bluuebunny/crossref_metadata_2025_split huggingface dataset:
Zinc and Copper Sorption and Fixation by an Acid Soil Clay: Effect of Selective Dissolutions
Authors: Cavallaro N. , McBride M. B. 
Published: July 2010

AbstractCopper and zinc sorption‐desorption studies were carried out over a range of pH values using clay fractions separated from two horizons of an acid soil from New York. In the pH range of high sorption, as much as 95% of the sorbed metal could not be desorbed by several washes with 0.05M CaCl2 and thus was considered fixed. Sorption and fixation of Cu and Zn increased rapidly above pH 4 and 5, respectively, for the whole soil clays. Following removal of the oxide fraction by oxalate and citrate‐dithionite extractions, sorption and fixation were reduced considerably at pH values below the onset of hydrolysis of the metals in bulk solution, indicating a significant role of the oxides in metal retention. Citrate‐dithionite extraction was more effective than oxalate in reducing Zn sorption and fixation, suggesting a significant influence of the more crystalline iron oxide fraction. These extraction procedures had less effect on the ability of the clays to sorb and fix Cu. Treatment of the clays by hypochlorite to remove organics tended to either enhance or have little effect on sorption and fixation of Cu and Zn. It is concluded that microcrystalline and noncrystalline oxides in the clay fraction of this soil, representing < 20% of the clay by weight, provide reactive surfaces for the chemisorption of Cu and Zn. At low pH, adsorption at these surfaces may be the dominant mechanism of heavy metal immobilization, especially in the subsoil horizons.
Identification of Two Dominant Serotypes of Rhizobium trifolii in Root Nodules of Uninoculated Field‐Grown Subclover
Authors: Demezas D. H. , Bottomley P. J. 
Published: July 2010

AbstractAnalysis of the protein profile patterns by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS‐PAGE) of 30 isolates of Rhizobium trifolii obtained from root‐nodules of uninoculated field grown plants of subclover (Trifolium subterraneum L.) cv. ‘Mt. Barker’ showed that 12 and 9 isolates were represented by two different protein profile patterns (gel types). Serological analyses performed using antisera raised to one isolate of each gel type showed that although the two isolates, 1‐01 and 2‐01, shared a common antigenic determinant, they were distinguishable by their reactions in whole‐cell somatic agglutination and gel‐immune‐diffusion tests. Forty‐nine of the sixty isolates collected from nodules in the establishment year, and 56 of 90 isolates collected the following year were antigenically identical to either one or the other of the two parent isolates. Sixteen of the one hundred fifty isolates cross‐reacted strongly with both antisera in whole‐cell somatic tube agglutination and gel‐immune‐diffusion assays while only 23 of the 150 isolates were antigenically unrelated to either 1‐01 or 2‐01. All of the 22 isolates of serotype 1‐01 collected in the establishment year possessed the same gel type, wheres 19 of 27 isolates of serotype 2‐01 had the same gel type as the parent isolate, 2‐01. The majority (18 of 22) of isolates of serotype 1‐01 were superior symbiotic effectiveness while the majority (17 of 19) of isolates of serotype 2‐01 possessing the same gel type were of inferior effectiveness.
Prolificacy in Corn: Its Effects on Nitrate and Ammonium Uptake and Utilization
Authors: Pan W. L. , Kamprath E. J. , Moll R. H. , Jackson W. A. 
Published: July 2010

AbstractCorn (Zea mays L.) genotypes differing in prolificacy were evaluated for N uptake and utilization from NO‐3 and NH+4 sources. Five single‐cross hybrids which differed in capacity to produce more than one ear per plant were field grown to maturity on a Dothan loamy sand (plinthic Paleudults), with two different N sources, calcium nitrate, or urea plus nitrapyrin. The two N sources were applied at two rates, each in multiple applications throughout the growing season. This minimized (i) the magnitude of nitrification within the urea treatments, and thereby enhanced the supply of N in the NH+4 form to the plants grown under the urea treatment, and (ii) differences in N availability due to differential leaching rates of NH+4 and NO‐3. At the low N supply there was little difference in N uptake or grain yield between the two N sources. At the high N supply, genotypes that produced > 1.5 ears per plant absorbed more N from the urea treatment and produced more dry matter during ear development. These increases were associated with an enhanced grain yield over the comparable NO‐3 treatment. Fully prolific plants demonstrated greater remobilization of N from vegetative tissue to grain. However, they also showed a lesser capability to absorb N during ear development, particularly from the NO‐3 source. The latter trait may have limited yields as indicated by the enhanced grain production in these genotypes when grown with a NH+4 source.
Characteristic Variations in Spectral Reflectance of Selected Eroded Alfisols
Authors: Latz K. , Weismiller R.A. , Van Scoyoc G.E. , Baumgardner M.F. 
Published: July 2010

