bluuebunny/crossref_metadata_2025_split huggingface dataset:
Green Manuring and Crop Residue Management in Rice Production
Authors: Williams W. A. , Finfrock D. C. , Davis L. L. , Mikkelsen D. S. 
Published: July 2010

AbstractA series of field experiments were conducted to determine the nature of the effects of green manures and rice crop residue management on lowland rice production. Winter leguminous green manure was determined to be an inexpensive, efficient source of nitrogen which fits in well with continuous rice culture in the Mediterranean type climate of California. The marked response of rice to leguminous green manure was duplicated, for the most part, by inorganic nitrogen applications when properly placed in the reducing zone of the rice soil.Leguminous green manure served to add nitrogen to the highly carbonaceous rice crop residues. This permits decomposition to proceed without tying‐up nitrogen needed by the subsequent crop, and provides a satisfactory alternative to the deleterious practice of burning the residues.
Effect of Tile Spacing on Crop Yield and Water Table Level in a Planosol Soil
Authors: Schwab G. O. , Kirkham Don , Johnson H. P. 
Published: July 2010

AbstractSix years of data are presented on the effect of tile drainage in a Planosol soil (claypan soils of flat lands) at spacings of 15, 30, and 60 feet. Corn, oats, and hay yields were obtained as well as water table levels, rainfall, tile outflow, soil texture, and soil hydraulic conductivity measurements. Corn and oat yields on the 15‐ and 30‐foot spacings varied from 3.4 to 9.1 bu. per acre higher (significant at 99% probability) than the yields on the 60‐foot spacings. Water table, outflow, and hydraulic conductivity measurements seem to indicate that water movement to the tile is largely through the more permeable backfill over the drains. The initial water table midway between the drains a few hours after a rain is lower for the narrower spacings; subsequently, the rate of drop is nearly the same for all spacings. After the first day following rainfall, evapotranspiration and other losses appear to influence the rate of drop more than the tile. Between the drains the water table is nearly flat. After the soil is saturated, tile outflow increases rapidly within a few minutes after the rain starts and reaches a peak in 2 to 4 hours. Several peak flows of over 1 inch per day were recorded. The maximum tile outflow volume measured for a given storm was 55% of the rainfall; however, this percentage is influenced greatly by antecedent moisture conditions.
Hydrodynamic Dispersion of Solutes in the Soil Moisture Stream
Authors: Day Paul R. , Forsythe Warren M. 
Published: July 2010

AbstractThe soil moisture stream is characterized, even in the simplest cases, by a heterogeneous velocity pattern that affects the movement of dissolved solutes. The solutes are carried by the moving stream at diverse rates, causing a spreading action whose amount depends upon the detailed pattern of the flow.The amount of dispersion (σd) in unidirectional flow is proportional to the square root of the linear displacement of fluid. The proportionality constant is a characteristic of the flow system and can be determined experimentally. The amount of dispersion obtained for a given amount of linear displacement is theoretically independent of the velocity of flow. Experiments supporting this conclusion are cited.The experiments with ion exchange resin described herein indicate that the free ions are translocated in accordance with Scheidegger's probability theory. One concludes that the movement of dissolved solutes in the soil moisture stream cannot be determined adequately from the average fluid velocity unless the hydrodynamic dispersion effect is taken into account.
Soil Potassium‐Moisture Relations: I. Potassium Release Observed on Drying Iowa Soils With Added Salts or HCl
Authors: Scott A. D. , Hanway J. J. , Stickney E. M. 
Published: July 2010

AbstractIncrements of salts or HCl were added to field‐moist samples of selected Iowa soils. The soils were then dried and extracted with neutral 1N NH4Ac to determine the K released under these conditions.When no salt or HCl was added, there was a continuous increase in K release when the moist soils were first dried at room temperature and then at progressively higher temperatures. The release of K at elevated temperatures appears to be part of the same extractable K‐moisture relationship that has been observed when soils are airdried.Soils that normally released K on drying showed a continuous net fixation of K on drying when enough KCl was added to the moist soil. When lesser amounts of KCl were added both fixation and release were observed in the same drying sequence. The release of K was reduced when NH4Cl, NaCl, or HCl was added to the soil prior to drying. The NH4Cl additions were particularly effective. CaCl2 additions had little or no effect on the K released by drying.
Soil Potassium‐Moisture Relations: II. Profile Distribution of Exchangeable K in Iowa Soils as Influenced by Drying and Rewetting
Authors: Hanway J. J. , Scott A. D. 
Published: July 2010

