bluuebunny/crossref_metadata_2025_split huggingface dataset:
Soil‐heat Flux Determination: Temperature Gradient Method with Computed Thermal Conductivities
Authors: Kimball B. A. , Jackson R. D. , Nakayama F. S. , Idso S. B. , Reginato R. J. 
Published: July 2010

AbstractSurface soil‐heat fluxes were determined for 6 days in a field of Avondale loam using the null‐alignment method, the combination method, and four variations of the temperature gradient method with thermal conductivities computed from the DeVries' theory for particular reference depths. For all methods, calorimetry was used to obtain the surface flux from the flux determined for the reference depth.There was 10% or less difference between the null‐alignment, combination, and temperature gradient methods for a 20‐cm reference depth. However, the difference with respect to the null‐alignment method increased to 35% for a 5‐cm reference depth when DeVries' theory was closely followed. This difference was reduced to 3% when a modified air shape factor was used in the computations and all vapor movement was ignored. We concluded that the temperature gradient method with conductivities computed from DeVries' theory could be reliably used with a 20‐cm reference depth, but that a “calibration” of the theory for a particular soil should be obtained before the method is used with a 5‐cm reference depth.When properly used, the temperature gradient method with computed conductivities has the advantage that reliable estimates of surface soil‐heat flux can be obtained without requiring heat flux plates like the usual combination method nor many computations like the null‐alignment method.
Phosphorus Fertilization with Drip Irrigation
Authors: Rauschkolb R. S. , Rolston D. E. , Miller R. J. , Carlton A. B. , Burau R. G. 
Published: July 2010

AbstractApplication of plant nutrients with drip irrigation systems is desirable for labor and energy savings and flexibility in timing nutrient applications. Evaluations of P movement in the soil and uptake by tomatoes (Lycopersicum esculentum) were made when orthophosphate and glycerophosphate were applied through a drip irrigation system and in comparison with 26 kg of P/ha banded below the seed at planting. A significantly higher P content was measured in seedling leaves when 26 kg of P/ha was applied by drip irrigation than when the same rate was banded. No differences in P content of whole tops of seedlings were measured at equal rates of inorganic or organic P applied through the drip system. There was a significant linear response of P uptake to P rate.With drip irrigation, orthophosphate moved a much greater distance into the soil than had been previously observed for comparable application rates per hectare. Glycerophosphate moved 5 to 10 cm farther through the soil at application rates of 6.5 and 13 kg of P/ha than did orthophosphate. At the relatively high rate of 39 kg of P/ha, orthophosphate moved 25 cm horizontally and 30 cm vertically in the soil profile. Movement of orthophosphate resulted from saturation of the soil reaction sites near the point of application with phosphorus and subsequent mass flow with the soil water. The distance of P movement was proportional to the application rate. Glycerophosphate must undergo enzymatic hydrolysis before releasing orthophosphate ions into the soil solution where orthophosphate can be removed from solution by soil reactions. Consequently, glycerophosphate moved farther than orthophosphate at low application rates.
Properties of Some Tidal Marsh Soils of Florida
Authors: Coultas C. L. , Calhoun F. G. 
Published: July 2010

AbstractPsammaquents, Sulfihemists, and Sulfaquents were found in the tidal marshes of Hernando (Gulf Coast) and Duval (Atlantic Coast) counties, in Florida. They were saline and near neutral in pH and, with the exception of the Psammaquents, contained higher levels of S (2.66–5.19%). Hernando County soils were shallow over limestone and much sandier than those in east Florida. Duval County soil clays were primarily montmorillonite, mica, and kaolinite but Hernando County soil clays were mostly vermiculite‐chlorite intergrade and kaolinite‐metahalloysite. Except for one of the Psammaquents, the soils contained relatively high levels of organic matter (7.8–28.9% organic C) and extractable bases. Juncus roemerianus Scheele is the principal plant in these marshes. The bulk density of the organic soil layers ranged from 0.13 to 0.36 g/cm3, whereas that of the clayey layers was 0.16 to 0.25 g/cm3.
Soil‐Site Productivity for Natural Stands of White Pine in Massachusetts
Authors: Mader Donald L. 
Published: July 2010

