bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determination of Soil Water Diffusivity by Sorptivity Measurements
Authors: Dirksen C. 
Published: July 2010

AbstractA new method is proposed for determining the dependence of soil water diffusivity and conductivity on water content or pressure head in the tensiometer range. A weighted mean diffusivity is used to linearize the one‐dimensional absorption problem. The resulting cumulative absorption is equated to that of the exact nonlinear solution to obtain an expression for the diffusivity in terms of sorptivity. To use this result, sorptivities must be measured for a series of step‐function increases in the water content (pressure head) at the absorption interface. Such sorptivity measurements are quickly and easily made in situ.The method was tested on a numerical example with nearly perfect results. Also, sorptivity measurements were made on laboratory soil columns and the derived hydraulic conductivities compared well with those measured directly under steady state conditions.
Evaluation of Soil Testing Methods for Predicting Growth and Response of Pinus elliottii to Phosphorus Fertilization
Authors: Ballard R. , Pritchett W. L. 
Published: July 2010

AbstractSoil tests were evaluated as methods for predicting height growth or increased height growth due to P fertilization of Pinus elliottii var. elliottii Engelm. on acid Coastal Plain soils. Growth and response parameters were obtained from field and greenhouse trials fertilized at time of planting with N and P. Field trials were measured 1, 3, and 5 years after planting and the greenhouse trial, which involved unfertilized soils collected from the field trials, was measured 1 and 2 years after planting.The amounts of P extracted by H2O or NH4OAc (pH 4.8) were the most closely correlated with height growth and response to P fertilization after 1 year of growth in both the greenhouse and field. The effectiveness of these methods declined after longer growth periods. Methods which extracted larger amounts of P—0.5M NaHCO3; 0.05N HCl + 0.025N H2SO4; 0.03N NH4F + 0.025N HCl—were more effective predictors of response to P fertilization over growth periods of 3 and 5 years in the field. Phosphorus extracted by 0.03N NH4F + 0.025N HCl was the most closely correlated with response recorded after 5 years (r2 = 0.778).Concentrations of P in the tops of greenhouse‐grown pine seedlings after both 1 and 2 years growth were most closely related to P removed by the stronger extractants. The r2 values for the relationships between soil test values and both concentrations of P in seedling tops after 2 years and in foliage of field trees at age 4 were almost identical.
Effects of Fertilization and Thinning on the Growth of Ponderosa Pine
Authors: Youngberg C. T. 
Published: July 2010

AbstractOver much of its range second growth ponderosa pine (Pinus ponderosa Laws.) occurs in greatly overstocked stands which, in combination with low annual precipitation, results in large unproductive areas. This study explored thinning and fertilizer application as a means of increasing timber production. Nitrogen, P and K were applied to thinned and unthinned stands of 45‐year‐old pine. Growth measurements after 5 years revealed fertilizer response in both thinned and unthinned stands. Responses in the latter were significant but small. Main fertilizer effects were from N. Thinning effects were greater than fertilizer effects and a combination of thinning and fertilizers gave the best growth response. Even though additional N was applied, growth at the end of the second 5‐year period had decreased, indicating that the thinned stand was still overstocked.
Ammonia Retention in Tropical Soils as Influenced by Moisture Content and Continuous Submergence
Authors: Shimpi S. S. , Savant N. K. 
Published: July 2010

AbstractUnder laboratory conditions, when moisture contents increased from 0 (oven‐dry) to 30%, amount of NH3 retained in noncalcareous medium black soil and lateritic soil decreased. However, subsequent increase in moisture content from 30 to 100% resulted in increased NH3‐retention in the soils. Continuous submergence favored NH3‐retention in the soils.
On Solving the Flow Equation in Unsaturated Soils by Optimization: Horizontal Infiltration
Authors: Parlange Jean‐Yves 
Published: July 2010

AbstractRecently, integral methods have been developed that provide accurate approximations to the diffusion equation with rapidly varying diffusivity, but require in general some numerical iteration. In the present paper, a new analytical approach is developed which yields optimal approximations without any numerical iteration. The method is applied to the problem of one‐dimensional horizontal infiltration of water in soils. In that case it is shown that the sorptivity is an invariant, which can be expressed in terms of the sum of two integrals involving the diffusivity. The analytical results are in excellent agreement with numerical calculations for Yolo light clay.
Dissolution Rate of Gypsum in Flowing Water
Authors: Kemper W. D. , Olsen John , de Mooy C. J. 
Published: July 2010

