bluuebunny/crossref_metadata_2025_split huggingface dataset:
Soil Air Pressure and Water Infiltration Under Border Irrigation
Authors: Dixon R. M. , Linden D. R. 
Published: July 2010

AbstractSoil air pressure and water infiltration were measured during actual and simulated border irrigation of a uniform loam soil having a water table about 2 m beneath the surface. These measurements were made with instrumentation specifically designed to distinguish between displaced and entrapped air; to separate hydraulic and pneumatic pressure sources; and to isolate infiltration effects of displaced air pressure. Displaced air pressure decreased downslope and across slope from center to edge of the border strips. A maximum displaced air pressure of 21 cm of water was observed in the upslope central part of the border strip. Air entrapment commonly occurred at a 50‐cm depth next to border dikes but rarely occurred midway between dikes, which implies that water penetration was greatest in the region of lowest displaced air pressure. Infiltration measurements, made under actual and simulated border irrigation, indicated that displaced air pressure, building to a maximum of about 19 cm, reduced total infiltration by about ⅓. Such pressure appears to impede infiltration mainly by preventing or retarding direct flow of surface water into and within open macropores. In the central region of the border strip where displaced air pressure exceeds the surface water head, macropores vent displaced soil air upward; whereas along the border dikes where surface head exceeds air pressure, macropores conduct free surface water downward. A leaking‐system form of Boyle's Law is used to interpret typical displaced air pressure‐time curves and to suggest possible ways of controlling displaced air pressure. This research implies that soil air pressure and its infiltration effects are not negligible as is commonly assumed by Darcy‐based flow theory and that soil air can be a useful tool for controlling infiltration in some important situations.
A Conveniently Constructed Divisor for Splitting Low Water Flows
Authors: Coote D. R. , Zwerman P. J. 
Published: July 2010

AbstractFor monitoring the quality of water running off agricultural land it is necessary to obtain representative and conveniently small samples of water. A divisor has been designed for attachment to a Coshocton wheel to enable small samples to be collected. The materials cost for the divisor described in this note is $2. A skilled technician, equipped with adequate tools, can construct and install the divisor in 4 hours.
Artificial Weathering of Oxidized Biotite: II. Rates of Dissolution in 0.1, 0.01, 0.001M HCl
Authors: Gilkes R. J. , Young R. C. , Quirk J. P. 
Published: July 2010

AbstractRates of dissolution of biotite in 0.1, 0.01, 0.001M HCl decrease as the proportion of ferric iron in octahedrally coordinated sites increases. This is interpreted as being partly due to a decrease in the rate of K exchange from oxidized biotite so that a smaller surface area is exposed to acid attack. The availability of structural cations (Mg, Mn, Zn, K, etc.) to plants growing on biotite rich soils will be a function of the oxidation state of structural iron in the biotite.
Infiltration and Water Table Effects of Soil Air Pressure Under Border Irrigation
Authors: Linden D. R. , Dixon R. M. 
Published: July 2010

AbstractField studies investigated infiltration and water table responses to soil air pressure under border irrigation. The water table was depressed in the center and elevated near the edge of a border strip in response to differences in soil air pressure during an irrigation. Also, water table elevations indicated that infiltration and subsequent groundwater recharge rates were greater in the vicinity of a border dike than at the center of the border. An infiltration response was measured by: (i) venting soil air during an actual irrigation and (ii) pumping air into the soil during simulated irrigations. An actual border irrigation experiment indicated that displaced soil air pressure ha (expressed as equivalent heads of water) rising to values of 13 to 24 cm of H2O reduced infiltration over a 70‐min period from 14.3 to 10.3 cm. Simulated border irrigation experiments indicated that displaced soil air pressure ha must exceed surface head hs to have significant influence on infiltration and that the first few minutes of infiltration may determine the ha‐to‐hs relationship and subsequent infiltration effects. In the simulated irrigations with hs = 6.3 cm, total infiltration in 1 hour was 6.0 and 1.5 cm when ha was 0 and 10 cm of H2O, respectively. Infiltration was only slightly reduced during the first 5 min when ha was 5 cm of H2O.
Mathematical Evaluation of Factors Affecting Gully Stability
Authors: Bradford J. M. , Farrell D. A. , Larson W. E. 
Published: July 2010

