bluuebunny/crossref_metadata_2025_split huggingface dataset:
Greenhouse Evaluation of Residual Phosphate by Four Phosphorus Methods in Neutral and Calcareous Soils
Authors: Bowman R. A. , Olsen S. R. , Watanabe F. S. 
Published: July 2010

AbstractFour determinations of phosphorus—Olsen‐P, Colwell‐P, total exchangeable P, and resin‐extractable P—were evaluated in terms of total plant P uptake in a 3‐year continuous greenhouse study of 23 high P calcareous and neutral soils. All methods were highly correlated with the total P taken up from the soils by 5–8 successive greenhouse crops. The Olsen‐P procedure extracted an average of nearly 50% of the total plant P while the Colwell procedure extracted nearly 80%. Resin‐extractable P and total exchangeable P values approximated the total plant P uptake, and served as good biological measures of the total plant‐available P in the soil. No significant differences were observed between the carrier and carrier‐free 32P methods on the 23 test soils.
Straw‐mulch Rate Effect on Soil Water Storage and Sorghum Yield
Authors: Unger Paul W. 
Published: July 2010

AbstractA field study was conducted to determine the effects of straw mulch rates on soil water storage during fallow and on subsequent grain sorghum [Sorghum bicolor (L.) Moench] production. Wheat [Triticum aestivum (L.)] straw at rates of 0 (check), 1, 2, 4, 8, or 12 metric tons/ha was placed on field plots in July 1973, 1974, and 1975. A different area, previously cropped to dryland wheat, was used each year. Atrazine [2‐chloro‐4(ethylamino)‐6‐(isopropylamino)‐s‐triazine] was applied for volunteer wheat and weed control before mulch placement. Soil water content was measured periodically from July until the following May, when grain sorghum was planted, and during the sorghum growing season. Available soil water at planting averaged 12.3 and 21.4 cm for the 0‐ and 12‐metric tons/ha mulch treatments, respectively. The additional water, along with greater infiltration and lower evaporation during the growing season, increased grain yields, which averaged 1,780 and 3,990 kg/ha for the respective treatments. Water‐use efficiency increased from 55.6 kg/ha‐cm for no mulch to 115.0 kg/ha‐cm for 12 metric tons mulch/ha.
A Soil‐Water‐Nitrogen Model for Irrigated Corn on Sandy Soils
Authors: Watts D. G. , Hanks R. J. 
Published: July 2010

AbstractA model was developed which describes the net changes of nitrogen amounts due to transformations and the movement, uptake, and loss of nitrogen from the root system of irrigated corn (Zea mays L.) grown on sandy soils. A potential nitrogen uptake function developed from field data is used to determine the maximum uptake for nonlimiting soil water and nitrogen availability. Actual uptake is calculated as less than potential when soil water content and/or mineral nitrogen concentration and distribution limit convective and diffusive movement of nitrate to the root system. Separate calculations are made for uptake resulting from each of these two mechanisms. Seasonal nitrogen uptake was computed within ± 15% of measured uptake on field plots where uptake by above ground plant material ranged from 105 to 218 kg/ha. Computed nitrate leaching losses compared favorably with losses estimated by multiplying percolation loss determined from a weekly water balance, by measured nitrate concentration at 150 cm depth. Field leaching losses estimated by the water balance‐concentration method ranged from 37 to 154 kg/ha.
Alterations of Micas and Feldspars During Microbial Formation of Basic Ferric Sulfates in the Laboratory
Authors: Ivarson K.C. , Ross G.J. , Miles N.M. 
Published: July 2010