AbstractSoil and site characteristics for prediction of white pine (Pinus strobus L.) growth were studied in over 80 stands throughout Massachusetts. Soil descriptions, site characteristics, and stand growth were noted in the field. Samples from the soil horizons were analyzed in the laboratory for physical and chemical properties. Step‐wise multiple regression computer analyses provided growth prediction equations for several levels of complexity of the soil and site data input. Prediction from topographic variables was poor. Addition of soil physical and chemical variables improved the prediction. Of the growth measures, height was predicted most accurately, age plus soil variables accounting for 80–90% of the variation. Soil and site variables accounted for up to about 60% of the variation in site index, and for periodic cubic volume increment up to about 70%. Total board and cubic volume are predicted quite well by age and soil‐site factors (R2 ca 0.6–0.8). Basal area is not predicted well. Textural components, coarse materials, drainage class, organic matter, pH of lower horizons, and moisture characteristics were common significant factors. The equations for site index, total height and cubic volume growth should be useful for prediction of white pine site productivity in Massachusetts.
The Separation Factor Applied to Some Soil Ion Exchange Equilibria
Authors: Kittrick J. A. 
Published: July 2010

AbstractA variety of exchange equations are available to investigators, who may select the one that best fits their purposes or experimental data. Although equations based upon the separation factor (which does not contain ionic valences as exponents) have not been frequently used in ion exchange equilibria in soils, this investigation indicates that the approach may deserve more attention. Some monovalent‐divalent ion exchange equilibria with montmorillonite are closely predicted by the separation factor. Further, variations in the separation factor with soil mineralogy and total solution concentration appear to be small enough to permit useful prediction of the ratio of exchangeable Na+ and Ca2+ in the soil from the ratio of Na+ to Ca2+ in the saturation extract.
Tripolyphosphate and Pyrophosphate Hydrolysis in Sediments
Authors: Blanchar R. W. , Riego D. C. 
Published: July 2010

AbstractThe rate of hydrolysis of tripolyphosphate (TPP) and pyrophosphate (PP) in river, creek, and lake sediments was determined. Half‐lives for the hydrolysis of TPP and PP ranged from 1.6 to 2.6 and 6.7 to 27.4 days, respectively. The influence of temperature, biological activity, and pH on the rate of TPP and PP hydrolysis was investigated using Flat Branch Creek sediment. The rate of TPP and PP hydrolysis increased with increasing temperature. The activation energy was 5,415 cal/mole for TPP and 10,412 cal/mole for PP. TPP and PP hydrolyzed slower in sediment which had been autoclaved than in non‐sterilized sediment. The half‐life for TPP hydrolysis was 1.76 day at pH 5, 1.61 day at pH 7, and 2.16 day at pH 9. The rate of PP hydrolysis was increased as pH increased from 5 to 7 to 9 as indicated by half‐lives of 13.7, 10.0, and 7.3 days, respectively. When TPP was added to the sediment as a Ca5(P3O10)2 precipitate, the rate of hydrolysis was slower than when TPP was added as a solution.
Particle Shape and Sodium Self‐diffusion Coefficient in Mixed Sodium‐calcium Montmorillonite
Authors: Dufey Joseph E. , Banin Amos , Laudelout Henri G. , Chen Yona 
Published: July 2010

AbstractVarious parameters related to the shape of clay particles and self‐diffusion coefficients of sodium were measured in Camp‐Berteau montmorillonite suspensions equilibrated with NaCl‐CaCl2 solutions of 0.01 total normality, and variable ratios of Na to Ca. As the equivalent ionic fraction of exchangeable sodium decreased from 1.0 to 0.0, the anion exclusion volume decreased from 2.9 to 0.5 ml g‐1, the hydration of clay sediment decreased from 8.6 to 4.4 ml g‐1, the average number of plates per tactoid increased from 1.4 to 3.9, and the axial ratio of the clay particles decreased from 190 to 90. At clay content of about 27 g/liter, the self‐diffusion coefficient of Na increased from about 0.40 × 10‐5 to 0.76 × 10‐5 cm2 sec‐1 at 16°C and from 0.55 × 10‐5 to 1.16 × 10‐5 cm2 sec‐1 at 33°C, as the ionic fraction of exchangeable Na decreased from 1.0 to 0.15.The calculated surface diffusion coefficient of sodium was found to be about 30% of its value in the free solution for a pure sodium clay and thereafter increased up to about 50% of that value for a clay loaded by 15% Na. The activation energy involved in the surface diffusion process was calculated to be in the range of 3 to 6 kcal/mole, and a minimum was found for the clay containing about 70% Na. As evaluated from the data on the number of platelets per tactoid the internal surfaces of which were assumed to be preferentially occupied by Ca, this minimum could perhaps correspond to a completely demixed system. A less refined but nevertheless rather satisfactory approach was also attempted for interpreting the variation of the observed self‐diffusion coefficient of Na as a simple result of the change in the distribution of that ion between the surface phase and the free solution.
Control of Zn2+ in the Soil Solution by Sphalerite
Authors: Kittrick J. A. 
Published: July 2010

