bluuebunny/crossref_metadata_2025_split huggingface dataset:
Diffusion of Herbicides in the Adsorbed Phase
Authors: Scott H. D. , Phillips R. E. , Paetzold R. F. 
Published: July 2010

AbstractEquations were presented which describe the diffusion of the soil‐adsorbed herbicide phase. Assuming (i) no precipitation and volatilization, (ii) a linear adsorption isotherm, and (iii) no net change in herbicide concentration in the adsorbed phase, the data needed to make such a calculation can be determined experimentally and are as follows: soil bulk density, distribution coefficient, apparent self‐diffusion coefficient of the herbicide in soil, self‐diffusion coefficient of the herbicide in water and the transmission factor. The results indicated that the magnitude of the diffusion coefficient of metribuzin [4‐amino‐6‐tert‐butyl‐3‐(methylthio)‐as‐triazin‐5(4H) one] in Dubbs soil depends primarily upon the amount in the adsorbed phase and on the moisture content. The magnitude of the adsorbed phase diffusion coefficients of 14C‐metribuzin was less than the apparent self‐diffusion coefficients and decreased with decreasing soil water content. Since negative adsorbed phase diffiusion coefficients were observed at the lower soil water contents, the data suggested that the amount of metribuzin in the adsorbed phase increased as soil water content decreased.
Degradation of Argillic Horizons in Udalf Soils of New York State
Authors: Bullock P. , Milford M. H. , Cline M. G. 
Published: July 2010

AbstractInterfingering of albic material into the upper part of argillic horizons in Udalfs of New York is interpreted as evidence of degradation by loss of clay proceeding from the top of the horizon downward and from the surfaces of peds inward. These conclusions are based on: (i) albic material lacking oriented clay surrounding ped centers that contain oriented clay; (ii) the volume of albic material decreasing with depth; and (iii) the albic interfingering being least in soils in which high carbonate content is believed to have delayed clay translocation or weathering. The absence of clay skins in the degrading zone—in contrast with thick clay skins rich in fine clay at the Bt‐C horizon boundary—suggests that part of the clay removed at the top is translocated to the bottom of the B horizon. Smaller amounts of inherited mica clays and larger amounts of vermiculite, intergradient clays, and amorphous material in the clay fractions of degraded zones than in the remainder of B horizons indicates some weathering, but losses by this mechanism are believed small.
Splash Erosion: Some Observations on the Splash‐Cup Technique
Authors: Kinnell P. I. A. 
Published: July 2010

AbstractExperiments under artificial rainfall conditions showed that the initial, excessive loss from the type of splash cup frequently used in splash‐cup experiments was attributable not only to material being pushed sideways over the edge of the cup by the impact of drops near the perimeter of the exposed surface, but also to a decrease in the rate of splash loss.The amount of excess material lost during this initial period was not significantly influenced by the frequency of drop impact, but was significantly influenced by the force of drop impact. Consequently, it is unlikely that the effect was attributable to changes in the hydraulic conditions within the erodible material, but may have been attributable to changes in the roughness of the exposed surface. A calibration, specific to the size, shape and velocity conditions of the impacting drops, may therefore be required where the initial loss makes a significant contribution to the total loss from a splash cup. It is also probable that such a calibration may also be specific to the physical nature of the erodible material and to the hydraulic characteristics of the splash‐cup system.
Effect of Effluent from Beef Feedlots on the Physical and Chemical Properties of Soil
Authors: Hinrichs D. G. , Mazurak A. P. , Swanson N. P. 
Published: July 2010

AbstractEffluent from beef feedlots was applied as irrigation to a Colo silty clay loam soil in eastern Nebraska over a 2‐year period. Atlas sorghum [Sorghum bicolor L. (Moench.)] was grown in 1971 and 1972. Weekly irrigations applied during the growing season were: no effluent or water, 2.5 cm water from creek, 5.0 cm water from creek, 2.5 cm effluent, and 5.0 cm effluent. Surface soil samples were taken just before, midway, and at the end of each irrigation season.The effluent applications produced no statistically significant differences in soil bulk density, water‐retention characteristics, or size distribution of particles and water‐stable aggregates. Significant differences were measured in the hydraulic conductivities of disturbed soil samples. The effluent reduced the permeability of soil. The electrical conductivities and Na+, K+, and Cl‐ in the leachates obtained from hydraulic conductivity determinations for the effluent‐treated plots increased during the growing season. However, leaching from winter rains essentially eliminated these increases except for K+ which was greatly reduced.
Nitrate Production in Two Forest Soils and Nitrate Reduction in Pine
Authors: Theobald W. F. , Smith W. H. 
Published: July 2010