AbstractDuring the oxidation of ferrous iron in solution by the iron‐oxidizing bacterium, Thiobacillus ferrooxidans, formation of jarosite [KFe3(SO4)2(OH)6] occurred in the presence of glauconite, illite and microcline whereas natrojarosite [NaFe3(SO4)2(OH)6] was formed in the presence of albite. The required K and Na were supplied by these minerals and considerable amounts (up to 12%) of jarosite were formed during four months of reaction. When NH4 ions were present in solution, K release from the minerals appeared to be blocked and ammoniojarosite [NH4Fe3(SO4)2(OH)6] was formed. In the absence of NH4 ions or K‐ and Na‐bearing minerals an amorphous precipitate formed. X‐ray diffraction and chemical data indicate that interlayer K was preferentially removed from glauconite which resulted in an expanding phase having a d(001) spacing of 18Å with Mg and glycerol saturation. There was little preferential removal of interlayer K from illite as most of the K was removed by approximately stoichiometric dissolution. The K from microcline and the Na from albite were also removed stoichiometrically during jarosite and natrojarosite formation. The K released for jarosite formation followed the order glauconite>illite>microcline. The availability of Na from albite was somewhat greater than the availability of K from microcline.The results show that in acid sulfate soils where ferrous iron, Thiobaccillus ferrooxidans and basic ferric sulfates are abundant, clay minerals can supply the alkali cations for the formation of these sulfates.
Prediction of Phosphorus Diffusion from Fertilizer Source
Authors: Hira G. S. , Singh N. T. 
Published: July 2010

AbstractRate of P diffusion from fertilizer applied at the soil surface was studied using Fick's law of diffusion. The diffusion coefficient of P was determined from a knowledge of the tortuosity factor and P adsorption isotherm. Phosphorus diffusion coefficient calculated from Nye's equation did not prove suitable at very low or high concentration of P at the soil surface. The phosphorus diffusion coefficient calculated from experimental data increased linearly with the square root of P concentration applied at the source. Phosphorus diffusion coefficient could be calculated from the equation,
urn:x-wiley:03615995:saj2sssaj197803615995004200040005x:equation:saj2sssaj197803615995004200040005x-math-0001 Predicted P concentration‐distance profiles were very close to the experimental values estimated by employing a sectioning technique.
Phosphate Desorption from Kaolinite Suspensions
Authors: Bar‐Yosef B. , Kafkafi U. 
Published: July 2010

AbstractPhosphate desorption from soil minerals is one of the factors which determine the rate of P uptake by plants. Under laboratory conditions desorption is usually obtained by drastic dilution or leaching of the clay, thus inducing its dissolution. The objective of this work was to study the effect of the desorption method used, equilibration time and the dissolved silica on the desorption of P from kaolinite. Two desorption methods were used: (i) diluting 1% suspensions by various volumes of the same electrolyte, and (ii) immersing a dialysis tube containing 0.25% suspension (+P) in an identical suspension initially free of P. The desorption process in both cases could be divided into a rapid and a slow first‐order reaction. The rapid reaction rate constant was similar in both systems (about 4.65 × 10−3hours−1 at 25°C). The slow reaction constants were 0.3 × 10−3hours−1 and 1.15 × 10−3hours−1 for cases (i) and (ii), respectively. The activation energy of the desorption process in case (ii) was 16.2 Kcal/mole for the rapid and 4.8 Kcal/mole for the slow reaction. The amount of silica dissolved from kaolinite due to dilution with 0.01M KCl depended on the dilution ratio and reached 16 mg SiO2/g kaolinite when the suspension was diluted 100‐fold. Readsorption of part of the dissolved silica is stipulated to contribute to the fast P desorption process.
Use of K/Rb Ratio to Characterize Potassium Uptake by Plant Roots Growing in Soil
Authors: Baligar V. C. , Barber S. A. 
Published: July 2010

AbstractInteraction between the plant root and the soil on cation influx into the root is not well understood. Use of the ratio of K/Rb, two ions absorbed interchangeably by the root, enables measurement of the K ion medium influencing K flux into the root. In experiments with corn (Zea mays L.) grown in eight soil‐K systems in a growth chamber, the K/Rb ratio of uptake was similar to the K/Rb ratio of the ions on the exchange sites, and not the K/Rb ratio of the solution cations. The data may be interpreted to indicate that K and Rb on the exchange sites had more influence on K and Rb flux into the root than K and Rb in solution. Diffusion of K and Rb from the soil to H‐saturated exchange membranes was in the ratio of K/Rb in solution.
Factors Affecting Denitrification in a Sonoran Desert Soil
Authors: Westerman R. L. , Tucker T. C. 
Published: July 2010

