bluuebunny/crossref_metadata_2025_split huggingface dataset:
Soil‐Erodibility Evaluations for Soils on the Runoff and Erosion Stations
Authors: Olson Tamlin C. , Wischmeier W. H. 
Published: July 2010

AbstractThe universal soil‐loss estimating equation introduced by Wischmeier is:A = R K L S C Pwhere A is estimated soil loss, R is the rainfall‐erosion index, K is the soil‐erodibility factor, and L, S, C, P are factors for length and percent slope, cover, and mechanical conservation practices, respectively.The soil‐erodibility factor (K) is defined as the average soil loss per unit of the erosion index (R) from continuous fallow on a plot 72.6 feet long on a 9% slope. The value of this factor was approximated for 20 soil types represented on the U. S. Department of Agriculture runoff and erosion research stations located in the eastern half of the United States.The estimated values were computed from the plot data, using those plots whose conditions most closely approximated base conditions of cover and geometry. Observed soil losses from cropped plots were adjusted to fallow conditions by use of previously published numerical values of C and P.The resulting table of K values provides a list of bench‐mark values for estimating the erodibility of other soils.
Ion Sorption by Soil Separates and Exchange Equilibria Involving Sodium, Potassium, and Rubidium
Authors: le Roux F. H. , Coleman N. T. 
Published: July 2010

AbstractSodium‐potassium exchange reactions were studied with four California soils, utilizing chromatographic and equilibrium procedures. Apparent exchange constants varied with ion saturation and indicated a larger affinity for potassium as its equivalent fraction on exchange sites decreased. This was especially true for soils containing biotite‐hydrobiotite‐vermiculite in the coarse fractions. Clay and silt‐size materials from such a soil were packed into columns, and the sorption‐desorption behavior of rubidium was measured using the radioisotope Rb86. Irreversible sorption of rubidium with corresponding reductions in cation‐exchange capacity was large for silt, intermediate for coarse clay, and negligible for fine clay. Sodium‐rubidium exchange isotherms obtained for various size fractions both before and after a portion of the exchange‐capacity was “blocked” with Rb or K indicated a quite specific sorption of Rb on certain sites, with “normal” ion‐exchange behavior for the remainder of the CEC. X‐ray diffraction studies suggested specific sorption of K and Rb by vermiculite and hydrobiotite, irrespective of the Na/K or Na/Rb ratio in saturating solutions. However, even when sites with specific affinity for Rb or K were eliminated, there was significant variation in the apparent exchange constants obtained for different soils. For soil containing vermiculite in the coarse fractions, the specific sorption of radiorubidium may be a conveniently determined guide to potassium fertilizer needs.
Gibbsite Formation From Aluminum‐Interlayers in Montmorillonite
Authors: Barnhisel R. I. , Rich C. I. 
Published: July 2010

AbstractGibbsite crystallized from hydroxy‐Al which previously had been precipitated on the interlayer surfaces of the 2 to 0.2µ fraction of montmorillonite. Hydroxy‐Al interlayers were prepared with OH/Al molar ratios of 0.38, 0.75, 1.50, 2.25, and 3.00 and were aged 1, 3, and 6 months. In the samples that were not aged, the CEC decreased from 78 to 2 me. per 100 g. as the OH/Al molar ratio increased. In addition, the basal spacing increased from 10.2 to 14.7Å. (K‐saturated, 300°C.) as the OH/Al molar ratio increased.X‐ray diffraction, thermo‐gravimetric, and differential thermal analysis studies indicated that the hydroxy‐Al interlayers formed with OH/Al molar ratios of 0.38, 0.75, and 1.50 were stable when aged 6 months; whereas, samples with OH/Al molar ratios of 2.25 and 3.00 were not. Gibbsite formed after 1 month in the sample with an OH/Al ratio of 3.00 and after 3 months in the sample with an OH/Al ratio of 2.25, and the amount of gibbsite increased with time. Gibbsite formed in the presence of montmorillonite at a pH of < 4.3. After the Al‐interlayers were removed through gibbsite formation, the montmorillonite regained its cation‐exchange capacity. The crystallization of gibbsite from Al‐interlayers may be one mechanism for the formation of this mineral in some acid soils.
Effect of Anions on Amount of Sodium Adsorbed by Sodium‐Saturated Utah Bentonite
Authors: Sommerfeldt Theron G. , Peterson H. B. 
Published: July 2010

