bluuebunny/crossref_metadata_2025 huggingface dataset:
Response of Crops to Sulfur under Greenhouse Conditions
Authors: Gupta Umesh C. , Veinot R. L.
Published: July 2010

Two to four crops were grown in sequence in three series of pots on two soils, Charlottetown fine sandy loam (Chfsl) and Queens sandy clay loam (Qscl). The rates of applied S to the soils were: 0, 50, 100, and 150 ppm. None of the crops grown in the first sequence responded to S, but crops grown in later sequences responded to S in varying degrees. Sulfur applications resulted in about 2‐ to 4‐fold increases in the yield of rutabaga roots (Brassica napobrassica, Mill. cv. ‘York’). The plants deficient in S had thin roots and the leaves were reddish‐yellow with scorched edges. The kernel and straw yields of barley (Hordeum distichon L., cv. ‘Volla’) and wheat (Triticum aestivum L., cv. ‘Opal’) increased substantially with the addition of S. The S‐deficient plants of barley and wheat were lighter in color with thin stems. Alfalfa (Medicago sativa L., cv. ‘Saranac’) responded to S, with increases of much greater magnitude in the second and third cuts than those in the first cut. The S‐deficiency symptoms, noted as stunting and general yellowing of the entire plants, were mostly confined to the second and third cuts. Four‐ to five‐fold increases in cauliflower (Brassica oleracea botrytis L., cv. ‘Snowball’) yield with S3 and S4 treatments were obtained on Qscl, while on the Chfsl the yields decreased at S3 and S4 levels of S. The yield decreases on the Chfsl were caused by a severe Mo deficiency. Sulfur‐deficient cauliflower plants were stunted with general yellowing of leaf edges. The available soil SO4‐S levels of 2.0 and 2.4 ppm for alfalfa third cut and barley were in the deficiency range. The deficiency levels for wheat and cauliflower would likely be below 2.8 and 4.0 ppm, respectively.
Molybdate Adsorption Characteristics of Volcanic‐Ash‐Derived Soils in Chile
Authors: Gonzalez B. R. , Appelt H. , Schalscha E. B. , Bingham F. T.
Published: July 2010

Soils derived from volcanic ash in Chile present a high adsorption capacity for molybdate. Competitive studies with chloride, sulfate and phosphate suggest that molybdate has a high affinity for the adsorption sites in these soils. The mechanism involved on the adsorption of molybdate is qualitatively explained by the theories developed by Hingston et al. (1968, 1972) for anion adsorption by iron and aluminum oxides.

It is concluded that molybdate adsorption by volcanic‐ashderived soils is due mainly to the presence of allophane and amorphous aluminum, silicon and iron compounds and is not influenced by the organic matter content of this soil.
Influence of Sorbed Cations on Ammonia Retention Capacity of Tropical Soils
Authors: Shimpi S. S. , Savant N. K.
Published: July 2010

The NH3‐retention capacity of noncalcareous medium black soil and lateritic soil treated with 0.1N solution of HCl, AlCl3, MgCl2, CaCl2, NaCl or KCl followed the decreasing order: H‐soil ≈ Al‐soil > Mg‐soil ≈ Ca‐soil > Na‐soil ≈ K‐soil > check soil. The order of retention may be explained on the basis of formation of metal cation‐NH3 coordinated complexes having differential stability.
Effect of Daily Irrigation on Water Content and Suetion Profiles in Soils of Three Textures
Authors: Miller D. E.
Published: July 2010

A growth‐room study was conducted to evaluate the water and suction profiles that develop in various soils irrigated daily at different proportions of Et. When irrigated to just replace Et, the water profiles that developed depended upon the flow characteristics of the soil. In the soil in which water moved readily (Shano silt loam), water distribution was nearly uniform with depth and did not change with time. In the soils in which water moved slowly, either because of slow internal water movement when wet (Ritzville loam) or low unsaturated conductivities at relatively low suctions (Sagehill sand), the upper soil became wetter while the lower soil water decreased by a corresponding amount. In all soils irrigated daily to replace all or more than Et, suctions in the upper soil were relatively low. With the soil profile initially wet, several weeks of deficit irrigation passed before surface soil water content changed markedly.
Conventional and Controlled‐Release Nitrogen Sources for Rice
Authors: Wells B. R. , Shockley P. A.
Published: July 2010

Tests were conducted for the years 1967–1972 with rice (Oryza sativa L., cv. ‘Starbonnet’) to compare various formulations of sulfur‐coated urea (SCU) and iso‐butylidene diurea, (I.B.D.U.) with urea and ammonium sulfate as nitrogen sources on both silt loam and clay soils. The N sources were applied either preplant or topdress at rates up to 235 kg/ha to drill‐seeded rice which was flooded at approximately 2 weeks following seedling emergence. Grain yields, dry weight, and N uptake indicated that the controlled‐release N sources could be used to regulate rate of N supply to the plant throughout the growing season. Growth of direct seeded rice was slowed considerably during the early part of the growing season due to the slow rate of N release but grain yields were not drastically altered. Grain yields on the silt loam soils following use of the controlled‐release N fertilizers were consistently equal to those following use of urea or ammonium sulfate. On the clay soils under intermittent flooding, use of SCU resulted in increased yields as compared to urea applied preplant, and in one year resulted in increased yields as compared to urea applied in split top‐dress doses. Both SCU and I.B.D.U. were suitable N sources for rice growing under the water management systems employed in these studies.
Prediction of Imbibition in a Horizontal Column
Authors: Morel‐Seytoux H. J. , Khanji J.
Published: July 2010

