bluuebunny/crossref_metadata_2025_split huggingface dataset:
Compaction and Soil Structure Modification by Wheel Traffic in the Northern Corn Belt
Authors: Voorhees W. B. , Senst C. G. , Nelson W. W. 
Published: July 2010

AbstractIncreasing size and weight of farm tractors is causing increasing concern about soil compaction. Controlled wheel‐traffic studies in Minnesota on a silty clay loam showed that wheel traffic of normal farming operations could compact the soil to a 45‐cm depth. Penetrometer resistance was a more sensitive indicator of soil compaction than was bulk density. Wheel traffic increased soil bulk density by 20% or less, whereas penetrometer resistance was increased by as much as 400%. Fall tillage essentially alleviated bulk compaction in the 0‐ to 15‐cm layer. Plowing was more effective than disking or chiseling in decreasing compaction in the 15‐ to 30‐cm layer. Compared with plowing, bulk density and penetrometer resistance values for chiseling or disking were about 5 and 40% higher, respectively. Compaction below the tillage depth was not completely ameliorated by annual freezing and thawing.Wheel‐induced compaction was more persistent in individual soil structure units than in bulk soil. Strength and density of wheel tracked clods were greater and average aggregate diamter was larger than that of nontracked clods, a difference which persisted overwinter.
Ammonia Volatilization Reaction Mechanism Between Ammonium Sulfate and Carbonate Systems
Authors: Feagley S. E. , Hossner L. R. 
Published: July 2010

AbstractThe mechanism by which NH3 is lost in the reaction between (NH4)2 SO4 and CaCO3, BaCO3, MgCO3, and a calcareous Norwood silt loam soil was investigated. Results obtained in the laboratory indicated that the reaction proceeded through an NH4HCO3 intermediate.The ratio of NH3 to CO2 volatilized approached a 2:1 ratio of NH3/CO2 gases for the first 2 to 6 hours of the reaction. It then decreased to an apparent equilibrium ratio of 1:1 for the remainder of the 96‐hour reaction period. The pH of the reaction interface between (NH4)2SO4 surface applied to CaCO3 was never > 8.4. These data indicate that at no point was there a high enough pH to form (NH4)2CO3. Thus, if any solid formed it would be NH4HCO3 and not (NH4)2CO3.
Urea Fertilizer Effects on Dissolved Nutrient Concentrations in Some Forest Soils
Authors: Otchere‐Boateng J. , Ballard T. M. 
Published: July 2010

AbstractNutrient concentrations in soil solutions near the surface and below the root zone were measured for 8 months after fall application of urea (448 kg N/ha) to four soils under second‐growth forest in southwestern British Columbia. Surface soil solution pH increased due to ureolysis within a few days, while concentrations of some cations were reduced, with Ca and Mg decreasing more than K and Na. Nitrate concentrations peaked at least 3 months after fertilization. With pH decline accompanying nitrification in fertilized plots, concentrations of Ca and Mg increased substantially over concentrations in unfertilized control plots whereas K and Na showed smaller increases. Effects on Ca, Mg, K, and Na are consistent with interpretations based on pH‐dependent cation exchange capacity and Donnan equilibria. Maximum total N, NO3‐N, and Ca concentrations below the root zone were 11.2, 11.0, and 10.0 mg/liter, respectively, and occurred with a recently afforested, coarse‐textured soil which was low in incorporated organic matter and lacked a forest floor.
Gravimetric vs. Volumetric Determination of Water Storage in Vertically Unstable Tillage Layers
Authors: Steinhardt Reuven 
Published: July 2010

AbstractMethods of determining water storage (W) in a tillage layer of changing height are analyzed to compare the effects of agrotechnical management on W. Changes in W may be evaluated from a single estimate of the solid mass per unit area at a state of reference and periodic observations of the gravimetric water content of the tillage layer, which is equivalent to the usual procedure in stable soils.
Laterally Confined Flow From a Point Source at the Surface of an Inhomogeneous Soil Column
Authors: Merrill S. D. , Raats P. A. C. , Dirksen C. 
Published: July 2010