AbstractExchangeable K was determined in “moist,” air‐dry, and oven‐dry samples from profiles of different Iowa soils. All moist subsoil samples contained low amounts of exchangeable K. Drying increased the exchangeable K in all of the samples, but in general, the subsoils released more K on drying than the surface soils. Thus, the profile distribution of exchangeable K depended upon the moisture content of the soil samples at the time of extraction.No relation existed between the amount of K released on drying and the amount of released K that reverted to fixed form when the soils were subsequently stored under moist conditions. There was more reversion of K to fixed form in the Marshall profile samples and in samples from below 3 feet deep in the Carrington, Fayette, and Edina profiles than in samples from the upper 3 feet of these profiles. This indicates that greater reversion occurs in the least weathered material. In some cases reversion occurred in the oven‐dried samples but not in the air‐dried samples.
The Weathering of Some Boron‐Bearing Materials
Authors: Graham E. R. 
Published: July 2010

AbstractThe weathering properties of several boron‐containing minerals and materials were studied for their solubilities and reactions in water and their exchange reactions in contact with clay.The amounts of boron released from the minerals Howlite, Bakerite, Colemanite, Tourmaline, and boron frits, 176‐E and 176‐F, some commercial preparations, were investigated by treating these materials with distilled water at room temperature, hot distilled water as in a Soxlet extraction, hydrogen‐saturated IR‐120 amberlite, Putnam clay, and sodium EDTA. The bakerite and tourmaline minerals were studied for the availability of the mineral‐held boron as demonstrated by growing alfalfa plants in sand‐clay cultures that had received treatments of these minerals as a source of boron.The amount of boron released was related to the nature of the mineral and to the type of weathering agent employed. The calcium borosilicates, Howlite and Bakerite, were weathered most highly by the weathering agents with high calcium‐bonding energies such as amberlite IR‐120 and EDTA. They were moderately weathered by hot water extraction, and weathered least by distilled water. The calcium borate, Colemanite, and the two boron frit compounds released the largest amount of boron when treated with the hydrogen‐saturated IR‐120. The Tourmaline released only traces of boron, regardless of the weathering treatments.The plant root study of the availability of boron revealed the Bakerite mineral as an actively available source of boron, even such that it released excess amounts. The boron held in Tourmaline is unavailable to the plants.
The Availability of Phosphorus in Various Sources of Rock Phosphate as Shown by Greenhouse Studies
Authors: Bennett O. L. , Ensminger L. E. , Pearson R. W. 
Published: July 2010

AbstractGreenhouse studies were carried out to determine the value of seven sources of rock phosphate as compared with superphosphate for production of Sudangrass and Ladino clover on two soils with and without lime. A significant difference was found in the amount of phosphorus available to plants from the various sources of rock phosphate as shown by yields and phosphorus uptake by Sundangrass and Ladino clover. The availability of the seven sources of rock phosphate was affected by both lime and soil type; however, source of rock phosphate was more important than either.In general, the foreign sources of rock phosphate tested, which included Tunis, Morocco, and Curacao Island, were superior to all of the domestic sources of rock phosphate except that of South Carolina. Rock from the latter state was as available as any of the foreign sources of rock phosphate tested.No correlation was found between fluorine content or specific surface of the sources of rock phosphate and their availability to plants. Chemical solubility was a better measure of availability than fluorine content or specific surface.
A Microscopic Method for the Detection of Alkaline Earth Carbonates in Soils
Authors: Matelski R. P. 
Published: July 2010

AbstractA microscopic method for the detection and estimation of alkaline earth carbonates in soils is described. Essentially, the method consists of adding 10.7N sulfuric acid to soil on a glass slide and estimating microscopically the carbonates from the number of needle‐like crystals of calcium or magnesium sulfate that develop. Trace amounts of carbonates can be estimated. The method is also useful in the determination of the relative number of fragments or coatings of carbonates in soils. Data indicate that soils differ in the thickness of the carbonate coating on minerals and in the presence of concretions or rock fragments.
Factors Affecting Calcium Nutrition of Celery, Tomato, and Pepper
Authors: Geraldson C. M. 
Published: July 2010

