bluuebunny/crossref_metadata_2025_split huggingface dataset:
Soil Phosphorus Availability as Measured by Displaced Soil Solutions, Calcium‐Chloride Extracts, Dilute‐Acid Extracts, and Labile Phosphorus
Authors: Soltanpour P. N. , Adams Fred , Bennett A. C. 
Published: July 2010

AbstractFive rates of Ca(OH)2 and four rates of Ca(H2PO4)2 · H2O were added in all combinations to samples of a P‐deficient, low pH, sandy loam soil. The treated soil was subjected to several wetting‐drying‐pulverizing cycles to facilitate equilibration. Soil solutions were subsequently displaced from subsamples and analyzed; other subsamples were extracted for P with 0.01M CaCl2 and dilute acide (0.025N H2SO4 + 0.05N HCl); “labile P” was determined on subsamples from each treatment; a sorghum‐sudangrass hybrid (Sorghum bicolor X S. sudanese) was grown in the greenhouse to measure P availability.Maximum yield of test plants was obtained at about 22 µm of P in the displaced soil solution, 12 µm of P in the CaCl2 extract, 80 ppm P on soil‐weight basis in dilute‐acid extract, and 50 ppm of “labile P” on soil‐weight basis.The P uptake was highly correlated with the logarithm of P concentration in soil solution (r2 = 0.93) and CaCl2 extract (r2 = 0.93), logarithm of “labile P” (r2 = 0.86) and concentration of P in dilute acid extract (r2 = 0.87). All indexes were nearly equal as indicators of P availability.
Nitrogen Transformations During Continuous Leaching
Authors: Starr J. L. , Broadbent F. E. , Nielsen D. R. 
Published: July 2010

AbstractThe simultaneous occurrence of nitrification, denitrification, and N movement was investigated in a soil column during continuous unsaturated leaching. During a continuous application of an NH4Cl solution, analyses were made of the soil solution with soil depth and time for N as NH4+, NO2‐ and NO3‐; and of the soil atmosphere for O2, CO2, N2O, and N2. The use of 15N permitted direct measurement and quantification of nitrification and denitrification, as well as the transport of N in the liquid and gaseous phases.Solutions to the appropriate equations using measured reaction rate coefficients, pore‐water velocities, and diffusion co‐efficients adequately described the steady state NH4+‐N and NO3‐‐N concentration distribution in the soil profile. Equations were also used to stoichiometrically account for the various interacting species in the N transformations.
Physical Properties of Allophane Soils from the West Indies and Japan
Authors: Warkentin B. P. , Maeda T. 
Published: July 2010

AbstractAllophane imparts unusual physical properties to soils. Some of these properties change markedly when the soil is dried. Samples of moist soils were obtained from two different areas. Plasticity and shrinkage were measured, as indicators of other physical properties, on both moist and dried samples. Several chemical measurements commonly used to characterize allophane were also made on the samples. Infrared spectra and amount of rehydration were both related to the measured physical properties. The plasticity characteristics of allophane, high liquid limit, low plasticity index, and decrease of plasticity index on drying, are suggested as a basis for rating amount and nature of allophane in soils.
Rate of Phosphorus Sorption by Five Oklahoma Soils
Authors: Enfield Carl G. 
Published: July 2010

AbstractTwo equations are evaluated in relation to their suitability as rate equations for phosphorus sorption by selected Oklahoma soils. The rate equation which best fits experimental data was ∂S/∂t = aCbSc where S is the sorbed concentration [mass per unit weight of the soils], C is solution concentration [mass per unit weight of the solution], t is time and a, b, and c are constants.
Determination of the Solubility Product of Various Iron Hydroxides and Jarosite by the Chelation Method
Authors: Vlek P. L. G. , Blom Th. J. M. , Beek J. , Lindsay W. L. 
Published: July 2010

AbstractA modification of the EDTA method of determining ion activities in soil developed by Norvell was used to measure the solubility of various ferric hydroxides. The solubility products of jarosite (KFe3(SO4)2(OH)6) and amorphous Fe(OH)3 were also determined on a natural jarosite nodule taken from an acid sulphate soil.For amorphous ferric hydroxide and lepidocrocite, the method gave pK° values of 39.02 ± .35 and 42.48 ± .23, respectively. Hematite and goethite were too inert to yield reproducible solubilities.For a mixture of jarosite and ferric hydroxide, the respective pK° values were 98.56 and 39.93. These values were used to develop an Eh‐pH stability diagram that helps to explain the occurrence of jarosite under acid oxidizing conditions in soils.
Reactions of Ammonium Ortho‐ and Polyphosphate Fertilizers in Soil: I. Mobility of Phosphorus
Authors: Khasawneh F. E. , Sample E. C. , Hashimoto Isao 
Published: July 2010

