bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Measurement of the Hydraulic Conductivity of Unsaturated Porous Materials Utilizing a Zone of Entrapped Air
Authors: Watson K. K. 
Published: July 2010

AbstractA steady‐state method for determining the major portion of the hydraulic conductivity‐water content relationship of reasonably coarse‐grained unsaturated porous materials is presented. In the method, an initially saturated column of the material, in the process of draining to a water table at its base, is rewet at an appropriate time at its upper surface from a ponded supply. This occasions an increase in the pore air pressure in the zone of air entrapped in the profile between the wetting and draining fronts. Two physical consequences of this flow system, the formation of a bell‐shaped water content profile and the rapid attainment of steady‐state conditions, allow the determination of the conductivity‐water content relationship. Precautions to be taken in using the method are outlined, and experimental details are discussed. Two sets of experimental results are documented.
Soil Water Diffusivity from Horizontal Infiltration
Authors: Whisler F. D. , Klute A. , Peters D. B. 
Published: July 2010

AbstractA method has been developed for the measurement of soil water diffusivity. The method is based on gamma ray absorption measurements of the water content as a function of time at a fixed position in a horizontal infiltration system. The calculation of diffusivity is based on the assumption that the water content is a function of position divided by the square root of time. The variability of the data led to scatter in the diffusivity function especially at high water contents. This variability in the data can be traced mainly to the inability to obtain sufficiently accurate data from the recordings of the gamma ray counting system. When the diffusivity function thus obtained was used to predict the water content time relationship in the column, even though the function had been fit statistically, the results were largely dependent upon the wet end of the relationship.
Flocculation of Clays and Soils by Organic Compounds
Authors: Chang C. W. , Anderson J. U. 
Published: July 2010

AbstractThe effectiveness of 15 substituted benzene ring compounds in flocculating < 2µ Gila clay was evaluated by measuring flocculation percentage and by observation after reaction in water suspension. In general the flocculation percentages were in the order: calcareous clays > noncalcareous, calcium‐saturated clays > noncalcareous sodium‐saturated clays. Effectiveness of organic compounds on carbonate containing clays increases sharply as the pH value drops to about 6.0. In carbonate‐free systems the effect of decreasing pH is not evident until the pH drops to < 4, and is not consistent. Calcium appears necessary for flocculation in all sodium, calcium‐clay systems studied. Interlayer absorption does not insure flocculation, and naturally existing organic matter did not increase flocculation by the organic compounds tested. The effectiveness of the compounds used appeared to depend on the number of active groups, and on the number of unshared electrons. Reactive groups of benzene ring compounds were more effective in the meta than in the ortho or para positions.
Cationic Diffusion in Clay Minerals: I. Homogeneous and Heterogeneous Systems
Authors: Lai T. M. , Mortland M. M. 
Published: July 2010

AbstractModels of homogeneous and heterogeneous cationic diffusion systems were applied to clay minerals. The diffusion of Na and Cs ions in expanded Na‐vermiculite, which has both internal and external surface available for cationic diffusion, decreased with increasing diffusion time, a characteristic of heterogeneous systems. Diffusion of those ions remained essentially constant in collapsed K‐vermiculite which has only external surface available for diffusion and can thus be described as homogeneous. The property of homogeneity was further confirmed with cationic diffusion in the vermiculite whose exchange sites were clogged by p‐phenylenediamine cation, and in Na‐ and K‐kaolinite; while the heterogeneous property was observed for Na‐ and K‐bentonite. The diffusion of Na ion in Na‐vermiculite was related to a model originally derived for mathematical analysis of grain boundary problems. The evaluation of diffusion coefficients of external surface (De) and of interlayer surface (Di) was made, and De of Na ion in Na‐vermiculite was found to be about 5 times larger than that of Di. The importance of considering the homo‐ and heterogeneity of the system in the study of cationic diffusion in clay minerals is suggested.
Further Evidence for a P‐Zn Imbalance in Plants
Authors: Boawn Louis C. , Brown J. C. 
Published: July 2010

