bluuebunny/crossref_metadata_2025_split huggingface dataset:
Soil and Rhizosphere Microorganisms in Amended Coal Mine Spoils
Authors: Fresquez P. R. , Lindemann W. C. 
Published: July 2010

AbstractTopsoil is usually respread over strip‐mined land during reclamation. In some instances, spoil could be used as a medium for revegetation. The objectives of this study were to compare microbial parameters in spoil and soil and determine the effect of spoil amendment on these microbial parameters.Representative samples from a topsoil stockpile, a nonvegetated spoil, a reclaimed area, and an adjacent undisturbed surface soil were collected from the San Juan coal mine near Farmington, N. Mex. Additional samples of spoil and stockpiled topsoil were used in a greenhouse pot experiment to determine the influence of spoil amendment on microbial parameters. The treatments included spoil, spoil plus topsoil inoculant, spoil plus alfalfa hay and fertilizer (both with and without topsoil inoculant), and spoil plus gamma‐irradiated sewage sludge (both with and without topsoil inoculant). The pots were planted to Bouteloua gracilis and microbial determinations of the spoil made after 5 months. Later the same pots were replanted to Atriplex canescens and microbial determinations made of the rhizosphere 7 months after planting. Microbial parameters measured included numbers of aerobic heterotrophic bacteria, Streptomyces, fungi, ammonium oxidizers, and aerobic asymbiotic nitrogen fixers, dehydrogenase activity, and fungal genera distribution.The undisturbed soil and reclaimed area had comparable microbial numbers, dehydrogenase activity, and fungal genera distribution. Microbial numbers and dehydrogenase activity of stockpiled topsoil and nonvegetated spoil were low and the fungal genera distribution was narrow.Topsoil inoculation did not increase microbial parameters of the spoil or of the rhizosphere of A. canescens. Spoils appeared to be unable to support an active and varied indigenous flora or the microorganisms introduced by the topsoil inoculant. Organic amendment of either sludge or alfalfa increased all microbial parameters. The increased numbers, dehydrogenase activity, and distribution of fungi were particularly evident in the rhizosphere. Providing an available carbon source was more critical in stimulating an active and varied spoil microflora than was supplying an inoculant source.
Statistical Analysis of Crop Yield Under Controlled Line‐source Irrigation
Authors: Bresler E. , Dagan G. , Hanks R. J. 
Published: July 2010

AbstractThe line‐source sprinkler irrigation system produces a water application pattern which is uniform along the length of the plot and variable across the plot. This ensures a high degree of uniformity of deterministic water application along strips parallel to the sprinkler line and minimizes effect of irrigation variability upon yield in such strips. Statistical techniques are applied to analyze yield results obtained from controlled line‐source field experiments. The spatial statistical structure of the crop yield is determined. The completely random component of yield is separated from the one displaying a spatial structure attributed to soil properties. Two of the three experimental fields considered display the complete random component solely, so that the usual statistical inference techniques are applicable. In one field the crop yield has a spatial statistical structure and the experimental plot seems to be smaller than the correlation scale, indicating that yield average and variance estimates depend on the size of the field. The main conclusions are: (i) statistical stationarity is achieved when yield is scaled with respect to its average for a constant irrigation level; (ii) soil variability has a large effect on yield; and (iii) the latter has a spatial structure which has to be inferred in order to carry out statistical analysis independent of field size.
Use of Circular Polarization on Soil Thin Sections to Distinguish Voids from Mineral Grains
Authors: Ruark G. A. , Veneman P. L. M. , Mader D. L. , Waldron P. F. 
Published: July 2010

AbstractApplication of crossed‐polarized (XP) light to thin sections of soil often results in images where the assessment of patterns of void distribution is complicated by the extinction of anisotropic mineral grains which have their optical axes exactly parallel to the plane of polarized light. A low cost system utilizing circularly polarized (CP) light rectifies this problem and is described in detail. Thirty‐three thin sections were photographed under both XP and CP light. The resulting 35‐mm color slides were examined with a Quantimet 720 Image Analyzer. A paired t‐test showed a highly significant reduction in void space estimates using CP light indicating a correction for mineral grain extinction. The photographs resulting from this method give consistent and accurate representation of parameters of voids regardless of sample orientation.
Effect of Grass, Legume, and Tree Roots on Soil Shearing Resistance
Authors: Waldron L. J. , Dakessian S. 
Published: July 2010

