bluuebunny/crossref_metadata_2025_split huggingface dataset:
Specificity of Arrowleaf Clover for Rhizobia and Its Establishment on Soil From Crimson Clover Pastures
Authors: Weaver R. W. , Sen D. , Coll J. J. , Dixon C. R. , Smith G. R. 
Published: July 2010

AbstractSuccessful establishment of clover (Trifolium spp.) on soil requires that the appropriate rhizobia are present to establish an N2 fixing association. Experiments were undertaken in the laboratory to determine if the rhizobial requirements of arrowleaf clover (Trifolium vesiculosum Savi) were different from those of crimson clover (Trifolium incarnatum L.) because arrowleaf clover is often being sown in pastures that have previously grown crimson clover. Generally, rhizobia capable of nodulating crimson clover were also able to nodulate arrowleaf clover but fixed little N2. Soil collected from nine pastures that were growing crimson clover and had never been planted to arrowleaf clover contained rhizobia capable of effectively (nodules fixed N2) nodulating arrowleaf clover. Protein profiles of rhizobia isolated from nodules of arrowleaf and crimson clover grown on soil from one of the nine locations indicated that at least 12 rhizobial strains were present, and those that selectively nodulated crimson clover generally were not able to fix N2 or showed delayed nodulation on arrowleaf clover. When arrowleaf clover was grown on the same soil, four of the five strains that formed nodules on its roots were effective. It appears that arrowleaf clover was able to select effective rhizobia from a mixed population and that it may be successfully established on fields that have grown crimson clover, even though the rhizobial requirements for the two hosts are different.
Effect of Bedrock Porosity on Soils Formed from Dolomitic Limestone Residuum and Eolian Deposition
Authors: Levine S. J. , Hendricks D. M. , Schreiber J. F. 
Published: July 2010

AbstractDifferences in the weathering characteristics of dolomitic limestones have resulted in the formation of Haplustalfs and Calciustolls located in the northwestern Colorado Plateau of Arizona. The establishment of effective porosity in the parent rock has controlled important pedogenic processes such as decalcification and silicate clay illuviation. The underlying carbonate strata, the Kaibab Formation, are complex limestone‐dolomite‐chert marine rocks of Permian age. Pleistocene age meteoric waters have caused the dissolution and partial removal of CaCO3 and the establishment of a porous dolomite crystal framework. Under these conditions, soils forming in residuum are able to decalcify and to form argillic horizons. However, in more resistant limestones, compaction during burial has resulted in a nonporous micrite that retards calcite removal by meteoric waters. Under these conditions, soil profiles maintain a high CaCO3 content and silicate clay illuviation does not occur. Eolian dust is also important to soil formation on the Colorado Plateau; in particular, quartz in the coarse silt fraction (31–44 µm), and quartz and biotite in the very fine and fine silt fractions (2.0–11 µm). Micaceous clay minerals of residual and eolian origin are converted to montmorillonite in the Alfisols. A probable sequence of events for this transformation to occur is: (i) the removal of calcite from the dolomitic limestone bedrock and the formation of a dolomite crystal framework, (ii) the slow dissolution of dolomite and release of Mg2+ into solution, (iii) the incorporation of Mg2+ into the octahedral layer of the mica and the release of K+ from the mica interlayer position, and (iv) the illuviation of montmorillonite to form the argillic horizon.
Nutrient Flux Through a Loblolly Pine Forest Floor Using Simulated Rainfall
Authors: Duffy P. D. , Schreiber J. D. , McDowell L. L. 
Published: July 2010

