bluuebunny/crossref_metadata_2025_split huggingface dataset:
Clover Residue Effectiveness in Reducing Orthophosphate Sorption on Ferric Hydroxide Coated Soil
Authors: Easterwood G. W. , Sartain J. B. 
Published: July 2010

AbstractIn many tropical soil systems, secondary minerals are coated with sesquioxides, resulting in inherently low P availability to plants due to P‐fixation mechanisms. Research was conducted to determine the influence of hydroponically grown clover (Trifolium repens L.) residue pretreatment in reducing orthophosphate sorption on a fine‐loamy, siliceous, thermic Typic Paleudult (Orangeburg series) that had been coated with synthetically prepared amorphous Fe(OH)3. A 3 × 2 × 3 factorial experiment was conducted in split‐split‐plot design with P as the main plot, Fe(OH)3 as the subplot, and clover as the sub‐subplot. Throughout two cropping periods of 50 d each, to assess the initial and residual effect of clover pretreatment, corn (Zea mays L.) dry‐matter yield, P uptake, and Bray 2 extractable P levels were superior with clover pretreatment prior to P fertilizer addition. When fertilizers, but not clover, were again applied to experimental units for a third cropping period, clover pretreatment did not influence plant dry‐matter accumulation or P uptake. It did, however, substantially increase Bray 2 extractable P levels. Potentiometric titrations relating to surface charge were conducted on treatments with Fe(OH)3 that had been amended with P, clover, and P plus clover after the first cropping period. Results suggest that organic acids from clover decomposition bind to Fe(OH)3 surfaces and are able to complex Lewis acid cations to increase P availability.
Ammonia Volatilization from Nitrogen Fertilizer Surface Applied to Orchardgrass Sod
Authors: Lightner J. W. , Mengel D. B. , Rhykerd C. L. 
Published: July 2010

AbstractIf the N needs of the grass sward cannot be met with a compatible legume, then additional N inputs must come from other sources, such as urea, to sustain high yields. However, urea is difficult to incorporate in an established grass pasture, which can result in considerable inefficiencies in N utilization. One cause of this inefficiency is volatilization of NH3. Field measurements were made to determine the amount of NH3 lost through volatilization from urea‐based fertilizers surface broadcast onto an orchardgrass (Dactylis glomerata L.) sod on a Xenia silt loam soil (a fine‐silty, mixed, mesic Aquic Hapludalf). Nitrogen sources used were: urea applied as both a granular solid product and as a solution; cogranulated urea‐urea phosphate (UUP); ammonium nitrate (AN); and urea‐KCL and urea‐CaCl2 solutions at a cation/urea‐N equivalency of 0.50 KCl or 0.25 CaCl2·2H2O. Fertilizer N was applied at 200 kg N ha−1 in the spring and 100 kg N ha−1 in late summer. Measurable NH3 loss occurred within 12 to 24 h after N application. Rate of volatilization was greatest from mid‐morning to early afternoon. Highest NH3 losses were from solid urea, urea solution, and urea‐KCl solutions. Losses from these materials ranged from 27 to 41% of applied N in the spring and from 12 to 37% in the summer. No significant volatilization losses were observed with AN. Ammonia losses from UUP were significantly less than those from solid urea in the spring, and at least 40% less in the late summer. Relative to urea solution alone, mixing CaCl2 with urea lowered volatilization significantly in both 1983 studies. Finally, the concentration of KCl with urea in this study did not effectively reduce NH3 volatilization.
A Volume Recorder for Lysimeter Waters
Authors: Hazlett P. W. , Foster N. W. , English M. C. 
Published: July 2010

AbstractWater moving through the soil can be sampled by a variety of lysimeters, but in many cases the volume of water exceeds the capacity of the collection vessel. The design of a simple and inexpensive volume recorder used to measure large volumes of soil water from individual lysimeters is presented. During tests in the field, the volume recorder provided good estimates of water volumes collected by tension‐free lysimeters. The compactness and easy portability of the unit makes it ideal for year‐round use at remote field locations to determine variability in the flow of soil water.
Phosphorus Chemistry and Mineralogy in Excessively Fertilized Soils: Descriptions of Phosphorus‐rich Particles
Authors: Pierzynski G. M. , Logan T. J. , Traina S. J. , Bigham J. M. 
Published: July 2010