AbstractPlants enhance soil stability against downslope mass movement through the removal of soil water by transpiration and by the mechanical reinforcement of their roots. To assess the magnitude of this reinforcement, direct shear measurements were made on 0.25‐m diam cylindrical soil columns packed both homogeneously and in layers which simulated water and/or root‐impeding horizons. In all cases the matric potential was adjusted to zero before shearing. Twelve plant species were used including seven grasses: Phalaris tuberosa, Lolium rigidium, Dactylis glomerata, Bromus mollis, Sorgum bicolor sudanense, Triticum oestivum, Hordeum vulgare. Two legumes were used: Vicia dascarpa, Medicago sativa. and two trees were used: Pinus ponderosa and Quercus agrifolia.The ratio of the shear resistance at 25‐mm displacement of the rooted and unrooted specimens was used as a measure of root reinforcement. Roots of several grasses planted in early fall and sheared the following spring gave about a threefold increase in shear resistance at the 0.3‐m depth in homogeneous saturated clay loam. In the same material, roots of oak produced a similar increase only after 3 years' growth. One‐year‐old alfalfa produced a fourfold increase. At the 0.45‐m depth at the interface between soil and a dense gravel‐sand mixture simulating weathered rock, yellow pine gave a 1.5‐fold increase after 16 months and a 2.5‐fold increase after 52 months. Hardinggrass was almost equally effective after only 7 months.In almost all cases where roots increased soil shear resistance, the resistance continued to increase beyond 25‐mm displacement so that the selection of 25‐mm displacement was conservative, i.e., it may underestimate the root reinforcing effect.Factor of safety calculations for shallow planar slides using measured shear strengths show that plant roots can make large increases in slope stability.
Carbon‐13 Nuclear Magnetic Resonance Spectra of some Fungal Melanins and Humic Acids
Authors: Lüdemann H. D. , Lentz H. , Martin J. P. 
Published: July 2010

AbstractA study was made to compare the 13C‐NMR (Carbon‐13 nuclear magnetic resonance) spectra of a variety of fungal melanins with that of soil and Leonardite peat humic acids. The spectra were made in 5% wt/wt solution in 0.1N NaOD in D2O using the Fourier transform technique. All of the polymers gave complex 13C NMR spectra with strong signals, shoulders, or plateaus in the area of resonance for aliphatic, peptide, polysaccharide, aromatic, and carboxylic acid groups. The soil humic acid and all the original fungal melanins except that from Stachybotrys atra showed strong peaks or shoulders at about 20, 25, 28, 35, 40, 58, 75, 80, 110, 120, 130, 136, 175, and 180 ppm. The study gives further evidence that many fungal melanins are similar to soil humic acids in their chemical structure.
Lime Requirement Determination for Attaining pH 5.5 and 6.0 of Coarse‐textured Soils using Buffer‐pH Methods
Authors: Tran T. S. , van Lierop W. 
Published: July 2010

AbstractIn this experiment, we sought to verify the precision of the Shoemaker et al. (SMP), Yuan, Woodruff, and Mehlich lime requirement (LR) methods as proposed and modified for measuring the LR of 37 acid coarse‐textured soils to attain pHs 5.5 and 6.0. The SMP buffer was tried at initial buffer pH levels of 7.5, 7.0, 6.5, 6.0, and 5.5 as a single‐buffer (SB) method or double‐buffer (DB; McLean et al.) modification. Results indicate that linearity of the relationship between incubation LR and soil‐buffer pH increased as the initial buffer pH approached the desired soil pH. This comparison also disclosed that after recalibration the SMP‐SB method was as accurate and precise as the more complex SMP‐DB procedure for determining LR (5.5) and LR (6.0) rates. The most advantageous way of using the SMP‐SB method for determining these LR rates was with the customary initial buffer pH of 7.5 but calculating the prescribed rates with a curvilinear instead of the more common linear buffer calibrations.The Yuan buffer was evaluated at initial buffer pH levels of 7.0, 6.5, and 6.0 both with single‐ and double‐buffer methodologies. This comparison revealed that the Yuan‐DB procedure, though among the most precise tested for LR (6.0), was appreciably less precise for determining LR (5.5) rates. Nonetheless, the Yuan buffer was as precise for determining LR (6.0) rates and substantially more precise for prescribing LR (5.5) rates when used as a SB instead of its usually proposed more complex DB methodology.The Woodruff buffer was as precise as any for determining LR (6.0) rates, but its precision was substantially lower for LR (5.5). As proposed, the Mehlich method was probably the most accurate method tested for determining LR (5.5) rates, because this method prescribed on the average 111% of the incubation values and the prescribed and incubation values were closely related (r = 0.938**). This study revealed that most buffers can be used for determining LR (5.5) or LR (6.0) rates after appropriate calibration. Regression equations are, accordingly, provided for calculating or adjusting LR rates to pH 5.5 or 6.0 for the methods and modifications tested. Results also indicate that buffer calibrations are valid for a wider range of mineral soils than used in this study.
Use of Discriminant Analysis for Classification of Fertilizer‐Responsive Sites
Authors: Comerford N. B. , Fisher R. F. 
Published: July 2010