AbstractSimulated rainfall was applied to 1‐m2 forest floor plots in a 45‐yr‐old loblolly pine (Pinus taeda L.) plantation using a multiple‐intensity simulator. On Day 1, 127.0 mm was applied and on Day 2, 76.2 mm. Runoff, collected at intervals throughout the applications, was analyzed for total organic C (TOC), PO4‐P, NH4‐N, and NO3‐N. Deionized water (mean pH 5.3) and simulated acid rain (mean pH 4.2) were applied to two separate, replicate plots. The simulated acid rain reduced NH4‐N concentrations in runoff from 0.08 to 0.04 mg L−1 but did not affect TOC or PO4‐P. The TOC and PO4‐P concentrations in runoff from all simulated rainfall applications were 18 and 0.011 mg L−1, respectively. The NO3‐N concentration was 0.02 mg L−1 for nonacid applications; the effects of acid applications on NO3‐N were not determined because of analytical problems. Nutrient flux during nonacid rainfall applications for TOC, PO4‐P, NH4‐N, and NO3‐N were, respectively, 5.2, 0.003, 0.021, and 0.006 mg m−2 mm−1 of applied rainfall. The pH was higher in runoff than in the applied acid rainfall but lower than in the applied nonacid rainfall.
Aluminum Precipitation and Dissolution Rates in Spodosol Bs Horizons in the Northeastern USA
Authors: Dahlgren R. A. , Driscoll C. T. , McAvoy D. C. 
Published: July 2010

AbstractThe kinetics of Al precipitation/dissolution reactions in Spodosol Bs horizons from sites at Hubbard Brook, NH and Bear Brook, ME were examined. A mechanical vacuum extractor was employed to draw solutions through soil columns at solution/soil residence times between 0.3 and 100 h. Equilibrium was approached from conditions of both undersaturation and oversaturation to determine if a particular soil mineral controlled Al3+ activity. Column leachates were analyzed for major solutes followed by chemical speciation and calculation of mineral saturation indices. Our results showed that apparent equilibrium with respect to Al(OH)3 solubility was readily obtained from both conditions of undersaturation and oversaturation within 0.3 h. Computed saturation indices, for an Al(OH)3 mineral with log K25C = 8.1, were identical at all examined residence times. Aquo Al (Al3+) within soil solutions may be regulated by the hydroxy‐Al interlayer of expansible 2:1 layer silicates. Soil solutions from Bear Brook also reached apparent equilibrium with imogolite at residence times in excess of 10 h. The laboratory results compared favorably with saturation indices calculated from stream and soil solutions at these sites.
Development Rates of Late Quaternary Soils, Silver Lake Playa, California
Authors: Reheis Marith C. , Harden Jennifer W. , McFadden Leslie D. , Shroba Ralph R. 
Published: July 2010

AbstractSoils formed on alluvial fan deposits that range in age from about 35 000 to 200 yr BP near Silver Lake playa in the Mojave Desert permit study of the rates of soil development in an arid, hyperthermic climate. Field‐described properties of soils were quantified and analyzed using a soil development index that combines properties and horizon thicknesses. We compared the variability in index values from five independent descriptions of the same soil profile with the variability in values from four soils of the same age described by different people. The variability due to description accounts for between 30 and 80% of the total variability (that due to both the soils and description) for the properties described, which emphasizes the need for consistent soil descriptions. Pedogenic CaCO3 (as indicated by color), pH increase, and dry consistence appear to change with age at linear rates, whereas rubification appears to change at a logarithmic rate. The linear rates are best attributed to the progressive accumulation of CaCO3‐ and salt‐rich eolian dust derived from the playa and other more distant sources. The total‐texture values of soils on fans older than 10 000 yr BP are similar, which suggests that playas in this area may have been wet enough to restrict the availability of fines from these sources for many thousands of years prior to 10 000 yr BP. Index values for most properties of soils on the lower fans adjacent to the playa increase at faster rates than those of soils of the same age on the upper fans farther from the playa, probably due to the proximity to this local dust source. Equations derived from regressions of soil age and properties can be used to estimate ages of undated, lithologically similar deposits in similar climates and geomorphic settings.
Classifying Soils for Acidic Deposition Aquatic Effects: A Scheme for the Northeast USA
Authors: Lee J. J. , Lammers D. A. , Stevens D. L. , Thornton K. W. , Wheeler K. A. 
Published: July 2010

