bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nitrogen Mineralization and Nitrification: Depth Variation in Four New England Forest Soils
Authors: Federer C. A. 
Published: July 2010

AbstractNet nitrification and net nitrogen mineralization over 1 midsummer month were measured by in‐situ incubation at 14 depths in a single pit in each of four mature forest stands in New England. Nitrogen mineralization per unit of organic mass was greatest in the Oe horizon in two New Hampshire soils and in the upper A horizon in a Connecticut soil, and generally declined with increasing depth. In a Maine soil mineralization per unit of organic mass was independent of depth. Mineralization ranged from 2 to 14 kg N·ha−1 for 28 d in the four forest floors and from 3 to 12 kg N·ha−1 in the four mineral soils. Nitrification was not detected in any forest floors, but was 0.1 to 3.3 kg N·ha−1 for 28 d in the mineral soils. Both the large variation with depth and the contribution of mineral soil should not be overlooked when studying these processes.
The Effective Removal of Suspended Materials from Pyrophosphate Extracts of Soils from Tropical and Temperate Regions
Authors: Schuppli P. A. , Ross G. J. , McKeague J. A. 
Published: July 2010

AbstractSodium pyrophosphate (0.1M) extracts of some soil samples from Canada and East Malaysia were subjected to low‐speed centrifugation both without and with Superfloc, high‐speed centrifugation, and ultrafiltration of the centrifugates prior to determination of their Fe and Al contents. Relative to ultrafiltration, none of the centrifugation methods cleared the extracts completely and thus part of the extracted Fep and Alp measured in the supernatants was present in suspended solids. Suspended solids, with mineralogy similar to that of the clay of corresponding samples, were particularly abundant in the supernatants of the tropical soil samples after low‐speed centrifugation without Superfloc. Adding Superfloc to these extracts and centrifuging them at low speed sedimented practically all the aluminum silicates but concentrated the goethite in the material that remained suspended. High‐speed centrifugation gave similar results but with less concentration of goethite. Smaller amounts of suspended solids, also with mineralogy similar to that of the clay of corresponding samples, were present in the supernatants of samples from Canadian soils, except for that from a spodic horizon sample in which suspended minerals were absent. Ultrafiltration of the centrifugates through a 0.025‐µm millipore filter cleared the extracts effectively and is recommended for tropical soils and for soils giving doubtful results with centrifugation methods only. High‐speed centrifugation is probably adequate for most temperate‐region soils, as suspended Fe and Al in the extracts tested accounted for 0.1 dag/kg or less of sample weight.
The Persulfate Oxidation of Fungal Melanins
Authors: Martin F. , Gonzalez‐Vila F. J. , Martin J. P. 
Published: July 2010

AbstractFour fungal melanins were degraded by potassium persulfate, a new, mild chemical oxidation method. The percentage of degradation varied from 15 to 50% calculated by weight loss. Analysis of the degradation products by gas chromatography showed numerous fatty acids, both straight and branched chain, in widely varying amounts. The n‐C16 and n‐C18 acids were present in greatest abundance. By two‐dimensional thin‐layer chromatography, several phenols and anthraquinones were noted.
Characteristics of Rhizobium trifolii Populations Associated with Subclover in Mississippi Soils
Authors: Hagedorn C. , Ardahl A. H. , Materon L. A. 
Published: July 2010

AbstractIndigenous Rhizobium trifolii populations that would nodulate Trifolium subterraneum L. (cv. Mt. Barker) were isolated and characterized from pastures with and without subclover in five distinct soil regions in Mississippi. Considerable variation in effectiveness was found among isolates from the different areas and from individual sampling sites within areas, and the combined results indicated that subclover production and soil fertility levels were related and were being better maintained within two of the sampling areas. Pastures without clover yielded small R. trifolii populations that were poorly effective in N fixation on subclover. Significant correlations were found between the Rhizobium population size and soil N levels, soil texture, organic matter content, and exchangeable acidity. Isolate effectiveness was associated with the amount of base saturation, soil acidity, and N levels. These results are discussed in the context of subclover production as related to Rhizobium effectiveness, population size, and soil fertility characteristics.
Soil Fertility Dynamics after Clearing a Tropical Rainforest in Peru
Authors: Sanchez P. A. , Villachica J. H. , Bandy D. E. 
Published: July 2010

