bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lime Induced Magnesium Stress in Corn: Impact of Magnesium and Phosphorus Availability
Authors: Grove J. H. , Sumner M. E. 
Published: July 2010

AbstractPrevious research has indicated that lime additions to soils with variable surface charge resulted in reductions in measures of “exchangeable” Mg. The potential loss of Mg from “plant available” soil phases was evaluated in two greenhouse trials. These experiments were conducted in 1979 and 1980 to evaluate the potential for Mg nutritional problems in corn [Zea mays (L.) Merr.] grown on a Bradson clay loam (Typic Hapludults) over a wide range in soil pH and plant available P and Mg. Bulk soil samples were taken from each of three lime rate treatments in a field trial last amended with dolomite in 1967. In the first experiment three levels of lime and P were imposed in a complete factorial combination on each bulk sample. In the second experiment, the bulk soil sample with the lowest native level of extractable Mg was amended with eight rates of lime and two rates of Mg in a complete factorial combination. Increased Mg availability was associated with increased tissue Mg concentrations and shoot dry matter productivity. Added lime generally decreased extractable soil Mg, tissue Mg, and shoot dry matter. Applied P reduced “overliming” stress in the first experiment. Magnesium, P, and Zn were implicated in the nutritional stress associated with lime induced yield depressions.
Uniformity of Nitrogen‐15 Enrichment in Different Plant Parts and Subsequent Decomposition Monitoring of Labeled Crop Residues
Authors: Wagger M. G. , Kissel D. E. , Smith S. J. 
Published: July 2010

AbstractIn order to accurately evaluate the N mineralization from decomposing crop residue, residue should be uniformly labeled, i.e., it should contain a relatively constant atom % 15N in all N compounds within the plant. Our objective in this study was to estimate the uniformity of 15N labeling by comparing the 15N content of different plant parts of winter wheat (Triticum aestivum L.) and grain sorghum [Sorghum bicolor (L.) Moench]. Labeling with 15N was accomplished by applying a single, highly enriched but low rate of N to the soil early in the growth stage of the respective crops. Small enclosed microplots were used for incorporating the 15N enriched fertilizer into the initial crop and for following decomposition in subsequent years. At crop maturity, recovery of the initial K15NO3 application avg. 71.9% for all soil texture‐crop combinations. Data from the 15N labeling study indicated that relatively uniform enrichment of various plant parts was obtained when K15NO3 was applied to the soil at the jointing and eight‐leaf stages for wheat and sorghum, respectively. On average, atom % 15N values for all plant parts ranged from 6.962 to 8.171 and 2.801 to 3.274 for winter wheat and sorghum, respectively. These results imply that segregation of 15N‐labeled plant material into various plant parts for use in subsequent crop residue decomposition experiments is unnecessary.
Automated Analysis of Nitrite, Nitrate, and Ammonium Nitrogen in Soils
Authors: Markus D. K. , McKinnon J. P. , Buccafuri A. F. 
Published: July 2010

AbstractAutomated procedures are presented for determining NO‐2‐N, NO‐3‐N, and NH+4‐N in various soil testing programs. An AutoAnalyzer system equipped with a microprocessor‐based controller and data handler was employed in the study. The new system, through its drift, gain, and carryover correction features, provides improvement in accuracy and precision of results. Further, the new system also has the potential for more rapid chemical determination. The evaluation of accuracy and precision of NO‐3‐N and NH+4‐N analyses, studied in standard solutions and determined with the automated system at 60, 90, and 120 h−1 sampling rates, is presented. Results of NO‐2‐N, NO‐3‐N, and NH+4‐N analyses in nutrient solutions of hydroponic culture, as well as in extracts of mineral soils and peat‐based greenhouse substrates, determined with the automated procedure at the 90 h−1 sampling rate, are also presented. Moreover, the total N content and cation exchange capacity of mineral soils determined by NH+4‐N analysis with the AutoAnalyzer at the 90 h−1 sampling rate are also shown. Analyses performed by automated procedures are compared with those obtained by a nonautomated colorimeter for all samples used in the study. Nitrite nitrogen and NO‐3‐N were determined by hydrazine reduction, and NH+3‐N was determined as indophenol in both the automated and nonautomated procedures. Also, the threshold concentration levels of interfering ions determined in aqueous standard solutions of NO‐2‐N, NO‐3‐N, and NH+4‐N are presented.
Mineralization of Nitrogen from Nitrogen‐15 Labeled Crop Residues Under Field Conditions
Authors: Wagger M. G. , Kissel D. E. , Smith S. J. 
Published: July 2010

