bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quality Parameters of Spring Wheat and Forage Crops Related to Topsoil and Subsoil Thickness
Authors: Power J. F. , Ries R. E. , Sandoval F. M. 
Published: July 2010

AbstractNumerous factors affect the composition and quality of crops. One of these factors is soil thickness, which can affect quantity of nutrients available, availability of water, and rooting depth. This experiment was conducted in North Dakota to determine the effects of variable thicknesses of topsoil and subsoil over sodic mine spoils on nitrogen (N) and phosphorus (P) concentrations in blue grama and side oats grama (Bouteloua gracilis and Bouteloua curtipendula), crested wheatgrass (Agropyron desertorum), alfalfa (Medicago sativa), and hard red spring wheat (Triticum aestivum). Milling and baking qualities of spring wheat were also evaluated. Total phosphorus concentration in most crops was not consistently affected by subsoil thickness; however, total P in plant material was usually greatest when subsoil was covered with either 20 or 60 cm of topsoil. Mixing subsoil and topsoil in a 3:1 ratio frequently gave plant P concentrations almost as low as for treatments of no topsoil over subsoil. A notable exception was alfalfa.Plant nitrogen concentration tended to decrease as subsoil thickness increased. Much of this decrease may have resulted from simple dilution, since total plant growth generally increased as total soil thickness increased to 90 to 120 cm. Except for alfalfa, N concentration was greater in all crops produced on 20 to 60 cm of topsoil over subsoil than on plots with no topsoil or subsoil and topsoil mixed.Generally, milling and baking properties of the wheat grain were closely related to the grain N concentration. Based on several parameters of milling and baking quality, flour from wheat produced on plots with 20 or 60 cm of topsoil generally was superior in milling and baking properties to flour from wheat on plots with no topsoil or with subsoil and topsoil mixed.In general, presence of topsoil affected crop quality by enhancing nutrient uptake by the plant. On the other hand, increased subsoil thickness often increased rooting depth and water availability, resulting in increased plant growth and, consequently, dilution of nutrient concentrations in the crops produced.
Subsidence and Erosion of a Histosol
Authors: Parent L. E. , Millette J. A. , Mehuys G. R. 
Published: July 2010

AbstractThe usual model of Histosol subsidence emphasizes the influence of the water table level on peat shrinkage and biochemical oxidation. It predicts a decrease in subsidence rate with time. However, erosion may increase the rate of subsidence significantly. The long‐term subsidence rate of the Histosol under study, where vegetable crops were grown yearly, was estimated at 2.06 ± 0.35 cm/year between 1936 and 1974. In 1974, part of the fields was sown in oats, as a conservation measure, whereas a windbreak was removed in 1976 and unusual meteorological events were recorded in 1974 and 1975. Erosion patterns were detected on the portion of the experimental site where there was no conservation measure. Between 1974 and 1978, the subsidence rate was reduced to 0.99 ± 1.59 cm/year in fields protected against erosion but increased to 4.53 ± 2.29 cm/year in unprotected fields. The decrease in subsidence rate predicted by the model was observed only in fields protected by conservation measures. Consequently, subsidence and erosion should be estimated separately for modelling adequately the subsidence process as a whole.
Portable Hand‐Operated Soil Core Sampler
Authors: Chong S. K. , Khan M. A. , Green R. E. 
Published: July 2010

AbstractA simple sampling apparatus was developed to take soil cores for characterizing soil‐water relations. A portable steel frame, which is anchored to the soil surface by the operator's weight and by stakes driven into the soil, provides support for a hand‐operated 2‐ton hydraulic jack which pushes the core cylinder into the soil without impact or vibration. The method is labor‐intensive but provides highquality soil cores.
Water Adsorption and Swelling of Clay Minerals in Soil Systems
Authors: Parker J. C. , Amos D. F. , Zelazny L. W. 
Published: July 2010

