bluuebunny/crossref_metadata_2025 huggingface dataset:
Relative Flow Rates of Salt and Water in Soil
Authors: Krupp H. K. , Biggar J. W. , Nielsen D. R.
Published: July 2010

A hydrodynamic equation for the mixing of two miscible solutions in a porous media has been combined with the Gouy theory for ion distribution in soil pores in order to examine the effect of flow velocity and ion distribution in the pores on the breakthrough curves. The model considers zones of mobile and immobile solution in the porous media, and the extent these zones are affected by the total concentration of the solution and the pore water velocity.

Miscible displacement experiments of 36Cl and 3H through Panoche clay loam at 0.1, 0.01, and 0.001N total salt concentration using CaCl2 were performed on the same column at a fast and slow flow velocity. It was shown that the exclusion volume for isotope and the separation volume for 36Cl and 3H increased as flow velocity decreased and these changes were related to the total ion concentration, the thickness of the diffuse double layer, and the zones of mobile and immobile solution.
Properties of Five Tropepts in a Toposequence of the Humid Tropics in Costa Rica
Authors: Martini J. A. , Mosquera L.
Published: July 2010

Five Tropepts, in a toposequence developed under a warm humid climate, without a well‐defined dry season, were studied. The parent material varied from limestone in the pediment and upland soils to alluvium and colluvium derived from limestone and andesite in the terrace soils. Some andesitic volcanic ash contamination may have occurred from an adjacent volcano. The objective of this work was to characterize some of the physical and chemical properties, and to relate them to soil genesis, morphology, and performance in the greenhouse using tomato (Lycopersicon esculentum Mill.) as indicator plant. The occurrence of Tropepts and particularly Eutropepts under such climatic conditions was explained by the continuous rejuvenation of the soil parent material through alluviation, colluviation, landslides, and other forms of erosion. The calcareous parent material and possibly some contamination with volcanic ash may also have been a factor. These Tropepts had moderately thin sola, increasing in thickness at higher elevation in the toposequence. They have ochric epipedons and cambic horizons. Weathering, leaching, and profile development became stronger up‐slope where rejuvenation was not too drastic, as in the soils on the pediment backslope. Variations among profiles in this sequence were accounted for by changes in topography and parent material.
Colorimetric, Semiquantitative Test for Soil Salinity
Authors: Bower C. A.
Published: July 2010

A colorimetric, semiquantitative test for soil salinity is described based on the equivalent release of yellow CrO4 ion upon reaction of Cl and SO4 with slightly soluble Ag2CrO4 and SrCrO4, respectively, to form less soluble AgCl and SrSO4.
Gaseous Losses of Nitrogen from Freshly Wetted Desert Soils
Authors: Macgregor A. N.
Published: July 2010

On the basis of manometric data and mass spectrometer analyses, N2 and N2O were formed when samples from the dry surface of two semiarid soils were moistened and incubated under argon for 22 to 42 hours at 38C.

Of the endogenous soil nitrate‐N present in each soil, approximately 60% was volatilized by Pima clay loam (agriculture soil) and 0.6% was volatilized by Sonoita sandy loam (virgin desert soil). When either soil was amended with organic carbon, more gaseous nitrogen (N2 and N2O) was evolved than could be accounted for in terms of the initial level of endogenous nitrate.

In 15N‐experiments, N2O was derived primarily from nitrate. However, although significant amounts of N2O were evolved by both soils, much of the N2O was unlabelled further suggesting nonnitrate sources play a role in volatilization of nitrogen from the soils under study.
An Infrared and Chemical Investigation of the Acid Tin Chloride Method of Determining Quinones in Humus
Authors: Mathur Sukhdev P.
Published: July 2010

Observations of infrared spectral changes accompanying an acid SnCl2 treatment of soil humic preparations and a known quinone confirmed the effectiveness of SnCl2‐HCl for reducing quinones. The treatment did not reduce the nonquinoid but conjugated carbonyls of p‐hydroxy‐benzaldehyde, benzophenone, o‐benzoylbenzoic acid, chalcone, and curcumin. Recent criticisms of the technique were examined. It was proposed that due to the diversity in carbonyl frequencies, the variety of quinone groups and their derivatives, perhaps no single species of quinoid carbonyl was present in amounts adequate enough to be represented by a distinct peak in the spectra of unmodified humic compounds. Instead, there may have been several small peaks, all masked by the broad absorption bands due to other chromophores in the 1600‐ and 1700‐cm‐1 regions. Spectra of blends of fulvic acids (FA) with certain quinones, and naphtharesorcinol, supported the above concept. The 1600‐cm‐1 region of the FA spectra may have represented aromatic −C = C as well as quinones H‐bonded to ‐OH groups. In an indirect manner, this study furnished additional evidence for the presence of quinones in soil humus.
Field Calibration of Soil Tests for Available Zinc
Authors: Alley M. M. , Martens D. C. , Schnappinger M. G. , Hawkins G. W.
Published: July 2010

