bluuebunny/crossref_metadata_2025_split huggingface dataset:
Adsorption and Availability of Phosphorous Following the Application of Limestone to an Acid, Aluminous Soil
Authors: Sims J.T. , Ellis B. G. 
Published: July 2010

AbstractChanges in the adsorption and availability of P in an acid, aluminous soil (surface and subsoil) were evaluated following liming to neutralize 1N KCl‐exchangeable Al (minimal liming) or to pH 6.8 as determined by the SMP (Shoemaker‐McLean‐Pratt) buffer method. Langmuir adsorption isotherms were utilized to ascertain changes in P adsorption. A greenhouse bioassay was conducted to evaluate differences in P availability to plants (Oats, Avena sativa L. cv. Korwood) due to liming and incubation treatments. Results from these studies confirm that minimal liming is the most effective approach, from both agronomic and economic standpoints. Minimal liming optimized P uptake and minimized the P adsorption maxima (Langmuir b values). Liming by the SMP recommendation did not improve P uptake despite the application of three times as much lime, and also markedly reduced exchangeable Mg. Aging of adsorbate surfaces in the soil reduced their bonding intensity for P (Langmuir K), as did increasing soil pH. Development of ordered, less soluble Al‐OH polymers with fewer nonstructural OH groups capable of ligand exchange with P is postulated as the mechanism underlying these observations. Increases in pH‐dependent negative surface charge and P adsorption by free CaCO3 may be involved.
An 8‐Hydroxyquinoline Method for Labile and Total Aluminum in Soil Extracts
Authors: James Bruce R. , Clark Christopher J. , Riha Susan J. 
Published: July 2010

AbstractThe 8‐hydroxyquinoline method was modified to measure kinetically labile Al in aqueous soil extracts containing Al‐complexing ligands and to measure total soluble Al after removal of fluoride and organic C. Nonlabile Al complexed by F, C, Si, and OH in the original samples is calculated as the difference between total and labile forms. The method measures as little as 100 ng of Al in soil extracts and natural water samples.
Potassium Rates and Sources for Coastal Bermudagrass
Authors: Nelson L. R. , Keisling T. C. , Rouquette F. M. 
Published: July 2010

AbstractDuring the past few years stands of ‘Coastal’ Bermudagrass (Cynodon dactylon L. Pers) have been reduced even though recommended rates of fertilizer have been applied. Many of the soils tested have been low in potassium. The objectives of this study were to determine (i) if the recommended fertilization rates of K were sufficient for optimum yield, (ii) the effect of single and split applications of K on forage yield, and (iii) the advantages of sulfur‐coated KCl or K2SO4 on forage yield production of Coastal Bermudagrass. Coastal bermudagrass was fertilized with nine potassium treatments on Cuthbert fine sandy loam (Typic Hapludult; clayey, mixed, thermic) and Darco fine sand (Grossarenic Paleudult; loamy, siliceous, thermic) soils for 3 years at Overton, Tex. Potassium treatments included rates of 0, 139, and 278 kg K/ha as KCl in single and split (four) applications. In addition, sulfur‐coated muriate of potash (S‐KCl) and sulfur‐coated potassium sulfate (S‐K2SO4) were applied at both 139 and 278 kg K/ha. On the Cuthbert soil a slight forage yield increase due to the K treatments was measured in the 1st year. Highly significant forage yield responses were noted on this soil in both the 2nd and 3rd years. On the Darco soil, small but insignificant increases in forage yield were measured in the 1st and 2nd years. Forage yield was not significantly higher at 278 than at the 0 kg K rate until the 3rd year. Forage yield responses tended to occur late in the growing season usually at harvest three or four, indicating a depletion of available K reserves. Improved yields were not observed for split applications of K. Sulfur‐coated KCl tended to produce highest forage yields annually and at several of the harvest dates. The S‐coated treatments generally resulted in lowest soil pH values. Available K was reduced significantly in the surface 15 cm after 3 years on both the 0 and 139 kg K/ha rates. The 278 kg K/ha treatment resulted in exchangeable‐K levels of 146 and 104 kg K/ha at the 0‐ to 15‐cm depth for the Cuthbert and Darco soils, respectively, at the termination of the study. These K levels were below the original soil K levels for both soils. Results indicate that in the long term, soil K would be depleted by high yields of Coastal bermudagrass with the K rates used in this study.
On the Measurement of Permanent Charge in Oxisols
Authors: Sposito Garrison 
Published: July 2010

