bluuebunny/crossref_metadata_2025 huggingface dataset:
Sulfuric Acid Treatment of Calcareous Soils: Effects on Phosphorus Solubility, Inorganic Phosphorus Forms, and Plant Growth
Authors: Ryan John , Stroehlein Jack L.
Published: July 2010

The purpose of this study was to examine the effects of acid (H2SO4) application on three P‐deficient calcareous Arizona soils. The acid was mixed with the soils in order to reduce their respective buffering capacities, as measured by the acid titratable basicity (ATB), by 20, 40, 60, 80, and 100%. Two soils, Cave and Comoro, were cropped with tomatoes (Lycopersicum esculentum) after treatment. Significant responses in dry matter yield and P uptake persisted through three successive growth periods. Treatment significantly increased water‐soluble P and P‐supplying‐capacity of the soils. Increasing the H2SO4 rate reduced the H2SO4‐P fraction, increased NH4Cl‐P and NH4F‐P, and to a lesser extent NaOH‐P but had little effect on reductant soluble‐P. Both extractable Al and Fe increased with increasing amounts of H2SO4 applied. Though difficulties may be encountered in field application, these results show that H2SO4, a waste product mainly from the copper smelting industry, has potential for improving P‐deficient calcareous soils.
Microbial Effects on Soil Erodibility
Authors: Gasperi‐Mago Rafael Ricardo , Troeh Frederick R.
Published: July 2010

This study was undertaken to evaluate the effects of three microbial species on soil erodibility. Sterilized Ames (a Typic Albaqualf) and Nicollet (an Aquic Hapludoll) soils were inoculated with species of Pseudomonas, Streptomyces, and Penicillium. After 15 days of incubation, both treated and untreated soils were subjected to artificial rainfall to measure their erodibility. The Ames soil averaged 23% more runoff and 34% more sediment in the runoff than Nicollet, but 2.25 times as much Nicollet soil as Ames soil was caught on splashboards. Soil loss from sterile soil was more than from any other treatment, and that from the fungal treatment was the least. The unsterilized soil had runoff and erosion approximately equal to the average of the bacterial, actinomycetes, and fungal treatments used. The results show that all of the microbial treatments used had significant positive effects on erosion resistance and that the Penicillium sp. had the strongest effect.
Soil Water in Coarse Fragments
Authors: Hanson Carolyn T. , Blevins R. L.
Published: July 2010

The amount of availability of water contained in coarse fragments is often considered to be negligible, but may in fact play an important role in the water relations of soils containing numerous coarse fragments. The objective of this study was to measure the availability of water contained in two contrasting types and several size fractions of fragments. Field capacity, −15 bar potential, and wilting point (WP) measured by plant extractions were made on sandstone fragments from the surface layers of Cutshin soil and shale fragments from a Colyer soil. The sandstone fragments contained about 11% available water by volume, and the shaly fragments contained 23% available water by volume based on WP measurements by plant removal in the greenhouse. The −15 bar potential determined in the laboratory compared closely with WP measured by plant removal for the sandstone fragments, but the −15 bar potential indicated higher levels of moisture retained in the shale fragments than WP as determined in the greenhouse.
A Simplified Ethylene Glycol Monoethyl Ether Procedure for Assessment of Soil Surface Area
Authors: Cihacek L. J. , Bremner J. M.
Published: July 2010

Studies with 33 soils selected to obtain a wide range in properties showed that the surface area values obtained by an ethylene glycol monoethyl ether (EGME) procedure that omitted the customary pretreatments to remove organic matter and saturate the soil sample with Ca2+ were similar to, and very highly significantly correlated with, the values obtained when these time‐consuming pretreatments were included. The surface area values obtained by the simplified EGME procedure were very highly significantly correlated with the clay contents and cation‐exchange capacities of the soils studied.
The Use of a Transformed Boundary Condition in Modelling Air Compression During Infiltration
Authors: Watson K. K. , Curtis A. A.
Published: July 2010

A computer‐based numerical analysis incorporating a time‐dependent surface boundary condition transformation is of value in modelling the air compression effects which occur during ponded infiltration in bounded columns. However, the transformation requires clarification when used with materials which exhibit a well‐defined water entry value. Since the capillary pressure head has no meaning in the saturated zone, which develops from the surface downwards during the infiltration process, it is necessary to define a pseudocapillary pressure head for this zone. This concept assists in developing a consistent qualitative argument showing that the one‐phase, one‐dimensional analysis accurately models the bounded flow regime. The condition which governs the termination of the analysis upon air escape is also considered.
Solubility and Equilibria of Zinc in a Flooded Soil
Authors: Gilmour J. T. , Kittrick J. A.
Published: July 2010

Soil solution composition data were obtained for flooded Crowley silt loam soil. These data were analyzed with a computer program which corrected for ion‐pair formation and computed soil solution Zn activities at 0, 50, and 90% complexation by soluble organic species. The computed values were compared to predicted soil solution Zn activities which would occur if ZnCO3(c), Zn2SiO4(c), Zn3(PO4)2·4H2O(c), or ZnS(c) were the controlling solid phase. Under flooded soil conditions, ZnS(c) was the only possible solid phase which could be controlling soil solution Zn activity, assuming that the H2S(g) pressure in the soil solution was similar to that of atmospheric air [pH2S(g) = 10.3] and that between 50 and 90% of solution Zn was complexed by organic species. Under laboratory conditions where H2S(g) levels were thought to be much lower than unpolluted air, both Zn2SiO4(c) and ZnCO3(c) appeared to be potential solid phases. Zinc phosphate, Zn3(PO4)2·4H2O,(c), was too soluble to control solution Zn in this soil.
The Microbiological Formation of Basic Ferric Sulfates: II. Crystallization in Presence of Potassium‐, Ammonium‐, and Sodium‐Salts
Authors: Ivarson K. C. , Ross G. J. , Miles N. M.
Published: July 2010

