bluuebunny/crossref_metadata_2025_split huggingface dataset:
Linearized Moisture Flow with Loss at the Soil Surface
Authors: Lomen D. O. , Warrick A. W. 
Published: July 2010

AbstractThe general solution of a linearized moisture flow equation is derived for point and line sources whether buried or on the soil surface. The surface flux is taken to be proportional to the matric flux potential, which is consistent with the physical situation of small evaporative losses for dry soil and larger losses for wet soil. The fraction of water lost at the surface turns out to be identical for point and line sources and for the steady‐state case is [m/(2 + m)] exp(−ad) where m is the surface flux proportionality constant, d the depth of source, and α a constant from the assumed unsaturated hydraulic conductivity function. This fraction is plotted as a function of time for a fixed source depth. Also given are curves depicting the total water loss as a function of source depth. A generalized solution is derived for any type of source located in a horizontal plane.
Sorption and Availability of Molybdenum in Soils of Western Oregon
Authors: Jarrell W. M. , Dawson M. D. 
Published: July 2010

AbstractEight western Oregon soils were chemically characterized in an attempt to identify soil parameters affecting residual availability of fertilizer Mo to subterranean clover (Trifolium subterraneum L.). Amounts of “exchangeable” Fe and Al, “amorphous” Fe and Al, and “crystalline + amorphous” Fe in the soil were determined. As a measure of surface colloid OH‐ reactivity, the meq of H+ required to maintain a mixture of H2O2‐treated soil and 0.85N NaF at pH 6.8 was measured over a 25‐min period. Anion‐exchange‐resin‐extractable Mo (AER Mo) was removed from soil with a strongly basic anion exchange resin.Molybdenum adsorption isotherms for each soil were determined by equilibrating soil samples at 25°C with Mo solutions ranging in concentration from 2 to 20 mg Mo/liter. The data for each soil conform to a Freundlich adsorption isotherm specific for that soil.Molybdenum adsorption was related to the (NH4)2C2O4‐extractable Fe in the soil (R2 = 0.85**), but not to other fractions of extractable Fe or to extractable Al forms. The OH‐ released from each soil after 2 min of NaF treatment was correlated with NH4OAc‐extractable Al(R2 = 0.65**). Molybdenum uptake by subterranean clover grown in field experiments was significantly correlated with AER Mo (R2 = 0.17*). The correlation was significantly improved when two soils which behaved differently from the rest were statistically analyzed separately; the resulting correlations for the groups of two and six soils were R2 = 0.64** and R2 = 0.72**, respectively.
Effects of Solution Chemistry and Environmental Conditions on Ammonia Volatilization Losses From Aqueous Systems
Authors: Vlek P.L.G. , Stumpe J. M. 
Published: July 2010

AbstractLaboratory studies were conducted to explain the wide variation in reported estimates of ammonia volatilization losses from N‐fertilized paddy fields. The ammonia volatilization capacity of a system was found to be equivalent to its alkalinity [NH3(aq), HCO32‐]. In solutions lacking alkalinity, loss of (NH4)2SO4 was limited, whereas loss of (NH4)2CO3 was essentially complete.Ammonia loss from solution is best described as a consecutive reaction with opposing step. Ammonia volatilization per se followed first‐order reaction kinetics. The rate of ammonia volatilization is thus directly related to the concentration of aqueous ammonia and therefore to the concentration of ammoniacal N and pH. The rate of ammonia volatilization was severely restricted by limiting the movement of air above the water, as is often the case in the laboratory and field studies reported to date. Ammonia volatilization was enhanced by water turbulence and increased exponentially with temperature from almost nil at 0°C to approximately 20 mg N/100 cm2/5 hours at 46°C.
A Two‐Element Ceramic Sensor for Matric Potential and Salinity Measurements
Authors: Scholl David G. 
Published: July 2010

AbstractA two‐element ceramic sensor was developed to produce optimum electrical response both to soil water matric potential and salinity. A spring‐loaded housing was developed for the elements for either drill‐hole or pit‐face placement. The sensors were calibrated under various matric potential, salinity, and temperature conditions. An initial field test with 72 sensors was conducted under irrigated coal mine spoil conditions. Laboratory and field results indicated reasonable instrument precision over a wide range of matric potential and salinity. The correlation between sensor output and water content in the field was best where the mean of several sensors was used.
The Use of Zero Point of Charge (ZPC) to Assess Pedogenic Development
Authors: Hendershot W. H. , Lavkulich L. M. 
Published: July 2010