AbstractAll of the factors most frequently associated with the prevalence and severity of blackheart of celery and blossom‐end rot of tomatoes and peppers can be placed into two categories according to the mechanisms by which they affect calcium nutrition.Mechanism A.—Excessive soluble ammonium, potassium, magnesium, or sodium or a deficiency of soluble calcium (low calcium ratio) cause a decreased calcium uptake and increased incidence of the physiological disorders. On an equivalent basis, ammonium decreases calcium uptake of tomatoes to the greatest degree; sodium the least.Mechanism B.—Excess total salts can cause a calcium deficiency and has frequently been associated with the prevalence of these disorders even when the measurable calcium ratio is considered high or adequate.A deficiency of boron was of minor importance in affecting the calcium nutrition, but high calcium ratios severely accentuated a boron deficiency.A favorable calcium ratio should be maintained to the best degree possible by (1) supplying larger amounts of soluble calcium salts, and (2) avoiding, as much as possible, excesses of soluble ammonium, potassium, magnesium, or sodium salts as well as excess total soluble salts.Periodic calcium sprays are recommended as a source of calcium supplementary to that supplied by the soil as a means of maintaining an adequate supply of calcium to meet the plant requirement at all times.
Genesis of Some Thick‐Surfaced Brunizemic Soils of Eastern Oklahoma
Authors: Brengle K. G. , Gray Fenton , Galloway Harry 
Published: July 2010

AbstractThick‐surfaced Brunizemic soils, Taloka silt loam, occur in eastern Oklahoma and adjoining states. A Taloka silt loam profile consists of (1) a dark grayish brown A1 horizon 10 to 20 inches thick; (2) a brown to light brownish gray, soft floury A2 horizon 10 to 14 inches thick containing some black concretions and slightly mottled in the lower part; (3) a dark grayish brown, mottled B21 horizon with dark clay film on peds, blocky, containing some small black concretions, becoming less dark but more clayey below; and (4) mottled, grayish brown, yellowish brown, and strong brown very firm and very slowly permeable clay (C).The following analyses are reported on (1) each of the several horizons of two profiles of typical Taloka silt loam, and (2) the major horizons of an adjoining Teller fine sandy loam: particle size distribution, bulk density, percent organic matter, percent total nitrogen, and pH. Base‐exchange capacity was determined for the < 2µ fractions of each horizon. Heavy, medium, and light mineral determinations were made on the very fine sand and coarse silt fractions of each horizon.The physical, chemical, and mineralogical measurements indicate that the Taloka silt loams possess more than one solum. The data show that the upper and more silty horizons have undergone horizon differentiation under a different regime of soil development than the more clayey and lower horizons.
Retention of Organic Matter and Nitrogen by the Silt and Clay Fractions and by the Whole Soil as Affected by Lime and Organic Residues
Authors: Laws W. Derby 
Published: July 2010

AbstractThe experiment was conducted in glazed 3‐gallon pots in the greenhouse, using Kirvin clay soil, limed and not limed, treated with red clover, wheat straw, and Juniper wood residues. An application of 59.5 mg. of nitrogen per 100 g. of soil was made at the beginning, and again after 15 months. Soil samples were taken from each treatment before planting the first crop, after 15 months, and again after 48 months. Ten crops were grown during the 4‐year period.There was a marked loss of nitrogen from all soils during the experiment, but loss from limed soil was greater than from unlimed soil. The highly carbonaceous materials retarded nitrogen loss. There was a tendency for nitrogen to accumulate in the silt fraction, especially in unlimed soil.The amount of organic matter retained by the soil was not affected by lime content and there was no difference in organic matter and total nitrogen contents of the wheat straw and red clover treatments after 48 months, although the organic matter/nitrogen ratio was 21.0 for the red clover treatment and 34.4 for the wheat straw treatment when the experiment started.Only the Juniper wood had a significant effect on aggregate stability after 48 months.
Use of Density Gradients for Size Distribution Analysis
Authors: Beavers A. H. 
Published: July 2010