AbstractBeans (Phaseolus vulgarus) and potatoes (Solanum tuberosum) were grown using a split‐medium technique that permitted Zn to be supplied to the plants from a soil medium while variable levels of P were supplied from a solution. A balance between P and Zn levels was attained through trial and error so that only the highest level of P induced interveinal chlorosis and stunting.In both crops, P induced the deficiency without causing a decrease in the Zn nutritional status of the plants. Increasing the soil Zn level at a given P level resulted in plants with normal growth. The results are interpreted to support the hypothesis that normal metabolism is dependent upon a physiological balance between P and Zn.
Soil Trends and Variability Across Selected Landscapes in Iowa
Authors: Walker P. H. , Hall G. F. , Protz R. 
Published: July 2010

AbstractSoil profile features such as A horizon thickness, depth to subsoil mottles, depth to carbonates, and surface and subsoil pH were measured in sample grids on small loess and drift landscape segments. Trend analyses were made across the full range of topography, then soil variation was examined within topographic subareas that approximated detailed soil survey delineations. Comparison of standard errors and standard deviations showed that some increase in the precision of predictions was obtained for loess soils when using “trend” rather than “within delineation” analysis. The reverse was true for drift soils. The representation of data in polynomial trend equations is justified because of systematic variation observed across small landscape segments, and from a consideration of a soil landscape model that is generally applicable in Iowa. Using this model, maxima and minima of soil properties are expected along transects from upland to lower pediment slopes. Polynomials provide a statistical fit of soil landscape data and a suitable representation of maxima and minima of soil properties.
An Improved Method for Extracting Organic Matter from Soil
Authors: Gascho G. J. , Stevenson F. J. 
Published: July 2010

AbstractA procedure is described which reduces the possibility of chemical alteration of soil organic matter during extraction, and which permits recovery of most of the solubilized organic matter as an acid‐insoluble material low in ash. The essential features of the method are: (i) destruction of hydrated silicate minerals by pretreatment of the soil with 0.3N HF, (ii) recovery of organic matter by extraction first with 0.02M Na4P2O7 and then with 0.03N NaOH, and (iii) removal of inorganic contaminants by dialysis against 0.3N HF.
A Vacuum System for Accumulating Runoff from Infiltrometers
Authors: Dixon R. M. , Peterson A. E. 
Published: July 2010

AbstractA vacuum system for picking up and accumulating runoff from sprinkler and overland‐flow infiltrometers is described. This system is much simpler than the runoff recirculation system of the Purdue sprinkler infiltrometer. Costs of fabrication, operation, and maintenance are greatly reduced and inherent errors of a malfunctioning recirculation system are avoided. Sampling for subsequent runoff‐quality determinations is facilitated by the vacuum system since no sedimentation occurs in the collection and transfer parts of the system.
Simultaneous Flow of Water and Heat under Periodic Heat Fluctuations
Authors: Hadas A. 
Published: July 2010

AbstractTheoretical Predictions of thermally induced moisture transfer have been compared ot measured quantities. Soil samples at different initial moisture contents were subjected to sinusoidal heat waves having an amplitude of 6C, and various periods of time. Temperatures were measured at various distances from the heat source, using copper‐constantan thermocouples and recording the emf output.The mositure distribution after the 1st, 2nd, 6th, and 16th cycle was determined gravimetrically.The measured net transfer quantities were found to be larger than the theoretically predicted values by factors ranging from 0.8 to 8.0. The discrepancy between predicted and measured values of ent transfer may be attributed to the incompleteness of the theoretical models.
Hydraulic Properties of a Clay Loam Soil and the Field Measurement of Water Uptake by Roots: II. The Water Balance of the Root Zone
Authors: van Bavel C. H. M. , Brust K. J. , Stirk G. B. 
Published: July 2010

AbstractSoil water depletion rates in a 115‐cm and a 170‐cm deep profile of Adelanto clay loam were compared with lysimetrically obtained consumptive use rates for periods of many days after measured water applications. When the soil was bare, the depletion rates were always higher than the rate of loss to the atmosphere, and the inferred flux at the 170‐cm depth was as high as 2 mm/day 8 days after irrigation. When the test plot was planted to sorghum (Sorghum vulgare Pers.) an initially strong downward flux at the 170‐cm depth reversed itself after about 10 days and became as high as 4 mm/day, representing upward flow of water from wet soil into the root zone above. The data imply that indiscriminate use of soil water depletion rates as representing consumptive use rates can be highly misleading at any time in an irrigation cycle. Further analysis shows that a rational and satisfactory correction of depletion data is not likely feasible, and, at any rate, unworkable for the condition of the experiment.
Mathematical Simulation of Water Movement through Unsaturated Nonhomogeneous Soils
Authors: Wang Flora Chu , Lakshminarayana V. 
Published: July 2010