AbstractThe pH at the zero point of charge (ZPC) has been used to characterize the electrochemical properties of soils. To date, most studies have focussed on soils high in oxides with low phyllosilicate content. The study reported here attempts to use ZPC determinations to characterize the surface charge characteristics of soils from a temperate region. Three soils were examined; these ranged in pedogenic development, as expressed by soil morphology, from a small accumulation of sesquioxides to a relatively high one. The soils were a Dystric Eutrochrept, a Typic Ferrudalf, and a Spodic Ferrudalf. With increased pedogenic development the ZPC became more clearly defined and approached the natural pH of the soil, and there was a decrease in the relative significance of the pH‐independent charge. The ZPC may be used as a measure of pedogenic development.
Nitrogen Sources for Hay Production on Flooded Meadows
Authors: Ludwick A. E. , Rumburg C. B. , Siemer E. G. 
Published: July 2010

AbstractThree experiments were conducted over a 3‐year period to compare various urea materials and ammonium nitrate as N sources for hay production on flooded meadow sites. Each experiment was a complete factorial combination of fertilizer N sources and rates broadcast once in the spring on established forage prior to flood irrigation. Experiment 1 in Gunnison County consisted of ammonium nitrate (AN), urea (U), sulfur‐coated urea (SCU), and urea ammonium polyphosphate (UAPP) broadcast at rates of 0, 67, 134, 202, and 269 kg N/ha. A second season's data was collected to evaluate carryover N. Experiments 2 and 3 were conducted in Jackson County for a single season and consisted of AN, U, UAPP, and urea ammonium sulfate (UAS) broadcast at 0, 90, 179, and 269 kg N/ha.Hay yields and N uptake were significantly increased by N fertilizer at each location; there was no significant response in hay yield or N uptake resulting from residual N in the second season of Experiment 1. Source of N did not influence hay yields nor N uptake. The N content of the hay was significantly influenced by the N fertilizer rate at two locations and the N source at one location. In general, hay yields and N uptake increased with increasing rates of fertilizer N. Fertilizer efficiency was low at all locations, ranging between 8.5 and 19.6 kg hay/kg N. Fertilizer N recovery was <30% for all treatments. Both efficiency and recovery of N tended to decrease with increasing N rates.
Calcium‐supplying Characteristics of Two Gypsum Materials on Southeastern Coastal Plain Soils
Authors: Keisling Terry C. , Walker Milton E. 
Published: July 2010

AbstractField studies were conducted on two soils to study the manner in which finely and coarsely divided gypsum materials supplied Ca to the soil depth where peanut (Arachis hypogaea L.) fruit absorb Ca. The finely divided material was characterized chemically as CaSO4 · 2H2O, approximately 72% CaSO4 or 20.2% Ca and physically as having 88% of the particles < 0.25 mm in diameter. The coarsely divided material was characterized chemically as CaSO4, approximately 92% CaSO4 or 26.5% Ca and physically as having 82% with particle diameters < 4.2 mm, but > 0.5mm. Each material was applied at three rates in randomized complete block experiments. At approximately 3‐week intervals, composite soil samples were collected at the 0‐ to 5‐, 5‐ to 10‐, and 10‐ to 15‐cm depths and extracted with acid (0.05N HCl + 0.025N H2SO4) extractant which was analyzed for Ca.The amount of Ca transported to a given soil depth was found to be related to the magnitude, order, and frequency of rainfall events. Generally, several small rainfall events resulted in accumulation of Ca near the soil surface, whereas, larger rainfall events resulted in a reduced Ca concentration near the soil surface for both materials. The fine gypsum material was found to be more effective in supplying Ca to the soil depth where peanut fruit are absorbing it early in the growing season than the coarser material.Dissolution of gypsum sources consisting of different particle sizes and subsequent transport of Ca into the fruiting zone of peanuts was not always closely related to the total amount of rainfall. Either the finely or coarsely divided gypsum could supply more Ca to the fruiting zone depending on the rainfall pattern.
Thermodynamics of Potassium‐Calcium and Magnesium‐Calcium Exchange Reactions on a Kaolinitic Soil Clay
Authors: Udo E. J. 
Published: July 2010