AbstractThis paper describes changes in soil properties during the first 8 y after clearing a fine loamy, siliceous, isohyperthermic Typic Paleudult at Yurimaguas, Peru. Three adjacent fields under a 17‐year old secondary forest were slashed, burned, and planted to three crops per year with or without fertilization for 8 years. Ash from the burn increased soil pH, available N, P, K, Ca, Mg, and decreased exchangeable Al. Six months after burning, however, the levels of available N and K were reduced, along with sporadic S, Cu, and B deficiencies. Topsoil organic C and total N decreased at an annual rate of 25% during the first year but approached an equilibrium afterwards. The rapid organic matter decomposition probably released organic matter‐bound Al which reversed the liming effect of the ash. Phosphorus and Mg became deficient during the second year, Ca within the first 30 months and Zn and Mn during the fourth year. Molybdenum deficiencies occurred sporadically, particularly when locally produced legume seed was used. Soil chemical properties have improved with continuous cultivation because of liming and fertilizer additions. After 8 years and 21 crops, topsoil pH increased to 5.6, exchangeable Ca increased by 10 times, effective CEC doubled, available P increased from 5 to 39 mg kg−1, and Al saturation decreased from 82 to 1%. The 15‐ to 50‐cm layer of the subsoil has undergone significant increases in exchangeable Ca and Mg and a decrease in Al saturation. This should promote deeper root development. The time at which nutrient deficiencies appeared and the amounts of fertilizer or lime needed to correct them varied substantially between the three fields, despite their close proximity, same preclearing vegetation, geomorphic position, and same soil classification at the family level.
Color Patterns and Water Table Levels in Some Indiana Soils
Authors: Franzmeier D. P. , Yahner J. E. , Steinhardt G. C. , Sinclair H. R. 
Published: July 2010

AbstractIn soils of sandy, coarse loamy, fine loamy, fine silty, and fine particle‐size families, we observed some general relationship between water table depths and soil color pattern. Horizons that have dominantly gray (chroma ≤ 2) color in the matrix or argillans are saturated much of the year. Horizons that have gray mottles, but are dominantly brown, are saturated a few months of the year if they are above the dominantly gray horizons, or are saturated most of the time if these horizons are below the dominantly gray horizon. Horizons that have dominant chroma of three in the matrix, mottles, or argillans are often saturated. Those that have dominant chroma of five or six and have no mottles with chroma of three or less are seldom or never saturated. This study shows that soils with three‐chroma matrix, mottles or argillans are much wetter than they had been thought to be and are wetter than reflected in Soil Taxonomy definitions.
Evaluation of Manual Cadmium Reduction Methods for Determination of Nitrate in Potassium Chloride Extracts of Soils
Authors: Dorich R. A. , Nelson D. W. 
Published: July 2010

AbstractAlthough 2M KCl is widely used as an extractant for inorganic N in soils, most colorimetric NO‐3 methods are not applicable to such extracts. Keeney and Nelson (1982) have recently described a Cd reduction procedure for determination of NO‐3 in KCl extracts that was adapted from those used for water analysis. Other published manual Cd reduction methods may be applicable to analysis of KCl extracts of soils. The objectives of this work were to determine the conditions necessary for quantitative reduction of NO‐3 on the Cd column and to evaluate the applicability of Cd reduction procedures for the determination of NO‐3 in KCl extracts. Studies indicated that slower eluant flow rates and/or longer Cd columns than those specified in the Keeney and Nelson method resulted in nonquantitative recovery of added NO‐2 and NO‐3 due to destruction of NO‐2 by the Cd column. These findings indicated that the Keeney and Nelson method was the manual Cd reduction procedure best suited for analysis of KCl extracts. Nitrate added to 2M KCl extracts of soils was quantitatively recovered by the Keeney and Nelson method. The coefficient of variation for the method ranged from 2.1 to 3.4% when KCl extracts were analyzed over 3 d. Analysis of NO‐3 in 2M KCl extracts of soils established that the Cd reduction method gave values similar to those obtained by a steam distillation‐acidometric titration procedure and markedly higher that those with a brucine colorimetric technique. After KCl extracts had been prepared, approximately 36 samples could be analyzed per hour by the Keeney and Nelson procedure. The manual Cd reduction method using a 110 mL min−1 flow rate and a 20‐cm column is a rapid, precise, and accurate technique for determination of NO‐3 in KCl extracts of soils.
Evaluation of the Ammonium Bicarbonate‐DTPA Soil Test for Assessing Boron Availability to Alfalfa
Authors: Gestring W. D. , Soltanpour P. N. 
Published: July 2010

