bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Sulfur Deficiency on Yield and Nitrogen Content in Bitterbrush (Purshia tridentata) Seedlings on Granitic Soils
Authors: Klemmedson J. O. , Ferguson R. B.
Published: July 2010

Previous studies by the authors have shown that addition of N (in the presence of P, K, and S) to an infertile soil derived from a granitic parent material may depress the yield of bitterbrush [Purshia tridentata (Pursh) DC.] seedlings and increase the concentration of plant N. The study presented here was conducted to determine the separate effects that added K or S would have on yield and N content of bitterbrush when applied together with N and P to the soils in question. Bioassay using both bitterbrush and barley (Hordeum vulgare L.) revealed an S deficiency in the soils that ranged from slight to strong. Bitterbrush seedlings growing on the S deficient (NPK‐treated) soils weighed significantly less than those growing on NPS‐ and NPKS‐treated soils and averaged 2.07% total N compared to only 1.15% total N for plants from all other treatments. Yield and N content of barley on the NPK‐treated soils were strongly affected only on the soil that was most deficient in available S. The results for bitterbrush were confirmed in subsequent experiments where bitterbrush was fertilized with three rates of N with and without S. In this test, the bitterbrush seedlings that received 224 kg/ha of N without S accumulated significantly more inorganic N than the seedlings that received S. Ammonium‐N accumulation was about 4.5 times higher than that of (nitrate + nitrite)‐N and was highest in roots and lowest in leaves. Reduced yield of affected seedlings may result from inhibitory effects of accumulated inorganic N or inhibition of S‐amino acid formation caused by S deficiency.
Vacuum Extractors to Assess Deep Percolation Losses and Chemical Constitutents of Soil Water
Authors: Duke H. R. , Haise H. R.
Published: July 2010

A vacuum extractor, consisting of a porous ceramic tube within a sheet‐metal trough, has been developed to provide a quantitative measure of soil water lost by deep percolation and to provide a water sample for chemical analysis. Several of these extractors have been installed in the field and preliminary field performance is reported. Detailed laboratory evaluation is in progress.
Gravity Correction Due to a Variation of Pressure Head Within a Cavity
Authors: Parlange Jean‐Yves
Published: July 2010

The infiltration of water from small cavities filled with water is affected by gravity, both within and without the cavity and these two effects are of the same order. The effect within the cavity is assessed quantitatively for small spherical cavities that are entirely or partially buried in the soil. As an example, the case of a cavity entirely buried in the soil is discussed in detail.
Kinetics of Phosphate Adsorption and Desorption by Lake Sediments
Authors: Kuo S. , Lotse E. G.
Published: July 2010

The objectives of the present investigation were to gain information on the rate and extent of phosphate adsorption and desorption and the energy of phosphate adsorption by lake sediments, and to evaluate the influence of the sediments on the phosphorus status of lake waters. While phosphate adsorption by sediments from Sebasticook Lake, Maine, could be described by the Freundlich equation over a large phosphorus concentration range, the Langmuir equation provided a good fit to the experimental data only at low phosphorus concentrations. The deviation from the Langmuir isotherm at high phosphorus concentrations was explained by an increase in total negative potential of the surface due to phosphorus adsorption and increased interaction between adsorbate molecules. The rate of phosphorus adsorption by the sediments could be described by the equation X = KC0t1/m. The calculated activation energy was 2.7 kcal/mole.

The desorption of phosphorus from minerals and sediments was dependent on the anionic species present in the solution. The replacing power of the anions appeared to be related to their ionic potential and complexing ability. The rate of phosphorus desorption could be described by the proposed kinetic equation.
Transformation of Iron in a Waterlogged Soil as Influenced by Redox Potential and pH
Authors: Gotoh S. , Patrick W. H.
Published: July 2010

The distribution of different forms of iron in a waterlogged soil was studied over a wide range of closely controlled redox potential and pH conditions. Increases in water soluble and exchangeable iron were favored by a decrease in both redox potential and pH. The critical redox potentials for iron reduction and consequent dissolution was between +300 mV and +100 mV at pH 6 and 7, and −100 mV at pH 8, while at pH 5 appreciable reduction occurred at +300 mV. The distribution between water soluble and exchangeable iron fractions was highly pH dependent with a decrease in pH at a given redox potential increasing the relative amount of ferrous iron in the soil solution at the expense of that on the exchange complex. A thermodynamic approach to the equilibria between solid phase ferric oxyhydroxide and a water soluble species of iron (Fe2+) indicated that it was largely governed by the Fe2+ − Fe(OH)3 system in which the ferric oxyhydroxide was a mixture of goethite and amorphous material.
Variation in the Natural Nitrogen‐15 Abundance in Nitrate Mineralized During Incubation of Several Illinois Soils
Authors: Feigin Amos , Kohl Daniel H. , Shearer Georgia , Commoner Barry
Published: July 2010

Samples of the surface layer of soil (0–30 cm) were collected from five sites in central Illinois. The soils were incubated under controlled conditions for an extended period of time in an effort to determine the 15N/14N ratio of the mineralizable nitrogen.