AbstractThe management of crop residues and their contribution to the supply of plant nutrients is intimately tied with N cycling in the soil. Any attempt to utilize crop residues to the fullest extent requires an understanding of how the system functions. The objective of this research was to determine the extent and rate of N mineralization from 15N‐labeled winter wheat (Triticum aestivum L.) and grain sorghum [Sorghum bicolor (L.) Moench] residues. In addition, the influence of soil texture and fertilizer N on net N mineralization also was evaluated. Nitrogen mineralization from decomposing crop residues was followed by means of plant and soil sampling during subsequent cropping seasons. Plant N uptake and soil inorganic N data showed that 12 to 15% of wheat residue N and 12 to 33% of sorghum residue N were mineralized after one cropping season. Net mineralization differences between crop residues may be attributed to both the C/N ratios and chemical composition of these plant materials. Soil texture and the addition of fertilizer N mainly influenced the initial rate of mineralization, particularly with the wheat residue. There was also evidence of N immobilization of the recently mineralized 15N followed by remineralization later in the growing season for wheat and sorghum residues decomposing in the medium‐textured soils. This immobilization occurred during a period of rapidly increasing soil temperatures. On avg, 79% of the mineralized wheat residue N and 82% of the mineralized sorghum residue N were utilized by wheat and sorghum plants, respectively. Based on these results, the greatest proportion of N mineralized from decomposing wheat and sorghum residues appears to coincide with plant N demand by the subsequent crop, irrespective of differences between C/N ratios of these residues or soil texture.
Use of Soil Survey Data for Regional Soil Water Simulation Models
Authors: Wösten J. H. M. , Bouma J. , Stoffelsen G. H. 
Published: July 2010

AbstractA detailed soil survey of an area of 650 ha was used to obtain basic soil physical data for a simulation model of the water regime in the unsaturated zone. Nine major soil horizons were defined for the entire survey area in terms of pedological classification and easily measurable characteristics such as texture, structure, organic matter content, and bulk density. In these horizons multiple measurements of hydraulic conductivity and moisture retention curves were made, yielding average curves. Statistical comparison of the curves showed that only five of the nine major soil horizons were different from a soil‐physical point of view. Next, representative soils for the mapping units were transformed into soils composed of a characteristic sequence of some of these five horizons. In this way a simulation map, containing data to be used for simulation of the soil water regime, was formed from the soil map. For a sample area of 125 ha the simulation map contained 41 delineated areas as compared to 110 delineations on the soil map. Sixty independent test borings indicated 80 ± 6% purity comparing borings and the legend of the simulation map. A simulation run for one pedon with the model SWATRE showed excellent agreement between measured and calculated actual evapotranspiration for the years 1976, 1977 and 1978. Major soil horizons, rather than individual points of observation, were used in this study as carriers of soil physical information, allowing extrapolations based on a limited number of measurements.
Acidification Sources in Red Alder and Douglas Fir Soils‐Importance of Nitrification
Authors: Van Miegroet H. , Cole D. W. 
Published: July 2010

