bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of Fertilization and Vesicular‐Arbuscular Mycorrhizal Inoculation on Growth of Hardwood Seedlings
Authors: Schultz Richard C. , Kormanik Paul P. , Bryan William C. 
Published: July 2010

AbstractEight hardwood species were grown in fumigated soil without vesicular‐arbuscular mycorrhizae (VAM) or in soil infested with a mixture of Glomus mosseae and Glomus etunicatus. Three fertilizer treatments of 140, 560, and 1,120 kg/ha of 10‐10‐10 fertilizer were established in combination with the two mycorrhizal treatments. Ten equal applications of NH4NO3, totaling 1,680 kg/ha, were added to all the treatment plots during the growing season. For six of the eight species, the VAM seedlings showed greater height and diameter growth and dry weight production than nonmycorrhizal seedlings. Sugar maple (Acer saccharum Marsh.) and walnut (Juglans nigra L.) displayed no height growth differences. Only boxelder (Acer negundo L.), of the inoculated seedlings, consistently responded to increases in fertilizer level. Nonmycorrhizal seedlings generally showed increased growth with increased fertilizer applications. The growth of the nonmycorrhizal seedlings at the higher fertilizer levels was not sufficient to produce plantable seedlings for artificial regeneration. A difference in host preference for the Glomus spp. symbionts is suggested by the large difference in infection between species. Infection values varied from a high of about 80% for sycamore (Platanus occidentalis L.), green ash (Fraxinus pennsylvanica Marsh.), and boxelder to a low of 40% for sugar maple and sweetgum. The growth data suggest that high quality seedling stock of most of these hardwood tree species can be obtained in nurseries as long as cultural practices in the nursery encourage VAM development.
Sand Grain Micromorphology and Soil Age
Authors: White Kenneth L. 
Published: July 2010

AbstractThe micromorphology of quartz grains (0.5 to 1.0 mm) from three soils developed in granitic alluvium were studied using scanning electron microscopy. The soils are located on riverine terraces in southern California. The soils have been dated as 22,000, 44,000, and 63,000 years before present (YBP). The grains are dominated by solution/precipitation features. The samples from the A horizons are quite similar. Grains from the lower B horizons display an increasing complexity of features with advancing age. The C horizons from the older terrace yield the most diagenetically altered grain surfaces. Age in fact, appears to have greater significance than change in soil texture or water holding capacity.
Infiltration of Fungal and Bacterial Propagules into Soil
Authors: Wilkinson H. T. , Miller R. D. , Millar R. L. 
Published: July 2010

AbstractPhytophthora megasperma zoospores and cysts and Serratia marcescens cells were infiltered during the establishment of a gradient of matric potential in horizontally positioned columns of soil. Tensiometers placed in the soil columns were used to record matric potentials (in situ). In columns wetted a distance of 65 cm, zoospores moved 35 cm behind the wetting front in sand, 44 cm in sandy clay loam, 48 cm in loam, and failed to move in silt loam soil. In the sand, sandy clay loam, and loam soils, matric potentials of −14.5, −18.4, and −16.2 mbars, respectively, were calculated for soil at the boundary between infested and noninfested soils. Zoospore cysts moved one‐half the distance zoospores did in each soil, respectively. The matric potentials associated with their boundary were −13.2, −13.4, and −12.0 mbars. Serratia marcescens cells were recovered close behind the wetting front in the first three soils but 48 cm behind in the silt loam. The matric potential 48 cm behind the wetting front was −33.5 mbars. Attempts were made to develop a predictive model for infiltration of biological propagules based on propagule size and soil moisture characteristic curves. Results indicated that infiltration of propagules occurred after soil pores with radii considerably larger than a priori estimates of the limiting pore radii were filled with water.
Ionic Activity Product of Calcium Carbonate Precipitated from Soil Solutions of Different Degrees of Supersaturation
Authors: Levy Rachel 
Published: July 2010

