bluuebunny/crossref_metadata_2025_split huggingface dataset:
Origin of the Effects of Citrate, Tartrate, and Acetate on Phosphate Sorption by Soils and Synthetic Gels
Authors: Earl K. D. , Syers J. K. , McLaughlin J. R. 
Published: July 2010

AbstractThe ability of two contrasting soils and synthetic Fe and Al gels to sorb inorganic phosphate (P) in the presence of three commonly‐occurring organic anions was evaluated using sorption isotherms. At 10−3M, citrate was markedly effective in reducing P sorption (50% reduction), tartrate was only moderately effective (20% reduction), whereas acetate had little or no effect (1% reduction) at a final solution P concentration of 0.20 mmole/liter for the four sorbents. A close linear relationship was established between the reduction in P sorption and the amounts of (Fe + Al), Fe, or Al removed from the Fe‐rich soil, Fe gel, or Al gel, respectively, by varying concentrations of citrate and tartrate. At 10−1 M, citrate and tartrate removed 91% of the Fe and 88% of the Al from the Fe and Al gel, respectively, reducing P sorption by 89 and 88%. At equivalent anion concentrations, however, tartrate was sorbed to a greater extent than citrate, resulting in a larger reduction in P sorption by this anion for a given amount of (Fe + Al) or Fe removed from the two soils and Fe gel. The curvilinear relationship obtained between the reduction in P sorption and the amount of (Fe + Al) removed from an Al‐rich soil resulted from the removal, at low organic anion concentrations, of a readily‐extractable form of Al which had little effect on P sorption. A similar finding was obtained for Al gel. The reduction in P sorption observed in the presence of citrate resulted primarily from the elimination of a significant proportion of P‐sorbing sites rather than from the competitive specific sorption of citrate. In contrast, tartrate reduced P sorption through a combined dissolution‐competitive sorption effect. Although 10−1M acetate had little effect on P sorption, a high proportion was sorbed by the sorbents, indicating that the sorption mechanism or site of binding of acetate differs from that of P.
Metal Ion Binding and Exchange with Hydrogen Ions in Acid‐Washed Peat
Authors: Bloom P. R. , McBride M. B. 
Published: July 2010

AbstractTitration and electron spin resonance (ESR) studies of metal ion adsorption processes on acid peat were used to investigate metal‐proton exchange. Localization of ions at carboxylate sites is suggested but the data indicate that chelation mechanisms or sites of greatly different acid strength need not be involved. The peat is observed to behave very much like synthetic cross‐linked polycarboxylic acids in terms of metal ion adsorption. Most of the divalent ions adsorbed at acid pH appear to maintain a hydration sphere while the strongly immobilized Cu2+ ion coordinates directly with functional oxygens of the peat.
Growth and Nutrient Relations of a Grass‐Legume Mixture on Sodic Coal‐Mine Spoil as Affected by Some Amendments
Authors: Safaya N. M. , Wali M. K. 
Published: July 2010

AbstractLaboratory and growth chamber investigations were conducted to study the effects of fertilizers, gypsum, H2SO4, and leonardite (oxidized lignite) on the growth and nutrient relations of a mixed crop of thickspike wheatgrass [Agropyron dasystachyum (Hook.) Scribn.] and yellow sweetclover [Melilotus officinalis (L.) Lam.] on a calcareous sodic coal‐mine spoil. Application of NPK increased the dry matter yield of the two species by 10 and 37 times, respectively. However, sweetclover required P only but wheatgrass yields almost doubled when N was included with P. Inclusion of Zn with NPK decreased the growth of sweetclover, and reduced Mn uptake in both species. Zinc, Mn, Cu, and Fe concentrations in the plants decreased variously with fertilizer applications. P‐fertilization decreased the concentration of K in wheatgrass but not in sweetclover.The two species exhibited differential growth response to leonardite, which was correlated with K+/Na+ ratios in the plants and their Ca‐uptake efficiency. Leonardite increased Na concentration in wheatgrass (Ca‐inefficient) and decreased its growth, but caused a reverse effect on sweetclover (Ca‐efficient). It also decreased K and Zn in wheatgrass, and Cu and Fe in sweetclover. Gypsum tended to alleviate the effects of leonardite on wheatgrass, and increased Zn and Mn content in NPK‐supplied plants. The extractability of applied P was higher from leonardite treated spoil. Sulfuric acid proved more effective than gypsum in releasing Na from the exchange sites in the spoil. Moreover, H2SO4 improved the P status of plants, and increased the yield of wheatgrass to the same extent as did the application of 75 µg P/g spoil from H3PO4 source.
Estimation of Amorphous Material, 1:1 Type Layer Silicates, and Gibbsite Dissolved in Hot Alkali Treatment of Soil Clay
Authors: Calvert C. S. , Weed S. B. , Buol S. W. 
Published: July 2010

