bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Humic Acids on Nodulation and Dry Matter Production of Soybean, Peanut, and Clover
Authors: Tan K. H. , Tantiwiramanond D. 
Published: July 2010

AbstractHumic substances have been reported to increase plant growth. A stimulating effect on the growth of legumes may improve biological nitrogen fixation in soils. The present investigation studied dry matter production, nodulation and N content in nodules of soybean (Glycine max L., ‘Bragg’), peanut (Arachis hypogaea L., ‘Florunner’), and clover (Trifolium vesiculosum, ‘Arrow leaf’), grown in sand cultures containing a fertilizer mixture and 0 to 800 mg kg−1 (ppm) of fulvic acid (FA) or humic acid (HA). The results indicated that FA and HA were capable of stimulating dry matter production in the plants. Dry weights of roots and nodules showed a tendency to increase over the control at 100 to 400 mg kg−1 (ppm) of FA or HA. The increases in total dry matter production were statistically significant at 800 mg kg−1 (ppm) of FA or HA, and a positive correlation was noticed between increases in dry weights of shoots, roots, and nodules and FA and HA concentrations. Fewer nodules were produced by plants receiving FA and HA treatments than the control, but the nodule mass was greater with the FA and HA treatments. The N content of nodules was little affected by the treatments, although a tendency can be noticed that 100 mg kg−1 (ppm) of FA had decreased the N content in the nodules of both soybean and peanut plants.
Effect of Pelleting, Temperature, and Soil Type on Mineral Nitrogen Release from Poultry and Dairy Manures
Authors: Hadas Aviva , Bar‐Yosef B. , Davidov Sara , Sofer M. 
Published: July 2010

AbstractPellets are produced from manures for more convenient and economical use. The rate of N mineralization of manures under different conditions is of agronomic importance, since it allows estimation of mineral N supply to plants as a function of time. Pelleted manure may have mineralization characteristics differing from those of its raw components due to the high temperatures and pressure involved in the pelleting process. The rate of N mineralization of raw manures and pelleted manure was studied in water and in soil incubation experiments. About 10% of total N in the manures was initially KCl‐extractable NH4. Within 1 d, 30 to 35% of total N in poultry manure and 18% in mixed 75% dairy and 25% poultry manure were mineralized in water. Mineralization kinetics of manures in soil showed an initial rapid process followed by a slow release of mineral N and could be described as two simultaneous first‐order reactions. During the first week, 34 to 44% of total N in poultry manure and 14 to 23% in 75% dairy + 25% poultry manure were mineralized in soil pellets releasing more N than ground manures. After 2 to 3 months, mineral N in soil was 34 to 50 and 27 to 44% of total N in poultry and 75% dairy manures, respectively, the pellets contributing equal or less mineral N to soil than the ground manures. Pelleting increased the relative amount of rapidly mineralizable N in the manures and created higher NH4‐N concentrations in soil, which under less favorable conditions for nitrification increased the susceptibility to loss of NH3‐N. Temperatures in the range of 14 to 35°C had little effect on the rate of mineralization but affected N loss from poultry manure pellets by delaying nitrification at 14 and 35°C compared with 25°C.
Albic Neoskeletans in Argillic Horizons as Indices of Seasonal Saturation and Iron Reduction
Authors: Vepraskas M. J. , Wilding L. P. 
Published: July 2010

AbstractSignificant periods of seasonal waterlogging in some soils of the Texas Coastal Plain have gone unrecognized because the soils lack low (≤ 2) chroma colors. A study was conducted in two soils along a forested toposequence of Alfisols to identify morphological features other than color that are indicative of ground water saturation and Fe reduction. The duration of saturation and Fe reduction had been determined previously for each soil of the toposequence. Iron nodules (> 2 mm diam) and neocutanic albic materials (albic neoskeletans) were sampled and their abundance determined. Albic neoskeletans were also characterized with respect to total Fe content, particle size distribution, and color. Sesquioxide nodules within portions of the argillic horizon had no consistent relationship to the soil structure and were found both in zones of Fe loss and accumulation. This indicated at least some nodules were relict features and that nodules could not be used for moisture regime identification in these soils. Albic neoskeletans along ped surfaces and root channels formed in place by a loss of clay and free Fe from the surfaces of macropores. Most albic neoskeletans were not overlain by other cutans and all evidence indicated they formed under the current moisture regime in each soil examined. Albic neoskeletan abundance was directly related to the duration of Fe reducing conditions, but not to the duration of saturation. Greatest development of these features occurred in a soil with a perched water table in horizons that were Fe reduced for 55 to 146 d. It is suggested that albic neoskeletans be used as diagnostic criteria for water saturation and Fe reduction despite their moist color chromas of 4 or less. It is proposed that albic neoskeletans be used, when low (≤ 2) chroma colors are absent, to identify aquic intergrades in Paleudalfs.
Tillage and Surface Residue Effects on Soil Upper Boundary Temperatures
Authors: Gupta S. C. , Larson W. E. , Linden D. R. 
Published: July 2010