AbstractThermodynamic parameters derived from experimental results were determined for the potassium‐calcium and magnesium‐calcium exchange reactions on a kaolinitic soil clay separated from the B horizon of a strongly weathered soil profile. The clay samples were equilibrated at 10° and 30°C with a mixed solution of KCl and CaCl2 for the K‐Ca system or MgCl2 and CaCl2 for the Mg‐Ca system. For the K‐Ca system, the selectivity coefficients were high indicating a greater affinity of the clay for K than for Ca. The high equilibrium constant and the negative values of standard free energy and enthalpy changes for the exchange of Ca for K also revealed a preference of the clay for K relative to Ca ions.In the Mg‐Ca system, the exchange isotherms and the low selectivity coefficients indicated a preference of Ca ions for the clay phase. This exchange of Ca for Mg was accompanied by an increase in the free energy and enthalpy changes also pointing to a more stable Ca‐clay than Mg‐clay.
Surface Charge Manipulation of Constant Surface Potential Soil Colloids: I. Relation to Sorbed Phosphorus
Authors: Wann S. S. , Uehara G. 
Published: July 2010

AbstractA significant correlation was found between the zero point of charge and the quantity of phosphorus applied to soil material from an Oxisol. Sorbed phosphorus lowered the zero point of charge and increased surface charge density at any pH above the zero point of charge. The soil was treated with 0, 100, 500, and 1,500 ppm P as (NH4)2HPO4. For the soil with no added phosphorus, low concentration of monovalent electrolyte and within two pH units of the zero point of charge, diffuse layer theory adequately predicted surface charge. For high electrolyte concentration and high pH, the Stern theory with specific adsorption energy predicted the experimental results. The calculated results indicated charge reversal in the high‐phosphorus samples.
Transient Changes in the Soil‐water System from Irrigation with Saline Water: II. Analysis of Experimental Data
Authors: Jury W. A. , Frenkel H. , Devitt D. , Stolzy L. H. 
Published: July 2010

AbstractTwenty‐three lysimeters containing four soil types with alternate wheat (Triticum aestivum L.) and sorghum (Sorghum vulgare Pers.) crops were irrigated with three synthesized levels (2.2, 3.9, 7.1 mmho/cm) of irrigation water. Salt balance was calculated from soil salinity sensor electrical conductivity EC measurements by determining a relationship between solution EC and solution concentration using a chemical equilibrium model. Solution samples and saturation extracts were taken to determine ion balances, and exchangeable cations were measured after the third crop.All methods of determining salt balance showed the order of 50% salt precipitation over the first 500 days of the experiment, approximately two times the expected amount when root zone salt concentrations have reached steady state. Release of Ca2+ ions from exchange sites and subsequent enhanced gypsum and CaCO3 precipitation was assumed to be responsible for the difference between transient and steady‐state behavior.The drainage composition of a lysimeter which had moved one pore volume through the root zone showed that only Cl‐ was approaching a steady‐state value. Exchange effects and enhanced precipitation were assumed to be buffering the concentration of the other ions.Water uptake in all lysimeters is occurring primarily in the top 20 cm, a consequence of high irrigation water salinity and daily irrigation.
Calcium Ion Complexation by Fulvic Acid Extracted from Sewage Sludge‐soil Mixtures
Authors: Sposito Garrison , Holtzclaw Kenneth M. , LeVesque‐Madore C. S. 
Published: July 2010

AbstractThe complexes formed between Ca2+ and fulvic acid extracted from sewage sludge were investigated by potentiometric titration of K/H‐fulvate with Ca(NO3)2 at pH 7 and 25°C, in an ionic medium of 0.1N KNO3. Formation functions, giving the number of moles of Ca bound per mole of K/H‐fulvate, were calculated from the titration data and plotted against the concentration of Ca2+, with the concentration of K/H‐fulvate being a fixed parameter for each plot. The molarity of K/H‐fulvate, which was held rigorously constant during each titration, was determined with the help of separate experiments in which the number‐average molecular weight of the K/H‐fulvate sample employed was measured by vapor pressure osmometry. The formation functions were interpreted as evidence of: (i) a relatively strong ion pair that is formed between Ca2+ and the most acidic functional groups in fulvic acid, and (ii) a weaker ion pair that is formed between Ca2+ and the more weakly acidic functional groups. The properties of the latter complex depend both on pH and on the concentration of fulvic acid, since these variables in part determine the number of ionized, weakly acidic functional groups that can react with Ca2+. The Ca2+ ion was shown to have a modest ability to displace protons from undissociated acidic functional groups in sludge‐derived fulvic acid.
The Acetylene Inhibition Method for Short‐term Measurement of Soil Denitrification and its Evaluation Using Nitrogen‐13
Authors: Smith M. Scott , Firestone Mary K. , Tiedje James M. 
Published: July 2010

