bluuebunny/crossref_metadata_2025_split huggingface dataset:
Utilization of Fertilizer Nitrogen‐Nitrogen‐15 by Field‐grown Alfalfa
Authors: Feigenbaum Sala , Hadas Aviva 
Published: July 2010

AbstractAlthough legumes are usually not fertilized with N, response of irrigated alfalfa (Medicago sativa L.) to N fertilization has been observed frequently. More precise information is required, however, on the time and extent of the fertilizer‐N utilization by alfalfa and its distribution in the soil.Uptake of ammonium fertilizer by alfalfa, its rate of nitrification and its recovery in a clay and sandy soil, were studied under field conditions using labeled ammonium sulfate as a fertilizer source. The fertilizer, enriched to 10.28 atom % 15N, was applied to microplots, with and without plants, in a commercial alfalfa field at a rate of 100 kgN/ha. Plant tops were analyzed for total N and soil samples for mineral N. Excess 15N content in plants and soil was also determined.Alfalfa recovered 40 to 45% of the applied fertilizer during the whole growth period on both soils, but in the first cut the recovery was higher in the sandy than in the clay soil. The 15N atom % in the alfalfa indicated a large effect of fertilizer on N uptake in the first two cuts only.The decrease in NH4‐15N recovery in the soil with time during the first 20 days after fertilization was exponential, indicating first‐order kinetics of the nitrification process. The rate constant was 0.13 day−1 and the half‐life of ammonium in the field was 5 days, which is considerably faster than reported in the literature for laboratory incubation experiments at similar temperatures.
Extraction of Phosphatase, Urease, Proteases, Organic Carbon, and Nitrogen from Soil
Authors: Nannipieri Paolo , Ceccanti Brunello , Cervelli Stefano , Matarese Emilio 
Published: July 2010

AbstractExtractions of three soils at different incubation times demonstrate that 0.14M sodium pyrophosphate at pH 7.1 extracts phosphatase, urease, casein, and benzoylarginamide hydrolyzing proteases. Extraction yields of phosphatase and casein‐hydrolyzing proteases are remarkably high. The most efficient length of extraction depends both on the type of soil and on the selected enzyme.Correlation analyses of extracted enzymes and extracted C and organic N content generally show a significant correlation (p = 0.05 and 0.01).
Predicting the Most Efficient Phosphorus Placement for Corn
Authors: Anghinoni I. , Barber S. A. 
Published: July 2010

AbstractYield increase from P fertilizer application depends on the efficiency of utilization of the added P. Placing added P in part of the soil volume rather than mixing it with all the soil may increase P uptake because of less tie‐up of P by the soil, however, the degree of benefit from P placement has been difficult to predict. The objective of this paper is to use data from P placement experiments with corn (Zea mays L.) together with a simulation model to develop a procedure for estimating the P placement that will maximize P recovery and plant yield. The Claassen‐Barber simulation model gave predicted P uptake by corn that compared favorably with observed P uptake and hence was used in this study. The model uses parameters describing root growth and morphology, kinetics of P uptake, and kinetics of P supply by the soil. Measurements of corn root growth as affected by P placement, of P influx into corn roots as influenced by P concentration, and of soil P supply as affected by rate of P addition to three soils were used to provide data to use in the simulation model. Predicted P uptake by corn was calculated for a range of fractions of the soil volume treated with five rates of added P per pot for two soils and with one P rate on an additional soil. Uptake of P from P‐treated soil was added to uptake from untreated soil to get total P uptake. As the volume fraction of P treated soil increased from zero, calculated P uptake increased to a maximum then decreased with further dilution of added P with soil. The optimum fraction of the soil that had to be P‐treated to get the greatest predicted P uptake increased with rate of application. Where one rate was applied to three soils, the greater the adsorption of P by the soil, the lower the fraction of P‐treated soil needed to maximize P uptake. The principles illustrated in this paper may be useful for developing the most efficient fertilizer placement for crops grown in the field.
Soil Properties and Chemical Composition of Tree Leaves in Southern Indiana
Authors: Crum J. R. , Franzmeier D. P. 
Published: July 2010