AbstractThe effects of tillage‐surface residue interactions on soil upper boundary temperatures are described. Regression curves are developed between the maximum and minimum soil surface temperatures vs. maximum and minimum air temperatures at the 2‐m height. Soil surface temperature variations between various residue and tillage treatments were mainly due to the change in surface residue cover. During fall and spring, the maximum temperature differences were 12 and 19°C, respectively, between no residue and surface residue treatments for the same tillage condition. Soil surface temperature variation due to the disturbance of soil by tillage for the similar residue cover condition were relatively small. During the growing season, maximum and minimum soil surface temperatures under corn canopies were approximately the same for all tillage‐residue interactions. A procedure to normalize diurnal upper boundary temperatures with respect to daily maximum and minimum soil surface temperatures is suggested. This procedure simplifies the upper boundary temperature data for easy comparison between treatments, seasons, and locations. Comparison of the average normalized soil surface temperature curves suggests that the shape of the daily soil surface temperature curve is slightly different for various tillage and residue interactions, with and without a corn crop. These differences in the average normalized soil surface temperature curves suggest that residue cover delays cooling more than heating of the soil surface. Based on the regression and the average normalized soil surface temperature curves, a procedure is described to estimate the soil upper boundary temperatures for various tillage and surface residue conditions from daily maximum and minimum air temperatures. Application of these soil upper boundary temperatures is in the physically based soil temperature models to estimate the root zone soil temperatures for various tillage and residue management systems with and without a corn crop.
Irrigation Decisions Simplified with Electronics and Soil Water Sensors
Authors: Cary J. W. , Fisher H. D. 
Published: July 2010

AbstractTwo simple, inexpensive systems use electrical resistance measurements to provide useful, immediate information to assist decisions made on irrigation water application. In one system a microprocessor‐based circuit coupled to a programmable calculator provides an on‐site estimate of the time until the next irrigation will be required, based on field data and an operator‐supplied parameter. The second system simply signals the arrival of the wetting front at any location in the soil by giving a visual indication, such as raising a mechanical flag. The microprocessor‐based circuit measures and stores the resistance of four gypsum blocks once a day. The program in the portable calculator accesses this information and uses it to extrapolate the soil drying rate to predict the number of days until the next irrigation. By restricting the microprocessor circuit to data acquisition only and putting all number‐handling routines into the calculator program, the cost and complexity of the microprocessor circuit is minimized, whereas maximizing the programming flexibility. This makes it feasible to install a number of these devices at different locations, all serviced by the same portable calculator.The water infiltration circuit intermittently scans eight sets of stainless steel electrodes to locate the soil wetting front during irrigation. When the resistance across the electrodes decreases, signaling the arrival of the front, the circuit trips a spring‐loaded flag. This provides a visible sign that the wetting front has reached that point in the soil. The equipment worked well. When irrigation was required in six or fewer days, the microprocessor/calculator system made correct predictions 85% of the time. An example of how easily any irrigation scheduling method may be converted to the microprocessor/calculator system is presented.
Probability Sampling Techniques for Estimating Soil Erosion
Authors: Roels J. M. , Jonker P. J. 
Published: July 2010

