bluuebunny/crossref_metadata_2025_split huggingface dataset:
Approximate Solution of a Non‐Steady‐State Drainage Problem
Authors: Gardner W. R. 
Published: July 2010

AbstractFlow in the unsaturated zone during one‐dimensional drainage is taken into account approximately by assuming the water content to be a linear function of the hydraulic head. The problem is then treated as one in unsaturated flow. After a brief initial period, the rate of outflow should decrease exponentially with time, with the outflow rate proportional to the soil‐water diffusivity. Agreement with experimentally determined outflow rates is reasonable; however, the exact water content distribution cannot be calculated. The treatment is extended to two dimensions by the equivalent of the Dupuit‐Forchheimer assumption. The total amount of water in the profile at any horizontal distance from a drain is calculated rather than the position of the water table. The theoretical outflow is in good agreement with results of sand tank and field measurements.
Effect of Anions in the System on the Amount of Cations Adsorbed by Soil Materials
Authors: Sommerfeldt Theron G. 
Published: July 2010

AbstractWells fine sandy loam and Utah bentonite (noncalcareous) were equilibrated in solutions of NaOH, NaCl, Na2CO3 and Na2SO4 to determine the effect of the different anions on the amount of cations retained by these materials.Total exchangeable cations, exchangeable sodium and exchangeable calcium plus magnesium, as extracted by NH4OAc method, were greatly affected by the anions in the systems.Various possibilities for these results have been discussed. It was concluded that the adsorption capacity of the materials had not remained constant, but varied with the anion environment, and that this was the most important factor responsible for these results.
Some Aspects of Zinc and Copper Phosphate Formation in Aqueous Systems
Authors: Jurinak J. J. , Inouye T. S. 
Published: July 2010

AbstractZinc and copper systems were titrated with NaOH in the presence of varying amounts of KH2PO4. The data indicated zinc formed the orthophosphate, Zn3(PO4)2 · 4H2O while copper precipitated as the basic phosphate, Cu5(H2PO4)2(OH)8. The pKsp calculated from the dissociation of these phosphates at their respective isoelectric pH values were 47.9 and 92.5 for zinc and copper phosphate, respectively. Basic copper phosphate was less soluble than zinc orthophosphate at all pH levels studied.
Chemical Relationships Affecting the Water‐Holding Capacities of Clays
Authors: Thomas Grant W. , Moody John E. 
Published: July 2010

AbstractThe relation between water‐holding capacity and clay properties was studied on Wyoming bentonite and four Virginia soil clays ranging in mineralogical type from montmorillonite to kaolinite. The amount of water held at 1/3 atm. pressure was closely related to clay type and cation saturation; the Na‐montmorillonites containing much more water than any other clays. At 15‐atm. pressure there was little difference in water held between any of the clays regardless of cation saturation or clay type. The only exception was Na‐bentonite which held 71% H2O compared to a mean of 48.6 ± 3.2% among all the other clays. Analyses of displaced solutions from the clay suspensions showed that only in Na‐montmorillonites was the predicted double‐layer pattern of reduced anion concentration at lower water contents followed. This and the fact that other clays apparently did not imbibe much water between layers support the idea that the double‐layer theory is applicable only to freely‐expandable clay minerals.
Inefficiency of Fertilizer Use Resulting from Nonuniform Spatial Distribution: III. Fractional Segregation in Fertilizer Materials
Authors: Jensen Don , Pesek John 
Published: July 2010

AbstractPartial stratification of dry‐blended fertilizer materials may occur as a result of different physical properties of the component nutrient carriers. Nonuniform nutrient distributions arise, in spite of uniform application of the mixture, because nutrient ratios and analyses vary among strata. Nutrient segregation is illustrated by a linear relation between nutrient rate and distance traveled by a fertilizer applicator.Fertilizer distributions may also be influenced by spreading characteristics of the fertilizer applicator. Yields associated with nonuniform application of a segregated mixture were evaluated by substituting an appropriate distribution function into a specific yield equation and integrating over the treated area.Algebraic results of the derivations are illustrated numerically for corn produced on a calcareous Ida silt loam in Iowa. Yield losses induced by nutrient segregation alone may reach 5 bushels per acre for selected degrees of severity of stratification. For the particular distribution patterns considered, additional yield losses of up to 6.1 bushels per acre may result from nonuniform application of a segregated fertilizer mixture.
Nitrification of Ammonium Sulfate in a Calcareous Soil as Influenced by Combinations of Moisture, Temperature, and Levels of Added Nitrogen
Authors: Justice John Keith , Smith R. L. 
Published: July 2010