Laboratory tests were calibrated for detection of soils supplying inadequate Zn for normal growth of corn plants (Zea mays L.). The available Zn tests under investigation were based on amounts of Zn extracted by 0.1 N HCl, dilute HCl‐H2SO4, ethylenediaminetetraacetic acid (EDTA), and diethylenetriaminepentaacetic acid (DTPA). The EDTA procedure gave the best separation of soils supplying either adequate or inadequate Zn for corn plants grown in the field. The “critical” level of EDTA‐extractable Zn for the 10 soils under study was approximately 0.8 ppm. Soils also were separated into Zn deficient and Zn sufficient categories by a three variable equation, Ŷ = 780.2 + 68.8X1 − 101.3X2 − 0.4X3; where Ŷ = Zn availability index, X1 = ppm dilute HCl‐H2SO4 extractable Zn, X2 = soil pH, and X3 = ppm dilute HCl‐H2SO4 extractable P. A Zn availability index of 135 gave the separation.
Response of Corn to Time and Rate of Phosphorus and Zine Application
Authors: Keefer R. F. , Singh R. N. , Horvath D. J. , Henderlong P. R.
Published: July 2010

Corn (Zea mays L.) was grown in the greenhouse on two soils—Monongahela, a Typic Fragiudult (I) and Wharton, an Aquic Hapludult (II), which differed in available Zn, available P, exchangeable Mg, total Zn, and organic matter (OM). Dry matter yield and Zn concentration and content of plant parts were increased where Zn either as ZnSO4 or ZnEDTA was applied with P regardless of time to soil I (low in available Zn, total Zn, exchangeable Mg and OM). Zinc‐EDTA seemed to be a better source of Zn since it increased Zn concentration in leaves and stems more than ZnSO4 on soil I. However, with soil II (higher in available Zn, exchangeable Mg, and OM), response to ZnSO4 application was obtained only when P was applied at high rates 8 weeks before planting. Application of ZnEDTA produced no significant response by corn on soil II, probably due to instability of ZnEDTA under acid conditions resulting in appreciable amounts being fixed on the clays in this soil. The relative response to Zn with increasing levels of P (0 to 200 mg P/kg soil) was greater on soil I than on the soil II. Addition of Zn in the former decreased the percent P and P content in both leaves and stems at high levels of P application; however, application of Zn to the latter did not show any noticeable affect on percent P at all levels of P application.
Measurements of the Standard Entropy of Formation of Clay Minerals
Authors: Santillan‐Medrano Javier M. , Bohn Hinrich L.
Published: July 2010

The standard entropies of several clays were determined by calorimetry. The entropies of kaolinite and halloysite, 0.197 and 0.185 cal/g (50.8 and 47.7 cal/mole), respectively, compared well to literature values. The entropies of 2:1 layer‐lattice aluminosilicate clay minerals were within the range of 0.15 to 0.16 cal/g. The results for the 2:1 clays are considered questionable because of the problem of low thermal conductivity of these minerals. Problems of calorimetric measurements of clay minerals are discussed.
Some Observations on Soils‐Microclimate Interactions
Authors: Southard A. R. , Dirmhirn Inge
Published: July 2010

This paper reports data collected to relate some soil‐micro‐climate interactions. The environmental parameters examined were solar and scattered radiation evapotranspiration, calcium carbonate equivalent, organic matter, and particle size distribution. The data show a strong interaction between slope aspect or direction of exposure and soil properties. The need for careful observation of soil properties below the soil surface in selecting research sites is apparent.
Calcium, Magnesium, and Potassium Saturation Ratios in Two Soils and Their Effects Upon Yields and Nutrient Contents of German Millet and Alfalfa
Authors: McLean E. O. , Carbonell M. D.
Published: July 2010

A greenhouse study involving sequential cropping of two soils of differing cation exchange capacities (CEC) with five Ca‐Mg saturation ratios at two K levels was conducted. German millet (one cutting, Setaria italica, German) followed by alfalfa (five cuttings, Medicago sativa, Saranac) was grown with Mg‐Ca saturations varied from Mg 5%–Ca 75% to Mg 25%–Ca 55% at two K levels.

German millet yields were not affected by treatment of either soil. Similarly, alfalfa yields were not affected in the above range of Ca‐Mg saturations. However, an apparent Mg response occurred when alfalfa yields were more than doubled by increasing initial Mg and Ca saturations from 3 and 18% to 5 and 75%, respectively (concomitant pH increase from 5.4 to 6.8).

Magnesium contents of plant tissue increased with increased Mg saturation, but soil K depressed the Mg content of the tissues more per equivalent than soil Mg increased it. The results indicate that for most conditions, 6–10% Mg saturation (high to low soil CEC) would likely be adequate for maximum yields of crops, although 12–15% may be indicated for supplying adequate Mg when grasses are to be grown for use as the main dietary constituent of ruminants.