AbstractDifferential thermal analysis (DTA) is combined with selective dissolution (hot 0.5N alkali solution) to provide a quantitative estimate of amorphous inorganic material in deferrated soil clays consisting predominantly of 1:1 type layer silicate minerals, gibbsite, and amorphous material. Data from DTA are used to estimate gibbsite and 1:1 type layer silicate minerals in the original and alkali‐treated clay. Correction is then made to the weight loss due to alkali treatment to estimate amorphous inorganic material solubilized in boiling 0.5N NaOH or KOH. Qualitative support for conclusions reached is provided by x‐ray diffraction and infrared spectroscopic studies of the original and treated samples.
High Gradient Magnetic Separation of Iron Oxides and other Magnetic Minerals from Soil Clays
Authors: Schulze D. G. , Dixon J. B. 
Published: July 2010

AbstractA filter of ferromagnetic stainless steel wool, placed in a strong magnetic field, provides the magnetic field gradients necessary to trap weakly magnetic clay size particles from a flowing suspension.Of the total dithionite‐citrate‐bicarbonate extractable Fe2O3 in the 2–0.2 µm size fraction of six soils, 70 to 94% was recovered in the magnetic fraction which consisted of 1.6 to 27.7% free Fe2O3 by weight. For the <0.2 µm size fraction, 11 to 40% of the total free Fe2O3 in the size fraction was recovered in the magnetic fraction which contained 2.8 to 53.1% free Fe2O3 by weight. Larger particles are captured more efficiently because of their greater overall magnetic attraction. Goethite, hematite, lepidocrocite, and anatase are concentrated in the magnetic fraction, while quartz is concentrated in the tailings. Chlorite is effectively concentrated in the magnetic fraction. Although mica, vermiculite, and smectite are often found in both the tailings and the magnetic fraction, vermiculite and mica appear to be more concentrated in the magnetic fraction. The concentration effect on kaolinite appears to be dependent on the particle size and rate of flow through the magnetic filter.
Flux‐Controlled Sorptivity Measurements to Determine Soil Hydraulic Property Functions
Authors: Dirksen C. 
Published: July 2010

AbstractUsing a new method, the hydraulic diffusivity and conductivity functions D[θ] and K[h] can be determined over most of their range in about 4 hours. This method uses a series of fast and simple, one‐dimensional adsorption measurements for which the cumulative volumes of absorption are controlled proportional to the square root of time with syringes driven by cames. Each combination of motor speed, can size, and syringe size represents an imposed sorptivity for which the water content and/or pressure head at the interface must be measured after they become steady. Steady values are normally reached after only a few minutes. Pressure heads can be recorded during the absorption runs, and at the end a soil sample for gravimetric water content determination can be obtained in about 15 sec. Hydraulic diffusivity and conductivity functions derived from measured sorptivity functions were obtained for a variety of undisturbed and hand‐packed soil columns. They all showed excellent agreement with independent data. The flux‐controlled boundary resulted in uniform wetting almost every time, whereas previously used potential‐controlled boundary conditions often caused nonuniform wetting, which prevented accurate evaluation of sorptivities. The speed, range, and accuracy of this improved version of the sorptivity method compare favorably with other available methods. The method is suitable for routine and large scale use.
A Numerical Study of the Effects of Noncapillary‐Sized Pores Upon Infiltration
Authors: Edwards W. M. , van der Ploeg R. R. , Ehlers W. 
Published: July 2010