AbstractA linear‐density gradient tube, sensitive to 0.00001 g./ml., was prepared from mixtures of kerosene and bromobenzene and used to measure the specific gravity of small drops of clay and/or soil suspensions.A small drop of suspension (0.005 ml.) was transferred with a micropipette at the required depth from the soil or clay suspension and placed in the density gradient. The drop seeks a level in the tube according to its density which depends upon the concentration of solids. The level is read with a cathetometer and compared to the level of standards of known density and weights.The method is especially suited for the size distribution analysis of material < 0.002 mm. in diameter. Since only 0.005 ml. of suspension is required for a determination, a high‐speed centrifuge that accommodates small tubes can be employed.The density gradient technique is more reproducible than the standard pipette method and lends itself more readily for the size distribution analysis of the clay size materials. It is as accurate for the 0.002‐mm.‐diameter clay and up to the 0.02‐mm.‐diameter silt as the standard pipette analysis, and it requires less time for a determination since only a cathetometer reading is necessary.
Carbon Dioxide from Plant Roots as a Factor in the Replacement of Adsorbed Sodium in Calcareous Soils
Authors: Goertzen J. O. , Bower C. A. 
Published: July 2010

AbstractThe effects of CO2 from plant roots in facilitating the dissolution of CaCO3 and the reclamation of sodic soils was studied by comparing the HCO3‐ concentrations of leachates and the less of adsorbed Na from pots of cropped and uncropped soils receiving uniform leaching with salt‐free water. It was found that the effect of CO2 on the replacement of adsorbed Na was measureable but small, and of less importance than the effect brought about by the hydrolysis of CaCO3 upon leaching. Data were obtained which indicate that alfalfa roots release more CO2 than Rhodesgrass roots, and that more of the CO2 is retained in the soil at high moisture levels than at low moisture levels.
Soils, Paleosols, and Soil‐Horizon Nomenclature
Authors: Ruhe R. V. , Daniels R. B. 
Published: July 2010

AbstractExhumed paleosols commonly occur geographically juxtaposed to modern soils. Use of standard soil‐horizon nomenclature, with its inherent genetic bias, may erroneously portray the histories of the juxtaposed pedo‐geologic soil landscapes. It is suggested that the nomenclature of exchumed paleosols be differentiated from the nomenclature of modern soils by insertion of an upper case P preceding the letter designations of the soil horizons of exhumed paleosols. Application of the proposed nomenclature is illustrated.Lithologic discontinuities of parent materials in which a solum has developed now is designated nomenclaturewise by the use of the subscript u—meaning unconformity. This is a misuse of the term unconformity in the geologic sense. In most cases the superposed parent materials are related conformably rather than unconformably. The vertical sequence of Roman numerals to indicate changes in parent materials, suggested by the Committee on Soil Horizons, adequately handles the problem. Application of the sequence is illustrated.
Variations in Forest‐Derived Soils Formed from Kansas Till in Southern and Southeastern Iowa
Authors: Prill R. C. , Riecken F. F. 
Published: July 2010

AbstractField and laboratory studies were made of forest‐derived Lindley soils formed from Kansan till. Five variants in the present Lindley series were recognized, indicating the wide range in morphological, physical, and chemical characteristics of the series as presently defined. This range was somewhat comparable to the range in properties observed for Gray‐Brown Podzolic soils formed from Wisconsin loess, which range in stage of development from minimal to maximal.The ratio of exchangeable calcium to magnesium did not show a consistent relationship with content of clay in the B2 of the Lindley variants. Neither was there a consistent relationship between content of free iron and clay content in the B2. As several of the Lindley variants have ferretto zones coinciding with the designated B2 layer, the lack of precise relationships between exchangeable cations with clay seems to be related to their burial with loess, and resaturation with bases.There is an apparent relationship of increasing degree of horizon development with decreasing slope for the Lindley variants. However, this is not a simple sequence relationship with topography, as time as well as possibly parent material are also important variables.Evidently the present Lindley series needs to be subdivided into a number of series.
Relationships of Particle and Pore Sizes to the Growth of Sunflowers
Authors: Miller Scott A. , Mazurak A. P. 
Published: July 2010