AbstractData is limited on the mineralogical characteristics and formation mechanisms of P‐bearing solids that occur in soils due to P fertilization. This study was conducted to characterize, isolate, and infer formation mechanisms for P‐rich particles found in two excessively fertilized soils. Phosphorus‐rich particles were described in terms of morphology, elemental composition, and crystallinity using electron optical techniques. These particles were found in the <2.2 Mg/m3 density separates from the clay fractions of a Plainfield loamy sand (mixed, mesic Typic Udipsamment) and Blount silt loam (fine, illitic, mesic Aeric Ochraqualf) that had been excessively fertilized for more than 20 y. Particle morphologies indicated that the P‐rich materials exist as discrete particles as well as coatings on other particles. The elemental composition of the particles varied within as well as between particles. Phosphorus concentrations in the P‐rich materials ranged from 5.6 to 27.2% per mole of cation (mole cation%). Aluminum and Si were the dominant elements associated with P, while Ca, Fe, and Mn generally were present at low concentrations. The P‐rich materials were amorphous to electron diffraction and can generally be described as an amorphous mixed Al‐Si‐P substance. An analogy was made between the P‐rich materials, the amorphous analog of variscite, and allophane.
A Rapid Method for Total Nitrogen Analysis Using Microwave Digestion
Authors: He X. T. , Mulvaney R. L. , Banwart W. L. 
Published: July 2010

AbstractA microwave digestion procedure recently proposed for total N analysis of soil using HF‐HCl, H3BO3, and H2O2 was found to give much lower values than conventional Kjeldahl digestion in analysis of soil and plant samples and simple organic N compounds. An alternative microwave procedure was developed that involves Kjeldahl digestion with concentrated H2SO4 and a K2SO4‐catalyst mixture. With this procedure, digestion of five samples can be accomplished in 30 min. Complete recovery (≥98%) of N was obtained in analysis of several organic N compounds. Total N analyses of plant materials by the microwave Kjeldahl method agreed closely with those by conventional Kjeldahl digestion using an Al block; the microwave method gave somewhat lower results than the conventional method for surface soils with a high content of total N. Precision of the analysis was comparable for both methods. Recovery of N added to soil as NO3 averaged 97% when the microwave procedure was modified to include a pretreatment with salicylic acid and sodium thiosulfate. Although much more rapid, the microwave Kjeldahl method is not necessarily more convenient than conventional digestion with an Al block because of the need for frequent loading and unloading of samples.
Locating Sampling Sites for Salinity Mapping
Authors: Rhoades J. D. , Lesch S. M. , Shouse P. J. , Alves W. J. 
Published: July 2010

AbstractAn evaluation of the suitability of a commercial long‐range navigation (LORAN‐C) method to locate and determine mapping coordinates of soil salinity sites was made in California field trials. The LORAN‐C‐determined position was within 16 m of the true position 90% of the time. This is sufficient accuracy to locate sampling areas identified with Système Probatoire d'Obervation de la Terre (SPOT) satellite imagery (pixel resolution of 30 m), but not for locating smaller sampling areas, such as those identified in low‐altitude photographs. The LORAN‐C method proved suitable for producing regional salinity maps that could resolve soil‐salinity differences on a scale of 200 m.
Estimation of Water‐Retention Function Using Scaling Theory and Soil Physical Properties
Authors: Daamen Carl C. , Robinson James A. , Xiao Zhenhua 
Published: July 2010

AbstractEstimation or measurement of water‐retention functions is an important part of studies of water balance in soils. Characterization of a spatially variable water‐retention function, S(h), where S is degree of saturation, is demonstrated here with a data set from a 2‐ha watershed. The soil is classified as Shepparton fine sandy loam. Four common functional forms for S(h) were fitted to the data set using scaling theory and nonlinear regression. Initially, only one model parameter, associated with a scaling factor, was fitted independently to each core. This scaling approach accounts for most of the variability (e.g., r2 = 0.975) and an estimate of the residual in S is within the accuracy of field measurement. Using nonlinear regression and fitting both parameters independently does improve r2 (= 0.991), but only marginally. Using the scaling approach, an expression of soil physical properties was used in place of the independent parameter. The regression (r2 = 0.967) gives values to the coefficients of physical properties in this expression, allowing scale factors to be calculated directly from physical properties. A jack‐knife estimation technique was employed to show how well scale factors are calculated from physical properties alone. This methodology accounted for spatial variability adequately, offering a simple, computationally efficient representation in numerical simulation. Other data sets indicated that approach may be useful on a regional scale for clearly defined soil groups.
Soil Phosphate Diffusion Coefficients: Their Dependence on Phosphorus Concentration and Buffer Power
Authors: Bhadoria P. B. S. , Kaselowsky J. , Claassen N. , Jungk A. 
Published: July 2010