AbstractAcid forest soils showed low capacities for nitrification even when substrate NH4‐N was increased. Under forest soil pH conditions and NO3 levels typical of the lower coastal plain, pine roots (Pinus spp.) possessed low nitrate reductase (NR) activities.An in vivo assay showed NR activity in slash pine roots (P. elliottii Englm. var. ‘elliottii’). Activity depended on NO3 level and pH of nutrient solution. Highest activity was with 100 ppm NO3‐N at pH 6. Ammonium‐grown seedlings possessed low levels of activity even at pH 4, indicating constitutive nature or early induction of the enzymes. Radicles of seeds aseptically germinated actively reduced NO3, indicating activity within the root tissues. Daily patterns of fluctuation in NR activity similar to the pattern for photosynhesis were observed. In vitro assay attempts were unsuccessful, due apparently to the presence of inhibitors.
An Improved Procedure for Sampling the Atmosphere of Field Soils
Authors: Roulier M. H. , Stolzy L. H. , Szuszkiewcz T. E. 
Published: July 2010

AbstractAn improved gas probe for sampling the atmosphere of field soils and the equipment used to install it are described. The probe is easily inserted to depths of a meter or more without significant disturbance of the crop or soil and plugging by soil and water can be cleared without removing the probe from the soil. In medium‐ and coarse‐textured soils this system is more useful than other capillary probe sampling systems because of the method of installation, the strength of the probe, and the depth to which it can be inserted. In poorly structured, finetextured soils where gas samples are difficult to withdraw because of low air permeability, a well‐type probe is more satisfactory.
A Simple Gas Chromatographic Method for Separation of Gases in Soil Atmospheres
Authors: Blackmer Alfred M. , Baker J. H. , Weeks M. E. 
Published: July 2010

AbstractA simple method is described for the separation of mixtures of CH4, N2O, CO2, N2, and O2 in soil atmospheres using a single sample. This method uses two columns of Porapak Q at different temperatures but requires only one detector and recorder. Total analysis time is 23 min, but samples can be injected every 17 min without conflicting peaks.
Water Transport Through Plant Cells and Cell Walls: Theoretical Development
Authors: Molz Fred J. , Ikenberry Ernest 
Published: July 2010

AbstractAn increasing body of experimental evidence indicates that cell walls constitute an important pathway for water movement through plant tissues. Therefore, the present paper develops a mathematical description of water transport which allows for a water flux in the cell walls that does not necessarily traverse the cell membranes. The result is two coupled diffusion equations, one describing flow in the cell wall pathway and the other describing flow in the parallel cell to cell pathway. Using a resistance‐capacitance network analogy, the various parameters in the governing equations are identified as per cell resistances to water flow and per cell water capacities in and between the two parallel pathways.The theory is applied to a hypothetical water transport process in a sheet of plant tissue. A general closed‐form solution to the governing equations is obtained in the form of two double Fourier series, and realistic values are obtained from the literature for the various parameters. The theory predicts tentatively that water flows in the cell to cell and cell wall pathways will be comparable in magnitude and highly coupled, with each cell remaining in local equilibrium with the wall material external to its membrane. In this case, the overall transport process can be described by a single diffusion equation which is derived along with an expression for the free energy diffusivity of the combined pathways. The results of this study are in agreement with and bring together several past experimental studies by showing that a significant portion of the water flux traversing a plant tissue can occur in the cell wall pathway with the overall flow process still obeying simple diffusion kinetics. Whenever this occurs, the mathematical treatment of water transport in plant tissue will be simplified considerably.
Soil Strength and Porosities Associated with Cropping Sequences
Authors: Cary J. W. , Hayden C. W. 
Published: July 2010