AbstractDissolution rates of gypsum were measured in water flowing through beds of gypsum fragments as affected by fragment size, solution velocity and initial concentrations of Ca2+, SO42‐ and CO32‐ in the flowing water.Equations were derived to describe the rates of dissolution, and a dissolution coefficient was defined which is a function of fragment size and solution velocity. Rates of dissolution are high enough to distribute quantities of gypsum, which are within economic reach of the farmer, on farm lands via the irrigation water. Sample calculations are made to show how these data may be used to design watercourse cross sections for applying given levels of gypsum to the flowing water.
The Relationship between Organic Matter Content and Exchangeable Aluminum in Acid Soil
Authors: Thomas Grant W. 
Published: July 2010

AbstractVarying amounts (0–20 meq/100g) of nitric acid were added to samples from six depths of a Maury silt loam which varied in organic matter content from 5.11 to 0.80%. Aluminum extracted by 1N KCl was found to be lower as organic matter content increased at any given pH level. This finding helps to explain the successful growth of crops in killed sods where the surface soil is acid but rather high in organic matter; it also may account for some of the benefit of organic amendments on acid soils.
Model of Soil Salinity Effects on Crop Growth
Authors: Childs S. W. , Hanks R. J. 
Published: July 2010

AbstractThe model considers properties of the soil, water, plant, and atmospheric system to predict relative crop yield. Crop yield predictions assume a direct relation between dry matter production and transpiration. The only salinity effects considered are osmotic potential. The influence of initial soil salinity on crop growth depended upon the crop type and irrigation management. Predictions made of salt buildup over several years show that some water management systems would produce high yields for several years before salt buildup would decrease yields. Predictions show that the influence of irrigation system uniformity on salinity buildup and yield reduction is very important.
Interactions Between Organic Compounds, Minerals, and Ions in Volcanic‐ash‐derived Soils: I. Adsorption of Benzoate, p‐OH Benzoate, Salicylate, and Phthalate Ions
Authors: Appelt H. , Coleman N. T. , Pratt P. F. 
Published: July 2010

AbstractThe adsorption, desorption, and competitive adsorption characteristics of benzoate, p‐OH benzoate, salicylate, and phthalate were used as models to study the possible mechanisms involved in the interactions of organic compounds with amorphous materials. The studies were carried out in batch systems using subsoil samples of three Typic Dystrandept soils from Chile.The adsorption of simple organic anions by soils derived from volcanic‐ash can be described by an adsorption‐pKa‐pH relationship. The removal of organic matter with H2O2 did not affect the adsorption of organic anions. The adsorption characteristics obtained, together with desorption and competitive studies, suggest that benzoate was adsorbed by an anion‐exchange reaction by volcanic‐ash‐derived soils. But p‐OH benzoate, salicylate, and phthalate besides anion‐exchange adsorption, were also adsorbed by ligand‐exchange reactions. It is postulated that chelation ability would represent an important property for specific adsorption.
Ammonia Volatilization from Surface Applications of Ammonium Compounds on Calcareous Soils: IV. Effect of Calcium Carbonate Content
Authors: Fenn L. B. , Kissel D. E. 
Published: July 2010

