bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dissolution and Stability of Biogenic Opal
Authors: Wilding L. P. , Hallmark C. T. , Smeck N. E. 
Published: July 2010

AbstractBiogenic opal isolated from leaves of seven deciduous trees, one grass species, and surface horizons of forest and grassland soils, was examined for dissolution in hot and cold distilled water. In cold water, silica dissolution was torpid and Si concentrations remained nearly constant through a 4‐week equilibration period; Si values for all but one opal specimen were between < 0.5 and 2 µg Si/ml. Dissolution over a 5‐hour period in distilled water at 90°C yielded the following Si concentrations (µg Si/ml): 4 to 5 for tree‐leaf isolates; 1 to 8 for soil isolates, 83 for the grass isolate, 0.5 for quartz, and 110 for silica gel. Opal dissolution is greater for 2–5 µm soil isolates than 5–20 µm isolates. Biogenic opal isolated from soils and deciduous tree leaves is much more stable than previously considered and exhibited Si dissolution similar to that reported for geologic opal. Further work is needed to clarify differences in opal solubilities between grass and forest origin.
Soil Nitrification Retardation by Rice Pesticides
Authors: Turner Fred T. 
Published: July 2010

AbstractThe effectiveness of selected rice pesticides carbofuran, molinate, propanil, bifenox, and sodium azide in comparison to nitrapyrin and terrazole in retarding soil nitrification was evaluated by determining increases in nitrate‐N concentrations and/or decreases in ammonium‐nitrogen concentrations. In a vertisol to which 50 ppm ammoium‐N had been added and pesticide applied at recommended application rates, all compounds showed evidence of nitrification inhibition during the first 10 days of incubation. After 60 days incubation, only bifenox, sodium azide, terrazole, and nitrapyrin were still retarding nitrification. Similarly in another experiment the pesticides, applied at one‐half to 10 times the recommended application rate, were not as effective as nitrapyrin and terrazole in retarding nitrification in a moist alfisol and vertisol; yet, each pesticide exhibited some nitrification inhibition, especially at the excessive application rate. The effectiveness of the individual pesticides in retarding nitrification varied with soil type. These rice pesticides have potential to retard nitrification that should be recognized when studying N transformations in soils or when studying the effect of pesticides on plants grown in soil.
Measurement and Numerical Simulation of Hysteretic Flow in a Heterogeneous Porous Medium
Authors: Gillham R. W. , Klute A. , Heermann D. F. 
Published: July 2010

AbstractA finite difference solution of the Richards equation was tested experimentally for hysteretic flow in a nonuniform medium. The space‐dependent hydraulic properties (water content‐pressure head and hydraulic conductivity‐water content) were determined experimentally on a laboratory column of sand and were represented in the numerical model by empirical equations.Boundary conditions resulting in hysteretic flow were applied to both the experimental column and the numerical model and the resulting water content and pressure head profiles were compared. Agreement was excellent between the measured and computed results. An additional simulation, in which the medium was considered to be nonhysteretic, gave good agreement between the measured and computed pressure head values but resulted in substantial error in the computed water content values.
Onion Response to Lime on Acid Histosols as Affected by Ca/Mg Ratios
Authors: van Lierop W. , Martel Y. A. , Cescas M. P. 
Published: July 2010

AbstractThe objectives of this work were to determine critical ratios and concentrations of Ca and Mg in Histosols as related to onion (Allium cepa L.) growth and composition.The molar Ca/Mg ratios extracted from soils were related to those found in onion and indicated that onion assimilated Mg more easily than Ca. Although the upper critical Ca/Mg ratio was not found, yields decreased rapidly as extracted soil and tissue Ca/Mg ratios became smaller than the lower critical ratio of 0.5. Onion yields, however, were not related to the soil extracted Ca/Mg ratio interval from 0.5 to at least 16, and a corresponding tissue range of 0.5 to 6.5.Maximum yields were obtained when tissue concentrations of Ca+Mg ranged between 90 and 110 meq/100 g. These yields were obtained when soils released about 25–28 meq of Ca + Mg/100 g as extracted with a modified double acid procedure (0.05N HCl + 0.025N H2SO4). Concentrations higher than 16–18 meq Mg/100 g extracted from soils and 58–71 meq Mg/100 g in plants (depending on the concentration of Ca + Mg extracted from soils and absorbed by plants) exceed the upper critical limit and cause Mg‐induced Ca deficiencies and reduced yields.The lower critical concentration points for Mg, and conversely the higher critical concentration limit for Ca, was not identified. However, yields were not affected when soils released as little as 1.5 meq Mg/100 g and plants absorbed only 14 meq Mg/100 g if sufficient Ca was available to produce maximum yields. These data emphasize the importance of maintaining the Ca/Mg ratio in the proper range when liming acid histosols for vegetable production.
Properties and Geomorphic Relationships of Some Soils of Liberia
Authors: Geiger Luther , Nettleton W. D. 
Published: July 2010

