bluuebunny/crossref_metadata_2025 huggingface dataset:
Plant Uptake of Indigenous and Fertilizer Nitrogen from a Cretaceous Shale and Coal Mine Spoils
Authors: Reeder Jean Dolan , Berg W. A.
Published: July 2010

Barley (Hordeum vulgare L.) was grown in a greenhouse in incubated and nonincubated samples of a Cretaceous shale, two strip mine coal spoils, and a soil (Cryoboroll) to evaluate the significance to plant growth of indigenous N mineralization and utilization of added NH4+. These “soil” materials contained 730 to 1,190 ppm total N. Plants grown in the shale or fresh spoil took up less indigenous N than plants grown in vegetated spoil or in soil. Incubation did not significantly affect uptake of indigenous N from any of the four “soil” materials.

Less N added as NH4+ was taken up by barley growing in incubated than nonincubated samples of shale, fresh spoil, and vegetated spoil. Total‐N uptake from incubated “soil” material was positively correlated with NH4+‐N + NO3‐‐N contents of “soil” material samples after laboratory incubation for 12, 21, and 42 days.

This study indicated that while initial plant recovery of fertilizer N from the geologic materials equaled that recovered from the soil, fertilizer N added to the geologic material may be less available to plants with time than the same amount of fertilizer N added to soil. The high correlations between mineral N contents of laboratory‐incubated samples and total N uptake by barley grown under greenhouse conditions suggested that laboratory incubation tests could be useful in estimating the plant‐available N potentials of certain drastically disturbed lands prior to extensive revegetation programs.
Nitrogen Mineralization and Nitrification in a Cretaceous Shale and Coal Mine Spoils
Authors: Reeder Jean Dolan , Berg W. A.
Published: July 2010

Knowledge of rates and amounts of N mineralization in geologic strata is needed to predict N availability to plants when these materials are disturbed by mining or construction and left as surface or subsurface plant‐growth media. Laboratory incubations were conducted to determine ammonification and nitrification rates in a Cretaceous shale, two strip‐mine coal spoils, and a soil from a strip mine in northwestern Colorado. The total N concentration in the soil (1193 ppm), a vegetated spoil (1,083 ppm), and the shale (1112 ppm) were similar, while that of the fresh spoil was lower (730 ppm). No net N mineralization was measured in the shale, and less than 6 ppm NO3‐‐N accumulated in the fresh spoil during a 168‐day incubation. However, net mineralization of 49‐ppm NO3‐‐N was found in the vegetated spoil and 75‐ppm NO3‐‐N in the soil during the same incubation period.

Nitrification of added NH4+ (60 ppm NH4+‐N) was measured in the shale, spoils, and soil. Accumulated levels of NO3‐‐N were 100 ppm in the vegetated spoil and 117 ppm in the soil after a 168‐day incubation. However, only 36‐ppm NO3‐‐N accumulated in the fresh spoil and no NO3‐‐N accumulated in the shale during the same incubation period.

Rates and total amounts of CO2 evolution from the geologic materials resembled that from the soil, indicating considerable heterotropic microbial activity in these geologic materials. The addition of NH4+ did not significantly affect the rate or amount of CO2 evolution from the geologic or soil materials, indicating that heterotropic microorganisms were capable of using the forms of N present in the geologic materials.
Subgroup Designation of Three Udolls in Southeastern Nebraska
Authors: Lewis David T.
Published: July 2010

The Wymore, Pawnee, and Mayberry soil series are presently placed within the fine montmorillonitic mesic family of Aquic Argiudolls. However, the major properties of these soils that affect their interpretations are related to a clay content in the argillic horizon that exceeds 40%, a consequent high shrink swell potential, and a droughty nature. The wide cracks that develop during most summer seasons affect runoff and water entry into the profile thereby making the moisture control section meaningless in them. COLE and potential linear extensibility values for these soils along with their other properties suggest that perhaps Vertic of Ustertic subgroup designations would more accurately describe their properties and interpretation of these properties.
Soil Salinity—Four‐electrode Conductivity Relationships for Soils of the Northern Great Plains
Authors: Halvorson A. D. , Rhoades J. D. , Reule C. A.
Published: July 2010

Influence of soil texture, soil geographic location and parent material, and calibration method on the linear ECe‐ECa relationship was investigated. Linear regression relationships between saturation extract electrical conductivity (ECe) and bulk soil electrical conductivity (ECa) as measured by the four‐electrode technique were developed for northern Great Plains soils. Most correlation coefficients (r) exceeded 0.95 and all were significant at the 0.01 probability level. Geographic location had little effect on the ECe vs. ECa relationship; therefore, an ECe vs. ECa calibration made for a soil textural class at one location will apply to another location having a similar range in soil water, clay content, and salinity. Clay content affected linear regression line slopes more than did other factors investigated. Regression slopes varied from 3.06 for a clay to 12.99 for a loamy sand over the clay concentration range of 63.0 to 6.5%, respectively.