AbstractSoils developed from gray‐green shale in southeastern Indiana and neighboring states have low forest site quality and low productivity for farm crops. In this study the Rarden soil, formed from gray‐green shale, was compared with the Trappist soil (moderately productive), developed from black carbonrich shale, and the Hickory soil (highly productive), developed from Illinoian till. The soils were on westerly‐facing shoulder and backslope landscape positions. Crystals occurring as small patches in the B3 of Rarden were identified as barite (BaSO4) in prismatic, hexagonal‐tabular, or octagonal‐tabular shapes. A pedon of the Rarden soil contained about two‐thirds as much extractable Ba as Ca. Leaves from three hardwood species were analyzed for 15 elements at each site. Flowering dogwood (Cornus florida L.) leaves accumulated Ca and, especially, Al to a much greater extent than sugar maple (Acer Saccharum Marsh) or white oak (Quercus alba L.), whereas sugar maple tended to accumulate Mn. Leaf samples collected in July and September showed no significant differences in concentration of the major nutrient elements P, K, and Ca, but did show differences in concentration of several of the minor nutrients. No evidence was found that Ba or other minor elements caused toxicities or deficiencies. The contents of extractable Ca and Al in the soil were reflected in their concentrations in flowering dogwood leaves.
A Variable‐Depth Ground‐Water Sampler
Authors: Galgowski C. G. , Wright W. R. 
Published: July 2010

AbstractAn inexpensive variable‐depth ground‐water sampler for 4‐cm i.d. PVC well casing is made from readily available materials. The sampler will extract water samples at any selected depth from a shallow aquifer via a perforated well casing without mixing water from different strata. Water samples can be obtained from a depth of about 10 m with standard vacuum equipment.
Estimating Critical Stress in Unsaturated Soils from Changes in Pore Water Pressure During Confined Compression
Authors: Larson W. E. , Gupta S. C. 
Published: July 2010

AbstractThe objective of this study was to describe the changes in pore water pressure as a function of initial soil water content and applied stress. A hypothesis is developed that relates pore water pressure of unsaturated soils during application of applied mechanical stress to changes in soil structure.During compression of unsaturated agricultural soils, the pore water pressure decreases to a minimum (becomes more negative), and then increases as the applied mechanical stress increases. The pore water pressure‐log applied stress curves for a given soil with different water contents are similar in shape but vary in scale. The degree of water saturation at which minimum pore water pressure occurs appears to be a constant for a given soil. This degree of saturation increases with soil clay content up to about 33% clay and then remains nearly constant at 0.60. The pore water pressure‐log applied stress curves for different water contents of a given soil, when normalized, fit a common curve. For different soils, the log of applied stress corresponding to the minimum pore water pressure, when normalized with respect to the log of stress at saturation, increases with clay content up to about 33% clay and then remains constant at 0.78. It appears that, as the applied stress increases beyond the point of minimum pore water pressure, soil aggregates are sheared and their integrity destroyed. The stress corresponding to the point of minimum pore water pressure is, we think, the maximum stress that should be applied to a soil during cultivation or by vehicular traffic. Finally, this paper describes a procedure for estimating the critical stress for other soils from a soil's clay content using the relationships developed in this study.
Coupling Phenomena in Saturated Homo‐ionic Montmorillonite: IV. The Dispersion Coefficient
Authors: Groenevelt P. H. , Elrick D. E. , Laryea K. B. 
Published: July 2010

AbstractThe movement of NaCl through the clay paste examined in this series of articles is analyzed in terms of dispersion and convection. The dispersion coefficient is proven to be velocity independent, i.e. the “hydrodynamic/lateral diffusion” part of the dispersion coefficient is negligible in comparison to the “molecular‐diffusion” part.Subsequently the thermodynamic equations for the salt flux and the liquid flux are reformulated for the condition of zero electric current. The salt flux equation is then further transformed in order to conform with the transport equation for the salt commonly used in dispersion studies, such that one recognizes a dispersion term and a convection term. The dispersion coefficient appears to contain an element due to salt sieving. The convection term appears as the product of the volume flux, the equilibrium salt concentration and a term involving the reflection coefficient.
Immobilization of Diammonium Phosphate and Monocalcium Phosphate in Calcareous Soils
Authors: Amer Fathi , Shams M. S. , Awad K. M. , Khalil M. A. 
Published: July 2010

