bluuebunny/crossref_metadata_2025 huggingface dataset:
Seasonal Weather Regimes Influence Interpretation of Pinus resinosa Foliar Analysis
Authors: Bickelhaupt Donald H. , Lea Russell , Tarbet Don D. , Leaf Albert L.
Published: July 2010

A technique is described for quantifying the influence of seasonal precipitation and atmospheric temperature patterns (using degree‐day summations) on annual foliar analysis data. The results of this are used to adjust for the influence of climatic variation on foliar data so as to obtain a better estimate of species and soils relations. For Pinus resinosa, a species with determinate growth characteristics, precipitation and degree‐day summations over a portion of the previous snow‐free season plus the same measures for the current snow‐free season may be used to adjust annual foliar analysis data to improve these data for diagnostic purposes.
Solute Dispersion in Unsaturated Heterogeneous Soil at Field Scale: II. Applications
Authors: Bresler Eshel , Dagan Gedeon
Published: July 2010

The model for nonadsorbed solute spread by vertical steady‐state flow of water in a heterogeneous field soil, developed in Part 1, is applied to a Panoche soil with properties which have been investigated previously. Average solute concentration profiles as functions of depth and time are computed for various surface rates of infiltration. The average concentration over a layer extending from the soil surface to a given depth is also computed. It is shown that the concentration profile extends over an apparent mixing zone which is much larger than that predicted by a conventional diffusion‐convection (dispersion) equation in a homogeneous fictitious field, and that the latter lacks practical significance for prediction of solute spread in the field. The implications of the results for the leaching of saline field soil and crop yield estimates as they are influenced by rate of surface recharge and its uniformity are also discussed.
Cation Release from Michigan Spodosols Leached with Aspen Leaf Extracts
Authors: Adams Paul W. , Boyle James R.
Published: July 2010

Soil samples (<2 mm) from the A horizons of three sandy Michigan Spodosols of varying productivity were leached with water extracts of Populus grandidentata Michx. leaves. Laboratory leaching experiments were used to simulate natural weathering of soil minerals by hydrogen ions of organic acids and the complexing of cations by organic compounds in the extracts. All of the soil samples released significant amounts of Mg, K, Na, and Fe, and most released Ca. Using data for Fe released by the leachings and existing data for subsoil Fe accumulation and ground water losses in similar soils, an estimate was made of the number of years of field conditions simulated by the laboratory treatments. The annual elemental release through mineral weathering in the A horizon in each soil was then estimated. Although estimated Ca weathering rates were notably low, estimated rates of Na weathering were comparable to those observed for podzol soils in New England.
A Comparison of Solid and Liquid Fertilizer for Coastal Bermudagrass Hay Production
Authors: Walker M. E. , Keisling T. C. , Marchant W. H.
Published: July 2010

Coastal bermudagrass (Cynodon dactylon L. Pers.) response to N, P, and K fertilization has been well documented. Generally, the accepted result of previous work is a fertilization program consisting of either (i) applying a 10‐1‐4 N‐P‐K ratio or (ii) fertilizing to increase the acid extractable P and K to 25 and 50 to 70 mg/kg, respectively. Under (ii) N is applied as needed to obtain the desired forage production and protein concentration. Liquid urea‐nitrogen solutions have been investigated but little information on liquid P and K is available. An experiment with the objective of comparing liquid N, P, and K to conventional soild fertilization practices on Coastal bermudagrass was conducted on a Tifton soil (Plinthitic Paleudult; fine, loamy, siliceous, thermic) using a well established sod. A split plot design was used. Main plots were physical fertilizer form. Subplots were a complete 3 × 5 factorial with annual applications of 0, 37, and 74 kg/ha P and 0, 93, 186, 279, and 372 kg/ha K. Nitrogen was applied at 336 kg/ha for both liquid and solid forms. All fertilizer was applied each season as four equal split applications. Soil samples were analyzed for P, K, Ca, and Mg and soil pH was measured. Liquid fertilizer containing N, P, and K produced essentially the same forage digestibility as conventional solid fertilizer. Forage yield and N recovery was less with the liquid N source compared to solid fertilizer containing ammonium nitrate. The percentage digestible dry matter decreased as the % K in the forage decreased below approximately 1.5%. At the lower tissue K concentrations, the sod was infested to various degrees by Texas panicum (Panicum taxanum Buckl.), ragweed (Ambrosia artemisfolia L.), and large crabgrass (Digitaria sanguinalis L. Scop.) whose contribution to the forage yield would cause a reduction in digestibility. At 336 kg/ha N, more K was removed in the forage than was added when previously proposed N‐P‐K ratios were used. This excess removal of K by the forage could result in nutritional imbalances when soil reserves are exhausted. Applying high rates of K did not cause K accumulation in the Ap. Soil pH decreased in the upper and increased in the lower soil profile when using solid fertilizer as compared to liquid fertilizer. Extractable Mg also decreased in the upper and increased in the lower soil profile when using solid compared to liquid fertilizer. Additional work is needed to characterize the relation between forage yield level, K removal on various soils for several years, and Coastal bermudagrass stand characteristics when the soil K reserves are exhausted.
The Nature of the Phosphate‐Goethite (α‐FeOOH) Complex Formed with Ca(H2PO4)2 at Different Surface Coverage
Authors: Parfitt R. L.
Published: July 2010