Abstract(NH4)2SO4 at levels of 0, 150, and 450 ppm. N was incubated in a calcareous soil at 2°, 10°, and 22° C. at 10, 1, and 0.3 bars moisture tension using periodic aeration. A second incubation study included 4 other moisture levels (7, 15, 115, and 415 bars moisture tension) and continuous aeration. Good control of the moisture was attained with the continuous aeration by humidifying the incoming air over saturated salt solutions known to give the required relative humidity. The soil used, Millville loam from the Agronomy farm, is a highly calcareous (47% CaCO3 equivalent) fertile soil with a saturated paste pH of 7.8, and moisture contents at field capacity (0.3 bar tension), permanent wilting percentage (15 bars tension), and air dry of 18.0, 6.9, and 1.6%, respectively.The only evidence of nitrification at 2°C. was the production of NO2‐N which was not converted to NO3‐N in 10 weeks. At 10°C. there was nitrification at ⅓, 1, and 10 bars tension where the lowest moisture (10 bars tension) apparently only delayed the initiation of nitrification and did increase the period of NO2‐N accumulation. At 25°C. nitrification was completely inhibited at 415 and 115 bars tension. At 15 bars tension 50% of the 150 ppm. N was oxidized to NO3‐N in 28 days, while at 10, 7, and 1 bars tension the nitrification was complete in about 28, 20, and 12 days. In this soil, 35°C. was less favorable for nitrification than 25°C. NO2‐N accumulated at this temperature and persisted throughout the 8 weeks. Temperature (both high and low) and lowered moisture had a greater inhibiting effect on NO2‐N oxidizers than on NH4‐N oxidizers.There was a decrease in the total inorganic N recovered when unfavorable nitrification conditions were encountered. This loss of inorganic N was apparently from the NH4‐N pool.
Effect of Soil pH and Texture on the Availability of Water‐Soluble Boron in the Soil
Authors: Wear John I. , Patterson R. M. 
Published: July 2010

AbstractA greenhouse study was conducted with alfalfa to determine the relationship between water‐soluble B in the soil and plant uptake as affected by soil texture and pH. Soils used were Norfolk sandy loam, Hartsells fine sandy loam, and Decatur silty clay representing coarse‐, medium‐, and fine‐textured soils. Treatments included five rates of B at three pH levels. Yields and B content of plants were measured. After the plants were harvested, soils were analyzed for water‐soluble B and pH. Results showed that alfalfa grown on the coarse‐textured soil had the highest uptake of B per unit of water‐soluble B in the soil and the plants from the fine‐textured soil had the least. The medium‐textured soil was intermediate. As the acidity decreased from a pH value of 5 to 7, less B was available at any level of water‐soluble B in all three soil types. These results indicate that texture and pH must be considered when water‐soluble B is used as a measure of availability to plants.
A Rapid Method for Measuring Lime Requirement of Red‐Yellow Podzolic Soils
Authors: Adams Fred , Evans C. E. 
Published: July 2010

AbstractThe exchangeable acidity determined by neutral 1N NH4OAc was compared to that measured in a buffered solution on 348 soil samples from profiles of Red‐Yellow Podzolic soils in Alabama. The soil pH values ranged from 4.1 to 6.5 and cation‐exchange capacities from 0.8 to 13.0 me. per 100 g. The methods measured comparable amounts of acidity. An equation was calculated by the method of least squares for the relationship between soil pH and percent base unsaturation for all samples. The amount of CaCO3 needed to bring soil pH to desired level was calculated by estimating percent base unsaturation from soil pH values in water and by measuring exchangeable acidity of soil by pH values in a buffered solution. The validity of this procedure was tested by incubating soils with increments of Ca(OH)2 and measuring the change in soil pH.
Determination of Phosphorus Fixation Capacity in Organic Soil
Authors: Harris C. I. , Warren G. F. 
Published: July 2010