AbstractThe effects of cropping sequences on the strength and porosity of the Portneuf silt loam soil were studied in south‐central Idaho under normal field conditions. Undisturbed soil cores were collected from the surface 20 cm of seven fields with cropping histories ranging from continuous pasture to continuous beans (Phaseolus vulgaris L.). The soil in all fields was a uniform silt loam developed under arid conditions. The pore size distribution and soil hardness were measured on the undisturbed cores as well as on bulk samples collected from each site. The results indicated that both the pore size distribution and the hardness are rather independent of cropping history. While both these parameters can be changed by mechanical manipulation, the soil soon reverts back to a stable range of values under field conditions.
Nitrification Inhibitor Studies of Soil in Field‐Buried Polyethylene Bags
Authors: Boswell Fred C. , Anderson O. E. 
Published: July 2010

AbstractSamples of Davidson scl soil, contained in polyethylene bags, were treated with N‐SERVE, a nitrification inhibitor, and buried during the course of fall bedding to a depth commensurate to normal practices for fall applied fertilizer. N‐SERVE effectively inhibited nitrification in these soil samples for a 4‐month period during winter and early spring whereas, in untreated samples, nitrification proceeded throughout the test and added NH4‐N was completely nitrified during the same period.
Determination of Wetting Front Suction in the Green‐Ampt Equation
Authors: Mein R. G. , Farrell D. A. 
Published: July 2010

AbstractInterest in the Green‐Ampt equation to predict infiltration rates into uniform and layered soils has increased in recent years. The work reported here is a study of the theoretical justification of determining the suction (at the wetting front) parameter in the equation from the hydraulic conductivity versus capillary suction relationship for the soil. It is shown that the wetting front suction so determined and used in a form of the Green‐Ampt equation which allows for the surface boundary condition initially being one of constant flux gives predictions of infiltration volumes comparable to those determined by numerical solution of the complex partial‐differential equation of moisture flow.
Nomographic Interpretation of Water Absorption Data in Terms of a Two‐Parametric Diffusivity‐Water Content Function
Authors: Stroosnijder L. , Bolt G. H. 
Published: July 2010

AbstractAn exponential extrapolation of a set of experimentally determined diffusivities, D as a function of water content, θ, into the region near saturation lead to an underestimate of the water absorption. A two‐parametric expression for the diffusivity as a function of θ, as proposed by Ahuja et al. (1972), is used to construct a nomogram. This provides a connection between the standardized D‐θ relationships according to Ahuja et al. and certain “integral” properties of the absorption wetting front. Good agreement is obtained between experimentally determined diffusivity values and the values derived from the nomographical interpretation of water absorption data. The present approach also lends itself to the construction of families of scaled wetting curves. Thus absorption behavior for different (uniform) initial moisture contents could be predicted adequately.
Ion Association in the Ammonia—Carbon Dioxide—Water System
Authors: Marion G. M. , Dutt G. R. 
Published: July 2010

AbstractThe stability constants for the ammonium bicarbonate and carbonate ion‐pairs were determined in dilute aqueous solutions. For the reaction, NH4 HCO30 ⇄ NH4+ + HCO3‐, K = 1.45. For the reaction, NH4CO3‐ ⇄ NH4+ + CO32‐, K = 4.54 × 10‐2. In the aqueous solutions examined, from 6 to 7% of the total nitrogen and from 6 to 12% of the total carbon were present as ion‐pairs.
Aluminum Content of Soil Extracts as a Function of pH and Ionic Strength
Authors: Misra U. K. , Blanchar R. W. , Upchurch W. J. 
Published: July 2010

AbstractThe concentration of aluminum in the soil extract cannot presently be predicted from ion activity product considerations alone. Aluminum concentration in solution can be estimated from pH and ionic strength of a soil extract by the following empirical equations
urn:x-wiley:03615995:saj2sssaj197403615995003800060020x:equation:saj2sssaj197403615995003800060020x-math-0001The aluminum concentration in the extracts of several soils were calculated using published data for pH and ionic strength and compared with the experimentally determined values.
Influences of Muleh Rate and Slope Steepness on Interrill Erosion
Authors: Lattanzi A. R. , Meyer L. D. , Baumgardner M. F. 
Published: July 2010