Basic information on the reaction between Ca(H2PO4)2, NaH2PO4, H3PO4, and the iron oxide goethite (α‐FeOOH) has been obtained prior to a study of the desorption of phosphate by plants. Infrared spectra of the wet phosphate‐goethite complexes suggested that the binuclear bridging complex was present with all these phosphates over the whole range from low surface coverage to maximum surface coverage. Maximum adsorption was observed when Ca(H2PO4)2 was used with 0.01M CaCl2 as the supporting electrolyte. The adsorption isotherms with phosphate and fluoride (NaF) reached a maximum value which indicated that there were 460 to 480 µmol of reactive A type OH groups on geothite. There was no evidence for phosphate adsorbed in any other form than the surface bridging complex which is formed very rapidly.
Errors in Determination of the Water Content of a Trickle Irrigated Soil Volume
Authors: Ben‐Asher J.
Published: July 2010

A short review of the possible methods of measuring soil water content under high frequency trickle irrigation suggested that the gravimetric method was most appropriate. Three sources of errors in this method have been evaluated and discussed. The sources are those of water content by weight, bulk density, and integration based on the sampling grid. Furthermore, as the sampling mesh became coarser the results became unstable because the differences in volume of water became larger than the defined standard deviation (SD). Error analysis of measurements on uniform Bet Dagan grumusol and sandy soils of Nahal Sinai (Israel) and Yuma (Arizona) showed that coefficient of variation in volume of water within an irrigated volume element may be reduced if the sampling grid is taken properly. The analysis suggests that for a given coefficient of variation and interval of sampling depth, an optimum distance between lateral samples can be evaluated from a mathematical reorganization of the coefficient of variation.
Field Measurement of Denitrification: II. Mass Balance and Sampling Uncertainty
Authors: Rolston D. E. , Broadbent F. E. , Goldhamer D. A.
Published: July 2010

Denitrification determined from the total production of volatile denitrification products was compared with denitrification determined from the difference of fertilizer addition, plant uptake, residual soil N, and leaching. Field plots on Yolo loam (Typic Xerorthents) were instrumented with soil atmosphere samplers, soil solution samplers, tensiometers, and thermocouples. Plots were maintained at two different water contents, at three different carbon levels (cropped, uncropped, and manure addition), and at two different temperatures. Fertilizer was applied at the rate of 300 kg N ha−1 as KNO3 enriched with 15N. The flux of gases at the soil surface was measured from the accumulation of N2O and 15N2 beneath air‐tight covers placed over the soil surface for 1 or 2 hours per day. Fertilizer N in plant, soil, and soil solution samples was determined from total N and 15N analyses. Soil 15NO3‐ vs. time and depth and soil‐water flux at several samplers were used to determine leaching of fertilizer N. Denitrification measured directly was generally 0 to 30 kg N ha−1 less than that determined by difference for the wetter treatments. For the drier treatments, denitrification measured directly was 12 to 65 kg N ha−1 less than that determined by difference due to the inability to measure very small gas fluxes of 15N2 over relatively long time periods and inability to continuously monitor gas fluxes. Uncertainties (95% confidence intervals) associated with the difference method were primarily due to the large sampling variability in leaching (±20–110% of applied N), although variability in soil residual NO3‐ (±5–30% of applied N) and residual organic N (±0–14% of applied N) measurements were also large. The uncertainty in the leaching component was also increased due to systematic error associated with overestimating the solute flux because of anion exclusion or immobile water. Although uncertainty in the direct method due to sampling variability (±0–30% of applied N) was less than that of the difference method, systematic errors may result in an underestimation of denitrification for some situations.
Overwinter Redistribution and Leaching of Fall‐applied Nitrogen
Authors: Bauder J. W. , Montgomery B. R.
Published: July 2010

Field studies were conducted on irrigated Maddock fine sandy loam (Udorthentic Haploboroll) to determine mineralization and nitrate leaching following fall application of N from Ca(NO3)2, (NH4)2SO4, and CO(NH2)2. Chloride was used to trace water and NO3‐ movement. Amount and distribution of NO3‐‐N present the following spring was considered an index of N mineralization and redistribution. Mass balance was used to determine loss during the overwinter period.