AbstractThe use of soil‐extractable phosphorus (P) was evaluated as a means for classifying P‐deficient soils. Two P extractants, ammonium acetate (pH 4.8) and double acid (Melich I), were employed as guides to P‐deficient soils. Surface soil‐extractable P was not useful for determining a P‐deficient site; however, either extractant, when used to a total depth of 60 cm, produced acceptable discriminatory power. The depth of soil sampling was as important or more important than the extraction used. Measurements of rooting depth such as drainage class and depth to a spodic horizon, argillic horizon, or mottles were useful variables for diagnosing nutrient‐deficient sites when combined with extractable P. The use of discriminant analysis in predicting fertilizer response is discussed.
A Timesaving Technique for Measuring Respiration Rates in Incubated Soil Samples
Authors: Edwards Nelson T. 
Published: July 2010

AbstractA method for determining CO2 efflux rates from large soil samples (50 to 200 g) is described. The method permits the measurement of cumulative CO2 efflux from large numbers of incubated samples in about 2 min/sample. The apparatus includes a CO2 scrubber, soil incubation jars, flow meter, drying column, dilution jar, and infrared gas analyzer. Results obtained using this method were less variable than results obtained with a Gilson differential respirometer when a homogeneous forest soil sample was tested.
Effects of Sawlog vs. Whole‐Tree Harvesting on the Nitrogen, Phosphorus, Potassium, and Calcium Budgets of an Upland Mixed Oak Forest
Authors: Johnson D. W. , West D. C. , Todd D. E. , Mann L. K. 
Published: July 2010

AbstractWhole‐tree harvesting increased the export of biomass N, P, K, and Ca by 2.6, 2.9, 3.1, 3.3, and 2.6 times, respectively, compared to sawlog harvesting in an upland mixed oak forest in eastern Tennessee. Whole‐tree harvesting after leaf fall reduced the potential drains of N, P, K, and Ca by 7, 7, 23, and 5%, respectively, compared with potential removal by harvesting during the growing season. Due to low soil Ca content and high Ca content in woody tissues, whole‐tree harvesting depleted total ecosystem Ca to a much greater extent than N, P, or K. Soil reserves and atmospheric inputs may be adequate to sustain total N, P, and K supplies with whole‐tree harvesting, but soil amendments may be necessary to sustain Ca supplies.
The Cross‐Coupling Transport Coefficient for the Steady Flow of Heat in Soil Under a Gradient of Water Content
Authors: Chu Shu‐Yuan , Sposito Garrison , Jury William A. 
Published: July 2010

AbstractA theoretical discussion based on the thermodynamics of irreversible processes (TIP) is given concerning the flux equations for the coupled, steady flows of water and heat in a soil as formulated by Jury and Miller. It is shown that a unique definition of the heat flux vector in a coupled flow process is not possible within the context of TIP alone, although differences between heat flux vectors can be defined uniquely. It is shown also that any set of coupled expressions for simultaneous, steady water and heat flow in soil that is compatible with TIP can be used to derive the Jury‐Miller formulation of the flux equations by means of linear transformations. Moreover, the cross‐coupling coefficient that links the heat flux to the gradient of water content vanishes identically in this formulation. However, a particular definition of the heat flux is implied by the Jury‐Miller equations and its relationship to the measured heat flux cannot be established solely by the methods of TIP. An examination of the data on heat and water flow reported by Jury and Miller indicated that the experimental sensitivity was not sufficient to discriminate among several alternative definitions of the heat flux that can be developed within TIP. This result serves to emphasize the point that the identification of the heat flux actually measured in a coupled flow experiment must be on the basis of either a theoretical model of the coupled flow processes or an application of the general equation of total energy balance.
Biodegradation, Stabilization in Humus, and Incorporation into Soil Biomass of 2,4‐D and Chlorocatechol Carbons
Authors: Stott Diane E. , Martin J. P. , Focht D. D. , Haider K. 
Published: July 2010