Exchangeable Mg and Ca contents in the soils after cropping plus amounts removed by cropping were less than the initial contents in one soil and were more than the initial contents in the other. Evidently some type of fixation mechanism tied up Mg and Ca in the former while solubilization of residual lime released them in the latter.
Rates of Growth and Nutrient Uptake of Irrigated Corn as Affected by N and P Fertilization
Authors: Bar‐Yosef B. , Kafkafi U.
Published: July 2010

Growth rates of corn and weekly uptake of major nutrients were measured in a permanent plot fertilization experiment. Bicarbonate‐soluble P and NO3‐N concentration in the soil were measured four times during the growing period. High levels of nitrates in the soil (140 ppm NO3‐N) during the first month of growth suppressed dry matter production. An increase in soil phosphate concentration resulted in higher phosphate uptake and early appearance of male flowers. On the control plots, which had not received any phosphatic fertilizer for 8 years, the plants took up more phosphate than the amount estimated by the bicarbonate method. The high levels of nitrates which were found in the soil 4 weeks after seeding (140 and 70 ppm N) dropped within the fifth week to a level of 20‐10 ppm N. Denitrification to gaseous compounds in the presence of living plants due to 68 mm of sprinkler‐applied water is proposed as an explanation of this phenomenon.

In order to support satisfactory plant development, the soil must be able to supply at least 900 mg N and 100 mg P per week to each plant. Uptake flux values for P and N ranged between 2.6 and 22.8 × 10‐6 µg P cm‐2 sec‐1 and between 4.1 and 22.5 × 10‐5 µg N cm‐2 sec‐1, and were affected by plant age and fertilizer application.
Readily Oxidizable Carbon: An Index of Decomposition and Humification of Forest Litter
Authors: Hu Lily , Youngberg C. T. , Gilmour C. M.
Published: July 2010

The forest floor is an important component of the forest ecosystem. The reactions taking place at this interface between the organic horizons and the mineral soil are strategic. The rate of CO2 evolution from the forest floor is indicative of the biological activity occurring in the organic horizons and is also indicative of the readily available energy material present. The amount of CO2 evolved over a 28‐day period was determined for the F‐layers (decomposing material) and H‐layers (humified material) from hardwood, conifer, and mixed hardwood conifer forests in the northeastern United States. Total CO2 evolved appeared to be indicative of the level of readily oxidizable carbon in the material and its state of decomposition and humification. A more rapid method of evaluating decomposition and humification appeared desirable. Water soluble carbon was determined on the same materials used for the CO2 evolution study plus fresh litter from some of the same stands. The values for soluble carbon compared very favorably with those from CO2 evolution determinations. It was thus concluded that the more rapid soluble carbon determination is a useful index of state of decomposition and humification.
Potentiometric Determination of Soil Organic Matter
Authors: Raveh Ariella , Avnimelech Yoram
Published: July 2010

The dichromate‐wet combustion determination of soil organic matter involves a titration of the excessive dichromate. A potentiometric titration is proposed. This modification enables a fast and accurate and point determination. Moreover, the method can be easily adapted for automatic titrations.
Microbial Competition for Glucose in Excised Root Experiments
Authors: Zwarun A. A.
Published: July 2010

Competition was determined by measuring 14CO2 evolution from the metabolism of 14C‐glucose by sterile roots or by roots with microflora present. Test solutions consisted of sterile 10‐4 M CaSO4 containing 1 µCi 14C‐glucose. A new technique was used to measure 14CO2. This technique does not rely on any wet chemical treatment and each analysis is completed in 72 sec. Treatments included sterile roots, nonsterile roots, and the microbial flora without roots. Sterile roots produced a low amount of 14CO2 from the 14C‐glucose. The nonsterile roots rapidly produced a copious amount of 14CO2. The low microbial inoculum without root material was dormant and did not produce any 14CO2. Apparently the microflora normally present during excised root experiments successfully competes with the root for glucose thus masking uptake attributable to the root.
Effect of Drying on Water Retention of a Puddled Soil
Authors: Taylor Howard M.
Published: July 2010

Mechanical energy applied to soil may disrupt the existing structure and increase water retention at a specific water potential. In this experiment, samples of puddled silty clay loam soil were predried to specified levels, then rewet. The effects of predrying on the water content‐potential relationships were determined.

Puddling substantially increased water retention of the soil. If the puddled samples were ovendried at 110C prior to testing, water retention at all potentials between −1/5 and −15 bars was similar to nonpuddled soils. If the samples were predried to any water potential more negative than the test value, then rewet to near saturation, their water retention reverted toward that of samples in the nonpuddled state.
Application of Multispectral Remote Sensing to Soil Survey Research in Southeastern Pennsylvania
Authors: Mathews H. L. , Cunningham R. L. , Cipra J. E. , West T. R.
Published: July 2010