AbstractData on the lateral variability of soil loss from Submediterranean rangelands are presented. Modified Gerlach troughs were used to measure both rill and interrill erosion. Random, systematic, stratified random, and cluster sampling methods were tested for various numbers of plots and plot widths in order to find the method that gives the most accurate estimate of soil loss. If both the rill and interrill subpopulations are sampled, random sampling and stratified random sampling give almost identical standard errors. Cluster sampling yields larger errors and is therefore less effective. Systematic sampling, however, allows one to choose more accurate samples of an economical size, but its efficacy depends largely on the number of rills in the study area. The smallest standard errors are obtained by measuring the total rill erosion and by sampling only the interrill subpopulation. When this procedure is applied, the four sampling methods turn out to be equally accurate.
Iron Oxides in Petroferric Materials
Authors: Ibanga I. J. , Buol S. W. , Weed S. B. , Bowen L. H. 
Published: July 2010

AbstractSamples of petroferric materials with a very wide range of chemical and morphological characteristics were obtained from Australia, Bolivia, Brazil, Nigeria, Thailand, and the USA. A prominent feature of all samples is a high content of Fe and/or Al oxides, relative to other constituents. Free Fe oxide is present mainly as goethite or hematite with very small amounts of lepidocrocite in some samples. Soil sample color is related to the Fe oxide mineralogy; the reddish colored samples have a high content of hematite while the yellowish samples have a high goethite content. Also, samples with a low active Fe ratio tend to have a reddish color while those with a high active Fe ratio are yellowish in color. The active Fe ratio is not predictable from a knowledge of the crystallinity or particle size of goethite present, but the presence of lepidocrocite generally increases the oxalate‐extractable Fe. Both hematite and goethite in the samples contain Al up to about 25 atom percent. Treatment of the samples with boiling 5M NaOH decreased the Al‐content of some but not all hematites and goethites.
Stability Relationships in Kaolinite, Gibbsite, and Al‐hydroxyinterlayered Vermiculite Soil Systems
Authors: Karathanasis A. D. , Adams Fred , Hajek B. F. 
Published: July 2010

AbstractThe stability of common soil minerals found in Ultisols was studied relative to their natural soil solution composition. The mineralogy of the clay fraction (<2 µm) ranged from 22 to 60% in kaolinite, 0 to 20% in gibbsite, 17 to 57% in hydroxyinterlayered vermiculite (HIV), and 1 to 12% in quartz. Ion activity functions (pH‐⅓pAl and pH4SiO4) of soil solutions plotted on a stability diagram along with solubility lines of soil kaolinite, gibbsite, and HIV with the formula K0.24Ca0.08(Si3.24Al0.76)(Al1.56Fe0.24Mg0.20)[Al1.45(OH)3.79]O10(OH)2 indicated all solutions to be supersaturated with respect to reference kaolinite. Only a few surface soils containing gibbsite had solutions oversaturated relative to gibbsite. Solubility products of HIV were very close to its estimated pk, indicating a near‐equilibrium condition with this mineral, especially in eluviated and transitional subsoil horizons (E and EB). Although the HIV appeared to be metastable relative to reference kaolinite, the data indicated a possible equilibrium coexistence of the two minerals with an HIV stability field below or above that of soil kaolinite, depending on the degree of Al‐hydroxyinterlayering.
Submersible Pressure Outflow Cell for Measurement of Soil Water Retention and Diffusivity from 5 to 95°C
Authors: Constantz Jim , Herkelrath W. N. 
Published: July 2010

AbstractA technique was developed to measure water content in soil as a function of capillary pressure from 5 to 95°C. To overcome problems encountered at high temperature, a modified Tempe pressure cell containing a soil sample is suspended in a constant‐temperature water bath. The cell's porous plate is in direct contact with circulating bath water, thus eliminating the problem of entrapped air bubbles. A balance located above the water bath measures water content changes in the soil by weighing the entire pressure cell under water. The technique is designed to measure soil water retention characteristics and to make transient outflow estimates of the soil water diffusivity at temperatures from 5 to 95°C. We also used the technique to determine the isobaric temperature dependence of water retention in soil. Results indicate that at constant capillary pressure, the relationship between moisture content and temperature is hysteretic.
Potassium‐Calcium Exchange in a Multireactive Soil System: I. Kinetics
Authors: Jardine P. M. , Sparks D. L. 
Published: July 2010