AbstractSolution of a linearized flow equation for steady, axisymmetric, laterally confined infiltration from a point source located at the soil surface is compared with pressure head patterns measured in an undisturbed column of sandy loam. The geometry approximates an array of trickle irrigation emitters. The hydraulic conductivity could be represented as an exponential function of both the pressure head and the depth in the column. This implies that steady, multidimensional flow in the column is described by a linear flow equation.Measured and predicted distributions of pressure head agreed most closely at an application rate of 0.5 cm/day. Increase in the size of a saturated zone about the point source at application rates higher than 0.5 cm/day caused isolines of pressure head to be distorted from the predicted shape. Flow patterns for homogeneous and heterogeneous soil are compared.Trickle irrigation systems are usually operated intermittently. Measured distributions of pressure heads under intermittent application were compared with steady infiltration patterns. A steady‐flow solution will give an approximate prediction of intermittent pressure head patterns for continuously repeated application cycles over part of the flow region and during part of the time.
Serious Interferences in the Determination of Trace Metals in Soils by Flame and Flameless Atomic Absorption Spectrometry
Authors: Mubarak A. , Hageman L. , Howald R. A. , Woodriff R. 
Published: July 2010

AbstractNegative interfering effects on the carbon rod atomizer (CRA) absorbances of Mn, Fe, and Ni were found to occur in the presence of the chlorides of the major cations (Ca, Mg, Na) in the soil solution. These interferences were corrected either by precipitation of the chlorides with silver nitrate or by incorporating a relatively high level of sulfuric or nitric acid into the sample volume. Magnesium ion, irrespective of the associated anion, was found to lower the Cd signal on the CRA. High concentrations of MgSO4 caused lowering of the Mn signal when using air‐acetylene flame. This lowering effect of MgSO4 was avoided upon using N2O‐acetylene flame. No interferences were noticed for Mn and Zn when using the constant temperature furnace developed at Montana State Univ.
Formation of Humic Acid Like Compounds by the Ectomycorrhizal Fungus, Pisolithus tinctorius
Authors: Tan K. H. , Sihanonth P. , Todd R. L. 
Published: July 2010

AbstractFormation of organic compounds by the ectomycorrhizal fungus, Pisolithus tinctorius, was studied to establish the relationship of these microbial products to humic and fulvic acids. The fungus was grown in a Melins‐Norkrans liquid culture with either sucrose or a mixture of L‐malic and L‐succinic acid as the C and energy source. The biologically synthesized substances were characterized by chemical and infrared analyses. The fungus grown on the malic‐succinic acid medium produced a black substance, whereas the organism grown on sucrose yielded only small amounts of a greenish‐brown colored compound. The greenish‐brown substance behaved similarly to fulvic and humic acids, when subjected to fractionation procedures using NaOH and HCl. The fraction soluble in base and acid had an infrared spectrum resembling that of fulvic acids. The fraction soluble in NaOH but insoluble in HCl had infrared features of humic acid. The black substance was insoluble in NaOH and HCl, and identification of infrared spectra revealed the black colored product to be uronic acids.
Influence of Polyethylene Mulch and Magnesium Salts on Tomatoes Growing on Loamy Sand
Authors: Jones U. S. , Jones T. L. 
Published: July 2010

AbstractPlant‐soil responses to mulching with 0.0375 mm thick white‐overblack polyethylene plastic and to two sources of Mg were studied by analyzing soil samples, plant tissues, and yields associated with three crops of irrigated tomatoes (Lycopersicon esculentum Mill.). These crops were grown on 5.51 m2 plots of Blanton loamy sand in 1976‐77. Ten and 20 kg/ha of Mg as MgSO4 · 7H2O and 20 kg/ha of Mg as CaMg(CO3)2 were added each season to mulched and unmulched soil. Yield of marketable tomatoes, S and Mg content of the fourth leaf from tip, and exchangeable Ca, Mg, and buffer pH of soil to a depth of 60‐cm were measured. Yield was significantly increased in the first crop where Mg was added, either as MgSO4 · 7H2O or dolomite on mulched soil. Tomato‐leaf Mg (0.78%) of the second crop was greatest where 20 kg/ha of Mg as MgSO4 · 7H2O was added to the mulched plots although the yield increase was not significant. Leaf Mg content was significantly increased by 20 kg/ha of Mg as MgSO4 · 7H2O in second and third crops whether or not plastic mulch was used. Dolomite increased Mg in the leaf of the third crop. Mulched soil (0 to 15 cm deep) had a higher buffer pH and exchangeable Mg and Ca than did the uncovered soil. No significant difference in cations was noted at greater soil depths.
Partial Substitution of Mycorrhizal Fungi for Phosphorus Fertilization in the Greenhouse Culture of Citrus
Authors: Menge J. A. , Labanauskas C. K. , Johnson E. L. V. , Platt R. G. 
Published: July 2010