AbstractSoil cores taken at incremental depths from a Typic Hapludalf were examined to investigate the relationships among the chemical, physical, and spectral reflectance properties which occur as the proportion of various horizons change in the soil samples. Results of these studies were compared to soil samples taken from selected Typic Hapludalfs in Indiana which represented various degrees of natural erosion. Two important properties affecting the spectral reflectance of these soils were the organic matter and iron oxide contents. High organic matter contents tend to cause the reflectance to be low and give a concave character to the spectral response in the 0.5‐ to 0.8‐µm region. High iron oxide content along with the reduction in organic matter tends to cause an increase in the overall spectral response; however, the presence of iron oxides causes a leveling off of the spectral response in the 0.8‐ to 1.1‐µm region. Intermediate contents of organic matter and iron oxide affect the spectral response relative to their proportions within the soil sample. These distinctive reflectance characteristics can be related to the severity of erosion. Comparison of laboratory data to simulated Landsat data suggests that satellite multispectral scanner data can be useful in detecting eroded soils. Separability of erosion classes for the Alfisols studied was best determined by observing the slope of the simulated Landsat plots between 0.75 and 0.95 µm, bands 3 and 4. As the severity of erosion increases, the slope of the plot decreases in this region.
Stored Available Soil Water and the Fallow/Recrop Decision—Critical Level Approach
Authors: Goos R. J. , Johnson B. E. , Sobolik F. J. , Schneider R. P. 
Published: July 2010

AbstractThe amount of stored soil water at seeding has long been appreciated as a critical factor in the success of annual spring wheat (Triticum aestivum L.) production in the semiarid region of the Northern Great Plains. Stored available soil water at seeding, growing season precipitation, and grain yield data from 53 spring wheat experiments in western North Dakota were analyzed by both multiple regression and an interaction chi‐square approach. Soil types were generally fine‐loamy, mixed Typic Haploborolls or Argiborolls. Regression equations explained to little of the variability of the data to be useful in drawing practical guidelines for future fallow/recrop decisions. The results suggest that stored soil moisture data are better analyzed by the interaction chi‐square test, the results of which provide easy‐to‐interpret guidelines for making future fallow/recrop decisions. For example, for a minimum acceptable recrop wheat yield of 1350 kg/ha, the following critical levels were defined: stored available soil water at seeding less than 6.4 cm, crop failure is likely and summerfallow is advised; stored available soil moisture 6.4 to 9.4 cm, approximately equal odds of crop failure or success; stored available soil moisture > 9.4 cm, crop success is likely and recropping is advised.
Effects of Fresh and Decomposing Corn Plant Residue Extracts on Corn Seedling Development
Authors: Yakle G. A. , Cruse R. M. 
Published: July 2010

AbstractEarly corn (Zea mays L.) growth is frequently reduced in tillage systems that leave large amounts of corn residue on or near the soil surface. This effect may be due, in part, to the release of phytotoxic chemicals from the residue during rainfall or microbial breakdown. Laboratory experiments were conducted to investigate the activity of corn residue phytotoxins after movement through soil by using a corn seed bioassay for measurement. Corn seeds were germinated in tap water solutions extracted from corn residues that had been incubated with or without soil for 0, 15, or 30 d under wet, poorly aerated conditions. The extracted corn residue solutions were then either filtered or not filtered through columns of sterilize soil before being used to germinate the seeds. The corn seedlings were grown without light for 7 d in a growth chamber maintained at 22°C. A tap water check treatment was included in the study. Extracts of corn residue incubated without soil resulted in 39% as much root growth as did the check treatment. Incubation of the residue with soil reduced the inhibitory effects of the extracts, as did filtration of the corn residue extracts through the sterilized soil columns. The results suggest that phytotoxins extracted from corn residues incubated with soil were inactivated in the soil by microbial breakdown. Phytotoxins, however, were able to move through the sterilized soil columns without significant alteration of their inhibitory properties.
Use of Pressurized Vials for Loading Sample Loops in Soil Gas Analyses
Authors: Stealey T. E. , Hern J. L. , Harner E. J. 
Published: July 2010