Abstract14C‐labeled catechol, 4‐chlorocatechol, and 4,5‐dichlorocatechol readily linked into model peroxidase humic acid‐type polymers, with 84 to 96% recovery of the 14C‐activity in the reaction mixtures. The 4,5‐Dichlorocatechol was the least reactive. 2,4‐D did not link into the polymers. The biodegradation of labeled catechol, 4‐chlorocatechol, and 4,5‐dichlorocatechol, free and linked into model polymers and of 2,4‐D, a fungal melanin, ferulic acid, wheat straw, and glucose were followed over 6‐month and 1‐year incubation periods in four soils, and the distribution of the residual activity in biomass, new humus, and 6N HCl hydrolyzable substrates was determined. The rate and extent of degradation depended upon the substrate, the concentration, and the soil. The 2,4‐D was rapidly degraded with 86 to 94% of the side chain and 73 to 85% of the ring‐14C evolved as CO2 over 1 year. Only 38 to 50% of the catechol, 22 to 63% of the 4‐chlorocatechol, and 22 to 62% of the 4,5‐dichlorocatechol carbons were lost over 1 year indicating substantial stabilization of these compounds, probably by enzymatic polymerization reactions. Catechol, 4‐chlorocatechol, and 4,5‐dichlorocatechol incorporated into model polymers were still more stable with 6 to 22, 8 to 42, and 13 to 43%, respectively, of the 14C evolved as CO2.After 1 year, about 3 to 8, 2 to 14, 1 to 7, 0 to 8, and 2 to 15% of the residual 14C activity from catechol, 4‐chlorocatechol, 4,5‐dichlorocatechol, the ring portion, and the side chain of 2,4‐D, respectively, was present in the biomass. The amount of residual C in the biomass from the catechols incorporated into the model polymers was very low and varied from 0 to 3%. The amounts of the residual 14C solubilized upon 6N HCl hydrolysis were related to the extent of biodegradation of the substrates. With highly degraded substrates, such as side chain 2,4‐D, glucose and wheat straw carbons the major portion of the residual C was lost upon hydrolysis. With highly resistant substrates such as catechol, the model polymers, and the fungal melanin, the major portion was not lost upon hydrolysis. The other substrates gave intermediate values.
Relationship of Topography to Soils and Vegetation in an Upper Michigan Ecosystem
Authors: Pregitzer Kurt S. , Barnes Burton V. , Lemme Gary D. 
Published: July 2010

AbstractThe influence of topography on soil development and classification and the interrelationships among soils and forest composition are poorly understood in Upper Michigan. Topographic plant‐soil interrelations are important because plants are increasingly being used to indicate environmental conditions and potential forest productivity. Our objectives, therefore, were to study the effect of topography on soil development and classification, soil nutrient status, and forest composition over a classical toposequence. An 8‐ha portion of a steep watershed was topographically mapped, and soils and plants were sampled and analyzed using established techniques. In addition, the distributions of selected ground flora species were mapped over the landscape. Results indicate a strong correspondence between the distribution of plants, soil development and classification, and soil nutrient status. Soils ranged from a Lithic Dystrochrept in the upper slope through a Typic Dystrochrept, Entic Haplorthod, Dystric Eutrochrept, and finally a Terric Borosaprist in the toeslope; this is considerable variability within a horizontal distance of 300 m. Soil nutrient status varied along with soil development and was strongly related to topographic position. For these coarse‐textured soils, increased content of macronutrients is closely associated with increased content of soil organic matter. For example, in the surface soil of a colluvial soil profile we found that soil nitrogen was roughly 10 times greater than in the subsoil; this large difference in soil nitrogen was closely associated with large amounts of soil organic matter in the surface soil. Within the highly variable landscape, forest composition followed variability in soil development, soil organic matter, and soil nutrient status. Groups of ground flora species were closely associated with these soil and topographic variations.
Mineralogy of Saudi Arabian Soils: Central Alluvial Basins
Authors: Viani B. E. , Al‐Mashhady A. S. , Dixon J. B. 
Published: July 2010