Solutions of ferrous sulfate (pH 2.95) containing equivalent amounts of K+, NH4+, or Na+, either singly or in pairs, were inoculated with the iron‐oxidizing bacterium (Thiobacillus ferrooxidans) and allowed to incubate for 42 weeks. Successive quantitative analyses of the alkali cations in the single cation systems showed that after 3 to 4 weeks, virtually all of the K+ in solutions had reacted to form jarosite [KFe8(SO4)2(OH)6]. On the other hand, after 42 weeks, about 80% of the NH4+ and 60% of the Na+ had entered into their respective basic ferric sulfates—ammoniojarosite [NH4Fe3(SO4)2(OH)6] and natrojarosite [Na Fe3 (SO4)2(OH)6]. Progressive increases in peak intensities of the resultant X‐ray diffractograms and rates of acid production in solution agreed very well with rates of jarosite formation. In systems containing two alkali cations, solid solutions formed and the rate at which each cation disappeared from solution was similar to that in the single cation systems.

The results are in accord with reported field analyses of acid sulfate soils, i.e., jarosite is the most abundant basic ferric sulfate in these soils and the soils invariably contain Fe2+ and T. ferrooxidans.
Effect of Moisture on the Survival of Rhizobium in Soil
Authors: Osa‐Afiana L. O. , Alexander M.
Published: July 2010

Rhizobium trifolii and Rhizobium japonicum survived in higher numbers in Collamer silt loam at 10% than at 22, 35, and 45% moisture levels. The rate of R. trifolii decline at the three higher moisture levels was initially rapid, but then the rate slowed. At 22, 35, and 45% moisture, fewer R. trifolii and R. japonicum survived in nonsterile than in sterile soil, and indigenous protozoa grew in response to addition of the root‐nodule bacteria to the nonsterile silt loam. The rate and extent of decline of both species in flooded soil were more marked if sucrose was added; in such soil, R. trifolii died more rapidly and its population reached lower numbers. Bdellovibrio was not detected as the rhizobial density declined. Butyric, acetic, propionic, and formic acids accumulated and the pH fell below 6.0 in the sugar‐amended flooded soil, but no marked accumulation of the first three microbial products and no comparable pH fall occurred in flooded soil receiving no sucrose. Liming the sugar‐amended flooded soil enhanced R. trifolii survival but still led to organc acid accumulation. The data suggest a role for protozoa at moderate moisture levels and for organic acids acting at low pH in flooded soils in the decline of Rhizobium populations.
Decomposition in Soil of Emodin, Chrysophanic Acid, and a Mixture of Anthraquinones Synthesized by an Aspergillus glaucus Isolate
Authors: Linhares L. F. , Martin J. P.
Published: July 2010

A. glaucus synthesized 17 – 22 anthraquinones, and one to four phenolic compounds depending on cultural conditions and incubation time. The anthraquinones extracted from the culture media were equivalent to 10% or more of the total mycelium plus melanin polymers recovered. Based on two‐dimensional thin‐layer chromatography and cochromatography with reference compounds before and after separation on a silica gel column and on UV spectra, dominant anthraquinones included emodin, catenarin, physcion, erythroglaucin, endocrocin, and probably parietinic acid and questin. One of the phenols was orcinol. The anthraquinone mixtures, synthesized by A. glaucus under different cultural conditions, were only slowly degraded in soil. During a 12‐week incubation period the C losses ranged from 11 – 23%, while 69 and 47%, respectively, of emodin and chrysophanic acid C were evolved as CO2. Emodin when “linked” into peroxidase polymers was relatively stable to biodegradation during the earlier stages of incubation only. When in intimate physical association with a model humic acid‐type polymer, little protection was observed. The 14C‐labeled A. glaucus anthraquinone mixture when “linked” to phenolase polymer showed a biodegradability reduction from about 25 – 11% during 12 weeks.
Effect of Camping on Surface Soil Properties in the Boreal Forest Region of Northwestern Ontario, Canada
Authors: Monti P. W. , Mackintosh E. E.
Published: July 2010

Changes in surface soil properties along a gradient of increasing intensity of recreational use was investigated for two vegetation units, Pinus banksiana and Populus tremuloides, in the Boreal Forest Region of northwestern Ontario. The initial changes involve the compression and loss of surface leaf litter followed by formation of a thin, compacted mineral layer at the soil surface. Porosity photograms show that the content of macropores in the size range 300 to >3,000 µm were reduced by up to 60% in this layer, and pores >2,000 µm were almost entirely eliminated. Infiltration rates were correspondingly reduced to 0.1 cm/hour.