AbstractThe purpose of this study was to determine the effect of soil CaCO3 content on ammonia volatilization from surface applied ammonium compounds. Ammonia‐nitrogen losses from surface‐applied (NH4)2SO4 increased rapidly to 6.1% soil CaCO3, with slight NH3 loss increases from 6.1 to 9.7% soil CaCO3, and no NH3 loss increase beyond 9.7% soil CaCO3. Ammonium nitrate reached maximum NH3‐N loss at 1.3% soil CaCO3 and 110 kg NH4+‐N/ha, with lower but still increasing losses of NH3‐N at 6.1% soil CaCO3 and 550 kg NH4+‐N/ha.The acidity of the ammonium compounds caused a reduction in final soil pH at low CaCO3 levels and high NH4+‐N application rates; but at 6.1% soil CaCO3 and above, the pH values remained at 7.5 to 7.6. The effect of soil pH on NH3‐N losses was greater for NH4NO3 than for (NH4)2SO4. For (NH4)2SO4, the percent loss of NH3‐N below 1.3% soil CaCO3 decreased as NH4+‐N application rates increased; but at 2.9% and above, NH3‐N losses were greatest at the highest rate of NH4+‐N application. In contrast, no reversal in NH3‐N losses were observed for NH4NO3 with increasing soil CaCO3 content and NH4+‐N application rates.Multiple regression analysis of NH3‐N losses with respect to time, temperature, rate of NH4+‐N application, and soil CaCO3 content resulted in two equations with correlation coefficients (R2) of 0.88 and 0.85.
Nitrogen Fixation by Algae in Fescuegrass Soil Crusts
Authors: Reddy Gudiogopuram B. , Giddens Joel 
Published: July 2010

AbstractSoil crusts and subsoil samples of different ages of tall fescuegrass (Festuca arundinacea Schreb.) were collected and analyzed for N, C, and acetylene reduction. Total N and C in the crust was 0.18% and 2.76%, respectively, in 4‐year old soil crust as compared to 0.06% and 0.67%, respectively, in fallow soil. The amount of acetylene reduction after 5 days' incubation was 13.77 µmole/flask (9.6 cm2) for the 4‐year‐old sod crust compared to 3.06 µmole/flask for the fallow control. Ammonium nitrate reduced and liming increased N fixation in the crust. Nitrogen fixation in the crust was highest at 55% shade. Blue‐green algae present in the crust were Anabaena, Nostoc, Syctonema, and Oscillatoria. Greater nitrogen fixation occurred when moss (Bryum sp.) was present in crust.
Vehicle Perturbation Effects upon a Tundra Soil‐Plant System: II. Effects on the Chemical Regime
Authors: Challinor J. L. , Gersper P. L. 
Published: July 2010

AbstractChemical regime alterations of a soil‐plant system resulting from tracked‐vehicle perturbation were determined in Tundra soils near Barrow, Alaska. The study was a contribution to the USIBP Tundra Biome Program.Six years following the perturbation, soils within track scars had lower redox potentials (negative) and lower amounts of exchangeable acidity than undisturbed soils. Furthermore, exchangeable bases (Ca, Mg, K and Na) were higher in the track influenced soils. Consequently, soil pH and base saturation were also higher.Soluble nutrient (Ca, Mg, K, Na, and NH4‐N) levels in soil solutions were considerably higher in track‐influenced soils than in undisturbed soils. Correspondingly, soil solution pH was also higher.Plants growing in the altered environment of the track scars were enriched in nutrients and were larger in size. Increased productivity and quality of track‐influenced vegetation was apparently stimulated by an increase in available nutrients in less acid, warmer, nutrient enriched soils. The track perturbation also resulted in changes in floristic composition of the vegetation at different locations within track‐affected soils.The intensity of soil alteration and resulting changes in the soil‐plant chemical regime were related to the degree of scarring of the landscape which, in turn, was related to differences in the natural drainage of soils along the tracks; scarring being greater, the poorer the natural drainage.Results show that a slight amount of disturbance to the tundra surface may be beneficial in terms of increased productivity and nutrient content of vegetation.
Soybean and Corn Rooting in Southwestern Minnesota: I. Water‐Uptake Sink
Authors: Allmaras R. R. , Nelson W. W. , Voorhees W. B. 
Published: July 2010