Computer analyses of multispectral imagery collected from aircraft shows promise for reducing preparation time and increasing the accuracy of soil survey maps. The study area in southeastern Pennsylvania included soils formed from limestone, shale, sandstone, alluvium, and local colluvium. Four study sites ranging in size from 8.5 to 30 ha were selected from a 72 km flightline. Surface reflectance properties of nonvegetated fields were classified using pattern recognition techniques. Computer printout maps showing areal distribution of soil spectral classes were compared with field conditions. Limestone, shale, sandstone, and local colluvial soils were separated with a high degree of accuracy. Erosion classes separated by spectral maps were comparable in location and extent to field observations. The feasibility of preparing computer display maps for potential use as soil mapping aids was demonstrated.
Lindane Diffusion in Soil
Authors: Shearer R. C. , Letey J. , Farmer W. J. , Klute A.
Published: July 2010

Vapor and “nonvapor” diffusion of lindane was measured in Gila silt loam at various soil‐water contents. The apparent vapor diffusion coefficient (Dv′) increased rapidly as water content increased to 4%. There was a gradual decrease in Dv′ as water content increased from 4 to 20% and then a rapid decrease at water contents greater than 20%. The “nonvapor” apparent diffusion coefficient (Ds′) also reached a maximum at 4% water content and declined at water contents between about 4 and 20%. Ds′ increased as water content was increased above 20%.

Apparently diffusion in the “nonvapor” phase occurs at the water‐air and water‐solid interface as well as in the water. The contribution of these pathways to the total transfer is dependent upon water content. It was assumed that the water‐solid diffusion coefficient would be constant at water contents above 4%. The air‐water interface diffusion was highest at 4% water content and decreased at higher water contents. Diffusion in water was essentially zero at water contents below 15% and increased with increasing water contents above this value.
Effects of Some Urease Inhibitors on Urea Hydrolysis in Soils
Authors: Bremner J. M. , Douglas L. A.
Published: July 2010

Studies reported showed that, of eight urease inhibitors tested (2,5‐dimethyl‐p‐benzoquinone, catechol, p‐benzoquinone, hydroquinone, phenylmercuric acetate, N‐ethylmaleimide, sodium p‐chloromercuribenzoate, and acetohydroxamic acid), 2,5‐dimethyl‐p‐benzoquinone had the greatest ability to retard urea hydrolysis in soils and reduce gaseous loss of urea N as ammonia. Gaseous loss of urea N as ammonia from a urea‐treated sandy soil incubated at 20C for 14 days was reduced from 61.1% to 0.3% by addition of 2,5‐dimethyl‐p benzoquinone (2.3 parts/100 parts of urea).
The Chemistry of Fungal Humic Acid‐like Polymers and of Soil Humic Acids
Authors: Schnitzer M. , Ortiz de Serra M. I. , Ivarson K.
Published: July 2010

A. niger, E. nigrum, and S. chartarum were grown in glucoseasparagine media according to Martin et al. The fungal “humic acids” synthesized were isolated, purified, and characterized by elementary and functional group analyses and by permanganate oxidation of methylated preparations. The oxidation products were separated by extraction into organic solvents, followed by preparative gas chromatography. The major components were identified by mass spectrometry and microinfrared spectrophotometry. The experimental data for the fungal “humic acids” were then compared with those obtained by identical methods on soil and peat humic acids.

There were a number of similarities in surface functional groups between the fungal and soil preparations. The major oxidation products from the fungal materials were: (i) aliphatic mono‐ and dicarboxylic acids; (ii) benzenecarboxylic acids; (iii) phenolic acids; and (iv) aromatic compounds containing S and N. Compared with peat and soil humic acids, the fungal materials produced, per gram of initial material, relatively small amounts of aromatic but more aliphatic compounds. The E. nigrum “humic acid” yielded substantial amounts of n‐C14 to n‐C18 fatty acids. The results show that fungal “humic acids” are complex organic materials containing aliphatic and aromatic structures, only some of which are phenolic. Claims by Martin et al. that simple phenols and phenolic acids were significant constituents of fungal “humic acids” were not confirmed.
Ammonia Nitrogen Losses from Simulated Plowing of Native Sods
Authors: Hooker M. L. , Peterson G. A. , Sander D. H.
Published: July 2010

The objective of this research was to measure NH3 gas evolved from soils that have recently been broken from the native sod condition. Methodology for measuring NH3 losses under simulated natural environments is presented. Two moisture levels, field capacity, and wilting point were studied. It was concluded that NH3 volatilization was not a significant loss mechanism in the first 160 days after cultivation began.
Grain Fragmentation in Preparing Samples for Particle‐Size Analysis
Authors: Walker P. H. , Hutka J.
Published: July 2010

Some naturally occurring granular materials, such as granitic quartz and sand‐sized fragments of sedimentary rocks, are susceptible to breakage and may cause problems when present in soil samples being prepared for particle‐size analysis. An assessment was made of three methods of the kind used for disaggregating soils, with prepared samples of granitic alluvium and alluvium rich in argillaceous and quartzitic sedimentary rock fragments. An ultrasonic probe caused least fragmentation of the samples tested; an end‐over‐end shaker caused slight fragmentation of coarse fractions; a drink mixer operated for 15 min caused considerable fragmentation of medium and coarse‐sized fractions.
Soil Conditions Under Old Field and Forest Cover in Southern Illinois
Authors: Rolfe Gary L. , Boggess W. R.
Published: July 2010