The importance of processes operating at the leaf litter‐mineral soil interface in this environment are emphasized and discussed in relation to development of campsite rehabilitation programs.
A Thermal Conductivity Probe Designed for Easy Installation and Recovery from Shallow Depths
Authors: Sophocleous Marios
Published: July 2010

Existing designs of thermal conductivity probes were modified in order to build a probe suitable for easy installation and recovery from shallow depths above or below the water table in unconsolidated deposits. The performance of the thermal conductivity probe described here was compared to a recent probe design with satisfactory results; it was also successfully tested in the field.
An Analytical Solution to Solute Transport Near Root Surfaces for Low Initial Concentration: II. Applications
Authors: Cushman John H.
Published: July 2010

Examples are presented to illustrate the affects of changing the outer radius (r1), and the ratio of root absorbing power to inward flux of water (k/vo) on nondimensional concentration as a function of nondimensional time and distance. The examples presented are based on the analytical solution to two flow situations (see Part I). A method is also presented to show how simple solutions can be constructed for the flow problem involving only trigonometric functions.
Effect of Montmorillonite and Trace Elements on the Growth of Penicillium frequentans: I. Ammonium Nitrogen Source
Authors: McCormick R. W. , Wolf D. C.
Published: July 2010

In laboratory studies, the addition of clay to culture media has been shown to increase microbial growth and metabolic activity. The objective of this study was to determine the influence of montmorillonite clay and three trace element treatments on the growth of Penicillium frequentans with NH4‐N as the N source.

The fungus was grown in 100 ml of a defined basal medium with glucose as the carbon‐energy source and NH4Cl as the N source. The trace element treatments were (i) no trace elements, (ii) trace‐element solution 1 which contained the following final concentration of trace elements (µg/ml): FeSO4·7H2O, 0.20; ZnSO4·7H2O, 5.0; CuSO4·5H2O, 0.02; CoSO4·7H2O, 0.02; Na2MoO4·2H2O, 0.02; and H3BO3, 0.10; and (iii) trace element solution 2 which contained a 0.1M pH 6.0 phosphate buffer plus the following final concentration of trace elements (µg/ml): Fe2(SO4)3·nH2O, 10.0; ZnSO4·7H2O, 2.5; CuSO4·5H2O, 0.5; CoCl2·6H2O, 1.5; Na2MoO4·2H2O, 2.5; H3BO3, 0.5; MnSO4·H2O, 1.0; and CaCl2, 10.0. Either clay, at a concentration of approximately 500 mg/100 ml, or distilled water (controls) was added in dialysis tubing to the trace‐element treatments.

In the no trace element treatment, the biomass of the control was increased from 624 to 1,211 mg with the addition of clay. In the trace‐element solution 1, biomass was increased from 1,084 to 1,197 mg with the addition of clay. In both treatments, the addition of clay increased CO2 evolution, glucose and N utilization, and the economic coefficient of cell synthesis. Neither biomass nor metabolic activity was increased in the trace element‐solution 2 with clay addition. There were no significant differences in biomass production among the no trace element treatment with clay, the trace‐element solution 1 with clay, and the trace‐element solution 2 with or without clay. Except for the trace‐element solution 2, which contained a phosphate buffer, the addition of clay resulted in a decrease in the pH of the medium. In all three treatments, the addition of clay increased the Cu and Fe content of the fungus. With the addition of clay, the Zn content of the fungus increased in all treatments except the trace element solution 1. After fungal growth, the structural Zn and Cu contents of the clay, in the no trace‐element treatment, were reduced from 51 to 21 µg/g and 37 to 21 µg/g, respectively.

It appeared that P. frequentans removed trace elements from the clay for growth which accounted for a large portion of the stimulation in growth due to clay.
Effect of Temperature on the Gaseous Nitrogen Products of Denitrification in a Silt Loam Soil
Authors: Keeney D. R. , Fillery I. R. , Marx G. P.
Published: July 2010

The amount and relative proportion of N2 and N2O evolved from a nitrate‐amended surface soil under an atmosphere of He in the range of 7 to 75°C was examined. The objective was to evaluate the effect of temperature on N2O evolution and investigate the optimal temperature for denitrification. The soil had 2.43% organic C and pH of 6.8. Incubations were performed in all‐glass systems which were sealed throughout the incubation period. Denitrification products (N2O, NO, and N2) were determined periodically by gas chromatography using an ultrasonic detector. At the end of the incubation period, inorganic N remaining was determined.

Above 15°C, the rate of denitrification increased with temperature, with an apparent optimum of 60 to 67°C. The percentage as N2O of the total (N2O + N2)‐N declined with time, but was still 44 to 50% of the gas produced at 16 days with the 7 and 15°C experiments. Nitrous oxide comprised up to 88% of the gas produced at 40°C after 2 days. At 50°C, most of the gas was N2O at one day, but at 60 to 67°C, N2O had disappeared by 1 day. Denitrification was still occurring at 70°C, but at a reduced rate. More than 85% of the N evolved at 70°C was as N2O. No denitrification occurred at 75°C.

At 50 to 67°C, much more N was recovered as gaseous N than was initially present in the system as NO3‐N, and no (NO2‐+NO3‐)‐N remained at 4 days. These results are explained by the hypothesis that thermophilic Bacillus sp. (and perhaps others) rapidly reduces NO3‐ to NO2‐, with the NO2‐ reacting with oxidized N functional groups to form nitrogenous gases. This hypothesis was partially confirmed by experiments involving treatment of steam‐sterilized soil with NO2‐ at 40 and 60°C. Our results suggest that the commonly‐stated optimal temperature for denitrification may be too high for true biological denitrification due to the dominance of temperature‐dependent chemical reactions at >50°C.
Activity of Immobilized Pronase in the Presence of Montmorillonite
Authors: Griffith S. M. , Thomas R. L.
Published: July 2010