AbstractA numerical solution to the unsaturated soil moisture flow equation was used to model infiltration into a soil containing surface‐connected noncapillary holes. Input parameters used to demonstrate the model were those from an untilled silt loam soil whose infiltration characteristics are strongly influenced by worm holes, especially when rainfall rates are high. The two‐dimensional model allows for vertical infiltration from the soil surface and for lateral infiltration from a vertical hole after excess precipitation on the surface runs into the hole.The model shows that the number of holes per unit soil area, as well as the diameter and depth of the holes, greatly influence infiltration and surface runoff. The assumption of noncapillary flow through continuous holes or cracks may be used to explain some of the observed deviations from capillary flow theory and the fast movement of surface‐applied agricultural chemicals through the soil profile.
Hydrodynamic Dispersion During Infiltration of Water into Soil
Authors: Elrick D. E. , Laryea K. B. , Groenevelt P. H. 
Published: July 2010

AbstractThe analysis of hydrodynamic dispersion during one‐dimensional sorption of water by soil (horizontal flow) is extended to include the gravitational effects present during one‐dimensional infiltration (vertical flow). A power series form for the solution is developed in a manner similar to that developed by Philip for water movement during infiltration. Similar to the sorption analysis, the longitudinal dispersion coefficient was assumed to be a function of water content only. A computer simulation program using CSMP was used to solve the associated differential equations. A single program was found to be suitable as long as the Boltzman parameter (distance divided by the square root of time) was used as the independent variable throughout. An algorithm was developed to give successively better solutions of the soil water diffusion and hydrodynamic dispersion equations.Infiltration experiments were carried out on a clay loam soil. Both the water and chloride content profiles preserved similarity in terms of the Boltzman parameter. Water and solute coefficients of the power series solutions were calculated from horizontal infiltration and hydraulic conductivity data and used to predict both the water and solute profiles during vertical infiltration. Good agreement between the vertical infiltration data and the theoretical predictions was obtained.
Phosphate Uptake by Corn as Affected by Soil Characteristics and Root Morphology
Authors: Schenk M. K. , Barber S. A. 
Published: July 2010

AbstractPhosphate uptake by plants growing in soil is influenced by the P uptake properties of the root and the P supply characteristics of the soil. This system may be described by mathematical simulation models. The objective of this research was to determine if a model used successfully for describing K uptake by corn (Zea mays L.) could be used for describing P uptake. A growth chamber experiment with corn grain on six soils varying widely in physical and chemical characteristics was conducted. Three harvests were made and root morphology and P uptake were measured. The significance of the differences in root morphology and in soil P‐supply parameters of initial P concentration in soil solution, buffer power, and effective diffusion coefficient for P were determined by using them in the Claassen‐Barber simulation model which considers these soil factors, root morphology, and root physiology to predict P uptake by plants. The calculated P uptake, y was correlated (r = 0.93) with observed P uptake, x. The regression equation, y = 1.09x + 27.3 indicated a 9% overprediction of P uptake which was probably because the model did not consider root to root competition for P. The parameters used in this objective simulation model appear to be the important ones determining P absorption by plants from soil. In this study, root morphology varied with soil and was highly correlated with P uptake (r = 0.88). This simulation model should be a useful tool in P fertilization research.
Effect of Concentration on Decomposition of Some 14C‐labeled Phenolic Compounds, Benzoic Acid, Glucose, Cellulose, Wheat Straw, and Chlorella Protein in Soil
Authors: Martin J. P. , Haider K. 
Published: July 2010

AbstractThe decomposition of ring‐14C‐labeled anisic, ferulic, and benzoic acids and of O14CH3‐labeled ferulic acid at concentrations of 1 to 10,000 ppm and of UL cellulose, glucose, wheat straw and Chlorella protein at 1 – 50,000 ppm was followed in Chino loam (pH 5.6) and San Jacinto sandy loam (pH 8.0) over a 12‐week incubation period. A smaller proportion of the ring C of the benzenoid compounds and glucose was evolved as CO2 from the lower additions than from the higher applications. The range for C loss for ferulic acid was 40 to 79% for the acid soil and 22 to 33% for the alkaline soil as the concentration increased from 1 to 10,000 ppm. Comparable losses for glucose were 47 – 83 and 65 – 81%; for anisic acid 55 – 79 and 49 – 72%; for p‐hydroxycinnamic acid 54 – 81 and 21 – 53%; and for benzoic acid 68 – 77 and 50 – 79%. Loss of O14CH3 C of ferulic acid and of wheat straw, cellulose, and protein C was not influenced by concentration. Percentage C loss from ring‐14C ferulic and benzoic acids added to initially sterilized and reinoculated acid soil was about 82% and was not influenced by concentration.
Evidence for Clostridia as Agents of Dissimilatory Reduction of Nitrate to Ammonium in Soils
Authors: Caskey William H. , Tiedje James M. 
Published: July 2010