AbstractBecause large amounts of sediment come from gully banks in the coarse loess soils of the Lower Missouri River Basin, a study was made of the factors influencing the stability of gully banks. The approach was to consider the action of forces within the soil mass forming the wall of the gully. A two‐dimensional stability analysis was made using the Simplified Bishop Method of Slices.If the angle of internal friction is ≤ 35°, calculated factors of safety indicate that vertical, saturated, or near‐saturated gully walls in loessial soils will fail if a ground water table exists at the base of the wall and if the cohesion for the saturated soil system is zero at a hydrostatic pressure of zero. Although gully bank stability is sensitive to the angle of internal friction, the calculated stability is relatively insensitive to slope height and soil bulk density. Tension cracks that frequently open at some distance back from the gully face do not materially influence stability. The effect of infiltration rate into the soil on the stability of the gully wall depends upon the rate of water conductivity through the soil and upon the cohesion of the soil or the level of the ground water table. Increasing the infiltration rate decreases the stability.
Analytical Solution of the Convective‐Dispersive Equation for Cation Adsorption in Soils
Authors: Cleary Robert W. , Adrian Donald Dean 
Published: July 2010

AbstractThe analytical solution of a cation adsorption soil problem is derived in detail by an integral transform method. The solution applies to the case of unsteady‐state, one‐dimensional flow through soils where a linear equilibrium exists between the cation in the flowing solution and the cation adsorbed on the exchanger phase. The effects of axial dispersion are also included in the solution.
Physiological Aspects of Iron‐Phosphorus Nutrition in Two Varieties of Maize: I. Uptake and Accumulation Characteristics Under Greenhouse and Field Conditions
Authors: Estes G. O. , Bruetsch T. F. 
Published: July 2010

AbstractTwo varieties of corn (Zea mays L.) showed differences in efficiency of Fe utilization when grown in hydroponic solutions and under field conditions. Under hydroponic conditions, ‘Seneca XX155’ showed greater susceptibility to P‐induced Fe stress than ‘Wisconsin 335A’, although its foliage contained more Fe. This susceptibility was related to reduced Fe translocation caused by relatively high P concentrations. Levels of P > 22 ppm in the nutrient solution produced significant reduction in foliage Fe of both varieties. Field studies showed significant reduction of tissue Fe at a fertilization level of 50 kg/ha compared to controls. Unlike results from hydroponic studies, no change in Fe status occurred at progressively higher rates of applied P (50–400 kg/ha) under field conditions. Levels of tissue Fe were never < 160 ppm following soil P applications.
Quantifying Pedogenesis for Soils with Discontinuities
Authors: Wang Chang , Arnold R. W. 
Published: July 2010

AbstractComparing calculated values of changes with observable features in relatively young soils is one way of testing genetic assumptions. If the agreement is acceptable, then the probability that the assumptions are correct increases. Two sites similar in most properties other than initial carbonate content of parent materials were examined and found to also have similar lithologic discontinuities. Soil development across parent material boundaries necessitates additional judgments about the initial state, consequently different trends of bulk density and selected mobile and immobile constitutents were estimated for each material in each profile and changes in the systems calculated. The reported values are not based on vertical homogeneity, and yet the changes seem to correspond to, and be supported by, morphological observations. It is concluded that this Hapludalf and this Fragiochrept developed under similar soil systems.
Collapsible Loess in Iowa
Authors: Handy Richard L. 
Published: July 2010

AbstractThe collapsibility, or tendency towards rapid consolidation or settlement upon saturation by water, of many C‐horizon loess soils constitutes and important physical property pertinent to soil genesis, erosion, and engineering. The potential of a loess soil to collapse upon saturation by water may be established from undisturbed samples saturated while under load in a consolidation testing machine. A more convenient criterion, that the saturation moisture cntent must not exceed the liquid limit, was regressed against 0.005 mm clay content determined by the hydrometer method, and indicated that C‐horizon loess containing less than 20% 0.005 mm clay is very likely to be collapsible; with 30% clay there is a 50% probability of collapse, and with over 40% clay there is only a small likelihood of collapse. These percentages were compared to published clay content contours to estimate the areal extent of collapsible loess in Iowa. To convert to 0.002 mm clay content, hydrometer test 0.005 mm clay contents were regressed against pipette test 0.002 mm clay contents to give X002 = 0.8X005; thus the 0.002 mm clay contents corresponding to high, medium, and low probabilities of collapse are < 16%, 24%, and > 36% caly, respectively.
Soil Mulch Effects on Seedbed Temperature and Water During Fallow in Eastern Washington
Authors: Papendick R. I. , Lindstrom M. J. , Cochran V. L. 
Published: July 2010