The activity of soluble and immobilized pronase in the presence of montmorillonite was examined using a differential spectrophotometric technique over a 100‐sec incubation period. On the basis of equivalent amounts of enzyme protein, the immobile enzyme had only 28% of the activity of the soluble pronase in the absence of clay. However, in the presence of clay, the immobile pronase was much less inhibited, retaining an average of 75% of its activity while the soluble pronase retained only 31% of its activity. The differential spectrophotometric procedure was satisfactory for monitoring the enzyme action in the presence of suspended clay.
Critical Levels of Soil‐ and Nutrient‐Solution Calcium for Vegetative Growth and Fruit Development of Florunner Peanuts
Authors: Wolt J. D. , Adams Fred
Published: July 2010

The separate effects of rooting‐ and fruiting‐zone Ca upon vegetative growth and fruit yield of ‘Florunner’ peanuts (Arachis hypogaea L.) were investigated in nutrient‐solution experiments where rooting and fruiting media were segregated. At low levels of rooting‐zone Ca, both vegetative and fruit growth were influenced by rooting‐ and fruiting‐zone Ca acting in concert. As root zone Ca was increased above the “critical” level for maximum vegetative growth, the plant changed from being almost fruitless to a well‐fruited plant.

Results of nutrient‐solution studies in the growth chamber were verified in a greenhouse soil experiment using surface soil of a Dothan loamy sand (Plinthic Paleudult). Composite results from soil and nutrient‐solution experiments identified three separate “critical” solution Ca levels. Expressed as the activity ratio of Ca/total‐cations, the levels were: 0.10 for vegetative growth, 0.15 for flower fertility or fruit load, and 0.25 for pod fill. Substituting K for Mg in solution caused a lowering of the “critical” Ca levels.
Effect of Vegetation on the Morphology of Windsor Soils, Litchfield, Connecticut
Authors: Johnson Arthur H. , Siccama Thomas G.
Published: July 2010

Eastern hemlock (Tsuga canadensis) on outwash sand in Litchfield County, Connecticut produced a more acid forest floor and throughfall with a greater capacity to mobilize Fe than American beech (Fagus grandifolia) or white pine (Pinus strobus). White pine produced the least acid forest floor, and throughfall with the least capacity to mobilize Fe. These characteristics were reflected in the order of A2 and Bhir horizon thicknesses which was hemlock > beech > pine.
Effect of Tillage on Soil‐Water Movement During Corn Growth
Authors: Weatherly A. B. , Dane J. H.
Published: July 2010

The occurrence of drought during the growing season often limits the amount of soil water available for plant growth. The availability of soil water can further be limited if a hard layer exists not too far below the soil surface. Field experiments were therefore conducted on a Cahaba sandy loam soil (Typic Hapludult) to determine the effect of tillage practices on soil water movement during corn (Zea mays L.) growth. Four tillage practices, viz., conventional‐tillage‐without‐subsoiling, conventional‐tillage‐with‐subsoiling, no‐tillage‐without‐subsoiling, and no‐tillage‐with‐subsoiling, were studied on a soil with a plow plan. Soil water contents and soil water pressure heads were measured with a neutron probe and tensiometers, respectively. Water extraction by roots was determined by application of the integral form of the general transport equation for soil water. Soil water movement and water uptake were less for the conventional‐tillage‐without‐subsoiling treatment than for the other treatments. The two subsoiled treatments and the no‐tillage‐without‐subsoiling treatment indicated root penetration and soil‐water uptake below 50 cm.

When soil water uptake patterns were compared with corn yield on a weight‐per‐ear basis, there was a direct, positive correlation between the amount of water taken up by the corn plants and corn yield.
Fluorine Distribution with Depth in Relation to Profile Development in Illinois
Authors: Omueti J. A. I. , Jones Robert L.
Published: July 2010

Fluorine content increases with depth, evidently in response to pH‐related absorption of F that has weathered from minerals in all size fractions of the upper solum. This relationship with soil colloids creates depth distribution characteristics of F that closely follow soil development trends that are especially well expressed by clay content. Fluorine attributed to organic matter in A and B horizons amounted to 9 µg/g of organic matter.
Nitrification Inhibition by N‐Serve and ATC in Soils of Varying Texture
Authors: Guthrie T. F. , Bomke A. A.
Published: July 2010

Although numerous laboratory studies have demonstrated the effectiveness of certain nitrification inhibitors, many field studies have failed to show any significant crop response to inhibitor treatments. Most field studies to date have only evaluated N‐serve [2‐chloro‐6‐(trichloromethyl)pyridine], which cannot be conveniently applied with solid fertilizers due to its volatility. ATC (4‐amino‐1,2,4‐triazole) is a nonvolatile, water‐soluble nitrification inhibitor which can be easily coated onto solid fertilizers without volatilization loss. The objective of this research was to compare the effect of N‐serve and ATC on silage corn (Zea mays L.) production and nitrification rates in two soils (silt and loamy sand). Urea was coated with the inhibitors at a rate of 1% of active ingredient per weight of N and applied as a band or broadcast in the spring of 1977 and 1978. The NH4‐N/NO3‐N ratio in the soil was calculated for each sampling date as an indicator of inhibitor effectiveness. Neither inhibitor significantly affected nitrification when applied as a broadcast treatment to either soil. In the silt, both inhibitors were equally effective in delaying nitrification when banded, but in the loamy sand ATC had a five times higher NH4/NO3 ratio than N‐Serve 3 weeks following application. The effectiveness of N‐Serve persisted much longer in the silt (86 days) than in the loamy sand (23 days). This suggested that volatilization of N‐Serve severely limited its effectiveness in the loamy sand. There was no significant improvement in crop yields or N content due to inhibitor treatment in either soil.