AbstractSink terms in the transient soil water flow equation were estimated to provide accurate descriptions of field water uptake. Water uptakes by vertically developing root systems of three crops were described as a function of time during drying of a Nicollet soil which often has a perched water table at 1.3 to 2 m early in the growing season. During the period 1 July through 15 Aug., water uptake by corn (Zea mays L.) was compared with that by determinate and indeterminate isolines of ‘Harosoy’ soybean (Glycine max. L. Merr.). These accounts of water uptake were later compared with directly examined rooting patterns.Water depletion measurements (with neutron probe) underestimated transpiration beginning in late July when upward water flows at 140 cm were 0.4 to 0.6 of transpiration. Depletions by soybeans occurred at shallower depths than corn. The indeterminate isoline showed greater depletions than the determinate isoline at shallow depths.Water flows in the rooting zone were estimated from tensiometric measured hydraulic gradients and hydraulic conductivity, calculated to match in situ field estimates. Peak flows to the root system progressed with time from the shallow to deeper depths. Maximum flows at the 122‐ to 152‐cm depth ranged from −0.6 for soybeans to −0.8 cm/day for corn. Soil water potentials at maximum flow were −180 to −600 mbars with lower potentials noted for soybeans.Sinks for soybean water uptake showed greater and earlier water extraction at shallower depths than corn. Sinks for water uptake by all three crops moved down with time until 30 July, when water extraction by soybeans became limited by depth of rooting. Pan evaporation increased significantly, and the corn root sink continued to move down.Integrals of the sink term early in the period overestimated by 20% the sum of depletion and upward movement into the rooting depth. Later in the test period sink term integrals underestimated the same sum by 25%.
Fluometuron and Water Content Distributions During Infiltration: Measured and Calculated
Authors: Wood A. L. , Davidson J. M. 
Published: July 2010

AbstractLaboratory columns of Cobb sand were used to study the movement and distribution of surface applied 1,1‐dimethyl‐3‐(α, α, α,‐trifluoro‐m‐tolyl) urea (fluometuron) for three infiltration rates and two initial soil‐water contents. Fluometuron movement showed little dependence on initial soil‐water content for a given infiltration rate. Experimental data indicated that equilibrium existed between the adsorbed and solution phases for all infiltration rates and initial soil water contents studied with the exception of the ponded infiltration into air‐dry soil case. A simultaneous numerical solution of the water and solute transport equations described a fluometuron pulse, for large infiltration rates, which lagged the experimental data. The agreement between calculated and measured distributions was improved when the infiltration rate was reduced. The shape of the fluometuron pulse was reasonably well described by the mathematical model.
Phosphate Adsorption by Soils: II. Reactions in Tropical Acid Soils
Authors: Rājan S. S. S. , Fox R. L. 
Published: July 2010

AbstractPhosphate adsorption by several Hawaiian and Indian soils, and the relation of phosphate adsorption to hydroxyl, sulfate, and silicate ions released in two Hawaiian soils were studied. Adsorption isotherms of some of the soils show an abrupt increase in phosphate adsorption at high concentrations.The isotherms were analyzed applying a binary Langmuir equation (assuming two types of sites). The curve predicted by the Langmuir parameters describes the portion of the isotherm where adsorption seems to be mainly by surface ligand exchange (at low levels of phosphate adsorbed). Where additional reactions occur the experimental points deviate from the predicted curve.Phosphate adsorption is associated with increased pH and sulfate release at low levels of phosphate adsorbed and increased silicate release throughout. The observations suggest that at low concentrations phosphate exchanges with (i) adsorbed sulfate and adsorbed silicate, and (ii) with water and hydroxyls of metal hydrous oxides and edge aluminum of clays. At high concentrations additional phosphate is adsorbed by displacing the structural silicate of clays. The increase in phosphate adsorption by structural silicate release, over that of surface exchange reactions, is about 50 and 25% in two soils containing kaolinite and allophane clays respectively.
Determination of Arsenate, Methanearsonate, and Dimethylarsinate in Water and Sediment Extracts
Authors: Yamamoto M. 
Published: July 2010

AbstractA method is described for separating and measuring arsenate, methanearsonate, and dimethylarsinate in water and sediment extracts. The arsenicals were separated by differential elution from a column of cation exchange resin; and the separates were subsequently analyzed by the arsine method. Standard arsenical solutions separated well, and 97, 93, and 95% of arsenate, methanearsonate, and dimethylarsinate, respectively, were recovered in the effluents. The method was tested with pond sediments previously treated in the laboratory with known levels of arsenicals. Recovery varied from 80 to 98%.
Effect of Temperature on Denitrification Rate in Soils
Authors: Stanford George , Dzienia Stanislaw , Vander Pol Roger A. 
Published: July 2010