To minimize adverse effects caused by natural variation in soil texture, water content, and salinity when making field ECe vs. ECa calibrations, we suggest artificial salinization of columns of the soil type in question, which will permit subsequent analysis of the soil by either the cell or EC‐probe calibration method.
A Direct Field Measurement of Ammonia Emission After Injection of Anhydrous Ammonia
Authors: Denmead O. T. , Simpson J. R. , Freney J. R.
Published: July 2010

Studies of the efficiency of applications of anhydrous ammonia fertilizer require a measurement of ammonia retention or loss at the time of application. Because of sampling problems, conventional measurements based on soil analysis are difficult to make in the field. A new method is described, based on calculating the aerial transport of ammonia across the downwind edge of the treated field from measurements of wind speed, wind direction, and atmospheric ammonia concentration. Ammonia losses as small as 1 kg N/ha can be easily detected. Maximum errors are reckoned at no more than 20%. In a field experiment in which anhydrous ammonia was applied at 107 kg N/ha, aerial sampling gave a loss of 1 kg N/ha. Soil sampling detected no loss because of a large sampling error (SE 15 kg N/ha).
Organic Phosphate Transport and Hydrolysis in Soil: Theoretical and Experimental Evaluation
Authors: Castro C. L. , Rolston D. E.
Published: July 2010

An understanding of the movement, hydrolysis, and retention of organic phosphates in soils is necessary to evaluate possible advantages of the compounds as fertilizers, based upon their characteristic of increased vertical movement over that of inorganic phosphates when applied with irrigation water. Pulses of chloride and glycerophosphate were applied to 4‐, 10‐, and 20‐cm long Panoche clay loam (Typic Torriorthents) soil columns maintained slightly water‐unsaturated (soil‐water pressure = −0.018 bar). The concentration of glycerophosphate in the pulse applications varied from 386 to 1,110 ppm P. An analytical solution assuming first‐order kinetics and a reversible, linear isotherm for glycerophosphate hydrolysis and sorption, respectively, was compared with measured glycerophosphate concentrations in the column effluent. An analytical solution of the coupled equations for simultaneous transport of organic phosphate and orthophosphate assuming a linear, reversible isotherm for orthophosphate adsorption is given. This solution was compared with measured orthophosphate concentrations in the effluent from a continuous application of glycerophosphate to a 2‐cm long column. Organic phosphate adsorption on soil colloids was effectively separated from organic phosphate hydrolysis using displacement techniques. The magnitude of the fitted, first‐order constant for hydrolysis was dependent upon the initial concentration of the influent solution indicating that first‐order kinetics may not be applicable for high organic phosphate concentrations. The magnitude of the fitted, adsorption‐desorption constant for glycerophosphate was dependent upon concentration indicating that adsorption‐desorption was nonlinear. The nonlinearity of glycerophosphate adsorption‐desorption was verified from an equilibrium, adsorption isotherm. The magnitude of the fitted orthophosphate sorption constant for coupled glycerophosphate and orthophosphate transport was considerably larger than that determined from a 6‐day equilibrium adsorption isotherm.
Dissolution of Phosphate Rocks in a Flooded Acid Soil
Authors: Chien S. H.
Published: July 2010

Seven phosphate rocks from widely separated locations were used to investigate the dissolution of phosphate rocks in an acid, P‐deficient soil (Mountview silt loam, pH 4.8) under waterlogged conditions. The phosphate rock was added at a rate of 400 ppm P in the soil. The objective of the study was to investigate the way in which the P concentration in the soil solution equilibrated with the various phosphate rocks was related to the apatite composition and the citrate solubility of the phosphate rocks used.

The concentration of P in the soil solution equilibrated with various phosphate rocks during incubation varied considerably among sources of the rock, ranging from 0.03 to 0.35 ppm in 1 week and 0.04 to 0.11 ppm in 10 weeks after the soil was flooded. The solubility differences of various phosphate rocks decreased as incubation time increased.

The P concentrations in the soil equilibrated with phosphate rocks reached a maximum 1‐3 weeks after the soil was flooded. There was a linear relationship (r = 0.93) between the logarithm of the maximum P concentrations in the soil solution equilibrated with phosphate rocks and the degree of carbonate substitution for phosphate in the apatite structure of the phosphate rocks used. A highly significant linear correlation (r = 0.95) was found between the maximum P concentration in the soil solution and the citrate solubility of the phosphate rocks used. The correlation, however, decreased to 0.82 in 10 weeks after the flooding. Apparently, factors other than apatite composition were also affecting the dissolution of phosphate rocks in the soil solution after prolonged incubation.
Phosphorus Fractions in Selected Nigerian Soils
Authors: Udo E. J. , Ogunwale J. A.
Published: July 2010

The distribution of total, organic, and various inorganic phosphorus forms was determined for six Nigerian soil profiles selected to cover different ecological zones and geological formations. Total P was generally low in most of the profiles ranging from 144 to 791 ppm. The basaltic Dogon Gaba soil contained the highest amounts while the soil formed on sedimentary deposits had the lowest values. The relative abundance of the extractable inorganic fractions was generally in the order of occluded P > Fe − P > Al − P > Ca − P except in Dogon Gaba and Agbaru (Etinan) where Al − P was more abundant than Fe − P and in Egbeda with Ca − P more important than Al − P (the latter being negligible in this soil). A large fraction of the inorganic P remained in the nonextractable or residual form especially in soils from the savanna region. Organic P was low in the soils from the savanna zone, but high in those soils from the forest region. The high percentage of occluded and residual P and the low level of active P indicated a high degree of weathering and a low available P status of the soils.
Correction for Dissolved Nitrous Oxide in Nitrogen Studies
Authors: Moraghan J. T. , Buresh R.
Published: July 2010