ATC is recommended for further field evaluation in conjunction with band‐applied solid fertilizers, particularly in coarse‐textured soils.
Summertime Flooding Effects on Alfalfa Mortality, Soil Oxygen Concentrations, and Matric Potential in a Silty Clay Loam Soil
Authors: Meek B. D. , Donovan T. J. , Graham L. E.
Published: July 2010

Soil oxygen levels and soil water matric potentials were measured at the 15‐, 30‐, and 60‐cm depths in plots subjected to flooding times of 15, 25, 35, and 45 hours. A decrease to 6% O2 or less in the soil for > 24 hours resulted in substantial losses of alfalfa (Medicago sativa L.). Soil O2 content decreased more at the 15‐cm depth as compared with the 30‐ or 60‐cm depths because of higher matric potential. The critical matric potential that restricted O2 movement was about −11 cbars.
Solubility of Plutonium Compounds and Their Behavior in Soils
Authors: Rai Dhanpat , Serne R. J. , Moore D. A.
Published: July 2010

The solubilities of 239PuO2 (c) (crystalline) and 239Pu(OH)4 (am) (amorphous) under natural environmental conditions were determined. These data were then used to predict the (i) nature of the solid phases present in contaminated soils, and (ii) total concentration of Pu that can be expected in soil solutions when these Pu solids are present.

Based upon solubility measurements, an estimated value of the log Kc (equilibrium constant at room temperature and an approximate ionic strength of 0.0045) for the dissolution of 239PuO2(c) [PuO2(c) ⇋ PuO2+ + e‐] was found to be −14.8. The estimated value of the log Kc for the dissolution of 239Pu(OH)4(am) [Pu(OH)4(am) ⇋ PuO2+ + 2 H2O + e‐] was found to be −12.8.

Comparison of Pu concentration in equilibrium solutions of contaminated Hanford soils with the PuO2(c) and Pu(OH)4 (am) solubility lines suggested that Pu(OH)4(am) was absent from all the samples and that two of the samples contained PuO2(c). The presence of PuO2(c) was also confirmed by X‐ray diffraction of Pu particles isolated from one of the samples.
Effects of Lime, Silicate, and Phosphorus Applications to an Oxisol on Phosphorus Sorption and Ion Retention
Authors: Smyth T. Jot , Sanchez Pedro A.
Published: July 2010

Greenhouse and laboratory experiments conducted with a clayey kaolinitic isohyperthermic Typic Haplustox from the Cerrado region of Brazil showed that CaCO3, CaSiO3, and previous P applications decreased P fixation and improved cation retention properties. The amendments were added at rates to replace 1 or 2× exchangeable Al, and P was applied at rates to provide equilibrium solution concentrations of 0, 0.05, 0.1, and 0.2 ppm P. Six months after application, CaCO3 and CaSiO3 at 1× exchangeable Al decreased the amount of previous P sorbed to provide 0.1 ppm P in solution by 18 and 24%, respectively. Previous P applications were more effective in decreasing P sorption than the amendments. A 540 ppm P rate decreased P sorption by 65% without amendments. The combination of amendments + 540 ppm P decreased P sorption by 85 to 91%. Fertilizer P recommendations based on soil solution levels for limed soils should be obtained with soil samples which have also been limed; otherwise the P requirement may be overestimated.

Net negative soil charges increased by 11 to 47% with amendment applications and by 34% with 540 ppm P. The highest P and amendment rates doubled the net negative charge of this soil. Joint applications of P and soil amendments increased the negative charge and decreased the positive charge to a greater extent than when applied separately. Applications of both P and amendments made a major improvement in cation retention against leaching, but may increase anion leaching. P applications significantly increased soil pH and negative ΔpH values.
Enumeration, Effectiveness, and pH Resistance of Rhizobium meliloti Populations in Oregon Soils
Authors: Barber Lynn E.
Published: July 2010

The number of Rhizobium meliloti cells in the soil of alfalfa (Medicago sativa L.) fields and the effectiveness and pH resistance of strains of R. meliloti isolated from the soil were analyzed for their relationships to soil parameters. Soil samples were collected from three alfalfa‐growing areas of Oregon and analyzed for pH, exchangeable H, soil bases, P, N, and organic matter content, and cation exchange capacity. The number of infective R. meliloti cells was estimated using the plant‐infection assay. The nodulation effectiveness of each isolated R. meliloti strain was ranked using alfalfa growth response in tube culture and in comparison to uninoculated no N and N‐amended controls. The ability of each strain to initiate growth in media adjusted to pH values of 4.5, 5.0, 5.5, 6.0, and 6.5 was determined. The number of R. meliloti cells in the soil was greater with increased soil pH and with decreased age of the alfalfa stand. Although the average ability of the strains of rhizobia to initiate growth at low pH increased with age of the alfalfa stand from which they were isolated, the strain effectiveness decreased with stand age. Average effectiveness of the strains increased with inoreased soil percent base saturation and with decreased soil exchangeable H, N, and organic matter contents.
Scaling Soil Hydraulic Properties of a Heterogeneous Field
Authors: Russo David , Bresler Eshel
Published: July 2010

Field data for soil water characteristics and hydraulic conductivity have been scaled by two methods. The set of scaling factors (αj) determined by one method depends on soil water content. A correlation of r2 = 0.86 is obtained between scaling factors determined from soil characteristic data and those determined from hydraulic conductivity data. In the second method, the set of αj is normally distributed, and is highly correlated with αj obtained by the first method from water characteristic data at water contents near saturation. In one method the sum of squares, about an average curve, was reduced by 44 and 66%, for the water characteristics and hydraulic conductivities data, respectively, while 92 and 82.5% reduction was obtained by the second method, for the same respective data. The results suggest that in practice, a single stochastic variable may represent the hydraulic properties of a heterogeneous field.
Metal Binding Properties of Leaf Litter Extracts: II. A Bioassay Technique
Authors: Blaser P. , Landolt W. , Flühler H.
Published: July 2010