AbstractDepth of dry soil mulch affected summer soil temperatures and seed‐bed water at the end of fallow in the dryland wheat region of eastern Washington. Increasing the depth of the tillage mulch from 6 to 11 cm reduced summertime seed zone drying sufficiently to benefit wheat emergence. Reduction of drying was greatest when the seed zone had good capillary continuity with the deeper soil layers. Drying depth and intensity was greater with a cloddy soil mulch than with a fine mulch.The seed zone water‐conserving effect of a fine soil mulch was related to the lowered temperatures and temperature gradients across the seed zone associated with the increased mulch depth. The deeper soil mulch conserved seedbed water through increased resistance to water flow from moist layers to the atmosphere, and through increased thermal insulation of the moist soil below the dry mulch. Surface‐applied straw (4,000 kg/ha) decreased seed‐zone temperatures under the shallow mulch only.The key factor in conserving seedbed water through extended periods of hot, dry weather is that the loss rates from the seed zone be balanced by upward unsaturated flow from deeper layers. As the soil dries, the relative importance of loss rates through evaporative loss across the dry layer and thermally induced flow downward increases because of decreasing return flow from the deeper layers along matric potential gradients. Under these dryland conditions, it appears that seedbed water could be best conserved through using a soil mulch of maximum resistance to vapor and liquid water flow, and maximum thermal insulation, overlying a seed zone having good capillary continuity with the deeper soil layers. The stratification produced by moderately deep rod‐weeding appears to provide such a mulch.
Encasing Undisturbed Soil Cores in Plastic
Authors: Mielke Lloyd N. 
Published: July 2010

AbstractA technique was developed using a 10.2‐cm‐diameter soil sampler to obtain undisturbed soil cores encased in heat‐shrinkable tubes. Six cores were taken in feedlots, five from sandy loam, and one from a silty clay loam. The undisturbed soil core is placed inside the plastic tube during the sampling operation, thereby minimizing core handling and possible fracture.
Nature of Phosphorus Retention and Adsorption with Depth in Soil Columns
Authors: Logan T. J. , McLean E. O. 
Published: July 2010

AbstractSequential fractionation of adsorbed 32P and changes in equilibrium P concentration (EPC) with depth were studied in a column leaching experiment. In general, the percentage of NH4Cl‐extractable P decreased rapidly with depth; the percentage of NH4F‐extractable P decreased rapidly in the initial 2‐cm depth and then remained fairly constant. Percentage NaOH‐extractable P increased as that of NH4F‐extractable P decreased, and that of H2SO4‐extractable P increased gradually with depth.Equilibrium P concentration (EPC) decreased with depth and increased as rate of P applied increased. These EPC values reflected both depth of penetration of applied P and level of native P in the soil.
Kinetics of Isotope Exchange on Hydroxyapatite
Authors: Kukura M. , Bell L. C. , Posner A. M. , Quirk J. P. 
Published: July 2010

AbstractThe kinetics of exchange of 32P and 45Ca in aqueous solution with synthetic, stoichiometric hydroxyapatitie was followed up to 200 hours. Seventy percent of the total exchange occurred in 1 hour, and isotopic equilibrium was reached at approximately 40 hours. Using McKay (13) plots, the exchange reaction was shown to be heterogeneous. Diffusion of isotope through solution “compartments” was considered to be rapid in relation to exchange occurring at the solid surface. The nature of the exchange curve was explained by the differing energies of activation of exchange for surface atoms located at different positions on the crystal landscape. The use of well‐crystallized, stoichiometric hydroxyapatite resulted in the establishment of a well‐defined isotopic equilibrium (11) with little evidence of loss of isotope through intracrystalline diffusion or recrystallization.
Diffusion of Zinc in Soils as a Function of Applied Zinc, Phosphorus, and Soil pH
Authors: Melton James R. , Mahtab Samuel K. , Swoboda Allen R. 
Published: July 2010