Rapid methods for the accurate determination of N2O in atmospheres of closed incubation flasks are now available. However, serious errors in measuring total N2O within a closed system may arise if dissolved N2O is not considered. Temperature and the ratio of solution volume to atmosphere volume are important factors determining the magnitude of errors resulting from this cause. A simple formula for calculating dissolved N2O based on solution and atmosphere volumes, the mass of N2O in the gaseous phase, and published solubility data for N2O in water is presented. If the chemical composition of the solution phase is likely to influence solubility coefficients, these values can be experimentally determined using a described technique.
Solute Transport Through Soil With Nonuniform Water Content
Authors: De Smedt F. , Wierenga P. J.
Published: July 2010

An approximate analytical solution is presented for steady flow of salt through soil with a nonuniform distribution of the water content. The solution is in good agreement with a numerical computer solution, provided by the CSMP simulation language. Both solutions also agree with the analytical solution for soils with a uniform distribution of the water content. It is shown that effluent curves from soil profiles, with the same average water content and leached at the same steady rate, are basically the same and thus independent of the variation of the water content in such profiles.
Cumulative Effects of Nitrogen, Phosphorus, and Potassium Fertilizer Additions on Soil Respiration, pH, and Organic Matter Content
Authors: Van Cleve Keith , Moore Terry A.
Published: July 2010

Cumulative effects of annual additions of NH4NO3 (111 kg/ha N), treble superphosphate (55 kg/ha P), and KCl (111 kg/ha K) on aspen (Populus tremuloides Michx.) soil respiration, pH, and soil organic matter content were examined. Total fertilizer additions from fall 1969 through spring 1975 were 777 kg/ha N and K and 385 kg/ha P.

The main effect of N and P additions was to increase soil biological activity by up to 42% and 33%, respectively, with the greatest increases occurring at the 15‐ to 30‐cm soil depth. For K, a 21% reduction in soil biological activity occurred at 0‐ to 15‐cm, while a 20% increase was found at 15‐ to 30‐cm. Fertilization with N and P increased but K showed no effect on surface soil organic matter content. Subsurface soil (15‐ to 30‐cm) organic matter content was not affected by any treatment. Higher soil organic matter content probably resulted largely from greater aspen growth response to N. Increased soil biological activity was attributed to a combination of increased soil organic matter content and improved levels of soil N and P.

Treatment with N, K, or N + K reduced soil pH, possibly because of microbial nitrification of NH4+ associated with uptake by aspen of NH4+ and K+ with replacement of H+ in the soil.
Comparative Foliar Analysis of Young Balsam Fir Fertilized With Nitrogen, Phosphorus, Potassium, and Lime
Authors: Timmer V. R. , Stone E. L.
Published: July 2010

Foliar analyses of individually fertilized balsam fir trees [Abies balsamea (L.) Mill.] were examined to explain significant growth responses and nutrient status changes. Treatments consisted of factorial combinations of N, P, and K, and one separate treatment of dolomitic lime. Simultaneous comparisons of first year changes in foliar nutrient concentration, content, and dry weight simplified assessment of deficiency, dilution, and luxury consumption. N fertilization increased both needle dry weight and N composition, but lowered foliar P, K, Ca, and Mg concentrations by dilution. Additions of P and/or K did not change needle weight and led to luxury consumption of P and K. Lime alone had no measurable effect in the first year. Overall correlations between foliar concentration and content of individual nutrients accounted for 68–78% of the total variability for foliar P, K, Ca, and Mg, but 99% for foliar N which was unaffected by dilution. A concentration of 2.1–2.3% N in current foliage is the approximate upper limit for growth response for these balsam fir trees.
Leguminous Plants Increase Sycamore Growth in Northern Alabama
Authors: Haines Sharon G. , Haines L. Wayne , White Gordon
Published: July 2010

Tree growth in a 2‐year‐old sycamore (Platanus occidentalis L.) plantation in northern Alabama significantly increased over the following 4 years after three clovers and two vetches were grown with the trees. Leguminous plants were chosen to: (i) provide weed control through good ground coverage, (ii) maintain a low profile, (iii) grow during the cool season so as not to compete with the sycamore, (iv) provide cover for several years after establishment through their ability to reseed, and (v) make additional nitrogen (N) available through the fixation process. Following establishment of the leguminous plants, sycamore height and volume growth were increased as were N concentrations in sycamore foliage. Of the plants tested, Mississippi subterranean (Trifolium subteraneum L.) and crimson clovers (T. incarnatum L.) gave good ground coverage, maintained a low profile, reseeded themselves well, and increased the N content of sycamore foliage in addition to improving height and volume growth.
An Improved Moistening Technique for Aggregate Stability Measurement
Authors: Mubarak A. , Klages M. G. , Olsen R. A.
Published: July 2010

An ultrasonic nebulization technique has been used for uniform wetting of soil by introduction of an aerosol. Values obtained for aggregate stability of air‐dried soils were greater when this technique was used than with conventional wetting techniques, apparently because of reduced slaking effect.
Nutrient Effectiveness in Relation to Rates Applied for Pot Experiments: I. Nitrogen and Potassium
Authors: Terman G. L. , Mortvedt J. J.
Published: July 2010