An approximate analytical solution to the equations of water and air movement in a horizontal porous medium is presented. From the solution for the water content profile, imbibition rates can be predicted as a function of time. A comparison of predicted and experimental imbibition rates shows an excellent agreement. This result is particularly significant because no numerical integration of a differential equation is necessary to obtain the water content profiles and to obtain the imbibition rates. The method of solution requires only graphical constructions and integrations of curves simply related to the basic soil characteristics such as capillary head and unsaturated hydraulic conductivity.
Infrared Studies on Humic Acid in Deuterium Oxide: I. Evaluation and Potentialities of the Technique
Authors: MacCarthy Patrick , Mark H. B.
Published: July 2010

Infrared spectra of deuterated humic acid and sodium humate and the Cu(II), La(III), and Fe(III) complexes of deuterated humic acid were recorded in D2O medium. Changes in the 1550 cm‐1 to 1750 cm‐1 region of the humic acid spectrum which occur on salt‐ and complex‐formation were readily observed in the wet (D2O) slurry samples. Replacement of active protons in humic acid by deuterium (D) eliminates the broad O‐H absorption band which occurs in the 2900 cm‐1 to 3600 cm‐1 region of the spectrum of the H‐form of humic acid. Consequently, the aliphatic C‐H stretching bands which occur at 2860 and 2920 cm‐1 in the spectrum of humic acid are observed with negligible background absorption and with little interference from the O‐D stretching band which occurs in the 2200 cm‐1 to 2800 cm‐1 region. The deuterium‐proton exchange reactions in humic acid were found to be rapid.
Measuring Soil Creep
Authors: Troeh Frederick R.
Published: July 2010

Soil creep occurs so slowly that it is usually overlooked. Nevertheless, its persistence makes it significant to sciences that deal with soils or landscapes. Creeping soil can move landmarks and cause structures to tilt or collapse. But, the rate of movement by soil creep under various conditions is largely unknown. This paper describes a sensor that measures soil creep. The sensor is a sheet metal structure buried in a deep auger hole. Movement detectors mounted at four depths on the sensor are coupled to indicators at the soil surface to show how much movement has occurred. Readings from such sensors identify the location, depth, and rate of soil creep.
Dynamic Simulation of Water Storage in Fallow Soil as Affected by Mulch of Hydrophobic Aggregates
Authors: Hillel D. I. , van Bavel C. H. M. , Talpaz H.
Published: July 2010

A mechanistic numerical model, based on fundamental physical principles and written in IBM S/360 CSMP language, was designed to compute the dynamic balance of water in a fallow soil through repeated cycles of infiltration and evaporation. The necessary inputs are: (i) hydraulic characteristics of the soil and of the surface crust or mulch layer; (ii) duration and intensity characteristics of rainstorms or irrigations; and (iii) the potential evaporation rate as it varies diurnally and from day to day. The output provides time‐dependent rates and cumulative quantities of infiltration, runoff, surface detention, evaporation, internal drainage, and changes in water content of different layers and of the profile as a whole. Computations carried out for a 4‐day simulation (including two rainstorms and four evaporation cycles) illustrate the use of the model for uniform, crusted, or mulched soil; and predict that the presence of a mulch of hydrophobic aggregates, several centimeters thick, can greatly increase the quantity of water absorbed and retained in the profile. This finding accords with previously‐published experimental results and indicates a promising approach to soil management for water conservation in dryland and irrigated farming.
Humus Accumulation in a Forested Haploboroll in South‐Central New Mexico
Authors: Anderson J. U. , Silberman D. , Rai Dhanpat
Published: July 2010

A field study of a 65‐hectare area and a laboratory study of samples from two Boroll profiles and two Boralf profiles was conducted to determine why these extensive forested Borolls at high elevation have such an unusually high organic matter content. The study revealed that in these Rendzina‐like Borolls, organic litter decomposes much more slowly than in an adjoining Boralf, as indicated by differences in organic matter contents. This difference in rate of microbial oxidation does not depend primarily on nutrients supplied to the microorganisms or on invasion by locally indigenous microflora. Slow decomposition of Boroll organic matter probably results from protection afforded by its mixture with mineral soil in the gut of terrestrial snails (Ashmunella rhyssa).
Soil Strength and Aeration Effects on Root Elongation
Authors: Voorhees W. B. , Farrell D. A. , Larson W. E.
Published: July 2010

Primary root elongation rates of pea seedlings (Pisum sativa L. ‘Alaska’) and soil resistance to penetration of a probe were measured in remolded cores of sandy loam and clay soils over a soil water suction range of 0.1–1.0 bar. Physical soil resistance was varied by varying soil bulk density and water content. Primary root elongation was more closely correlated with soil resistance to a 10° probe than a 60° probe. It was also more closely correlated with soil resistance normal to the probe, which does not include soil‐metal friction, than with total point resistance which does include the friction component. While soil‐metal friction may not be equivalent to soil‐root friction, this correlation suggests that friction between root cap and soil may be negligible.

About 73% of the variation in primary root elongation was accounted for using normal point resistance to a 10° probe and including the effects of air‐filled pores in the bulk soil. Primary root elongation was most sensitive to air‐filled porosity at low levels of soil physical resistance.