A comparison of soil conditions under pine plantations and old fields of the same age was made for three loess‐derived soil types in southern Illinois. Native hardwood stands were used for comparing soil changes under the pine and old‐field seral stages. Characteristics studied included bulk density; hydraulic conductivity; organic content; pH; and exchangeable Ca, Mg, Na, K, and H. Under native hardwoods organic matter, pH, and exchangeable bases were higher, while bulk density was lower than under pine or old‐field cover. Under pine cover bulk density, hydraulic conductivity, and exchangeable base levels were improved over old‐field conditions, but organic matter was higher under the old‐field vegetation. No significant differences were noted in pH. The introduced pine seral stage has considerably ameliorated soil conditions since abandonment from agriculture, and there appears to be a trend toward conditions typical of native hardwood stands.
A Note on A Three‐Parameter Soil‐Water Diffusivity Function‐Application to the Horizontal Infiltration of Water
Authors: Parlange Jean‐Yves
Published: July 2010

A realistic water‐diffusivity function depending on three parameters was described recently by Ahuja and Swartzendruber (1972). An analytical solution for the horizontal infiltration of water and for such a diffusivity function is presented here. The result is expressed in terms of elementary functions and agrees very well with experimental observations.
Limitations of Darcy's Law in Glass Bead Porous Media
Authors: Boersma L. , Lindstrom F. T. , Saxena S. K.
Published: July 2010

In a series of dispersion experiments in porous systems made up of glass beads, it was found that for flow of water through small pores at low gradients, flow rates are not proportional to the hydraulic gradient but are proportional to this gradient raised to the power 1/n, where n > 1. These results agree with literature reports which have indicated that for flow through small pores, the flow fields undergo a change from Newtonian to non‐Newtonian behavior. The deviations have been attributed to force fields associated with the clay minerals, changes in the clay fabric making up the porous system, and electro‐viscous effects. In these experiments, the porous systems were made up of glass beads so that all effects attributed to clay‐water interactions could be ruled out. The functional relationship between the factor 1/n and pore radius r was found to be approximated by 1/n = 1 − exp(−1.32r0.31).
Cultural Practices for Irrigated Winter Wheat Production
Authors: Unger Paul W. , Allen Ronald R. , Parker Jessie J.
Published: July 2010

Rototilling, moldboard plowing, disking, burn‐listing, and listing were satisfactory tillage methods for managing the residues produced by continuous irrigated winter wheat (Triticum aestivum L.). Grain yields averaged highest for moldboard plowing and lowest for lister plowing. Nitrogen fertilizer at 90 or 135 kg N/ha resulted in significant grain and residue yield differences in a few years, but no consistent trends were apparent. Irrigation water infiltration was highest for moldboard plowing and lowest for lister plowing. The list and burn‐list treatments resulted in similar infiltration. Water‐use efficiencies were similar for all treatments.

At the end of the 5‐year study, soil organic matter content was lowest (1.66%) for burn‐lister tillage and highest (1.72%) for lister and disk tillage. Water‐stable aggregation was highest (84.5%) for rototilling and lowest (79.3%) for burn‐lister tillage. Bulk density increased in all plots, but it increased the least in plots that were moldboard plowed. Moldboard plowing resulted in the lowest (21.9) and burn‐lister tillage in the highest (28.6) percentage of fine aggregates (<0.42 mm). All treatments resulted in a relatively high percentage of wind‐erodible aggregates (<0.84 mm).

Applying 135 kg N/ha maintained soil organic matter and total nitrogen at higher levels than did 90 kg N/ha. Applying N soon after harvest of the previous crop generally was as beneficial as applying N at seeding. Soil bulk density, water‐stable aggregation, and dry aggregate distribution were not significantly affected by fertilizer treatments.
Diurnal Soil‐Water Evaporation: Chloride Movement and Accumulation Near the Soil Surface
Authors: Nakayama F. S. , Jackson R. D. , Kimball B. A. , Reginato R. J.
Published: July 2010

The movement and accumulation of chloride at shallow depths (0 to 9 cm) in a bare soil following an irrigation were studied under field conditions. Chloride accumulation in the 0‐ to 0.5‐ and 0‐ to 1‐cm depth increments followed a diurnal pattern but out‐of‐phase from the soil water content during the first few days after irrigation. The diurnal amplitude of chloride decreased with time as the soil progressively dried. At the 1‐ to 2‐cm and deeper depths, diurnal cycling of the chloride content was not measurable, whereas cycling in the water content was evident. Most of the total chloride accumulation at the shallowest depth occurred in the early stages of drying. However, chloride movement was detected as low as 4% volumetric water content or approximately −1,000 bars soil water potential.
A Comparison Between Mercury Injection and Nitrogen Sorption as Methods of Determining Pore Size Distributions
Authors: Sills I. D. , Aylmore L. A. G. , Quirk J. P.
Published: July 2010