An N source experiment was conducted on infertile Mountview sil (Typic Paleudult) to evaluate four N sources at multiple rates of applied N and P. Granular ammonium nitrate (AN), sulfur‐coated urea (SCU), oxamide (Ox), and isobutylidene diurea (IBDU) were evaluated for corn (Zea mays L.) at N rates of 0, 400, 800, and 1,200 mg/pot (5 kg of soil), each at P rates of 0, 60, 120, 480, and 960 mg/pot. Yield response to applied N was in the order AN >> SCU > Ox > IBDU at the higher rates of applied P. At 60 and 120 mg of applied P/pot, however, P was too deficient for satisfactory evaluation of the N sources. In an experiment with flooded rice (Oryza sativa L.), P limited yields less than did N. In other N‐P and P‐K factorial experiments, rates of other nutrients and length of growth period also greatly affected crop response to applied N and K. These results show that satisfactory evaluations of N or K sources are possible only at adequate rates of nontest nutrients. Nutrient rates adequate for small greenhouse pots are much higher than rates equivalent to normal rates recommended for crops grown under field conditions. Length of growth period and other growth‐limiting factors are equally important.
Hydraulic Conductivity of Soils: Unified Approach to the Statistical Models
Authors: Mualem Y. , Dagan G.
Published: July 2010

Conceptual theory of the hydraulic conductivity of unsaturated porous media is presented. This analysis permits us to derive systematically the models of R. C. Childs and N. Collis George (1950), M. R. J. Wyllie and G. H. F. Gardner (1958) and Y. Mualem (1976) as well as other existing and new versions, from some common statistical principles.

The resulting formulas of unsaturated hydraulic conductivity can be classified into three categories: (i) universal formulas independent of the soil type which result from extremely simplifying assumptions; (ii) formulas with one degree of freedom, and (iii) formulas with two degrees of freedom. The latter two types of equations result from accounting for the correlation between pores and the tortuosity of flow path. These formulas can be adjusted to soil type to represent better the variability of soil properties and increase the accuracy of the predicted hydraulic conductivity. However, in this stage it is a potential advantage only. Empirical study should be followed in order to derive the optimal methods of estimating the unknown parameters.
Water Redistribution in Partially Frozen, Saturated Silt Under Several Temperature Gradients and Overburden Loads
Authors: Loch J. P. G. , Kay B. D.
Published: July 2010

The flux of water and the resultant formation of discrete ice lenses were studied in samples of New Hampshire silt which were saturated and then frozen under different temperature gradients and overburden pressures. A dual energy gamma scanning system was employed to locate the position of the growing ice lens relative to the freezing front. Parameters controlling water flow and the location of the ice lenses were employed to evaluate theories that have been proposed to describe the mechanisms of ice lens formation. The capillary theory was employed to locate the freezing front. However, the ice lenses were found to be located 0.2–0.4 cm behind the freezing front, which is inconsistent with the location of the ice lenses predicted by the capillary theory. Neither the hydrodynamic theory, nor the secondary frost heaving theory account for the redistribution of overburden pressure between soil particles, ice, and water. These theories cannot be employed to predict the location of the ice lens relative to the freezing front until overburden pressure effects are incorporated into the theory.
Influence of FeEDDHA on Growth and Manganese Accumulation in Flax
Authors: Moraghan J. T. , Freeman T. J.
Published: July 2010

A lower leaf‐scorch abnormality, resembling Mn toxicity, was observed in flax (Linum usitatissium L.) plants growing on certain calcareous soils. The cause of this problem was studied in greenhouse experiments using a naturally occurring, slightly calcareous (pH 8.1) soil. Above‐ground parts, but not roots, of afflicted plants contained relatively high levels of Mn. Addition of 2 ppm FeEDDHA‐Fe eliminated the appearance of brownish spots on the distal portions of older leaves and subsequent leaf necrosis, decreased Mn accumulation in above‐ground plant parts, and increased yields. Ammonium molybdate (0.05 and 0.5 ppm Mo) had no effect on the severity of the abnormality or on Mn accumulation. Cytological examination of brown spots showed distortion of chloroplast membranes, absence of starch, decrease in grana membranes, absence of plastid ribosomes, and increase in plastoglobuli. It is hypothesized that the lower leaf scorch was caused by Mn toxicity. Flax, in the absence of FeEDDHA, was a Mn‐accumulator plant even though the soil in question was calcareous. Available soil Fe level appeared to be a dominant factor influencing Mn accumulation by flax.
Influence of Vegetation on Water Repellency in Selected Western Wisconsin Soils
Authors: Richardson J. L. , Hole F. D.
Published: July 2010

Water repellency in several western Wisconsin soils was characterized by three tests: wetting angle (θ), wetting drop penetration‐time (WDPT), and 90°‐surface tension (γη). It appears that the high contents of organic matter in the A horizon of Mollisols and Alfisols are associated with slight repellency as measured by θ and WDPT. Frequent burning of a prairie on a Mollisol increased persistence (WDPT) and γη, as compared with soil at a nearby control site, but had no influence on θ, indicating that repellency is present at initial water contact but is unstable and disappears with prolonged water contact.