Predominant depth of leaching was 80 to 115 cm each year, although estimated effective precipitation was only 10 to 20% of the soil moisture storage capacity. Some solute was leached to 180 cm. Considerable NO3‐ leaching and redistribution was observed following fall application of Ca(NO3)2. Nitrate accumulation following (NH4)2SO4 and CO(NH2)2 application was restricted to the 0‐ to 30 cm depth. From October to April net NO3‐ accumulation attributed to nitrification and mineralization averaged 58.4 kg/ha per year. Cloride leaching was not affected by N source. On the basis of these results, NO3‐‐based N sources should not be applied in the fall on these well drained sandy soils since significant N leaching may result.
A Model for Predicting Packing Density of Soils Using Particle‐Size Distribution
Authors: Gupta S. C. , Larson W. E.
Published: July 2010

Many soil management decisions can be made from measured dry bulk density of the soil. These interpretations of soil behavior could be enhanced if soil particle‐size analysis could be used as a predictor of soil bulk density. A random‐packing model was developed utilizing soil‐particle size distribution as the principal input. Other inputs were average equivalent particle and cavity radii; bulk and particle densities of pure soil fractions determined under the same experimental conditions, like that of the final mixture; and concentrations of soil mineral and organic fractions. The model predicts random‐packing, maximum, and minimum bulk densities of a mixture of glass beads or soil fractions. Maximum and minimum bulk densities are limiting values not found in artificial or natural particle mixture. Tests of the random packing density with measured density showed a maximum deviation of 0.08 g/cm3 for multicomponent‐glass‐bead systems and 0.45 g/cm3 for mixtures of natural soil materials. Applications of the random‐packing model may delineate surface‐sealing susceptibility among soils of similar texture, describe the degree of profile devlopment among soils of different orders, and delineate soil profiles or horizons within a profile to pan formation susceptibility.
Dissolution and Stability of Biogenic Opal
Authors: Wilding L. P. , Hallmark C. T. , Smeck N. E.
Published: July 2010

Biogenic 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.
Inexpensive Four‐Electrode Probe for Monitoring Soil Salinity
Authors: Rhoades J. D.
Published: July 2010

Description is given of the construction and use of an inexpensive four‐electrode probe suitable for permanent installations and for in situ monitoring of soil salinity. Data illustrative of its use are presented.
Soil Nitrification Retardation by Rice Pesticides
Authors: Turner Fred T.
Published: July 2010

The 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

A 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

The 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

Liberia 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

Sweet 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

Problems 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

A 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

Metal‐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

A 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

A 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

Two 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

Soils 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

A 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

This 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

An 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

The 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

The 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.
A Comparison of Different Methods for Measuring Soil Salinity
Authors: Nadler A. , Dasberg S.
Published: July 2010

Soil salinity measurements with in situ salinity sensors, a four‐electrode salinity probe, a four‐electrode Wenner array, and a multi‐electrode probe were compared in an experimental plot irrigated with 3.1 mmho/cm CaCl2. Good agreement was obtained among expected salinity, soil extract (1:1) EC (electrical conductivity), and EC measurements with the salinity probe. The salinity probe requires good electrode‐soil contact and is therefore limited to the higher range of soil water contents. The Wenner array functions also at lower water contents, but interpretation of the results is influenced by soil layering. Salinity sensors gave the highest variance in the results.
Adsorption of Phosphate and Water‐extractable Soil Organic Material by Synthetic Aluminum Silicates and Acid Soils
Authors: Yuan T. L.
Published: July 2010

Three synthetic Al silicates with different Si/Al ratios and soil samples from a Eutrandept, a Paleudult, and a Haplaquod, were separately treated with P and hot water‐extractable soil organic materials. The Al silicate with the lowest Si/Al ratio retained the most P but the least organic materials. The Paleudult which had a lower P adsorption capacity retained more organic matter than the Eutrandept. The Haplaquod had the lowest P and organic matter retention.