AbstractSunflowers (Helianthus annuus, L.) were grown in 20 compacted soil separates, ranging in diameters from 4,760 to 2.31µ, which contained pores of diameters between 529 to 2.23µ. Two moisture levels, 20‐cm. water tension and moisture content at “flex point,” were imposed on the 20 separates. Nutrient solution was applied to the separates.Noticeably different growth rates of sunflowers were measured at the two moisture levels. Maximum rate of stem elongation at 20‐cm. water tension was nearly three‐fold greater than was that at “flex point” moisture percentage. Maximum growth of sunflowers at 20‐cm. water tension was obtained from separates between 52.3 and 210µ in diameter or pores with mean diameters of 17.7 to 43.5µ. Optimum growth of sunflowers at “flex point” moisture was on separates 13.1 to 9.25µ in diameter whose pores were about 4µ in diameter. Aeration appeared to limit the rate of stem elongation when air occupied less than 4% of the pore space.Maximum growth rate of sunflowers at both moisture levels apparently was determined by the influence of pore size upon aeration and area of root‐solution contact. The greater the area of root‐solution contact, as determined by pore size and moisture tension, the more favorable was the growth of roots and shoots, provided aeration was not limiting.
Some Tests of the Similar Media Concept of Capillary Flow: I. Reduced Capillary Conductivity and Moisture Characteristic Data
Authors: Klute A. , Wilkinson G. E. 
Published: July 2010

AbstractPlainfield sand was dry‐sieved into the following five size fractions: 104 to 125, 125 to 149, 149 to 177, 177 to 210, and 210 to 250µ. The bulk densities of the sand fractions, when packed in a standard manner, averaged 1.65 ± 0.01 g. per cc. The particle densities of the fractions averaged 2.61 ± 0.01 g. per cc. The size distribution of each fraction was determined microscopically. The bulk density, particle density, and the reduced size‐distribution curves indicated that the sand fractions could be considered similar media.Capillary conductivity as a function of the moisture tension was determined. When the reduced conductivity was plotted against the reduced tension, the data coalesced into one curve within the limits of experimental error. Moisture characteristic curves of the sand fractions also coalesced into one curve when the reduced tension was plotted against the volume moisture content. The results of this study seem to support the similar media concept.
Inositol Hexaphosphate: III. Content in Soils
Authors: Caldwell A. G. , Black C. A. 
Published: July 2010

AbstractSamples of 49 soils were analyzed for inositol‐hexaphosphate phosphorus in the meso form and a supposed isomer of this form. Anion‐exchange chromatography was used to make the separations. The quantities of phosphorus present in the two isomers were correlated (r = 0.73), the phosphorus in the supposed isomer averaging 46% of that in the meso form. The total inositol‐hexaphosphate phosphorus averaged 39γ per g. of soil and made up an average of 17% of the total organic phosphorus with a range from 3 to 52%. Of the factors examined, the content of organic phosphorus in forms other than inositol hexaphosphate provided the best prediction of inositol‐hexaphosphate phosphorus. After the quantities of this noninositol‐hexaphosphate organic phosphorus had been taken into account, the soil pH and content of free iron oxide were not of significant independent value in predicting the content of inositol‐hexaphosphate phosphorus. The percentage content of inositol‐hexaphosphate phosphorus in the organic phosphorus was higher in soils developed under forest vegetation (24%) than under grassland vegetation (14%) and decreased with increasing pH in both types of soils. The ratio of inositol‐hexaphosphate phosphorus to other forms of organic phosphorus averaged the same in samples of 10 cultivated soils as in samples of the corresponding virgin soils, thus indicating that the inositol‐hexaphosphate phosphorus decomposed at about the same rate as the other forms of organic phosphorus.
Temperature‐Time Curves as Soil Freezes Related to Moisture‐Stress Curves
Authors: Evans D. D. , Horrigan J. A. , Chinn C. E. 
Published: July 2010

AbstractThe rate of cooling of a moist soil sample during freezing is determined by the rate of heat dissipation to the surroundings and the rate of ice formation with the sample. Assuming equilibrium conditions at an instantaneous temperature, the amount of ice formed between two temperatures depends upon the amount of water held in the sample between the soil moisture stresses associated with the two temperatures.Temperature‐time curves (freezing curves) during freezing have been obtained for soils using a thermistor and recording potentiometer. The curves have been related to moisture‐stress curves derived through the use of standard pressure apparatus. A method is presented which may allow the construction of a moisture‐stress curve from one freezing of a single sample of soil.