AbstractPrecipitation, throughfall, forest floor, and soil leachate samples were monitored continuously in 1981 and 1982 in a N‐poor Douglas‐fir [Pseudotsuga menziesii (Mirb.) Franco] forest and a red alder (Alnus rubra Bong.) forest growing adjacently on a glacial soil in western Washington. The purpose of the study was to quantify the relative importance of atmospheric vs. natural sources of H+ input to forest soil acidification, and to determine the role of N transformation processes in the overall H+ balance of soils with different N status. Rainwater samples had an avg pH of 4.7 and annual H+ deposition via precipitation averaged 320 mol H+ ha−1 yr−1. This was modest compared to internal H+ production associated with HCO‐3 and NO‐3 formation. In the soil under alder cover, which was naturally enriched in N through symbiotic N2‐fixation, nitrification released up to 4500 mol H+ ha−1 annually to the solution percolating through the upper part of the soil profile. In the N‐poor soil no nitrification could be observed and N transformation processes had a minor influence on the soil H+ balance. The main internal acidification source in this case was H2CO3 dissociation releasing 420 mol H+ ha−1 yr−1. In both instances, soil solutions appeared well buffered against these external and internal acidification sources, and few H+ leached below the 40‐cm soil depth.
Embryonic Halloysites in Ecuadorian Soils Derived from Volcanic Ash
Authors: Wada Koji , Kakuto Yasuko 
Published: July 2010

AbstractA unique mineral association that represents embryonic stages of halloysite formation in weathering of andesitic volcanic ash was found in three Ecuadorian soils which did not contain allophane. This mineral association consisted of more or less poorly ordered halloysites and a “1.0‐nm mineral”. The more poorly ordered halloysite was nearly x‐ray amorphous and showed infrared (IR) absorption bands which were characteristic of halloysite but poorly resolved. It was dissolved congruently (Si/Al ratio = 1.0–2.0) by hot M/3 sodium citrate solution and incongruently (Si/Al ratio = 0.37–0.40) by 0.2 M ammonium oxalate‐oxalic acid (pH 3.0). The 1.0‐nm mineral and the less poorly ordered halloysite were not dissolved by these reagents. The former was not distinguished from the latter on the IR spectra and both had a Si/Al ratio of, or close to, 1.0. The 1.0‐nm mineral showed, however, a broad 1.0‐nm reflection not only at 25 but at 300°C and even at 550°C. Embryonic halloysites varied in morphology from thinly spread flakes to elongated, rolled thick plates, and spherical particles. Soils containing the more poorly ordered halloysites with Si/Al ratios of ca 1.5 to 2.0 and 1.0 showed a low and a fairly high “Al reactivity”, respectively. It was inferred that embryonic halloysites have formed in base and silica rich environments. Structural schemes of the 1.0‐nm mineral and the more poorly ordered halloysite were discussed.
A Suction Apparatus for Orienting Clay Minerals Onto Porous Ceramic Tiles
Authors: LaManna John M. , Bowers Fred H. 
Published: July 2010

AbstractA new design is presented for an apparatus that makes oriented mounts for the x‐ray study of clay minerals. The apparatus can be easily fabricated by drilling and tapping holes into a metal plate and adding standard screws, nuts, pipe fittings, and plastic funnels. The main advantages of this design are (i) ease of fabrication, (ii) the ability to deposit clay cakes of almost any diameter onto tiles of almost any shape or size, and (iii) the incorporation of a relatively large sample reservoir that will hold enough suspension to allow the operator to perform other tasks while the tiles are being prepared.
Field Calibration and Validation of Solute Transport Models for the Unsaturated Zone
Authors: Jury William A. , Sposito Garrison 
Published: July 2010

AbstractData from two solute transport field experiments, one obtained from soil solution samplers and the other from soil coring, are used to illustrate the parameter estimation problem for two models describing area‐averaged vertical transport of mobile solutes. The two models, the lognormal transfer function model (TFM) and the convection dispersion equation (CDE), were selected because of their simplicity and because they represent different hypotheses for the governing mechanisms determining longitudinal solute spreading on the field scale. The two parameters of each model are estimated using three calibration procedures: sum of squares optimization, method of moments, and maximum likelihood. The three calibration procedures yield different estimates for the parameters using a given data set, and different trends in parameter variation at different depths or times in a given experiment. Calculated uncertainty in the parameter estimates was high enough that no conclusion could be drawn about which model better described the data from the solution sampler experiment, but the TFM provided a better description of the coring experimental data after calibration than the CDE. It was concluded that future experiments on field scale solute transport through the unsaturated zone will have to monitor movement below 5 m in order to yield a data set suitable for distinguishing between different models.
A Simple Method for Combining Soil Properties that Show Variability
Authors: Addiscott T. M. , Wagenet R. J. 
Published: July 2010

