bluuebunny/crossref_metadata_2025_split huggingface dataset:
Soil‐pore Orientation and Faults
Authors: Low Alison J. , Douglas Lowell A. , Platt David W. 
Published: July 2010

AbstractThe orientation of soil pores was studied in order to assess the effect of faulting on soil pores. The results from soil samples collected adjacent to, in a fault zone, and at some distance from a fault were portrayed as rose diagrams and indicated the following: the shortest pores in all samples tend not to show any strongly developed orientation pattern; therefore, the long and midsized pores should be studied. Also, the orientation of these pores were similar in different samples of undisturbed soil from the same horizon, suggesting that the soil‐pore distribution can be characterized. Details of sample size for this characterization are also given. This work indicates that pore orientation can be used to further substantiate some megascopic observations and may be useful in documenting faulting histories, even where horizon displacement is lacking. However, in such cases, pore data will not yield unqualified conclusions.Pore orientation patterns may change very little with time.
Surface Soil Physical Properties after 36 Years of Cropping to Winter Wheat
Authors: Unger Paul W. 
Published: July 2010

AbstractA dryland tillage and cropping system study for winter wheat (Triticum aestivum L.) was conducted on Pullman clay loam (fine, mixed, thermic Torrertic Paleustoll) from 1941 to 1977, a period much longer than most field studies. In 1977, soil samples were collected from the surface layer to evaluate effects of the long‐term tillage and cropping practices on dry and water‐stable aggregate distribution, organic matter (OM) concentration, modulus of rupture, penetrometer resistance, and bulk density of clods. Oneway disk tillage resulted in significantly fewer small dry aggregates than sweep tillage in the wheat‐fallow system, but had no significant effect in the continuous wheat system. Mean weight diameters (MWD) were similar for all tillage methods. Oneway tillage resulted in more < 0.25‐mm diameter water‐stable aggregates than sweep tillage in both cropping systems, resulting in lower MWD for oneway than for sweep tillage. Organic matter concentration was lower for oneway than for sweep tillage in both systems, while continuous wheat resulted in higher OM concentration than wheat‐fallow for comparable tillage methods. Slight changes from 1966 to 1977 indicated that soil OM concentration was at or nearly in equilibrium with prevailing management and climatic conditions. Modulus of rupture of briquettes and resistance of briquette fragments to fracture with a penetrometer were inversely related to OM concentration, but no tillage method or cropping system had an overriding influence on soil physical properties. Dry aggregate analyses indicated that the soil did not contain enough coarse aggregates to control wind erosion, indicating the need to maintain residues on the soil surface to aid wind erosion control.
Organic and Inorganic Sulfur Constituents of a Forest Soil and Their Relationship to Microbial Activity
Authors: David M. B. , Mitchell M. J. , Nakas J. P. 
Published: July 2010

AbstractSulfur (S) constituents, microbial biomass, and sulfohydrolase activity were determined for each soil horizon at both hardwood and conifer sites in a Becket soil (Adirondack Mountains, New York). Drying of soil before analysis altered the S constituents. There was a threefold increase (p < 0.05) in sulfate in the organic horizons. Total S was greatest in the O horizons with 2,010 and 1,690 µg S/g in conifer and hardwood solums, respectively. Mineral soil had a maximum S concentration in the B21h horizon. Sulfate concentrations were a small proportion (<15%) of total S in B horizons. Organic S was dominant (93% of total S) in all horizons. Carbon‐bonded S and ester sulfate were 74 and 18% of total S, respectively. Microbial biomass was greatest in the 01 horizon of both hardwood and conifer solums (59 and 70 mg biomass C · 100 g−1 dry mass, respectively). The B21h horizon contained the greatest biomass in the mineral soil. Sulfohydrolase activity exhibited the same distribution. Total S, carbon‐bonded S, and ester sulfate were all positively correlated (p < 0.05) to percent organic matter in the soil horizons. Correlations between microbial biomass and sulfohydrolase activity with organic S indicate the potential for microbial S transformations. Sulfate formation by mineralization may be more important than exogenous inputs. This has major implications for assessing the impact of atmospheric S deposition on soils.
Time, Rate, and Method of Phosphorus Application for Continuously Double‐cropped Wheat and Soybeans
Authors: Touchton J. T. , Hargrove W. L. , Sharpe R. R. , Boswell F. C. 
Published: July 2010