AbstractAcetylene was found to effectively inhibit the reduction of N2O by anaerobic soils. With concentrations of C2H2 above 0.1 atm, added NO3‐ was quantitatively converted to N2O, and added N2O was reduced at an insignificant rate. Experiments with 13N demonstrated that at low soil nitrate concentrations at least 0.1 atm C2H2 was required for effective inhibition. Denitrification rates determined by 13N and by C2H2 inhibition methods correlated well, as did determinations of N2O/(N2 + N2O). The methods also revealed that an acceleration in denitrification rate occurred within a few hours after soil was exposed to anaerobic conditions. The acetylene method was generally used to measure denitrification rates in soils incubated as anaerobic slurries, but was also used to determine rates for field moist aggregrates incubated anaerobically and aerobically. When assayed as anaerobic slurries, initial denitrification rates ranged from 0.1 to 0.7 nmoles N gas · soil−1 · min−1 for the mineral soils examined. The denitrification rate in aerobic aggregrates was approximately 1,000 times less, showing the strong inhibitory effect of O2 on the indigenous denitrifying enzymes.
Toposequences of Loess‐derived Soils in Southwestern Indiana
Authors: Norton L. D. , Franzmeier D. P. 
Published: July 2010

AbstractSoil properties are related to stratigraphy of parent materials and to hillslope position in southwestern Indiana where the landscape consists of gently rolling hillslopes and nearly level plains. Loess was uniform thickness downslope. Two distinct units were recognized. The upper (Peoria) loess contained about 15% less sand and had greater calcium carbonate equivalent, greater field water content, and lesser bulk density than the lower (sandy) loess. The Sangamon paleosol below the loess consisted of an upper slightly developed horizon and lower well developed horizons. The percentages of some heavy minerals were similar in the two loess units and similar in the two paleosol units, but differed between the loess and the paleosols. The lower loess showed slight soil formation. A fragipan was present only on summit and shoulder positions where the paleosol formed in weathered sandstone and shale, but not where it formed in outwash. Apparently there was slight soil formation in the lower loess before its surface was covered by the upper loess. Our data support the hypothesis that fragipans form in loess underlain by less permeable materials at certain depths and that silica (or silicate) acts as a bonding agent in fragipans. We believe that the fragipan forms by processes associated with the modern landscape, but its formation is influenced by pre‐Peoria soils or weathering zones.
Ammonia Volatilization Losses from Flooded Rice Soils
Authors: Mikkelsen D. S. , De Datta S. K. , Obcemea W. N. 
Published: July 2010

AbstractThe pH of the flood water in rice fields is largely determined by the chemical equilibria that exist between the CO2 balance achieved by the aquatic biota and the various solutes, solids, and gases in the water. Water pH values undergo diurnal changes, increasing by midday to values as high as pH 9.5–10 and decreasing as much as 2–3 pH units during the night. The pH of shallow flood water is greatly affected by the total respiration activity of all the heterotrophic organisms and the gross photosynthesis of the species present.Ammonium form fertilizers broadcast into a high pH water are highly susceptible to direct NH3 volatilization losses. Nitrogen losses from fertilizer broadcast into flood water on a fertile, neutral‐pH Maahas clay were as high as 20% of the amount applied, but losses varied depending upon water pH, the nitrogen source, and rate, time, and method of application. Losses from an acid Luisiana clay, where the flood water was not conducive to algal growth and did not exceed pH 6.8, produced NH3 volatilization losses consistently less than 1% of the total N applied. Placement of N fertilizer in the soil at depths of 10–12 cm reduced NH3 volatilization losses to less than 1% of the total N applied.
A Rapid Method for Estimating the Nitrogen‐Supplying Capability of a Soil
Authors: Fox R. H. , Piekielek W. P. 
Published: July 2010