AbstractThe effect of temperature on denitrification rate was studied with nine soils differing widely in organic matter content and chemical and physical characteristics. In the range of 15 to 35C, the temperature coefficient of denitrification, Q10, was approximately 2. Denitrification rates at 35 and 45C were similar. Between 10 and 5C, denitrification rate declined abruptly. The lower limit of the temperature range conforming to a Q10 of 2 was estimated to be 11C. In this study of water‐logged soils sealed from the atmosphere, denitrification appeared to obey first‐order kinetics.
Effects of Parent Material on Genesis of Borolls and Boralfs in South‐Central New Mexico Mountains
Authors: Anderson J. U. , Bailey O. F. , Rai Dhanpat 
Published: July 2010

AbstractA field study of a 186 km2 area, a more detailed study of a 65 ha area, and laboratory analysis of four soil profiles has shown that, in this high elevation forested area in New Mexico, Borolls are forming in residuum from limestone, but Boralfs are forming where the parent material is from sandstone. These Borolls resemble the classic concept of Rendzina, but lack a udic moisture regime necessary for Rendolls. The Boralfs are distinctly different from the Borolls even though all soil‐forming factors other than parent material appear to be the same. The absence of evidence of illuviation of clay in the Borolls can probably be attributed to the presence of calcium carbonate in all soil horizons, but the very great differences in organic matter content can probably not be accounted for by the data presented.
Distribution and Properties of Some Tidal Marsh Soils of Apalachee Bay, Florida
Authors: Coultas C. L. , Gross E. R. 
Published: July 2010

AbstractTidal marshland forms a border between the Apalachee Bay area of the Gulf of Mexico and the uplands of Taylor County, Florida. The purpose of this investigation was to determine the distribution of the tidal marsh soils and to measure some of the properties used in their classification. Three pedons representative of the major soils were described and sampled. The range of electrical conductivity is from 14 to 90 mmhos/cm. Field moist pH ranges from 5.6 to 7.8 and air dried pH values are 2 to 3 pH units lower. Content of S is < 0.75% in the Psammaquents and Haplaquods to 6.8% in the Sulfaquents. Oxidation of S to sulfates was probably responsible for the increase of soil acidity after drying. Cation exchange capacity ranges from 2 to 25 meq/100g for the Psammaquents and Haplaquods and from 25 to 75 meq/100 g for the Sulfaquents. Most soils are nearly base saturated. The soils classified in order of increasing elevation are members of the coarse‐loamy, mixed, thermic Typic Sulfaquents; the sandy, siliceous, thermic Mollic Psammaquents; and the sandy, siliceous, thermic Aeric Haplaquods. Because of high potential acidity, low bearing strength, and high salinity, decisions concerning man's use of tidal marsh soils should be carefully made. Undisturbed, these are productive soils performing functions valuable to man.
Genesis of Argillic Horizons in Soils of Desert Areas of the Southwestern United States
Authors: Nettleton W. D. , Witty J. E. , Nelson R. E. , Hawley J. W. 
Published: July 2010

AbstractWe studied soils and landscapes in the southwestern part of the Lake Lahontan drainage basin in Nevada and soils on alluvial fans near Phoenix and Willcox, Arizona and Mojave, California. The youngest surface is less than 12,000 YBP (years before present), the oldest is pre‐Wisconsin in age. Typic Torripsamments are on surfaces younger than 12,000 YBP, finer textured Haplargids and Paleargids are on surfaces older than 12,000 YBP. The volume of clay skins in a sandy family of Xeralfic Haplargids on a late Wisconsin age, dune‐sand surface is approximately equal to the increase of clay in its B horizon, whereas clay skins are mostly lacking in the fine‐textured Haplargids and Paleargids formed in sandy alluvium. Both the distribution of quartz and total silica in the sand + silt and the distribution of volcanic fragments in the very fine sand show that the A horizons of the finer textured Haplargids and the Paleargid are as weathered as, or more weathered, than their B horizons. This is evidence that the B horizons of Argids were formed at least in part by translocation of clay. Accumulation of total Al2O3 and Fe2O3 in these argillic horizons is more direct evidence that clay translocation occurred. The older Argids have clay maxima below the calculated depth of wetting in most years. These clay maxima are near the depth of wetting expected once or twice each 100 years in the older Argids, but the present climate does not seem adequate to have produced the soils in the time involved. Rather these older Argids are probably products of moister Plestocene climates.