AbstractThe kinetics of K exchange were investigated in Ca‐saturated samples from the Ap horizon of an Evesboro soil from Delaware. Biphasic kinetics characterized the first‐order plots for K adsorption and desorption at 283 and 298K with the two simultaneous reactions being attributed to exchange sites with varying reactivity for K and Ca ions. The rapid reaction was ascribed to exchange sites of the soil that are readily accessible to cation exchange reactions, whereas the slow reaction was attributed to exchange sites that are difficultly accessible to cation exchange reactions. Confirmation of the hiphasic kinetics was achieved through the use of cetyltrimethylammonium bromide (CTAB). Parabolic diffusion plots for K adsorption and desorption at 283 and 298 K indicated that an intraparticle diffusion process may be rate limiting for the difficultly accessible sites of the soil. The initial deviation from linearity of the parabolic plots for K desorption suggested that film diffusion may be rate limiting for desorption on readily accessible sites of the soil that form strong bonds with Ca ions. At 313 K the initial rapid kinetics of exchange was no longer present, and the exchange process was described by a single first‐order reaction. The parabolic plots at 313 K suggested that this phenomenon could possibly be attributed to the finite rate at which the polymer structure of soil organic matter changes in response to the adsorption and desorption of the two reacting cations.
Effect of pH on Saturated Hydraulic Conductivity and Soil Dispersion
Authors: Suarez D. L. , Rhoades J. D. , Lavado R. , Grieve C. M. 
Published: July 2010

AbstractThe adverse effects of exchangeable sodium on soil hydraulic conductivity (K) are well known, but at present only sodicity and total electrolyte concentration are used in evaluating irrigation water suitability. In arid areas, high sodicity is often associated with high dissolved carbonate and thus high pH, but in humid areas high sodicity may be associated with low pH. To evaluate the effect of pH (as an independent variable) on K, solutions with the same SAR and electrolyte level were prepared at pH 6, 7, 8, and 9. Saturated K values were determined at constant flux in columns packed at a bulk density of 1.5 Mg m−3. At pH 9, saturated K values were lower than at pH 6 for a montmorillonitic and a kaolinitic soil. For a vermiculitic soil with lower organic carbon and higher silt content, pH changes did not cause large K differences. Decreases in K were not reversible on application of waters with higher electrolyte levels. The results from the K experiments were generally consistent with optical transmission measurements of dispersion. Although anion adsorption was at or below detection limits and cation exchange capacity (CEC) was only slightly dependent on pH, differences in pH effects on K among soils are likely due to differences in quantities of variable‐charge minerals and organic matter.
Long‐Term Reactions of Copper(II) in a Contaminated Calcareous Soil
Authors: McBride M. B. , Bouldin D. R. 
Published: July 2010

AbstractThe concentrations of total and uncomplexed Cu(II) were measured in water extracts from a soil contaminated at least a half century ago. The total Ca concentration in the topsoil was about 3150 mg/kg of soil. Estimates of uncomplexed (free) Cu based on ion‐selective electrode data indicated that at least 99.5% of the Cu in soil solution was in an organically complexed form. This percentage was decreased by adjusting the soil pH downward. The concentration of uncomplexed Cu in soil solution increased with decreasing pH, but the total soluble Cu was relatively insensitive to pH change. Extraction of the soils with DTPA, pyrophosphate, and other selected reagents, as well as analysis of these extracts by electron spin resonance, revealed that the form of Cu2+ adsorbed in the soil was probably largely inorganic. Although solubility data indicated that the soil solution was undersaturated with respect to Cu hydroxide and hydroxy‐carbonate precipitation, malachite had crystallized on limestone surfaces.
Wheat Response to Sodium Uptake under Zonal Saline‐Sodic Conditions
Authors: Devitt D. , Jarrell W. M. , Jury W. A. , Lunt O. R. , Stolzy L. H. 
Published: July 2010