AbstractImmobilization of monocalcium phosphate (MCP) and diammonium phosphate (DAP) was investigated in an alluvial soil (4.1% CaCO3) and in a desert soil (39% CaCO3). Laboratory experiments were performed to study P solubility in the fertilized soils as affected by wetting and drying cycles and by moisture tension. In addition, the relationship between NH3 volatilization and P solubility was evaluated for DAP, and the agronomic effectiveness of the two fertilizers was tested in a greenhouse experiment. At 4,900 ppm P both fertilizers saturated the alluvial soil during the first 10 cycles with respect to dicalcium phosphate dihydrate (DCPD). The MCP‐treated desert soil was DCPD‐saturated for the first cycle then suffered a sharp decline in soluble P, but maintained DCPD saturation with the addition of organic matter. DAP, on the other hand, failed to saturate the desert soil with DCPD and a negative relationship was obtained between NH3 volatilization and P solubility. In soil columns soluble P increased with depth for DAP while for MCP it was dependent on the moisture tension, the lower the tension the higher the solubility. Greenhouse results were in agreement with the laboratory findings. DAP and MCP were equally effective in the alluvial soil but MCP was superior in the highly calcareous desert soil, especially when combined with organic matter application.
Calculating Cation Exchange in a Salt Transport Model
Authors: Robbins C. W. , Jurinak J. J. , Wagenet R. J. 
Published: July 2010

AbstractA cation exchange subroutine that can be expanded to include any number of cations was developed and interfaced with a water flow‐salt transport model that also contained a lime and gypsum precipitation‐dissolution chemistry subroutine. The exchange subroutine was required by the complete model to satisfactorily predict EC, SAR, and specific ion concentration changes with time and depth for a gypsiferous and a non‐gypsiferous soil irrigated with waters containing three different CaSO4 concentrations at two leaching fractions. In his sudy, exchangeable Ca, Mg, Na, and K were considered. Exchangeable K was included for use with high exchangeable and soluble K soils and high K irrigation waters. The additional cation exchange coefficient values needed for K exchange and a method for their calculation is given.
Measurement of Fertilizer Phosphorus Residues and Its Utilization
Authors: Spratt E. D. , Warder F. G. , Bailey L. D. , Read D. W. L. 
Published: July 2010

AbstractA values and sodium bicarbonate (NaHCO3) extraction soil tests were used to determine phosphorus (P) levels over 8 years on four soils which had been treated with 0, 100, 200, and 400 kg P/ha. The tests correlated highly with each other and indicated the decline of residual fertilizer‐P over years as the soils were cropped. Reliable predictions for the duration of the beneficial effects of large amounts of fertilizer‐P could be made for the two Manitoba soils where cropping was continuous (wheat‐flax) but not for the Saskatchewan soils where fallow was included (wheat‐fallow). By using the linear equation of NaHCO3 soil tests vs. time (years), it was predicted that 100, 200, and 400 kg P/ha would last about 6, 9, and 13 years, respectively, before further fertilizer‐P inputs were needed to maintain wheat production. Longer durations were predicted for 200 and 400 kg P/ha when curvilinear relationships were used, averaging 11 and 22 years, respectively, giving better economic feasibility. These soil testing techniques may be used on calcareous soils to minimize current fertilizer‐P inputs for wheat where residual fertilizer‐P has accumulated.
Liming and Lime‐Phosphorus‐Zinc Interactions in Two Nigerian Ultisols: II. Effects on Maize Root and Shoot Growth
Authors: Friesen D. K. , Miller M. H. , Juo A. S. R. 
Published: July 2010

AbstractTwo greenhouse experiments, the first a complete factorial comprising six rates of lime, four of phosphorus (P) and three of zinc (Zn) on two kaolinitic Ultisols, and the second involving factorial combinations of lime at four levels or gypsum at two chemically equivalent levels with three levels of P on one Ultisol, examined lime‐nutrient interactions in the growth of maize (Zea mays L.) shoots and roots in relation to interactions in nutrient availability in the soil.Strong, highly significant interactions in maize growth were observed on both soils. The lime‐P interaction was positive and occurred only at lime rates less than equivalent to the KCl‐exchangeable Al content. Both total P uptake and root surface area per unit length increased substantially with liming to pH 5.5, but P uptake per unit root surface area was not altered. Total P uptake was linearly correlated with root surface area at each level of applied P and with the product of root surface area and available P, suggesting that the lime‐P interaction was due primarily to the effect of lime on improving root exploitation of available P in the soil.The third‐order lime × P × Zn interaction was observed at high lime rates in the pH range of 6 to 7. Overliming depressed yields only where Zn was not applied; shoot yields were closely related to Zn activities in soil solution. total P uptake was not reduced by liming soils to neutrality but total Zn uptake was linearly correlated with the product of Zn activity (controlled by soil pH) and root weight (influenced by P nutrition).Aluminum toxicity was shown to be the primary growth‐limiting factor for maize grown in the two Ultisols under greenhouse conditions. Plants did not respond to gypsum treatments even though tissue concentrations and gross uptake rates of Ca were raised to levels comparable to equivalent lime treatments. Maize shoot yields were closely related to exchangeable Al saturation and total Al concentration in soil solution and declined at levels in excess of 28% and 4 µg/ml, respectively. Maximum shoot yields occurred at comparatively low rates of lime sufficient to raise soil pH to about 5.0 in the fertilized soils.
Decomposition of Aflatoxin in Soil
Authors: Angle J. S. , Wagner G. H. 
Published: July 2010