AbstractThe mobility of P applied as diammonium orthophosphate (DAP), triammonium pyrophosphate (TPP), or ammonium polyphosphate (APP) was studied in columns of Hartsells fine sandy loam. The fertilizer dissolved in soil moisture that moved towards the application site. This water movement was sometimes against a gradient in soil moisture content, but it was along a gradient in the total potential of soil water.The extent of P movement from all three sources was similar, but the distribution patterns were different. The extent of P movement was influenced more by the initial soil moisture content than by the source of P.A higher fraction of the added P was precipitated when the source was TPP or APP than when it was DAP. The ability of the polyphosphates to sequester soil Fe and Al did not prevent the precipitation of these phosphates nor did it make them more mobile than the orthophosphates. It only delayed the precipitation reaction to a degree that depended on the polyphosphate content of the fertilizer material.
Influence of Genetic Variability on Zinc Response in Wheat
Authors: Shukla U. C. , Raj Hans 
Published: July 2010

AbstractInfluence of genetic variability on Zn response in wheat (Triticum sp.) was evaluated in the greenhouse. There was considerable difference among 21 varieties in the time of appearance and intensity of deficiency symptoms, yield depression, and Zn concentration under Zn stress conditions. Without supplemental Zn, dry matter yields of shoot and roots were 8.6 to 33.5% and 9.4 to 36.8% lower, respectively, than at 5 ppm Zn level. Zinc concentration of varieties ranged from 4.2 to 28.3 ppm under zinc deficiency conditions. The differential response among the varieties was found closely linked to their efficiency in Zn utilization from the soil.
Solution to the One‐Dimensional Linear Moisture Flow Equation with Water Extraction
Authors: Warrick A. W. 
Published: July 2010

AbstractThe one‐dimensional, steady‐state moisture flow equation is solved for arbitrary plant water withdrawal functions using the matric flux potential of earlier investigators to obtain a linearized form. A semi‐infinite flow medium and a finite‐depth medium overlying a shallow water table are considered with the surface boundary condition taken as a flux. Tables are presented giving the matric flux potential (from which the pressure head is easily determined) for several withdrawal functions. Numerical examples show the effects of different surface fluxes and rooting depths on the matric flux potential and pressure‐head profiles. The results are particularly relevant for high‐frequency irrigation.
A Postulated Mechanism for Increasing the Efficiency of Organic Soil Conditioners
Authors: Koch J. T. , Kay B. D. , Lange G. L. 
Published: July 2010

AbstractA mechanism whereby organic polymers may be made more effective in maintaining the water stability of soil aggregates is postulated. The proposed mechanism employs coupling agents which chemically bond parts of the organic and inorganic phases of the aggregate together.Various silane coupling agents and other compounds of similar structure were added to soil aggregates. Predictions based on the proposed mechanism were tested by recording the effects of the compounds on aggregate stability as measured by the wet‐sieving technique. Addition of silicon—functional compounds resulted in a marked increase in the water stability of soil aggregates. However, it was not possible to prove conclusively that the organic functionality of NH2(CH2)3Si(OC2H5)3 participated in the postulated mechanism of strength improvement.
Two‐Dimensional Displacement into or from Water‐Filled Ditches
Authors: Miyamoto S. , Warrick A. W. 
Published: July 2010

AbstractPiston‐type displacement of solutes for steady‐state saturated flow into or from water‐filled ditches is analyzed mathematically and by a sand‐tank model. The displacement front into the drains advances much faster near the drains than in the region midway between them. The presence of an impermeable sublayer accentuates this trend. The front bcomes nearly horizontal for a wider surface impermeable spoil bank or if water is ponded away from the drains. Such a spoil bank may be useful for reducing the amount of water required to leach salts or for minimizing the loss of water‐applied fertilizers into drains. The displacement front for water moving from the ditches into a field (such as for salt intrusion from open ditches) advances in an ellipsoidal pattern. The analysis is also useful for predicting the displacement patterns for localized initial solute distributions. Experimental data obtained from a sand‐tank model agree with the predicted fronts.
Effect of Hydrochloric Acid‐Hydrogen Fluoride Pretreatments on Solubilization of Organic Matter by a Cation‐Exchange Resin
Authors: Pietz R. I. , Adams R. S. 
Published: July 2010