The results show that the 15N/14N ratio of the nitrate released from the soils tested was approximately constant with time of incubation after about 5 weeks. During the first weeks of incubation, the 15N/14N ratio of the nitrate released increased from an initially low value in four of the five soils tested. The constant values of δ15N (per mill enrichment) for these soils were about +7.6 to +10. We conclude that these values represent the 15N enrichment of the mineralizable pool of organic N in these soils which include major soil associations of the central Illinois Corn Belt.
Mineral Nitrogen Movement into Subsoils Following Continued Annual Fertilization for Corn
Authors: MacGregor J. M. , Blake G. R. , Evans S. D.
Published: July 2010

Two clay loam soils were fertilized for corn (Zea mays L.) at planting for 10 or 15 growing seasons at annual rates of 0, 44.8, or 268.8 kg N/ha as NH4NO3. After 10 growing seasons, little NO3‐N remained below drainage tile depth in Le Sueur clay loam. After 11 growing seasons on untiled Forman clay loam, considerable NO3‐N was found at depths to 6 or 7 meters. After 15 years, appreciable nitrate occurred to at least the 10‐m depth. The average rates of movement of the NO3 front for the 10 and the 15‐year periods were 1.7 and 1.9 mm/day, respectively. Concentrations of ammonium N were similar under all fertilizer treatments.

Annual N additions failed to significantly increase corn grain yields on Le Sueur clay loam but significantly increased yields on Forman clay loam.
A Comparison of Hydraulic Conductivities Calculated with Morphometric and Physical Methods
Authors: Bouma J. , Denning J. L.
Published: July 2010

Hydraulic conductivity of coarse porous media with packing pores could be calculated not only with accepted physical, but also with morphometric techniques if matching factors were used. Morphometric K curves were closest to physical curves derived from moisture adsorption characteristics. The morphometric technique can be applied exclusively to small or fragile homogeneous soil materials that cannot be sampled for moisture retention determinations in the laboratory. The pore interaction model of Marshall overestimated Ksat when morphometric r‐values were used. Moisture retention curves, calculated with morphometric data, agreed well in coarse porous media with physical adsorption curves.
Field Measurement of Evaporation from Soil Shrinkage Cracks
Authors: Ritchie J. T. , Adams J. E.
Published: July 2010

Weighing lysimetry was used to determine evaporative fluxes from a natural shrinkage crack and from an artificially induced soil shrinkage crack. Evaporation from the soil surface, except at the crack opening, was prevented by covering the lysimeter with plastic film. Evaporation rates from the natural and induced crack averaged about 0.6 mm/day computed on the basis of the surface area of the lysimeter. The horizontal soil water flux in the liquid phase to the crack wall was quite low, indicating that most of the measured evaporation resulted from vapor transport from some distance in the soil pores to the crack walls. Diurnal variations in evaporation rates were closely related to diurnal changes in vapor pressure deficit of the atmosphere above the soil surface. Evaporation rates from the natural/crack experiment were practically the same when the crack and soil surface were exposed to the atmosphere as when only the crack opening was exposed. Therefore, most evaporation from cracked, dry clay soil occurs because of the presence of shrinkage cracks. The results suggest a possibility for conserving water by partially filling the shrinkage cracks with dry soil or mulch to reduce evaporation. The low evaporation rates measured, however, make the feasibility of such a practice doubtful.
Loss‐on‐Ignition as an Estimate of Soil Organic Matter
Authors: Davies Brian E.
Published: July 2010

Loss‐on‐ignition at 430C of calcareous and noncalcareous soils has been compared with organic matter contents estimated by a wet oxidation method. The presence of CaCO3 did not affect the magnitude of the ignition‐loss and the gravimetric method provides both a reliable and simple estimation of soil organic matter.
Fixation of Zinc by Clay Minerals
Authors: Reddy M. R. , Perkins H. F.
Published: July 2010

Samples of bentonite, illite, and kaolinite clays were studied for their Zn fixation properties under various pH levels, alternate wetting and drying conditions, and incubation at moisture saturation. Bentonite and illite fixed significant quantities of Zn under wetting and drying. Fixation was directly related to pH and the amount of Zn added. Incubation of treated samples at moisture saturation resulted in approximately half the amount of Zn fixed as when subjected to repeated wetting and drying. Kaolinite fixed relatively small amounts of Zn as compared to bentonite and illite regardless of treatment.

Since X‐ray and DTA did not reveal mineralogical change, it is concluded that Zn was fixed as a result of precipitation, physical entrapment in clay lattice wedge zones, and/or strongly adsorbed at the exchange sites. Cation exchange capacity (CEC) values were inversely related to Zn fixation.
A Comparison of 15N‐Depleted and 15N‐Enriched Fertilizers as Tracers
Authors: Starr J. L. , Broadbent F. E. , Stout P. R.
Published: July 2010

(14NH4)2SO4 from which virtually all 15N had been removed was compared as a tracer with (NH4)2SO4 containing 8.95% 15N excess in a plant uptake experiment using soil columns maintained at ⅓ bar tension and conventional greenhouse pots. Uptake of fertilizer nitrogen in three cuttings of ryegrass (Lolium Perenne L.) was identical with the two fertilizers.

