bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tillage Influence on Soil Sulfur Characteristics in Winter Wheat‐Summer Fallow Systems
Authors: Tracy P. W. , Westfall D. G. , Peterson G. A. , Elliott E. T. 
Published: July 2010

AbstractConversion of native prairie ecosystems to crop production leads to net losses of many essential plant nutrients. The purpose of this research was to monitor winter wheat (Triticum aestivum L.)‐fallow rotations for seasonal soil S fractions and S dynamics as affected by tillage. Soil samples from plots that had been subject to 15 yr of no‐till, stubble mulch, and conventional tillage were collected at monthly (cropped) and 2‐wk (fallow) intervals, from May through October at depth increments of 0 to 2.5, 2.5 to 5, 5 to 15, 15 to 30, and 30 to 60 cm. Sulfate‐S, carbon‐bonded S (CB‐S), and esterbonded S (HI‐S) concentrations were determined for each soil sample. During fallow, SO4‐S accumulation in the surface 0 to 5 cm was 1.5 times greater in no‐till than in tilled soils. After a rainfall of 49 mm, SO4‐S concentrations increased at 15 to 30 cm from 4.6 to 5.8 mg kg−1 in no‐till, 3.1 to 8.3 mg kg−1 in stubble mulch, and 3.4 to 11.2 mg kg−1 in plow treatments. No‐till soils contained higher amounts of HI‐S at 0 to 15 cm than either tilled soil. There was no difference in CB‐S concentration at 0 to 15 cm between no‐till and stubble mulch with both containing higher CB‐S contents than plowed soils. Lower surface concentrations of SO4‐S, greater SO4‐S leaching, and lower HI‐S and CB‐S in tilled than in no‐till soils indicates that S is conserved in low‐soil‐disturbance tillage systems.
Soils and Mineral Weathering on Phyllite Colluvium and Serpentinite in Northwestern California
Authors: Graham R. C. , Diallo M. M. , Lund L. J. 
Published: July 2010

AbstractHaplohumults and Argixerolls have formed in close proximity on phyllite colluvium and serpentinite residuum, respectively, in the Klamath Mountains of northwestern California. This study was conducted to compare their contrasting properties and to investigate soil mineral weathering. Thick, dark A horizons containing 20 to 50 g kg−1 organic C have formed in the Argixeroll under the influence of perennial grass cover with sparse conifers and shrubs. The Haplohumult, under dense Douglas fir [Pseudotsuga menziesii (Mirbel) Franco] forest, has a thin A horizon containing 10 to 20 g kg−1 organic C. Soil pH is in the range of 5.6 to 5.8 in the A horizons of both soils. In the Haplohumult, pH decreases slightly with depth, whereas pH increases to 6.5 in the Crt horizon of the Argixeroll. The mineralogy of the Haplohumult is relatively uniform throughout its 260‐cm depth. Chlorite, the dominant mineral in the phyllite parent rock, has altered to interstratified chlorite/vermiculite and poorly crystalline kaolin in the soil fine‐sand fraction. Chlorite/vermiculite and kaolin dominate the clay fraction, accompanied by gibbsite, talc, and Fe oxides. Serpentine weathering prevails in the Argixeroll. The serpentine content of the fine‐sand fraction decreases upward in the profile, whereas magnetite and chlorite resist weathering and are concentrated. Serpentine is the most abundant mineral in the clay fraction. Clay‐size smectite, a product of serpentine weathering, is absent from A horizons, but increases with depth to a maximum in the fine‐earth material from cracks in the Crt horizon. Chlorite in the clay fraction is inherited from the parent rock. Both soils have experienced minor surficial additions of amorphous silica phytoliths and volcanic glass shards.
Regional and Catenary Variations in Properties of Borolls of Southern Saskatchewan, Canada
Authors: Pennock D. J. , de Jong E. 
Published: July 2010

AbstractThe spatial pattern of soil properties results from systematic variations in the type and intensity of soil‐forming processes and from random variations superimposed on the systematic variations. We examined the thickness of A horizons and depths to CaCO3 at 21 sites in southern Saskatchewan to determine whether systematic differences occurred among soil‐moisture regimes of Borolls and among landform elements in catenas. The mean thickness of A horizons was thinnest for the aridic Borolls (x̄ = 15.3 cm) and ustic Borolls (x̄ = 15.2 cm) and thickest in the udic Borolls (x̄ = 18.4 cm), reflecting the regional moisture gradient. The regional differences in mean depth to CaCO3 were contrary to the expected pattern: mean depths were smallest for the ustic Borolls (x̄ = 29.9 cm) and greatest for the aridic (x̄ = 34.1 cm) and the udic (x̄ = 34.9 cm) Borolls. A consistent pattern was associated with landform elements in soil catenas. The smallest means for both properties were associated with shoulder and backslope elements with convex across‐slope curvatures, and the greatest means for footslope elements with concave across‐slope curvatures. The range in mean values of the two properties among landform elements within a catena was consistently an order of magnitude greater than the regional differences among soil subgroups.
Simulated Erosion and Fertilizer Effects on Winter Wheat Cropping Intermountain Dryland Area
Authors: Massee T. W. 
Published: July 2010