Root length density increased as soil resistance increased due to increased production of first‐order laterals and decreased rooting depth.
Effect of Thinning on the Foliage and Forest Floor Properties of Ponderosa Pine Stands
Authors: Wollum A. G. , Schubert Gilbert H.
Published: July 2010

The longest and heaviest needle fascicles were associated with greater thinning intensities of ponderosa pine (Pinus ponderosa Laws.) stands 8 years after treatment. The foliar nutrient concentrations did not change significantly between the various thinning regimes. In addition the total forest floor in thinned and unthinned ponderosa pine stands ranged from 17.7 to 34.4 metric tons/ha. On a dry weight basis the F2 horizon constituted 74–88% of the total forest floor. However, nutrient concentrations increased from the foliage to the L to the F1 to the F2 which had the greatest concentrations of nutrients but were not affected by thinning intensity. The greater concentrations in the F2 were probably indicative of the more advanced degree of decomposition. Total nutrients in the forest floor were inversely proportional to the degree of thinning. In the stands at the growing stock level of 6.9 and 48.2 m2/ha (unthinned) total nitrogen was 213 and 301 kg N/ha, respectively. Other nutrient values were 17 and 27 kg P/ha, 18 and 32 kg S/ha, 56 and 75 kg K/ha, 119 and 154 kg Ca/ha, 75 and 126 kg Mg/ha, 26 and 34 kg Zn/ha, and 88 and 156 kg Mn/ha in the stands with growing stock levels of 6.9 and 48.2 m2/ha, respectively.
The Use of Urea and Sulfur‐Coated Urea for Corn Production in a Tropical Soil
Authors: Dalal R. C.
Published: July 2010

Placement of applied N at surface and at the 5‐cm depth at the rates of 50, 100, and 200 kg/ha of urea and sulfur‐coated urea (SCU) were used to measure changes in grain yield and N uptake by corn (Zea mays L.) grown during the wet season in Trinidad. SCU performed better than urea. Surface applied SCU was more efficient than when placed at 5 cm depth. Urea placed at 5 cm depth was more efficient in corn production than when applied on the surface.
The Influence of pH on the Adsorption of Phosphate by Soils from the Guinea and Sudan Savannah Zones of Nigeria
Authors: Mokwunye Uzo
Published: July 2010

An increase in pH of soils from the savannah zones of Nigeria to which varying quantities of phosphate were added increased the phosphate adsorbed by the soils. It is suggested that high pH increased the activity of hydroxy‐aluminum. Phosphate was adsorbed on the surface of the hydroxy‐aluminum species when the hydroxy‐aluminum‐phosphate attraction was strong enough to displace surface OH‐ ions.

As a result of increased P adsorption, the phosphate buffer capacity as well as the amount of phosphate required to attain a desired level of P in equilibrium solution increased. It is concluded that a successful liming program in the savannah soils must take into consideration increased phosphate fertilizer rates necessary for adequate nutrition.
Loess in Ohio in Relation to Several Possible Source Areas: I. Physical and Chemical Properties
Authors: Rutledge E. M. , Holowaychuk N. , Hall G. F. , Wilding L. P.
Published: July 2010

Thin loess deposits east of the Little Miami, Scioto, and Muskingum rivers in Ohio were investigated (i) to test the hypothesis that these river valleys were source areas for the loess that adjoins them, (ii) to determine if multiple loess strata occurred within any of the loess deposits, and (iii) to approximate, where possible, the geologic age of the loess. The loessial materials were investigated using morphological, chemical, and physical parameters. Particle‐size data were expressed on a fine earth and clay‐free basis. The fine earth basis was useful in detecting pedogenic development. Clay‐free data were used in establishing changes in parent material with depth and, perhaps more importantly, in development of relations between particle‐size and distance from proposed source areas.

Scioto and Muskingum river valleys were the chief source areas for the loess in the adjoining study areas, but the Little Miami Valley was not the primary source of the loess in the study area adjacent to it. Multiple loess deposits were identified only adjacent to the Muskingum River. All upper loess units were considered to be of comparable age; Late Wisconsin (Peoria Loess). The middle loess adjacent to the Muskingum River was considered to be Farmdale (Roxanna Silt) and the lower loess at the same site was considered to be Loveland loess (Loveland Silt) and contained a well‐developed Sangamon paleosol.
Translocation of Iron In Acid Sulfate Soils: II. Production and Diffusion of Dissolved Ferrous Iron
Authors: Harmsen K. , van Breemen N.
Published: July 2010

Field and laboratory data on one acid sulfate soil are used to compute the concentration of dissolved Fe2+ with depth and time by means of a mathematical model that considers simultaneous production and diffusion of aqueous Fe2+ during submergence.

Calculated ferrous iron concentrations compare well with concentrations measured in the course of 175 days at six depths down to 150 cm below the soil surface. Discrepancies between the model and field data for one depth may be attributed to mass flow induced by sampling of the soil solution.