AbstractSoil was pretreated with HCl‐HF solutions prior to organic matter solubilization by an iminodiacetic acid type cation‐exchange resin (Chelex 100). As the normality of HCl‐HF solutions increased from 0.05N to 0.5N, the identifiable soil mineral content of the extracted organic matter decreased and the inorganic element content increased. Pretreatments with 0.1N and 0.3N HCl‐0.3N HF solutions resulted in the highest element concentrations in the extracted organic matter, while the 0.5N HCl‐0.5N HF pretreatment resulted in the smallest soil mineral content. Elemental analysis of the ashed organic matter indicated that it had a high affinity for P, Al, Fe, Zn, Cu, and B solubilized by HCl‐HF. Infrared spectra of the extracted material suggested that metal‐organic complexing occurred through electrovalent bonding between ionized carboxyl groups and solubilized inorganic elements and their hydrous oxides. However, analysis of the supernatant from the HCl‐HF pretreatments indicated that most of the solubilized soil elements remained in solution.
Radar Theory Applied to Reconnaissance Soil Surveys
Authors: Morain S. A. , Campbell J. B. 
Published: July 2010

AbstractThis paper describes the use of radar imagery as a base for reconnaissance soil surveys. Attention is focused on the interpretation of tone patterns as resultants of microwave interactions with terrain. The tone appearance of soils and associated landscape features is governed in large part by surface roughness, moisture content, system resolution and viewing angle. These factors are reviewed in both theoretical and applied terms. For cartographic purposes the resolution of existing imaging radar systems appears adequate for reconnaissance surveys. For interpreting soil attributes, however, both resolution and viewing angle are important considerations. Images from arid and humid environments are interpreted as examples of the application of radar theory to reconnaissance mapping. As with photo interpretation, most soil information is obtained by using a combination of radar reflectance theory and landscape inference. Once the theory is understood, however, radar imagery can offer advantages over black and white photography in terms of timeliness and scale of coverage.
Modified Penman Equation to Provide the Upper Boundary Condition in Computing Evaporation from Soil
Authors: Staple W. J. 
Published: July 2010

AbstractPenman's equation for potential evaporation was modified by including in it the relative vapor pressure h of partially dried surface soil. The modified equation was used to predict evaporative flux from drying soil as a boundary condition in the finite difference solution of the flow equation. The method gave satisfactory agreement in a 20‐day test in which evaporation was measured from short columns of soil in a fallowed plot.
Content and Adsorption of Phosphorus in Black Hills Prairie and Forest Soils
Authors: White E. M. , Gartner F. R. , Thompson W. W. 
Published: July 2010

AbstractPrairie areas within forested areas of the western United States have been attributed to the phosphorus content being higher or lower than the adjacent forested soils. Black Hills forest and prairie soils in South Dakota have about the same quantity of total and available P. Langmuir adsorption and desorption isotherms for PO4‐P are not distinctly different for the prairie and forest soils, which suggests the chemical systems are the same in both soils. Thus, prairie areas in the ponderosa pine (Pinus ponderosa, Laws) forest of the Black Hills are not caused by differences in the phosphorus chemistry of the soils.
Effect of Application Rate, Initial Soil Wetness, and Redistribution Time on Salt Displacement by Water
Authors: Ghuman B. S. , Verma S. M. , Prihar S. S. 
Published: July 2010

AbstractCertain concepts regarding the displacement and profile‐spread of surface‐salts with applied water and the leaching efficiency of the latter were experimentally verified using soil columns. Treatments included different amounts and rates of water application and different initial soil water contents. Salt and water profiles were determined by destructive sampling in 2‐cm depth intervals after variable times of redistribution.Salt front coincided with the water front in the initially dry soil and lagged behind it in the initially moist soil. Salt peak immediately after infiltration and after redistribution, for all initial soil water contents, occurred at a depth above which total water storage equalled infiltration. But the salt spread in the profile increased as the initial water content increased.Immediately following infiltration, salt was displaced deeper with slower than with faster rates of water application. But when the application plus redistribution time was matched, the salt showed deeper movement with water added at faster than at slower rates. These results show that slower rates of water application may not increase the leaching efficiency of water under field conditions.
Potassium Status of Some Costa Rican Latosols and Andosols and their Response to Potassium Fertilization Under Greenhouse Conditions
Authors: Martini J. A. , Suárez A. 
Published: July 2010