AbstractSoil and water losses from plots representing field areas between rills were studied for four rates of straw mulch at four slope steepnesses. Three simulated rainstorms totaling 2 hours at 6.4 cm/hour were applied to a 61‐ by 61‐cm test area of Russell silt loam soil.Interrill erosion was reduced about 40% by mulch applied at a rate of only 0.5 metric tons/ha and about 80% by 2 tons/ha, as compared with no mulch. Erosion was negligible at the 8 tons/ha rate. Soil losses from the interrill areas at 20% slope were only about double those measured at 2% slope, whereas widely used erosion equations show that total field erosion would increase about 20‐fold over this range of steepnesses.Water loss by runoff was independent of slope steepness, but it was slightly reduced by mulch at a rate of 2 tons/ha and was greatly reduced by the 8 tons/ha rate. After 40 minutes of rainfall, sealing of the soil surface by raindrop impact had reduced infiltration rates for treatments with 0 to 2 tons/ha of mulch to only 20% of those with 8 tons/ha.
Site Factors and the Net Primary Productivity of Young Loblolly Pine and Slash Pine Plantations
Authors: Nemeth J. C. , Davey C. B. 
Published: July 2010

AbstractThe relationship between site factors and net primary productivity of young plantations of loblolly pine (Pinus taeda L.) and slash pine (Pinus elliottii Engelm.) in Beaufort County, North Carolina were investigated. Exchange acidity, cation exchange capacity, pH, Mg, and K of these Ultisol and Alfisol soils of the fine‐loamy, mixed, thermic family were found to be correlated (P = 0.05) with the net primary productivity of loblolly pine. The net primary productivity of slash pine was correlated with cation exchange capacity (P = 0.05).
Effects of Phosphorus on Some Physical and Chemical Properties of Clays
Authors: Lutz J. F. , Haque Inamul 
Published: July 2010

AbstractMontmorillonite, kaolinite, and a 1:1 mixture of them were treated with phosphorus at rates as high as 1,600 ppm using phosphoric acid and monocalcium phosphate. After 3 months the clays were examined for pH, zeta potential (charge), swelling, hydration in suspension, modulus of rupture of briquets, and water retention at 5 and 15 bars pressure. The H3PO4 decreased pH in all clays; the CaH4(PO4)2 decreased it in montmorillonite and in montmorillonite‐kaolinite, but increased it in kaolinite. Both sources of phosphorus caused alternate increases and decreases in the charge of the clays at rates up to 200 ppm and swelling and hydration of the clays were closely correlated to the charge. In general, water retention at 5 bars alternately increased and decreased with increasing rates of phosphorus but did not always exactly parallel the changes in charge, hydration, and swelling. The highest rate (1,600 ppm) caused a significant decrease in the 5‐ and 15‐bar percentages in all instances except the H3PO4 on kaolinite. This exception may have been due to chemical alteration of the kaolinite produced by the very low pH. Modulus of rupture was significantly reduced by both sources of phosphorus. Essentially all of the P‐induced physical and chemical changes would be beneficial in agricultural soils, and they are economically important because the greatest changes were produced by feasible rates of phosphorus.
Bonding of Calcium and Potassium by Vermiculite and Kaolinite Clays as Affected by H‐clay Addition
Authors: Baweja A. S. , McLean E. O. 
Published: July 2010

AbstractThe < 2 µm fraction of Libby vermiculite and Peerless kaolinite was separated and H‐saturated by resin treatment. The H‐clay suspensions were immediately saturated with either Ca or K by addition of the respective hydroxides. Six reciprocal Ca‐K saturations of each clay were prepared by mixing the Ca‐ and K‐clays in appropriate amounts. Increments of H‐clay were added to lower the base saturation and thereby inactivate the pH‐dependent charges. Radioisotopes, 45Ca and 86Rb, were used as tracers for Ca and K, respectively. Two‐phase Donnan‐type systems were prepared and equilibrated for 23 days. Radioactivity in both phases was then assayed and the amounts of Ca and K retained in the suspension phases of the two clay systems computed.The pH‐dependent fraction of the total CEC was 6.9 and 18.0% for vermiculite and kaolinite, respectively. Additions of H‐clay increased the bonding of both Ca and K as indicated by greater clay‐phase retention. However, maximum retention of the cations at all Ca‐K saturation ratios did not occur when the amounts of H‐clay added equaled the pH‐dependent charge fraction of the clay as had occurred with bentonite and illite.
Boron, Calcium, and Potassium Interactions in Spanish Peanuts
Authors: Hill W. E. , Morrill L. G. 
Published: July 2010