The results are useful in interpreting the processes involved in the typical ferric oxide and jarosite accumulations observed in the B horizon of most acid sulfate soils in Thailand. During flooding small but significant amounts of iron diffuse towards the B horizon. The calculated fluxes of iron are too small to explain the observed ferric iron accumulation by diffusion of Fe2+ during the flooding period only. Diffusion and evaporative mass flow of Fe2+ liberated by pyrite oxidation in the C horizon during the dry season appear to be more important.
Bulk Density Sampler for Deep Soil Profiles
Authors: Holtzclaw K. M. , Rible J. M. , Pratt P. F.
Published: July 2010

A bulk density sampler, adapted from a conventional commercial type, was constructed and used to obtain soil samples at more than 50 sampling sites from depths to 30 m. This sampler increased the speed with which samples were taken because it was readily added to or detached from the drilling unit between sequences of drilling. Evaluations showed that the sampler obtained bulk density values quite comparable with those found with an undisturbed soil core method.
Determination of Soil‐Water Diffusivity for Anisotropic Stratified Soils
Authors: Sawhney B. L. , Parlange J.‐Y. , Turner N. C.
Published: July 2010

The unsaturated soil‐water diffusivity of an anisotropic soil can be described by a second‐order tensor. In the particular case of a stratified soil, the diffusivity tensor is defined by the two values of the diffusivity in the principal directions, one normal and one parallel to the soil layer. The standard method of Bruce and Klute then requires the use of two soil columns, one for each direction, to define the diffusivity tensor. The present method makes use of a two‐dimensional similarity solution first derived for an isotropic medium and extended here to a stratified soil. It is then possible to obtain the diffusivity tensor of the stratified soil from one experiment only. As an illustration of the method, the diffusivity tensor of a mica layer is measured and the result is used to analyze infiltration from a finite trench.
Influence of Long Term Tillage, Crop Rotation, and Soil Type Combinations on Corn Yield
Authors: Van Doren D. M. , Triplett G. B. , Henry J. E.
Published: July 2010

Studies to compare the relative ability of a wide range of tillage and crop rotation combinations (3×3 factorial) to sustain corn (Zea mays L.) production on several soils typical of Ohio were initiated in 1962. Soils were a well‐drained Wooster silt loam (Typic Fragiudalf), an imperfectly drained Crosby silt loam (Aeric Ochraqualf), a very poorly drained Hoytville silty clay loam (Mollic Ochraqualf), and a very poorly drained Toledo clay (Mollic Haplaquept). Tillage treatments were no‐tillage; plow and then plant; and plow, disk, and plant. Rotations were continuous corn, corn‐soybeans, (Glycine max L.) (2 year), and corn‐oats (Avena sativa L.)‐meadow (3 year) with each crop appearing each year in each rotation. Results are reported only for plots having equal plant density within a site‐year combination, and adequate weed control.

Corn yields were remarkably insensitive to tillage. The two plowed treatments had equal yield for virtually all years at each site within the same rotation. The no‐tillage treatment averaged 975 kg/ha or 13% lower yield than the average of plowed treatments on the Mollic Ochraqualf soil for 10 years of continuous corn, but had the same yield as the plowed treatments for the other two rotations. The no‐tillage treatment averaged 750 kg/ha or 10% greater yield than the average of plowed treatments on the Typic Fragiudalf soil for 11 years of continuous corn or corn‐soybeans rotation. Otherwise tillage treatments generally produced the same corn yield within site‐rotation combinations.
The Theoretical Interpretation of Field Observations of Soil Swelling Through a Material Coordinate Transformation
Authors: Sposito Garrison , Giraldez Juan V. , Reginato Robert J.
Published: July 2010

The nature of material coordinate transformations and their importance to the theoretical interpretation of time‐dependent data taken on swelling soil‐water‐air systems is discussed. A material coordinate transformation that is based on a special case of a general relation derived by Raats and Klute, but that has not yet been applied to swelling soil, is proposed as a useful expression with which to describe one‐dimensional soil water processes in the field. This transformation requires only the measurement of bulk density in time sequence from a set of one or more fixed points and, therefore, should be especially valuable when used in conjunction with dual energy gamma‐ray measurements of soil profile properties. An illustrative application of the proposed transformation is made to interpret dual energy gamma‐ray data on the swelling of Avondale clay loam.
Potassium Status of Selected Paleudults in the Lower Coastal Plain
Authors: Yuan T. L. , Zelazny L. W. , Ratanaprasatporn A.
Published: July 2010

An attempt was made to explain the lack of crop response to K fertilization for corn (Zea mays L.), soybean (Glycine max L.), and small grain in some Ultisols in the Lower Coastal Plain. Profile samples of a Rhodic Paleudult (Red Bay fsl), a Plinthic Paleudult (Dothan fsl), and Psammentic Paleudult (Eustis lfs) were analyzed for exchangeable K, nonexchangeable K which could be released, and total soil K. Although the first two forms of K were relatively low, a K reserve of about 1,500–2,800 kg/ha was found in each 15‐cm thickness of soil sampled throughout these soil profiles. Potassium may be released from this reserve as indicated by the hot 1N HNO3 extraction which produced an amount of K equivalent to 96 kg or better/ha for each 15‐cm soil depth. Chemical studies showed that this K was not associated with noncrystalline hydrous oxides, silicates, or phosphates. No K‐bearing minerals were evident in X‐ray diffractograms of clay fractions except after removal of noncrystalline material, but peaks for K‐feldspars were observed in silt fractions. Sodium pyrosulfate fusion method suggested that slightly < 50% of the K reserve occurred in the K‐feldspar form and most of the rest was probably in micaceous mineral forms.
Soil Reflectance Measurement Using a Photographic Method
Authors: Gold A. , Asher J. Ben
Published: July 2010