AbstractVolume changes of undisturbed (U) samples of Poplimento and Iredell B2 horizons, and of samples compacted at optimum (CO), below optimum (CL), and above optimum (CH) moisture were measured during wetting, drying, and re‐wetting. Poplimento contained 9% montmorillonite and 11% vermiculite while Iredell had 48% montmorillonite and 15% vermiculite on a whole‐soil basis. During the initial wetting of Poplimento samples, variations in volume change between treatments were small. This suggests that changes in soil structure with increasing moisture during compaction counteracted normal moisture‐dependent differences by reducing space for expansion into larger voids or by increasing expansion from entrapped air pressures, strain relaxation, and differential strain. Compacted Iredell samples displayed an inverse relationship between moisture at compaction and swelling during the first wetting. Undisturbed Iredell samples exhibited considerably less expansion than compacted samples.Expansion during the second wetting followed the order U ≃ CO ≃ CH > CL for Poplimento and CO > U ≃ CH > CL for Iredell. Swelling attributable to entrapped air pressures accounted for 59, 50, 39, and 8% of the total expansion for U, CL, CO, and CH Poplimento samples and for 23, 13, 27, and 22% of similarly treated Iredell samples. These values do not appear to reflect the inverse relationship between entrapped air pressures and probable pore size which is suggested by the Laplace equation. Rate of water uptake and resistance to expansion may explain this discrepancy. Estimated osmotic adsorption accounted for 30, 61, 32, and 31% of the volume change of U, CL, CO, and CH Poplimento samples and 46, 51, 43, and 46%, respectively, for Iredell samples. Intracrystalline swelling accounted for only 3 to 6% of the total expansion in Poplimento and 8 to 9% in Iredell.The discrepancy between these three components of swelling and measured expansion was taken as an indicator of the magnitude of swelling caused by crystal strain relaxation and differential strains between adjacent crystals or aggregates. These components appeared to increase with increasing compaction moisture for Poplimento, while in Iredell they were unaffected by treatment. For the CL Poplimento sample the sum of these components exceeded the measured swelling suggesting accommodation of osmotic swelling within relatively large pores.
Absorption of Water by Soil: The Effect of a Surface Crust
Authors: Smiles D. E. , Knight J. H. , Perroux K. M. 
Published: July 2010

AbstractThe one‐dimensional absorption of water by a uniform soil through a relatively impermeable surface layer is analyzed using conventional soil physics theory. The analysis permits calculation of the evolution of the water potential on the interface between the soil and the crust, the water content profiles, and the cumulative volume of water absorbed.In the first instance the approach is tested for situations where the conductance of the crust is constant.Extensions of the analysis to cases where the conductance is time‐dependent are foreshadowed.
Soil Pore Structural Stability and Irrigation Water Quality: I. Empirical Sodium Stability Model
Authors: Cass A. , Sumner M. E. 
Published: July 2010

AbstractThe use of a unique threshold concentration curve as an indication of soil pore structural stability is questionable. Not only is the choice of a particular value of relative hydraulic conductivity arbitrary but, in addition, the threshold concentration curve does not reveal soil resistance to hydraulic conductivity reductions over a range of solution composition or concentration changes. In order to overcome this deficiency an empirical sodium stability model is proposed which expresses the relationship between the slopes of the threshold concentration curves as a function of the degree of hydraulic conductivity reduction. This model provides a means of evaluating both the susceptibility to hydraulic conductivity reductions and the degree of hydraulic conductivity change as the percolate concentration is altered.
An Improved Technique for Determining Soil Electrical Conductivity‐Depth Relations from Above‐ground Electromagnetic Measurements
Authors: Corwin D. L. , Rhoades J. D. 
Published: July 2010

AbstractAn improved method has been developed for determining the distribution of bulk soil electrical conductivity, ECa, through the soil from electromagnetic measurements taken at the soil surface with the Geonics Limited EM‐38 device. Induced electromagnetic conductivity readings taken with the EM‐38 device's coil configuration oriented parallel and then perpendicular to the soil surface provided sufficient information, when used with equations derived from geophysical instrumentation data, to produce a soil electrical conductivity‐depth profile. The simplicity of this method further enhances the praiticability of the newly developed electromagnetic technique for field measurements of salinity and for saline seep diagnosis.
Bacterial Water Relations Using Polyethylene Glycol 4000
Authors: McAneney K. J. , Harris R. F. , Gardner W. R. 
Published: July 2010