AbstractIn a study of 15 organic soils the reduction in phosphorus concentration in aqueous solutions shaken with the soils gave a good indication of their phosphorus fixation capacities. An equally good indicator in soils that had had prior phosphorus fertilization was the level of water‐extractable phosphorus. Total iron, aluminum, calcium, and phosphorus content of the soils did not relate significantly to phosphorus fixation capacity.
Soil Morphology and Genesis at Higher Elevations of the Great Smoky Mountains
Authors: McCracken R. J. , Shanks R. E. , Clebsch E. E. C. 
Published: July 2010

AbstractProperties of soils representative of the elevation from 4,500 to 6,600 feet in the Smokies along the North Carolina‐Tennessee border are reported.Mean annual rainfall exceeds 80 inches. Mean air temperatures are: annual 45° to 49°F.; January, 31° to 35°F., July, 59° to 63°F. Parent rock is feldspathic sandstone and conglomerate. These soils can be placed in two groups: (1) lacking A2 horizons with thin A1 and “color B” horizons, and (2) with A2 horizons, Bir horizons, and relatively thick mor layers. Soils of the first group ordinarily occupy well‐drained sites under spruce‐fir forest. Those of the second group occupy less well‐drained sites under heath bald or rhododendron understory of sprucefir, with some indication that they tend to form from more quartzose conglomeratic rock.Soils of the first group are ascribed to the Sol Brun Acide great soil group on the basis of very low base status and high exchangeable Al, C/N levels, lack of relative accumulation of free iron and of layer silicates, and lack of A2 horizons. Second group soils are excluded from the Sol Brun Acide group, due to the presence of A2 horizons, differential iron accumulation, and C/N levels, and are interpreted as Podzols.Possible mechanisms are proposed to account for contrasting properties of the Sol Brun Acide and Podzol soils described, and the anomalous absence of A2 in the Sol Brun Acide of the Smokies. Extreme acid hydrolysis, producing intergradational three‐layer silicates plus kaolinite and gibbsite weathering end products, is postulated for these soils.
Occurrence of Chlorite‐Like Intergrade Clay Minerals in Coastal Plain, Piedmont, and Mountain Soils of North Carolina
Authors: Weed S. B. , Nelson L. A. 
Published: July 2010

AbstractSoils of the Coastal Plain, Piedmont, and Mountain regions of North Carolina were examined for the occurrence of chlorite‐like intergrade clay minerals. The intergrade clay minerals were found to be very common constitutents of soils examined, ranging in occurrence from trace to major amounts. Degree of interlayering, as estimated from response of clays to acid NH4F treatment, was related to position of the clay in the profile, usually, though not always, decreasing with depth. The amount of 3‐layer clay, as estimated by X‐ray diffraction, was greatest in the surface horizons and decreased with depth. For soils formed on similar parent material, 3‐layer clays from well‐drained, highly oxidized soils were usually more difficult to collapse than those from less oxidized soils. Chemical and mineralogical studies suggest that the intergrade clay minerals originated from mica precursors.
The Effect of Soil Saturation Upon the Dry Weight, Ash Content, and Nutrient Absorption of Various Bottomland Tree Seedlings
Authors: Hosner John F. , Leaf Albert L. 
Published: July 2010

AbstractCurrent year seedlings of 14 bottomland tree species surviving 60 days of completely water‐saturated soil conditions were compared to check seedlings grown under well‐watered but nonsaturated soil conditions. Comparisons were made of the following: dry weight per seedling top, and contents of ash, N, P, K, Ca, and Mg. Based on root and shoot growth and nutrient absorption, the species are grouped according to their relative tolerances to watersaturated soil conditions as follows: Tolerant—Nyssa aquatica, Fraxinus profunda, Salix nigra, Fraxinus pennsylvanica; Intermediate—Quercus palustris, Populus deltodis, Platinus occidentalis, Acer negundo, Acer rubrum, Acer saccharinum; Intolerant—Ulmus americana, Celtis occidentalis, Liquidambar styraciflua, Celtis laevigata.
A Comparison of Selected Methods for Expressing Soil Aggregate Stability
Authors: Conaway Andrew W. , Strickling Edward 
Published: July 2010