Mor litter layers having observable fungal mycelia had repellent surfaces as measured by all three of the above tests. These repellent materials were observed in Spodosols under red pine (Pinus resinosa), hemlock (Tsuga canadensis), and under a mixed hard and soft wood stand with dense ericaceous shrub understory. The repellency of mor horizons of Spodosols may relate in some significant way to process of genesis of Spodic horizon.
Nitrogen Mineralization and Uptake from Douglas‐Fir Forest Floors
Authors: Youngberg C. T.
Published: July 2010

Many different plant species grow in the understory in association with Douglas‐fir [Pseudotsuga menziesii (Mirb.) Franco]. The nature of the forest floor that accumulates in a Douglas‐fir forest is influenced by these associated species. Nitrogen uptake from forest floor materials developed under nine commonly occurring stand understory conditions was evaluated in a greenhouse experiment with Douglas‐fir seedlings. The net mobilization of N as measured by the uptake of N by two successive crops of Douglas‐fir seedlings ranged for 0.34 to 9.89% of the amount added as organic matter. Net N mobilization was related only partially to total N content of the material.
Proposed Changes in Sandy Textural Class Definitions
Authors: Franzmeier D. P. , Norton L. D.
Published: July 2010

According to present definitions of USDA textural classes, some sandy particle‐size distributions can not be placed in any class. We propose changes in the definitions of fine sandy loam, sandy loam, loamy sand, and sand so that all distributions can be classified, facilitating computer computation of texture classes.
Solute Transport During Absorption of Water by Soil: Laboratory Studies and Their Practical Implications
Authors: Smiles D. E. , Philip J. R.
Published: July 2010

An experimental study of solute transport during absorption into uniform horizontal soil columns is reported.

Three pairs of experiments were performed. Each pair had a common initial moisture content (0.04, 0.1, or 0.15), with one experiment involving displacement of concentrated soil solution by dilute solution and the other, vice versa.

In all experiments, both the soil solution content and the salt concentration preserved similarity in terms of distance divided by square root of time. This confirmed earlier observations that the longitudinal dispersion coefficient for the conditions of these experiments is effectively independent of volume flux density. These results were found to be consistent with the studies of Saffman (1959) and Pfannkuch (1963) on transport during steady flow.

The inferred dispersion coefficient is essentially independent also of the volumetric moisture content (at least in the range 0.18–0.28). It is approximately equal to the product of the volumetric moisture content and the molecular diffusivity of KCl in water.

The practical implications of the work for field problems are explored, use being made of scaling theory for flow processes involving capillarity and viscous flow. It is concluded that, for the majority of field soils, solute transport during unsaturated flow of any practical duration may be described by a velocity‐independent dispersion coefficient. This represents a very great simplification of the formulation, analysis, and prediction of solute transport in such systems.

The observed pistonlike displacement of the initial water in the columns by the absorbed water suggests that there is no basis for subdividing the water in the system into mobile and immobile fractions.

Further theoretical and experimental work is under way on solute transport during infiltration, and during absorption into very coarsetextured soils (for which the dispersion coefficient is not velocity independent).
Transient Changes in the Soil‐water System from Irrigation with Saline Water: I. Theory
Authors: Jury W. A. , Frenkel H. , Stolzy L. H.
Published: July 2010

Transient soil solution concentrations and salt precipitation rates in the root zone are shown to be influenced by the ion composition and concentration of the applied water and soil exchange complex as well as by the water uptake distribution and infiltration rate. Calculations are performed on three kinds of infiltration water to estimate the ionic composition of the soil solution, the rate of gypsum and CaCO3 precipitation, and the time to reach steady state for a given irrigation management. Solution concentrations adjusted for exchange interactions were shown to precipitate twice the quantity of salt in a given time, resulting in lowered solution concentration and altered composition of Ca2+, Mg2+, Na2+, and SO42‐ ion concentrations in the solution phase, with up to 1,600 days required to reach steady state through the top 150 cm for a leaching fraction of 0.05. The extent of precipitation is also found to depend strongly on the concentration of sulfate and degree of saturation with gypsum in the irrigation water. Diffusion and dispersion are also shown to influence the duration of the transient phase.
Water Harvesting for Afforestation: I. Efficiency and Life Span of Asphalt Cover
Authors: Mehdizadeh P. , Kowsar A. , Vaziri E. , Boersma L.
Published: July 2010

The water required to irrigate greenbelts being established around cities in Iran is a major cause of concern in a country with insufficient supplies. Methods of afforestation which do not require irrigation must be found. One such method is to concentrate water, received by a watershed without vegetation, for distribution over a smaller area where plants are growing by making portions of the watershed area impervious to water through application of asphalt. This principle was tested on runoff plots 2 m wide and 10 m long. Runoff from each plot was measured to study its variations as a function of age of asphalt cover and rainfall amount and intensity. The concept was further tested by constructing 2‐m wide terraces along contour lines at 5‐m intervals on a hillside with a slope of about 30%. Tree species, ecologically adapted to the area, were planted on the terraces. Calibrated gypsum blocks were placed at depths of 15, 30, 45, and 60 cm in the terraces and at depths of 10 and 30 cm in the watershed area between the terraces to measure soil water potentials.

As the asphalt membrane aged, its efficiency in inducing runoff decreased. The runoff efficiency was nearly 75% initially, but decreased to 25% after 4 years. A regression equation was obtained correlating the runoff efficiency with age of the asphalt membrane. Freezing and thawing of the soil, growth of plants, and shrinking and swelling of clays resulted in the deterioration of the membrane. It remained effective for about 5 years.

The runoff from the asphalt‐sprayed microwatersheds resulted in high soil water contents of the terraces, with average potentials of −0.4, −7.7, and −2.5 bars during 1972, 1973, and 1974 where runoff was received, corresponding to −7.7, −23.8, and −21.8 bars on control plots.