AbstractThe NH4HCO3‐DTPA (AB‐DTPA) soil test of Soltanpour and Schwab was developed to simultaneously extract plant‐available P, K, Zn, Fe, Cu, and Mn. The extractant consists of 1.0M NH4HCO3 and 0.005M DTPA adjusted to pH 7.6. Although the AB‐DTPA soil test was developed primarily to extract the previously mentioned nutrients, its use for determining plant availability of other nutrients may be feasible. The objective of this study was to evaluate the AB‐DTPA soil test for determining plant‐available B.Seven soils from Colorado which varied in texture and organic matter content were treated with sodium borate (Na2B4O7·10H2O) at 0, 1, 3, 5, and 10 µg B/g soil. Alfalfa (Medicago sativa var. ‘Ladak’) was planted in the soils in the greenhouse and then cut three times at the 30% bloom stage. Plant tissue digests and soil extracts (AB‐DTPA, hot‐water, saturation) were analyzed for B using inductively coupled plasma atomic emission spectroscopy (ICP‐AES).Saturation and AB‐DTPA extractable B levels were nearly identical while the hot water soil test extracted significantly (α = 0.05) higher amounts of B. Alfalfa yields were not significantly (α = 0.05) affected by increasing B application rates indicating B deficiency and toxicity conditions were not present.Plant B was highly correlated to all three extractants for the individual soils; however, the coefficients of determination (r2) for plant B and soil B differed appreciably when the pooled soils were analyzed statistically: r2 = 0.51 for AB‐DTPA, r2 = 0.87 for hot water, r2 = 0.76 for saturation extract, indicating the superiority of the hot‐water extractant for B. Multiple linear regression analysis also indicated the superiority of the hot‐water extractant and denoted that NH4HCO3‐DPTA soil test required the addition of soil variables (soil pH, % OM, % clay) to be considered an effective test.
Sulfur Nutrition of Rapeseed: I. Influence of Fertilizer Nitrogen and Sulfur Rates
Authors: Janzen H. H. , Bettany J. R. 
Published: July 2010

AbstractBoth sulfur and nitrogen deficiencies have been observed in large acreages of western Canadian soils. These deficiencies prompted an investigation of the interactive effects of N and S on rapeseed (Brassica napus L.), a S‐sensitive crop that is extensively grown on these soils. Four rates of N (0, 50, 100, 300 mg N kg−1 soil) and four rates of S (0, 5, 15, 40 mg S kg−1 soil) were applied in all combinations to rapeseed grown in a pot culture experiment. Maximum seed yield responses to N and S were observed only when the availability of N and S was in approximate balance. Excessive N applications relative to S availability severely suppressed seed production. This effect was attributed to the accumulation of toxic levels of N metabolites. Excessive S applications relative to N availability produced excessive accumulation of S in the plant tissue. The leaves, and, to some extent, the stems, were the predominant sites of excess nutrient accumulation. Seed nutrient concentrations remained relatively stable over all fertilizer treatments. In most plant parts, the applications of one element reduced the concentrations of the other element by a “dilution” effect. The optimum ratio of available N to available S in the soil was estimated to be 7 to 1. Ratios below 7 resulted in inefficient utilization of the assimilated S, while ratios exceeding 7 resulted in reduced seed yields.
The Relationship of Present Topography to Pre‐Loess Deposition Topography in Eastcentral Ohio
Authors: Norton L. Darrell 
Published: July 2010