AbstractThe Direct/Delayed Response Project (DDRP) is estimating the number of lakes and streams in three U.S. regions that might become acidic due to current or altered levels of acidic deposition, and the long‐term time scales involved. Because of the influence of soils on aquatic chemistry, DDRP acquired data on soils that were mapped, sampled, and analyzed consistent methods across the regions. In the northeastern USA, about 600 soils (mainly phases of soil series) were identified during mapping of 145 watersheds. Because statistically adequate sampling of every soil was impractical, the soils were grouped into 38 sampling classes. Each of these classes was sampled across several (usually eight) watersheds. The properties of soils on specific watersheds (or portions of watersheds) can be estimated from the regional means and variances of the sampling classes and the percent occurrence of sampling classes on each watershed. This paper describes how the sampling classes for the northeastern USA were developed, the definitions of the classes, and the characteristics of soils within the classes. A preliminary statistical test indicates that the occurrence of sampling classes on watersheds is a significant predictor of Acid Neutralizing Capacity class of the corresponding lakes. Final evaluation of the utility of this scheme will come from the very extensive data analysis and modeling tasks of the DDRP.
Fertilizer Phosphorus Recommendations for Winter Wheat in Terms of Method of Phosphorus Application, Soil pH, and Yield Goal
Authors: Fiedler R. J. , Sander D. H. , Peterson G. A. 
Published: July 2010

AbstractThe objective of this study was to predict the most profitable amount of P fertilizer applied to winter wheat in terms of grain yield increase as influenced by soil test P, method of P application, and projected yield level. Winter wheat (Triticum aestivum) was grown in 22 field experiments between 1978 and 1982 with treatments consisting of six P rates applied with the seed and broadcast. The soils were Keith‐Holdrege and Uly‐Colby silt loam (fine‐silty, mixed mesic Typic Argiustolls). Yield increase to applied P was related by multiple regression to rate and method of P application, soil P level, soil pH, and grain yield level (R2 = 0.76, SE = 0.20 Mg ha−1). This function estimates maximum profit at specific fertilizer and grain prices. The regression function provides a mathematical solution for incorporating yield goal into fertilizer P recommendations. The model shows that P requirements for winter wheat increase as the yield level increases. Most importantly, the model indicates that it is economically prohibitive to follow the traditional recommendations of doubling the rate of broadcast P compared to seed applied P for winter wheat. When grain yields are increased with applied P, seed applied P results in much higher grain yield increase per kilogram of applied P than broadcast P. This results in being able to pay for more P when seed applied than broadcast. At medium and low levels of soil P, seed application resulted in 2 to 4 times more profit from fertilizer P application than broadcast P.
Analysis of Water Flow under Trickle Irrigation: II. Experimental Evaluation
Authors: Lafolie F. , Guennelon R. , van Genuchten M. Th. 
Published: July 2010

AbstractA numerical solution for predicting soil water content distributions during trickle irrigation on stratified and anisotropic soils was compared with data from a field experiment carried out on a loamy clay soil using 24 field plots irrigated at different rates and frequencies. The unsaturated hydraulic conductivity was estimated from measured soil water retention and saturated hydraulic conductivities. Observed volumetric soil water contents and saturated areas on the soil surface were compared with model predictions. The effects of anisotropy and soil surface crusting on experimental and calculated soil water distributions were also investigated. Relatively good agreement was obtained between predicted and measured soil water content distributions vs. depth. The shape of the observed wetted soil volume was also predicted reasonably well. The effects of possible errors in the hydraulic characteristics on calculated water content distributions are discussed.
Method for the Sequential Extraction of Organic Matter from Soils and Soil Fractions
Authors: Schnitzer M. , Schuppli P. 
Published: July 2010

AbstractThe extraction of organic matter (OM) from soils is one of the unresolved problems in soil chemistry and biochemistry. To contribute to the solution of this problem, we developed a procedure for the extraction of OM in which the following sequence of extractants is used: (i) n‐hexane; (ii) chloroform; (iii) 0.1 M Na4P2O7 solution under N2; (iv) 0.5 M NaOH solution under N2; and (v) distilled H2O. The n‐hexane extracts alkanes and fatty acids; chloroform removes fatty acids, long‐chain alcohols, and wax esters; 0.1 M Na4P2O7 solution extracts OM “complexed” to metals and clays; whereas 0.5 M NaOH and H2O remove “free” OM, that includes less decomposed materials. The method was tested on three soils and 25 particle‐size fractions separated from these soils, which varied in mineralogical composition and OM content. Our data show that 0.1 M Na4P2O7 solution extracts relatively more OM from finer soil particles than from coarser ones while the reverse is true for 0.5 M NaOH solution. In general, OM is more readily extracted from soils low in clays than from those rich in clays. Between 35.4 and 80.9% of the soil‐C and between 21.0 and 75.6% of the soil‐N are solubilized. Determinations can be made at each step of the procedure of how much of the initial OM and which major components are extracted. Humic acids isolated from the 0.1 M Na4P2O7, 0.5 M NaOH and H2O extracts have analytical characteristics which are very similar to those of typical soil humic acids.
Cone Index Values Diagnostic of Where Subsoiling Can Increase Corn Root Growth
Authors: Vepraskas M.J. , Wagger M.G. 
Published: July 2010