Estimates of residual fertilizer N in the pots agreed less closely, owing to the high dilution factor.
Nitrogen Transformations in Soil During Leaching: III. Nitrae Reduction in Soil Columns
Authors: Misra C. , Nielsen D. R. , Biggar J. W.
Published: July 2010

Nitrate reduction in water‐unsaturated Columbia silt loam columns was examined at 19.5C and 34.5C with three levels of oxygen (0.5, 5, and 20%) in an aerating gas passing through the soil. Following a continuous application of NH4+ solution, a pulse of a NO3‐ solution was leached through these columns. After the decay of the pulse, a continuous application of NO3‐ solution allowed mathematical analysis leading to ascertaining NO3‐ reduction rate coefficients. The temperature dependence of these constants as a function of oxygen composition was discussed and the need for microbial population and activity analysis is emphasized.
Mineralization of Carbon and Nitrogen in Soil Amended with Carbon‐13 and Nitrogen‐15 Labeled Plant Material
Authors: Broadbent F. E. , Nakashima T.
Published: July 2010

Doubly labeled barley (Hordeum vulgare L.) plants were grown in a closed chamber containing 13C‐enriched CO2 and 15N‐enriched nutrient solution. Tops and roots were separated, ground, and added to Columbia fine sandy loam in fritted glass filter tubes. Soil samples were incubated with continuous flow aeration for 5 years. Evolved CO2 was trapped for 22 weeks. Mineral nitrogen was leached from the samples at intervals throughout the 5‐year period. After 5 years, only 12% of the carbon from tops and 16% of that from roots remained in soil, compared with 38% of the nitrogen in tops and 57% of the root nitrogen. Average annual losses of carbon from soil organic matter were 6.1–6.8%; annual turnover of nitrogen varied from 6.3 to 7.4%. Availability ratios for nitrogen decreased as a function of time from about 2.5 initially to 1.2 at the end of the incubation period. Unaccounted‐for losses of nitrogen from barley tops and from soil organic matter were 15–17%, but only 2% from roots.
Recovery of Corn Yield on Gardena Subsoil as Related to Leaf and Soil Analysis
Authors: Follett R. F. , Grunes D. L. , Reichman G. A. , Carlson C. W.
Published: July 2010

Our objective was to determine the relationship of leaf N and P and soil P (NaHCO3‐soluble) in exposed subsoils to forage yield restoration resulting from fertilizer treatment. Corn (Zea mays L.) was grown on a Gardena fine sandy loam. Fertilizer treatments consisted of NH4NO3, concentrated superphosphate, and manure. Half of the plots had 30 cm of topsoil removed (cut area), the rest had no topsoil removed (undisturbed area). Cut area treatments were evaluated against corresponding undisturbed area treatments as follows
urn:x-wiley:03615995:saj2sssaj197403615995003800020032x:equation:saj2sssaj197403615995003800020032x-math-0001

A coefficient of multiple determination (R2) of 0.82 resulted when the data was fitted to the following equation
urn:x-wiley:03615995:saj2sssaj197403615995003800020032x:equation:saj2sssaj197403615995003800020032x-math-0002

If leaf N was 2.9%, 90% yield recovery was obtained when leaf P was 0.27%. A leaf N level near 2.9% or more could be obtained by the addition of inorganic fertilizer N. However, high N and P rates or N and P plus manure were required to obtain 0.27% leaf P. Leaf P values from cut areas never equalled those obtained from the corresponding undisturbed area treatment. Leaf P on the cut area was closely related to soil P only if leaf N was also considered. These results indicate that a combination of plant and soil analysis is needed to identify fertilizer requirements. The potential for restoring subsoil yields was excellent and full recovery was accomplished the first year with a combination of N, P, and manure.
On the Interaction of Water and Heat Transport in Frozen and Unfrozen Soils: II. The Liquid Phase
Authors: Groenevelt P. H. , Kay B. D.
Published: July 2010

A theory is presented for the transport in porous media of water in response to a temperature gradient and the transport of heat in response to a water pressure gradient. The fundamentals have been discussed in a previous paper. This second paper is concerned with the coupled flow processes occurring in the liquid phase. The cause of these processes is found to be the existence of the heat of wetting and the heat of fusion. Expressions for and relations between the transport coefficients are developed. Their magnitude is estimated by model calculations.
Copper (II) Interactions with Montmorillonite: Evidence from Physical Methods
Authors: McBride M. B. , Mortland M. M.
Published: July 2010