AbstractIncubation studies were conducted to determine the effect of temperature, moisture content, organic C, soil depth, and time on transformations of added 15NO3‐N to a Sonoran Desert soil in open and closed systems. In open system studies, increasing temperature from 20° to 37°C, adding organic C, and increasing moisture content from field capacity to saturation increased denitrification losses 16, 22, and 2%, respectively. There were no apparent differences in immobilization of 15NO3‐N due to temperature, time, moisture content, or soil depth without organic C amendments. However, immobilization of 15NO3‐N soils with organic C amendments was increased markedly with increased temperature and time, but initial moisture content had little effect. At C/N ratios of 150:1 only traces of 15N appeared in NH4‐N, however, at C/N ratios of 15:1 to 45:1 ammonification and immobilization occurred simultaneously.Closed system investigations with organic C and 15NO3‐N amendments showed 79% loss in 5 days with the remaining 21% accumulating as organic‐15N. Denitrification losses in open systems with soil moisture contents representative of saturated conditions were 70% of the loss observed under closed systems at the same moisture content.
Potassium Uptake by Onion Roots Characterized by Potassium/Rubidium Ratio
Authors: Baligar V. C. , Barber S. A. 
Published: July 2010

AbstractA common belief is that plant roots absorb cations from the solution phase of the soil. Experiments with corn (Zea mays L.) using K/Rb ratio to evaluate the source of K and Rb absorbed indicated the plant roots absorbed these ions in the ratio of exchangeable K and Rb. The objective of this research was to study the source of K and Rb absorbed from soil by onion (Allium cepa) roots since they do not have root hairs and this may influence the uptake mechanism. Onions absorbed K/Rb with a ratio which was intermediate between the ratio of exchangeable K and Rb and the ratio of these cations in solution. In comparison with corn, onions absorbed K at one‐third the rate, but absorbed water three times faster so that mass flow contributed a greater proportion of K absorbed by onions than that by corn. This, rather than differences in root hairs may be the reason for the observed differences in K uptake between corn and onions.
Salt Outflows from New and Old Irrigated Lands
Authors: Carter D. L. , Robbins C. W. 
Published: July 2010

AbstractThree water application treatments with low salt water were applied to previously nonirrigated soil and to a similar soil which had been irrigated for 67 years. The total soluble salt content of these soils initially, and after one and two seasons of treatment, was measured to determine salt outflow. Residual soluble salts were essentially removed from the previously nonirrigated soil after 30 cm of water/m depth of soil had passed from the soil as leachate, regardless of the number of seasons required for that amount of leaching. The total quantity of residual salt removed from soil 5 m deep was 70 metric tons/ha, with about 38 metric tons/ha being leached out by the first 14 cm of leachate. After the residual salt was removed, the salt content of the newly irrigated soil was the same as that of the soil which had been irrigated for 67 years. Subsequent salt outflow from the soil was directly related to the quantity of water leaching through the soil, indicating that more minerals dissolved with more leaching. Soils irrigated for many years and then not irrigated for up to 10 years had no measurable reaccumulation of soluble salts during the period of nonirrigation. Results of these investigations provide a basis for estimating salt outflows from newly developed and old irrigated lands, and for assessing the impact of these salts on surface and groundwater supplies.
A Soil Moisture Budget Model Accounting for Shallow Water Table Influences
Authors: Stuff R. G. , Dale R. F. 
Published: July 2010