AbstractA technique was developed using small (3 mL) evacuated glass vials for soil gas sample storage and loading of gas chromatographic sample loops. Vial volume was reduced 2 mL by inclusion of glass beads. The vials were pressurized with 3.2 mL sample and used directly for loop loading via a specially contructed vial guide. Time course determinations on stored samples of C2H2 and Kr indicated leak losses of 0 to 0.2% d−1 when compared to the ideal technique of exhaustive loop purging from a standard gas tank. The low cost, reusability, and known vacuity of the vials, as well as the elimination of a transfer stop from storage container to a syringe prior to injection into a gas chromatograph, should favor their use in agronomic field and laboratory studies where numerous samples of the smallest possible volume must be taken.
Ion Products and Solid‐Phase Activity to Describe Phosphate Sorption by Soils
Authors: Blanchar R. W. , Stearman G. K. 
Published: July 2010

AbstractSolution equilibria and regular solid‐solution concepts were combined to relate phosphate solubility to amounts of added phosphate in eight acidic Missouri soils. Phosphate sorption studies were done by shaking KH2PO4 solutions with soil for 16 d and measuring pH, Eh, electrical conductivity, Ca, Mn, Al, Fe, and P contents of the solution. These data were used to compute ion products and to estimate the activities of solid‐phase phosphate minerals. It was shown that solubility relationships for the reaction of H2PO4 with Al(OH)3 could be interfaced with estimates of solid‐phase activities and used to predict phosphate in solution as a function of a soil constant (C), soil pH, and the amount of phosphate added. Activities for the equilibrium equation,p(H2PO4) = 10.50 − pH − p[Al(OH)3] + p(AlPO4),were estimated. The value of p[Al(OH)3] was determined from the data to be a linear function of pH, 2.41 − 0.42 pH, for soils used in this study. The value of p(AlPO4) was determined by statistically fitting observed p(AlPO4) and Padded to a polynomial equation similar in form to the one for a regular solid solution:p(AlPO4) = C − 9.4 × 10−3 (Padded) + 6.9 × 10−6 (Padded)2,with r2 = 0.96. Values of p(H2PO4) were calculated from pH and Padded by these combined equations, and compared with measured p(H2PO4) with an r2 of 0.96. The system was shown to have solubility features similar to those described for a regular solid solution. Combining solution equilibria and regular solid‐solution concepts was useful in providing a chemical basis for interpreting phosphate sorption by soils.
Distribution of Applied Nitrogen in Soil—Pensacola Bahiagrass Components as Indicated by Nitrogen‐15
Authors: Impithuksa V. , Blue W. G. , Graetz D. A. 
Published: July 2010

AbstractThe fate of fertilizer N applied to coarse‐textured soil‐plant systems is not well understood. To determine the effects of N rates and seasonal N applications on plant response and recovery of applied N from these soils, three field experiments with 15N‐enriched fertilizer were superimposed in 1976 on nontracer N experiments on Myakka fine sand (sandy, siliceous, hyperthermic Aeric Haplaquods), Ona fine sand (sandy, siliceous, hyperthermic Typic Haplaquods), and Astatula sand (hyperthermic, uncoated Typic Quartzipsamments) planted to Pensacola bahiagrass (Paspalum notatum Flugge). At each site, a split‐plot experimental design was used with two N rates (100 and 200 kg ha−1) as main plots and three seasonal N applications as subplots. Forages, stolon‐root masses, and soils were analyzed for total N and 15N concentrations. In 1976, forage yields and 15N‐labeled fertilizer N contents were larger at the higher N rate, but were not affected by seasonal N applications. Recovery of fertilizer N in forage was 36, 31, and 29% for the Myakka, Ona, and Astatula soils, respectively. An average of 48% of the total N in forage was from the fertilizer. Mineralization of immobilized N from previous fertilizations probably did not account for the large amount of nonfertilizer N in the forage. Recoveries of fertilizer N in stolon‐root masses were 11, 11, and 16%; recoveries in soils were 28, 13, and 11%; and recoveries in soil‐plant systems were 74, 54, and 54% from the Myakka, Ona, and Astatula soils, respectively. Denitrification was suspected as an important N loss mechanism from the poorly drained Myakka and Ona soils, and leaching was likely dominant from the well‐drained Astatula soil; however, soil‐solution samples collected from depths of 60 and 120 cm in these soils showed no evidence of N leaching. Not more than 5% of the 15N‐labeled fertilizer applied in 1976 was recovered in forage produced in 1977. At the end of 1977, total fertilizer N accounted for was essentially the same as at the end of 1976. Two important results were the relatively large amounts of nonfertilizer N in forage, especially in 1976, the year of 15N‐labeled fertilizer application, and the relatively high percentage of fertilizer N retained in these three sandy soils. In 1983, 7 yr after fertilization with labeled N, there was little change in labeled N in the soil compared to 1977.
A Soil Test for Nitrogen Availability to Corn
Authors: Magdoff F. R. , Ross D. , Amadon J. 
Published: July 2010