The technique is being developed as an alternative to the irrigation practices now in use for the establishment of greenbelts. It will result in savings of water, which in some localities could amount to 5,000 m3/ha/year, an amount sufficient to satisfy the needs of 50 people per year.
Relationship of Extractable Soil Manganese to Soil Properties
Authors: Shuman L. M. , Anderson O. E.
Published: July 2010

In a greenhouse experiment eight Southeastern soils were amended to give pH levels of 4.8, 5.8, and 6.8 and were treated with 0, 25, and 50 ppm Mn. After growing wheat (Triticum aestivium L.) for 40 days, the soils were extracted for Mn using six extractants: H2O, neutral 1N NH4OAc (with and without 0.2% hydroquinone), “double acid”, diethylenetriaminepentaacetic acid (DTPA) and ethylenediaminedi‐o‐hydroxyphenylacetic acid (EDDHA). Except for the low‐Mn soils, greater differences in extractable Mn were observed among soil types and soil pH levels than among Mn rates. Extractable Mn was correlated with soil clay content and total soil Mn. Organic matter content with a narrow range from 1.0 to 2.9%, silt content and cation exchange capacity (CEC) were not correlated with extractable Mn. The extractable Mn decreased as soil pH increased for the H2O, NH4OAc alone, and DTPA extractants making them preferable for predicting soil Mn availability since higher pH causes Mn to be less available to the plant.
Iron Oxide Mineralogy of Well‐drained Ultisols and Oxisols: I. Characterization of Iron Oxides in Soil Clays by Mössbauer Spectroscopy, X‐ray Diffractometry, and Selected Chemical Techniques
Authors: Bigham J. M. , Golden D. C. , Bowen L. H. , Buol S. W. , Weed S. B.
Published: July 2010

The iron oxides in subsoil clays (<0.2 µm) from five North Carolina Ultisols and two Brazilian Oxisols were analyzed by Mössbauer spectroscopy, X‐ray diffractometry, and selected chemical techniques. Goethite and hematite were identified as the dominant crystalline iron oxides in these clays. Partial substitution of Al(III) or other nonmagnetic ions for Fe(III) in the oxide structures caused reduced unit cell dimensions and subnormal effective internal magnetic fields. All samples exhibited strong superparamagnetic relaxation, a collapse of the Mössbauer magnetic splitting at ambient temperatures due to the ultrafine size of the oxide particles. Negligible amounts of iron were solubilized with acid ammonium oxalate; however, the Ultisol clays did contain significant amounts of silicate and/or interlayer iron that was not extractable with dithionite‐citrate‐bicarbonate.
Ammonia Exchange Over a Corn Crop
Authors: Denmead O. T. , Nulsen R. , Thurtell G. W.
Published: July 2010

A micrometeorological technique was used to calculate the net transfer of NH3 between a corn crop and the atmosphere. On the 10 days of measurement, there was continual interchange of NH3 between crop and atmosphere with a strong indication of a diurnal cycle. Ammonia absorption by the plant‐soil system (downward transfer of NH3) predominated when the soil surface was dry, but sustained losses of NH3 (upward transfer) occurred when it was moist. Net absorption rates of 6.6 g N ha−1 hour−1 were calculated in the former period, and net losses of as much as 27.6 g N ha−1 hour−1 in the latter.
Chloride as a Factor in Mobilities of Ni(II), Cu(II), and Cd(II) in Soil
Authors: Doner H. E.
Published: July 2010

An investigation was undertaken to study the mobility of chlorocomplexes of Ni(II), Cu(II), and Cd(II) through soil. Soil columns were leached with 0.1, 0.2, 0.3, or 0.5M NaCl or NaClO4 solutions, each containing 10 µg/ml Ni(II), Cu(II), or Cd(II). Sodium perchlorate solutions were used as a comparison with NaCl at the same ionic strength since perchlorate is not considered to form complexes with the metals. Leachates from columns and soils were collected and analyzed. Mobility of all metals tested in chloride solutions was from 1.1 to 4 times greater than that in ClO4‐ solution. Chloride increased the mobility of Cd(II) the most which corresponds to its having the largest stability constants. Cooper (II) was slowest to appear in the leachate and was strongest adsorbed as evidenced by analysis of soil by digestion with either 4N HNO3 or acidified NH2OH‐HCl. These results showed that Cl‐ has a marked effect on the mobility of Cd(II) and, to a lesser extent, Ni(II) and Cu(II).
Structural Study of Humic Acids by X‐ray, Electron Spin Resonance, and Infrared Spectroscopy
Authors: Eltantawy I. M. , Baverez M.
Published: July 2010

Composts and soil humic acid structures were examined by X‐ray, ESR, and IR methods. X‐ray diffraction showed three bands at 3.6, 2.1, and 1.2Å for the studied humic acids. These bands occured on the same position as the (002), (10), and (11) of carbon black and were ascribed to aromatic structure or graphite‐like layers. The presence of a 7.5Å band in the X‐ray diffraction of the examined humic acids indicate to nonaromatic fraction too. IR spectra confirm the presence of aromatic and aliphatic fractions associated with various types of functional groups including quinone groups. The nature of these groups are discussed. ESR signal G ∼ 2 indicates the presence of free radicals within the humic substances, whereas very little is known about the ESR signal at G ∼ 4.125 observed in the studied humic acids. This signal was attributed to Fe3+ chelated to humic substances. Compost and soil humic acids showed some structural differences.
Soil Temperatures in Adjacent High Elevation Forests and Meadows of Montana
Authors: Munn L. C. , Buchanan B. A. , Nielsen G. A.
Published: July 2010