AbstractCalcium carbonate (CaCO3) was precipitated by equilibrating samples of calcareous soil and noncalcareous soil with a dilute sodium bicarbonate solution at two soil‐to‐solution ratios. Different degrees of supersaturation of the soil solutions prior to precipitation were thus achieved by releasing variable amounts of exchangeable calcium (Ca). Six sequential equilibrations were performed on each soil at each soil‐to‐solution ratio. Both Ca and magnesium (Mg) were released from exchange sites during equilibration, but mainly calcium carbonate precipitated. Precipitation in the soil extracts actually occurred if the degree of saturation after precipitation was lower than the degree of saturation prior to precipitation. The logs of the lonic activity product of calcium carbonate, pIAPc, of the noncalcareous soil were 7.57 and 7.83, and of the calcareous soil, 7.78 and 7.86, at the 1:1 and 1:10 soil‐to‐solution ratios, respectively. These pIAPc values were within experimental error of those obtained from undersaturation at a 1:1 soil‐to‐water ratio (Levy, 1981). The same pIAPc values were obtained regardless of the path by which equilibrium was approached, apparently because the same inhibitors were present in each case.
Nutrient Diagnosis in Corn Grown on Hydric Dystrandepts: I. Optimum Tissue Nutrient Concentrations
Authors: Escano C. R. , Jones C. A. , Uehara G. 
Published: July 2010

AbstractThe Benchmark Soils Project is an internationally based research project testing the hypothesis that agricultural technology can be transferred from one location in the tropics to another in soils of the same family. Environmental conditions and maize hybrids used in the tropics differ from those in temperature and subtropical regions. These factors can Influence the “adequate range” or “critical” tissue nutrient concentrations at which acceptable crop growth is obtained. The use of incorrect criteria for diagnosis of nutrient deficiencies from plant tissue analyses could result in inaccurate fertilizer recommendations. The objectives of this study were to evaluate several methods of determining adequate ranges and critical earleaf concentrations for a single maize hybrid grown on Hydric Dystrandepts in Hawaii and to compare the results with published data for other locations.Four methods of determining the optimum ranges of tissue nutrient concentrations were compared using data from eight N × P and seven CaCO3 × P fertilizer experiments. Optimum concentrations or ranges were calculated as follows: (A) the range of nutrient concentrations associated with the highest 5% of all plot grain yields; (B) the range of nutrient concentrations within one standard deviation of the mean concentration of the highest 15% of all plot yields; (C) the nutrient concentration at 95% of the maximum yield; and (D) the nutrient concentration which, when used as the critical concentration, resulted in the highest percentage of correct diagnoses of nutrient deficiencies. Methods (A) and (B) were used to determine optimum concentrations and ranges of N, P, K, Ca, Mg, S, Al, Mn, Fe, Cu, and Zn. Methods (C) and (D) were used for N and P only.Except for N, Mg, and S, the optimum ranges calculated by methods (A) and (B) were similar and were within previously reported sufficiency ranges for malze (Zea mays L.). For N, Mg, and S, high maize grain yields were found at concentrations slightly lower than those previously reported. The optimum concentrations of N and P obtained by methods (C) and (D) were similar and fell well within published ranges.In seven N × P experiments, highly significant positive correlations were found between both tissue N and P concentrations and grain yield. Likewise, the concentrations of tissue K, S, Cu, and Zn were often positively correlated with tissue N and P concentrations and with grain yield. Only Mn had a consistent negative correlation with grain yield and earleaf N concentration.
Coating of Calcium Carbonate on Gypsum Particle Surfaces
Authors: Keren R. , Kauschansky P. 
Published: July 2010

AbstractThe coating of calcium carbonate on gypsum particle surfaces was examined by electron microprobe technique. The gypsum‐carbonate interaction was studied in two systems: (i) gypsum‐sodium carbonate and (ii) gypsum‐calcareous soil. In both systems, the calcium carbonate was precipitated on the gypsum particle surfaces, forming a coating layer.
Elimination of Aerobic Degradation During Characterization of Pesticide Adsorption—Desorption in Soil
Authors: Koskinen W. C. , Cheng H. H. 
Published: July 2010

AbstractTwo methods for elimination of aerobic pesticide degradation during characterization of pesticide adsorption‐desorption in soil were compared, using 2,4,5‐T (2,4,5‐trichlorophenoxyacetic acid) as the test compound. Steam sterilization of soil significantly decreased 2,4,5‐T adsorption by soil, and degradation of 2,4,5‐T became noticeable after three days of desorption. Conducting the adsorption‐desorption process under a nitrogen atmosphere resulted in little change in 2,4,5‐T adsorption characteristics and negligible degradation even after six days of desorption.
Electromagnetic Determination of Soil Water Content Using TDR: II. Evaluation of Installation and Configuration of Parallel Transmission Lines
Authors: Topp G. C. , Davis J. L. , Annan A. P. 
Published: July 2010