AbstractCurrently, phosphorus (P) fertilizer recommendations for double‐cropped wheat (Triticum aestivum L.) and soybeans (Glycine max L. Merr.) are based on data from monocropping conventional tillage systems. The purpose of this 3‐year study on an eroded Ultisol was to compare times (fall, spring, and fall plus spring) and rates (0, 32, 64, and 128 kg ha−1 year−1) of P applications for double‐cropped wheat and soybeans grown with disk tillage and no‐tillage production practices. Disk tillage was used to incorporate P; otherwise, tillage implements were not used. Although most of the applied P was concentrated in the surface 7.5 cm of soil, it did not affect extractable soil levels of K, Ca, Mg, Cu, Zn, and Mn. Applied P did, however, reduce Cu and Zn concentrations in both soybean and wheat tissue, but the reduction probably was not great enough to affect yields. Yield response to applied P was obtained, but this response was primarily with the lowest P rate; average yields for 0 and 32 kg ha−1 year−1 were 2,330 and 2,750 kg/ha, respectively, for wheat and 2,210 and 2,690 kg/ha, respectively, for soybeans.Time of application did not affect yields or nutrient concentrations of either crop. Nutrient concentrations in soybean leaves did not differ among tillage systems, but soybean yields averaged 200 kg/ha higher with no‐tillage than disk tillage. With wheat, nutrient concentrations were lower and forage and grain yields were higher with disk‐ than no‐tillage. Yield differences between tillage systems were essentially the same for no P as for any rate of applied P, which suggests that these differences between tillage systems were due to tillage rather than method of application. The data suggest that current P recommendations for monocropping systems are suitable for double‐cropping systems but P recommendations for disk‐ and no‐tillage systems should be based on soil samples taken from the upper 7.5 cm of soil rather than the more common 0‐ to 20‐cm depth.
Comparison of Batch and Miscible Displacement Techniques to Describe Potassium Adsorption Kinetics in Delaware Soils
Authors: Sparks D. L. , Rechcigl J. E. 
Published: July 2010

AbstractKinetics of potassium (K) adsorption in three soils were compared using batch equilibrium and miscible displacement techniques. The batch method reached equilibrium sooner than miscible displacement in all cases. Greater clay content did not affect the equilibrium time using the batch technique but increased that time for miscible displacement.The percent‐K adsorption was closely related to (time)1/2 indicating diffusion‐controlled exchange. Relative rate coefficients were significantly higher for batch than for miscible displacement.Miscible displacement simulates solute movement in soils under field conditions, and since flow rate and leachate volume can easily be adjusted, miscible displacement has great advantages for rapid reactions. Batch techniques require separation of solid and solution by centrifugation and/or filtration in which the time of separation of solid from liquid phases is not precisely known.
An Improved Thermocouple Hygrometer for In‐situ Measurements of Soil Water Potential
Authors: Brunini O. , Thurtell G. W. 
Published: July 2010

AbstractA new dewpoint hygrometer for in‐situ measurements of soil water potential was designed and its performance evaluated. A porous silver membrane serves as the hydraulic connection between the soil and the measuring cavity which encloses a four‐terminal thermojunction made by cross welding chromel and constantan wires 0.001 in. (0.00254 cm) in diameter. The membranes were screwed to the copper body of the hygrometer and such configuration minimized the temperature difference between the vapor source and the reference junctions. When a thermal gradient was imposed on a hygrometer placed horizontally in a soil column, the maximum voltage offset observed was 0.05µV, but the soil water potential values as indicated by the hygrometer readings remained constant at −0.56MPa.This new device has a fast response for water flow with a time constant of approximately 5 min, and the time constant for salt diffusion in and out of the membranes is about 8 min. The results of soil water potential measurements under corn (Zea mays) plant hybrid United 108 grown in a growth chamber environment have shown that this new device is capable of following the changes in soil water potential very well. The difference in water potential observed between leaf and soil after the plant had been left several hours in the dark appeared to be related to uneven moisture distribution in the pot, and the plant was responding to the average soil water potential.
Crystallization of Iron(III) Phosphate at Room Temperature
Authors: Hsu Pa Ho 
Published: July 2010