AbstractTopsoil loss from erosion in the intermountain dry‐farming area reduces crop yields. This study tested the hypothesis that the effects of erosion on water storage and wheat (Triticum aestivum L.) yield could be partially alleviated by applying appropriate fertilizers. Two sites were used, one on Rexburg silt loam, a coarse‐silty, mixed, frigid Calcic Haploxeroll, and the other on Newdale silt loam, a coarse‐silty, mixed frigid Calciorthidic Haploxeroll. Topsoil‐depth treatments were +15, 0, −15, or −30 cm changes relative to the original surface. After making the soil depth changes, 54 kg P ha−1 were incorporated on one half of each topsoil depth plot and the other half received no P. These P or no P plots were split for applications of 0, 34 or 68 kg N ha−1. Phosphorus had no effect on wheat yield. Without fertilizer N, yields on −15 and −30‐cm plots were reduced 46 and 55%, respectively, but increased 69% from the addition of 15 cm of topsoil, compared with the 0‐cm plot. Removing 15 and 30 cm of topsoil also reduced the upper limit of N‐fertilized production to 80 and 65%, respectively, of production on undisturbed N‐fertilized plots. Three kilograms fertilizer N ha−1 each crop year offset each centimeter of soil removed, but only to the new lower production limit. All plots had similar amounts of stored, available soil water in the spring, but a large fraction of this water remained unused at harvest on plots with 15 and 30 cm of topsoil removed because the low‐yielding wheat did not use as much water. Profile water differences at harvest were no longer apparent by the next spring, following winter recharge. Unused water at harvest, which partially filled the soil profile, reduced winter infiltration and contributed to subsequent runoff from precipitation on those plots. Adding N fertilizer was only a partial solution to topsoil deficiencies.
Cation Removal during Application of Acid Solutions into Air‐Dry Soil Columns
Authors: Liu K. H. , Mansell R. S. , Rhue R. D. 
Published: July 2010

AbstractAcidic deposition is considered an environmental problem that may be modifying the forest soil, and that affects the forest soil's cation‐exchange status. The primary purpose of this study was to determine whether cation removal from laboratory columns of Cecil soil (a clayey, kaolinitic, thermic Typic Kanhapludult) would be proportional to the proton concentration of the acidic input solution. A second purpose was to find the effective‐charge balance of major cations in the soil columns after termination of acid infiltration. Aqueous HCl solutions of pH 3.9 and 4.9 were applied with constant flux to columns of initially air‐dry topsoil and subsoil until approximately 30 pore volumes of effluent had been collected. Larger quantities of cations were leached by the pH 3.9 solution. The ratio of cations removed in the two cases was considerably less (<2‐fold) than the 10‐fold H ion ratio of the two input acid solutions. The effective‐charge balance error of major cations was greatest for the high‐pH solution. Differences in effective‐charge balance of major cations were greater for columns of subsoil than for topsoil. Application of acid (HCl) solutions definitely accelerated leaching losses of cations from the forest Cecil soil.
Effects of Urea‐Potassium Chloride and Nitrogen Transformations on Ammonia Volatilization from Urea
Authors: Gameh M. A. , Angle J. S. , Axley J. H. 
Published: July 2010

AbstractAmmonia volatilization following fertilization with urea can be substantial. Losses via NH3 volatilization may be reduced with the concurrent application of KCl, which temporarily reduces soil pH. The objective of this study was to examine the influence of various urea‐KCl mixtures on NH3 volatilization and N transformations in two soils. Urea, granular urea plus KCl, urea plus KCl in solution, and urea coated with powdered KCl were added to a Matapeake silt loam (a fine‐loamy, mixed, mesic Typic Hapludult) and a Hagerstown silty clay loam (a fine, mixed, mesic Typic Hapludalf) at rates equivalent to 260 kg urea ha−1 (120 kg N ha−1) and 260 kg KCl ha−1 (135 kg K ha−1). During the first 13 d of incubation in the Matapeake soil, 26% of the N applied as urea alone was lost via NH3 volatilization. From the KCl‐coated urea, only 13% of the applied N was lost via volatilization. Ammonia losses from the Hagerstown soil were less than from the Matapeake soil but were still significantly reduced by the KCl coating on urea. Differences in NH3 volatilization between the soils were primarily attributed to the rate of urea hydrolysis and subsequent N transformations. These results indicate that coating urea with KCl may offer a significant advantage over uncoated urea, especially in K‐deficient soils.
New Technique for Measuring Volumetric Shrinkage in Soils
Authors: Overby Steven T. , DeBano Leonard F. 
Published: July 2010