AbstractTime‐domain reflectometry (TDR) applied to parallel transmission lines in soil was used to measure the soil water contents during infiltration, drainage, evaporation, and rising water table conditions in a 1.05‐m column of silt loam soil in the laboratory. Three types of installation and several types of transmission lines were evaluated. Comparisons of volumetric water content from gravimetric samples and from TDR showed differences were always <0.03 cm3cm−3. Trends of the TDR values with time showed that these differences likely resulted from soil density variations. Neither the installation method nor the design of the rods of the transmission line affected the water content values, provided there was good electrical contact with the soil. Transmission lines with discontinuities gave an effective and efficient measure of the soil water‐content profile.
Constant‐Flux Infiltration from a Hemispherical Cavity
Authors: Clothier B. E. , Scotter D. R. 
Published: July 2010

AbstractExisting theories of Raats, Parlange, and Warrick describing constant‐flux absorption and infiltration from hemispherical cavities are reviewed. A simple theory for absorption is derived, using the flux‐concentration relation of Philip. Three‐dimensional infiltration experiments are described that were used to test these theories. The results showed that infiltration at 360 ml/h into a 4‐mm‐radius hemispherical cavity in a repacked fine sand was described quite well by the simple absorption theory for the first 100 min. Beyond this time, at this flux, the effects of gravity became evident, as expected from a comparison of the matric and gravitational potential gradients. The nonlinear, steady‐state infiltration theory of Raats gave reasonable estimates of the water content profiles behind the wet front. The linearised (constant diffusivity) theory of Warrick was of no value in this context. The success of the Raats theory adds some credence to the use in trickle irrigation design of the Wooding's theory which describes infiltration from a circular pond on the basis of the same assumptions.
The Apparent Solubility of Calcium Carbonate in Soils
Authors: Suarez D. L. , Rhoades J. D. 
Published: July 2010

AbstractSoils in the laboratory were reacted with agricultural drainage‐ and distilled waters at various carbon dioxide (CO2) levels. The soil water solutions yielded different ion activity product (IAP) values than that of calcite, depending on experimental technique and whether calcite “equilibrium” is approached from supersaturation or undersaturation. Sample storage conditions affected IAP values as did partial pressure of CO2 and soil/water ratio. With sufficient reaction time all soil waters became supersaturated with respect to calcite—but to different degrees. The only calcium carbonate (CaCO3) phase detected in these soils was low Mg calcite. Calcium carbonate particles isolated from the soils gave IAP values expected for calcite (10−8.45 to 10−8.49). The calcite supersaturation in soil appears to be due to the presence of silicates in the soil more soluble than calcite, and is not the result of unstable CaCO3 phases. It thus appears inappropriate to try to determine the solubility of soil CaCO3 by reacting soil containing CaCO3 and water in the laboratory. Since soil‐ and drainage waters are not in equilibrium with calcite (or any other CaCO3 phase), calcite solubility is inappropriate for arid land soil‐water models. It is likely that the kinetic factors controlling soil solution composition under field conditions are not simulated by conventional types of laboratory experiments.
Gypsum Dissolution and Sodic Soil Reclamation as Affected by Water Flow Velocity
Authors: Keren R. , O'Connor G. A. 
Published: July 2010

AbstractThe dissolution rate of gypsum fragments in aqueous solutions was studied for Ca‐soil‐gypsum mixtures at two gypsum contents and four soil water velocities. Equations were derived to estimate the dissolution rate coefficient of gypsum fragments at different soil water velocities for a given surface area of gypsum. The soil water velocity controls both the time in which an elemental volume of water is moving in the soil‐gypsum layer and the dissolution rate coefficient. Increasing the soil water velocity increased the dissolution rate coefficient but decreased the contact time between an elemental volume of water and a unit of surface area of the gypsum fragments; the net effect is that increasing the water velocity decreases the gypsum dissolution rate. The effect of contact time on gypsum dissolution rate is much greater at the higher soil water velocity range than at the lower range. The soil water velocity also has a significant effect on sodic soil reclamation. The slower the soil water velocity, the higher the efficiency of replacing Na+ by Ca2+. The probable reasons for these findings are discussed.
Nitrate Reduction in Spartina Alterniflora Marsh Soil
Authors: Smith C. J. , DeLaune R. D. , Patrick W. H. 
Published: July 2010