A comparison of mercury injection and nitrogen sorption methods of pore size distribution analysis was made on a sample of goethite using the slit‐shaped pore model. Using the commonly accepted contact angle of 140° for mercury, the mercury pore‐size distribution plot is displaced by approximately 20% in plate separation with respect to the nitrogen plot. The assumption of a contact angle of 153° for mercury is required to make the plots coincide. This value is regarded as not unrealistic. Combination of the two techniques provide a useful method of pore size distribution analysis over a continuous range of pore sizes from 10Å to 50µm. This approach is particularly appropriate to the investigation of the pore structure of soil materials.
The Oxidation of Divalent Manganese Under Conditions Present in Tile Lines as Related to Temperature, Solid Surfaces, Microorganisms, and Solution Chemical Composition
Authors: Meek B. D. , Page A. L. , Martin J. P.
Published: July 2010

The oxidation and precipitation of Mn was measured in the laboratory under conditions similar to those present in tile lines. The presence of microorganisms capable of oxidizing Mn2+ was the most important factor controlling oxidation of Mn. These microorganisms were intimately associated with MnO2 collected from tile lines and could not be separated from the MnO2 particles. Hence, oxidation of Mn in the presence of microorganisms without the MnO2 could not be studied. Surfaces of sand or clay did not catalyze the oxidation. An increase in temperature from 20 to 30C increased the oxidation only slightly.

The effects of dissolved oxygen, soluble organic carbon, total salt content, pH, and bicarbonate over the concentration ranges occurring in tile lines were determined using solutions containing manganese oxidizing microorganisms. Soluble organic carbon and total salt content have no significant effect on manganese oxidation. The percent oxygen in the gas mixture did not affect the oxidation rate when it was varied between 1 and 21%. When nitrogen was flushed through the cylinders, the zero oxygen resulted in solution of Mn2+ from the manganese dioxide. When the bicarbonate level was raised to 9.0 meq/liter (4% CO2), the oxidation rate was 3 times the rate at the 5.3 meq/liter level of bicarbonate.
Direct Vaporization and Quantification of Arsenic from Soils and Water
Authors: Melton James R. , Hoover William L. , Ayers Jo Lynn , Howard Peggy A.
Published: July 2010

A procedure is described for the determination of arsenic in soils at the parts per million level and water at the parts per billion level. Determinations are made by direct introduction of arsine gas into the flame of an atomic absorption spectrophotometer. An easily constructed apparatus is described for introducing arsine into the flame. Soils from various states, as well as water samples from Texas waterways, are studied for arsenic content. Recoveries of arsenic added to soils and water samples ranged from 93.0 to 106.0%.
Formation of Dimethylnitrosamine, a Carcinogen and Mutagen, in Soils Treated with Nitrogen Compounds
Authors: Ayanaba Abateni , Verstraete Willy , Alexander Martin
Published: July 2010

Dimethylamine was formed from trimethylamine in a spodosol (pH 3.8), a silty clay loam (pH 5.8), and a silt loam (pH 6.5). Dimethylnitrosamine appeared if the soils were amended with the tertiary amine and nitrate or nitrite or with dimethylamine and nitrite. The amines were added to soil to a concentration of 50 and 500 ppm as nitrogen. The nitrosamine also was produced from the tri‐ or dimethylamine in the spodosol in the absence of supplemental inorganic nitrogen. The fungicide, thiram, was converted to dimethylnitrosamine in the spodosol treated with nitrate or nitrite. The identity of the nitrosamine was verified by ultraviolet spectrometry and thin‐layer and gas chromatography. Dimethylamine and dimethylnitrosamine disappeared with time from the soils.
Principles of Managing High Frequency Irrigation
Authors: Rawlins S. L.
Published: July 2010

The consequences of increasing irrigation frequency are explored, taking into consideration the laws governing water flow in soil. As frequency increases, the waterholding capacity of the soil becomes less important because water is supplied as the plants require it. Soil water content, and therefore matric potential, are continuously high and only slightly dependent upon deep percolation rate. This makes the need for deep percolation to leach salts the only valid criterion for applying more water than the plants transpire. The need to apply extra water to those crops that require high soil water content is eliminated. Controlling the deep percolation rate rather than the soil water status requires measurements of flux rather than water potential as inputs for managing the quantity of water to be applied.
Crop Residue, Soil Water, and Soil Fertility Related to Spring Wheat Production and Quality After Fallow
Authors: Black A. L.
Published: July 2010

Over an 8‐year period, wheat straw mulch rates of 0, 1,680, 3,360, and 6,730 kg/ha were established each spring of the fallow year in alternate crop‐fallow blocks in three replications on a Dooley sandy loam. Fertilizer subplot treatments applied before seeding spring wheat (Triticum aestivum L.) were as follows: Check, N, P, and N plus P. Both elements were applied at a rate of 34 kg/ha; N was applied each crop year, and P was applied initially and every other crop year thereafter.