Pretreatment of soils with organic material had varied effects on subsequent P adsorption. Pretreatment of soils with P reduced the adsorption of organic material, but at all organic matter levels the P adsorption was constant.

The findings suggested that the sites for organic matter and P adsorption may differ, but certain sites seem to adsorb both P and organic matter.
Predicting Native Plant Copper, Iron, Manganese, and Zinc Levels Using DTPA and EDTA Soil Extractants, Northern Great Plains
Authors: Gough L. P. , McNeal J. M. , Severson R. C.
Published: July 2010

The utility of DTPA (0.005M, pH 7.3) and EDTA (0.01M, pH 7.0) extractants for measuring the availability of Cu, Fe, Mn, and Zn from uncultivated A‐ and C‐soil horizons to western wheatgrass (Agropyron smithii Rydb.), silver sagebrush (Artemisia cana Pursh), and above‐ground biomass was assessed at 21 geochemically diverse sites in the northern Great Plains. Positive relationships between the extractable or the total concentration of these elements in soils to concentrations in plants, as measured by multiple regression, were limited. A‐horizon DTPA‐extractable levels of Fe and Mn were significant positive independent variables in the prediction of Fe and Mn levels in wheatgrass. C‐horizon DTPA extractable levels of Mn and Zn were significant positive independent variables in the prediction of Mn and Zn sagebrush levels. Multiple regression techniques never gave significant relations between EDTA‐extractable element levels and plant element levels; however, strong relations were observed between soil pH and metal concentrations in plants. The relation between plant metal concentration and A‐horizon pH was always positive and apparently related to soil levels of metal carbonates. These data indicate that caution should be used in the formulation of regulations for plant available levels of these metals in Great Plains soils based solely on extractable levels.
Phosphorus Application Rate and Distribution in the Soil and Phosphorus Uptake by Corn
Authors: Anghinoni I. , Barber S. A.
Published: July 2010

Evaluation of the effect of P addition and distribution in soil on P uptake by corn (Zea mays L.) plants, requires knowledge of the relation of soil P level to corn root growth rate and morphology. This research was conducted to obtain these relationships so that they could be used with root P influx and soil supply characteristics to calculate P uptake. Corn was grown for 12 and 18 days on two soils, each with five levels of P application, in pots in a controlled climate chamber. Root growth and P uptake were measured. Except for the lowest rate, increased rate of P mixed uniformly with the soil decreased average root length per pot even though shoot growth increased. Placing a common rate of P per pot in part of the soil volume increased root growth in the P‐treated soil volume as compared to root growth in the untreated soil. The difference was expressed by the relation y = x0.68, where y was the fraction of total plant root length in x, the fraction of the total soil volume that was P treated. Separate calculation of P uptake from each soil volume showed low P uptake from the untreated soil compared to that from the treated soil. Predicted P uptake per not calculated with a mathematical simulation model was correlated (r = 0.81 and 0.78 for the two soils) with observed P uptake. Information on effect of P on corn root growth and on P influx can be used in mathematical models to investigate relative P uptake from alternate P application practices.
Soil‐Geomorphic Relationships in the Western Margin of the Willamette Valley, Oregon
Authors: Glasmann J. R. , Brown R. B. , Kling G. F.
Published: July 2010

Geomorphology and soils were studied in a 285‐ha agricultural watershed lying between the 63‐and 135‐m elevations in the western Willamette Valley. Previously named geomorphic surfaces, strata, and soils are recognized, and the Brateng surface is introduced and defined.

The Irish Bend Member of the silty Willamette Formation is found only below the 80‐m elevation. The Greenback Member mantles the Irish Bend silts and higher portions of the landscape, thinning out at 122 m. A paleosol, developed from soft sedimentary rock of the Spencer Formation, lies beneath the Irish Bend and Greenback silts. Above the 80‐m elevation, the paleosol is part of the solum.

The concept of the late Pleistocene Bethel geomorphic surface, with which the Irish Bend silts are associated, is expanded to include low‐relief ridge spurs merging upslope with the Brateng surface. The Brateng surface, between 80 and 122 m, is mantled by late‐Pleistocene Greenback silts and thus is late Pleistocene in age. The mid‐Pleistocene Dolph surface is found above the 122‐m elevation.