A biological method is proposed to determine the maximum Cu binding ability and the conditional stability constant of leaf litter extracts. Free cupric ions reduce the 14CO2‐uptake of algae. In the presence of complex forming organic substances the observed depression of the relative CO2 uptake can be considered as a measure of the unbound ionic Cu concentration. Comparing the CO2‐uptake response function of solutions, with and without organic constituents spiked with variable amounts of Cu, yields a functional relationship between bound and free Cu. These functions can be interpreted with a sequential form of the Langmuir equation from which the maximum binding ability and the conditional stability constant are obtained. The presence of algae, modifies the complexing parameters, indicating that the values measured with nonbiological methods require careful interpretation when their significance in natural soils is considered.
Comparison of Extractants for Plant‐available Zinc, Cadmium, Nickel, and Copper in Contaminated Soils
Authors: Haq A. U. , Bates T. E. , Soon Y. K.
Published: July 2010

The objective of this study was to find a suitable extractant(s) for plant‐available metals in metal contaminated soils. Swiss chard (Beta vulgaris L. ‘Fordhook Giant’) was grown in greenhouse pots on 46 Ontario soils varying in degree of contamination with metals. The soils had been contaminated with metals to varying degrees over a period of years. After 40 days, the plants were harvested and Zn, Cd, Ni, and Cu concentrations were measured. Each soil was extracted with nine different extractants: aqua regia, 0.01M EDTA, 0.005M DTPA, 0.02M NTA, 0.5N CH3COOH, 1N CH3COONH4, 0.6N HCl + 0.05N AlCl3, (COOH)2 + (COONH4)2, and H2O. Zinc, cadmium, nickel, and copper concentrations in Swiss chard were correlated with the amounts of soil Zn, Cd, Ni, and Cu removed by each extractant. Of the nine soil extractants, CH3COONH4 was the best predictor of plant‐available Zn if only extractable Zn and soil pH were included as independent variables in a regression equation. Acetic acid was the best extractant for prediction of both plant‐available Cd and Ni when soil pH was included in the equation. Attempts to find a suitable soil extractant for plant‐available Cu were unsuccessful.
Effects of Nitrogen, Phosphorus, and Lime on the Forest Floor and Growth of Pole‐size Loblolly Pine
Authors: Van Lear D. H.
Published: July 2010

Changes in the nutrient content of the forest floor and tree growth were studied after application of N P, and lime to a pole‐size loblolly pine (Pinus taeda L.) plantation in the South Carolina Piedmont. Nutrients move with varying speeds through the forest floor. Nitrogen broadcast at a rate of 56 kg/ha could not be detected in the forest floor after 10 months, but relatively large percentages of applied P, Ca, and Mg were retained for longer periods. Supplementing N with lime reduced the quantity of N in the F layer, probably because of higher nitrification and volatilization rates. The L layer of the forest floor, consisting of needles that fell after fertilizers and lime were applied, more readily reflected application of P, Ca, and Mg than did intact foliage. Dominant and codominant trees responded in the second growing season to treatments containing N. The duration of the response to the relatively light rate of N lasted from 1 to 3 years. Applying lime with N produced a positive response that was still evident after the fifth growing season. Applied P had no significant effect on growth.
Third‐order Integral Relation Between Sorptivity and Soil Water Diffusivity Using Brutsaert's Technique
Authors: Parlange J.‐Y. , Braddock R. D. , Lisle I.
Published: July 2010

Integral relationships between sorptivity and weighted mean diffusivity have been usually justified by numerical tests. Optimization provides a justification on more fundamental ground, when diffusivity increases rapidly with water content. The present paper presents a further improvement on the optimization result and its precision is discussed for two general classes of soil‐water diffusivities. The result should be useful to predict soil‐water diffusivity from sorptivity measurements, especially when it can be postulated that the diffusivity has a well‐defined (e.g., exponential) functional dependence on the water content.
Saturated‐Unsaturated Flow in Radial Directions Generated by an Injection Well
Authors: Babu D. K.
Published: July 2010

The paper investigates water movement under saturated‐unsaturated flow conditions. The flows result from a vertically placed line source that injects water at a constant rate into radial directions in space. Soil water diffusivity is assumed to vary as a positive, arbitrary power of water saturation. Singular perturbation methods are applied to derive an analytical form of the solution as a power series in the perturbation parameter. The solution so concentrated is freed from singularities and breakdowns, and is therefore uniformly valid at all points of space and time. Explicit formulae are derived for the location of the wetting front as well as for the transition face between saturated and unsaturated flow regimes. Several cases of the diffusion function and injection rates are illustrated in the form of graphs. Relevance of the analysis to problems of flushing out dissolved salts from soils is briefly commented on.
Determination of Nitrate and Exchangeable Ammonium in Soil Extracts by an Ammonia Electrode
Authors: Siegel R. S.
Published: July 2010

A method for determination of NO3‐ in waters using an NH3 electrode was adapted for use with soils. Nitrate was determined in 1 N KCl soil extracts as the difference in NH3‐N concentration between aliquots treated with NaOH and Devarda's alloy to reduce NO3‐ and aliquots made alkaline without addition of Devarda's alloy. The rate of reduction of NO3‐ to NH3 was temperature dependent. The minimum recommended temperature for the procedure is 23°C. Rate of NH3 loss from solution and NH3 activity measured by the NH3 electrode increased with temperature.