AbstractThe interaction between P fertilization of citrus and the mycorrhizal fungus Glomus fasciculatus was examined in a greenhouse study. A low fertility loamy sand (4.6 ppm P) was provided with all necessary soil nutrients except P. This soil received superphosphate [Ca(H2PO4)2 · H2O] at rates of 0, 6, 28, 56, 278, and 556 ppm of P. Seven replicate mycorrhizal and nonmycorrhizal Brazilian sour orange and Troyer citrange seedlings were grown at each P fertility level. After 5 months, mycorrhizal sour orange which received 0 fertilizer P were similar in size to non‐mycorrhizal sour orange which were fertilized with 278 ppm P. Mycorrhizal citrange which received 0 fertilizer P were similar in size to nonmycorrhizal citrange which were fertilized with 56 ppm P. Dry weights of mycorrhizal sour orange seedlings were significantly greater than nonmycorrhizal sour orange seedlings when fertilized with 0, 6, 28, and 56 ppm P (947, 1089, 347, and 253% greater, respectively). Dry weights of mycorrhizal citrange seedlings were significantly greater than nonmycorrhizal citrange seedlings only when fertilized with 0 and 6 ppm P (746 and 300% greater, respectively). The %P in leaves of both citrus cultivars was enhanced by the mycorrhizal association at all P fertility levels. Variation in absorption of K, Mg, and Na by the citrus cultivars appeared to be primarily influenced by P concentrations of the seedlings. Variation in absorption of Zn, Cu, and Mn appeared to be influenced by both P concentrations of the seedlings and the presence of the mycorrhizal fungus. The number of G. fasciculatus spores/cm3 of soil which were associated with inoculated plants decreased with increasing P fertility levels. With mycorrhizal sour orange, numbers of spores decreased from 10.1 spores/cm3 soil at 56 ppm P soil to 0 spores/cm3 soil with plants at 556 ppm P. With mycorrhizal citrange, numbers of spores decreased from 5.7 spores/cm3 soil at 28 ppm P to 0 spores/cm3 soil at 56 ppm P. No correlation was found between soil P or % P in leaves, roots or stems of seedlings and the elimination of spore production.
Mössbauer and X‐Ray Evidence for the Pedogenic Transformation of Hematite to Goethite
Authors: Bigham J. M. , Golden D. C. , Bowen L. H. , Buol S. W. , Weed S. B. 
Published: July 2010

AbstractSoils of the Appling series (Typic Hapludults; clayey, kaolinitic, thermic) are extensive in the Piedmont Province of the southeastern United States. Typically, these soils exhibit colors grading from brown (7.5YR) in the upper B horizons to red (2.5YR) in the saprolite. Fine clay separates (<0.2µm) from the brown (B21t horizon) and red (C2 borizon) zones of a representative pedon of the Appling soil were analyzed to determine if the color transition reflected a change in iron mineralogy. Concentration of secondary iron forms by alkali dissolution of gibbsite and silicate clay minerals enabled the x‐ray identification of aluminous geothite and hematite in the C2 clay but only aluminous goethite in the B21t material. These results were substantiated by Mössbauer spectroscopic analyses of the natural clays, which gave spectra characteristic of finely divided hematite and/or goethite. Subnormal effective internal magnetic fields (relative to standard goethite and hematite) were also measured and were in keeping with the effect of Al substitution. Presence of both goethite and hematite in the saprolite but only goethite in the B21t material suggests a pedogenic transformation of hematite to goethite.
In Situ Transformations of Nitrogen‐15 Labeled Materials in Sonoran Desert Soils
Authors: Westerman R. L. , Tucker T. C. 
Published: July 2010