AbstractPrevious work in Ohio has shown that loess deposition over glacial till smoothed the underlying topography considerably, resulting in a highly variable loess thickness. In this study, loess thickness and other soil properties were measured on an erosional landscape system and were presented by contour maps and three‐dimensional diagrams. The shape of the modern surface was very similar to the shape of the paleolandscape, so the loess thickness did not smooth the old surface very much. The uniform thickness of the loess allowed the amount of soil material removed from the landscape units studied to be calculated. Depending on the assumed age of loess deposition, the rate of geological erosion ranged from 0.035 to 0.060 Mg ha−1 yr−1 for this summit and shoulder position. The thickness of the fragipan was highly correlated with slope position and was more strongly developed on the shoulder positions. Studies such as this one, where depth measurements of soil properties are made at many points in a landscape and where the data is represented in three‐dimensional diagrams will lead to a better understanding of processes, such as erosion, that depend greatly on landscape position.
Predicting Soil Temperature and Soil Heat Flux under Different Tillage‐Surface Residue Conditions
Authors: Gupta S. C. , Larson W. E. , Allmaras R. R. 
Published: July 2010

AbstractModel descriptions for soil temperature utilizing readily available information are needed to project management effects of tillage. In many cases these model descriptions must cover periods of a month or more during the growing season. A procedure was developed to utilize daily maximum and minimum air temperature along with normalized root zone temperatures. Root zone temperatures were much more sensitive to the surface residue than the surface roughness (or other tilled layer property) characteristic of tillage‐residue cover combinations. However, root zone temperatures normalized with respect to daily maximum and minimum temperatures were of a similar shape for all tillage‐residue cover combinations. These normalized soil temperatures also afforded easy comparison among treatments and locations. A Fourier series analysis of daily normalized soil temperatures averaged over part of a growing season showed that the average value around which average normalized soil‐temperature curves (diurnal wave) oscillate varies with depth and season. Amplitudes and phase angles of the first two harmonics of the Fourier series were approximately the same for all treatments over four seasons.A model was developed to estimate soil temperatures for various tillage‐residue cover treatments with and without a crop cover for the northern Corn Belt states. The model utilizes the first two harmonics of the Fourier series and the relationships between the daily maximum and minimum soil surface temperatures vs. maximum and minimum air temperatures. Input needed for the model are: daily maximum and minimum air temperatures, thermal diffusivity of soil, and coefficients of the Fourier series fitted to average normalized soil temperatures. At one location in southern Minnesota the model predicted soil temperatures at 0.05 and 0.10‐m depths over 45 d during the spring of 1980 within an average difference of 2.0°C and a deviation of no more than 3.8°C 67% of the time.A procedure to estimate hourly soil surface heat flux under different tillage and residue conditions is also presented. The procedure is based on the Fourier series soil temperature model. Inputs needed for the model are: (i) daily maximum and minimum air temperatures, (ii) thermal diffusivity, and (iii) volumetric heat capacity. Soil surface heat flux is often needed in the calculation of evaporation from the energy budget methods.
The Effects of Texture on the Resistance to Water Movement within the Rhizosphere
Authors: Bristow K. L. , Campbell G. S. , Calissendorff C. 
Published: July 2010

AbstractA growth chamber study was designed to investigate the relative importance of the resistances involved in water movement within the rhizosphere. The components considered are the soil, the soil‐root interface, and the root itself. The plant species used was sunflower (Helianthus annus L.), grown in three soils of different texture. After several weeks of growth all water application was stopped and the soil allowed to dry by transpiration alone. Relevant destructive measurements were carried out during the course of the drying period, one pot being sacrificed for each set. Measurements included transpiration rate, soil and xylem water potential, rooting density, and hydraulic properties of the soils. As the soil dried, total resistance to water movement was found to increase most rapidly in the coarsest textured soil and least rapidly in the finest textured soil. A steady state model was used to partition the total resistance between the various resistive components. This enabled the root plus interfacial resistance to be quantified in terms of soil texture and water content.
Measurement of Inverted Electrical Conductivity Profiles Using Electromagnetic Induction
Authors: Corwin D. L. , Rhoades J. D. 
Published: July 2010