The albedo of two soils, Avondale clay loam and Yuma sand dunes, was determined using a panchromatic film in a hand‐held 35‐mm camera. Samples with different volumetric moisture content, from air dry to saturation, were compared to calibrated reference surfaces of evenly distributed tones of gray. For the limited spectral sensitivity of the detector (panchromatic film), a correction factor K′ was derived graphically from known spectral reflectance of a different soil. The albedo is given by the product of the correction factor and the fraction of the reflected radiation that contributes to the detector signal. The results obtained by the photographic method were in good agreement with results obtained by conventional radiometric methods for Yuma sand dunes, but larger differences were found between radiometry and photography for Avondale clay loam.
Exchange and Hydration Properties of Cu2+ on Mixed‐ion Na+‐Cu2+ Smectites
Authors: McBride Murray B.
Published: July 2010

The exchange of Na+‐montmorillonite with Cu2+ was studied using X‐ray diffraction, electron spin resonance (esr) and a specific Cu2+ electrode in order to investigate the hydration and exchange properties of mixed Cu2+‐Na+ clay systems. With < 30% of the exchange sites occupied by Cu2+, the clays behave much as pure Na+‐montmorillonite and swell freely in water. Larger exchange levels of Cu2+ produce more ordered interlayers at low relative humidities. At high relative humidities, this ordered structure is reduced and a solution‐like environment is produced as the aluminosilicate sheets further separate. Exchange isotherms demonstrate a large preference for Cu2+ over Na+ at low Cu2+ exchange levels but preference for Na+ at high Cu2+ levels. In contrast, Cu2+‐Mg2+ exchange does not show this effect, indicating that certain exchange sites on the silicate structure preferentially adsorb divalent cations. Thus, Cu2+ ions are effectively removed from solution by Na+‐montmorillonite, but are not adsorbed in preference to other divalent cations.
Urea and Ammonium Sulfate Fertilization of Potted Slash Pine under Two Soil Moisture Regimes
Authors: Sarigumba T. I. , Pritchett W. L. , Smith W. H.
Published: July 2010

Two‐year‐old slash pine seedlings grown in lysimeter pots, filled with a Spodosol, received three levels of N from two sources, (NH2)2CO and (NH4)2SO4, under two soil moisture regimes. Tree growth was greater when soil matric suction limit was set at 170 cm than at 500 cm of water. Slash pine growth response was greater to (NH2)2CO than (NH4)2SO4. Urea fertilization resulted in greater nutrient uptake by the seedlings during a 9 month period. On the other hand, (NH4)2SO4 favored higher nutrient leaching losses. In general, where growth response was best, nutrient uptake was greatest and leaching losses were least.
A Background Temperature Correction for Thermal Conductivity Probes
Authors: Jury W. A. , Bellantuoni B.
Published: July 2010

A procedure is outlined for correcting the thermocouple reading of a thermal conductivity probe for changes in temperature caused by external warming or cooling of the soil during the period of measurement. A background temperature measurement is made for several minutes with the probe heater turned off, and the estimated temperature change due to the surroundings is then subtracted from the change caused by the probe heater. A laboratory experiment using a buried probe exposed to surface heating demonstrated a substantial reduction in the errors for the values of conductivity measured for a soil of known thermal properties when the correction was used.
Adsorption of Dodecylbenzene Sulfonate on Na+‐montmorillonite: Effect of Salt Impurities
Authors: Clementz David M. , Robbins John L.
Published: July 2010

The adsorption of purified dodecylbenzene sulfonate (ABS) on Na+‐montmorillonite follows the Langmuir isotherm, reaching a maximum amount adsorbed which corresponds to the anion exchange capacity of the clay. When a commercial grade ABS (containing 60% Na2SO4) is used, the adsorption process is more complex and occurs in two distinct steps. In dilute solutions, the salt impurity has a minor effect on adsorption and the result is essentially the same as that obtained for the purified surfactant. However, as the salt concentration is increased to a given value, enhanced adsorption due to hemimicelle formation occurs.
Stimulation of Plant Growth by Humic Substances
Authors: Lee Yong Seok , Bartlett Richmond J.
Published: July 2010

Humic substances prepared by different techniques of extraction and from different sources of organic materials were tested for their effects on growth of corn seedlings and algae. Stimulating effects were confirmed with optimum concentrations about 5 ppm C as Na‐humate for corn and 60 ppm for algae. With corn, the increase was 30 to 50% in nutrient solution or low organic matter soil; with algae, about 100%. Variation of effects among humic acids derived from different organic materials was not great.

The concentrations of elements in corn seedlings did not show any correlation with yield or humic acid level except for P and Fe. Phosphorus concentration was increased with increasing levels of humic acid regardless of the yield response. Higher Fe concentration in the plant tops and lower in roots was observed in the treatments with humic acid.

The application of humic acid to a soil low in organic matter or to nutrient solution gave the greatest growth response. Application to a high organic matter soil gave little growth response, or even a slightly negative response, indicating that the natural soil, without extraction, supplied optimum amount of humic substances to the plants. It is suggested that a test be developed to predict whether a given soil can furnish an optimum level of humic substances.