AbstractIt is shown that the method used recently by Tessens and Zauyah to measure net permanent charge in Oxisols, based on a recommendation by Gillman and Uehara, can be justified theoretically without an appeal to diffuse double‐layer theory, or to any other detailed, molecular model of the interfacial region. The mathematical relationship between permanent charge and the net adsorbed ion charge at the point of zero salt effect, which forms the basis of the Gillman‐Uehara method, can be derived solely from the law of surface charge balance under the assumption that the point of zero salt effect is equal to the point of zero net proton charge.
Tracing Subsurface Flow on Roadcuts on Steep, Forested Slopes
Authors: Megahan Walter F. , Clayton James L. 
Published: July 2010

AbstractIn situ hydraulic conductivity was determined in a forested soil in the Idaho batholith by a tracer technique, and values were compared to hydraulic conductivity determined in the laboratory on cored samples. We injected NaCl solutions into piezometers placed in soil above a roadcut, and determined time for Na+ or Cl‐ to appear in outflow at the roadcut during saturated subsurface flow generated from spring snowmelt. Hydraulic conductivity values determined with the NaCl tracer averaged an order of magnitude greater than laboratory derived values. This is likely due to rapid flow in macropores formed from root channels or other biological activity that cannot be sampled by conventional coring and laboratory conductivity tests. Although the field tests indicated flow was clearly non homogeneous and anisotropic, an evaluation of the Reynold's number for the test conditions indicated Darcy flow was occurring. Sodium analysis provided a more distinct peak than Cl‐ when both concentrations were plotted vs. time.
Multifactor Kinetics of Phosphate Reactions with Minerals in Acidic Soils: I. Modeling and Simulation
Authors: Lin Chenfang , Busscher W. J. , Douglas L. A. 
Published: July 2010

AbstractA mathematical model was developed to simulate phosphate reactions with minerals in acidic soils. Phosphate in solution was assumed to react with kaolinite, gibbsite, and goethite simultaneously. Each reaction had a two‐step sorption mechanism, i.e., mineral + solution P ⇄ labile P ⇄ nonlabile P, where labile and nonlabile forms are defined as isotopically exchangeable and nonexchangeable, respectively. The first step of the sorption mechanism followed the kinetic version of the Langmuir adsorption isotherm and was a second‐order reaction in nature. The second step of the sorption mechanism was a linear reversible kinetic equation. Seven ordinary differential equations describing the system were solved by numerical methods. The model effectively simulated the trend of phosphate reactions with soil minerals. Using the model to study the adsorption isotherm, we found that the Langmuir plot, i.e., concentration/adsorption vs. concentration, was linear when minerals had relatively homogeneous adsorption rates (or adsorption energies) and was nonlinear for widely differing rates, implying that a homogeneous surface provides a sufficient condition but not a necessary condition for a linear Langmuir plot. Simulation and analysis of a two‐surface Langmuir equation supported this finding.
Determination of Total Sulfur and Chlorine in Plant Materials by Ion Chromatography
Authors: Busman L. M. , Dick R. P. , Tabatabai M. A. 
Published: July 2010

AbstractA simple and precise ion chromatographic (IC) method for simultaneous determination of total S and Cl in plant materials has been developed. It involves combustion of a plant sample (20–100 mg) in a Schoniger‐type oxygen flask containing 25 mL of deionized water. The SO2‐4 and Cl‐ formed in the aqueous solution (the S and Cl gases produced are absorbed by water) are determined by using a Dionex Model 10 IC. The IC method is based on separation of the anions by a separator column containing Dionex low‐capacity anion exchange resin in the HCO‐3 form and on converting the various anions to their corresponding acids by a suppressor column containing a strong acid cation exchange resin in the H+ form. A solution 3.0 mM NaHCO3 + 1.8 mM Na2CO3 is used as the eluent, and electrical conductivity is used as the mode of detection. Results obtained for total S in a variety of plant materials by the IC method agreed closely with those obtained by the methylene blue method after digestion with NaOBr. The average total S values of 15 plant samples by the two methods were 0.255 and 0.259%, respectively. Comparison of the results obtained for Cl by the IC method and by a colorimetric method involving the use of mercuric thiocyanate and ferric ammonium sulfate showed that the averge Cl values for the plant samples were 0.380 and 0.377%, respectively. The recovery of total N and P was not quantitative. A single operator can perform about 40 analyses in a normal working day.
Nitrogen Fertilization Practices for Sequential Cropping of Wheat, Turnips, and Sweet Corn
Authors: Sanmaneechai M. , Koehler F. E. , Roberts S. 
Published: July 2010