AbstractThe general states of flow of water through unsaturated nonhomogeneous soils have been simulated by the nonlinear diffusion equation. A numerical technique is developed and programed for the IBM 7094 to solve the explicit‐implicit difference scheme analogue of the nonlinear partial differential equation of parabolic‐type.The data utilized in this study for the simulated soil profile are obtained from the experimental work of Nielsen et al. (1964) for vertical drainage and infiltration. Computed cumulative loss and average rate are in reasonable agreement with their field measurements. The results indicate that the average rate of drying and wetting are controlled largely by the physical properties of the soil and their corresponding boundary conditions.
Effect of K+‐Uptake by K+‐Depleted Micas on the Basal Spacing
Authors: Weed S. B. , Leonard R. A. 
Published: July 2010

AbstractPotassium was introduced into expanded, i.e., K+‐depleted, micas by (i) adding about 0.5 symmetry of KCl to a chromatographic column of expanded mica plus sand and (ii) by equilibrating suspensions of Ca2+ or Mg2+‐saturated expanded mica with 0.5, 1.0, 1.5, or 2.0 symmetry of KCl. Two expanded biotites readily formed a regular alternation of 10 and 14A spacings whereas two muscovites did not develop such a phase. A phologopite yielded this phase only at the lowest concentration of K+ tested. Regular alternation developed most readily in the Ca2+‐saturated minerals. Development of regular interstratification did not appear to be related to the gross surface‐charge‐density of the minerals, but did seem to be positively related to the content of octahedral Fe.
Retention of Boron by Layer Silicates, Sesquioxides, and Soil Materials: III. Iron‐ and Aluminum‐Coated Layer Silicates and Soil Materials
Authors: Sims J. R. , Bingham F. T. 
Published: July 2010

AbstractBoron retention as a function of pH was determined for Fe‐ and Al‐coated layer silicates using a previously described procedure (15). Treating the Na+ and K+ forms of South Africa vermiculite material with Al3+ prior to B treatment resulted in equivalent B retention by the two forms. Coating kaolinite with hydroxy iron compounds initially decreased B retention in comparison to uncoated kaolinite. However, as the amount of coating was increased to 4.2% Fe2O3 the amount of B retained was slightly greater than that retained by uncoated kaolinite. Boron retention by the Al‐coated kaolinite and by both Fe‐ and Al‐coated montmorillonite was significantly greater than B retention by the uncoated clays. A single regression line represented B retention as a function of Fe2O3 content for both clays. Boron retention as a function of Al2O3 content for the two coated clays fell on two lines which led to the conclusion that hydroxy Fe and Al compounds in the layer silicates dominate over clay mineral species per se in determining B retention characteristics and that B retention characteristics may be conditioned by clay mineral species.Boron retention at pH 6 by nine soil materials was determined from the difference in the initial and final B concentrations of the saturating solutions. Relationships between B retention and various chemical properties of the soil materials were examined statistically. The highest correlations with B retention were found with free iron oxide content and 1.0N KCl (pH2) extractable Al2O3. It was concluded that B retention by these soil materials was in response mainly to their free iron oxide and Al2O3 contents.
Use of the Stanford‐DeMent Bioassay to Study Atrazine‐Soil Reactions
Authors: Tompkins G. A. , McIntosh T. H. , Dunigan E. P. 
Published: July 2010