AbstractAggregate stability was determined on samples taken from plots under 10 cropping systems on a Beltsville silt loam and on samples taken from selected soil types in Maryland, North Carolina, South Dakota, Texas, and Wisconsin. Complete aggregate and mechanical analysis curves were determined on the 2.0‐ to 4.76‐mm. fraction from each soil sample. The method of Bryant et al. (2) was also used to determine water stability of this fraction.These data were used to calculate soil aggregate stability by 24 different methods. Duncan's multiple range test was used to determine the ability of each method to distinguish between changes in soil aggregate stability produced by the cropping systems.In general, simple summation fractions of the water‐stable soil aggregates distinguished well between cropping systems and were as sensitive as more time‐consuming methods. It was found that changes in aggregate stability were reflected most by the 0.5‐ to 2.0‐mm. aggregates.
Kinetics of Potassium Release from Biotite and Muscovite in Sodium Tetraphenylboron Solutions
Authors: Reed M. G. , Scott A. D. 
Published: July 2010

AbstractA mathematical expression that describes the release of interlayer K from mica particles in NaCl‐NaTPB solutions was derived. The mica particles were assumed to be circular discs and the rate determining process for the release of K was considered to be the simultaneous diffusion of K and Na within the particle. Therefore, this derivation involved the solution of a two‐dimensional radial diffusion problem in which K diffuses from a receding weathering front to the periphery of the particle.The validity of these assumptions and the resulting expression was evaluated with experimentally determined K release data. The experimental data were obtained with different size fractions of biotite and muscovite placed in NaCl‐NaTPB solutions for different periods of time. The results obtained with each size fraction were accurately described by the theoretical expression. In the case of a 50 to 62µ biotite fraction, this was true even though 90% of the K was released in a period of 113 hours. On the other hand, the expression did not account for the effect of particle size. A modification of the expression, based on the experimental results, however, accounted for the effects of both time and particle size.
Identification of Reaction Products from Phosphate Fertilizers in Soils
Authors: Lindsay W. L. , Frazier A. W. , Stephenson H. F. 
Published: July 2010

AbstractApproximately 30 crystalline phosphate compounds, in addition to colloidal precipitates of variable composition, were identified as reaction products following the addition of various fertilizer solutions to soils and soil constitutents. The identifications were made by means of X‐ray, petrographic, and chemical analyses. The findings help to clarify the mechanism of phosphate reactions in soils, which includes the dissolution of fertilizer and soil constituents and the precipitation of new products.
Comparative Rates of Decomposition in Soil of Wood and Bark Particles of Several Hardwood Species
Authors: Allison Franklin E. , Murphy Raymond M. 
Published: July 2010

AbstractThe decomposition rates of the finely‐ground woods and barks of 9 species of hardwoods were determined in the laboratory at two nitrogen levels. Carbon dioxide was measured at frequent intervals during periods varying from 72 to 580 days. The following species were studied: black oak, white oak, red oak, post oak, hickory, red gum, yellow poplar, chestnut, and black walnut. During the first 60 days an average of 30.3% of the wood carbon was released as CO2 in the absence of fertilizer nitrogen, and 45.1% was released in its presence; the corresponding values for the barks were 22.4 and 24.5%. The variations in the rates of CO2 release from the woods were not great, but hickory and black walnut barks decomposed much slower than the other barks. The hardwoods were attacked much more readily than most of the softwoods used in an earlier study, and consequently more nitrogen was required by the microorganisms that decomposed them. There were no indications that any of these wood products was toxic to the decay organisms.
Factors Responsible for Poor Response of Corn and Grain Sorghum to Phosphorus Fertilization: II. Lime and P Placement Effects on P‐Zn Relations
Authors: Langin E. J. , Ward R. C. , Olson R. A. , Rhoades H. F. 
Published: July 2010

AbstractSoil factors controlling Zn concentration in the corn plant are very complex, including among others a beneficial action of applied N and a detrimental action of P or lime inherently present or added to the soil. It is apparent that Zn deficiency is likely to be aggravated or created by row application at low rates or heavier mixed applications of readily available P fertilizer. The problem is greatest on soils that are calcareous and especially on those of high inherent P supply where plant Zn concentration already may be approaching a critical level.The more effectively the applied P is utilized by the crop, the more severe is the reduction in Zn utilization. Thus the calcareous soil with tendency for Zn deficiency perhaps should not be treated so as to afford maximum early uptake and utilization of applied P. It also seems evident that low P rates rather than heavy, infrequent applications are likely to give less damaging effects. Alternative to these procedures is to apply supplemental Zn whenever P is added to soil where the level of Zn availability is uncertain.The damaging effect of P on Zn utilization is considered to be largely physiological in nature, probably a plant root cell absorption phenomenon, and not an external Zn phosphate precipitation. It is recognized, however, that root proliferation in the band of row‐placed P may be a contributing factor due to inadequate exploration of a soil body where enough available Zn may exist.
Controlled Release of Fertilizer Minerals by Incapsulating Membranes: II. Efficiency of Recovery, Influence of Soil Moisture, Mode of Application, and Other Considerations Related to Use
Authors: Lunt O. R. , Oertli J. J. 
Published: July 2010