AbstractThe fertilizer requirement for multiple or sequential cropping needs to be better defined. Therefore, a three‐crop field experiment was conducted on a Warden silt loam (coarse‐silty, mixed mesic, Xerollic Camborthids) to study the effects of preplant soil mineral N and rates of applied N on yield and N uptake by spring wheat (Triticum aestivum L.), turnips (Brassica rapa L.), and sweet corn (Zea mays L.). Spring wheat and turnips were grown sequentially in 1979 followed by sweet corn in 1980. Wheat yield was not significantly increased with over 135 kg N/ha, but near maximum yield of 7.5 Mg/ha on the yield curve was at 180 kg N/ha. The concentration of N in the straw and grain continued to increase with N rates of 180 and 270 kg/ha. Yield of turnips (roots plus tops) which reached 5.8 Mg/ha and N uptake increased with increasing N rates up to the maximum use of 270 kg/ha. Only the highest rate of N applied for wheat significantly increased yield and N uptake of the following turnip crop. Sweet corn yields increased to 23 Mg/ha with increasing N rates up to 135 kg/ha, and then leveled off, whereas N uptake increased up to 180 kg N/ha. Residual effects from N applied for previous crops increased yield and N uptake of sweet corn. Responses by corn to residual N were greatest where N was applied for both wheat and turnips and least where N was applied for spring wheat only. It was concluded that turnips benefited less than sweet corn from residual and mineralizable N. The total N uptake by three crops exceeded the amount of N applied showing that N mineralization during crop growth was an important factor in the N uptake by the crops.
Importance of Phosphate Buffer Power for Phosphate Uptake by Rye
Authors: Prabhakaran Nair K. P. , Mengel K. 
Published: July 2010

AbstractAs soil test data for available P are often unsatisfactory, it was investigated whether the integration of the P buffer power of soils would improve the information from soil tests. The P buffer power of eight soils differing widely in their characteristics was assessed by plotting the calcium‐lactate exchangeable P (P quantity) vs. the electro‐ultrafiltration extractable P (P intensity). After dressing these soils with increasing amounts of soluble phosphate, they were analyzed for available P after an incubation period of 1 week by extracting P using electro‐ultrafiltration (EUF‐P) and calcium‐lactate (CAL‐P). The P concentration in the tops and the P uptake of young rye (Secale cereale L.) plants grown on these soils in pots supplied with five increasing P rates were correlated with the EUF‐P and CAL‐P soil test data. Significant and highly significant correlations between soil test and the P uptake and soil test and P concentration in rye seedlings, respectively, were obtained. These correlations were further much improved when the P buffer power of soils was integrated into the computation in the form of a multiple regression analysis. The R2 thus obtained was about 0.8, showing that about 80% of the variance in P uptake and P concentration in plant tops can be related to the variance in the P soil test data (CAL or EUF technique) and to the variance of the P buffer power of soils. It is concluded that soil tests for available soil P can be substantially improved by taking into consideration the P buffer power of soils.
Rapid Method to Obtain Carbonate‐free Residues from Limestone and Petrocalcic Materials
Authors: Rabenhorst M. C. , Wilding L. P. 
Published: July 2010

AbstractA relatively rapid procedure for carbonate removal was desired for the study of noncarbonate residues from indurated calcareous materials. Carbonates were therefore removed from two calcareous smectite containing samples using various acid treatments. The degree of clay mineral alteration was assessed by x‐ray diffraction (XRD) and cation exchange capacity (CEC) of residue clay (< 2‐µm) fractions. Minor reductions in CEC were observed as a consequence of carbonate removal using pH 5.0 sodium acetate (NaOAc) buffer. Mineralogical changes were not detected by XRD. Further lowering of the NaOAc buffer pH to 2.5 had little or no additional effect. Use of pH 4.5 NaOAc buffer for dissolution of gravel size (< 8‐mm) limestone and petrocalcic materials greatly reduced the time necessary for carbonate removal compared with traditional pH 5.0 NaOAc procedures.
The Release of Nonexchangeable Ammonium (15N Labelled) in Wetland Rice Soils
Authors: Keerthisinghe G. , Mengel K. , De Datta S.K. 
Published: July 2010