AbstractFerric nitrate, sodium dihydrogen phosphate, and sodium hydroxide solutions were mixed in a variety of combinations and aged at room temperature. The results showed that, with solutions 0.001M in Fe, 0.0002 to 0.001M in phosphate, and NaOH/Fe molar ratios ranging from 0 to 3 (pH 2.6 to 7.8), all precipitates were amorphous basic iron(III) phosphates without any tendency to crystallize toward strengite‐type compounds for up to at least 66 months.With 0.01M in Fe, metastrengite was observed from samples 0.03 to 0.06M in phosphate (pH 2.0 to 2.4) 24 months after preparation, but the reaction product was positively charged amorphous basic iron phosphate if the sample was dispersed in 0.01M in phosphate (pH 1.8) during the entire period of study. These positively charged particles were rapidly precipitable with sulfate. The sample 0.02M in phosphate was on the borderline for metastrengite formation.
Diurnal Variability in Rate of Emission of Nitrous Oxide from Soils
Authors: Blackmer A. M. , Robbins S. G. , Bremner J. M. 
Published: July 2010

AbstractDiurnal variability in the rate of emission of nitrous oxide (N2O) from Iowa soils was studied by using a chamber technique to measure the N2O emission rates at sites on fertilized and unfertilized soils at 1‐ or 2‐h intervals for periods of from 1 to 5 d. The coefficients of variation for the rates of N2O emission observed at these sites within 24‐h periods ranged from 12 to 66% and averaged 38%. As much as 90% of the diurnal variability observed could be attributed to diurnal N2O emission patterns related to changes in soil temperature. Observations reported suggest that these patterns were caused largely by changes in the solubility of N2O in soil water induced by diurnal changes in soil temperature, that the amplitudes of these patterns were determined largely by the amounts of water and N2O in the surface soil, that the times of minima and maxima in these patterns were determined by the depth at which temperature‐induced changes in the solubility of N2O in water were significant, and that neither the amplitudes nor the times of minima and maxima in these patterns can be predicted solely from soil temperature. Data reported show that there is no short time during a 24‐h period that is always satisfactory for assessing the amount of N2O evolved during that period.
L‐Histidine Ammonia‐Lyase Activity in Soils
Authors: Frankenberger W. T. , Johanson J. B. 
Published: July 2010

AbstractApproximately 20 to 40% of the total nitrogen (N) in most surface soils is in the form of amino acids. Because of the importance of amino acids as a N source for plant and microbial growth, this work was carried out to study the enzyme that catalyzes the deamination of L‐histidine in soils. A simple, precise, and sensitive method to assay L‐histidine ammonia‐lyase (EC 4.3.1.3) activity in soils is described. This enzyme catalyzes the deamination of L‐histidine and produces urocanate and ammonia. The method involves determination by steam distillation of the ammonium (NH4+) produced by L‐histidine NH3‐lyase activity when soil is incubated with buffered (0.1M Tris, pH 9.0) L‐histidine solution and toluene at 37°C for 48 h. Results show that the rate of NH4‐N released through soil L‐histidine NH3‐lyase activity exhibited a buffer pH optimum of 9.0. The reaction rate of this enzyme approached zero‐order kinetics when 50 mM of L‐histidine solution was added to soils. The D‐isomer of histidine was also deaminated in soils but was only 40% of the activity of the L‐isomer at saturating conditions of the substrate. The dependence of the reaction rate on the amount of enzyme present was linear up to 5 g of soil. Under the standard conditions, the accumulation of NH4‐N was linear with time for at least 168 h. However, in the absence of toluene the NH4‐N released with time followed an exponential relationship which might be due to induction of the enzyme by its substrate and a multienzyme system that degrades urocanate and its reaction products. The optimal temperature for soil L‐histidine NH3‐lyase activity occurred at 80°C and denaturation began at 85°C. Among the various pretreatments that affected L‐histidine NH3‐lyase activity in soils, 2‐mercaptoethanol, cysteine, CaCl2, and MgSO4 activated this enzyme by an average of 12, 16, 11, and 11%, respectively. Treatments with formaldehyde, phenyl mercuric acetate, NaF, and NaAsO2 inhibited the activity considerably.
Composition of a Conover‐Brookston Map Unit in Southeastern Michigan
Authors: Asady G. H. , Whiteside E. P. 
Published: July 2010