AbstractSodium‐saturated Utah bentonite was equilibrated in various concentrations and kinds of sodium salt solutions to ascertain the effects of different anions in the system on the amount of sodium adsorbed by the clay. Effects of pH on the adsorption of sodium were also studied by equilibrating the clay in solutions having pH's of 7.2 and 10.5. The solutions were analyzed before and after equilibration to determine their changes in ion concentrations and pH. Soluble silicon was determined in both the equilibrate and the cation extraction solutions.The clay proved sensitive to its anion environment. The amount of sodium adsorbed by the clay and the concentration of the soluble silicon in the equilibrate varied with the anion present. Increased concentration of anion generally increased the anion effect. After equilibration in solutions having an ionic strength of 1.0, the amount of sodium adsorbed was 66, 68, 76, 77, 94, and 115 me. per 100 g. of clay when the anions were bromide, iodide, chloride, sulfate, bicarbonate, and hydroxide, respectively. A correlation existed between the final pH and the amount of sodium adsorbed; generally the amount adsorbed increased with pH. A correlation also was evident between the amount of soluble silicon and final pH.
The Release of Fixed Ammonium from Soils by Sodium as Affected by Small Amounts of Potassium or Ammonium
Authors: Leggett G. E. , Moodie C. D. 
Published: July 2010

AbstractThe release of fixed NH4 from soils by Na was studied. Data are presented to show that when no K was added to NH4‐saturated air‐dried soils, 86 to 98% of the fixed NH4 was released during alkaline aeration or distillation. When small amounts of K were added to the alkalizing agents, the release was markedly decreased. When the K/Na ratio of the alkalizing agents was increased to 0.005, only 14 to 35% of the fixed NH4 was released. Similar effects were noted when small amounts of NH4 were allowed to accumulate in the system during equilibration of NH4‐saturated soils in various volumes and concentrations of NaCl solutions.The rate of release of fixed NH4 was studied by aerating NH4‐saturated soils in the presence of Na2CO3 solution. The data obtained indicate that release is slow, even under conditions which favor removal of the released NH4 from the system. A linear relationship was obtained when the logarithm of rate of release was plotted against time. Thus, it was concluded that the release of fixed NH4 was similar to the release of fixed K from vermiculite and the later stages of K release from biotite noted by others.
The Availability of Fertilizer Nitrogen Immobilized During Decomposition of Straw
Authors: Stewart B. A. , Johnson D. D. , Porter L. K. 
Published: July 2010

AbstractA greenhouse study measured the extent to which fertilizer N15 immobilized during decomposition of straw becomes available for plants. Less than one‐half of the immobilized fertilizer N15 was released for plant uptake during four successive croppings in the greenhouse. The crops were beets, barley, and two of corn.Fractionation of the soil N showed that about 75% of the N taken up by the plants was derived from the nondistillable acid‐soluble N fraction. Fertilizer N15 immobilized in this fraction was utilized at a faster rate by plants than the N initially present in this fraction.
Sequence of Products Formed During Denitrification in Some Diverse Western Soils
Authors: Cooper Grant S. , Smith R. L. 
Published: July 2010

AbstractThe sequential products of anaerobic denitrification were determined on seven Western soils (four alkaline, two acid, and one neutral) by soil and gas analysis. The soils with 1% alfalfa and added KNO3 were incubated at moistures slightly greater than field capacity and with an atmosphere of He. The soils and gases were periodically analyzed and balance sheets prepared. The sequence of NO3‐ → NO2‐ → N2O → N2 operated in all soils. The N2O and N2 were determined on a gas chromatograph. The rates of nitrogen interchanges and maximal amounts of nitrite, N2O, and N2 were determined. From this data it was postulated that the rate‐limiting process for denitrification in acid soils is the reduction of nitrate, while in alkaline soils it is the reduction of nitrite. The reduction of N2O was rapid in all instances. The total time for complete reduction of 300 ppm. N as nitrate to N2 at 30°C. varied only from 28 to 96 hours for the 7 soils. Lowering the temperature to 25° or 20°C. influenced all rates for 3 alkaline soils and resulted in a twofold increase in denitrification time for the 10°C. drop. Decreases in initial concentration of added KNO3 to 150, 75, and 37.5 ppm. did not change the overall rate of dentrification. There was, however, a marked reduction in the maximal amounts of N2O found in the gaseous atmosphere when the initial KNO3 concentration was reduced.
Influence of Salts on Ammonium Oxidation and Carbon Dioxide Evolution from Soil
Authors: Johnson D. D. , Guenzi W. D. 
Published: July 2010