AbstractThe release of nonexchangeable (fixed) NH+4 was studied for three representative rice soils of the Philippines. Soil samples from these soils were treated with 15NH+4 in the laboratory so that they contained appreciable amounts of nonexchangeable NH+4 in 15N form. Special soil holders were filled with the labelled soil and incubated in the wetland rice soils from July to October at a depth of 0.2 m. During this period of incubation, highly significant amounts of labelled nonexchangeable NH+4 were released from all three soils. For the Maligaya silty clay loam and Guadalupe clay, both containing vermiculite, the total release of nonexchangeable NH+4 was higher than the release of labelled nonexchangeable NH+4 showing that non‐labelled NH+4 was released as well. 15N analysis of the rice plants showed that the nonexchangeable labelled NH+4 was subsequently available to the crop. Assuming a soil bulk density of 1 and a rooting depth of 0.2 m release of nonexchangeable NH+4 from the Maligaya silty clay loam ranged from 80 to 100 kg N ha−1, while for the Guadalupe clay and Santa Rita clay the net release of nonexchangeable NH+4 amounted to about 20 to 40 kg N ha−1, respectively. It is concluded that nonexchangeable NH+4 may play a major role in N nutrition of rice crops grown in wetland rice soils rich in vermiculite.
Reduction of Natural Ferric Iron Chelators in Disturbed Forest Soils
Authors: Perry D. A. , Rose S. L. , Pilz D. , Schoenberger M. M. 
Published: July 2010

AbstractHydroxymate siderophores (HS) are high affinity FE3+ chelators which are produced and secreted into the soil by various soil microflora, including mycorrhizal fungi. HS are important in the iron nutrition of both the microorganisms which produce them and higher plants, and they may also protect higher plants from soil‐borne pathogens. We used a standard bioassay technique to compare HS concentrations in soils from 10 pairs of logged and adjacent unlogged sites in various areas of Oregon. In 8 of the 10 sites HS concentrations were significantly lower in soils from logged areas than in those from adjacent undisturbed forests. HS reductions were greater where slash was burned than where it was unburned or windrowed. Pot tests of soils from one site indicated that Douglas‐fir seedlings (Pseudotsuga menziesii [Mirb.] Franco) were iron limited in logged and burned but not in undisturbed forest soils. Soil pasteurization induced iron limitation in undisturbed soils, which suggests that iron limitation in soils from the logged and burned area may have been due to reduction of HS‐producing organisms.
Soil Manganese: E Values, Distribution of Manganese‐54 among Soil Fractions, and Effects of Drying
Authors: Goldberg S. P. , Smith K. A. 
Published: July 2010

AbstractThe Mn labile pool was determined in a wide range of United Kingdom soils, using 54Mn tracer and two different extractants, CaCl2 and DTPA. Good agreement was obtained between E values obtained by two different equilibration procedures in CaCl2, but for most soils the concentrations of CaCl2‐extractable Mn were considerably lower than the E‐values. Higher E‐values were obtained in DTPA than in CaCl2, indicating that the former dissolved some nonisotopically exchangeable Mn. The rate of disappearance of 54Mn from the soil solution, and its distribution in various fractions, differed greatly between the soils. Generally, the radioisotope labeled all the soil fractions determined, with the majority of 54Mn associated with the water‐soluble + exchangeable, organically bound and easily reducible oxide fractions. When the labeled soils were subjected to air and oven‐drying, net gains of 54Mn were observed in the water‐soluble + exchangeable, resistant and residual Mn fractions, with corresponding reductions in the easily reducible oxide fractions. Upon drying, native Mn increased in the water‐soluble + exchangeable and EDTA‐extractable fractions. Possible mechanisms for these changes are discussed.
Estimation of Water Potential Components of Saline Soils of Great Basin Rangelands
Authors: Roundy Bruce A. 
Published: July 2010

AbstractA rapid method is described to assess the solute and matric components of the total soil water potential at field water contents of a saline soil in central Nevada. The solute potential is estimated from saturated paste conductivity (ECp) measurements easily made on the conductivity cell of an instant salinity meter and assumes that the salt concentration varies inversely with water content. The method requires determination of the relationship between ECp and the electrical conductivity of the saturated paste extract, ECe. The total water potential is measured with a Peltier psychrometer. Subtraction of the solute potential from the total water potential results in an estimate of matric potential. Matric potentials estimated in this way were similar to those determined by a pressure plate at volumetric water contents greater than 0.09 m3 m−3 soil and soil ECe's < 15 dSm−1. The method tends to underestimate solute potentials and overestimate matric potentials of soil with lower soil water contents and higher salinity. These measurements are useful in determining plant adaptability on saline, semiarid rangeland soils.
Leaching Losses and Plant Recovery from Various Sulfur Fertilizers
Authors: Korentajer Leonid , Byrnes Bernard H. , Hellums Deborah T. 
Published: July 2010