AbstractThe effect of polyethylene glycol (PEG) 4000 on the growth of Arthrobacter crystallopoietes and Escherichia coli was evaluated in succinate‐limited batch culture. Arthrobacter crystallopoietes was little affected by PEG down to −1.5 MPa, and showed optima in both growth rate and cell nitrogen yield around −1.0 MPa, consistent with loss of turgor as the passive mechanistic response of this organism to matric water potential stress. The apparent growth rate (difference between the growth and death rates) of E. coli decreased 70% from 0 to −0.75 MPa, with extinction at −0.8 MPa compared to extinction at −4.0 MPa under salt stress. A relatively constant level of dissimilatory CO2 production independent of PEG (inconsistent with a substantially increased energy requirement for growth under PEG stress), together with microscopic and nitrogen balance evidence of increasing cell death and lysis under increasing PEG stress, indicated that accelerated cell death was a major factor contributing to the reduction in growth rate of E. coli caused by decreasing PEG matric water potential. Volume changes in the cell wall under PEG stress are postulated as interfering with turgor pressure modulation and maintenance of cell integrity by E. coli.To the extent that PEG is acting purely as an impermeant osmoticum, then over the 0‐ to −1.5‐MPa range, any effect of soil matric water potential on the growth of A. crystallopoietes may be attributed to a solute‐diffusion problem. However, reductions in the soil matric water potential in the < −0.25‐MPa range are predicted to severely repress the growth of E. coli, with growth extinction at about −0.8 MPa, independent of water content‐solute transport considerations.
Mineralization of Nitrogen in Organic Soils
Authors: Reddy K. R. 
Published: July 2010

AbstractThe effect of fluctuating seasonal temperatures on the release of soluble NO‐3‐N, NH+4‐N, soluble organic N (SON), and solube organic C (SOC) into drainage effluent during soil organic matter mineralization was measured on organic soil profiles obtained intact from various locations in Florida. Soil columns were leached once every 25 days, followed by applying a suction of 100 cm. Soil columns were flooded for 25 days each in the months of July and August to simulate normal agronomic practices. Leachate was analyzed for NO‐3, NH+4, SON, and SOC.The amounts of N mineralized ranged from 410 to 938 kg N·ha−1·year−1 for cultivated soils and 874 to 1,250 kg·ha−1·year−1 for virgin soils. Nitrate accounted for 48 to 81% of the total N in the effluent, while SON accounted for about 16 to 45% of the total N. Remaining 2 to 7% of the total N in the effluent was NH+4. Soluble organic C in the leachate accounted for about 1,795 to 3,516 kg C·ha−1·year−1. Seasonal fluctuations in temperatures had minimal effects on the release of SON, SOC, and NH+4, but the release of NO‐3 was increased with an increase in average daily temperature (9.4 to 30°C) with Q10 values ranging from 1.3 to 1.9. Flooding the organic soils increased the SON and SOC release into the effluents by about two‐fold, compared to drained conditions. Total N loss in 1 year as a result of organic matter mineralization was about 1.3 to 4.2% of the total soil organic N.
Distribution Patterns of Ammonium Nitrogen and 15N Uptake by Rice after Deep Placement of Urea Supergranules in Wetland Soil
Authors: Savant N. K. , De Datta S. D. , Craswell E. T. 
Published: July 2010

AbstractIn‐situ distribution patterns of ammonium nitrogen (NH+4‐N) and 15N uptake by wetland rice (Oryza sativa L.) were studied on the farm of the International Rice Research Institute (IRRI) during the 1979 dry season. Individual 2‐g urea supergranules were placed at 5‐, 10‐, and 15‐cm soil depths in wetland rice plots transplanted at spacings of 20 by 20 cm and 10 by 40 cm. The ammonium (NH+4) concentration gradients near placement sites showed that the NH+4 movement was slow; in the transplanted plots, NH+4 concentrations decreased with time largely due to plant uptake. Distribution patterns of NH+4 were influenced by the depth of supergranule placement and the transplanting geometry. In general, the greater the distance from the point of placement of supergranule to the plant, the slower was the depletion of NH+4‐N at the placement site. During the dry season, the NH+4 almost completely disappeared during the 40 days after transplanting, whereas during the wet season, NH+4 persisted for up to 40 days after transplanting.The 15N uptake patterns were s‐shaped. During the first 20‐day period after transplanting, deep‐placed N was presumably physically or spatially unavailable, and negligible plant uptake occurred. After 20 days, the 15N uptake was retarded by placement of supergranules at lower depths and away from the rice hills. However, at final harvest more 15N was taken up from urea placed at the 15‐cm depth than from the 5‐cm depth. A marked lower recovery of split‐applied urea‐N (25 to 34%) than that of deep‐placed urea‐N (50 to 61%) was observed.
Spodosols Along the Southwest Oregon Coast
Authors: Nettleton W. D. , Parsons R. B. , Ness A. O. , Gelderman F. W. 
Published: July 2010