AbstractA soil test for N availability to corn (Zea mays L.), NO‐3‐ to 30cm when plants are 15 to 30 cm tall, was evaluated on a wide range of soils at 33 locations in Vermont and one in New York state. The NO‐3‐N present at the time of sampling is a result of an integration of all the soil and weather factors that have influenced the availability of N prior to the time for sidedress fertilizer application. There was a typical response relationship between soil test NO‐3‐N and corn silage yield on plots that only received limited amounts of starter N fertilizer at planting. The Cate‐Nelson procedure for NO‐3‐N vs relative yield (yield without sidedress N/yield with sidedress N) indicated that there was a greater probability of response to N fertilizer when NO‐3‐N was less than 36 kg ha−1 than at higher soil test values. The currently used N fertilizer recommendation procedure is based on estimates derived from cropping history, yield goal, soil type, and manure management information provided by farmers. Compared with the current method of estimating N fertilizer needs, recommendations based on the NO‐3‐N soil test call for much less N fertilizer application and are more accurate in separating sites with varying response probabilities. As a routine laboratory procedure, the proposed test has numerous advantages over other N availability procedures. However, special procedures are needed, including rapid soil treatment after sampling (to eliminate N transformations), sampling the soil at a different time than for the usual soil test, and a rapid sample turnaround time in the laboratory.
The Relationships of Landsat Digital Data to the Properties of Arizona Rangelands
Authors: Horvath E. H. , Post D. F. , Kelsey J. B. 
Published: July 2010

AbstractPedon descriptions, vegetation transect information, and Landsat digital data were obtained for 110 sites on the Tonto National Forest in central Arizona. Using the field and satellite data, 33 variables were evaluated and prediction models were generated using stepwise multiple regression techniques. The following six factors explained 84% of the variability within the sum of the values for the four Landsat spectral bands: sum of brush and forest crown densities, elevation, surface color, rock type, cobbles on the surface of the site, and grass cover. Seven factors explained 81% of the variability for the ratio of Bands 4 plus 5 to Bands 6 plus 7: percent clay in the surface horizon, percent fragments > 2 mm in the surface horizon, the sum of forest and brush crown densities, pH of the surface horizon, color of the surface horizon, litter cover, and site aspect.
A Simple Colorimetric Measurement for Humic Acids in Spodic Horizons
Authors: Holmgren G. G. S. , Holzhey C. S. 
Published: July 2010

AbstractAn organic buffer, 2‐amino‐2‐methyl propanol neutralized to pH 10 with 4M acetic acid, was investigated as an extractant for soil organic matter. The color of the humic acid fraction of this extract proved to be a distinctive marker of spodic horizon organic matter. Both the humic acid and fulvic acid fractions were quantified by a simple comparator used to classify color in natural waters. The fulvic acid color was functionally related to aluminum in the extract and also to aluminum in the pyrophosphate extract. If the extract contained iron, it was associated with the humic acid color, although humic acid color could be present without iron. The humic acid color was present only in those soils with pH < 4.5. Data are presented to demonstrate the ruggedness of the procedure with respect to variations of extraction time and of the soil/solution ratio.
Relation of Organic Carbon to Soil Properties and Climate in the Southern Great Plains
Authors: Nichols J. D. 
Published: July 2010