AbstractZinc (Zn2+) levels in the soil solution are in the parts per billion range. Most known Zn compounds are too soluble to control Zn2+ at such levels. However, ZnS (sphalerite) is a highly insoluble compound in the presence of even traces of H2S. Although H2S is thermodynamically unstable under aerobic conditions, concentrations of H2S actually found in the atmosphere are high enough to engender control of Zn2+ in the soil solution by ZnS in aerated soil samples. In soils, especially under anaerobic conditions, even higher levels of H2S prevail which could depress Zn2+ concentrations to very low levels. Some of the deleterious effects of H2S on plants under anerobic conditions actually may be due to Zn deficiency.
Potassium Sources and Availability in a Deep, Sandy Soil of East Texas
Authors: Hons F. M. , Dixon J. B. , Matocha J. E. 
Published: July 2010

AbstractSoil properties were assessed that may have contributed to the failure of Coastal bermudagrass [Cynodon dactylon (L. Pers.)] to respond to application of K on Darco fine sand for 5 consecutive years. The depth to which plant roots absorbed K was assessed by field observation and by determination of K levels in control and treatment plots. Potassium minerals were determined by chemical methods to assess potential nutrient sources.Potassium removal was indicated to at least 160 cm by soil solution content and to 235 cm by exchangeable K concentration and Gapon selectivity values. Depth of bermudagrass rooting was in agreement with chemical indicators of K removal.Mica and interstratified mica in the fine silt and clay fractions correlated best with exchangeable K (r2 = 0.97) suggesting a direct influence of the finer micaceous materials in Darco soils upon K retained in an exchangeable form and possibly upon K release. Inclusion of feldspar‐K with mica‐K reduced the r2 value from 0.97 to 0.83 suggesting that K‐feldspar does not contribute appreciable K to exchangeable form. Feldspar was present mostly in the sand and two coarser silt fractions which expose little surface area to weathering forces.The large rooting volume of Coastal bermudagrass in Darco soil in conjunction with the mica and appreciable interstratified mica present may explain why no plant response was obtained to K application.
A Technique to Determine Iron Efficiency in Plants
Authors: Brown J. C. , Jones W. E. 
Published: July 2010

AbstractSoil tests should predict crop response to fertilization. In the case of Fe, plant factors seem to affect the use of Fe by the plant; thus, soil tests may not be reliable. Use of soil Fe by plants is genetically controlled by an adaptive mechanism which is activated in Fe‐efficient plants in response to Fe‐stress, but remains inactive if Fe is sufficient. Fe‐inefficient plants develop less Fe‐stress response than Fe‐efficient plants. Using this range of Fe‐stress response in plants as a basis, we developed a technique to screen plants for Fe efficiency.A limited supply of Fe and some control of pH in the growth medium were required in this technique. The pH was controlled by using nutrient solutions, N only as No3, and N as NH4 and NO3, and by varying the CaCO3 and P concentrations in the solutions. The optimum supply of Fe (0.2 mg Fe/liter) was determined by growing the plants at different Fe concentrations.Four Fe‐inefficient and four Fe‐efficient plant varieties, representing four plant species, were used as test plants. The plants were screened in mixed cultures and were rated in order of greatest Fe efficiency as follows:T3238FER tomato (Lycopersicon esculentum Mill.) ≥ Hawkeye soybean (Glycine max (L.) Merr.) > W59 Corn (Zea mays L.) > Pioneer 846 sorghum (Sorghum bicolor (L.) Moench) > PI‐54619‐5‐1 soybean > Wheatland sorghum > ys1/ys1 corn > T3238fer tomato.Green plants contained more and chlorotic plants contained < 43 µg Fe/g, but the degree of Fe‐chlorosis was the best index of Fe‐efficiency. A suggested sequence for screening plants for Fe‐efficiency is presented.
High‐altitude Photography in the Development of a Generalized Soil Map
Authors: Rust R. H. , Finney H. R. , Hanson L. D. , Wright H. E. 
Published: July 2010

