam (pH 5.2) and in calcareous Webster silty clay loam (pH 8.3).The fraction of the added phosphorous that remained as a residue at the granule site varied from 92% when MCP was mixed with CaCO3, to only 2% when ammonium sulfate was mixed with MCP. Uptake of phosphorus by plants grown on the soil‐fertilizer systems after removal of the residues indicated that plant response was influenced by both the quantity of phosphorus actually transported into the soil, and the composition of the solution in which the phosphorus was transported.The data further support the concept that during dissolution of the granule, the soil has relatively little influence on the chemistry of the reactions taking place in the granule. Consequently, laboratory phase‐rule studies may be quite useful in estimating: (a) the fraction of phosphorus that will remain as a residue at the placement site, and (b) the composition of the solution leaving the granule. The latter is of utmost importance in studies of soil‐fertilizer phosphorus reactions.
The Availability of Chelated Mn to Millet and Its Equilibria With Other Forms of Mn in the Soil
Authors: Walker John M. , Barber Stanley A. 
Published: July 2010

AbstractThe use of insoluble soil‐chelated Mn, in addition to exchangeable Mn, did not increase the predictability of available Mn. In this study, 12 Indiana soils varying in organic matter, pH, texture, and parent material were collected and treated to give two levels of Mn and acidity. Available Mn was determined by cropping the soils with German Millet.Exchangeable Mn was the most important factor in determining available Mn. Since chelated and exchangeable Mn were highly correlated, the true effect of chelated Mn may not have been apparent. Inclusion of the interaction chelated Mn times percent organic matter highly significantly increased the ability to predict available Mn. Soil pH was also significant in predicting available Mn.The increase in chelated and exchangeable Mn on airdrying of the soils was related to total soil Mn.
The Efficiency of Various Particle‐Size Fractions of Limestone
Authors: Motto H. L. , Melsted S. W. 
Published: July 2010

AbstractThe relative efficiency of various fractions of a calcitic limestone was studied under greenhouse conditions. Pure calcium carbonate, a commercial sample of agricultural limestone, and 6 particle‐size fractions separated from this commercial sample were applied at different rates to 3 acid soils. The soils were sampled at various times and the pH determined. The changes in pH with time followed an expression of the form, pHf = pHo + b Log (1 + t). The factor b varied with rate of application, particle size, and soil.The limestone particles in the 10‐ to 28‐mesh size fraction were, in general, 14% as effective as those in the < 100‐mesh fraction, and particles > 10 mesh were essentially of no value. The efficiency of the commercial sample of agricultural limestone was approximately equal to that exhibited by the 40‐ to 60‐mesh fraction of the sample. The results indicate that, for practical purposes, a large portion of commercial limestone should be ground fine enough to pass a 40‐mesh sieve.
Fertilizer Evaluation: IV. Use of P32‐Labeled Fertilizers
Authors: Bouldin D. R. , Black C. A. 
Published: July 2010

AbstractTwo different measures of the yield of fertilizer phosphorus were defined as follows: (1) The net increase in yield of phosphorus from fertilization is equal to the yield of phosphorus in the phosphate‐fertilized crop minus the yield of phosphorus in the control. (2) The yield of true fertilizer phosphorus is the yield of the atoms of phosphorus actually applied in the fertilizer and is equal to the product of (a) the yield of phosphorus in the phosphate‐fertilized crop and (b) the ratio of the specific activity of phosphorus in the crop to that in the fertilizer. Measurements of these two kinds of yields of fertilizer phosphorus were made on a crop grown in greenhouse cultures on 6 soils with 4 particle sizes of P32‐tagged monobasic sodium phosphate applied at 4 rates. The net increases in yield of phosphorus from fertilization exceeded the yields of true fertilizer phosphorus, and the difference between these two values increased with the quantity of labile phosphorus in the soil. These observations can be explained on the basis of (a) enhanced growth of roots and absorption of soil phosphorus in the nonfertilizer‐affected soil in the presence of fertilizer, (b) enhanced absorption of soil phosphorus in the fertilizer‐affected soil, or (c) a combination of (a) and (b), but no evidence permitting a choice of hypotheses was obtained.
Influence of Molybdenum on Growth and Composition of Alfalfa and Distribution of Molybdenum in a Cecil‐Lloyd Soil
Authors: Giddens Joel , Perkins H. F. 
Published: July 2010

AbstractSodium molybdate was applied annually at a rate of 8 ounces per acre to alfalfa receiving 500 and 4000 pounds limestone. Beginning in the fall of the second year of growth, the low lime treatment plus molybdenum yield was about the same as the high lime treatment. After 3 years, alfalfa on the high lime treatment responded to molybdenum. Liming increased the molybdenum content of alfalfa in 1956 but did not consistently do so in 1959. The molybdenum content of alfalfa was not excessive after six applications. Molybdenum did not move downward in the Cecil‐Lloyd soil profile.
Stubble Mulching With Various Types of Machinery
Authors: Fenster C. R. 
Published: July 2010

AbstractStubble‐mulch farming has been recognized as the simplest and surest way of preventing wind erosion in the Great Plains. Maintaining residues for adequate soil protection while controlling the weeds and preparing the seedbed has been a major problem in a stubble‐mulch program. Reduction of surface residues should be held to a minimum unless they are excessive. Tillage and planting tools have various characteristics in their ability to conserve or reduce residues, to work in heavy residues, to control weeds, to penetrate the soil and keep the soil in good tilth for proper germination and plant growth. Satisfactory stubble‐mulch tillage equipment is now available from major implement companies. The correct machines can be selected by making an inventory of the residues at the beginning of the tillage season, and by determining the amount of residues necessary to protect a given piece of land. With proper equipment, knowledge and ability, a year‐round system of managing plant residues can be used in which all tilling, planting, cultivating, and harvesting operations are performed to keep a constant protective cover on the land.
Growth and Water Absorption by Corn as Influenced by Soil Moisture Tension, Moisture Content, and Relative Humidity
Authors: Peters D. B. 
Published: July 2010

AbstractWhen plants were subjectd to a high evaporative demand, i.e., low relative humidity, growth was found to be profoundly influenced by both soil moisture tension and moisture content. However, at low evaporative demand, other factors being held constant, growth was influenced by moisture tension and moisture content in only a minor way. Thus, it is shown that evaluation of growth from the standpoint of water use must consider the total free energy path causing water movement. Water use could not be evaluated precisely with the experimental technique used because of the large growth differences and the inability to measure energy absorption by plants.