Interaction of exchangeable copper(II) with montmorillonite was studied by means of infrared and electron spin resonance spectroscopy supported by X‐ray diffraction, magnetic susceptibility measurements, and determination of CEC values. The solvation properties of the clays after heat treatment are found to be much different with ethanol than with water. Dehydration of exchangeable Cu(II) allows these ions to become imbedded in hexagonal cavities of the silicate structure, or penetrate into the empty octahedral positions and lower the layer charge. Resolvation allow the Cu(II) ions to move out of the hexagonal holes; however, Cu(II) ions that have migrated to the octahedral layer are not exchangeable. No evidence for specific adsorption was found. The results indicate that the properties of Cu(II) on clay surfaces are dependent largely on its strongly held ligand water, and the ion behaves much like other divalent ions on clays.
Fission Particle Tracks in Micas and Micaceous Vermiculites as Related to Chemical Weathering and Cation Exchange Properties
Authors: Lee S. Y. , Jackson M. L. , Sachs I. B.
Published: July 2010

Fission particle tracks from 238U impurities in natural micas and micaceous vermiculites were observed by scanning electron microscopy after hydrofluoric acid etching. Track frequency was increased by neutron activation in a thermal nuclear reactor. Without HF etching, the average rate of interlayer K+ released from micas saturated with UO22+ and activated, during 6 days depletion in 0.5N Mg(OAc)2 solutions at pH 7 renewed every few min, were 40 to 50% higher than that from nonactivated samples. Activated UO22+ saturated micaceous vermiculites from Colorado (CO) and Wisconsin (WI) liberated more K, Fe, and Si(OH)4 compared to that from the controls, in 0.5N Mg(OAc)2 at pH 4, renewed frequently. Weathering of micaceous minerals in nature would thus be accelerated by the additional diffusion of interlayer and structural cations through the natural fission particle tracks. The cation exchange capacity (CEC) of the activated micaceous vermiculites after UO22+ saturation increased from 16 to 25 meq/100g (CO) and from 6 to 12 meq/100g (WI) after the extensive salt treatments involved in CEC measurement, while negligible change in CEC occurred in the CO Na controls and one‐third as much change occurred in the WI Na control. The observed higher K+ selectivity (relative to Ca2+) of the activated samples (0.86 for CO and 1.39 for WI), compared to the controls (0.43 and 1.21, respectively), indicates that activation provided an increase in edge wedge sites for the selective adsorption of fixing cations including the fission product 137Cs+.
The Use of Radiocarbon Dating of Organic Matter in the Study of Soil Genesis
Authors: Martel Y. A. , Paul E. A.
Published: July 2010

Radiocarbon dating was used to study the nature and the stability of the organic matter in a range of Chernozemic soils (Borolls) from Saskatchewan. Two catenas, one cultivated, the other not, were studied in detail; the bottom soils of the uncultivated catena contained buried horizons.

From the crest of the knoll to the depression, the mean residence time of the surface horizon of the cultivated catena decreased from 545 years before present (B.P.) to modern, the organic matter content increased and the percentage of hydrolyzable carbon decreased. The content of organic matter decreased but the mean residence time increased by 700 to 4,000 years in the B horizons. Two buried horizons located at different depths underneath the lower members of the uncultivated catena showed mean residence times of 5,950 and 8,410 years B.P. indicating that mass movement of soil had periodically occurred since the last glaciation.

The 14C content of a field soil, measured by radiocarbon dating, was compared with the 14C distribution in fractions of another sample of the same soil after amendment with 14C‐acetate and 350 days incubation in the laboratory. The artificially labelled soil accumulated more of the tracer in the acid hydrolyzable fractions than was found by radiocarbon dating the field soil. In turn, the distribution of soil nitrogen was more closely associated with the 14C than with the unlabelled carbon of the soil.
Influence of Antecedent Soil Moisture Suction on Saturated Hydraulic Conductivity of Soils
Authors: Gerard C. J.
Published: July 2010

Studies were conducted to evaluate influences of antecedent soil moisture suction on saturated hydraulic conductivities of soils. These studies revealed that saturated hydraulic conductivity of a soil is a dynamic property which is markedly influenced by antecedent soil moisture suction. Antecedent soil moisture of ≤ 0.33 bar suction, such as is often practiced with trickle irrigation, caused marked reduction in the ability of soil to conduct water. Gases produced by microorganisms at low suction, their subsequent entrapment, and their influence on soil macrovoids are largely responsible for reduction in ability of soil to conduct water. Reduction of effective soil macrovoids by microbial growth, flowing water, and/or soil moisture suction can also reduce soil permeability. These findings indicate that soil moisture suction and management such as trickle irrigation can influence the ability of soil to conduct water.
Volatilization of Oxides of Nitrogen from Nitrate‐Treated Black Spruce Raw Humus
Authors: Mahendrappa M. K.
Published: July 2010

Raw humus sods covered with sphagnum (Sphagnum sp.) and feather (Pleurozium sp. and Hypnum sp.) mosses were treated with various forms of nitrate and then incubated in glass tanks with air passing over the sods. Oxides of nitrogen removed from the glass tanks by air were absorbed by two traps containing alkaline permanganate solution.