AbstractSoil moisture balance programs developed on well‐drained soils were found to be unsatisfactory for a soil underlain by shallow water tables, a condition typical of about 9 million acres of cropland in Indiana. Capillary rise past a 105‐cm root zone boundary was estimated as the difference between estimated evapotranspiration (ET) and changes in soil moisture under corn (Zea mays L.) on a tile‐drained Typic Argiaquoll at West Lafayette, Ind. during three growing seasons, 1971–1973. Capillary water was found to supply an average of 27% of the ET in periods with little or no precipitation. Computer model estimates showed capillary water to furnish about 17% of the total ET over a 100‐day period from 49 days before silking to 50 days after.Evapotranspiration was based on measured pan evaporation adjusted with crop development and moisture stress factors from the literature. Soil moisture in the root zone was measured by neutron counting and expressed as deficits from a variable holding capacity which was allowed to change in time depending upon the depth of the shallow water table. Water table levels were measured in open wells, and water table changes were statistically related to the estimated amounts of capillary rise for use in the model. The factors used to estimate capillary rise were the soil moisture deficit in the root zone and depth of the water table.The derived relationships with those obtained from literature sources and assumptions regarding runoff and recharge were programmed in a computer model for simulating the daily moisture status and changes in the corn root zone. Model inputs were pan evaporation, precipitation, soil moisture characteristics, corn silking date, and initial soil moisture conditions. The model was found to closely track measurements of both soil moisture and water table depths in four independent seasons: early and late plantings in 1970 and 1974.
Coupling Phenomena in Saturated Homo‐ionic Montmorillonite: III. Analysis
Authors: Groenevelt P. H. , Elrick D. E. , Blom T. J. M. 
Published: July 2010

AbstractThe data presented in the first paper of this series are analyzed using the theoretical transport equations and the analytical expressions for the transport coefficients developed in the second paper of the series.When the electrodes of the system presented in Part 1 of this series are not shorted the predicted behavior corresponds precisely with the actual behavior.Upon shorting the electrodes, the data indicate that the actual shorting of the clay‐water system is not perfect, an indication that the electrodes cannot release and absorb Cl‐ ions infinitely fast. From the data the shorting efficiency is calculated. The flux of cations through the clay‐water system while the electrodes are shorted can then be calculated. The absolute value of this flux appears to be slightly larger than the value calculated from the decrease in time of the salt concentration difference in the two liquid compartments. This is likely due to the buildup of a salt concentration gradient in the membranes.
Solute Travel‐time Estimates for Tile‐drained Fields: III. Removal of a Geothermal Brine Spill from Soil by Leaching
Authors: Jury W. A. , Weeks L. V. 
Published: July 2010

AbstractThe time required to leach a slug of saline, sodic geothermal brine from the point of injection to the tile outlet of an artificially drained field is calculated. Sprinkler, complete, and partial ponding leaching methods are compared as a function of drain spacing and initial location of the spill. Calculated results are presented as dimensionless parameters which scale the drainage system dimensions and the soil water transport properties. Ponded leaching required more water, but less time to leach brine out of the system for all situations except where the brine spill occurs near the midpoint between tile lines.A simple calculation is proposed to estimate the leaching fluid volume required to remove excess Na+ from the exchange complex. Good agreement was attained between simulated and experimental results involving a laboratory soil column. For fine‐textured soils in the Imperial Valley of California it may require up to 30 pore volumes of leaching fluid to replace Na+ with Ca2+ if saturated gypsum solution is used in reclamation. Application time per pore volume was calculated to be in excess of 1 year for all cases except ponded leaching directly over a tile line.
A Mathematical Treatment of Infiltration from a Line Source into an Inclined Porous Medium
Authors: Zachmann D. W. 
Published: July 2010

AbstractAn exact mathematical solution is obtained for two‐dimensional steady infiltration from a line source into an inclined porous medium with an impermeable lower boundary. Unsaturated hydraulic conductivity is assumed to be an exponential function of pressure head. Equations for a stream function and the pressure head are developed and stream lines and contours of constant pressure head are plotted for a sandy soil and a clay soil using inclinations of 5° and 20° from horizontal.
The Spectrophotometric and Fluorometric Determination of Aluminum with 8‐Hydroxyquinoline and Butyl Acetate Extraction
Authors: Bloom P. R. , Weaver R. M. , McBride M. B. 
Published: July 2010