AbstractVolumetric shrinkage in soils is an important physical parameter used in soil erosion and soil mechanics studies. The American Society for Testing Materials D427 method for determining volumetric shrinkage was modified using a less toxic silicone‐mineral spirits mixture instead of liquid Hg. The silicone‐mineral spirits method yielded the same results in shrinkage as measured by the Hg method for a wide range of soils containing between 22 and 48% clay. Use of the silicone‐mineral spirits mixture decreases safety hazards associated with liquid Hg and is more economical.
Clay Mineral Type and Organic Compound Sorption by Hexadecyltrimethlyammonium‐Exchanged Clays
Authors: Jaynes W.F. , Boyd S.A. 
Published: July 2010

AbstractIn order to relate mineralogy to sorbent efficiency, organo‐clays were prepared from reference vermiculite, illite, smectite, and kaolinite clay minerals using the organic cation hexadecyltrimethylammonium (HDTMA). Adsorption isotherms using 14C‐HDTMA indicated stoichiometric adsorption of HDTMA up to the cation‐exchange capacity (CEC). Organo‐clays were prepared by adding HDTMA equivalent to the CEC and were evaluated as sorbents for nonionic organic compounds (NOCs) dissolved in water. X‐ray diffraction analysis of the HDTMA clays revealed basal spacings of 28 Å for the vermiculite and 23, 20, and 18 Å for the high‐charge, intermediate‐charge, and low‐charge smectites, respectively. The HDTMA vermiculite, illite, and smectites were all highly effective sorbents for NOCs, whereas Mg smectite was ineffective. The sorption isotherms of benzene, toluene, ethylbenzene, propylbenzene, butylbenzene, t‐butylbenzene, naphthalene, and biphenyl on the HDTMA clays indicated that sorption occurred by partition interactions with the HDTMA‐derived organic phase. In general, both the greater HDTMA content and the larger basal spacings of high‐charge HDTMA clays increased NOC sorption. Mineral‐charge effects on the sorption of unsubstituted aromatic compounds (benzene, naphthalene, and biphenyl) were less evident than for alkyl‐benzenes. Greater sorption of the alkylbenzenes by high‐charge HDTMA clays can be attributed to the capability of the large basal spacings to accommodate larger solute molecules. The formation of organic cation exchanged soil clays derived from vermiculite, illite, or smectite may greatly improve the ability of soils to immobilize organic contaminants.
Nitrogen Assimilation and Distribution in Field‐Grown Cowpea at Various Growth Stages
Authors: Awonaike K. O. , Kumarasinghe K. S. , Danso S. K. A. 
Published: July 2010

AbstractThe sources of N and the periods during which they are assimilated can influence the redistribution of N within different organs and, consequently, the final grain yield and N content of legumes. The 15N isotope‐dilution approach was used to measure the amounts of N derived from atmospheric N2 (Ndfa), soil (Ndfs), and fertilizer (Ndff) in the aboveground portion of field‐grown cowpea [Vigna unguiculata (L.) Walp.] at the following developmental stages: late vegetative, early pod filling, mid pod filling, and physiological maturity. The soil was classified as an Oxic Paleudalf. The principal sources of cowpea's N changed markedly during development. While Ndfs supplied 80% of the total N assimilated in the aboveground plant parts during the first 42 d of growth, Ndfa furnished over 80% of the N assimilated during the remaining and most N‐demanding period of cowpea growth. At physiological maturity, the total above‐ground plant N was composed of 100, 50, and 5 kg N ha−1 as Ndfa, Ndfs, and Ndff, respectively. The preexisting N pools in vegetative parts of cowpea did not contribute much N towards pod fill, with the currently assimilated N (predominantly as Ndfa) contributing 87% of the N for pod fill. At physiological maturity, the N in pods was only slightly in excess of Ndfa in the aboveground plant parts. We conclude that Ndfa can contribute significantly towards the N nutrition of field‐grown cowpea, serving also as an important source of N for pod development.
Soil Denitrification Dynamics: Spatial and Temporal Variations of Enzyme Activity, Populations, and Nitrogen Gas Loss
Authors: Parsons Laura L. , Smith M. Scott , Murray Robert E. 
Published: July 2010