Volatilization of oxides of nitrogen was observed in all cases. The quantities of oxides of nitrogen evolved decreased with the treatments in the order: Al(NO3)3 > Ca(NO3)2 > NH4NO3 > KNO3. In all the treatments, the proportion of added nitratenitrogen trapped as oxides was very small (average of 0.005%). The L and F layers of raw humus became more acid with nitrate treatments.
A Simple Apparatus for Obtaining Multiple Soil Atmosphere Samples from a Single Bore Hole
Authors: Jorgensen Jacques R.
Published: July 2010

Soil atmosphere samples for analysis by gas chromatography can be obtained from reservoirs of Micro‐Por 100, a porous plastic tubing. These reservoirs have a large surface area through which diffusion can occur to obtain representative samples from specific soil areas. The apparatus is simple, low cost, and easily installed. In a loblolly pine (Pinus taeda L.) plantation, CO2 concentrates in the soil atmosphere increased from ambient at the surface to 1.2% at a depth of 60 cm.
A Two‐Phase Model for the Miscible Displacement of Reactive Solutes in Soils
Authors: Skopp J. , Warrick A. W.
Published: July 2010

Miscible displacement is studied by considering the flow regime to be composed of separate mobile and stationary phases. Solute transfer through the mobile phase occurs only by convection, whereas adsorption or reaction by the soil matrix is diffusion limited and occurs normal to the mobile‐stationary interface. The model is unique in that a specific rate law is not assumed, but the solution is exact. Results are presented graphically as a function of two parameters which are compared with experimental results of other workers. The displacement of calcium by magnesium was more closely in agreement with theoretical predictions than was adsorption of picloram.
Measurement of the Transport Coefficients for Coupled Flow of Heat and Moisture in a Medium Sand
Authors: Jury W. A. , Miller E. E.
Published: July 2010

A two‐column experiment was designed to measure the primary and cross‐coupling transport coefficients for the simultaneous flow of heat and moisture through a medium sand (Plainfield sand) in the liquid‐dominated regime of moisture flow. Values for the moisture diffusivity and thermal conductivity were obtained in the range from 20% to 90% of saturation. Thermal conductivity values fell within ± 7% of a curve calculated by the method of de Vries. In addition, the coefficient for transport of heat under gradients of moisture content was found to be zero within the accuracy of the experiment. The experiment was not sufficiently accurate to yield quantitative estimates of the coefficient for transport of moisture by temperature gradients, so a different experiment was performed to measure this coefficient indirectly. In this latter experiment the dependence of soil water potential upon temperature was found to be as much as five times larger than predicted by the surface tension model used by Philip and de Vries. These large values suggest that thermal effects should be considered for long‐term movement of soil moisture, and perhaps in certain circumstances for shorter term simulations in moist soil.
Models for Predicting Volatilization of Soil‐Incorporated Pesticides
Authors: Mayer R. , Letey J. , Farmer W. J.
Published: July 2010

In the absence of appreciable mass transfer due to water movement, diffusion processes in the soil account for the movement of pesticides to the soil surface to replace that lost by volatilization. Published solutions for heat flow equations have been applied to the volatilization of lindane and dieldrin from Gila silt loam for a number of different initial and boundary conditions. Predicted fluxes agreed well with experimental values. Five models have been proposed to describe various environmental conditions found in the field. Models I, II, and III assume pesticide concentration at the soil surface is maintained at zero concentration by air movement. Model IV assumes surface pesticide concentrations greater than zero with air turbulence sufficient to maintain zero pesticide concentration gradient in the air above the soil. Model V assumes a nonmoving air layer of various depths above the soil surface so that the pesticide concentration gradient in the air controls the rate of volatilization.
Effect of Salts and Salts Plus Nitrogen‐15‐Labeled Ammonium Chloride on Mineralization of Soil Nitrogen, Nitrification, and Immobilization
Authors: Westerman R. L. , Tucker T. C.
Published: July 2010

The effects of 0.0, 0.01, 0.1, and 1.0M concentrations of sodium, copper and calcium chloride salts added to a Pima clay loam with and without 15NH4Cl on mineralization of soil nitrogen, nitrification, and immobilization were measured over a 49‐day period. Dilute concentrations of salt, 15NH4Cl, and dilute salts plus 15NH4Cl stimulated mineralization of soil N. The “priming effect” was shown to be real and not just a simple exchange. Nitrification of native ammonium nitrogen and 15N‐labeled ammonium decreased with increasing concentrations of salt. High concentrations of copper and calcium chloride salts inhibited nitrification of 15N‐labeled ammonium more than sodium salts. Immobilization of 15NH4+‐N was decreased significantly by high concentrations of salt. Gaseous loss processes were decreased with increased salts.
Mechanism of Fire‐Induced Water Repellency in Soil
Authors: Savage S. M.
Published: July 2010

Organic soil litter collected under Manzanita (Arctostaphylos sp.) was burned over a sand column. Ottawa sand was used in the column. Temperatures were monitored by means of thermocouples in the litter layer, at the sand surface, and 1 cm deep in the sand. Two basic types of experiments were conducted. In one type the burned litter layer was allowed to remain on the sand until cool. In the other type, the burned litter layer was removed immediately after the burning period. This second type of experiment was conducted to prevent heat moving into the sand from the litter after burning. The results showed that the maximum temperatures reached in the sand, and the water repellency produced in the sand, were lower in the experiment where the burned litter layer was removed. The substances causing the water repellency in the 0 to 1‐cm depth were also more subject to extraction in the experiment where the litter layer was removed. The organic carbon content of the sand was quite similar in both experiments.