After 14 and 21 months of fallow, average available soil water stored to a depth of 1.5 m increased significantly and was positively correlated with increasing residue levels. Each metric ton of surface residue increased average available soil water supplies 0.5 cm. Mean grain yields were positively correlated with stored soil water at seeding only when both N and P were applied. N‐P fertilization increased mean grain yields 410, 580, 690, and 760 kg/ha per year for corresponding residue levels of 0, 1,680, 3,360, and 6,730 kg/ha, respectively. A significant decrease in grain protein level associated with increasing residue level was caused by N dilution and was proportionate to the yield increases obtained with increasing residue levels within each fertilizer treatment. Residue treatments did not significantly influence total N uptake by grain plus straw at maturity. Grain protein levels could be increased and maintained near 15% with N or N‐P fertilization even though grain yield increased considerably.
Salts in Irrigation Drainage Waters: I. Effects of Irrigation Water Composition, Leaching Fraction, and Time of Year on the Salt Compositions of Irrigation Drainage Waters
Authors: Rhoades J. D. , Ingvalson R. D. , Tucker J. M. , Clark M.
Published: July 2010

The compositions of percolated drainage waters resulting from the use of eight synthesized river waters of the Western USA under conditions of alfalfa (Medicago sativa L.) production in a controlled lysimeter experiment are presented. The compositions are shown to be affected by (i) the composition of the river water used for irrigation; (ii) the fraction of applied water that appeared as drainage water; (iii) the presence or absence of soil CaCO3; (iv) whether or not the drainage water is open to the atmosphere, and (v) the time of year.
Air Entrapment as a Possible Source of Error in the Use of a Cylindrical Heat Probe
Authors: Nagpal N. K. , Boersma L.
Published: July 2010

The cylindrical heat probe is frequently used to measure the thermal conductivity of soils. Its theory is based on the assumption of zero thermal contact resistance at the probe surface. Noncompliance with this assumption could result from air entrapment at the probe surface, at the time of inserting the probe into the porous material. Results of studies are reported which show that the use of the heat probe can yield erroneous results which can be explained on the basis of air entrapment at the probe surface. Additional experiments were carried out to seek information regarding the relationship between thermal conductivity and soil water content for materials made up of different particle sizes. The porous media used consisted of three glass bead size fractions with diameters of 53–74, 74–105, and 149–210 µm obtained by dry sieving. Results of the experiments indicated that at the ambient temperature of 26C the relationship between thermal conductivity and water content was the same for the three size fractions. Experiments were not conducted at other ambient temperatures.
Nitric Oxide Sorption by Calcareous Soils: I. Capacity, Rate, and Sorption Products in Air Dry Soils
Authors: Prather R. J. , Miyamoto S. , Bohn H. L.
Published: July 2010

At room temperature, air dry calcareous soils sorbed from 0.5 to 2% NO by weight within 10 to 15 min from a dry air stream containing 1.6% NO by volume. The sorption capacity increased with 0.4 to 0.7‐th power of NO concentration and the soil specific surface and was independent of the soil acidtitratable basicity. The sorption rate was approximately proportional to the unused portions of the capacity with rate constants ranging from 0.4 to 1 min‐1. Less than 10% of sorbed NO was lost by heating at 105C or a suction of 65 cm Hg for 24 hours. The NO sorbed by the soil was converted to NO‐3.
Iron‐Induced Oranging Disease of Rice in Relation to Physico‐Chemical Changes in a Flooded Oxisol
Authors: Howeler R. H.
Published: July 2010

Soil conditions associated with an oranging disease which occurs in flooded rice (Oryza sativa) grown on the Oxisols of the Llanos Orientales of Colombia were studied by measuring changes in pH, Eh, and Fe and Mn levels in soil solutions after flooding. It was found that rates of reduction and the build up of Fe in the soil solution vary greatly for different Llanos soils, between virgin and previously‐cropped soils, and between air‐dried and field‐moist soils. Levels of Fe in solution could be reduced by various water management treatments and by the addition of large amounts of lime or MnO2. It was observed that oranging symptoms occur as solution Fe concentration increases and that large plants were more seriously affected than small plants. Roots of affected plants were heavily coated with oxidized Fe and few active white roots formed after the increase in Fe concentration. The disease appears to be due to indirect Fe toxicity, i.e., an Fe‐induced deficiency of mainly P, K, Ca, and Mg. Due to the relatively high level of Fe in solution, the roots become coated with iron‐oxide reducing the root's capacity to absorb enough plant nutrients from an already deficient environment.