AbstractMeasured values of effective P diffusion coefficients, De, were compared with De values calculated on the basis that P only diffuses in the liquid phase. Two soil blocks differing in P content were placed into contact for 2 wk, then quick frozen and cut into slices of 0.2 mm with a refrigerated microtome. The slices were extracted with 4 M HCl to obtain a P concentration‐distance curve. An average diffusion coefficient, D̅e, was determined from the total amount of P that had diffused from the soil of high P concentration to that of low P concentration. Effective diffusion coefficients for a given soil P concentration, Dec, were obtained by analyzing the concentration‐distance curve. Phosphorus buffer curves were established by adsorption in the lower concentration range and by desorption in the higher concentration range, according to the process occurring during P diffusion in soil. The value of D̄e increased from 2.2 to 13.9 × 10−13 m2 s−1 when the average soil P concentration increased from 380 to 580 mg P kg−1 soil. The Dec values increased with increasing P concentration, although the relationship was not unique. For example, the same Dec value of 5 × 10−13 m2 s−1 was obtained at 340 mg P kg−1 when P was being adsorbed and at 600 mg P kg−1 when P was being desorbed during the process of diffusion. This result was related to different P‐buffer behavior of the soil during adsorption and desorption. The P diffusion coefficient in soil is, therefore, dependent not only on the buffer power, which is influenced by concentration, but also on whether P is being desorbed or adsorbed and on the time available for reaction. The value of De can be calculated if suitable values for the buffer power are used, and De for a wide P‐concentration range can be calculated if a weighted average buffer power is used.
Sampling Strategies for Assessing Hydraulic Conductivity and Water‐Conducting Voids in Saprolite
Authors: Vepraskas M. J. , Hoover M. T. , Bouma J. 
Published: July 2010

AbstractA saprolite's saturated hydraulic conductivity (Ksat) and types of water‐conducting voids must be known to assess its suitability for liquid waste disposal. This study determined optimum numbers of pits and numbers of samples per pit needed to estimate a saprolite's Ksat and volume percentages of water‐conducting macrovoids and groundmass (microvoids). Three pits were dug across a 5‐ha area to expose B horizons and saprolite (2‐m depth), and undisturbed cores were collected from each pit. The Ksat was measured for each core, and water‐conducting voids were dyed. Volume percentages of water‐conducting (dyed) macrovoids (e.g., root channels with diam. ≥0.1 mm) and water‐conducting groundmass were determined from thin sections. Mean values for saprolite Ksat and volume percentages of water‐conducting macrovoids and groundmass were 0.25 cm h−1 and 1.1 and 47.9%, respectively. In order to minimize both the variance of each mean value and the time required for analysis, it was most efficient to collect only one core per pit. The most efficient number of pits depended on the desired size of the confidence interval and the property of interest. A 95% confidence interval for saprolite Ksat that was within 10% of the true mean would require over 700 pits per 5 ha, while an estimate of the percentage of water‐conducting groundmass would require only 10 pits per 5 ha. Increasing the width of the 95% confidence intervals to be within 50% of the means reduced the required number of pits for these properties to 28 and 1, respectively.
Water Quality Effects on Soils and Alfalfa: I. Water Use, Yield, and Nutrient Concentration
Authors: Prunty Lyle , Montgomery B. R. , Sweeney M. D. 
Published: July 2010