Little published data exist reporting growing season soil temperatures under native vegetation in the Northern Rocky Mountains. In this study soil and air temperatures were measured in meadow, ecotone, and forest vegetation at 2,300 m elevation on the Bangtail Ridge near Bozeman, Montana. Mean annual soil temperature measured at 50 cm was 3.0°C for meadow sites, 2.6°C for ecotone, and 1.8°C for forest sites. Winter soil temperatures for the three types were similar but summer soil temperatures were nearly 5° C warmer in meadows than in forests and intermediate in the ecotone. Temperature variation was greatest in the meadow, intermediate in the ecotone, and least in the forest.
Flow Patterns During Extended Saturated Flow in Two, Undisturbed Swelling Clay Soils with Different Macrostructures
Authors: Bouma J. , Wösten J. H. M.
Published: July 2010

Large, undisturbed soil columns with an average height of 30 cm, a diameter of 25 cm, and with two different types of macrostructure were sampled in moist clay soil. Type 1 had vertical wormchannels and “rough” peds; type 2 had no worm channels and “smooth” peds. Flow patterns were characterized by repeatedly measuring Ksat and chloride breakthrough curves. Effective pore size distributions were calculated from the latter with the Klinkenberg procedure.

Initial chloride breakthrough was most rapid in soil columns of type 1 after displacement of < 1 vol. % of the initial water, whereas 3 vol. % was displaced in type 2. Rapid chloride breakthrough was associated with a high volume of immobile water (60 vol. % and 2 vol. % for types 1 and 2 respectively). These phenomena can be explained by the presence of relatively large, continuous pores (particularly in type 1), that occupy only a small volume, as was confirmed by micromorphometric analysis and calculations of effective pore diameters. Application of a gypsum crust on soil columns of type 1 erased the differences with type 2. Crusts induced pressure potentials of __5 mbar, thus excluding the largest pores only. Extended ponding and associated continued swelling of peds did not change flow phenomena in type 1; in type 2, Ksat, the volume of immobile water and the effective pore diameters gradually decreased. Equivalent pore diameters, calculated from the soil moisture characteristic, were quite different from the effective diameters and could not be used to independently predict the breakthrough curves. Direct measurement of the latter and empirical extrapolation to soils with identical texture, mineralogy, and macrostructure is recommended for field work because replicate columns, sampled in a large geographical area and with the two types of macrostructure, showed significantly different flow phenomena.
Decomposition of Microbial Cells and Components in Soil and Their Stabilization Through Complexing with Model Humic Acid‐Type Phenolic Polymers
Authors: Nelson D. W. , Martin J. P. , Ervin J. O.
Published: July 2010

Axenic cultures of bacteria, yeasts, and filamentous fungi were cultured on 14C‐glucose‐peptone medium. Cells were fractionated into cell wall and cytoplasm components and the components were complexed into model phenolic polymers or intimately mixed with preformed polymers prior to incubation in soil. Whole cells, cell walls, and cytoplasm fractions readily decomposed in soil; by 12 weeks of incubation from 50 to 79% of added 14C had evolved as 14CO2. Complexing of cell walls with polymers prepared from hydroxybenzoic acids and from hydroxytoluenes plus phenols reduced decomposition an average of 31 to 56%, respectively. Incorporating cytoplasm components into phenolic polymers reduced decomposition by an average of 49%. Intimately mixing cell walls with preformed polymers prepared from hydroxybenzoic acids and from hydroxytoluenes reduced decomposition an average of 14 and 28%, respectively. Mixing cytoplasm components with preformed polymers reduced decomposition by an average of 11%. Addition of whole cells or cellular components did not increase the decomposition of native soil organic matter. A higher proportion of residual 14C after incubation was recovered in the humic acid fraction in samples treated with cell walls complexed into phenolic polymers as compared to samples receiving uncomplexed cell walls. The implications of the study with regard to humus formation in soils are discussed.
Studies in Soil Manganese: II.: Extractable Manganese and Plant Uptake
Authors: Salcedo I. H. , Ellis B. G. , Lucas R. E.
Published: July 2010

Results from a greenhouse pot experiment with 12 Michigan and Indiana soils of different characteristics were used to evaluate effectiveness of six extractants in predicting Mn uptake by soybean (Glycine max., cv. Hark) plants. Three levels of Mn as MnSO4 were added to each soil. Correlation between extractable Mn and uptake of Mn by plants decreased in the following order: 0.1N H3PO4 > steam/1N NH4OAc > 1.5M NH4H2PO4 > 0.1N HCl > 1N NH4OAc > 0.005M DTPA. Inclusion of pH and (Ca+Mg)/K ratio in prediction equations for each soil test increased percentages of variation in uptake data explained by the tests. Of the soil characteristics, Mn oxide fractions explained 66% of the variation in Mn uptake; inclusion of pH, bases ratio and total Mn in the equation accounted for 82% of this variation. Critical levels of extractable Mn in these soils were 12 ppm for 0.1N H3PO4 and 14 ppm for steam/1N NH4OAc or 1.5M NH4H2PO4.
Determination of Map Unit Composition by a Random Selection of Transects
Authors: Steers C. A. , Hajek B. F.
Published: July 2010