AbstractTwenty‐five Spodosols and Inceptisols under forest were examined. Their climate is moist, marine, and temperate. Winters are cool and wet and summers mostly dry. The soils have some brittle horizons but should not be in duric subgroups. Pellets sand‐size or coarser and thin ortstein horizons are accessory spodic horizon features that may reliably be used for field recognition of spodic horizons. About 90% of these Spodosols can be recognized by morphology alone. The accessory spodic horizon features, however, recognize about 20% more pedons than will pass the chemical tests. Use of the accessory spodic horizon features and the relationship found between geomorphic surfaces and soils increases the quality and rate of mapping. Typic Udipsamments are in late Holocene dunes. Yaquina, an Aquic Haplorthod, is in the winter‐wet, interdune sites on the early Holocene Tenmile surface. Netarts, an Entic Haplorthod, is on summits and side slopes of the stabilized dunes of the next higher surface, Whiskey Run, which formed during the early Holocene and late Pleistocene. Blacklock, on the Pleistocene Pioneer surface, and Joeney, on the Seven Devils surface, are both Typic Sideraquods in ortstein families like most of the soils on these surfaces. The Blacklock and Joeney pedons we sampled are taxadjuncts to their respective series because they have iron/clay ratios of < 0.2.
Distribution of Available Nitrogen in Undisturbed Forest Soil Cores Following Fertilization with Urea and Ammonium Nitrate
Authors: Pang Patrick C. K. 
Published: July 2010

AbstractUndisturbed soil cores collected from a 31‐year‐old Douglas‐fir (Pseudotsuga menziesii Mirb. Franco) plantation near Shawnigan Lake, B.C., were fertilized with (NH2)2CO (200 and 400 kg N ha−1) and NH4NO3 (200 kg N ha−1) and incubated for up to 5 months at 20°C/12°C (14‐hour day/10‐hour night) with air humidity of 80 to 85%. Cores with the 200 kg N ha−1 rate of fertilization were also given three monthly 24‐hour simulating precipitation treatments followed by incubation, starting 1 month after fertilization. Under conditions with or without precipitation, (NH2)2CO and/or NO‐2 were never detected in soil (forest floor plus mineral horizons) or leachates, and movement of ammonium (NH+4) beyond the forest floor was limited. In the absence of precipitation, a small amount of NO‐3 (9 to 18 µg N g−1 of dry soil) was detected in soil with (NH2)2CO fertilization, whereas up to 124 µg N g−1 of dry soil was detected with NH4NO3 fertilization. Redistribution of nitrate (NO‐3) was limited and approximately 90% of it remained in the forest floor. With precipitation, a NO‐3 concentration of 1 µg N g−1 was detected in soil over the study period after (NH2)2CO fertilization. With NH4NO3 fertilization, a maximum quantity of 32 µg N g−1 of NO‐3 was detected in the forest floor after the first precipitation treatment and only a trace (2 µg N g−1) was detected after the third precipitation treatment. Leaching of NO‐3, though small (10 mg N liter−1), was restricted to NH4NO3 fertilization. The recovery of nitrogenous fertilizers, (NH2)2CO or NH4NO3, as NH+4 plus NO‐3 never exceeded 53% of the amount applied. The incomplete recovery of the fertilizers as inorganic‐N could be due to biological immobilization of N, or interactions of organic matter with unhydrolyzed (NH2)2CO, NH+4 (from urea hydrolysis and NH4NO3 ionization), or NO‐2 (from NH+4 oxidation and NO‐3 reduction).
Long‐term Response to Phosphorus Fertilization on Selected Southeastern Coastal Plain Soils
Authors: Pritchett W. L. , Comerford N. B. 
Published: July 2010

AbstractSignificant response in height, diameter, basal area, and volume growth to phosphorus (P) fertilization at time of planting lasted 17 to 20 years on a variety of sites in northern and western Florida. Ground rock phosphate and the more soluble ordinary superphosphate were equally effective P sources. Comparing the residual fertilizer P in the soil to a long‐term response of slash pine (Pinus elliottii Engelm. var elliottii) helped explain lack of differences in effectiveness of P sources. The largest long‐term slash pine responses were apparent on a poorly drained Ultisol and Inceptisol while the Spodosols were more variable in their response. There were no P responses on well‐to‐excessively‐drained Entisols.
Silica Associated with Fragipan and Non‐Fragipan Horizons
Authors: Steinhardt G. C. , Franzmeier D. P. , Norton L. D. 
Published: July 2010