AbstractSpatial and temporal variation in N‐gas loss (N2O evolution with C2H2), denitrifying enzyme activity (DEA), and denitrifier biomass (as determined by most‐probable‐number [MPN] counts) was measured in two agricultural soils in central Kentucky in order to characterize the extent to which denitrifying enzymes are synthesized and expressed, and how environmental conditions influence the in situ growth and activity of denitrifying bacteria. Rates of N‐gas loss from intact cores ranged from 0 to 300 µg N m−2 h−1. Nitrogen gas loss was strongly seasonal, with both soils having the most frequent activity in the spring. Nitrogen gas loss was highly variable on a spatial scale with replicate measurements exhibiting coefficients of variation between 74 and 268%. Denitrifying enzyme activity in both soils ranged from 0.1 to 119 ng N2O‐N g−1 soil min−1 and varied spatially and temporally, but did not exhibit the same seasonal pattern as N‐gas loss. Increases in DEA often followed increases in soil moisture and were commonly associated with increases in soil respiration. Denitrifier populations ranged from 3 × 103 to 1 × 106 cells g−1 dry soil but did not show the same temporal pattern as N‐gas evolution.When the entire data set was considered, none of the parameters measured, alone or in combination, adequately accounted for variation in N‐gas loss from either soil. When mean values of the parameters measured at each sampling date were considered, however, multiple‐regression models accounted for 74 to 91% of the variation in mean denitrification rate. Denitrifying enzyme activity and MPN population measurements were not good predictors of denitrification rate because N‐gas loss was not always tightly coupled to the synthesis of denitrifying enzymes or population growth.
Organic Matter Extraction from Soils with Water at High Pressure and Temperatures
Authors: Schnitzer M. , Schuppli P. , Schulten H.‐R. , Angers D. A. 
Published: July 2010

AbstractThe objective of this research was to develop a procedure for the more specific extraction of major organic matter (OM) components from soils. The method was tested on Ap horizons of a Haplaquoll, a Cryoboroll, and a Haploboroll, and on the Bh horizon of a Haplaquod. The four soils were extracted for 2 h with distilled water at a constant pressure of 17.2 MPa and at temperatures of 150, 200, and 250 °C. The OM extracts obtained were characterized by chemical methods, infrared (IR) and nuclear magnetic resonance (NMR) spectroscopy, and pyrolysis‐field ionization mass spectrometry (Py‐FIMS). With one exception, relatively more of the soil N (18–53%) than soil C (17–40%) was extracted from the four soils at the three temperatures. Recoveries of N at 200 and 250 °C were superior to those reported for extractions by 0.1 M Na4P2O7 solution from the same soils, while C recoveries were higher from the Bainsville and Regina soils. In general, extracts obtained at 200 °C were richest in carbohydrates and especially in N components. The 13C‐NMR spectra showed that most of the C in the extracts was aliphatic, occurring in the form of noncarbohydrate carbons bonded to OH and O. The Py‐FI mass spectra indicated that the extracts contained polysaccharides, n‐fatty acids, n‐alkanes, n‐alcohols, sterols, N compounds (pyrroles and pyridines), and mono‐ and dilignins, all typical OM components. Extracts obtained at 150 °C were enriched in n‐alcohols and diols, whereas extracts at 250 °C were rich in fatty acids. For the extraction of carbohydrates and N components, we recommend an extraction temperature of 200 °C; for soils rich in clay minerals, extractions at 250 °C may be more efficient. For studies on paraffinic OM components, extraction at 150 °C may be appropriate.
Flow Injection Analysis of Urea Nitrogen in Soil Extracts
Authors: Sullivan D. M. , Havlin J. L. 
Published: July 2010

AbstractFlow injection analysis (FIA) is a relatively new technique with advantages over traditional automated analysis methods in precision and sample throughput. A new procedure has been developed to measure urea in soil extracts using automated FIA. This procedure utilizes the diacetyl monoxime thiosemicarbazide colorimetric method, with a modified acid reagent that increases the rate of color formation and improves the mixing of sample with reagent in narrow‐diameter (0.8‐mm) tubing. Sixty samples can be analyzed per hour, with a detection limit of 0.01 mg urea‐N L−1. Residence time between sample injection and maximum absorbance is 130 s.
Nitrogen‐15 Recovery in Winter Wheat as Affected by Application Timing and Dicyandiamide
Authors: Bronson K. F. , Touchton J.T. , Hauck R. D. , Kelley K. R. 
Published: July 2010