AbstractQuantitative detection of atrazine in soil was accomplished using a modified Stanford‐DeMent type bioassay. The technique should be easily adaptable for analysis of other herbicides in soil. The uptake of atrazine by oat plants (Avena sativa, var. Swedish Victory) was directly proportional to the amount of atrazine applied to the soil and inversely proportional to the clay and soil organic matter content. Using 14C labeled atrazine it was found that only a very small amount of atrazine was removed from the soil by one oat crop. The bioassay was used to examine the adsorptive effects of certain model compounds which represented different fractions of soil organic matter. One percent activated charcoal in sand completely inactivated atrazine applied in the range 1.0 to 11.3 ppm. One percent lignin in sand was moderately effective in reducing atrazine phytotoxicity in oats. One percent cellulose in sand was relatively ineffective in adsorbing atrazine. The Stanford‐DeMent type bioassay should be a useful tool for a study of chemical or microbial transformation of herbicides in soil.
Micromovement Mechanisms of s‐Triazines in Soil
Authors: Lavy T. L. 
Published: July 2010

AbstractIn situ autoradiography of corn (Zea mays L., var. WF9 × Hy) roots grown in bands of three different soils treated with 14C ring‐labeled s‐triazines showed that both mass flow and diffusion of the herbicides occur. Mass flow was the most important means of moving the herbicide to the absorbing root in the case of 2‐chloro‐4‐ethylamino‐6‐isopropylamino‐s‐triazine (atrazine) the most water soluble of the herbicides studied. Movement of the soil‐applied herbicides to the corn roots did not insure uptake of the chemical. Mass flow patterns were clearly present around roots growing in the band of 2‐chloro‐4, 6‐isopropylamino‐s‐triazine (propazine) treated Sharpsburg silty clay loam soil; however, the least amount of 14C uptake occurred on this soil‐herbicide combination indicating restrictive herbicide uptake by the plant root.Adsorption of the s‐triazines on the three soils increased as the soil acidity, organic matter, and clay content increased. Plant uptake of 14C decreased as the soil acidity, organic matter, and clay content increased.
Availability of Exchangeable and Nonexchangeable Mg in Sandy Coastal Plain Soils
Authors: Rice H. B. , Kamprath E. J. 
Published: July 2010

AbstractThe chemical forms of Mg in five sandy Coastal Plain soils were determined. The total Mg ranged from 0.73 meq. to 2.48 meq/100g. The percentage of the total Mg in the exchangeable form varied from 3.8 to 9.4% and generally increased as the total increased. Soils containing an expansible lattice clay had the highest Mg content per gram of clay.Consecutive extractions with 1N NaOAc solution of pH 1 removed almost twice as much Mg as consecutive extractions with a solution of 1N NaOAc pH 7. This indicates that a portion of the nonexchangeable Mg is quite soluble in a dilute acid. The soils which released the highest amount of nonexchangeable Mg per gram of clay also were the ones containing some expansible clay minerals.The exchangeable Mg in the range 0.05 to 0.23 meq/100 g of soil appeared to be equally available as indicated by plant uptake. In four of the soils a large part of the Mg taken up by corn (Zea mays L.) came from the nonexchangeable form.
Adsorption of Calcium and Strontium by Crandallite
Authors: Kunishi H. M. , Taylor A. W. 
Published: July 2010

AbstractSamples of the phosphate mineral crandallite, CaAl3(PO4)2 (OH)5 · H2O were equilibrated with solutions containing calcium and strontium chlorides labelled with 45Ca and 85Sr. The apparent selectivity coefficient for the equilibrium system, calculated from the isotopic dilution, varied from 1.5 at pH 9.3 to 8.2 at pH 4.7. The mineral has limited value as a scavenging agent for the removal of strontium from soil.
Movement of Water Tagged With 2H, 3H, and 18O Through Acidic Kaolinitic Soil
Authors: Corey John C. , Horton J. H. 
Published: July 2010

AbstractMiscible displacement techniques were used to compare the behavior of deuterium, tritium, and oxygen‐18 as water tracers. Displacement of a 170‐ml portion of triply tagged water through a 186‐cm‐long column of water‐saturated acidic kaolinitic soil by distilled water revealed no differences in the relative rates of movement of deuterium‐, tritium‐, and oxygen‐18‐tagged water.
Extraction of Cations from Silicate Minerals During the Determination of Exchangeable Cations in Soils
Authors: Rhoades J. D. , Krueger D. B. 
Published: July 2010