AbstractOsmotic tension was found to reduce nitrate production and CO2 evolution from soil in a linear manner. This is essentially the result which would have been predicted using principles derived from studies on the influence of salts on the growth of higher plants. Nitrification showed the influence of individual salt species, with NaCl being the most toxic. Total microbial activity, as measured by CO2 evolution is much more tolerant of osmotic stress and shows no definite individual salt effects.
The Effects of Nitrogen on Short‐Term Phosphorus Absorption and Translocation in Corn (Zea Mays)
Authors: Cole C. V. , Grunes D. L. , Porter L. K. , Olsen S. R. 
Published: July 2010

AbstractShort‐term P uptake studies were conducted with intact 1‐month‐old corn plants of differential N and P composition. Supplemental N pretreatments producing increased growth rates and higher levels of N in the plant stimulated the rate of P uptake per unit dry weight of root more than did a tenfold increase in P concentration in the external solution. Nitrogen pretreatments caused five‐ to tenfold increases in rate of P translocation to the tops during the uptake period. The presence of nitrate or ammonium ions in the test solution during the uptake period had negligible effects on P uptake rates. Phosphorus uptake rates were highly correlated with total N level in the roots. The stimulation of P uptake rates with higher plant N levels suggests a connection between N metabolism and P uptake processes.
Physical Characteristics of Four Mississippi Soils
Authors: Andrew L. E. , Stearns F. W. 
Published: July 2010

AbstractFour silt loam soils in Warren County, Mississippi, were studied intensively to determine to what extent a soil series, as normally mapped by types, delimits the physical properties of the surface foot.The degree of variation between individual samples implied that intensive sampling is necessary to typify physical properties of these soils. Means differed significantly between series in clay content, bulk density, and moisture‐tension values. However, the range in values suggests that, for strength classification and simliar purposes depending upon physical properties, similar textural types in different series can often be combined.Memphis and Loring, designated upland soils, had considerably more clay than the bottom‐land soils Falaya and Collins. As a result of erosion, variation in clay content in the plow layer was far greater in upland than in bottom‐land soils.
Soil Variability—A Serious Problem in Soil‐Site Studies in the Northeast
Authors: Mader Donald L. 
Published: July 2010

AbstractThe degree of variability and its effect on accuracy of mean plot values for soil properties is an important problem needing evaluation for soil‐site studies in the Northeast. This paper discusses the variability in soils sampled in a red pine plantation site study. Two profiles were sampled by horizon on each plot. Data are presented on the following soil properties: organic matter, N, silt and clay, exchangeable Ca plus Mg, cation‐exchange capacity, and bulk density. Variability between plots was much greater than within plots. Some soil properties required a large number of samples for accurate estimation, others a small number. Variation did not differ greatly from A to B horizons.
Site Evaluation Studies in Red Pine Plantations in Michigan
Authors: van Eck W. A. , Whiteside E. P. 
Published: July 2010

AbstractSoil productivity for planted red pine in lower Michigan was evaluated for 27 soil series in terms of dominant tree height at age 50 by aid of local site curves developed from actual growth measurements.In the presence of soil factors favoring adequate soil moisture supply and in the absence of soil factors which limited effective soil depth, the site index and growth rate of red pine was found to be rather uniform for many coarse‐ and moderately coarse‐textured soils.The inadequacy of a single set of site curves for the prediction of site productivity is discussed and separate sets of curves are presented for soils causing growth patterns deviating from the normal trend.The observed variations in height growth are associated with even greater relative differences in volume of wood produced. While variations in the quality of the wood products are also important in evaluating the productivity of forest sites, this aspect was not covered in the present study.
The Influence of Crop Environment on the Internal Water Balance of Cotton
Authors: Namken L. N. 
Published: July 2010