AbstractDue to sharp discrepancies in the relative response of the horizontal and vertical coil configurations of the Geonics Limited EM‐38 electromagnetic induction soil conductivity meter for the top 15 cm of soil, the accuracy of measurement of bulk electrical conductivity for soil having a high surface electrical conductivity relative to deeper depths (i.e., an inverted electrical conductivity profile) has been unreliable. Two new approaches have been developed to compensate for these discrepancies, either through compensations in the vertical coil configuration response curve or the reestablishment of EM0,H adjustment curves utilizing data solely from inverted conductivity profiles. Both approaches yield more consistently reliable calculated bulk soil electrical conductivities when compared to measured electrical conductivities using the four‐electrode probe. The latter approach, however, appears to be more accurate.
Physical Transformations in a Vertical Soil‐Saprolite Sequence
Authors: O'Brien E. L. , Buol S. W. 
Published: July 2010

AbstractA continuous vertical soil‐saprolite‐granitic gneiss profile was studied to determine its morphology, micromorphology, and physical properties. A clayey, kaolinitic, thermic Typic Hapludult formed in 4.5 m of saprolite derived from a granitic gneiss was sampled in 14 different levels from the surface to the consolidated rock to determine changes with depth. Morphologically, the Piedmont soil has a gravelly sandy loam surface over a red, clayey, moderately structured subsoil. The saprolite has a 1.15 m transitional sandy clay loam horizon over 3.35 m of a sandy loam saprolitic material with rock controlled structure overlying consolidated rock. Micromorphologically, content of skeletal grains increases with increasing depth in the subsoil and saprolite. Plasma and compound void volume decrease with increasing depth. Bulk density measurements of 0.95 Mg m−3 are found in the soil surface, 2.46 Mg m−3 in the rock, and about 1.3 Mg m−3 in the subsoil and saprolite. Pore size distribution as indicated by soil moisture release measurements shows 40% more macroporosity in the subsoil than the saprolite. Saturated hydraulic conductivity in the subsoil is 2.2 µm s−1—over twice the 1.1 µm s−1 found in the upper saprolitic horizon. Theoretically derived unsaturated hydraulic conductivities show little difference between the subsoil and saprolite. The significant physical changes accompanying the weathering of this saprolite to soil include: a weathering of sand‐sized weatherable minerals to clay‐sized minerals, an increase in structural strength of the Bt horizon, an accompanying increase in macroporosity in the Bt horizon, and higher saturated hydraulic conductivity in the Bt horizon than in the saprolite.
Temperature and Moisture Regimes in Soils Mulched with Transparent Polyethylene
Authors: Mahrer Ytzhaq , Naot Ofir , Rawitz Ernest , Katan Jaacov 
Published: July 2010

AbstractA numerical one‐dimensional model was developed in order to study the effect of soil mulching with transparent polyethylene film upon the soil moisture and temperature regimes. Environmental conditions, soil physical characteristics, and optical properties of the cover are considered. Calculated moisture and temperature profiles were compared with observed ones in experimental field plots. It was shown that soil moisture and temperature distributions are significantly influenced by the polyethylene mulch. The results indicate that the numerical model accurately predicts the soil moisture and temperature regimes in two tested soils. In both a Rehovot sand soil and a light clay soil, experimental and calculated results showed that the temperature maxima of the soil increase with increasing soil moisture content. In the light clay soil both the experimental and numerical results showed that the tarping of the soil with transparent polyethylene caused a significant increase in soil moisture in the upper soil layer. At close to air‐dry moisture content, the maximum temperature of the light clay soil indicated a much higher value than the wettest mulched plot of the same soil. Physically based explanations are given for the measured and computed results.
Development and Calibration of an Irregular Hole Bulk Density Sampler
Authors: Flint Alan L. , Childs Stuart 
Published: July 2010

AbstractExisting methods for measuring soil density and rock fragment content are often imprecise or difficult to use on steep slopes and in skeletal soils. A portable device was developed for measuring these physical properties using an irregular hole technique. The method employs a direct volume measurement using lightweight 3‐ to 6‐mm diameter epoxy spheres. A sample volume of 1.5 × 10−2 m3 can be measured and rock fragments up to 85 mm in diameter can be sampled. The combination of direct volume measurement and surface calibration before measurement allows determination of sample volume to 1% accuracy. Measurements made with the new device compare well with sand cone and core sample measurements under conditions considered favorable for all methods. The device is particularly useful on steep slopes and where rock fragment contents greater than 15% limit the standard methods.