AbstractAll horizons of two fragipan soils and one nonfragipan soil were extracted with a sodium citrate‐bicarbonate‐dithionite (CBD) reagent and 0.5N NaOH. Both produced a maximum in extractable silicon (Si) in the fragipan horizon, but NaOH extracted about 10 to 40 times as much Si as did CBD. This Si appears to be a critical part of the fragipan, because in the nonfragipan soil, extractable Si shows no subsurface maximum at the depths in which fragipans occur.
A Simple System for Repeated Soil Resistance Measurements at the Same Spot
Authors: Nadler Arie , Magaritz Mordekcai , Lapid Yigael , Levy Y. 
Published: July 2010

AbstractAn AC (alternating current) generator and a multi‐electrode probe (MEP) were used for field measurement of bulk‐soil electrical conductivity (ECa). The MEP enabled unlimited, repeated, fast measurements of ECa at a certain spot. The MEP was operated by a portable, inexpensive, sine‐wave AC generator for obtaining ECa values based on the four‐electrode method.
Estimating the Soil Water Dependence of the Electrical Conductivity Soil Solution/Electrical Conductivity Bulk Soil Ratio
Authors: Nadler Arie 
Published: July 2010

AbstractA procedure is developed to calculate the ratio between electrical conductivity (EC) solution (ECw) and EC of bulk soil (ECa) as a function of soil water content (θ). This ratio, (F), changing nonlinearly with θ, is used to calculate soil solution salinity from measurements of bulk soil electrical conductivity. Obtaining F‐θ relationships for intermediate and low soil moisture levels by an accurate theoretical model is impractical due to the complicated interdependence of several solid‐ and liquid‐phase parameters. Therefore an empirical approach was adopted to obtain the complete F‐θ relationship by superimposing the complete suction‐water retention relationship on two F‐θ measurements at the same θ values. The experimentally determined F‐θ curve overlaps the theoretically calculated F‐θ relationship at high soil water contents and the empirically obtained F‐θ relationship at low soil water content. Examples are given for several soil types.
Calculating the Depths of Soil Moisture Control Sections from Laboratory Data
Authors: Zobeck T. M. , Daugherty L. A. 
Published: July 2010

AbstractCalculations of the upper and lower boundaries of a soil moisture control section are illustrated using only the depth, bulk density, and saturated, −1/3, and/or −15 bar water contents, and amount of coarse fragments of the soil horizons. It is recommended that the difference between the −50 to −100 cm and −15 bar water contents be used for determining and defining the soil moisture control section in medium to fine‐textured soils. Both moisture contents are reasonable approximations of physically or biologically significant moisture levels and easily determined in the laboratory. The definition would then correspond to the familiar available water‐holding capacity (AWC) value currently in use.
Stratified Profiles: Characteristics of Simulated Soils in a Beef Cattle Feedlot
Authors: Norstadt Fred A. , Duke Harold R. 
Published: July 2010

AbstractProfile combinations of clay loam, sand, clay loam over sand, and sand over clay loam were used to study salt movement and mineral nitrogen (N) transformations in a beef cattle feedlot. These soils were placed in lysimeters located in a feedlot stocked at the rate of one animal, weighing 270 to 450 kg, per 15.2 m2. The feedlot was bedded with sawdust and stocked continuously. After the lysimeters were in use 4 years, cores were removed for physical and chemical analyses. Each profile combination affected salt movement and mineral N transformations differently. Sand over clay loam was the superior combination to retard nitrate‐N (NO3‐‐N) movement and retain salt. In this configuration organic matter apparently moved from the manure pack through the sand along with NO3‐‐N and may have enhanced denitrification in the clay loam layer. The effect of location within the feedlot and depth increment within a given soil fill and their interaction were not important variables influencing profile chemical characteristics.
The Physical Swelling of Clays in Solvents
Authors: Murray R. S. , Quirk J. P. 
Published: July 2010

AbstractThe physical swelling of two illitic clays has been measured, at zero matric potential, in a series of organic solvents with different functional groups. The results show that a significant linear correlation exists between the observed swelling and the static dielectric constant of the liquid. This behavior is compared with the intracrystalline swelling of montmorillonite and is discussed in relation to the mechanism of swelling of clay systems.