AbstractThe proportion of Mollisols in the Southern Great Plains ranges from 1% to > 90% of counties with completed soil surveys. A study was made on data from 65 pedons spaced as equally as possible across the area. All of the soils studied had grassland vegetation, were on uplands, were not excessively wet, and did not have high shrink‐swell potential. Stepwise multiple regression analyses were made on percent organic carbon vs. percent clay, percent silt, base saturation, mean annual precipitation, and mean annual temperature. Results indicate a significant relationship between organic carbon and clay with a lesser relationship with precipitation. The other variables did not improve the predictive equation.
Using Clay Mineralogy to Infer Sources of Suspended Clay and Silt in a Watershed: Quantitative Approach
Authors: Hsieh Y. P. 
Published: July 2010

AbstractA functional procedure for using clay mineralogy to infer sources of suspended clay and silt in a watershed is presented. The information could lead to estimation of soil loss from various parts of a watershed, if the dispersion factor of the source soils can be evaluated. The suspended clay and silt carried by the Gallatin River and its tributaries were used to illustrate the methodology. Clay mineralogy of the clay and silt is expressed as the relative percent peak heights of minerals from the x‐ray diffractogram. The percent peak heights of these minerals are found reproducible (CV = 6%), and additive in nature. Analysis of variance reveals that clay mineralogy is significantly different among the tributaries of the Gallatin River. The results of discriminant analysis substantiated that clay mineralogy can be a signature of the suspended clay and silt carried by the Gallatin River and its tributaries. The Q‐mode factor analysis technique was applied to “demix” the suspended clay and silt of the main stream into its source components. The results of Q‐mode factor analysis indicate that clay and silt carried by the Gallatin River was mainly from Taylor Fork (92%) on 7 May 1971. The source of clay and silt in Taylor Fork was further traced back to its upper‐stream above Wapiti Creek (90%). The source of suspended solids in West Fork varied according to the sampling dates. On 27 May 1971, the north and south branches contributed almost equal parts of that to West Fork, while on 8 June 1971, the south branch contributed the majority (84%) of clay and silt to West Fork. The proposed method of sediment tracing by clay mineralogy is relatively simple and economical compared to the conventional stream monitoring methods. More important, it provides an independent alternative to the conventional methods of soil erosion assessment in a watershed.
A Portable Tool for Obtaining Soil Cores in Clayey or Rocky Soils
Authors: Tuttle C. L. , Golden M. S. , Sirois D. L. 
Published: July 2010

AbstractA portable tool was designed to collect soil samples, root cores, and bulk density cores on remote forest sites. Use of the designed tool allowed soil cores to be collected repeatedly from a study plot with minimal site disturbance. Cores 7.62 cm in diameter and up to 45.0 cm deep were collected and analyzed. Up to 10 cores per hour can be obtained by a two‐man crew. Over 1000 cores were collected before maintenance of the tube was needed. Bulk density cores collected with the designed tool were not significantly different from cores collected using standard 7.62 cm rings.
A Generalized Solution to Infiltration
Authors: Warrick A. W. , Lomen D. O. , Yates S. R. 
Published: July 2010

AbstractA generalized solution to the moisture flow (Richards') equation is developed for infiltration. The equation is expressed in terms of dimensionless time, depth, and water content. The reduced form applies for the hydraulic functions of van Genuchten or of Brooks and Corey as well as to other scaled forms and the solution utilizes the procedure of Philip. Answers are presented in concise tables which, in principle, allow for finding moisture profiles, wetting front, intake rate and cumulative intake for a variety of soils and for varying initial water contents. For application, specifically measured hydraulic conductivities can be best‐fitted to the forms used here or generalized empirical values can be used from the literature. Thus, either specific or generic parameters may be used, depending on availability for a given problem.
Statistical Relationship between Apparent Dielectric Constant and Water Content in Porous Media
Authors: Ansoult M. , De Backer L. W. , Declercq M. 
Published: July 2010

AbstractA theoretical relationship between the apparent dielectric constant (Ka) and the water content (θr) of porous media is presented. The dielectric effect of the porous medium is investigated at the microscopic scale of the probable path of an electric charge. This path is a function of the environment of the charge. Only one parameter, the number of degrees of freedom of the charge is necessary to describe the heterogeneity of the porous medium. The results of this model generally agree very well with recently published experimental data.