AbstractExperiments were conducted in the field and greenhouse to evaluate interactions between application of B, Ca (gypsum) and K upon yield and quality of ‘Comet’ variety Spanish peanuts (Arachis hypogaea). In the greenhouse, using Eufaula fine sand, peanuts received factorial treatment combinations of three rates of B (0, 0.25, and 0.50 ppm), three rates of Ca (0, 88, and 176 ppm as gypsum), and three rates of K (25, 50, and 100 ppm). Factorial treatment combinations of three rates of B (0, 0.56, and 1.12 kg/ha), and three rates of Ca (0, 65, and 130 kg as gypsum/ha) were applied under field conditions at three locations.Under greenhouse conditions, significant interactions between the effects of B and Ca on growth and quality were observed. High Ca levels in the absence of applied B resulted in increased yields, lower seed quality (percent sound mature kernels), and extremely large increases in amounts of internal damage (due to B deficiency). No significant difference in yield response to B and Ca applications were found under field conditions. Peanuts showed a significant B by K interaction. Application of B with rates of potassium resulted in small increases in yield, except at the highest B and K levels where yields were reduced.
The Nitrogen Status Beneath Beef Cattle Feedlots in Eastern Nebraska
Authors: Ellis J. R. , Mielke L. N. , Schuman G. E. 
Published: July 2010

AbstractSoil cores (129) were taken from 15 eastern Nebraska feedlots in the Elkhorn and Platte river valley areas. The sites represented a wide range of conditions from small farm feedlots to large commercial operations.Most feedlots did not constitute a nitrate pollution hazard to ground water. Upland feedlots, with slopes >5%, contained less than 10 ppm NO3‐‐N in the ground water; however, slopes <5% had increased frequency of NO3‐‐N in the ground water. Only one river‐valley feedlot ground‐water sample exceeded 10 ppm NO3‐‐N. Problems of ground water with > 10 ppm NO3‐‐N were localized. The feedlot and cropland conditions examined and ranked according to decreasing average NO3‐‐N in the core were: abandoned feedlot > feedlot‐cropland > upland feedlot > corn (Zea mays L.) > river‐valley feedlot > profiles under feedlot mounds > alfalfa (Medicago sativa L.) > grassland.
Fertilizer or Salt Leaching as Affected by Surface Shaping and Placement of Fertilizer and Irrigation Water
Authors: Kemper W. D. , Olsen John , Hodgdon Alan 
Published: July 2010

AbstractIrrigation in furrows and placement of fertilizer in bands in ridges was evaluated as a means for allowing overirrigation to bypass nitrate and reduce leaching losses. In a loamy sand, placement of band 0 to 5 cm higher than the surface of water in the furrow allowed over 120 cm of overirrigation before the salt began to leave the root zone. In the clay loam a similar delay of nitrate removal was not achieved until the band was 10 cm higher than the water surface. This difference appeared to be associated with a perched water table that developed in the “cultivated” layer of the clay loam soil due to higher hydraulic conductivity in cultivated than in the lower soil.Downward movement of relatively concentrated salt solution near the band, due to its greater density, was a factor that allowed fertilizer bands at lower levels to enter the mainstream of the leaching water.Leaching of fertilizer from a soil can be delayed by placing it in ridges and irrigating in furrows rather than broadcasting fertilizer followed by flood irrigation. The practical significance of nitrate staying in the root zone longer as a function of such water and fertilizer management should be tested in the field.
Black Spruce Site Quality as Related to Soil and Other Site Conditions
Authors: Lowry G. L. 
Published: July 2010

AbstractSite factors were studied in relation to site index in 125 black spruce (Picea mariana Mill. BSP.) stands of eastern Canada. Site index was higher in the Continental than in the Atlantic Region, apparently due to differences in effective solar energy. In both regions site quality was related primarily to soil moisture and nutrients. Site index is better on freely drained, mesic mineral soils. These sites have modest humus accumulations. Soil analyses indicate that nitrogen and phosphorus limit tree growth over a broad range of site conditions. Few of the factors studied appear to have site index prediction value. However, many were suitable for site classification purposes. For extensive mapping of site productivity the primary framework should be landform and associated soils and geologic formations. Within this classification, moisture regime and nutrient regime may be included.