AbstractThe transformation of nitrate (NO‐3) was investigated in flooded Louisiana Gulf Coast salt marsh soll. Nitrate formed in the aerobic zone of the soil is readily reduced in the deeper anoxic zone by dissimilatory and/or assimilatory processes. The experiments were conducted in soil cores 15 cm in diameter by 12 to 15 cm in depth. 15N‐labelled NO‐3 at 0.6 g N m−2 was administered in either a single injection into the floodwater or in repeated small injections below the sediment‐water interface. For the single application experiment, 14% of the 15N remained in the system; 4% NH+4‐N and 10% organic N. This implies dissimilatory reduction, with NO‐3 being reduced to NH+4 prior to formation of organic N. Fifty separate applications increased the recovery of 15N in the NH+4‐N and organic N pool to 52%. The latter procedure more nearly reproduces the low steady‐state concentration of NO‐3 observed in salt marsh soil; the increased recovery suggests that the internal inorganic‐N cycling in these soils may be more efficient than previously reported.
Flow of Kaolinite and Sewage Suspensions in Sand and Sand‐Silt: II. Hydraulic Conductivity Reduction
Authors: Swartzendruber D. , Uebler R. L. 
Published: July 2010

AbstractThe reduction in satiated (near‐saturated) hydraulic conductivity of fine quartz sand and sand‐silt (95% fine quartz sand and 5% quartz silt) for the flow of stable water suspensions of kaolinite clay and sewage solids was investigated in vertical flow columns. An equation was derived theoretically in which hydraulic conductivity is expressed as an exponential function of the cumulative volume of suspension inflow, and that contains a characterizing constant, termed the clogging coefficient, which is zero when water alone is the flow liquid. The equation was verified by experimental measurements. For a given suspension, the clogging coefficient was larger for sand‐silt than for sand, and of a given porous medium was larger for kaolinite suspension than for sewage suspension, but was not significantly affected by the initial water content (air‐dry or satiated) of the porous medium. The clogging coefficient offers promise as a criterion for the design of land‐application sewage systems and as a parameter for describing soil crusting caused by the infiltration of muddy water.
Predicting Loblolly Pine Growth Response from N Fertilizer, using Soil‐N Availability Indices
Authors: Lea Russ , Ballard Russ 
Published: July 2010

AbstractMineralizable nitrogen (N) fractions extracted from surface soil by 2N KCl, anaerobic or aerobic laboratory incubation, autoclaving, and dilute acid were not significantly correlated to five‐year volume growth response to N fertilization, site index, or N levels of foliage or litterfall. Site index was significantly and directly correlated to foliar N concentrations and inversely correlated to the surface soil C/N ratio. The amounts of N extracted by anaerobic and aerobic laboratory incubations could be significantly predicted, using total soil N and soil acidity.
Residual Value of Lime and Leaching of Calcium in a Kaolinitic Ultisol in the High Rainfall Tropics
Authors: Friesen D. K. , Juo A. S. R. , Miller M. H. 
Published: July 2010