AbstractThe detrimental effects of salt buildup in northern Great Plains soils need quantification. This study was conducted to evaluate effects of irrigation water quality on alfalfa (Medicago sativa L.) yield, water use, and nutrient concentration during a 21‐mo period. Irrigation waters of seven qualities, totaling 4400 mm in wet/dry cycles, were applied to 20 by 60 cm undisturbed soil columns under green‐house conditions. Four loam soils representing moderate to moderately slow permeable drainage classes were used. The soils were: Williams loam (fine‐loamy, mixed Typic Argiboroll), Barnes loam (fine‐loamy, mixed Udic Haploboroll), Svea loam (fine‐loamy, mixed Pachic Haploboroll), and Parshall loam (coarse‐loamy, mixed Pachic Haploboroll). Effects of soil, water quality, and time on yield and water use were highly significant (R2 = 0.94*** [*** denotes significance at P = 0.001] and 0.93***, respectively). In all soils and waters, yield and water use decreased 30 to 60% by the end of the experiment. Mean nutrient concentrations, with the exception of Na, remained within 10% of the original values. Irrigation water with sodium adsorption ratio (SAR) of 20 and ionic concentration of 20 mmolc L−1 increased the alfalfa Na concentration to 15 times that with distilled irrigation water. Total Na added accounted for 84%*** of variation in relative yield. One‐half of the salt‐induced yield reduction appeared in the first third of the experiment. This underscores the inadvisability of irrigating with poor‐quality water that might be available during drought periods.
Surface Sealing in Coastal Plains Loamy Sands
Authors: Radcliffe D. E. , West L. T. , Hubbard R. K. , Asmussen L. E. 
Published: July 2010

AbstractSoil surface seals may consist of a dense surface skin seal and/or a washed‐in layer of dispersed clay just below the surface. Work in Israel has shown that when clay contents are below about 20%, the seals that form are relatively permeable. In Georgia, soils of the Piedmont region with clay contents above 10% can form low‐permeability seals. Our objective was to determine if the more sandy soils of the Coastal Plain region would form seals and, if so, to describe the morphology of these seals. Infiltration was measured using a rainfall simulator on bare and straw‐covered tilled soil at six sites on three loamy sands. The three soils used were Tifton (fine‐loamy, siliceous, thermic Plinthic Kandiudult), Carnegie (clayey, kaolinitic, thermic Plinthic Kandiudult), and Clarendon (fine‐loamy, siliceous, thermic Plinthaquic Paleudult). Final infiltration rates were significantly lower in the bare soil at all but one site, indicating that sealing occurred. Final infiltration rates were not as low as those observed in soils from the Piedmont region of Georgia, probably due to the lower clay content of the Coastal Plains soils. Thin‐section micrographs suggested that these seals formed due to surface disruption with raindrop impact. Although grains that had been stripped of clay and oxides were observed at the surface, no distinct zones of clay and oxide concentration (washed‐in layers) were observed. Size and spatial relationships of the areas of stripped grains suggested that they had been transported and redeposited rather than developed in place.
Oak Influence on Nutrient Availability in Pine Forests of Central Arizona
Authors: Klemmedson James O. 
Published: July 2010

AbstractExisting evidence suggests that Gambel oak (Quercus gambelii Nutt.) improves soil fertility of the ponderosa pine (Pinus ponderosa Dougl. ex Laws) forest of central Arizona. Greenhouse bioassays were conducted to determine if Gambel oak also influences nutrient availability in the 0‐ to 15‐cm mineral soil layer. Barley (Hordeum vulgare L. cu. Gustoe) and pine seedlings were grown to estimate availability of N, P, K, and S in soils from 15 pine stands with basal area of oak varying from 0 to 62% of the total basal area, but equivalent in all other site factors. Without supplemental nutrients, barley yield from soils with 50% oak was three times greater than from those with no oak. With addition of N, P, K, and S, barley yield increased 370% on soils without oak, but only a 50% yield increase occurred on soils from stands with 50% oak. Regression analysis of barley yields for each nutrient revealed that availabilities of N and S were significantly related to amount of oak present. Availabilities of P and K were not related to oak presence. The bioassay with pine seedlings confirmed that oak positively influenced N supply. This test, however, showed no effect on S supply. Contrasting results for barley and pine tests are attributed to greater sensitivity of barley and high variance in the pine test.
Net Erosion on a Sagebrush Steppe Landscape as Determined by Cesium‐137 Distribution
Authors: Coppinger K. D. , Reiners W. A. , Burke I. C. , Olson R. K. 
Published: July 2010

AbstractSoil erosion plays a major role in structuring landscapes of semiarid regions. The purpose of this study was to examine patterns and assess transport mechanisms of soil erosion and deposition in a native sagebrush steppe landscape in south central Wyoming using 137Cs. Six landscape units were identified using a cluster analysis based on four landscape variables. Cesium‐137 values varied little among landscape units, suggesting that intermediate‐scale (approximately 100 m) fluvial and eolian soil transport is unimportant in this system during the time since bomb‐test 137Cs deposition occurred. In contrast, analysis of variance showed that, on windswept landscape positions, 137Cs was significantly higher under shrubs than between them. These differences suggest that wind‐driven redistribution has occurred at a small scale (0.5–10 m). Even though 137Cs data indicate that intermediate‐scale transport is not occurring, analysis of the soil fine fraction across the landscape shows net transport of fines downslope, suggesting that, in this sagebrush ecosystem, soil redistribution by fluvial erosion occurs too slowly to be determined by 137Cs.
Suspension Nebulization Analysis of Clays by Inductively Coupled Plasma‐Atomic Emission Spectroscopy
Authors: Laird D. A. , Dowdy R. H. , Munter R. C. 
Published: July 2010