AbstractCorn infected by Aspergillus flavus and A. parasiticus is frequently contaminated with aflatoxin. If the contamination exceeds 20 ppb, the corn is considered unfit for animal consumption and is often plowed into the soil. This study was undertaken to determine the fate of aflatoxin in the soil. Aflatoxin B1 was added to soil at a rate of 10,000 ppb. The soil was periodically extracted with acetone, and the quantity and species of aflatoxins were determined using thin‐layer chromatographic procedures. The rate of decomposition was also monitored by adding 14C‐aflatoxin to the soil and periodically measuring the evolution of 14CO2.Aflatoxin B1 was observed to be rapidly reduced to aflatoxin B2 when added to the soil. The speed of this reaction suggests a chemical mechanism. The resulting aflatoxin B2 decomposed at a much slower rate, declining to a level where it could no longer be detected at 77 days. Aflatoxin G2 was also detected 2 days after the addition of aflatoxin B1 to the soil. Its concentration remained, however, well below that of the other aflatoxins observed. Aflatoxin G2 reached a maximum concentration at 14 days after the addition of aflatoxin B1 to the soil and was no longer detectable at 49 days. Microbial decomposition of 14C‐aflatoxin B1, as measured by CO2 evolution, accounted for 14% of added 14C in 112 days of incubation. When wheat straw or sugar was added to the soil, the amount of aflatoxin C liberated as CO2 was less.
Evaluation of Selected Processes Controlling Nitrogen Loss in a Flooded Soil
Authors: Reddy K. R. , Patrick W. H. , Phillips R. E. 
Published: July 2010

AbstractThe roles of NH4‐N diffusion, NH4‐N oxidation, NO3‐N diffusion, and NO3‐N reduction in controlling N loss from continuously flooded soil were evaluated in independent experiments. Applied NH4‐N moved from zones of high NH4‐N concentration to the zones of low NH4‐N concentration. The average diffusion coefficient (D) for NH4‐N in flooded soil ranged from 0.059 to 0.216 cm2 day−1 for different soils. Diffusion coefficients were influenced by soil type and soil‐water content. Rate of NH4‐N oxidation in the aerobic layer of flooded soil range from 1.2 to 3.5 µg g−1 day−1 in different soils. Nitrate diffusion into the anaerobic soil layer ranged from 0.96 to 1.91 cm2 day−1, whereas NO3‐N reduction rates were 0.32 to 0.52 day−1. The slow rate of NH4‐N diffusion from the anaerobic soil layer to the aerobic soil layer and the slow rate of NH4‐N oxidation in the aerobic soil layer indicate that these two processes are limiting steps in controlling N loss. Nitrate diffusion into the anaerobic soil layer and NO3‐N reduction in the anaerobic soil layer were found to proceed at a faster rate and are not likely to limit N loss from flooded soil.
An Aerobic‐Anaerobic Interactive System for Soil Suspensions
Authors: Hunt P. G. , Matheny T. A. , Parsons J. E. , Campbell R. B. 
Published: July 2010

AbstractA system was developed that allows for the simultaneous batch study of aerobic and anaerobic soil suspensions. It is a modification of earlier systems that allowed for the investigation of homogeneous suspensions at desired oxidative‐reduction potentials. This system allows for the contents of aerobic and anaerobic reaction vats to be mixed at desired proportions by using a peristaltic pump connecting the two systems. A desktop computer‐based data acquisition system is used to control the pumping time and to monitor the redox potential in the respective vats. By using the HP 9825 calculator and the HP‐IB bus, one can program the pumping, based on time, Eh readings, or other monitorable parameters. Gas samples taken from the air space of each unit permits one to study biological and chemical processes as they are affected by interaction of components from aerobic and anaerobic suspensions.
Relation Between pHc and Sodium Adsorption Ratio (SAR) and an Alternative Method of Estimating SAR of Soil or Drainage Waters
Authors: Suarez D. L. 
Published: July 2010