AbstractNitrification inhibitor amendment to fall‐applied N for winter wheat may reduce denitrification and leaching losses of N by maintaining N in ammoniacal form. A field study on a Norfolk loamy sand (fine‐loamy, siliceous, thermic Typic Paleudult) compared fall application of 15N‐labeled urea with and without dicyandiamide (DCD) and split urea application in fall and spring. Grain yield (mean 4.26 Mg ha−1) increased with N rate (67, 101, and 134 kg N ha−1), but was not affected by DCD or time of N application. Recovery of 15N in wheat the first year (mean 53%) was not affected by DCD or time of N application. Immobilization of 15N was 21, 20, and 15% with the fall N plus DCD, split‐applied N, and fall N treatments, respectively. Nitrogen‐15 leached at harvest was less with fall N plus DCD or split‐applied N than with fall N only. Denitrification estimates, calculated as 15N not accounted for, were not affected by DCD or timing of N. In the second year, 101 kg N ha−1 of unlabeled urea was split applied across the entire experiment. Grain yields averaged 2.07 Mg ha−1 and were not affected by N rate, DCD, or timing of N application from the previous year. Percent recovery of 15N averaged 1.0 and 0.9% in the grain and straw, respectively, or about 10% of the 15N immobilized the year before. Recovery of 15N in the second year was significantly higher in the straw and roots following split‐applied N or fall N plus DCD, compared with following fall N alone. This suggests that nitrification inhibitors can affect N uptake of a second‐year crop by enhancing biological immobilization of fertilizer N.
Cropping Systems Effects on Mycorrhizal Colonization, Early Growth, and Phosphorus Uptake of Corn
Authors: Vivekanandan M. , Fixen P.E. 
Published: July 2010

AbstractA field study was established in 1986 on a Viborg silty clay loam (fine‐silty, mixed, mesic Pachic Haplustoll) soil in eastern South Dakota. The objectives were to quantify the influence of crop rotation, tillage, and residual P (254 kg P ha−1 applied in fall 1985) on the incidence of vesicular‐arbuscular mycorrhizae (VAM) of corn (Zea mays L.) and to define the relationship between VAM colonization, early growth response to P, and early P uptake of corn. Plant and root samples were collected periodically from plots that varied in tillage and previous crop. Crop rotation and tillage influenced the early growth and P uptake of corn. Large differences in early growth response to P were observed among cropping systems. Average relative growth response as compared with the check during both years ranged from 360% for the moldboard (MP) corn‐fallow rotation to 7% for the ridge‐plant (RP) corn‐soybean (Glycine max [L.] Merr.) rotation. Early dry‐matter production and P uptake in the check plots were highest in the RP corn‐soybean system and lowest in the MP corn‐fallow system. Generally, VAM colonization rates were significantly higher (P ≤ 0.10) in the RP systems than in the MP systems. Considerable reduction in VAM colonization rates were found with P fertilization (P ≤ 0.01) in all cropping systems. An inverse relationship was measured between VAM colonization and relative early growth response to P (Y = 647.0 − 49.4X + 0.97X2; R2 = 0.92; Y = growth response in percent, X = percent root length colonized). Considering early dry‐matter production, P uptake, and mycorrhizal association the RP corn‐soybean system appears to provide a good environment for P nutrition of corn during early vegetative growth.
Manganese Distributions in Acid Soils of the North Carolina Piedmont
Authors: McDaniel P. A. , Buol S. W. 
Published: July 2010

AbstractManganese is a dynamic component of soils that can be present in a variety of forms. This study was initiated to examine the distribution of Mn in Ultisols and Alfisols formed in gneisses of the North Carolina Piedmont. Secondary Mn (Mnd) and Fe (Fed) depth distributions were evaluated using a citrate‐bicarbonate‐dithionite extract; the distribution of Mn among organic and various inorganic soil fractions was determined using a sequential‐extraction procedure. Results indicate that accumulation of Mnd is related to interactions between landscape position and associated redox potential (Eh)‐pH environments rather than mineralogy of soil parent material. Spatial relationships between Mnd and Fed within soils reflect Eh‐pH‐potential gradients in these acid systems. Accumulations of secondary Mn occur in well‐drained surface horizons of soils occupying lower lying landscape positions. These accumulations occur in weathered hillslope sediments and are not related to mineralogy of the underlying residuum. As much as 50% of this Mn is associated with the organic‐matter fraction and the inorganic exchange complex. Secondary accumulations of Mn also occur in B/C horizons and saprolite residuum in soils of actively down‐wearing geomorphic positions. Most of this Mn is in the crystalline Mn oxide fraction. Data indicate a significant correlation (P < 0.01) exists between quantities of Mn found in the amorphous, exchangeable, and crystalline Mn oxide fractions.