A procedure for random sampling of mapping units and a statistical method for analyzing field data have been evaluated in five Alabama soil surveys. Taxonomic composition, consistency of delineations, and minimum number of transects needed for mapping unit characterization were determined by routine field examination, investigation of randomly selected transects, and statistical analysis of field data. The method requires that soil delineations be identified by landscape features with minimum traversing and observations and that potential transects (transects that may be selected for study) be located while mapping. Each delineation is represented by at least one potential transect; potential transects should traverse areas that represent the concept of a mapping unit. These transects make up the total available population of a mapping unit. From this population, randomly selected transects are sampled for detailed study. A minimum of 10 point observations is made on each. This procedure has shown that many mapping units in a survey area can be characterized at 80% confidence level by determining soil occurrence along less than 10 transects. In some cases it may be necessary to group soil series into similar interpretive units to reduce transect numbers and to present data that can be used.
Derivation of the Langmuir Equation for Ion Exchange Reactions in Soils
Authors: Sposito Garrison
Published: July 2010

The form of the Langmuir adsorption isotherm equation that is appropriate for ion exchange reactions is derived rigorously using statistical mechanics. It is shown that, in addition to the usual assumptions of localized, monolayer adsorption and no interactions between adsorbed ions, the restriction that the exchange process be one‐to‐one must be imposed. However, there is no inequality condition on the equilibrium solution concentrations and affinity parameters for the exchanging ions as has been suggested previously by several investigators. The Langmuir equation is valid for all nonzero values of the ion activities and affinity parameters.
Analytical Properties of the Soluble, Metal‐Complexing Fractions in Sludge‐Soil Mixtures: IV. Determination of Carboxyl Groups in Fulvic Acid
Authors: Holtzclaw Kenneth M. , Sposito Garrison
Published: July 2010

A detailed experimental examination of the titration behavior and reaction with calcium acetate of a series of model organic acids led to the conclusion that the standard Ca(OAc)2 method for the determination of COOH groups in organic matter would be ineffective for sludge‐derived fulvic acid. In particular, it was shown that positive interferences from SO3H groups and acidic OH groups could be expected. A modified Ca(OAc)2 method was developed, consisting of: (i) conversion of fulvic acid to K/H fulvate, (ii) reaction with 1N calcium acetate, (iii) distillation of the acetic acid product, and (iv) titration of the acetic acid with 0.1N NaOH, in which these positive interferences do not occur. The modified method was applied successfully to two representative sludge‐derived fulvic acids, a soil‐derived fulvic acid, and two model humic polymers, all of which exhibited positive interferences with the standard Ca(OAc)2 method.
Bacterial Effects on Hydraulic Conductivity of Soils
Authors: Frankenberger W. T. , Troeh F. R. , Dumenil L. C.
Published: July 2010

Laboratory experiments were performed to determine the relationship between bacterial pore clogging and soil hydraulic conductivity. When soils were submerged and hydraulic conductivity was plotted against time, the conductivity decreased and eventually stabilized at a constant value. The time required, the stable value, and the coefficient of variability were all influenced by the treatment applied to the soil. Sterile soils had the highest hydraulic conductivity and lowest C. V. of all treatments. The lowest hydraulic conductivity resulted from the addition of both a C and a N source. Continuous submergence and wetting and drying cycles were compared in their effects on hydraulic conductivity. A specific portion of the total biological activity (as determined by the acid phosphatase assay) and a selective bacterial population (accounted for by the medium used) were significantly and negatively correlated with hydraulic conductivity. As the bacterial population and phosphatase activity increased, the hydraulic conductivity decreased. The decrease in hydraulic conductivity under prolonged periods was primarily due to the excretion of metabolic products produced by bacteria within the soil pores.
Sand Content of Sand‐Soil‐Peat Mixtures for Turfgrass
Authors: Taylor D. H. , Blake G. R.
Published: July 2010

Soils subjected to intensive foot‐traffic in areas used for sports usually require modification in order to maintain physical properties conducive to turfgrass growth. Commonly this is achieved by mixing soil with large quantities of sand and often some peat. Though present recommendations for quantity of sand are made using a great deal of experience, published supporting information is limited. The purpose of this research was to provide additional data.

Seven sand‐soil‐peat mixtures were prepared giving a series that varied in sand contents from 75 to 97% by weight and in which organic matter remained essentially constant. A 35‐cm layer of sand‐soil‐peat mixture underlain by a gravel layer was placed in large pots and bentgrass (Agrostis palustris, Huds.) was established. Mixtures were watered as needed and were compacted daily for 53 days to simulate foot‐traffic, following which degree of compaction and infiltration rate were measured. Saturated hydraulic conductivities, variation in air‐filled pore volumes with water potential, and bulk densities of extracted core samples were also measured. Turfgrass yield and quality as well as root growth were evaluated.

The data show that under the experimental conditions, sand‐soil‐peat mixtures having 87% or more sand by weight provided infiltration rates of 2.3 cm/hour or greater, and air‐filled porosities of 10% or greater at a soil water potential of −30 mbars. Sand‐soil‐peat mixtures with 87% sand gave as good turfgrass growth as those with greater amounts although the mixtures with > 90% sand supplied a greater safety margin for infiltration rate. Lower sand contents resulted in poorer grass yields, low infiltration rates and low drainable porosities.

This minimum acceptable value of 87% sand by weight in a sand‐soil‐peat mixture was found using a predominantly medium sand, Nicollet loam soil and reed‐sedge peat. This value could vary with different sands and soils due to differing compaction characteristics and clay types.