AbstractLiberia is on the west coast of Africa near the Equator. It is in a tropical rain forest in an area of shifting cultivation. The five soils studied are on rolling uplands, stream terraces, and swampy bottomlands. Their properties reflect their geomorphic ages.Plinthic Paleudults of the clayey‐skeletal family are on the highest uplands. Compared to the other Paleudults, they are more clayey, and have higher amounts of extractable iron, and contain high amounts of ironstone concretions (hardened plinthite). The argillic horizons have 0.3 meq of Ca2+ and Mg2+ or less per 100 g of soil. Because of the gravel, these soils are best suited to rubber (Hevea brasiliensis) or cashews (Anacardium occidentale L.).The loamy family of Plinthic Paleudults and the clayey family of Typic Paleudults occupy lower erosional uplands. They are similar to the higher, clayey‐skeletal Paleudults but are slightly higher in bases in the lower horizons. Both are well suited to production of oil palm (Elaeis guineesis Jacq.), coffee (Coffea spp.), rubber, and cashews.The Typic Tropopsamments and Aquoxic Dystropepts of the clayey family occupy low stream terraces. Both soils have more weatherable minerals and a more favorable base status than the Paleudults. The Dystropepts are best suited to oil palm production. The Tropopsamments are well suited to cacao (Theobroma cacao L. subsp. cacao) coffee, oil palm, and rubber.The Paleudults studied have the chemical properties of the Oxisols. They have a much lower CEC (cation exchange capacity) per unit of clay, and lower base saturation than apparently is intended for Ultisols. We propose that a new subgroup, Aquoxic Paleudults, be provided for these soils.
Influence of Twin‐Row Spacing and Nitrogen Rates on High‐Frequency Trickle‐Irrigated Sweet Corn
Authors: Phene C. J. , Beale O. W. 
Published: July 2010

AbstractSweet corn (Zea mays L.) is generally grown in rows spaced about 100 cm apart. Trickle irrigating this type of row configuration is inefficient and costly because one irrigation tube must be installed on each row. The objectives of this research were to determine the influence of trickle irrigation; wide bed, “twin‐row” spacing; and trickle N and K fertilization rates on the yield and quality of sweet corn. The twin rows, 35 cm apart, were positioned on wide beds, spaced 165 cm from center to center. A single trickle irrigation tube was placed between the twin rows of corn, providing water and nutrients simultaneously to both rows. Sweet corn was fertilized daily with seasonal applications of 28, 56, 168, and 336 kg/ha of N and K. Plant height, ear yield, and biomass production increased with N and K rates ranging from 0 to 168 kg/ha, but were not affected by the twin‐row bed spacing nor by fertilizing with 336 kg/ha each of N and K.
A Rainfall Simulator with Nonrepetitious Movement of Drop Outlets
Authors: Kleijn W. B. , Oster J. D. , Cook N. 
Published: July 2010

AbstractProblems encountered in simulating uniform rainfall inside the laboratory are discussed. A new rain simulator is described which eliminates nonuniformity by a nonrepeating movement of drop outlets. The model tested applies rain to a ring‐shaped area of 0.21 m2 with a coefficient of variation of about 7%. By using drop outlets of different sizes, one also can adjust the raindrop size distribution.
Simultaneous Transport of Surface‐Applied Salts and Water Through Unsaturated Soils as Affected by Infiltration, Redistribution, and Evaporation
Authors: Dahiya I. S. , Singh Mohinder , Singh Mahendra , Hajrasuliha S. 
Published: July 2010

AbstractA study, conducted in soil columns and involving three texturally different initially moist and dry soils, verifies certain concepts regarding simultaneous transport of surface‐applied salts and water under transient unsaturated flow conditions. Calcium chloride, spread on the soil surface, was leached with water under transient and steady infiltration conditions. Salt and water profiles were determined immediately following infiltration and after matching total infiltration, redistribution, and evaporation times.Chloride was leached more efficiently and to relatively deeper depths with lower than with higher rates of water application only in sandy and sandy loam soils. Appreciable chloride accumulation occurred during evaporation in surface layers of these soils in columns initially leached with continuous ponding of water. Irrespective of water application rates, nearly no upward movement of salts occurred in clay soil due to evaporation. In all cases, the displacement of salts by invading salt‐free water did not show piston‐like behavior as reported by some workers. In contrast to some earlier reports, the advance of the salt front was dependent on the initial soil water content. Upward movement of salts toward surface layers due to evaporation was greater in initially moist sandy loam and initially dry sandy soils.
Extractable Iron and Manganese as Related to Soil pH and Applied Chromium
Authors: Grove J. H. , Ellis B. G. 
Published: July 2010