AbstractExchangeable, nonexchangeable, and structural K were determined in A and B horizons of seven Latosols and seven Andosols. Responses to K fertilization using tomato (Lycopersicum sculentum) as indicator plant under greenhouse conditions were studied. Forms of K were correlated with each other as well as with crop response to native and applied K.Responses to K fertilization, as measured by plant growth and K uptake, were greater for Latosols than for Andosols and greater in B than in A horizons. Larger responses to K for the Latosols, particularly in B horizons, were associated with lower levels of all forms of soil K and higher (Ca + Mg)/K ratios. Conversely, lower responses to K for the Andosols, particularly in A horizons, were associated with higher levels of all forms of soil K and lower (Ca + Mg)/K ratios.
Soil Water Measurement with an Inexpensive Spectrophotometer
Authors: Bowers S. A. , Smith S. J. , Fisher H. D. , Miller G. E. 
Published: July 2010

AbstractA small, portable, battery‐powered, spectrophotometer was developed to measure soil water content rapidly. Soil water contents of 16 soils were related to the absorbance at 1.94 µm by a soil‐methanol extract by the curvilinear equation
urn:x-wiley:03615995:saj2sssaj197503615995003900030014x:equation:saj2sssaj197503615995003900030014x-math-0001
With the exception of Houston Black Clay, one equation could be used for all soils. Determination time for individual samples was approximately 15 min.
Diurnal and Seasonal Soil Water Uptake and Flux within a Bermudagrass Root Zone
Authors: Rice R. C. 
Published: July 2010

AbstractDiurnal water movement within a bermudagrass [Cynodon dactylon (L.) Pers.] root zone and the uptake of water by the roots was studied in a field plot. A fast response tensiometer‐pressure‐transducer system was used to measure the hydraulic heads. The relations of pressure head to water content and to hydraulic conductivity were determined in situ. Diurnal water content and soil water flux profiles were derived by using the established hydraulic properties. The fast response tensiometer system enabled calculation of flux and water content changes over 2‐hour intervals. Diurnal water extraction rates calculated for different depths and times during the growing season yielded evapotranspiration rates that agreed well with rates measured on similar days in previous years using a lysimeter.
A One‐Step Wetting Procedure for Determining Both Water Characteristic and Hydraulic Conductivity of a Soil Core
Authors: Ahuja L. R. 
Published: July 2010

AbstractReasonable simplifications are used to obtain both the suction‐water content and unsaturated hydraulic conductivity relationships from data measured during wetting of a relatively dry soil core through a high‐hydraulic‐resistance porous plate. For soil‐water contents below the bubbling‐pressure value, the two functions are assumed to be of previously known power forms. The resulting similarity is then utilized to obtain these functions from cumulative inflow and wetting‐front position data, using an iterative numerical solution of the ordinary differential equations. Accuracy of the solution is tested on a set of generated data. Tests of the technique as a whole on generated data for one soil and experimental data for another show it to be promising. For water contents above the bubbling‐pressure value, a method is suggested to obtain the two hydrologic properties from cumulative inflow and soil‐water suction at the other end of the core.
A Field Study of Soil Water Depletion Patterns in Presence of Growing Soybean Roots: III. Rooting Characteristics and Root Extraction of Soil Water
Authors: Arya L. M. , Blake G. R. , Farrell D. A. 
Published: July 2010