AbstractThese investigations were conducted to provide basic soil chemical, physical, and mineralogical data for an area of Saudi Arabia that had not been studied and for which greatly increased agricultural development is anticipated. Fourteen soils were collected from two arid interior basin areas of Saudi Arabia. The silt and clay mineralogy was studied using x‐ray diffraction, differential thermal analysis, and electron microscopy. Quantitative estimation of clay‐sized minerals was based on a combination of chemical and x‐ray diffraction techniques. The calcareous soils of the central basins show minimal profile development. Particle‐size classes range from sandy‐skeletal to fine silty. Soils with shallow water tables are saline with large SAR values. The clay minerals in soils of the basins are primarily inherited. Soils developed in alluvium from mixed igneous rocks have clay fractions in which smectite > mica > kaolinite > chlorite, palygorskite, vermiculite. Soils formed from Permian sedimentary rocks have kaolinitic clay fractions. It is postulated that the central basins do not receive sufficient Si inputs for palygorskite neoformation and it is though that palygorskite is detrital, originating from easternregion Tertiary rocks. The soil clays of the central hasins have greater smectite contents than those of the kaolinitic western highland soils and palygorskite‐rich eastern‐region soils.
Transformation of Smectite to Kaolinite in Naturally Acid Soil Systems: Structural and Thermodynamic Considerations
Authors: Karathanasis A. D. , Hajek B. F. 
Published: July 2010

AbstractFour acid montmorillonitic soil profiles were sampled to study thermodynamic‐stability relationships and chemical weathering of soil minerals. Solid‐ and solution‐phase characterization indicated smectite to be the metastable precursor of kaolinite with the highest rate of transformation occurring in topsoil horizons. Structures of Al‐saturated smectites were found to be nonideal with respect to excess structural OH‐ water and below normal (≈550°C) dehydroxylation temperatures. Structural and thermochemical data suggested the weathering sequence was montmorillonite → beidellite → kaolinite. The smectite → kaolinite transformation appears to be a combination of dissolution‐precipitation and structural reorganization processes. Excess structural OH‐ in the beidellitic structure seems to have played a key role in the transformations. Montmorillonite → beidellite and beidellite → kaolinite transformations were favored in the more weathered topsoil horizons where solutions were undersaturated with respect to amorphous SiO2. Kaolinite precipitating from supersaturated solutions appeared to have a range in crystallinity and standard free energy of formation (ΔGof), approaching those of halloysite at high solution silica activities.
Experimental Verification of a Model to Predict Soil Moisture and Temperature Profiles
Authors: Lascano R. J. , van Bavel C. H. M. 
Published: July 2010

AbstractA model was used to calculate water and temperature profiles over 30 d for a bare soil profile, using the hydraulic characteristics of the soil and standard meteorological data as input. The model was also used to determine the spatial variability of the calculated values, using the concept of similar media. The calculated profiles were compared to actual measurements, made periodically over the same period of time. The predicted water content values for different soil layers were within 1 standard deviation of the average measured values. The predicted temperature profiles were within 1° C of the measured values. The estimate of the spatial variability of the calculated values of water content was comparable to the variance of the measured values. Hence, it is concluded that the model was adequate to its purpose, under the conditions of the verification made.
A Comparison of Diffusion and Distillation Methods for Preparing Samples for 15N Analyses
Authors: Adamsen F. J. , Reeder J. D. 
Published: July 2010

AbstractThis study was conducted to compare a distillation method with tube diffusion for the preparation of samples for 15N analyses. Standard samples [1 mg of N as (NH4)2SO4] with various 15N excess contents (0, 3, or 10 atom % excess 15N) were distilled or diffused and compared with nondiffused, nondistilled standards. There were no significant differences between treatments at the 0% level of enrichment. However, at the 3 and 10% levels of enrichment, both distilled and diffused standards were significantly lower than the nondistilled, nondiffused standards. No significant differences (p < 0.05) were found between HCl and H2SO4 as trapping solutions. The data indicate that diffusion is an acceptable alternative to distillation, since the 15N values are comparable and the precision is slightly better.