AbstractA method is shown by which variable soil properties expressed by distributions may be combined to estimate a variate that is derived from them through some functional relationship. The probability distribution (normal, log‐normal, or any other form) of the input for each property is divided into sections, each having the same number of observations. The section medians for each property are then combined through the functional relationship in all combinations of section and property to generate a population of values for the required variate without presupposing any particular type of distribution for it. The method gave estimates of unsaturated hydraulic conductivity, K(θ), that agreed with those from the Taylor series method (Rao et al., 1977) and additionally showed a marked increase in the variance of K(θ) as the volumetric moisture content, θ, decreased. Because the method generates a population of θ values, it could be further shown that as θ decreased, K(θ) became less well described by a log‐normal distribution. It can be used for nondifferentiable functions and, as is demonstrated for water flux calculations, functions whose inputs are log‐normally distributed but which cannot be expressed in logarithmic form. Although the method is not equivalent to the Monte Carlo procedure, it gave estimates of water flux that differed little from those given by Monte Carlo simulations.
Ionic Transport in Soil with Ion‐exchange Reaction
Authors: Cho C. M. 
Published: July 2010

AbstractA mathematical model describing the transport of two ions in an exchange material such as soil, was described. Concentration profiles of displacing ion, A, and an ion being displaced, B, were obtained using the numerical solution of the two simultaneous transport equations of A and B. The variations in the concentration distributions were investigated by varying the selectivity coefficient of ion exchange reactions, valences of A and B, the magnitude of incoming concentration, and cation exchange capacity under constant flow rate of soil solution and dispersion coefficient. The results of the analyses indicated that the concentration distributions of displacing and displaced ions within a soil column can be related to the selectivity coefficient of the ion exchange reaction, exchange capacity, and concentration of the displacing ion. As the ion exchange selectivity coefficient became large, the front of the displacing ion became sharper and the maximum concentration of the displaced ion became greater. The depth of penetration of the displacing ion was not great since the ion effectively replaced the native ion that resided on the exchanger phase. For divalent‐monovalent exchange, the cation exchange capacity, selectivity coefficient, and concentration of the displacing solution played a role in determining the shape of the distribution curves of displacing and displaced ions.
Kinetics of Calcite Dissolution as Affected by Carbon Dioxide Partial Pressure
Authors: Amrhein C. , Jurinak J. J. , Moore W. M. 
Published: July 2010

AbstractResearch was conducted to determine the effect of CO2 on the kinetics of soil mineral dissolution. It was found that in soils or overburden materials in which CaCO3 is the dominant weatherable mineral, the kinetics of dissolution was not a simple diffusion controlled or first‐order reaction. In these calcareous systems, the transfer of atmospheric CO2 to solution was an important rate limiting step in the kinetics of dissolution. At higher PCO2 values the dissolution of calcite was modeled by three simultaneous reactions on the surface of the calcite. It is postulated that the CO2 attack consists of an adsorption of CO2(aq) on the calcite surface followed by hydrolysis of the CO2 to H2CO3. The hydrolysis is apparently catalyzed by the calcite surface because the aqueous hydrolysis, CO2(aq) + H2O → H2CO3, occurs too slowly for the observed rate of reaction.
Estimating Net Nitrogen Mineralization from Carbon Dioxide Evolution
Authors: Gilmour J. T. , Clark M. D. , Sigua G. C. 
Published: July 2010

AbstractThe ability to estimate net N mineralization from C decomposition data has the potential to improve our understanding of N dynamics in soil systems. It was the objective of this study to study this relationship using substrates with varying decomposition rates and C/N ratios. Five substrates including sewage sludge, alfalfa (Medicago sativa L.), clover (Trifolium sp.), bermudagrass [Cynodon dactylon (L.) Pers.] and ryegrass (Lolium multiflorum Lam.) were incubated in Crowley silt loam (Typic Albaqualfs) or Captina silt loam (Typic Fragiudults) soil at known soil temperatures and moistures. Concurrent CO2 evolution and soil inorganic N concentrations were measured periodically. A significant linear relationship between N mineralization and CO2 evolution was found experimentally for each substrate. A computer simulation model was developed which used first order kinetics for conversion of substrate C to CO2. Substrate C mineralization rate constants, substrate C/N ratios and microbial efficiency were primary inputs, while substrate, biomass, and soil organic matter were the major compartments of the model. Microbial efficiency was defined for any C pool undergoing decomposition as the ratio of assimilated C to assimilated C plus dissimilated C. An important feature of the approach was the introduction of a fraction with a C/N ratio of protein that decomposed very rapidly for those substrates where initial N mineralization was large while CO2 evolution was small. Model predictions of both CO2 evolution and net N mineralization were in good agreement with experimental results.
Effects of Potassium and Magnesium Applied for Corn Grown on an Irrigated Sandy Soil
Authors: Rehm G. W. , Sorensen R. C. 
Published: July 2010