Nitrate‐N in extracts of nine Illinois soils determined with the NH3 electrode was highly correlated (r2 = 0.999***)3 with NO3‐‐N analyzed by the phenoldisulfonic acid method. Exchangeable NH4+‐N determined with the modified electrode filling solution was highly correlated (r2 = 0.99***) with exchangeable NH4+‐N determined by steam distillation. In addition to NO3‐, NO2‐ is reduced to NH3 by this procedure. Recovery of added NH4+, NO3‐, and NO2‐ was 97, 97, and 91%, respectively. Precision of NO3‐ and exchangeable NH4+ determinations were 0.2 and 0.1 mg/kg, respectively. The reagents used are relatively inexpensive and safe to handle, and reduction is carried out at room temperature. Only 20 ml of soil extract is required and soils containing 1 to 250 mg NO3‐‐N/Kg can be handled routinely. One worker can analyze 80 extracts/day.
Measurement of Swelling, Hydraulic Conductivity, and Shear Strength in a Multistage Triaxial Test
Authors: Parker J. C. , Amos D. F. , Sture S.
Published: July 2010

The multistage triaxial (MST) test described here measured swelling on saturation, hydraulic conductivity, isotropically consolidated‐undrained strength, and drained and undrained compressibility. Peak strengths were evaluated by application of a hyperbolic stress‐strain model and by extrapolation of stress‐strain curves to failure. Strength parameters obtained from MST and conventional triaxial (CT) tests agreed reasonably well for three compacted soils of widely varying properties. Both drained and undrained compression modulii from MST tests increased logarithmically with increasing confining pressure. Initial undrained compression modulii from CT and MST tests agreed fairly well, although there was a definite tendency towards reduced compressibility in the later stages of MST tests. Volumetric compressibilities during the drained phases of MST tests were markedly lower than those obtained in K0 compression tests.
General Criteria for the Validity of the Buckingham‐Darcy Flow Law
Authors: Sposito Garrison
Published: July 2010

A detailed, first‐principles study is undertaken on the exact equation of linear momentum balance for water in an unsaturated soil. First, it is shown that an approximate momentum balance equation, presented originally by Raats and Klute, can be used to demonstrate unequivocably that the flow of water through a rigid, homogeneous, isotropic, unsaturated soil will obey the Buckingham‐Darcy law within 10−12 to 10−5 sec after a gradient in the total potential of soil water has been applied. Next, an exact equation of motion for the Fourier component of the water mass flux density vector is derived using standard methods in nonequilibrium statistical mechanics. This exact equation is employed to deduce the general physical criteria required for the Raats‐Klute equation to be an accurate expression. The results of the investigation lead to the conclusion that the Raats‐Klute equation will be accurate if: (i) the water mass density and mass flux density vector constitute a complete set of strongly coupled, macroscopic dynamical variables; and (ii) the time scale over which these two variables change significantly is much longer than that over which any other dynamical quantities vary. If these two conditions are met, then, according to statistical mechanics, the flow of water through unsaturated soil will be described accurately over all macroscopic time intervals by the Buckingham‐Darcy law.
Liming and Lime‐Phosphorus‐Zinc Interactions in Two Nigerian Ultisols: I. Interactions in the Soil
Authors: Friesen D. K. , Juo A. S. R. , Miller M. H.
Published: July 2010

Interactions of lime, phosphorus (P), and zinc (Zn) in two coarse‐textured Ultisols from southeastern Nigeria were examined by means of factorial soil incubation and phosphate sorption experiments.

In both soils, liming reduced exchangeable aluminum (Al) saturation from 45% to < 5% at pH 5.0 and soil solution Al concentration to < 1.0 µg/ml also near pH 5.0. There was no significant lime‐P interaction on active Al levels, indicating a lack of any ameliorating value of P on Al toxicity. Adsorption isotherms showed that liming reduced P adsorption in both soils at equilibrium solution concentrations of approximately 0.2 µg P/ml or higher, but at lower concentrations the effect became inconsistent. Soil incubation studies indicated that the concentration of P in soil solution (null‐point estimate) was first reduced by lower rates of lime then increased when soils were limed to approximately pH 6.0 or higher.

Zinc activity in soil solution declined sharply when soils were limed to pH above 5.0, but was unaffected by P applications within the pH range studied (pH 4.3 to 7.2).
Hydrodynamic Dispersion During Constant Rate Absorption of Water by Soil
Authors: Smiles D. E. , Perroux K. M. , Zegelin S. J. , Raats P. A. C.
Published: July 2010

An analysis of hydrodynamic dispersion accompanying constant flux absorption of KCl solution by an initially relatively dry soil, is developed for the case when the hydrodynamic dispersion coefficient is pore water velocity‐independent. It is shown that in this process both the water content and the soil water salt concentration are uniquely defined by θ(X,T) and C(X,T), where X = vox and T = vo2t are space and time‐like coordinates, and vo is the constant surface flux of water.

Quasi‐analytical methods based on the flux‐concentration relation predict θ(X,T) while an error‐function solution, based on a material coordinate Q labeling parcels of water, predicts the salt profile.