AbstractInfluences of ammonium, nitrate, organic N sources and organic C amendments on microbial respiration, N transformations and gaseous losses were measured under natural environmental conditions in two field experiments. Microbial respiration was increased by addition of wheat straw and barley grain. Addition of N as (15NH4)2SO4 and K15NO3 alone did not increase CO2 evolution significantly.Significant immobilization of added inorganic‐15N occurred with few exceptions in all treatments except nitrate alone. Organic‐15N in soils amended with wheat straw increased with increasing N rates with both inorganic N sources. Inorganic‐15N was practically void in both soils at the end of 12 months. Mineralization of 15N‐labeled barley grain occurred but at a very low rate and no significant accumulations of inorganic‐15N were observed.Gaseous losses of N at the end of 12 months varied from 73 to 94% of the inorganic‐N added alone, with the greatest loss occurring from K15NO3. The incorporation of wheat straw stimulated immobilization of added N and reduced gaseous losses to 30 to 86% of the total N applied and the smallest loss occurred with (15NH4)2SO4. The average loss of mineralized organic‐15N derived from barley grain for the two soils was 19% of the total N added. Most of the gaseous losses occurred within the first 3 months, the period of the measurable rainfall.Analyses of subdivided soil sections (0–5 and 5–10 cm) showed that 95 to 100% of 15N remaining in the soil was in the upper 5‐cm layer indicating that leaching was not appreciable in any treatment.
Interaction of Added Gypsum in Alkaline Soils with Uptake of Iron, Molybdenum, Manganese, and Zinc by Sorghum
Authors: Olsen S. R. , Watanabe F. S. 
Published: July 2010

AbstractExperiments with tomato plants (Lycopersicon esculentum Mill.) in nutrient cultures indicated previously that Mo accentuated Fe deficiency at low levels of available Fe. This interaction may be important in alkaline soils where pH favors a low Fe availability and high Mo availability from native soil levels. When such interactions exist, this information will help interpret the relationship between response predicted by a soil test for available Fe and actual response. This interaction was confirmed in six soils where sorghum plants (Sorghum bicolor L. Moench. var. RS‐610) increased in Fe uptake and/or Fe concentration as Mo was decreased by adding CaSO4 at 30 ppm of S. The CaSO4 decreased Mo from 2.33 to 1.26 ppm and increased Fe from 56 to 65 ppm in sorghum. An increase in Mo above native levels decreased the Fe concentration from 57 to 51 ppm and Fe uptake frmo 369 to 306 µg/pot in sorghum. Also, CaSO4 consistently increased Mn concentrations from 70 to 90 ppm, and Zn from 56 to 80 ppm in sorghum. Knowledge of these interactions will help to interpret plant responses to natural levels of these micronutrient in soils and disturbed lands or to induced levels from sewage, other wastes, and fertilizers.
Nitrogen Release Patterns from Deep Placement Sites of Urea in a Wetland Rice Soil
Authors: Savant N. K. , De Datta S. K. 
Published: July 2010

AbstractRelease patterns of N from deep placement sites of prilled urea (PU), supergranule urea (SGU), sulfur‐coated urea (SCU), and urea in mudball (MBU) were studied in in situ wetland Maahas clay at the International Rice Research Institute. Nitrogen release from PU and SGU was rapid during first day after placement and decreased thereafter. Nitrogen release from urea in a mudball was slower than that from PU or SGU. Deep placed SCU released N at a markedly slower rate than MBU throughout 45 days after placement. Nitrogen release from deep placement sites of the different forms of urea appeared to be a diffusion‐controlled process.
Soil Properties Influencing Strength of Canfield and Geeburg Soils
Authors: McCormack D. E. , Wilding L. P. 
Published: July 2010

AbstractThis study was conducted to determine the relationships between in situ shear strength and soil properties in two contrasting soil series. Shear strength was measured using a vane forced into the soil by a truck‐mounted hydraulic sampler. Selected horizons at five sites of each soil series were tested. Vane shear tests were performed both in the fall and in the spring; 144 tests were performed.Soil moisture content, bulk density, and clay content were found to be of most influence on vane shear strength. Multiple regression analysis showed that coarse clay content is positively correlated with shear strength and fine clay content is negatively correlated. These four variables explain 83% of the variation in vane shear strength. Remolded shear strength in the Bt horizons of both soils is < 0.15 kg/cm2. The soil properties that explain most of the variation in shear strength are used in the classification of soil series, or are directly associated with these properties. Determination of soil strength using the vane shear test is quick and inexpensive. The high correlation between the test results and soil properties suggests that further study of the potential use of the vane shear test in the soil survey is warranted.
Inhibition of Nitrification by Acetylene
Authors: Walter H. M. , Keeney D. R. , Fillery I. R. 
Published: July 2010