AbstractThe relative turgidity of cotton plants subjected to three soil moisture levels was related to soil moisture content, air temperature, pan evaporation, vapor pressure deficit, and air movement. A multiple regression equation that contained only those variables significant at the 1% level of probability was developed. The influences of vapor pressure deficit and air movement were not significant at the 1% level. Soil moisture, ambient temperature, and pan evaporation accounted for 87.5% of the variation in the relative turgidity of cotton leaves. Soil moisture alone accounted for 70.9% of the variation with a reduction to 44.3% upon discounting the effects of ambient temperature and pan evaporation. Ambient temperature and pan evaporation accounted for 43.1% of the variation with a reduction to 16.5% upon discounting the effect of soil moisture. The results demonstrate the relative importance of soil moisture and atmospheric conditions in regulating the internal water balance of plants.
Comparative Studies of Actinomycete Populations in Acid Podzolic and Neutral Mull Forest Soils
Authors: Corke C. T. , Chase F. E. 
Published: July 2010

AbstractA comparison has been made of the actinomycete populations of acid podzol and neutral mull soils under forest cover. In both soils, numbers decreased with depth though less rapidly than did the combined bacteria and fungi; consequently the actinomycetes were, proportionately, slightly more numerous in the lower mineral horizons. The actinomycetes in the podzol were more acid tolerant than those from the mull soils. Approximately two‐thirds of the isolates from the podzol grew at pH 4.5 and one‐third at pH 4.0. Of the isolates from the mulls, only one‐sixth were capable of growth at pH 4.5 and none grew at pH 4.0. Furthermore, the acidic environment restricted actinomycete development to from five to seven “species groups” of Streptomyces.
Soil Parameters for Evaluating Tillage Needs and Operations
Authors: Larson W. E. 
Published: July 2010

AbstractEstimated critical limits of selected soil parameters for evaluating tillage requirements for corn in the water management (interrow) zone and seedling environment (row) zone are presented. Suggested parameters for corn in the western Cornbelt for the row zone include soil temperature, secondary aggregate size, bulk density and volume of the zone. For the interrow zone, the parameters include depression storage, plow layer storage, and/or surface mulch or surface microrelief. The research basis for the selection of the critical limits and soil parameters is discussed. This approach can be used to evaluate tillage needs for other crops.
Distribution Patterns of the Weld‐Rago Soil Association in Relation to Research Planning and Interpretation
Authors: Fly Claude L. , Romine Dale S. 
Published: July 2010

AbstractThis study is concerned with criteria for predicting applicability to other soils of research results obtained from key or benchmark soils. Soil‐water‐plant growth relations which affect yields under different levels of management were evaluated at Akron, Colo. Under 46 years of uniform management, wheat production levels varied from 73 to 120 among eight soil types identified in a 25‐acre test field formerly mapped as one soil type. Soil differences induced wider variations under uniform treatment than did different treatments on a single soil type. When the detail of delineation and characterization of soils is comparable to the detail of the research plot layout, existing research fields and plot data may be used to associate soil qualities with response to treatment. The reliability of application of research findings to other areas will depend on adequate characterization and evaluation of the soil in each plot.
Influence of Hydroxy Aluminum Ions on pH Titration Curves of Hydronium‐Aluminum Clays
Authors: Schwertmann U. , Jackson M. L. 
Published: July 2010