When a recently ground quartz sand was used in the sand column, the substances causing water repellency were extractable. The fractionation of the extracted substances showed that the polarity of the molecules of the substances causing water repellency decreased with depth in the sand.

Heating studies on three individual fractions indicated differences in volatility among the fractions. The chemistry of the substances in two fractions was altered by heating 20 min at 300C.

The primary conclusions of the study were that the primary movement of organic substances from the burning litter layer into the underlying sand occurs during the fire. After the burning, heat moves down through the underlying sand “fixing” some of the more polar hydrophobic substances and revolatilizing the less polar substances, thereby broadening the water‐repellent layer. The temperature required for the “fixing” and the revolatilization appears to be greater than 250C.
Water Repellent Soil Mulch for Reducing Fertilizer Nutrient Leaching: II. Variables Governing the Effectiveness of a Siliconate Spray
Authors: Snyder G. H. , Ozaki H. Y. , Hayslip N. C.
Published: July 2010

Nitrogen and potassium leaching from a fertilizer band in sand soils was reduced by creating a mulch of water repellent soil over the band using a siliconate spray. Best results were obtained using a 1% siliconate spray in quantities sufficient to penetrate about 3 cm over a region 20 cm wide, on the flat surface of raised vegetable beds. Mulches created on peaked beds were ineffective in reducing leaching, probably due to erosion of the mulch. Sweet corn (Zea mays var. rugosa) yields were comparable to those obtained by protecting N and K with plastic mulch or by applying N and K in split applications.
Reactions among Calcium Carbonate, Carbon Dioxide, and Sodium Adsorbents
Authors: Cruz‐Romero G. , Coleman N. T.
Published: July 2010

Equations for Na‐Ca ion exchange, CO2 and CaCO3 solubility and H2CO3 ionization were solved to describe and predict conditions existing in aqueous systems containing Na‐Ca adsorbent, CaCO3, CO2 and salt. Data from systems containing Dowex‐50 or hydrobiotite and having CEC‐H2O ratios approaching those occurring in soils were in reasonable agreement with the theory. For initially Na‐saturated systems, the pH varied from 7.5 at PCO2 = 0.1 atm to 10.5 at PCO2 near zero. Corresponding solution concentrations of NaHCO3·Na2CO3 were 55 and 16 meq/liter. Extremely low Ca concentrations were predicted and observed for high Na saturation and low CO2 pressure. The NaHCO3 concentration and pH varied predictably with initial Na saturation, PCO2, NaCl concentrations and relative adsorption affinity for Na and Ca. The demonstrated predictive ability may be useful in considering plant nutrition and soil reclamation problems.
Nitrogen Fixation by Blue‐Green Algae‐Lichen Crusts in the Great Basin Desert
Authors: Rychert R. C. , Skujiņš J.
Published: July 2010

Blue‐green algae‐lichen crusts (Atriplex confertifolia, Eurotia lanata, and Artemisia tridentata sites) from the Great Basin Desert have a laboratory potential of fixing atmospheric nitrogen at rates up to 84 g of N ha‐1 hour‐1. Nitrogen fixation is optimal when the crust is moistened to ‐⅓ bar pressure, temperature is 19 to 23C, and the light intensity is 200 microeinsteins m‐2 sec‐1 with incandescent light. The acetylene reduction technique provided a useful assay to measure in situ nitrogen fixation which was correlated with potential values obtained in the laboratory under optimum conditions. Nitrogen fixation was found to be reduced under desert shrub canopies possibly due to allelopathic effects of the shrubs. Aqueous leaf extracts of desert shrubs significantly inhibited nitrogen fixation. Annual nitrogen fixed was estimated at 10 to 100 kg of N ha‐1 year‐1, depending upon microenvironmental conditions.
Residual Availability of Fertilizer Zinc
Authors: Boawn Louis C.
Published: July 2010

Residual availability of fertilizer Zn was measured over a period of 5 years. Three variables were evaluated: Zn rate, free carbonates, and wheat straw residue. Zinc was applied at 0, 5.6, 11.2, 16.8, and 22.4 kg Zn/ha as ZnSO4 · H2O to a noncalcareous soil and a subsoil containing 4.3% lime. The residue variable was imposed by making three annual applications of wheat straw of 11.2 metric tons/ha. Measurements were made annually for extractable soil Zn and the utilization of Zn by sweet corn (Zea mays L., ‘Golden Cross Bantam’ hybrid).