Soils beneath the newly defined Brateng surface are mainly in the fine and fine‐silty Ultic Haploxeralfs and fine Aquic Xerochrepts. Soil mapping in the Brateng landscape is complicated by marked soil variability, a function of variations in thickness of surface silts, in degree of expression of the buried paleosol, and in texture of the underlying bedrock.
Fertilizer Fate in a 13‐year‐old Slash Pine Plantation
Authors: Shoulders Eugene , Tiarks Allan E.
Published: July 2010

Surface application of 403 kg N, 95 kg P, and 64 kg K per ha to a 13‐year‐old slash pine (Pinus elliottii Englem. var. elliottii) plantation on Caddo loam soil increased total volume growth during the next 6 years by 8.3 m3/(ha·year). Trees responded rapidly to the fertilizer; measurable differences in diameter growth developed by mid‐May. Fertilization markedly increased the amount of N, P, and K accumulated in current‐year needles during the first year after treatment. Fertilized trees continued to accumulate more P in current foliage for at least 8 years. Ratios of Rb/K in foliage indicated that K from the fertilizer comprised 27% of K accumulated in current‐year needles of fertilized trees during the fifth and sixth growing seasons, and 20% accumulated in the eigth. Ten months after treatment, added K had apparently disappeared from the top 13 cm of soil, but about half the added P remained available there. After 8 years, fertilized soil contained 40 ppm available P in the 0.9 cm layer; unfertilized soil contained only 2 ppm. In 8 years, fertilized plots accumulated 9.2 metric tons/ha more litter than did control plots. Litter had 50 kg/ha more N, 11.3 kg/ha more P, and 5.1 kg/ha more K than did litter on unfertilized plots. Disking to incorporate the fertilizer into the soil gave no advantage.
Comparison of Modified Urea Fertilizers and Estimation of Their Availability Coefficient Using Quadratic Models
Authors: Tejeda Hernan R. , Hong Chong W. , Vlek Paul L. G.
Published: July 2010

A procedure to compare N fertilizers based on comparing complete response curves simultaneously represented by a quadratic multifertilizer response model (MRM) is discussed. A modified version of the MRM, called fertilizer testing model (FTM), is used to test differences among response curves. The FTM describes the response curve to a fertilizer selected as a standard as well as the additional effect of test fertilizers over the response to the standard. In case of different response curves, an approximate test to decide whether the curves have equal limiting yield is introduced. Finally, a procedure to estimate the availability coefficient from quadratic response curves having equal limiting yield is derived.

These procedures were employed to analyze six field experiments conducted over a period of 3 years in Korea using three varieties of rice (Oryza sativa L. ‘Tongil,’ ‘Jinheung,’ and ‘Milyang 23’) and three fertilizers (urea and two sulfur‐coated ureas, or SCU) applied at four or five levels of N. Two out of six experiments showed a significant effect from SCU‐A (25% release/7 days) beyond that of split‐applied urea, whereas SCU‐B (14% release/7 days) showed significant additional effects in three out of five experiments. However, in four of these six experiments, the limiting yield of the response curves of SCU was significantly higher than that of urea, precluding a valid estimation of the availability coefficient. Possibly, the proper combination of N dose and timed release of N from SCU in these experiments translated into grain yields unmatched by split applications of urea.
Dissolution of North Carolina Phosphate Rock in Acid Colombian Soils as Related to Soil Properties
Authors: Chien S. H. , Leon L. A. , Tejeda H. R.
Published: July 2010

Information on the dissolution of phosphate rock in soils as related to soil properties is needed in order to understand the solubility behavior of the phosphate rock in soils as related to crop response. This study was conducted to determine the relationships between the dissolution rate of North Carolina phosphate rock and selected chemical properties of 16 acid Colombian soils. A modified Elovich equation, Ct =Co − (1/β) ln (αβ) − (1/β) ln t, was used to describe the dissolution of phosphate rock in the soils. In the equation, Ct is the P concentration in water extract at time t, Co is the maximum P concentration in the water extract when t→0, α and β are constants. Of the various soil properties studied, the best correlations of reactive Al were a simple linear relationship with β and a log‐log relationship with α. Results from tests with two other acid soils from Colombia showed these relationships allow prediction of the dissolution rate of the phosphate rock in other soils from a single measurement of reactive Al content.

Phosphorus sorption capacities of the 16 soils were correlated with amounts of reactive Al or active Al but not with amounts of free Fe2O3 and exchangeable Al in the soils. Amounts of water‐extractable P in the soils treated with concentrated superphosphate (CSP) or the phosphate rock decreased as P sorption capacity increased; however, the relative amounts of water‐extractable P of the phosphate rock with respect to CSP increased as P sorption capacity increased. This suggests that the relative agronomic effectiveness of phosphate rock compared with CSP would be highest on the strongly P‐fixing soils.