Different humic substances showed different degrees of stimulation of algal growth, with the most stimulation from a mixture of humic and fulvic acids. Humic substances in paddy soils may affect the growth of beneficial algae and of the rice (Oryza sativa L.) itself. As pollutants, humic substances may stimulate undesirable algal growth in bodies of water.
A Centrifugal Filtration Method for Isolating Rhizocylinder Solution
Authors: Soon Y. K. , Miller M. H.
Published: July 2010

To measure the phosphate concentration in the soil solution adjacent to plant roots, a method of isolating the rhizocylinder solution was developed. A major factor in the choice of a method is that it should be rapid and should not alter the solution salt concentration during isolation. The centrifugal filtration method satisfies both conditions for bulk soil samples; it was subsequently applied to the rhizocylinder (roots plus adhering soil). Root sap leaking from corn (Zea mays. L) roots during centrifugation introduced a significant error in the rhizocylinder solution phosphate concentration for a sandy loam with a low solution phosphorus concentration. For two medium‐textured soils with a higher solution P concentration, the error was negligible. The method is considered suitable for the latter soils.
Contribution of Lateral Soil Water Movement above a Fragipan to Streamflow
Authors: Palkovics W. E. , Petersen G. W.
Published: July 2010

A water balance approach to the hydrologic budget on a small mountainous watershed in central Pennsylvania was used to determine if lateral water flow perched above a soil fragipan could be quantitatively related to streamflow. Perched water table fluctuations were measured using a grid of 60 observation wells and streamflow was recorded using a weir. This site was monitored in mid‐November when evapotranspiration was at a minimum and when no precipitation was recorded. Soil water yield due to perched water table decline was calculated, hydraulc conductivity and the rate of water movement through the soil computed, and the zone of water contribution to streamflow determined. Results indicated water yield from the soil aquifer explained streamflow. Saturated water flow was shown to be the main mechanism of water movement, although unsaturated flow may have been significant for short distances under low tensions. The major zone of soil water contribution to streamflow was the more poorly drained soils adjacent to the stream. Unsaturated soils on the upper mountain flanks had little affect upon streamflow because of their low gradient and their large distance from the stream.
Soilscape Analysis of Slightly Contrasting Terrains in Southeastern Wisconsin
Authors: Pavlik Hannah F. , Hole Francis D.
Published: July 2010

Fabric analysis using detailed soil maps and modal soil descriptions was made of two contrasting ground moraine terrains, with and without drumlins, respectively, in southeastern Wisconsin. Heterogeneity within soil bodies was acknowledged, but the landscapes were contrasted primarily on their distribution of soil mapping units. Comparison and reclassification was achieved by multivariate discriminant analysis procedures using 29 variables derived from consideration of 18 soil body characteristics. Results of the study also included population density of soil bodies; range in relief; relative dominances of soil drainage classes, of soils formed in alluvium and colluvium, of loess thickness classes among upland soils, and of soil series. These were characterized independently of the computer analysis.
Soil Deterioration on Campsites: Northern Forest Types
Authors: Legg Michael H. , Schneider Gary
Published: July 2010

Camping use and soil deterioration were monitored on 12 campsites in northern Michigan during their third and fourth camping seasons. Sites were on previously undisturbed Gogebic fine sandy loam (Typic Fragiorthod), under mature northern forest cover. Percentage of litter cover, soil macropore space and depth to A2 horizon decreased, and soil bulk density increased with time during both use seasons. Deterioration increased greatly on all campsites with intensity of use. Except for depth to A2 horizon, measured parameters recovered partially over winter, but recovery was less than deterioration during the previous summer.
Determination of Soil Aluminum in Barium Chloride Extracts by Aluminon Method
Authors: Khalid R. A.
Published: July 2010

Barium chloride solution used to extract soil Al was found to react with an aluminon reagent to form aluminon lake as does Al and enhance color intensity. It is suggested that in soil extracts where aliquots required for Al determination are < 10 ml, additional 1N BaCl2 should be added to give a constant total quantity of 10 ml BaCl2 in all extracts. In soil extracts with low Al concentrations, where aliquots larger than 10 ml are required for analysis using the aluminon method, no corrections for BaCl2 interference are necessary.
Variation of Selected Properties across a Soil Boundary
Authors: Campbell James B.
Published: July 2010

This study is a statistical analysis of the changes in the distributions of soil properties at the contact between two soil series. Samples were collected at 10‐m intervals on an 18 by 40 grid positioned over the mapped boundary between two contrasting soil series in eastern Kansas. Samples collected from the B2 horizons of both soils were analyzed for gravel, sand, and silt content, for pH, and for Munsell color. These measurements were used to calculate a discriminant function which was used to define the boundary between the two soils. The variations of sand, silt, and pH measurements were compared with each of three models describing changes within the study area. The first model is a random distribution of the measurements. Simple trend surfaces were calculated for each of the three sets of measurements as a second model. A third model consisted of two uniform categories separated by an abrupt boundary. The fit of each model was tested against the distributions of the three sets of measurements using autocorrelation functions to examine the distributions of the residuals. The simplest model having random variation in the residuals was selected as the most efficient descriptor for each variable. Trend models were selected for the pH and silt measurements; and the two‐category model was selected for the sand data. This indicates that measurements of pH and silt change slowly within the study area, whereas the sand measurements exhibit a very sharp change at the contact between the two soils.
Effects of Beef Cattle Manure on Water‐stability of Soil Aggregates
Authors: Mazurak A. P. , Chesnin Leon , Thueel A. Amir
Published: July 2010

A field experiment was established to determine the effect of applying varying large amounts of manure on (i) the size distribution of water‐stable aggregates and (ii) their resistance to dispersion during prolonged periods of shaking in water. It was hypothesized that the formation of highly water‐stable aggregates as a result of organic matter amendments to the soil took a relatively long period of time to occur.