AbstractState‐wide panchromatic photography of Minnesota was obtained at a contact scale of 1:90,000 and used for compiling a series of generalized soil maps. The taxonomic legend used was developed from selected concepts in Soil Taxonomy, generally at the subgroup level. The mapping rate is about one township per day with maximum use of stereo‐interpretation. Maps are compiled on composites of the U.S. Geological Survey 1:250,000 quadrangles. A concept of geomorphic regions is used to identify and isolate distinctive parent materials and topography. About 75 such regions are delineated. A concept of soil landscape units (SLU) was developed for mineral soils. These are viewed as collections of soil bodies having broad similarity in particlesize class of the control section and of material below the control section; in position and duration of the water table; and in the presence or absence of a mollic epipedon. For areas of organic soils, a taxonomic legend using suborder concepts was developed.
Particle‐Size Distribution Characterization for the Coarse Fraction of a Granite Soil. I. A model.
Authors: Russell D. A. 
Published: July 2010

AbstractMany central African soils are sandy single‐grain‐structure materials developing under semiarid conditions, and derived from the underlying granite. To obtain a useful size distribution function for the nonclay fraction required a quantitative model for granite disintegration.Methods of characterizing particulate distributions are briefly reviewed with reference to the mechanisms giving rise to them. J. G. Bennett's (1936) description of brittle solid disintegration has been extended to yield the incomplete gamma function as a descriptor of the product of granite disintegration. This is discussed and compared with the log‐normal and Weibull functions in terms of postulated mechanisms.It is concluded that the mechanism presented here more closely approximates the disintegration process than those yielding the above two functions, and that the resulting incomplete gamma function should be a reasonable basic descriptor of the particle‐size distribution of disintegrating granite.
Influence of Row Spacing and Straw Mulch on First Stage Drying
Authors: Adams J. E. , Arkin G. F. , Ritchie J. T. 
Published: July 2010

AbstractEvaporation during first stage drying was measured with evaporation plates on the soil surface in grain sorghum plots with 25‐, 50‐, and 100‐cm row spacings, during several stages of grain sorghum [Sorghum bicolor (L.) Moench] development in 1972 and 1973. Evaporation during first stage drying was affected by row spacing, leaf area index (LAI), and soil shading. Both LAI and soil shading were related to row spacing and plant population. The more complete plant canopy of grain sorghum with narrow‐row spacing decreased penetration of radiant energy to the soil surface and reduced the evaporation rate of soil water during first stage drying. Evaporation was greatest during the early part of the season when shading was least and lowest during boot stage and pollination, when all leaves were fully expanded and provided maximum plant canopy and soil shading. Narrow‐row spacing established an earlier, and more complete plant canopy than conventional 100‐cm row spacing and shaded more of the soil surface from early vegetative growth to maturity. Soil surface shaded near solar noon was a better indicator of first stage evaporation beneath a canopy than LAI.The combined effect of a mulched surface and a plant canopy on reducing evaporation was the product of the fractional reduction in potential evaporation resulting from the plant canopy and the evaporation resulting from the mulched surface with no canopy cover. An empirical equation was developed from the evaporation data for use in calculating first stage evaporation as related to potential evaporation, fraction of the soil surface shaded, and mulch rate.
Sequel to “Residual Availability of Fertilizer Zinc”
Authors: Boawn Louis C. 
Published: July 2010

AbstractA previously reported experiment which evaluated residual availability of fertilizer Zn for 5 years after application was sampled for two additional years. These additional data confirm that fixation of Zn against extraction with DTPA solution reaches an equilibrium and that a new extractable‐Zn level is established for each rate of Zn added.
Percolation of Surface‐applied Water in the Field
Authors: Quisenberry V. L. , Phillips R. E. 
Published: July 2010