AbstractSelf‐diffusion coefficients, D, of 65Zn were determined in two Texas soils. In the Norwood loam, a calcareous soil of pH 8.2, the effect of applied P and Zn on diffusion coefficients was studied. As the applied P was raised from 0 to 240 ppm, the D value obtained at 0 ppm Zn decreased significantly from 11.73 × 10‐11 to 8.57 × 10‐11 cm2/sec; at 40 ppm Zn, the D value decreased significantly from 28.51 × 10‐11 to 16.33 × 10‐11 cm2/sec. Zinc diffusion doubled as the applied Zn was increased from 0 to 40 ppm at all levels of applied P. In the Nacogdoches sandy loam, a soil initially of pH 6 but subsequently raised to pH 7.2 and 7.9 by liming, there was little difference between the D values obtained at pH 7.2 and 7.9. When the applied Zn was increased from 0 to 20 ppm, the D value increased from 5.35 × 10‐11 to 7.83 × 10‐11 cm2/sec at pH 7.2 and from 3.97 × 10‐11 to 6.26 × 10‐11 cm2/sec at pH 7.9. However, D values obtained at pH 6 were much larger than those obtained at pH 7.2 and 7.9. As the Zn level was raised from 0 to 20 ppm at pH 6, the D value increased from 19.90 × 10‐11 to 19.53 × 10‐9 cm2/sec. It appears from this study that the effect of Zn and pH on diffusion of Zn is greater than that of applied P.
Impact of Earthworm Introduction on Litter Burial and Nutrient Distribution in Ohio Strip‐Mine Spoil Banks
Authors: Vimmerstedt John P. , Finney James H. 
Published: July 2010

AbstractEarthworms (Lumbricus terrestris L.) actively buried leaf litter and humus, and deposited castings on the surface of an acid (pH 3.5–4.0) shale spoil bank revegetated with black locust (Robinia pseudoacacia L.). Earthworms persisted for 5 years in the coal spoils and buried or consumed the equivalent of 5 metric tons of leaf litter/ha. In a greenhouse study, earth‐worms in cores of spoil from the mined area buried or consumed a 60‐mm thick layer of litter and humus in 174 days. The equivalent of 9.5 metric tons of litter and 52.5 metric tons of humus was buried or consumed/ha, while the equivalent of 16.7 metric tons of castings was deposited on the surface. Exchangeable cations and available P in the mineral spoils increased as follows: K from 0.17 to 0.19, Ca from 1.7 to 2.7, and Mg from 1.8 to 2.5 meq/100 g of spoil; and available P increased from 1.7 to 4.2 ppm. Earthworm activity did not influence growth of northern red oak (Quercus rubra L.) seedlings planted in the cores.In another study, 10 Lumbricus terrestris were introduced on a calcareous strip‐mine spoil revegetated with European alder (Alnus glutinosa L.). In 5 years, the earthworm population increased to a density of 60 middens/m2 over an area of 700 m2.Clearly, earthworms can be established on revegetated coal spoil banks, where they promote incorporation of organic matter into the mineral spoil.
Inhibition of Nitrification in Soils
Authors: Bundy L. G. , Bremner J. M. 
Published: July 2010

AbstractThe effectiveness of 24 compounds proposed as inhibitors of nitrification in soils was studied by determining the effects of 10 ppm (soil basis) of each compound on the amounts of nitrate and nitrite produced when soils treated with ammonium sulfate (200 ppm of ammonium N) were incubated at 30C for 14 days. With the soils used, the average effectiveness of the most potent inhibitors decreased in the order: 2‐chloro‐6‐(trichloromethyl)‐pyridine (N‐Serve) > 4‐amino‐1,2,4‐triazole (ATC) > sodium or potassium azide > 2,4‐diamino‐6‐trichloromethyl‐s‐triazine (CL 1580) > dicyandiamide > 3‐chloroacetanilide > 1‐amidino‐2‐thiourea > 2,5‐dichloroaniline > phenylmercuric acetate > 3‐mercapto‐1,2,4‐triazole or 2‐amino‐4‐chloro‐6‐methyl‐pyrimidine (AM) > sulfathiazole (ST) > sodium diethyldithiocarbamate. The other compounds tested (gallic acid, cysteine, cystine, methionine, methionine sulfoxide, methionine sulfone, ethionine, thiourea, 1‐allyl‐2‐thiourea, and 2‐mercapto‐benzothiazole) had little or no effect on nitrification of ammonium in soils under the conditions studied.The effectiveness of the inhibitors studied was markedly affected by soil type, soil temperature, and substitution of urea for ammonium sulfate as the source of nitrifiable nitrogen. Most of the inhibitors were considerably more effective at 15C than at 30 C.
Phosphorus Losses from Four Agricultural Watersheds on Missouri Valley Loess
Authors: Schuman G. E. , Spomer R. G. , Piest R. F. 
Published: July 2010