AbstractTo identify root restrictive layers in a field using a penetrometer, a diagnostic cone index (CI) value indicative of restricted root growth must be known for the particular soil and crop. This investigation identified diagnostic CI values indicative of where corn (Zea mays L.) root abundance could be increased by subsoiling. Two tillage treatments were evaluated in seven Typic and Arenic Paleudults from 1985 through 1987. Penetrometer readings were made weekly in the plant row of both tillage treatments to a depth of 0.4 m. Roots were described primarily between 77 and 90 d after planting (DAP). Root observations were expressed on a proportional basis and were termed relative root abundance. Regression analyses showed that relative root abundance in the chiseled treatment was related to mean CI, depth, and clay percentage (R2 = 0.85). By 77 to 90 DAP, subsoiling significantly (P> 0.10) reduced mean CI as compared to the chiseled treatment at depths below 0.1 m, while significant increases in relative root abundance as a result of subsoiling were found primarily at 0.3 to 0.4 m. Diagnostic CI values for the chiseled treatment were identified where relative root abundance could be increased by subsoiling. Diagnostic CI values decreased with soil depth and increased with clay percentage. For a depth of 0.35 m, subsoiling was estimated to increase root abundance where the mean CI over a 3‐ to 5‐wk period was greater than approximately 1.5, 3.0, and 4.5 MPa for soil layers having clay percentages of 4, 12, and 20%, respectively.
Calibration of Nitrogen and Phosphorus Soil Tests with Yield of Proso Millet
Authors: Rodriguez J. B. , Peterson G. A. , Westfall D. G. 
Published: July 2010

AbstractCurrent fertilizer recommendations for proso millet (Panicum miliaceum L.) are based on soil test calibrations developed for related crops such as corn (Zea mays L.) and sorghum [Sorghum bicolor (L.) Moench]. Therefore, their accuracy may be questionable. A study was initiated to correlate and calibrate the AB‐DTPA, Olsen P, Bray P‐1, and Mehlich P‐1 soil tests for P and the soil profile NO3‐N test with proso millet yields. Most of the soils studied were Argiustolls. Fourteen dryland field experiments were conducted from 1985 through 1987 in eastern Colorado. The experiments were N and P factorials with N levels of 0, 22, 45 and 67 kg ha−1 and P levels of 0, 8, and 17 kg ha−1. Profile soil samples were taken and analyzed for P by each of the soil P tests and for extractable NO3‐N. Grain yield was measured at maturity. Critical levels were established for each soil P and N test. Critical levels (point below which response to fertilizer is expected) were 6, 12, 20, and 35 mg kg−1 of P (0‐15‐cm sample depth) for the AB‐DTPA, Olsen P, Bray P‐1, and Mehlich P‐1 tests respectively. For N the critical level was 58 kg ha−1 in the 0‐ to 90‐cm soil profile. Soil test categories for each P test were established. The amount of P needed to correct deficiency and obtain maximum yield was 16, 12, 7 and 0 kg ha−1 for VL, L, M, and H categories, respectively. The amounts of N were 45, 25, 15 and 0 kg ha−1 for the respective categories.
Analytical Extensions of the Discrete Interface Penetration Model for Dynamic Permeability Analysis
Authors: Jennings Aaron A. , Ravi Varadhan 
Published: July 2010

AbstractDiscrete interface penetration modeling has recently been proposed to quantify the phenomenological domain response to permeants that substantially alter soil's hydraulic conductivity. Analytical solutions are presented here for a dual‐interface model compatible with constant‐head, constant‐flux, or falling‐head permeameter testing. It is demonstrated that the nondimensional transient saturated hydraulic conductivity response K̄(t) is independent of permeameter design. Solutions are also presented for the transient potential field φ̄(X,t) and interface locations X̄1(t), X̄2(t) that would accompany the infiltration episode.
Cadmium Buffering Capacity and Accumulation in Swiss Chard in Some Sludge‐Amended Soils
Authors: Kuo S. 
Published: July 2010