Percentagewise, conversion of fertilizer Zn to forms unextractable with 0.005M DTPA solution or 0.1N HCl was comparable for all rates of Zn application. There was a relatively rapid conversion of Zn to nonextractable forms during the first year, followed by a declining rate during the second and third year. The percentage of Zn extractable was essentially unchanged during the fourth and fifth years. At equilibrium, 85 to 90% of the fertilizer Zn was unextractable with 0.005M DTPA. In terms of a desirable Zn soil test of at least 0.8 ppm, a Zn application of 5.6 kg/ha was adequate for not more than 2 years, whereas 11.2 kg/ha was satisfactory for about 4 years. Neither extractable Zn nor Zn uptake by sweet corn indicated an adverse effect of free carbonates on residual availability. The effect of straw residue on residual availability of Zn was too minor to have significance in terms of fertilization practices.
Soil Classification and Land Sale Prices
Authors: Westin F. C.
Published: July 2010

Over 4,800 verified land sales in South Dakota covering a period of 1967–1972 were located on the South Dakota Soil Association Map (scale 1:500,000). The first‐named soil in the association was classified in the U. S. Comprehensive Soil Classification System as to order, suborder, great group, subgroup, and family and related to the average price paid per acre. Using coefficient of variation as a measure of homogeneity of a classification category, the most homogeneous units in South Dakota at each level of classification are: Mollisols, Borolls, Haploborolls, Glossic Natrustolls, and Typic Argiustolls, fine, mixed, mesic. In general not all units at the same categorical level are defined with the same precision, but climatically defined units were more homogeneous. In comparing categories, two of seven suborders were more homogeneous than the most homogeneous order, three of ten great groups were more homogeneous than the most homogeneous suborder, nine of twenty‐seven subgroups were more homogeneous than the most homogeneous great group and two of thirty‐seven families were more homogeneous than the most homogeneous subgroup. Some precision was gained at each level, with the greatest gain in homogeneity appearing between order and suborder and the least between subgroup and family.
Calcite and Dolomite as Developmental Criteria in Young Soil Derived From Dolomitic Materials
Authors: Raad A. T. , Protz R.
Published: July 2010

Genetic development of five weakly‐developed soils derived from dolomitic materials on five different glaciofluvial landforms was measured using indices. A calcite‐leaching index was calculated from the maximum calcite percentage below the solum/calcite percentage in soil horizons, and a dolomite‐weathering index to measure the degree of dolomite weathering was calculated from the dolomite content at the bottom of the solum/dolomite content in soil horizons. Both indices could be successfully used to measure genetic development of the five soils.
Physical and Chemical Properties of Soil Associated with Heavy Applications of Manure from Cattle Feedlots
Authors: Tiarks A. E. , Mazurak A. P. , Chesnin Leon
Published: July 2010

Cattle feedlot manure at 0, 90, 180, or 360 metric tons ha‐1 year‐1 was incorporated with Sharpsburg silty clay loam to depths of 10, 20, and 30 cm. For plots tilled 10‐cm deep, the heaviest applications increased the soil organic carbon content from 2 to 5% after 2 years. Particle density decreased from 2.63 to 2.50 g cm‐3 and bulk density decreased from 1.05 to 0.90 g cm‐3. Geometric mean diameter of water‐stable aggregates increased from 80 to 800 µm. Modulus of rupture of soil cores decreased from 0.60 to 0.08 bars. Hydraulic conductivity of undisturbed soil cores increased five fold. Manure applications reduced the hydraulic conductivity of disturbed soils sampled in the fall, but there was no effect on spring samples. The heaviest application of manure increased the electrical conductivity of the hydraulic conductivity leachates from 0.8 to 3.2 mmhos cm‐1 in the fall samples and from 0.4 to 1.2 mmhos cm‐1 in the spring samples. The effects of manure on soil properties decreased with increased depth of tillage.
Scanning Electron Microscopic and X‐ray Diffraction Study of Natural Weathering of Phlogopite Through Vermiculite to Saponite
Authors: Jackson M. L. , Sridhar K.
Published: July 2010

The weathering of phlogopite mica through vermiculite to saponite was demonstrated by X‐ray diffraction (XRD), quantitative mineralogical analysis and electronoscopic studies. The sand grain sized flakes showed highly crystalline (high intensities at 10Å with K saturation) minerals with a high degree of interstratification of mica‐vermiculite (12.4Å) and mica‐saponite (27.5Å) as well as discrete mica (10Å), vermiculite (14.9Å), and saponite (19.2Å) phases with Mg saturation and glycerol solvation. The saponite increased from 48% in the coarse clay to 70 to 72% in the fine and medium clay, while vermiculite decreased from 34% in the coarse clay to 12 to 17% in the fine and medium clay fractions. Scanning electron microscopy (SEM) of Li+‐saturated, electrical double‐layer‐swollen, freeze‐dried macroflakes of phlogopite revealed that saponite layers glided out from interstratified sites within the mica and folded at the mica‐vermiculite grain boundary. Authigenic mica needles were observed at some flake margins. A visual model of the formation of the expansible phyllosilicate clays, vermiculite and saponite, from mica is provided. Significant amounts of 137Cs+ fixation and 90Sr2+ trapping is to be expected in such systems.
A Simple, Inexpensive Apparatus for Simultaneous Collection of CO2 Evolved from Numerous Soils
Authors: Weaver R. W.
Published: July 2010