Under certain conditions plants may also suffer from direct Fe‐toxicity, i.e., excessive Fe absorption by the plant, resulting in bronzing symptoms. A combination of direct and indirect Fe‐toxicity may produce plants with a wide range of intensities of oranging symptoms and brown streaks on the leaves.
Wind Erosion as a Factor in Soil Formation in the Pierre‐Shale Landscape of Western South Dakota
Authors: White E. M.
Published: July 2010

Slopes exposed to the prevailing NW‐SE winds in the Pierreshale landscape of western South Dakota have been eroded at a slow rate when vegetation was either destroyed by fire or weakened by drought since at least the Pleistocene. Slopes protected from the prevailing winds have had negligible wind erosion except in areas where severe erosion created deflation basins. These blowout basins are limited to small interfluve areas, a few square miles in size, which probably had a thick layer of loose, sand‐size fissile‐shale fragments that winds could erode. Soils in areas with blowout basins usually are more weakly developed, have shale at shallower depth, have little or no gilgai development, and appear to be younger than soils in comparable areas without deflation basins. Thus, the soil age in these areas is less than would be predicted from the geomorphic relationships to Pleistocene terrace systems. Soils in one area with deflation basins have development comparable to soils derived from late‐Wisconsin drift.
Transfer of Heat by Conduction and Vapor Movement in a Closed Soil System
Authors: Westcot D. W. , Wierenga P. J.
Published: July 2010

A study was made to determine the importance of vapor flow to the heat transfer process in soil. Soil temperature and water content were measured in sealed columns, 7.6 cm in diameter and 32 cm in length. The columns were inserted into a field plot and exposed to daily temperature fluctuations for periods varying from 1 to 6 days. A computer simulation model was developed to predict vapor movement and the transfer of heat by conduction and by vapor diffusion. Agreement was found between observed and computed water and temperature distributions in the columns. Comparison of observed and computed temperature profiles shows that for an accurate prediction of the soil temperature in the upper soil profile, heat transfer by vapor movement must be taken into account. Vapor flux accounted for 40–60% of the heat flux in the surface 0–2 cm of the soil profile during periods of the day. Vapor flux past the 11‐cm depth, depending on the time of the day, accounted for 17–34% of the total heat flux. Vapor flux still accounted for 20–25% of the total heat flux at the 25‐cm depth although the total heat flux density was no more than 10% of its surface value.
Oxidation of Ammonium to Nitrate in a Soil Column
Authors: Ardakani M. S. , Rehbock J. T. , McLaren A. D.
Published: July 2010

A mathematical model based on Michaelis‐Menten kinetics for oxidation of ammonium to nitrate during downward flow in a column of soil mixed with sand has been tested. First the column was perfused with nitrite to stimulate the growth of nitrite oxidizing microorganisms in order to decrease the concentration of nitrite at any time in the column during subsequent perfusion with ammonium. The nitrite oxidizers multiplied in a quasilogistic fashion to nearly maximal numbers, exceeding ammonium oxidizers by at least a factor of 102. After a population density of 103/cm3 was reached for NO2‐ oxidizers, the column was perfused with ammonium solution; in a steady state the ammonium concentration decreased with depth (proportional to time of flow) in accord with Michaelis‐Menten kinetics. The rate constants for oxidation of NH4+ were proportional to the numbers of ammonium oxidizing microorganisms extant at any given time of observation; these numbers increased exponentially at first but leveled off after about 3 weeks of continuous perfusion of the column.

As expected, the decline of ammonium concentration with depth during solution flow just equalled the appearance of nitrate with very low concentrations of nitrite in the steady state. From the data the normalized rate constant is 4.5 × 10‐3 ppm cm3/hour per microbe at room temperature, about five times greater than the corresponding figure for nitrite oxidation.
A Simple and Quantitative Greenhouse‐Laboratory Method for Injecting Gases into Soils
Authors: Hill Walter A. , Bohn Hinrich L.
Published: July 2010

A simple, rapid, and safe procedure for measuring ammonia gas accurately and injecting it into soils is described. The apparatus is easily assembled from readily available and inexpensive materials and could be used for many gases. The method is useful for laboratory, greenhouse, and classroom work.
Isolation of Soil Particle‐Size Fractions
Authors: Genrich D. A. , Bremner J. M.
Published: July 2010

Studies of the properties of soil particle‐size fractions have been restricted by the lack of a method of quantitatively isolating these fractions without serious modification of their properties. A mild method of isolating soil particle‐size fractions for such studies is described. It involves dispersion of the soil by ultrasonic vibration in water and subsequent isolation of the particle‐size fractions by sieving, centrifugation, and filtration techniques. The method allows large‐scale isolation of soil particle‐size fractions without use of chemical reagents, and it gives almost quantitative recovery of soil material in the fractions isolated. Data reported show that the particle‐size distribution values obtained for 13 soils after isolation of sand, silt, and clay fractions by the method described agreed closely with those obtained by particle‐size analysis after chemical dispersion by the peroxide‐sodium polyphosphate method.

Clay fractions isolated from soils by the physical method described had higher carbon, nitrogen, sulfur, and phosphorus contents and contained markedly higher percentages of the total carbon, nitrogen, sulfur, and phosphorus in the soils fractionated than did clay fractions isolated by another physical method that did not quantitatively separate clay‐size material.
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

Five 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

The 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

Allophane 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

Two 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

A 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.