AbstractIt was shown using membrane‐coated granular fertilizer, in which the membrane constituted 11 or 12.5% of the weight of the granules, that: (a) moisture levels, exceeding the range of permanent wilting percentage to field capacity in a loam soil, did not appreciably affect the rate of transfer of minerals through the membrane of coated fertilizer mixed in the soil, (b) the time for transfer of a given fraction of fertilizer through membranes is substantially extended if the fertilizer is topdressed on a soil as compared to incorporated (presumably due to intermittent drying between leachings), and (c) an efficiency of recovery ranging from about 25 to 45% was obtained from a single application, incorporated in the sand, of coated ammonium nitrate by corn during a 3‐month growing period. In the latter study a sand was used containing < 1% of clay and as much as 7 feet of water passed through the root zone during the period of the study. Implications of the coating technique for controlling fertilizer availability are briefly considered.
Weathering of Sodium‐Potassium Mica in Soils of the Virginia Piedmont
Authors: Cook M. G. , Rich C. I. 
Published: July 2010

AbstractThe occurrence of paragonite, the Na‐analogue of muscovite, in intimate association with muscovite was observed in two soils and their parent materials in the Virginia Piedmont. A relatively constant Na/K molar ratio of approximately 1 was maintained in both the parent rocks and soils. This indicated that equal molar quantities of paragonite and muscovite were present and that the weathering rates of the two micas were similar.Vermiculite and kaolinite were the weathering products formed upon weathering of the mixed Na‐K mica. The vermiculite had the same expansion and contraction characteristics as that formed from a predominantly K‐mica. Consequently, the kind of weathering of muscovite and paragonite also appears to be similar.Paragonite is believed to be of more widespread occurrence than previous work has indicated. Its possible influence on soil genesis, morphology, and classification may be significant.
Aluminum Bonding in Soils: a Unifying Principle in Soil Science
Authors: Jackson M. L. 
Published: July 2010

AbstractThe aluminum ion bonds through oxygen to form a variety of functional groups underlying diverse properties of soils. One aluminum‐bond functional group provides the cation exchange site of soil layer silicate clays. Pauling's m‐rule of acid strength for oxy‐acids, (HO)nOmC, applied to the 2:1 layer silicate clay formula of beidellite, considering all structural cations, yields m = 1.6, characteristic of a medium to strong acid strength (on an m‐scale: 1 = weak; 2 = strong). The solubility product of Al(OH)3, k1 of Al(OH2)63+, and the Pauling k1/k2 ratio of 105 are applied to calculate concentrations of aluminohydronium monomeric cation species of valence of 3, 2, and 1. These concentrations relate to cation exchange and interlayer aluminum polymerization reactions in soils during chemical weathering. The latter and mineral colloid composition changes are summarized in the generalized bonding equation: Al ‐ O ⇌ Al ‐ OH, which provides the ultimate buffer, setting the lower and upper limits of the pH range of soils except in the presence of strong acidforming compounds such as S and FeS2. Aluminum bonding is central to soil acidity, through not only the acidic aluminohexahydronium monomeric cations, but also through the weakly acid Al‐OH2 … OH pair at edges of polymerized (“precipitated”) hydroxy aluminum structures. The aluminum toxicity of soil acidity may involve aluminum bonding and solubility product relations at the soil‐root interface and in solutions in soil and sap. Retention by soils of anions such as phosphate and sulfate is closely related to aluminum bonding of these anions (OH replacement). Some aspects of soil aggregate structure involve hydroxy aluminum bonding; loss of aggregates follows intensive cheluviation in the A2 horizon. Aluminum bonding in a real sense supplies a unifying principle for understanding many properties of the soil system, much as hydrogen bonding has served to unify understanding of many properties of water and of aqueous organic systems including living matter.