AbstractA Conover‐Brookston soil mapping unit, named on the basis of point‐transect observations after its delineation, was reevaluated through laboratory characterization of the major components of this map unit. Eight Conover (fine‐loamy, mixed, mesic Udollic Ochraqualf) and eight Brookston (fine‐loamy, mixed, mesic Typic Argiaquoll) pedons, identified by the transect observations, were investigated by laboratory determinations.The particle‐size distributions indicated some translocation of clay from the surface to the subsoil in each series. However, even in those pedons with other characteristics of an argillic horizon, the ratios of fine‐clay in total clay of B2/Ap horizons were insufficient for an argillic horizon as defined in Soil Taxonomy. Alternative criteria are proposed.The 16 pedons covered the whole particle‐size range of the fineloamy family. The transects of the map unit after its delineation overestimated its homogeneity, judged by the laboratory analyses.
The Genesis of Certain Soil Profiles on an Archaeological Site in Southern Greece
Authors: Haidouti C. , Yassoglou N. J. 
Published: July 2010

AbstractGenetic studies were conducted on soil profiles developed on an archaeological site in southwestern Greece. The parent materials of the profiles were unconsolidated Holocene and Pliocene deposits. Argillic horizons formed through the movement of montmorillonite developed in 2,000 to 3,000 years. Cambic horizons formed by the removal of carbonates developed in < 900 years. The depth of pedogenesis was influenced by the consolidation of the parent material and presence of limestone boulders.Changes in the mineralogical composition during soil development were the leaching of carbonates, translocation of montmorillonite from the surface horizon to the Bt horizon, and changes in the proportion of iron oxides extracted by ammonium oxalate.
Time and Frequency of Irrigation Effects on Sunflower Production and Water Use
Authors: Unger Paul W. 
Published: July 2010

AbstractSunflower (Helianthus annuus L.) production has greatly increased in the U. S. in recent years, with some being produced under irrigation in the Southern Great Plains. However, because of limited water supplies in the Southern Great Plains, sunflower usually is not fully irrigated. The objective of this study was to determine the influence of limited irrigation on sunflower growth, seed yield and quality, oil percent and quality, and water use and use efficiency. Treatments providing one or two irrigations at readily identifiable growth stages were compared with treatments providing no, adequate, and full irrigation. Sunflower irrigated before flowering averaged 17 cm taller than those not irrigated between emergence and flowering. Seed yields averaged highest (2.49 t/ha) with full irrigation, but in individual years, differences between full irrigation and other treatments were not always significant. Usually, the highest seed yield resulted from flowering or late flowering irrigations. These irrigations usually also resulted in the highest seed test weight and weight/seed. Oil percent averaged highest (48.8%) for the emergence plus late flowering irrigation treatment and lowest (43.4%) with the emergence plus budding treatment. Irrigation treatments significantly affected linoleic and oleic acid concentrations of the oil, but the maximum difference among treatments was only four and five percentage units for linoleic and oleic acids, respectively.Total water use increased with increased number of irrigations, but yield increases were not proportional to water use, especially for the adequate and full irrigation treatments. With these treatments, water‐use efficiency was less than for limited irrigation treatments that provided adequate water from flowering to late flowering.
Effect of Dry‐Season Soil Management of Water Conservation for the Succeeding Rice Crop in a Tropical Soil
Authors: Hundal S. S. , De Datta S. K. 
Published: July 2010

AbstractIn tropical Asia, soil water conservation during the dry‐season fallow is critical for early establishment of the first rice (Oryza sativa L.) crop and increases in sequential cropping intensity under rainfed conditions. Five dry‐season fallow soil water conservation techniques using shallow rotovation (soil mulch), deep plowing followed by rotovation, herbicide‐treated bare and straw mulched soil, and weedy control were evaluated on a clay soil. Soil water changes were monitored weekly to the 1.05‐m soil depth. Soil temperature at the 10‐cm depth, soil matric potential at the 15‐cm depth, and fluctuations in groundwater table were measured regularly.Highest soil temperatures were obtained in the bare soil treatment. The straw mulch application maintained the lowest temperatures. By the end of the dry season, the soil had dried to the 1‐m depth in the weedy control compared to 15 cm in soil mulch, 30 cm in straw mulch, and 45 cm in the bare soil treatment. Starting with initial soil water contents close to field capacity, a maximum water depletion of 248, 86, 55, 35, and 58 mm occurred in the weedy control, bare soil, straw mulch, plowed and rotovated, and rotovated treatments, respectively, at the end of the dry season. Groundwater table during this period varied from about the 1.5‐ to 1.75‐m soil depth. Rainfall requirement was significantly reduced and early crop establishment was made possible when soil was kept weed‐free during the dry‐season fallow. Minor differences in water conservation occurred among soil mulch, straw mulch, and bare soil systems.
Separating Soil Iron‐ and Manganese‐Oxide Fractions for Microelement Analysis
Authors: Shuman L. M. 
Published: July 2010