AbstractMetal‐metal interactions in soils can be very important in determining the composition and yield of plants. Chromium application has been shown to affect plant Mn concentrations and uptake, and Fe deficiency symptoms have been associated with Cr toxicity by some workers.The objectives of this study were to evaluate the changes in soil Mn and Fe resulting from added Cr(III), Cr(VI), and a high Cr content sludge. Treatments of 0 and 500 ppm Cr as CrCl3 and CrO3 and sludge Cr at a rate of 1,400 ppm Cr were applied to Rubicon sand, a sandy, mixed, frigid Entic Haplorthod (pH 4.7); Morley clay loam, a fine, illitic, mesic Typic Hapludalf (pH 6.0); and limed Morley clay loam (pH 7.5). Pots were sampled after 24 hours, 1, 2, 4, 8, and 16 weeks of incubation. Soil samples were extracted in succession with deionized‐distilled water, 1M NH4Cl, 0.1M CuSO4, 0.3M (NH4)2C2O4, and citrate‐dithionite‐bicarbonate.Water‐soluble Fe was reduced on all soils by Cr(III) and sludge amendment. Sludge amendment increased oxalate‐soluble Fe. Chromium (VI) initially lowered water‐soluble Fe, later raising this fraction above control soil levels.Water‐soluble Mn increased as incubation time increased on all soils treated with water soluble Cr(III). Chromium (VI) initially raised water‐soluble Mn, later lowering this fraction to levels not significantly different from control pots. Sludge‐amended soils produced more water‐soluble Mn with longer incubation times.Addition of inorganic Cr compounds to soils induced changes in soil pH subsequently affecting the soil chemistry of Mn. A Cr‐Fe coprecipitation reaction was indicated by the data.
The Toxicity of Banded Urea or Diammonium Phosphate to Corn as Influenced by Soil Temperature, Moisture, and pH
Authors: Creamer F. L. , Fox R. H. 
Published: July 2010

AbstractA laboratory and greenhouse study, using a Hagerstown silt loam (Typic Hapludalf, fine, mixed, mesic) was designed to determine the effect of initial soil pH, soil temperature, and soil moisture on NH4+ + NH3‐N movement and concentration, pH change, and NO2‐‐N production and accumulation around urea or diammonium phosphate (DAP) banded at 80 or 100 kg N/ha (assuming 76 cm between bands). Observations were also made in the greenhouse on corn root growth around banded urea plus triple superphosphate (TSP), NH4NO3 plus DAP, urea plus DAP, urea plus DAP with 100 kg Mg/ha, and urea plus DAP with a nitrification inhibitor (nitrapyrin). Root growth around those treatments was compared to banded NH4NO3 plus TSP and no‐starter controls. Nitrogen and phosphorus were applied at 100 kg/ha and 60 kg/ha in the band, respectively.Increasing the initial soil pH and decreasing soil moisture increased the proportion of total NH4+ + NH3‐N present as free NH3 around banded urea or DAP. Lowering soil temperature appeared to inhibit nitrification and help maintain high pH and NH4+ + NH3‐N concentrations for a longer time.With both urea and DAP, NH3 toxicity appeared to be the main cause for root growth inhibition around the band. Magnesium did not decrease toxicity symptoms nor did NO2‐ accumulate to toxic levels. Ammonia toxicity potential from DAP was lower than an equivalent amount of urea due to the smaller pH increase adjacent to the band of DAP. At a banded rate of 100 kg N/ha, urea increased the pH in Hagerstown silt loam from 6.8 to 9.1 whereas DAP increased pH to only 7.3.
Cotton Yield and Nutrient Uptake in Relation to Water Table Depth
Authors: Meek B. D. , Owen‐Bartlett E. C. , Stolzy L. H. , Labanauskas C. K. 
Published: July 2010