AbstractUse of suspension nebulization for elemental analysis of clays by inductively coupled plasma‐atomic emission spectroscopy (ICP‐AES) was evaluated to ascertain the effects of particle size and various experimental parameters on total recoveries. To do so, specimens of Grundite illite and Georgia kaolinite no. 3 were fractionated by centrifugation to prepare samples of the <0.2‐, 0.2‐ to 2‐, 2‐ to 10‐, and 10‐ to 45‐µm size fractions. Portions of these samples were dispersed in 1 M HNO3 or 0.1 M NaCl and analyzed by ICP‐AES using suspension nebulization. Other portions of the samples were digested with HF and analyzed by ICP‐AES using solution nebulization. Total recoveries were determined by comparing the sum of all oxides for the suspension‐ and solution‐nebulization analyses. Total recoveries ranged from 2 to 100% depending on particle size of the samples, design of the spray chamber, observation height, carrier Ar pressure, sample nebulization rate, and method of sample preparation. Incident power of the plasma did not substantially affect total recoveries. The highest total recoveries were obtained by sonicating samples for 10 min at 80 W in 0.1 M NaCl, and by maximizing sample nebulization rate (2.6 mL min−1), minimizing carrier Ar pressure (1.52 mPa), and using a conical spray chamber for the analyses. For the <0.2‐ and 0.2‐ to 2‐µm size fractions, these conditions yielded reproducible results with total recoveries >90%. Total recoveries for the 2‐ to 10‐ and 10‐ and 45‐µm size fractions, however, never exceeded 70 and 24%, respectively. Therefore, suspension nebulization is not recommended for use with samples containing particles larger than 2 µm. Use of suspension nebulization with ICP‐AES, however, is a rapid and reliable method for performing multielement analyses of clay (<2‐µm) samples.
A Unique Soil‐Carbonate Liberation Technique for Use with Carbon‐14‐Labeled Carbonate
Authors: Sheppard Marsha I. , Schwartz W. J. 
Published: July 2010

AbstractA fast, inexpensive, and efficient method was developed to liberate 14C‐labeled CO3 from soil, and trap the evolved 14C‐CO2 in vials ready for liquid scintillation counting. The apparatus is fabricated with microanalytical materials that minimize the contact surfaces and total internal gas volume. Another advantage is that the trapped CO2 is directed immediately into the counting vial, ready for analysis. Recoveries of standard additions to soil were always >97% and usually 99.9%. Comparison of this method with a similar direct CO2‐absorption method, now being used to radiocarbon date hydrological and geological samples, proves this method gives results similar to the traditional methods. Recoveries from non‐carbonated and carbonated (6% CO3) soil cores, spiked to simulate entry of contaminated groundwater, support the usefulness of this method for 14C soil‐transport studies.
Modified Calibration Procedure for the Measurement of Microbial Sulfur in Soil
Authors: Castellano S. D. , Dick R. P. 
Published: July 2010

AbstractTo better estimate S biomass in soils, an alternative calibration technique for the measurement of microbial biomass S in soil was developed. Rather than using pure cultures of bacteria and fungi to determine the biomass‐S calibration constant (Ks), cultures of bacteria and fungi were grown using soil dilutions as primary inoculum. These microorganisms were harvested and washed, and dense suspensions of bacteria or fungi (in 0.15 M NaCl matrix solution) were prepared. The suspensions were used as inoculum for the calibration procedure, where bacteria or fungi were each grown at three S concentrations (1, 4, or 16 mg SO4‐S L−1) and subsequently added to soil and fumigated with CHCl3. The mean value of 39.3% was calculated for the proportion of microbial S extracted with calcium phosphate [8 mM Ca(H2PO4)2] from a Woodburn silt loam (a fine‐silty, mixed, mesic Aquultic Argixeroll) following CHCl3 fumigation. This procedure may better reflect the soil microbial biomass than using pure cultures, because soils have mixed microbial populations.