Beef cattle manure was applied at rates of 0, 180, and 360 metric tons/ha for 3 consecutive years to a Sharpsburg silty clay loam soil in eastern Nebraska. One year after the third manure application, soil samples were collected from the 0 to 10 cm depth of soil and air dried. Aggregates of 4,760–9,440 µm in diameter were wetted under vacuum and then shaken in water for 2, 20, and 200 min. The size distribution of aggregates in water was measured using pipette, elutriators, and sieves.

Increased rates of manure application increased the percentage of water‐stable aggregates >295 µm in diameter and decreased the percentage in size groups 18.5–295 µm and <18.5 µm in diameter after 2‐ and 20‐min shaking periods. Distribution of aggregates present after 200 minutes of shaking was not affected by levels of manure application to the field plots.
Effect of Irrigation Systems on the Water Requirements of Sweet Corn
Authors: Wendt C. W. , Onken A. B. , Wilke O. C. , Hargrove R. , Bausch W. , Barnes L.
Published: July 2010

A field study was conducted to determine the influence of sprinkler irrigation (Sp), furrow irrigation (F), subirrigation (Su), and automated subirrigation (ASu) on the water requirements of sweet corn (Zea mays L.). Irrigation water was applied to the SP, F, and Su plots when the soil water potential at the 30‐cm depth in the row reached −40 cbars potential. The time and amount of water applied was based on a combination of leaf area index (LAI) and potential evapotranspiration (ETp). Water application to the ASu plots was controlled by a switching tensiometer 30 cm deep set at −40 cbars potential. Soil water content changes were determined by gravimetrically sampling the surface 15 cm and obtaining neutron probe measurements of water in the deeper depths.

Significant differences existed in the irrigation water requirement of the sweet corn irrigated by the different systems (F = 351 mm, SP = 248 mm, Su = 248 mm, ASu = 142 mm). However, little difference in consumptive use occurred between systems (F = 361 mm, Sp = 346 mm, Su = 346 mm, ASu = 310 mm) due to differences in soil water utilization. Automation of irrigation systems offers the possibility of significantly enhancing irrigation water use efficiency in supplementally irrigated areas.
Determination of Terrestrial Albedo from Landsat I Satellite Imagery in Photographic Form
Authors: Ben‐Asher J.
Published: July 2010

Satellite imagery taken from Landsat I were used to determine terrestrial albedo and its changes with location and season in the basin of Sonoita Creek (31°45′N 110°43′W). A simple linear equation was derived to link the albedo with the optical density of the imagery. The modeling approach was based on the cyclic nature of the energy exchange between earth and space on the one hand and on the local density on the developed film as an output on the other hand. The results showed acceptable agreement between photographic and radiometric method for albedo determination.
Water Movement in Bare and Cropped Soil Under Isolated Trickle Emitters: I. Analysis of Bare Soil Experiments
Authors: Jury W. A. , Earl K. D.
Published: July 2010

A field experiment on a Buren sandy loam with a low (0.5 cm/hr) saturated hydraulic conductivity is reported in which water movement in soil irrigated from a single isolated trickle emitter was observed. Water was introduced at a uniform rate of 4 liters/hr and a weekly volume of 84 liters at frequencies of 3 irrigations/day and 1 irrigation/week. During a 41‐day experiment, soil water movement was followed by tensiometers and gravimetric water content sampling, and surface ponding was recorded by photography. It was found that more water moved laterally in the weekly irrigation plots than in the daily ones, a result which was not consistent with predictions of simplified theoretical models which did not consider surface ponding. Observation of the wetted radius at the surface indicated that substantial amounts of water were running off laterally during the weekly irrigation, which could account for the storage changes seen at large radial distances from the emitter.
The Effect of Split Nitrogen Applications on Nitrogen Uptake by Pensacola Bahiagrass from an Aeric Haplaquod
Authors: Blue W. G. , Graetz D. A.
Published: July 2010

An experiment was initiated with an established ‘Pensacola’ bahiagrass (Paspalum notatum Flugge) sod on Myakka fine sand (sandy, siliceous, hyperthermic Aeric Haplaquod) that had been used in a 10‐year experiment with N fertilizers. Five lime treatments were used in the previous experiment as main plots, with three N rates (0, 112, and 224 kg of N/ha/year) as subplots, and five N sources (calcium nitrate, ammonium nitrate, ammonium sulfate, urea and ureaform) as subsubplots.

The current experiment was established to determine the effect of the number of N applications on N uptake efficiency in Pensacola bahiagrass forage with particular emphasis on rainfall amounts and distribution. The original experimental design was used except that treatments which had 1, 2, 4, 8, and 16 N applications/year replaced the N source variable on the sub‐subplots. Nitrogen rates were retained as in the original experiment. The experiment was conducted for 3 years.