AbstractRooting characteristics and water extraction patterns in the root zone of a mature soybean (Glycine max L.) crop were determined in the field. Although rooting density for liter samples of soil varied from 0.07 to 5.0 cm/cm3, nearly 60% of the root zone exhibited densities in the 1.0 to 2.0 cm/cm3 range. Densities near the plant row and at depths of 20 to 45 cm in the interrow space tended to be well above average. Elsewhere densities varied in a random manner. Total root length per plant was about 680 m. Mean root diameters ranged from 120 to 500 µm with the 150 to 300 µm range being the most common. Maximum fresh weight concentration was in the 30‐ to 40‐cm zone. The dry root weight monotonically decreased with depth. The ratio of fresh to dry weight increased with depth.Rates of water extraction by the roots in the various 10‐cm intervals were computed over an irrigation‐drying cycle, 81 to 91 days after planting. In the 10‐ to 30‐ and 60‐ to 70‐cm layers the extraction rate decreased with time. In the 30‐ to 60‐cm layer an initial decrease was followed by a substantial increase later in the cycle. Total extraction between 40 and 240 hours after irrigation decreased with depth—1.32 cm in the 10‐ to 20‐cm layers and 0.25 cm in the 60‐ to 70‐cm layers. Extraction rate for the 10‐ to 70‐cm soil during the 47‐ to 56‐ and 81‐ to 91‐days growth periods showed an initially rapid decrease following irrigation but reached constant levels of 0.48 and 0.39 cm/day, respectively.In the light of Philip's (1957) extraction model, our rooting characteristics and water uptake measurements suggest that soil‐water pressure between roots (ΨB) and on root surfaces (ΨR), effective conductivity of the soil (K̄), sink strength (rz), and rooting density (Lv) are related by
urn:x-wiley:03615995:saj2sssaj197503615995003900030023x:equation:saj2sssaj197503615995003900030023x-math-0001Estimates of were negligibly small suggesting that rhizosphere resistance was not a significant factor in our experiments.Patterns of water movement in the two‐dimensional root zone space show considerable deviation of flow direction from the vertical. These deviations suggest that with row crops more sophisticated analyses and more detailed soil and root measurements will be needed for the meaningful interpretation of field data.
Mathematical Analysis of Steady Saturated Flow through a Multilayered Soil with a Sloping Surface
Authors: Selim H. M. , Selim M. Sami , Kirkham Don 
Published: July 2010

AbstractAn analytical solution is presented for a two‐dimensional multilayered hillside seepage problem. The soil is horizontally stratified with each layer having a different permeability. The flow medium is assumed to be water‐saturated to the soil surface, bounded below by an impermeable barrier at a finite depth, and bounded laterally by vertical streamlines. Seepage occurs into the flow medium along the upper part and out along the lower part of the sloping soil surface. Two situations are analyzed, one with a constant slope soil surface and another with an abritrarily shaped soil surface. The potential and stream functions for the problem are developed by starting with a general series solution to Laplace's equation and using a modified Gram‐Schmidt method to determine the series coefficients. Solutions are derived for two‐layered and three‐layered soils. From these derivations, solutions for soils with more than three layers can be readily deduced. The results presented include flow nets, seepage velocities and infiltration rates for two‐layered and three‐layered soils.
In Situ Hydraulic Conductivity at Four Hillslope Locations in a Closed Drainage System
Authors: Matzdorf K. D. , Cassel D. K. , Worcester B. K. , Malo D. D. 
Published: July 2010

AbstractVirtually no information has been published concerning the hydraulic properties of large acreages of till plain soils associated with “Potholes” in Northcentral United States and Canada. The objectives of this research were to measure and compare in situ hydraulic conductivities and selected soil physical properties at several depths in four soil profiles on a till plain in southeastern North Dakota. In addition, theoretical hydraulic conductivity values were calculated and compared with the in situ conductivities.Unsaturated soil hydraulic conductivity vs. depth was measured in situ at four sites on a toposequence developed from a glacial till. Water was allowed to infiltrate the soil at each site and the soil surface covered to prevent evaporation. During the ensuing drainage periods soil water pressure was monitored with triplicate tensiometers at each of six depths. These depths were not arbitrary as in previously reported studies but were selected on the basis of soil morphology. Soil water characteristics, determined on triplicate 7.6‐ by 7.6‐cm cores taken from the same depth as the tensiometer cups, were used in conjunction with the soil water pressure data to compute hydraulic conductivities. Hydraulic conductivity generally increased with depth to about 90 cm. Below this depth, hydraulic conductivity tended to decrease. In addition, hydraulic conductivity values at each depth for each site were computed by the Green and Corey Method. When the matching factor was selected from the midpoint of the measured hydraulic conductivity range, the conductivities computed by Green and Corey's method compared favorably with those measured in situ.