AbstractSince sodium dithionite (Na2S2O4) is often contaminated with zinc (Zn) and can form metal sulfide precipitates, it is not suitable for solubilizing iron (Fe) oxides in fractionation schemes for soil microelements. The objective was to find an alternate method to solubilize crystalline Fe oxides that would fit into a scheme including extractants for amorphous Fe and manganese (Mn) oxides. Three soils were extracted with seven reagents designed to remove amorphous and/or crystalline Fe or Mn oxides [0.1M Na4P2O7, pH 10.0; 0.2M (NH4)2C2O4 in 0.2M H2C2O4, pH 3.0 (oxalate); 0.1M NH2OH‐HCl, pH 2.0; 1.0M NH2OH‐HCl in 25% acetic acid; 0.1M ascorbic acid in the oxalate solution; 0.1 g SnCl2 per gram of soil in the oxalate solution; and 1.0 g dithionite per gram of soil in citrate buffer]. The Na4P2O7, an extractant for elements associated with the organic fraction, extracted amounts of Fe similar to that for the oxalate solution. The two NH2OH‐HCl extractants solubilized very little Fe (<1% total), but NH2OH‐HCl alone solubilized as much Mn as most of the other extractants indicating that it is specific for Mn oxides. The ascorbic acid‐oxalate and SnCl2‐oxalate experimental methods extracted amounts of Fe similar to the dithionite method and amounts of Al higher than the dithionite method. Of the amorphous Fe‐oxide extractants, the oxalate solution solubilized the most Zn and Cu, whereas of the crystalline Fe‐oxide extractants, the ascorbic acid‐oxalate solubilized the highest amounts of Zn and Cu. The extractants suggested for a fractionation scheme are NH2OH‐HCl for Mn oxides, oxalate solution shaken with the soil in the dark for amorphous Fe oxides, and ascorbic acid‐oxalate for crystalline Fe oxides.
Influence of Soil Moisture on Smectite Formation in Soils Derived from Serpentinite
Authors: Istok J. D. , Harward M. E. 
Published: July 2010

AbstractX‐ray diffraction (XRD), differential thermal analysis (DTA), and transmission electron microscopy (TEM) were used to characterize the phyllosilicates in a catena of soils derived from serpentinite in southwestern Oregon. Serpentine (variety chrysotile) and chlorite were the phyllosilicates in the bedrock and in the <2‐µm fraction of soil samples from the two well‐drained profiles. Samples from the two soils which were deeper, finer‐textured, and more poorly drained consisted of smectite, serpentine, and chlorite. The data indicate that smectite is forming from serpentine and/or chlorite in poorly drained landscape positions. The abundance of amorphous material, revealed by TEM, may suggest a mechanism for smectite formation in these soils.
Measurement of Hydraulic Conductivity of Unsaturated Soils with Thermocouple Psychrometers
Authors: Daniel David E. 
Published: July 2010

AbstractA method of measuring the hydraulic conductivity of unsaturated soil using the instantaneous profile method with psychrometric probes to measure water potential is developed and described. Soil is compacted into cylindrical tubes, and the tubes are sealed and instrumented with thermocouple psychrometers. The soil is moistened or dried from one end of the tube. Psychrometers are read periodically. Hydraulic conductivity is computed from the psychrometer readings and the appropriate moisture characteristic curve for the soil and then plotted as a function of water potential, water content, or degree of saturation.Hydraulic conductivities of six soils were measured at water potentials as low as −80 bar. The measured hydraulic conductivities and moisture characteristic curves were used along with the known boundary flux in a computer program to calculate the final water content profiles. Computed and measured final water content profiles agreed tolerably well.