Nitrogen uptake in forage was relatively efficient ranging from 64 to 79%. There was little difference among treatments involving number of N applications. Generally, 1 or 16 applications were slightly superior to treatments involving two, four, or eight applications. Nitrate‐ and NH4+‐N concentrations in soil solutions higher than those from the control treatment were found only in March and April 1973 when initial N applications were followed by 202 mm of rainfall within a 12‐day period. This coincided with low N recovery in forage, particularly from treatments involving one or two N applications since all or one‐half of the annual N supply for these two treatments had been applied prior to this relatively intense rainfall.
Micronutrient Concentrations in Soil Solution After Ammonium Phosphate Applications
Authors: Mortvedt J. J. , Osborn G.
Published: July 2010

Two fluid ammonium polyphosphates, 11‐17‐0 (11‐37‐0 oxide basis), a commercial 10‐15‐0 (10‐34‐0), and an equimolar mixture of mono‐ and diammonium phosphate (MAP‐DAP), each with a solution pH of about 6.2, were well mixed with 1‐kg lots of several soils to supply 2,000 ppm of P, which approximates the P concentration in soil near a fertilizer band at a P rate of 50 kg/ha. Each soil was then moistened to 0.2 or 0.3 atm and stored in plastic bags. After periods up to 28 days, soil samples were placed in a lucite cell and a portion of the soil solution was expressed by N2 gas. These solutions were analyzed for Cu, Fe, Mn, Zn, organic C, and total and orthophosphate P.

Micronutrient concentrations in solutions of acid soils were temporarily increased by both ortho‐ and polyphosphates. Increases were related in part to the amount of soil organic matter solubilized by these fertilizers. Organic C in solutions of treated soils increased in the order: MAP‐DAP, 10‐15‐0, and 11‐17‐0, which was related to the original percentage of the total P in polyphosphate form (0, 50, and 78, respectively). Micronutrient concentrations in solutions of acid soils were highest during the first week and decreased to those in untreated soil by 28 days. Soluble micronutrient concentrations in neutral and calcareous soils were not affected by phosphate applications even after 1 day. Thus, solubilization of soil micronutrients by polyphosphates does not appear to play an important role in micronutrient nutrition of crops, especially in calcareous soils.

Phosphorus concentrations in soil solution generally were higher in soils treated with ortho‐ than with polyphosphates. Decreasing polyphosphate concentrations in solutions of polyphosphate‐treated soils with time indicated hydrolysis and precipitation of water‐soluble polyphosphates; less than 25% of the soluble P was in polyphosphate form after 2 weeks, with higher polyphosphate concentrations found in 11‐17‐0 than in 10‐15‐0 treated soils during the first 2 weeks after application.
Acidic Properties of Kaolinite in Water and Acetonitrile
Authors: Loeppert R. H. , Zelazny L. W. , Volk B. G.
Published: July 2010

Potentiometric titration of weakly acidic sites on soil clays is limited in aqueous media by the acidic property of water which prevents sharp endpoints. Generally, it is not possible to obtain sharp endpoints in aqueous systems for acids with pKa > 8. In this study, kaolinite with K, H, or Al as the saturating cation was successfully titrated in water and acetonitrile using the glass‐calomel electrode system for potentiometric determination. Sharper endpoints and wider working potential ranges were obtained in acetonitrile than in the aqueous system. Titer of base needed to reach the final endpoint was greater in acetonitrile than in water; for example, K‐saturated clay required a negligible titer in water (0.4 meq/100 g clay) in contrast to acetonitrile, in which a significant titer (7.4 meq/100 g clay) was required. The larger titer in acetonitrile was attributed to (i) pH‐dependent sites for which a quantitative endpoint was not obtained in water due to the acid‐base properties of this solvent, and (ii) an increased surface acidity in acetonitrile. A comparable difference in total titers at the final endpoint was observed for the titration of H‐ of Al‐saturated kaolinite in water and acetonitrile.
Winter Wheat Recropping on Dryland as Affected by Stubble Height and Nitrogen Fertilization
Authors: Black A. L. , Siddoway F. H.
Published: July 2010

Although crop‐fallow systems stabilize production in the semiarid northern Great Plains, fallow often wastes water, minimally controls water and wind erosion, and contributes to the saline‐seep problem. Developing alternate cropping systems which rely less on fallow requires additional crop residue and more specific soil fertility management guidelines. To optimize the potential of a spring wheat‐winter wheat‐fallow rotation for the northern Great Plains, we examined the effects of spring wheat (Triticum aestivum L. ‘Norana’) stubble management (conventional‐till vs. no‐till stubble at heights of 15, 28, and 38 cm) and N fertilization (rate, timing, and source) on winter wheat yields. Grain yields were significantly higher for ammonium nitrate (NH4NO3) than for urea applied at 67 kg N/ha early (1 May) or late (23 May). Maximum grain yields were 2,620 and 2,540 kg/ha for winter wheat seeded directly (no‐tillage) into 15‐ and 28‐cm stubble heights, respectively, with 67 kg/ha of N applied in early May as NH4NO3. With 22 or 45 kg/ha of N applied early (1 May), grain yield increases for NH4NO3 and urea were similar. With a later application at the same rates, NH4NO3 was significantly superior. Nitrogen topdressing of winter wheat in a recropping system must be completed early, either before or soon after spring growth begins and definitely before the end of tillering.
A Mechanically Controlled Variable Rate Leaching Device
Authors: Holmgren George G. S. , Juve Robert L. , Geschwender Robert C.
Published: July 2010

Twenty‐four leaching tubes attached to 60‐ml plastic syringes are mounted on the periphery of three vertically aligned slotted discs 45 cm in diameter. The plungers are withdrawn at a controlled rate by a variable speed screw jack that separates the two lower discs holding the plungers and syringe barrels, respectively. Leaching time can be varied from 15 min to 12 hours or more. The final volume of extract is determined by weighing the syringes. Precision of ammonium acetate CEC and extractable cations by this procedure with 2.5 g of soil and 50‐ml extract matches that of a comparable manual method using vacuum extraction with 5 g soil and 100 ml of extract. This apparatus has also cut required operator time in half.