AbstractThe relation between the sodium adsorption ratio (SAR) and pHc derived here predicts SAR of the drainage water (SARdw) better than existing empirical equations. Inaccuracies in SAR estimates from the new relationship can be anticipated by the extent to which the derived conditions are valid. Empirical equations provide no understanding of why they are sometimes inaccurate. Due to the relative insensitivity of SAR to calcium concentrations, SAR predictions of most drainage waters (where Ca ≅ ½ HCO3) are satisfactory when the Ca concentration of the drainage water is assumed to be constant at any fixed PCO2. Prediction of SAR in drainage or soil water in the absence of gypsum precipitation requires knowledge of PCO2, irrigation water composition, HCO3/Ca ratio, and the leaching fraction. SARdw can be simply and accurately calculated from the derived equation and a table accounting for ionic strength and HCO3/Ca ratio.
Calcium Phosphate Precipitation: Effects of Common and Foreign Ions on Hydroxyapatite Crystal Growth
Authors: Brown J. L. 
Published: July 2010

AbstractCalcium phosphate precipitation from slightly supersaturated solutions was induced by addition of hydroxyapatite (HAP) seed crystals. The rate of seed crystal growth was measured during the first 60 min by disappearance of P from solution. Effects of solution Ca2+, F‐, initial P, Mg2+, HCO3‐, and HAP seed concentrations on crystal growth were measured by evaluating the empirical reaction order (n) and the rate constant (K) for P‐removal by fitting the data to the equation for interface‐controlled crystal growth. Phosphate disappearance had second‐order dependence on the P concentration when initial F was > 0.05 mM. An increase of either 1 mM Ca or 0.1 mM F caused an increased‐P removal rate of about 10 times. Both Mg and HCO3 interfered with crystal growth. The P‐removal rate was aproximately seven times more rapid at the 1‐mM HCO3 level than at the 6‐mM level. Apatite crystal growth was strongly reduced in the presence of Mg. An increase of 1 mM Mg decreased the P‐removal rate by greater than two orders of magnitude. Reactions exhibited second‐order dependence on the P concentration when interfering ion concentrations were minimal and F was present. Values of (n) increased regularly when increasing concentrations of either Mg or HCO3 were present. Surprisingly, relatively high initial P concentrations caused temporary crystal growth interference although this could also have been due to Mg. Apatite crystal growth was strongly influenced by seed concentrations. An increase of 100 mg/liter HAP resulted in a rate constant increase for P‐removal of more than three orders of magnitude.
Effect of Lime on Exchangeable Magnesium in Variable Surface Charge Soils
Authors: Grove J. H. , Sumner M. E. , Syers J. K. 
Published: July 2010

AbstractEarly work with commercial‐grade limestones containing small quantities of MgCO3 (2–10%) demonstrated that exchangeable Mg was reduced as the soil pH was increased in several soils. An incubation experiment was conducted to more precisely determine the extent of the Mg “fixation” and to evaluate several hypotheses regarding the mechanism behind this pH‐dependent phenomenon.Five acid topsoils were used in this study. The clay fractions of four of these were dominated by constant‐surface potential colloids. Five levels of lime (CaO) and three levels of Mg from two sources (MgCO3 and MgSO4) were applied in complete factorial combination. Exhaustive extraction with 0.2N NH4Cl was used to determine exchangeable Mg and K. Cation exchange capacities were obtained by extracting the NH4+ saturated samples with 0.2N KNO3.The Mg‐fixation reaction was essentially complete in 24 hours. Lime application reduced NH4Cl‐extractable Mg in all soils, although not until the soil pH was raised to 5.1 (1N KCl). Effective CEC increased with lime addition but was unaffected by Mg treatment. It appears that the Mg was lost to a surface‐solid phase involving Al. For the soils with clay fractions dominated by constant‐surface potential colloids, Mg recovery by NH4Cl was inversely related to the quantity of exchangeable Al per unit mass of clay found in the acid‐end member of each soil. The lack of change in effective CEC and exchangeable K with Mg addition at higher soil‐pH values indicated that a charge blocking brucite‐like interlayer was not formed.