AbstractCadmium sorption by soils could be an important factor regulating the plant availability of soil Cd. Five soils containing varying amounts of Cd resulting from previous sludge application were analyzed for residual Cd availability under field conditions using Swiss chard (Beta vulgaris L.) as an indicator plant. The Cd accumulation was not highly correlated with DTPA (diethylene‐triamine‐pentaacetic acid)‐extractable Cd (R2 = 0.53). This result may be explained by a dissimilar response of plant Cd and DTPA Cd to soil pH. However, DTPA extracted 50 to 75% of sorbed Cd, depending on soil type. The recovery was little affected by the quantity of Cd sorbed. As such, DTPA Cd could be used to predict Cd accumulation by converting it to the quantity of Cd sorbed (Cds). The Cds was combined with the pH‐dependent Cd buffering capacity (BC) to obtain Cds/BC, an intensity factor for soil Cd. The buffering capacity is defined as the slope of the Cd‐sorption isotherm. The Cds/BC and plant Cd were highly correlated over all the soils, using the Michaelis‐Menten equation as a model (R2 = 0.83).
Factors Influencing Soil Structural Stability within a Growing Season
Authors: Perfect E. , Kay B. D. , van Loon W. K. P. , Sheard R. W. , Pojasok T. 
Published: July 2010

AbstractTemporal fluctuations in soil structural stability within cropping treatments are often as large as differences between crops during the growing season. The relative importance of soil moisture, roots, and microbial biomass as factors contributing to this variation were investigated. Research was conducted on a fine‐silty, mixed, mesic Typic Eutrochrept intergrading to a fine‐silty, mixed, mesic Typic Haplaquept soil near Elora, ON. Six perennial forage treatments, established 2 yr previously, were compared with spring‐seeded conventional and zero‐till corn (Zea mays L.). The plow layer of each cropping treatment was sampled at monthly intervals. A combination of wet sieving and turbidimetry was used to provide a rapid assessment of wet aggregate stability (WAS) and dispersible clay (DC), respectively. On average, the forages had significantly less DC and greater WAS than the two corn treatments. Structural stability was found to decrease with increasing soil water content (r = 0.80 for DC and r = 0.74 for Was, both significant at P = 0.01). The corn soil experienced less extreme drying in the spring. Stepwise multiple‐regression analyses selected soil moisture and microbial biomass (in that order) as significant predictors of structural stability within the growing season. Using both parameters, it was possible to explain up to 85% of the temporal variation in DC and WAS on a by‐treatment basis.
Tillage Effects on the Spatial and Temporal Variations of Soil Water
Authors: Zhai R. , Kachanoski R. G. , Voroney R. P. 
Published: July 2010

AbstractThe objective of this study was to examine the effect of tillage on the spatial and temporal variability of soil water content of the surface layer (0–0.2 m) under a corn (Zea mays L.) crop. Soil water content was measured nondestructively every 1 to 2 d in fall moldboard (CT), 1‐yr no‐tillage (SNT), and longer term (>15 yr) notillage (LNT) plots using permanently placed time domain reflectometry (TDR) transmission line probes. The plots are located near Guelph, ON, Canada on a Typic Hapludalf (loam) soil. Sampling sites were in the corn row, directly between corn rows (interrow), and halfway between the row and interrow (quarter row). Systematic spatial differences in soil water content, within and between tillage treatments, were observed throughout the entire growing season. Large differences between CT and both LNT and SNT early in the season were attributed to increased evaporation in CT caused by spring secondary tillage. The drying rate in the LNT interrow position was much lower than the CT and SNT interrow drying rates. Soil water recharge from rainfall was distributed systematically in space because of canopy interception and subsequent stemflow. Crop residue on the soil surface of the no‐till treatments intercepted a significant amount of rainfall and reduced soil water recharge by 14 and 35% in the SNT and LNT treatments, respectively. The tillage treatments affected the temporal dependence of the spatial variability of soil water and the spatial dependence of the temporal variability.