AbstractWhile the sandy soils of the Nebraska Sandhills and bordering areas are inherently low in N, P, and S, the levels of K and Mg in many soils are considered to be marginal. This study was conducted to evaluate the effects of repeated application of K and Mg on: (i) grain yield of corn, (ii) concentration of K and Mg in plant tissue, and (iii) soil test values for K and Mg. This study was conducted in north‐central Nebraska from 1979 through 1982 at a site that was marginal with respect to K and Mg. The soil was classified as a Valentine loamy fine sand (Typic Ustipsamments, mixed, mesic). Twenty treatment combinations from a 92 complete factorial were selected to fit a central composite factorial design and replicated 3 times. Selected rates of K (0, 34, 67, 101, 134, 168, 202, 235, 269 kg ha−1) and Mg (0, 5.6, 11.2, 16.8, 22.4, 28.0, 33.6, 39.2, 44.8 kg ha−1) were broadcast and incorporated before planting. Whole corn plants were collected from each plot when plants were 40‐ to 60‐cm tall and the leaf opposite and below the ear was sampled each year. These tissue samples as well as samples of grain were analyzed for K and Mg. Grain yields were measured each year. The application of both K and Mg had no significant effect on yield throughout the study. Although the concentrations of K and Mg were marginal as indicated by routine soil test procedures, this soil was apparently able to supply adequate K and Mg for corn production. Soil test values for K and Mg increased linearly with the rate applied. A yearly application of 33 kg K ha−1 was satisfactory for maintaining the initial level of soil test K. The K concentration in both whole plant and ear leaf tissue increased linearly with rate of K applied. In general, the K concentrations in the ear leaf tissue were in excess of the published critical level of 19 g kg−1. The Mg concentration in the plant tissue increased linearly with rate of applied Mg but decreased curvilinearly as the rate of K was increased. The Mg levels were substantially higher than published critical levels.
Energy Dissipation for Water Drop Impact into Shallow Pools
Authors: Ferreira Alfredo G. , Singer Michael J. 
Published: July 2010

AbstractThe literature reports that the presence of a shallow layer of water over the soil during a rainfall event is associated with more soil loss than the sum of the soil loss produced by rainfall and overland flow separately. The mechanism for this increase in raindrop effectiveness is not fully understood. We photographed, at 1000 frames s−1, the splashes of 3.2‐mm diam drops that were falling at close to terminal velocities into static water. During impact crater closing, soil from the pool bed was lifted. Energy calculations showed that the kinetic energy during crater closing generally reached a larger value than during crater opening. This may be responsible for the lifting of soil particles that were disaggregated during drop impact and crater formation and explain why a shallow water layer over the soil surface increases the erosive efficiency of raindrops.
Increases in Extractable Ions in Infertile Aquults Caused by Sample Preparation
Authors: Gilliam F. S. , Richter D. D. 
Published: July 2010

AbstractEffects of sample preparation on dilute acid‐extractable ions were measured for paired unground field‐fresh and ground air‐dried soil samples taken from three depths at two sites in the coastal flatwoods of South Carolina. Concentrations of most extractable ions for the two preparation methods correlated closely. However, grinding and air‐drying increased extractable NO‐3 concentrations by 6 to 10 times, NH+4 and PO3‐4 2 to 3 times, and base cations up to 2.5 times. Ion releases from grinding and drying soils in the laboratory are related to soil organic matter and to field changes in soil moisture depletion.