AbstractA long‐term experiment was conducted on a highly acidic (pH 4.6), coarse‐textured Ultisol (Typic Paleudult; loamy, siliceous, isohyperthermic) in the high rainfall region of southeastern Nigeria in order to evaluate the requirement for and residual value of lime [Ca(OH)2] to a continuous crop rotation, and to determine the fate of applied Ca in the soil profile. The initial lime rates used were 0, 0.5, 1, 2, and 4 t of Ca(OH)2 per hectare. Maize (Zea mays) was planted in the first season and cowpea (Vigna unguiculata) in the second season under a no‐tillage, stubble conservation system.Results from the six‐year experiment indicate that relatively low rates of lime are adequate to sustain yields in a continuous maize‐cowpea rotation system. Liming at a rate of 0.5 t/ha maintained maize yield near maximum for 2 years after application. Sustained maize yields for 5 years or more were possible with a lime rate of 2 t/ha. The critical level of exchangeable Al required for 90% maximum yield of maize was about 35%. Cowpeas performed well and showed strong tolerance to soil acidity when planted as a late second‐season crop after maize without additional fertilizer application. The critical level of exchangeable Al ranged from 25 to 55% depending upon rate of chemical fertilizer as well as cowpea variety used.Leaching losses of Ca from the surface soil during the first 3 years were <0.5 t/ha of Ca(OH)2‐equivalents in the 0‐ to 2‐t/ha treatments. But an equivalent of 1.6 t/ha of lime was leached from the surface soil of the 4‐t/ha treatment suggesting that the mobility of Ca in this soil is a consequence of the hydrolysis of the pH‐dependent charge in the presence of acidifying nitrogeneous fertilizer.Exchangeable‐Al saturation in all subsoil layers of all treatments 3 years after liming exceeded 40% and soil pH (H2O) was <4.3 indicating that lime was leached as neutral Ca salts and had little effect in ameliorating subsoil acidity. Soil profile analysis after 3 years showed that nearly all Ca applied may be found within the 90‐cm depth. However, recycling of the leached Ca from the subsoil would require deep‐rooting species tolerant to high Al levels.
The Effect of Sodium Carbonates' Presence on the Soil Extract's Chemical Composition
Authors: Nadler Arie , Magaritz Mordeckai 
Published: July 2010

AbstractIt is shown experimentally that some sodic soils contain difficult‐to‐detect Na carbonate minerals which affect the chemical compositions of their aqueous extracts. Upon extraction with water, a portion of the dissolved HCO‐3 reacts with Ca2+ initially present in the soil (in a solid phase or occupying exchange sites) and is immediately precipitated as CaCO3. This phenomenon reduces extract pH and alkalinity (by precipitation of CaCO3 and release of CO2 gas) which obscures the initial presence of alkalinity.
Storage of Nitrous Oxide on Molecular Sieves
Authors: Duxbury J. M. , Voghel S. 
Published: July 2010

AbstractA procedure was developed for storing the N2O in 50‐mL air samples on activated molecular‐sieve type 5A in 60‐mL serum bottles. The procedure was equally effective for N2O concentrations of 1 and 10 µL · L−1 and storage times up to 6 weeks. Blank values for sieves stored 3 to 5 months after activation ranged from about 0.04 ± 0.002 to 0.05 ± 0.005 µL · L−1. Allowing freshly activated sieves to cool in air before capping the bottles increased blank values and variability to unacceptable levels. Nitrous oxide fluxes from soil > 10 g N · ha−1 · d−1 could be reliably determined when the storage procedure was used in conjunction with a chamber method for N2O flux measurement.
A Technique for Rapid Removal of Gypsum from Soil Samples
Authors: Rivers E. D. , Hallmark C. T. , West L. T. , Drees L. R. 
Published: July 2010

AbstractRemoval of gypsum from soil samples is necessary to disperse soils for particle‐size analysis or clay separation for mineralogical study. A technique utilizing the heating of gypsiferous soil overnight at 105°C is presented. The heat treatment converts gypsum to bassanite which is more soluble than the gypsum and the disruption of the gypsum upon dehydration also yields bassanite particles which can easily be crushed to provide a greater surface area. Subsequently, the time required to remove gypsum from soil by dialysis is reduced by >50%. Heating the samples did not change the clay mineralogy or the cation exchange capacity, but did result in slightly higher total and fine clays and slightly lower sand contents.
Nonsymbiotic Nitrogen Fixation in an Oak‐Hickory Forest Following Long‐Term Prescribed Burning
Authors: Vance E. D. , Henderson G. S. , Blevins D. G. 
Published: July 2010

AbstractSeasonal rates of nonsymbiotic nitrogen fixation in the surface soil of oak‐hickory forest plots exposed to 30 years of annual and periodic (4‐year) prescribed burning were estimated using an in‐situ acetylene reduction procedure. Fixation rates were low, averaging 0.1 kg·ha−1·year−1 for all soil cores assayed in April, August, and October 1980 and April 1981 with approximately 11% of samples displaying activity. Burning treatments had no influence on fixation rates or proportion of samples displaying activity. Highest rates were found in autumn with an average rate for active samples of 2.2 kg·ha−1·year−1. Higher autumn fixation rates may be related to higher quantities of high energy foliar leachates which could induce a significant seasonal peak on sites demonstrating higher rates of fixation.