AbstractReduction of NO3‐ to NH4+ was studied in fresh and air‐dried soils which were amended with 15NO3‐ and glucose, acetate, or water and incubated anaerobically. Soils were either untreated or heat‐shocked at 68°C for 1 hour prior to amendment. Ammonium was produced rapidly after the onset of anaerobiosis, and thereafter was incorporated into organic matter. 15NH4+ plus 15N‐organic matter production was observed in glucose‐amended fresh soil in quantities up to 43% of added 15NO3‐ in untreated samples and 55% in heat‐shocked samples after 5 days incubation. In soils unamended with organic carbon, NO3‐ reduction to NH4+ was minor. Pretreatment of the soils either by air‐drying or heat‐shocking increased to a similar extent the amount of NO3‐ reduced to NH4+. The activity of clostridia during the NO3‐ reduction was indicated by the absence of any effect exerted by heat‐treatment, the production of H2 and CO2, and the presence of higher numbers of anaerobic sporeforming bacteria relative to denitrifying bacteria in the air‐dried soil. Also, the most common isolate capable of reducing NO3‐ to NH4+ was a Clostridium spp. The addition of washed spores of a NO3‐‐reducing Clostridium isolated from the soil increased the formation of 15NH4+‐N plus 15N‐organic N fourfold, an accumulation equivalent to 83% of added 15NO3‐‐N.The reduction of NO3‐ to NH4+ in soils was not inhibited by NH4+ or glutamine, indicating that the mechanism of reduction was dissimilatory. This conclusion is supported by studies with several Clostrdium spp. isolated from the soils. The isolates were capable of reducing NO3‐ to NH4+ and exhibited increased cell yields when NO3‐ was included in the growth medium. These studies suggest that the potential for significant dissimilatory NO3‐ reduction to NH4+ exists in most soils, principally in the sporeforming genera of Clostridium and Bacillus, but that this potential is likely expressed only when soils become anoxic and are rich in C.
Corn Yield as Affected by Lime Rate and Type on a Coastal Plain Soil
Authors: Liebhardt William C. 
Published: July 2010

AbstractGround limestone rates of 0, 2.24, and 8.96 metric tons/ha as calcite, dolomite or a mixture of the two were applied to a Kalmia s1 (Typic Hapludult) in 1970 and 1973. Soil pH was 5.7 at the low rate and 6.4 at the high rate in 1977. Corn (Zea mays L.) yield was significantly lower at pH 6.4 compared to pH 5.7. At pH 6.4 dolomite resulted in lower corn yields than did calcite or a mixture of the two. Yield of corn was negatively related to soil pH and higher soil Mg and positively with plant Mn.Extration of soil samples with the double acid extractant from 5 min to 48 hours showed that there was considerable non‐exchangeable Ca and Mg at the high lime rate (pH 6.4), but little or none at the low rate (pH 5.7). The nonexchangeable Ca and Mg appear to be reaction products from dolomite. The ratio of nonexchangeable Mg/Ca is 4.48 on a meq basis which is unfavorable for plant growth and indicates why continued use of dolomite on sandy Coastal Plain soil with a low CEC results in a yield decrease.
Phosphorus Transformations in Alternately Flooded California Soils: I. Cause of Plant Phosphorus Deficiency in Rice Rotation Crops and Correctional Methods
Authors: Brandon D. M. , Mikkelsen D. S. 
Published: July 2010