AbstractA field experiment was conducted to evaluate the effect of three water‐table depths (30, 60, and 90 cm) on growth of cotton (Gossypium hirsutum L. var. ‘;Stoneville 213’). Soil aeration, plant water relations, cotton seed yield, and nutrient uptake were measured. The depth of the water table was controlled by adding water to subsurface drains.The optimum water‐table depth was 90 cm or greater with reductions in seed cotton yield of 43 and 25% for water‐table depths of 30 and 60 cm, respectively. As the water‐table depth increased from 30 to 90 cm, concentrations in stems and leaves of N, Ca, K, and Cu increased whereas concentrations of P, Mg, Na, B, and Cl decreased. Increasing the water‐table depth increased the total uptake of all elements studied.When the water‐table depth was increased from 30 to 90 cm, the soil aeration status increased considerably as measured by soil oxygen content, redox potential, and oxygen diffusion rate.
Zinc, Cadmium and Manganese Uptake by Soybean from Two Zinc‐ and Cadmium‐Amended Coastal Plain Soils
Authors: White M. C. , Chaney R. L. 
Published: July 2010

AbstractTwo Coastal Plain soils were used to evaluate the effects of organic matter and Fe and Mn hydrous oxides on Zn phytotoxicity, and on Zn, Cd, and Mn uptake by soybean seedlings. Fertilized Pocomoke sl and Sassafras sl were limed to pH 5.5 and 6.3 with CaCO3 when adding Zn (six levels between 1.3 and 196 mg/kg at pH 5.5; seven levels between 1.3 and 524 mg/kg at pH 6.3). Cadmium was added at 1% of the added Zn. ‘Beeson’ soybean (Glycine max L. Merr.) was grown 4 weeks, and the trifoliolate leaves evaluated for dry weight yield and for their Zn, Cd, and Mn concentrations.The higher organic matter Pocomoke soil was more effective than the Sassafras soil in reducing metal uptake and Zn phytotoxicity. Foliar Zn levels associated with yield reduction of soybean grown on Pocomoke differed with soil pH. Cadmium uptake was significantly lower on the Pocomoke soil. Foliar Mn increased to reported phytotoxic levels (>500 mg/kg) with increased added Zn only on the Sassafras soil at pH 6.3.DTPA‐extractable Zn and Cd were linear functions of added Zn and Cd for both soils; 0.01M CaCl2‐extractable Zn and Cd were curvilinear (increasing slope) functions for the Sassafras and linear for the Pocomoke soil.Thus, soil type can strongly influence Zn, Cd, and Mn uptake, as well as Zn phytotoxicity to soybean. Soil organic matter appears to be more important than hydrous oxides of Fe and Mn in moderating the effects of excessive soil Zn and limiting Zn and Cd uptake. Induced metal toxicities (Mn) may depend on many factors, and should be considered an integral part of any characterization of specific metal phytotoxicities (e.g. Zn).
Soil Development on Moraines of Taylor Glacier, Lower Taylor Valley, Antarctica
Authors: Pastor J. , Bockheim J. G. 
Published: July 2010

AbstractSoils were examined on moraines deposited by Taylor Glacier in lower Taylor Valley to determine changes in soil properties with time in an environment of extreme cold and aridity and minimal biologic activity. The soils range in age from 200,000 to 2.7‐3.5 million years BP. Soil profiles contain a desert pavement over a weakly expressed B horizon, followed by permafrost, which may be “dry” or ice‐cemented. The soils are alkaline (pH 7.5 to 9.0) and are enriched in salts. Based on X‐ray diffraction, the salts are mirabilite (Na2SO4·10H2O), tachyhydrite (CaMg2Cl6·12H20), and halite (NaCl). Electrical conductivity of the salt‐enriched zone ranges from 2.8 to 9 mmho cm−1. Sodium and chloride are the dominant ions in 1.5 soil/water extracts. Ion ratios suggest that the bulk of the salts are of marine aerosol origin. The soils are generally gravelly sands, but the amounts of clay (<2 µm) and medium+fine silt (2–20 µm) increase with soil age. Free iron also increases with age. Secondary clay minerals include montmorillonite, vermiculite, and interstratified layer silicates. The predominant clay mineral weathering process is hydration of mica. The age‐soil property relationship may have been influenced by microclimatic variations, previous occurrence of lakes dammed by a westward flowing marine ice sheet, mass‐wasting processes, and persistent ice‐cemented frost table in the solum. The soils are classified as Pergelic Cryorthents, sandy‐skeletal, mixed, frigid.
A Model to Predict Tillage Effects on Soil Temperature
Authors: Cruse R. M. , Linden D. R. , Radke J. K. , Larson W. E. , Larntz K. 
Published: July 2010