AbstractPercolation of surface‐applied water tagged with chloride was studied in Maury silt loam and Huntington silty clay loam under field conditions. Soil samples were taken in small increments to the 90‐cm depth several times following application of water. Analyses of chloride content with depth indicated the position of the applied water relative to the initial soil water in the profile.Three percolation studies were conducted on Maury silt loam soil. In study 1 an application of 4.2 cm of water increased the water content to the 60‐cm depth within 1 hour following irrigation even though the volumetric water profile averaged 5% below the upper limit of the water holding capacity through this depth. A second study conducted at a slightly higher initial water content showed that 20% of a 4.2‐cm application had penetrated below the 90‐cm depth immediately after application and 40% penetrated below this depth within 1 hour.Similar results were measured in Huntington silty clay loam. Simulated rainfall increased the water content significantly to approximately the 15 cm depth in each of three studies. A large percentage of the water passing this depth apparently percolated past the 90‐cm depth with very little adsorption of water and chloride between these depths.Location of chloride in the profile and movement of chloride past the 90‐cm depth indicated that a large percentage of the applied water percolated past the water initially present with little displacement of the initial water.
Influence of Physical and Mineralogical Properties on Swelling of Soils in Yolo County, California
Authors: Schafer William M. , Singer Michael J. 
Published: July 2010

AbstractSurface samples from 16 California soils with a wide range of swelling characteristics were studied. The coefficient of linear extensibility (COLE) of each soil was correlated with other properties. Total clay content was highly correlated with COLE (r2 = 0.868) while the ratio of expandable clay/total clay (partial r2 = 0.454) also significantly affects swelling. The percent of expandable clay is the single variable best correlated with COLE (r2 = 0.907). Models established to predict COLE from other soil properties were selected from the literature and applied to these soils. Results are compared with measured COLE values, and a new model calculating COLE from interlayer expansion of the smectite fraction of soil is proposed.
Laboratory Testing of Water‐repellent Soil Treatments for Water Harvesting
Authors: Fink D. H. 
Published: July 2010

AbstractField testing of repellents for water harvesting is both slow and costly, often hindering the orderly, rapid progression of the technique. Laboratory tests were developed for rapidly evaluating the effectiveness of water‐repellent treatments on soils. The effect of accelerated weathering from ultraviolet radiation, ozone, and freeze‐thaw cycling on the retention of water repellency and on soil stability were studied. The effect on soil stability of prolonged hydration and water erosion was also considered. Using these laboratory tests, numerous soils, organic materials, and treatment techniques can be quickly evaluated so that field testing can be reserved for only the most promising. A small representative laboratory study, reported here to illustrate the technique, showed that two repellents (a petroleum resin dust‐suppressant oil and paraffin wax) when combined made soil generally more resistant to total weathering effects than did either repellent alone. The dust suppressant helped to stabilize the soil against damage by freeze‐thaw cycling, while the was protected it from degradation by ultraviolet radiation. These laboratory results compare favorably with observations from field plots treated with these two repellents.
Surface and Charge Characteristics of Selected Soils in the Tropics
Authors: Gallez A. , Juo A.S.R. , Herbillon A.J. 
Published: July 2010

AbstractSpecific surface area and surface charge characteristics of some Alfisols and Ultisols from Nigeria were studied. Specific surface are measured by ethylene glycole retention was generally 2 to 3 times greater than the specific surface area measured by N2 adsorption for both surface and subsoil samples. Soils derived from basalt had the greatest surface area per gram of clay as measured by both methods.The surface charge‐pH curves of the soils bear the characteristic features of metallic oxides, indicating that surface charge behaviour of the soils studied follows the constant potential model. Values of PZC for Alfisol and Ultisol samples ranged from pH 3.0 to 3.9. Subsoils generally have higher PZC than corresponding surface horizons. Specific adsorption of sulfate resulted in a shift of the PZC to a higher value and an increase in the magnitude of positive charge.Cation and anion retention measurements showed that soils derived from basement complex rocks and sandstones contain negligible amount of positive charge while soils from basalts bear moderate amount of positive charge at their natural pH condition. Evidence also indicated that the Alfisols and Ultisols bear a small amount of permanent negative charge ranging from 1 to 4 meq/100 g.The limitation of using CEC value determined by conventional procedures as a criteria for soil taxonomy is discussed.