AbstractTwo greenhouse experiments were conducted with soils fertilized with various S fertilizers. The soils were subjected to percolation during early growth of a corn (Zea mays, L. var. Funks G5757) crop to determine the effects of leaching rate, sulfur rate, and S source on SO2‐4 leaching losses and plant growth. In the first experiment, the effects of percolation rate (0–6.1 mm d−1) and rate of gypsum application (0–40 µg S g−1) on SO2‐4 leaching losses and S recovery by two successive crops were studied. Increasing the percolation rate greatly increased SO2‐4 leaching losses and decreased the apparent fertilizer recovery by the first crop. Apparent S recovery was also greatly reduced with increasing amounts of applied gypsum. In the second experiment, S leaching losses from gypsum and anhydrite of various particle sizes and from powdered elemental S were evaluated at one percolation rate (3.9 mm d−1). The rate of SO2‐4 leaching loss from powdered gypsum and anhydrite gradually decreased with time, indicating a decrease in the dissolution rate of the source as the amount of solid phase material decreased. Increasing the particle size of the materials decreased the leaching losses but had no effect on apparent S recovery by the plants. At a given particle size other than powdered materials, there were no differences in leaching losses between gypsum and anhydrite. The amount of powdered gypsum leached, however, was three times greater than the amount of powdered anhydrite leached. Leaching losses from powdered elemental S were similar to the losses from the larger‐sized particles of gypsum and anhydrite. Moderate to high percolation rates led to SO2‐4 losses and decreased fertilizer efficiency. Increasing the size of gypsum particles and the use of anhydrite are promising methods of reducing such losses.
Relating Rainfall Erosivity Factors to Soil Loss in Kenya
Authors: Ulsaker L. G. , Onstad C. A. 
Published: July 2010

AbstractRunoff plots were established on a representative soil site in Kenya in 1980 to evaluate soil and water losses as influenced by climate, soil, and management practices. Fifteen erosivity factors were regressed to ascertain best fit on the soil loss from 3 fallowed plots for each of 35 storms between March 1982 and April 1983. Two of the best rainfall erosivity factors with their respective coefficients of determination are: total kinetic energy times maximum 30‐min intensity (EI30), r2 = 0.69, and rainfall amount times the maximum 30‐min intensity (AI30), r2 = 0.72. A regression equation was developed relating EI30 to rainfall amount, A. The coefficient of determination was 0.902. Soil erodibility for this Alfisol was found to be 0.0314 tonne hectare hour per hectare megajoule millimeter or 0.24 in customary English units. Erodibility factor values ranged from 0.07 for storms producing soil losses less than 1 t/ha to 0.55 for storms producing soil losses greater than 10 t/ha.
Scale Factors in Soil Science
Authors: Tillotson Patricia M. , Nielsen Donald R. 
Published: July 2010

AbstractMethods used in soil science to derive scale factors for soil properties include the dimensional method called similitude analysis which is based on physical characteristics of a soil system and an empirical method called functional normalization which is based on regression analysis. In the past, researchers have assigned physical significance to empirically determined scale factors on the basis of corresponding scale factors derived from similitude analysis. This paper demonstrates that scale factors determined through functional normalization are not always physically equivalent to those determined from similitude analysis. This paper also describes two additional dimensional methods that can be used to derive scale factors for soil properties, namely dimensional and inspectional analysis. Examples of dimensional analysis, inspectional analysis, and functional normalization are presented for a variety of soil science disciplines.
Absorption of Gaseous Ammonia by Douglas‐Fir
Authors: Pang Patrick C.K. 
Published: July 2010

AbstractAbsorption of labelled ammonia (15NH3) by excised shoots of Douglas‐fir [Pseudotsuga menziesii (Mirb.) Franco] was determined under laboratory conditions to increase as the ammonia concentration increased from 0 to 1.09 volume %. Photosynthesis was unaffected by the presence of ammonia except at the highest concentration studied. Although Douglas‐fir is demonstrated to have the potential to absorb ammonia, the amount of ammonia absorbed under field conditions is suggested to be influenced by factors affecting rates of diffusion and mass flow of NH3 out of the canopy.