AbstractA simulation model was developed to predict tillage effects on average daily soil temperature at the 5‐cm depth. A two‐step procedure was utilized: (i) an average daily soil temperature was predicted on a flat, bare, undisturbed soil; and (ii) the temperature from step 1 was modified due to tillage‐induced changes in solar radiation absorption and soil thermal inertia. Soil and residue properties required for the model were: soil water content at the wilting point, soil bulk density, soil random roughness, initial residue dry weight, residue reflection coefficient at model initiation, soil reflection coefficient, and percentage of quartz, clay, and organic matter. Daily soil and climatic inputs required were: maximum and minimum air temperature, incoming solar radiation, wind travel, soil water content at the 5‐cm depth, and stage of evaporation. Results indicated this approach may have significant potential when soil heat flow is predominantly by conduction.
Phosphorus Response of Western Hemlock Seedlings on Pacific Coastal Soils from Washington
Authors: Heilman Paul E. , Ekuan Gorden 
Published: July 2010

AbstractThis study showed that poor growth in the greenhouse of western hemlock seedlings (Tsuga heterophylla Raf. Sarg.) on two pedons from Pacific coastal hemlock forests in Washington is, due primarily to deficiency of P. Without P treatment, seedlings on three horizons of two pedons of the Vesta series contained from 0.03 to 0.09% P in their foliage. Addition of P at the rate of 300 kg P/ha raised the foliar P level to 0.09 to 0.18%. Mean seedling height at 9 months on soil with P added was 184% and dry weight was 233% of the corresponding values without P. Addition of forest floor material to the pots at a 1:2 (volume) ratio to soil increased seedling growth and concentration of P in foliage and reduced the growth response to P treatment. Phosphorus treatment reduced foliar N levels whereas the effect of forest floor on foliar N was inconclusive.Soil P data from analysis of 38 coastal hemlock pedons showed that pedon samples used in the greenhouse study were average to below average for the area in status of P.
Plot Size Requirements for Measuring Residual Fertilizer Nitrogen and Nitrogen Uptake by Corn
Authors: Olson R. V. 
Published: July 2010

AbstractAn experiment was conducted to ascertain the minimum size of unconfined plot that can be used to measure accurately residual fertilizer N and to measure N taken up by corn (Zea mays L.) from broadcast N fertilizer. Large plots were fertilized with 15N‐enriched (NH4)2SO4 and plant samples were taken from different places within plots. Samples of grain and stover taken 36 cm from two edges of the plots contained significantly less N derived from fertilizer than plants 107 or 154 to 202 cm from edges.Accurate values for plant uptake of fertilizer N could be obtained by sampling the center plant of 3‐row plots at least 214 cm long and 71 cm apart. Plots should be larger if several plants are to be sampled. It appears larger plots are needed also to determine residual fertilizer N in the soil.
Properties and History of an Exhumed Tertiary Oxisol in California
Authors: Singer Michael J. , Nkedi‐Kizza Peter 
Published: July 2010

AbstractThe Ione Formation occurs as isolated exposures along the western foothills of the Sierra Nevada. Presence of an intensely weathered soil profile (an Oxisol) on remnants of the Eocene Ione Formation is direct pedologic evidence for a tropical climate during or subsequent to that time. This is the first detailed description of an exhumed Oxisol in the continental United States. The pedon described here has a thin Al horizon, a red and yellow ironstone horizon over a thick oxic horizon. Below the oxic horizon is a thick deposit of kaolinite clay. The oxic horizon has 11.4% F2O3, 0.04% organic C, 10.9 meq/100 g clay CEC (Cation Exchange Capacity), 3.5 meq/100 g clay KCl extractable Al, and a pH in H2O of 3.3. Kaolinite is the only clay mineral present. This relict soil pedon does not meet criteria below the order level in Soil Taxonomy because of moisture regime limitations. Data such as these illustrate the usefulness of pedology in the study of Tertiary paleoclimatology.
Derivation of the Freundlich Equation for Ion Exchange Reactions in Soils
Authors: Sposito Garrison 
Published: July 2010

AbstractThe Freundlich adsorption isotherm equation is derived rigorously for the trace adsorption of an ion participating in an exchange reaction. The derivation, which is an application of some general results obtained by R. Sips, is based on the assumption that the exchanger surface is heterogeneous and that each class of exchange sites adsorbs individually accordingly to the Langmuir isotherm. It is shown that, under these conditions, the Freundlich isotherm corresponds uniquely to a distribution of relative adsorption site affinities which is essentially log normal and that the empirical parameters in the Freundlich equation may be used to characterize the site distribution function mathematically, thus giving information about surface heterogeneity in the exchanger.