AbstractVermiculite (particles 2 to 0.2 microns in diameter), after being treated with H‐Amberlite IR‐120, aged for 97 days, and suspended in 1N KNO3, showed a third buffer range between pH 5.5 and 7.6 on continuous titration with dilute NaOH. This third buffer range is attributed to neutralization of excess protons of Al‐OH2 groups in positively charged hydroxy aluminum polymers formed on interlayer surfaces of vermiculite under the influence of their negative charge. This conclusion was reached on the basis of observance of the same additional buffer range in titration curves of partially neutralized and aged AlCl3‐solutions (OH/Al ratios ranging from 1 to 2.25) and of vermiculite treated with the aged hydroxy aluminum solutions. The hydroxy aluminum polymers are only partly exchangeable by 1N KCl, and also are fairly resistant to treatment of the clay with H‐resin. The X‐ray diffractogram of the vermiculite shows an enhanced 7.2Å. (002) peak after H‐resin treatment and aging, indicating more interlayer material. Hydroxy aluminum treated vermiculite and aged acid vermiculite showed reduced collapsibility on K saturation and heat treatment, pointing also to the occurrence of the hydroxy polymers in the interlayer position. Compared with similar reactions with montmorillonite from bentonite previously reported, these compounds form with greater avidity in vermiculite, have a greater stability to subsequent H‐resin treatment, and have a higher resistance to exchange in KCl. These differences presumably arise because of the higher net negative charge of the vermiculite layers. Soil clays which give X‐ray diffraction evidence of interlayer hydroxy aluminum show the third buffer range on treatment with H resin, without aging time or treatment with hydroxy aluminum solutions.
Lime Requirement Related to Physical and Chemical Properties of Nine Michigan Soils
Authors: Ross G. J. , Lawton K. , Ellis B. G. 
Published: July 2010

AbstractLime requirement of 9 Michigan soils was determined by incubating the soils for 13 weeks in the greenhouse after addition of varying rates of agricultural limestone. The initial pH of all soils was approximately 5.5. Lime requirement was correlated with cation‐exchange capacity, organic matter content, exchangeable hydrogen per 100 g. soil, clay content, and lime requirement measured by the Shoemaker, McLean, and Pratt buffer method. Increase in soil pH after liming was significantly correlated with increase in percent base saturation within each soil type, but not between soil types. Liming did not appreciably affect the amount of exchangeable Mg and K or extractable P in the soils. At pH 5.5, liming increased yield of alfalfa on 6 soils, but not on the remaining 3 soils. Low yields were correlated with low calcium content in the plants.
A Soil Test for Phosphorus Based Upon Fractionation of Soil Phosphorus: I. Correlation of Soil Phosphorus Fractions with Plant‐Available Phosphorus
Authors: Al‐Abbas A. H. , Barber S. A. 
Published: July 2010

AbstractThe forms of P in 24 soils were determined by chemical fractionation. The available P was determined by plant growth experiments. Regression analysis of the P fractions with available P showed that iron P explained most of the variation. Water‐soluble P was the only other fraction significantly contributing to the explained variation.
The Residual Effect of Zinc Applied to Soils
Authors: Brown A. L. , Krantz B. A. , Martin P. E. 
Published: July 2010

AbstractGreenhouse tests with sweet corn were studied to measure the residual effect of soil applied Zn.Of the six soils, four had been shown to be Zn deficient by previous tests. Ten successive crops were grown in these soils to which had been applied, 0, 4, and 20 mg. Zn per 1,600 g. of soil.Dry weight yields showed that the 4‐mg. Zn rate was adequate for 6 or 7 successive crops; the pots to which 20 mg. was added were not in the deficient range even after 10 crops. The two soils that were not deficient produced 10 crops without any deficiency symptoms developing or any growth response to the Zn applications.Dithizone‐extractable soil Zn decreased gradually with cropping. When the values dropped below 0.55 ppm, there was a plant growth response to Zn.Alfalfa was found to obtain adequate Zn from soils which were inadequate for sweet corn.
Early Growth of Corn as Affected by Soil Temperature
Authors: Allmaras R. R. , Burrows W. C. , Larson W. E. 
Published: July 2010

AbstractCorn growth was measured in 23 location‐years in the eastern United States, where an average soil temperature reduction of 2.2°F. at the 4‐inch depth was obtained by a straw‐mulch treatment as compared to unmulched treatments during the first 6 weeks following planting. For soil temperatures ranging from 60° to 83°F., the ratio of the dry matter produced on the mulched treatment to that produced on the unmulched treatment was linearly related to the 4‐inch soil temperature. The validity of this linear relation was supported by data from experiments in the greenhouse and laboratory where growth of corn was observed under carefully controlled temperatures. For field conditions, a corn growth vs. soil temperature relation was constructed from the above linear relation, and the estimated optimum soil temperature for corn growth (dry matter production) was 81.3°F.The effect of soil temperature on four different growth measurements (height, dry matter production, yield of N, and yield of K) of corn was different for each growth measurement in both the field and the greenhouse.