AbstractPlants growing in saline‐sodic soils are usually subjected to the zonal distribution of salts. The ability of a root system to tolerate high levels of soluble salts and in particular high levels of Na+ is partially due to the compensatory uptake of water and ions in the more favorable regions, thus leading to an improved water and nutrient status of the plant. The objective of this investigation was to determine the uptake of Na+ under zonal saline‐sodic conditions and to determine what impact Na+ accumulation had on the overall water, nutrient and growth status of the plants. The experiment was conducted in lysimeters packed with four soil types, with wheat as the test crop. Electrical generating plant blowdown water (EC 6.9 dS/m) was used as the irrigation source on the treated lysimeters. A 10% leaching fraction was imposed on all lysimeters. Sodium‐22 was applied to each of the salinized lysimeters at different times to establish different 22Na positions with depth. Plant and soil samples and soil solution extracts were taken during the experiment and analyzed for Na+, K+, Ca2+, Mg2+, Cl‐, and 22Na. Electrical conductivity was also measured on soil and extracted soil water samples. Fresh to dry weight ratios of the plant and yield estimates were also obtained. An excellent correlation was found between the depth weighted ECSE/θ and the cumulative evapotranspiration. Incorporating the fractional water uptake (WJ) with the ECSE/θ values with depth improved the correlation between ECSE/θ and the cumulative evapotranspiration. Plants that had higher dry matter production and evapotranspiration rates also had higher Na+ accumulation. This we believe was manifested by a positive response to more favorable ECSE/θ regions where Na+ was effectively used in osmoregulation. Sodium‐22 results indicated that the regions closest to the surface were the most active in terms of Na+ uptake. Finally, as the evapotranspiration rate decreased so did the yield and this was directly linked to soil type. Yield estimates as high as 7.5 Mg ha−1 were obtained on the soils with the higher CEC and water holding capacities.
Sulfur Nutrition of Rapeseed II. Effect of Time of Sulfur Application
Authors: Janzen H. H. , Bettany J. R. 
Published: July 2010

AbstractA growth chamber pot experiment was conducted to compare the efficiency of 35S labeled sulfate applied at various stages of growth (at seeding, rosette, bud, and flowering stages) in rapeseed grown on S‐deficient soils. Plant uptake of fertilizer S was generally higher when S was applied at later growth stages. Much of the S applied during these stages, however, accumulated in excessive amounts within the leaves and was not retranslocated despite severe S shortages during seed formation. Seed yields were not affected by time of S application except under conditions of severe S stress where S applied after the rosette stage did not allow recovery of maximum seed yields. Plant maturity was delayed when S was applied after the rosette stage. The results suggest that S deficiency diagnosis using plant tissue analysis will allow successful amendment of S deficiency in rapeseed providing sulfate is applied during or shortly after the rosette stage.
Identification of Pedogenic Carbonates using Stable Carbon Isotope and Microfabric Analyses
Authors: Rabenhorst M. C. , Wilding L. P. , West L. T. 
Published: July 2010

AbstractIn soils formed from limestone, it is often difficult to distinguish between inherited and pedogenic carbonate. In nature, both thermodynamic and kinetic factors have caused fractionation of C isotopes. While marine carbonates usually have δ13C values near zero, the processes of pedogenic carbonate formation result in considerably lower values, which are dependent only on the δ13C of the soil CO2 gas. Therefore, a simple proportionality may be employed to quantitatively estimate pedogenic carbonates in the soil.Seven pedons formed over Cretaceous limestone in Central and West Texas were studied. The δ13C values were determined for the parent carbonates, soil organic matter, and for the various carbonate‐enriched horizons. Both finely disseminated carbonates in A horizons and massive indurated petrocalcic materials were confirmed by isotopic analyses to be primarily of pedogenic origin. Characteristic microfabrics were correlated with isotopic assay of massive petrocalcic materials which may be diagnostic for identification. Although generally useful, isotopic analysis underestimates the pedogenic component in certain carbonate forms, including laminar caps and some concretions and pendants. It is postulated that a different mode or environment of formation for these forms is responsible for discrepancies with theoretical values.
A Unifying Quantitative Analysis of Soil Texture
Authors: Shirazi Mostafa A. , Boersma Larry 
Published: July 2010

AbstractThe soil texture triangle used by the U.S. Department of Agriculture is converted into a new texture diagram which contains all information in the original triangle, but additionally, gives mean particle size and particle size standard deviation of soil samples. Thus, mechanical analysis information on percents of clay, silt, and sand together with particle‐size limits for clay, silt, and sand are found in a single unified system. The new diagram provides greater resolution in detecting classified soil samples within a texture region, it can be extended to cover coarse fragments, and other soil texture classifications can be incorporated into it.