AbstractThe extent to which silicate minerals release Ca, Mg, Na, and K during the determination of exchangeable cations in soils by the ammonium‐acetate‐extraction procedure was evaluated. The method of exchangeable‐sodium evaluation used by the US Salinity Laboratory was employed for this study with the exception that soil samples were replaced with reference mineral samples. Amounts of cations equivalent to 0.3 to 21.8 meq/100 g were extracted from the minerals by ammonium acetate. In general, the proportions of cations extracted decreased in the order Ca + Mg>> Na> K. Because of this phenomenon, complications are expected to occur in the evaluation of exchangeable Ca and Mg in arid‐land soils, but not for exchangeable Na except under unusual circumstances. The latter circumstances are described and the general extent of error that may occur is estimated.
Reaction Products of Applied Phosphate in Limed Soils
Authors: Murrmann Richard P. , Peech Michael 
Published: July 2010

AbstractA study was made of the solubility of phosphate in limed soils to which liberal amounts of superphosphate had been added over a long period of time but to which no phosphate had been applied for at least 5 years prior to sampling. The control limed soils to which no phosphate had been applied were also included for comparison. A 20‐g sample of soil was extracted with 200 ml of 0.01M CaCl2 for 108 hours and the concentration of phosphate and pH were determined in the clear supernatant solution after centrifugation. Although the extracts of all soils were found to be undersaturated with respect to hydroxyapatite, most of the extracts were found to be supersaturated with respect to fluorapatite in the presence of solid phase CaF2. By assuming the formation of an ideal solid solution with fluorapatite and hydroxyapatite as end‐members, it was shown that fluorapatite should be the stable phase even in the absence of solid phase CaF2 provided that the F‐ concentration in the soil solution is > 10‐8 M. Consistent with this deducation, the solubility of phosphate in many of the limed soils examined in this study agreed well with that expected for fluorapatite in the presence of 10‐5M F‐ solution, which was the concentration of F‐ found in several of the extracts that were examined. It may be concluded, therefore, that fluorapatite was the ultimate reaction product of the applied superphosphate in these limed soils.
Anaerobic Conversion of DDT to DDD and Aerobic Stability of DDT in Soil
Authors: Guenzi W. D. , Beard W. E. 
Published: July 2010

Abstract14C‐DDT and carrier DDT were added to nonamended and to 1% alfalfa‐amended Pawnee silt loam. One set of sterile and nonsterile soil samples was incubated anaerobically, and another set was incubated aerobically. After predetermined periods of incubation, the soil samples were extracted, the extracts chromatographed on thin layer plates, and the separated radioactive DDT and decomposition products transferred into vials for quantitative determination by liquid scintillation counting.DDT was converted to DDD (TDE) in an anaerobic soil system by microorganisms; only traces of six other degradation products were detected. Amending the soil with 1% alfalfa increased the rate of conversion, and less than 1% of the applied DDT was recovered in the soil extract as the original molecule after 12 weeks of incubation.After six months of aerobic incubation, 75% of the added DDT was recovered in both the sterile and nonsterile soils. A maximum of 4% DDE and a trace of DDD was detected during the incubation period. Less than 1% of the carbon‐14 in the phenyl ring of DDT was oxidized to CO2 in the nonsterile soil. No radioactivity was found in n‐hexane traps, indicating no loss of DDT in the vapor phase.
Effect of Controlled Air and Soil Temperature and Starter Fertilizer on Growth and Nutrient Composition of Corn (Zea mays L.)
Authors: Ketcheson J. W. 
Published: July 2010

AbstractGrain corn (Zea mays L.) yielded higher when grown to maturity under a 22‐12C controlled air‐21C controlled soil temperature combination than when grown under other factorial combinations with 26‐16C air and 17C soil. Lowering air temperatures lengthened the time, whereas increasing soil temperature shortened the time to reach maturity, indicating that growth rates stimulated by air temperature can reduce yields, but growth rates stimulated by soil temperature can increase yields. Starter fertilizer effects on yield were greatest with the temperature conditions giving lowest yield (higher air temperature‐lower soil temperature). Yields correlated negatively with tissue NPK concentration at maturity. Variations in leaf area corresponded to variations in yield.