AbstractThe effect of C2H2 on nitrification in soils was determined to evaluate the use of C2H2 in field and laboratory denitrification studies. The presence of as little as 0.1% (vol/vol) C2H2 completely inhibited nitrification. The effect of C2H2 was reversible, but an 8‐ to 10‐day period was required before nitrification returned to the rate in the control. The results suggest that the C2H2 approach must be limited to those experiments in which either only nitrate fertilizers are used or where nitrification is assumed complete before denitrification commences.
Dissolution and Transport of Gypsum in Soils: II. Experimental
Authors: Glas T. K. , Klute A. , McWhorter D. B. 
Published: July 2010

AbstractExperimental information on the dissolution of gypsum and the subsequent transport of the dissolved species in a soil‐water system was obtained by adding distilled water to the top of 30‐cm long columns containing a soil‐gypsum mixture and by measuring the calcium concentration in the solution phase as a function of time at different positions in the columns. The measured concentration‐time curves are compared with results from two models — the first based on equilibrium chemical principles and the mixing‐cell concept, and the second based on a combination of the one‐dimensional convection‐dispersion equation and a first‐order kinetic expression describing the dissolution process. Under the specific experimental conditions studied, the dissolution process appeared to be kinetically controlled and could not be described by the solubility‐product relationship.
Pyrolysis‐Gas Chromatography‐Mass Spectrometry of Soil Humic Fractions: II. The High Boiling Point Compounds
Authors: Martin F. , Saiz‐Jimenez C. , Cert A. 
Published: July 2010

AbstractPyrolysis‐gas chromatography‐mass spectrometry studies of soil fulvic and humic acids were made. The high boiling point compounds produced by pyrolysis were separated in a column packed with Chromosorb AW DMCS 80–100 mesh coated with 10% FFAP. Humic acids with a high nitrogen content yielded a complex variety of protein derivatives, such as alkylpyridines, alkylpyrroles, alkylbenzonitriles, indoles, piperidines, pyrazines, and pyrrolidones. Humic acids with low N content yielded a smaller number of heterocyclic nitrogen compounds. Lignin derivatives were also identified, but the amount varied in different samples. Furanes were not as prominent as protein and lignin fragments. Acid hydrolysis released proteins, polysaccharides, and lignins, which could be considered as companion materials of a humic “core”. The majority of the pyrolysis compounds from the residue after hydrolysis were identified as alkylbenzenes, alkylnaphthalenes, phenols, benzofuranes, indenes, and fluorenes. Alkanes and alkenes were noted in trace amounts. Pyrolysis behavior of fulvic acids differed from that of humic acids. They produced poorly resolved pyrograms with smaller number and a lower intensity of peaks, from which only furfurals, phenols, benzofuranes, and naphthalenes could be identified.
Water‐Dispersible Soil Organic‐Mineral Particles: II. Inorganic Amorphous and Crystalline Phases in Density Fractions of Clay‐Size Particles
Authors: Spycher G. , Young J. L. 
Published: July 2010

AbstractWater‐dispersible clay‐organic particles from six epipedons and one Bh horizon were fractionated by density. After oxidation of organic matter in hydrogen peroxide, the amorphous particle phase was removed using a kinetic method and analyzed for Si, Al, and Fe. Light particles contained high levels of amorphous oxides and a poorly ordered phyllosilicate matrix. Heavy particles had low levels of amorphous oxides and a more crystalline matrix. A continuum in particle compositions and properties between the density extremes was observed and explained in terms of an aggregate model proposed in part I of the study.Molar silica to alumina ratios of the amorphous phase in particles ranged from 0.2 to 6.7. Low ratios (<1) occurred in particles from an Aquod Bh horizon and were attributed to organically complexed Al. The amorphous particle phase, mineral matter dissolving at a fast rate, was allophanic (low ratio) in two Andepts, and highly siliceous in an Argid. Intermediate ratios in other soils may have resulted in part from disordered phyllosilicates.
Prediction of Field Soil Water Content
Authors: Cameron D. R. 
Published: July 2010

AbstractA 3‐year experiment was conducted to monitor and subsequently predict field water contents using the water transport model. Saturated hydraulic conductivities and soil water characteristic curve results were measured and averaged for each soil layer. The Millington‐Quirk (MQ) method was used to calculate average model parameters. Direct use of the MQ‐derived conductivity and diffusivity functions did not give an exact fit to the observed field results. However, when reasonable adjustments were made to the K(θ) and D(θ) functions the prediction was improved considerably. The methodology for “averaging” and utilizing field data to derive model parameters, and subsequent adjustment or optimization of the model parameters all require more research if we hope to use the unsaturated flow equation for field water content prediction.