AbstractA spectrophotometric method and a fluorometric method for the determination of Al by the extraction of the Al‐hydroxyquinolate complex with butyl acetate were evaluated. The Al complex was found to be very stable in butyl acetate. Since butyl acetate is less dense than water the extractions could be done in screw top tubes and it was not necessary to dewater the solvent phase.The spectrophotometric method was found to be useful for the analysis of solutions containing 2 × 10−6M (50 ppb) Al or greater. The spectrophotometric response was linear up to absorbance = 1.1. The relative error in midrange was < 2.5%. The quantity of Al determined in soil extracts was shown for some soils to be strongly dependent on the time of contact with the complexing reagents before extraction with butyl acetate. This was attributed to the complexation of Al by organic matter in the soil solutions.The flourometric method was found to have a detection limit of about 1 × 10−8M (0.3 ppb) Al. The fluorometric response was nearly linear in the most sensitive range of the fluorometer but was less linear for higher Al concentrations. The relative error was < 8% except near the detection limit.There was no interference with either method from Na+, K+, Mg2+, Ca2+, Sr2+, Ba2+, Fe2+, Fe3+, F‐, PO43‐, SO42‐, and SiO32‐ at the levels found in most soil extracts.
Adsorption and Extractability of Molybdenum in Relation to Some Chemical Properties of Soil
Authors: Karimian N. , Cox F. R. 
Published: July 2010

AbstractDevelopment of a practical soil test for molybdenum (Mo) will depend on selection of the proper extractant. To achieve this, more knowledge is needed about Mo adsorption and its extractability, especially in relation to other soil properties.Adsorption of Mo from aqueous solutions was determined for eight soils from the Atlantic Coastal Plain and Piedmont regions. The data followed the Freundlich isotherm more consistently than the Langmuir. Adsorption increased as the organic matter and/or Fe oxide contents of the soils increased. Adsorption from an aqueous solution that was initially 0.3 mM Mo (AdMo) also was determined on 32 soils collected from the regions. The AdMo level was positively correlated with Fe oxide and organic matter contents and negatively correlated with pH and P levels.The level of Mo extracted with acid ammonium oxalate (Grigg Mo) and an anion exchange resin (resin Mo) were also determined and related to soil chemical properties and a lime treatment. Grigg Mo was positively correlated with amorphous and free Fe oxide contents, probably as a result of the strong dissolution of Fe oxide by oxalate. Resin Mo was positively correlated with pH but not with other soil properties. Incubating soils with CaCO3 increased the level of resin Mo.
Genetic Association of Properties of Soils of an Area in the Upper Amazon Basin of Peru
Authors: Tyler E. J. , Buol S. W. , Sanchez P. A. 
Published: July 2010

AbstractSoil properties of a 400‐ha area in the Upper Amazon Basin of Peru were found to be related to the nature of the parent material and to occurrence of defined geomorphic surfaces. The soils are developed from unconsolidated sandy to clay textured river sediments, originating in the Andes Mountains. The oldest surface is presently on the level hill tops. A surface which cuts the higher older surface and grades to the intervening valley floors of the same age and the recent flood plain is the youngest geomorphic surface.The Typic and Aquic Paleudults of the oldest surface generally have lower pH values, lower base saturation, and contain less weatherable minerals, but contain greater amounts of clay‐sized kaolinite than the soils of the younger surface. The soils of the erosional surface are Ultisols, Inceptisols or Alfisols. Genetic control of these soils appears to depend upon the location of an impervious layer which controls ground water depth. The Alfisols, Inceptisols, and Entisols of the flood plain contain about 15% weatherable minerals and high amounts of well crystalized smectite clay minerals that have probably undergone limited pedologic alteration.
Clay Minerals of Montana Soils Formed on Volcanic Parent Materials
Authors: Klages M. G. 
Published: July 2010

AbstractSamples were taken of soils formed on volcanic materials varying in age from Cretaceous to Recent. The soil samples were analyzed for particle size distribution, pH, organic matter, cation exchange capacity, and exchangeable cations. Clays were separated and identified by X‐ray diffraction supported by chemical analysis. Clay mineralogy varied with age of the parent material. Recent ash in western Montana from sources in Washington and Oregon gave rise to amorphous clays in eight of nine samples. Soils on Quaternary volcanics near Yellowstone National Park had amorphous or poorly crystalline 2:1 clays. Clays of soils from Tertiary age volcanics were dominated by smectite. Cretaceous volcanics gave rise to mixed 2:1 clays similar to soils on Cretaceous sediments in the Northern Great Plains. Exchangeable cations in the soils varied with the dominant clay minerals.