AbstractNitrogen fertilizer recommendations in humid regions have been primarily based on crop N requirements without regard for the variability in the N‐supplying capability of the soil. We found (reported in a separate article) that two previously proposed N availability indexes, 0.01M NaHCO3 and boiling 0.01M CaCl2 extractable N, were well correlated (r = 0.77 and 0.86, respectively; P < 0.01 for both) with the capability of eight Pennsylvania soils to supply N to field grown corn, (Zea mays L.). However, the time and expense required for these analyses may preclude their routine use by soil testing laboratories. In seeking ways to shorten and simplify the analyses, we found that the ultraviolet (UV) absorption by the 0.01M NaHCO3 soil extract at 260 nm was as well correlated with the N‐supplying capability of the test soils (r = 0.865 P < 0.01) as the best of the previously evaluated extractable N indexes. This new method is as rapid, simple, and inexpensive as the methods currently used to measure availability of other essential nutrients in the soil. We also demonstrate how this method can be used to predict more accurately the fertilizer N needs for corn.
Absorption Rates of Ammonium and Nitrate by Red Kidney Beans under Salt and Water Stress
Authors: Frota J. N. E. , Tucker T. C. 
Published: July 2010

AbstractThe purpose of this study was to gain additional knowledge regarding the influence of salinity and water deficit on plant uptake of NH4+ and NO3‐. The absorption patterns of NH4+ and NO3‐ by red kidney beans (Phaseolus vulgaris L.) were determined under normal conditions (control), NaCl treatment (salt stress), and carbowax treatment (water stress) using an inverse isotope dilution technique with 15N. Salt and water stress inhibited the absorption of both NH4+ and NO3‐. There was no difference between these two stress treatments in NH4+ uptake, but carbowax restricted NO3‐ uptake more than did NaCl. Under NaCl salinity the plants absorbed the same amount of N independent of N source; under water stress more NH4+ than NO3‐ was absorbed. Water absorption was reduced by both stress treatments; N and water uptake were highly correlated. Root permeability decreased in plants subjected to stress. Dry matter production and total N per plant decreased, but the N percentage increased in the stressed plants.
Map Unit Composition Assessment Using Drainage Classes Defined by Landsat Data
Authors: Kirschner F. R. , Kaminsky S. A. , Weismiller R. A. , Sinclair H. R. , Hinzel E. J. 
Published: July 2010

AbstractSoil survey map units are designed such that the dominant soil represents the major proportion of the unit. At times, soil mapping delineations do not adequately represent conditions as stated in the map unit descriptions. Digital analysis of Landsat multispectral scanner (MSS) data provides a means of accurately delineating and quantifying soil map unit composition.Digital analysis of Landsat MSS data collected on 9 June 1973 was used to prepare a spectral map for a 430‐ha area in Clinton County, Indiana. Sixteen spectral classes were defined, representing 12 soil and 4 vegetation classes. The 12 spectral soil classes correlated with soil drainage characteristics and were grouped into four drainage classes. The four spectral vegetation classes were grouped for convenience into one vegetation class.The soil delineations produced using these groupings were compared to a conventionally prepared soil map. Three map units were investigated in detail: (i) Mahalasville silty clay loam, poorly drained; (ii) Reesville silt loam, 0 to 2% slopes, somewhat poorly drained; and (iii) Xenia silt loam, 2 to 6% slopes, eroded, moderately well drained.Results indicate that soil drainage characteristics can be identified. Correlation of drainage characteristics with soil series allows for the composition of soil map units to be accurately ascertained.
Efficient Amendment Use in Sodic Soil Reclamation
Authors: Prather R. J. , Goertzen J. O. , Rhoades J. D. , Frenkel H. 
Published: July 2010

AbstractA laboratory column study of sodic soil reclamation was carried out using two soils high in exchangeable sodium percentage (ESP) and cation exchange capacity (CEC). Three amendments (CaSO4·2H2O, CaCl2·2H2O, and H2SO4) were used singly and in combination to test their effectiveness and efficiencies with respect to amount of amendment, time, and leaching needed.As a single amendment, H2SO4 is more effective than CaSO4 and results in a more desirable ESP profile than CaCl2. Combining either CaCl2 or H2SO4 with CaSO4 (proportions of ¼ and ¾, respectively) appreciably reduced the time and leaching needed to achieve reclamation as compared with CaSO4 alone. Certain soil conditions preclude or make undesirable the use of CaSO4 alone. Combining amendments results in effective reclamation and a potential savings in amendment costs.