AbstractPhosphorus losses from four field‐size experimental watersheds at Treynor, Iowa, were measured during 1969, 1970, and 1971. A contour‐planted corn watershed and a pasture watershed were fertilized at the recommended P rate (39 kg/ha). A level‐terraced and a second contour‐planted corn watershed were fertilized at 2.5 times this rate. At the high level of P fertilization, phosphorus loss by surface runoff from the contour‐planted corn watershed was 0.495 kg/ha in 1969, 1.034 kg/ha in 1970, and 2.130 kg/ha in 1971. Level terraces greatly reduced P loss by reducing runoff and erosion.Water samples for all runoff events taken above the overfall of each watershed gully contained considerably more inorganic P in solution than samples taken at the weir site, 70 to 230 m downstream. This reduction in solution P was caused by the adsorption of P by the additional suspended soil material entering the stream from gully erosion.
Automated Repetitive Short‐Term Extraction of Soil Samples
Authors: Ballaux Jean‐Claude , Peaslee D. E. 
Published: July 2010

AbstractStudies of P release during short contact times between soil and extractant were conducted on soils with an automatic sequential extracting apparatus. Varying contact times between the soil and extracting solution can be set by an adjustable multigang timer of 20‐min cycle. Data for two soils of different textures show marked differences in P extraction. The apparatus appears adaptable for evaluating short‐term release of other ions and pesticides from soils.
Automated Total Nitrogen Analysis of Soil and Plant Samples
Authors: Schuman G. E. , Stanley M. A. , Knudsen D. 
Published: July 2010

AbstractSoils research dealing with environmental quality requires the analysis of large numbers of samples to better characterize the problem. An automated technique, using a Tecator digester and Technicon AutoAnalyzer, has proved to be as reliable as the standard micro‐Kjeldahl procedure and permits more rapid analysis of the digests (30 per hour). The system is compact and involves fewer steps for analytical error.
A Mathematical Investigation of Steady Infiltration from Line Sources
Authors: Zachmann David W. , Thomas Adrian W. 
Published: July 2010

AbstractThe objective of this study is to develop equations which can be used in the design of subsurface irrigation systems. This first paper deals with the physics of steady infiltration from a distribution of line sources which lie in a horizontal plane and are parallel and equally spaced. The analytical solution describes the flow from the line sources in the presence of uniform infiltration or evaporation at the soil surface. To increase the utility of the solution, the equations for matric flux potential and stream function are written in dimensionless form.
Response of Salinity Sensors to Rapidly Changing Salinity
Authors: Wesseling J. , Oster J. D. 
Published: July 2010

AbstractBased on the assumption that diffusion of solutes into and out of the sensitive element of a salinity sensor determines its response time, a theory was developed to describe the response of the sensor to changes in soil salinity. This theory was experimentally verified in solution and in soils. The response of a sensor was shown to be adequately described by a single response factor. Proper use of this factor permits the actual electrical conductivity of the soil solution to be inferred from sensor readings where soil salinity changes rapidly.
Land Sale Prices in South Dakota and Their Relationship to Some Soil, Climatic, and Productivity Factors
Authors: Westin F. C. , Stout M. , Bannister D. L. , Frazee C. J. 
Published: July 2010

AbstractAbout 2,700 land sale figures were used along with individual county soil‐association maps to determine average peracre values of South Dakota counties. Annual average precipitation and temperature data were connected to landsale figures using multiple‐regression equations. County crop productivity also was related to precipitation and county land sale data. The best prediction formula for explaining average county land values was a fifth‐order polynomial‐regression with precipitation as the variable. This explained 95% of the variance. Most of the variance (84%) of county cropland productivity was explained with a second‐order polynomial‐regression having annual‐average precipitation as the variable, and 86% of the variance of county land value figures was explained with a second‐order polynomial‐regression having county cropland productivity as the variable. However, only a little over 54% of the variance of individual farm sales could be explained using regression equations involving climate, slope, and soil‐texture as variables.