The analysis is demonstrated using a chemically inert sandy soil. The results show that during transient, unsaturated flow a simple piston‐flow model described the process over a range of water contents. The method may be extended to explore dispersion in structured and chemically reactive soils.
Predicting Crop Responses on High‐Potassium Soils of Frigid Temperature and Ustic Moisture Regimes
Authors: Skogley Earl O. , Haby Vincent A.
Published: July 2010

Results of 13 years of field research throughout Montana have demonstrated a relatively high rate of crop yield response to K fertilization when included in an N‐P‐K fertilizer program. Correlations between crop response to fertilizer K and ammonium acetate‐extractable K have been too low for this method to be used as a soil test. Alternative extraction methods or proposed soil test techniques were investigated in search of a useful relationship. These included saturated paste extraction, equilibrium extraction with dilute solutions, extraction with HEDTA or DTPA, ion‐exchange resin extraction, combination resin—ammonium acetate extraction, percentage‐K saturation of the CEC, and free energy of exchange relations for various ionic ratios. No adequate soil test relationship was identified in these studies.

Soils of the northern Great Plains—Intermountain region are relatively high in extractable K and have frigid (cool) temperature regimes and ustic (semi‐arid) moisture regimes. Under these conditions, chemical measurements which relate to the quantity of K in soil apparently do not have an adequate cause‐and‐effect relationship in the availability of K to plants.
Numerical Analysis of a Chronosequence, Including the Development of a Chronofunction
Authors: Sondheim M. W. , Singleton G. A. , Lavkulich L. M.
Published: July 2010

Multivariate techniques were applied to 11 chemical and physical properties of soil samples collected along a prograded beach chronosequence, located on the west coast of Vancouver Island, British Columbia. The samples were taken from three horizons at each of seven sites. The 21 samples were considered as independent observations. Application of principal component analysis with a normal varimax rotation gave highly interpretable results. The first component was readily identified with podzolic pedogenic processes, whereas the second component appeared to relate closely to sea spray input. A nonlinear optimization procedure was used to fit the first principal component to an empirical equation incorporating a logistic term for time and an exponential term for depth. A correlation coefficient value of 0.99 was obtained. The notion of a pedogenic damping depth analagous to a thermal damping depth is suggested.
Spatial Variability of Crop Yield as a Stochastic Soil Process
Authors: Bresler Eshel , Dasberg S. , Russo D. , Dagan G.
Published: July 2010

In a heterogeneous field in which the soil water properties vary, the yield of a crop may also differ from point to point. Using actual field variability data of irrigated peanut (Arachis hypogaea L.) yield, of soil water properties, and stochastic approaches, effects of spatial variability of soil water on the crop yield distribution and on the spatial correlation structures are evaluated. Values of total dry matter yield (YT) [together with two additional crop yield components pods (Yp) and hay (Yh)], soil water content [before (θb) and after (θa) irrigation], and saturated conductivity, Ks, were used to estimate distribution types (normal or lognormal) and their moments. The two‐point autocorrelation functions of YT, Yp, Yh, θa, θb, and Ks, were calculated and used to estimate their integral scales (J). The calculated J‐values for Ks, θa and θb, and YT are 25, 21, and 13 m, respectively. These results and calculations of the cross correlations between crop yield and soil water components were used to establish an approximate relationship between the crop yield and the soil water variables regarded as random spatial variables.
Effects of Skid Roads on Diameter, Height, and Volume Growth in Douglas‐fir
Authors: Wert Steve , Thomas Byron R.
Published: July 2010

This study was conducted to measure the effects of tractor logging which occurred in 1947 upon the productivity of a subsequent stand of Douglas‐fir (Pseudotsuga menziesii [Mirb] Franco) and to assess the degree and extent of residual soil compaction. The 4.33‐ha study area was categorized into skid roads, transition zones (3 m on each side of the skid roads), and undisturbed areas. Volume of every tree over 5 cm diameter breast height (dbh) was estimated by the tarif method. Forty trees in each category were measured for age‐growth relationships. Soil bulk densities were measured with a two‐probe nuclear densiometer.

Total tree volumes per hectare for skid roads, transition zones, and undisturbed areas were 34.1, 97.2, and 128.9 m3; stand densities were 693, 974, and 1,180 stems/ha, respectively. Growth reductions in the skid roads and transition zones resulted in an overall volume loss of 11.8% for the total area.

An analysis of covariance showed that there was no significant difference in the slope of the tree height‐age regression lines for each of the three categories. However, there was a highly significant difference in the adjusted height means between trees from skid road and those in the other two categories. Trees growing in the skid roads took 4.1 years longer to reach breast height than those growing in the undisturbed areas. After 32 years, 25% of the entire study area was still heavily compacted (bulk density > 1.20 g/cm3). Recovery from compaction has occurred in the surface 15 cm.
The Quantitative Assay of Minerals for Fe2+ and Fe3+ Using 1,10‐Phenanthroline: II. A Photochemical Method
Authors: Stucki J. W.
Published: July 2010

A photochemical method for measuring Fe3+ and total Fe in minerals is described. The method determines Fe2+ concentration by measuring the Fe(phen)32+ (phen = 1,10‐phenanthroline) complex formed during HF‐H2SO4 digestion of the mineral. To measure Fe2+ accurately in the presence of Fe3+ from the mineral, the sample digestion and analysis are performed under red light to prevent photochemical reduction of the ferric‐phen species. Total iron is measured by converting any Fe3+ in the digestate to Fe(phen)32+ by photochemical reduction using a fluorescent lamp. This procedure avoids the problems associated with adding chemical reducing agents to iron‐phen solutions. The calibration curves were linear up to 8‐µg Fe/ml with a lower detection limit of 0.011 µg/ml. The absorptivities of the calibration curves were 0.1852 ± 0.0017 and 0.1960 ± 0.0018 ml/cm‐µg for Fe2+ and total Fe, respectively. Ferric iron in the mineral samples was calculated by difference.