AbstractRice (Oryza sativa L.) is widely grown on soils continuously submerged during the annual growing season. Upland crops following rice culture often exhibit chlorosis, extremely slow growth, and low productivity. Phosphorus deficiency induced by drainage following soil submergence was shown to exist in crops following rice. Experiments were conducted to clearly define the problem in terms of crop response to P fertilizer on major California rice soils and to determine the most efficient methods of P fertilization.Three field experiments were conducted on Myers, Willows, and Sacramento soils following variable years of annual rice production. Wheat (Triticum aestivum L.) or barley (Hordeum vulgare L.) were fertilized with P rates of 0, 29, 59, and 89 kg/ha applied as band‐placed TSP, broadcast TSP and band‐placed MAP. Phosphorus sources, rates, and method of application were evaluated by plant responses including seedling dry matter, plant total‐P and 2% HAc extractable PO4‐P, plant total‐N, grain yield, and 1,000‐kernel weight.The differential severity of plant P deficiency between the three soils was Myers ⩾ Willows > Sacramento series. Severe plant P‐deficiency was observed in the Myers soil even though the soil NaHCO3‐extractable P level was 16.8 ppm. Soil submergence and drainage‐induced soil P transformations decreased soil P availability to wheat and barley following flooded rice.The relative efficiency of P fertilizer sources and methods was band‐placed MAP > band‐placed TSP > broadcast‐incorporated TSP. Phosphorus band‐placed 3 cm directly below the seed was more efficient than broadcast‐incorporated P in wheat and barley after rice. Band‐placed P resulted in greater P uptake by plants probably because of less soil sorption of fertilizer P and greater P availability relative to broadcast‐incorporated P.
Holocene Soils in Eolian Sediments of Bailey County, Texas
Authors: Gile Leland H. 
Published: July 2010

AbstractThree Holocene geomorphic surfaces and their associated soils and sediments are recognized in sandhills of Bailey County, Texas. Fairview sediments are related to the activities of man since about 100 years B.P. The Muleshoe (100–4,000 years B.P.) and Longview (4,000–7,000 years B.P.) sediments accumulated as a result of erosion initiated by severe droughts in the Holocene.Typic Ustipsamments and Alfic Ustipsamments are the most common Holocene soils in the study area; Psammentic Haplustalfs also occur, but are less common. The Alfic Ustipsamments have two or more continuous clay bands and the Typic Ustipsamments do not. Clay bands occur sporadically in Muleshoe sediments, but continuously in Longview sediments. Argillic horizons and the Psammentic Haplustalfs occur in some of the Longview sediments and in all of the sediments next older than Longview, which may date from latest Pleistocene or earliest Holocene time. Muleshoe sediments 1‐ to 2‐m thick are underlain by buried argillic horizons in many places, and some soils in these areas have been classified elsewhere as Grossarenic Paleustalfs. Thus, some of the soils so classified actually consist in part of buried soils.Clay in the clay bands is thought to have been deposited from clay in suspension on slowing of downward movement of the wetting front. Some clay apparently moves through the upper bands at times of deeply penetrating moisture and then accumulates in bands beneath as the wetting front slows its downward movement. Lateral movement of soil water is also important in the thickening and lateral spread of some bands. Clay accumulation in the bands gradually decreases soil permeability through time, and clay starts to accumulate between bands as well as in them. Since latest Pleistocene or possibly earliest Holocene time, enough clay has accumulated between some of the bands that they are partially obscured.
The Nature and Genesis of Some Salt‐Affected Soils in Iran
Authors: Mahjoory Ramez A. 
Published: July 2010

AbstractSalt‐affected soils are distributed throughout arid to semiarid regions of Iran. They occupy about 15% of the area in the country, an amount equal to the total arable land. These soils are formed in level to depressional landform positions under the influence of a fluctuating ground water table. Three pedons representing different soil series were studied: Amir‐abad (pedon 1), Farsian (pedon 2) and Ahoo‐char (pedon 3). Pedon 1 was classified as a Haploxerollic Natrargid, pedon 2 as an Aquic Natrargid, and pedon 3 as an Aquic Natrargid.The origin of salts is related to the parent materials that formed from saliniferous and gypsiferous marl deposits and carried by water and redeposited.Saturated paste extracts are high in chlorides, sulfates, and carbonates in all three pedons, but increased in amounts from pedon 1 to pedons 2 and 3. ESP and SAR are more than 15 in all three soils studied. The average electrical conductivity (EC) values of pedon 1, 2, and 3 are 13, 16, and 32 mmho/cm, respectively. The pH values vary from 8 – 10.X‐ray diffraction and chemical data indicate that the soils contain vermiculite (18–48%), clay mica (18–28%), interstratified vermiculite and/or chlorite‐clay mica, kaolinite, and quartz. Montmorillonite and attapulgite were found only in pedon 3.