An apparatus was constructed from polyvinylchloride pipe and 30‐gauge disposable hypodermic needles for measurement of microbial activity in soil. The apparatus was compact, easy to construct, and adaptable to any number of samples. It has been used in our laboratory for simultaneous collection of CO2 from 250 soil samples.
Two‐Dimensional Water Infiltration from a Trench in Unsaturated Soils
Authors: Sawhney B. L. , Parlange J.‐Y.
Published: July 2010

Two‐dimensional infiltration of water from finite trenches was observed in three soil samples with different textures. The vertical infiltration is slowed by the lateral infiltration and the slowing is inversely proportional to the width of the trench. Furthermore, the vertical infiltration is about twice as fast as the lateral infiltration for all soils tesed. At the same relative distance from the trench, the soil was drier beside than below the trench. Our observations and interpretations agree with numerical simulations of Selim and Kirkham.
Limitations of the Instantaneous Profile Method for Field Measurement of Unsaturated Hydraulic Conductivity
Authors: Baker F. G. , Veneman P. L. M. , Bouma J.
Published: July 2010

Technical problems and soil profile characteristics may limit the applicability of the instantaneous profile method for field measurement of unsaturated hydraulic conductivities. A modified procedure for tensiometer installation and different methods for measuring moisture contents are discussed. Good agreement was found between moisture contents determined in situ with the neutron‐probe and those indirectly derived from moisture retention curves obtained from measurements of large core samples in a closed assembly. Sloping soils with slowly permeable horizons or with lateral water movement cannot be characterized adequately with this method. The use of the crust test procedure is recommended.
Growth, Mineral Composition and Seed Characteristics of Sesame as Affected by Nitrogen, Phosphorus, and Potassium Nutrition
Authors: Mitchell G. A. , Bingham F. T. , Yermanos D. M.
Published: July 2010

Sesame (Sesamum indicum L.) was grown to full maturity in three sand culture experiments with variable rates of N, P, and K. Tissue samples of the most recently matured leaves were taken at three stages of growth for chemical analysis and correlation with optimum yield and quality of the seed. Nutrient response curves were obtained along with approximate critical concentrations of N. P, and K.

Samples taken at early flowering stage appeared to be best suited for use in establishing diagnostic criteria for the fertility requirements of sesame. The approximate critical concentrations of leaf NO3‐N, total P, and K were 0.51%, 0.52% and 2.4%, respectively.

Increasing substrate levels of N, P, and K resulted in increases in all components of yield, while effects on seed quality were mixed. Increased levels of substrate N resulted in increased protein and decreased oil content. Potassium demonstrated a similar, although smaller, increase in protein and corresponding decrease in oil content. Phosphorus alone had no effect on protein or oil content.
A Leak‐Proof Sampling Port in Gas Analyses Studies
Authors: Smid A. E. , Beauchamp E. G.
Published: July 2010

Unmodified rubber serum caps frequently used as sampling ports in gas analysis studies, failed to reseal after being punctured. Mean N2 leakage through puncture holes increased from 92 to 5,200 µliters/liter after 24 hours with one puncture and to 12,000 µliters/liter after an additional 24 hours with two puncture holes. Leak‐proof serum caps were devised by sealing silicone rubber septa into them with silicone rubber sealant.
Convergence and Validity of Time Expansion Solutions: A Comparison to Exact and Approximate Solutions
Authors: Parlange Jean‐Yves
Published: July 2010

The convergence of series solutions for the diffusion equation by time expansion is discussed quantitatively, on the basis of the linear and delta function solutions for a spherical cavity. It is shown that convergence alone is a poor criterion to justify the validity of the series solutions. A counter example, diffusion in the presence of an impervious wall, shows that the series may converge for all times but be entirely erroneous. By comparison an approximate integral technique yields a solution which agrees very well with the exact result.
Movement of Two Nonionic Surfactants in Wettable and Water‐Repellent Soils
Authors: Miller W. W. , Valoras N. , Letey J.
Published: July 2010

The movement of two nonionic surfactants (Soil Penetrant 3685, Aqua Gro) and their effect on water flow through wettable and water repellent soils was investigated. Surfactant concentrations of 0, 100, 500, 1,000, 1,600, and 3,200 ppm were applied to the top of vertical soil columns and the concentration of surfactant in the column effluent was measured. When the concentration of surfactant in the effluent did not significantly change with time, leaching of the columns with tap water was initiated. Both surfactants affected the hydraulic conductivity of the hydrophobic soil. The conductivity effects appeared to be related to aggregate destabilization, micelle formation, and particle migration, all of which caused a general decrease of flow rates with time. Adsorptive characteristics were found to affect greatly the shape of the effluent concentration versus time curve. Aqua Gro was shown to be more strongly adsorbed and less subject to leaching than was Soil Penetrant. A theoretical model was tested for its ability to qualitatively predict experimental effluent concentrations. Allowing for the spreading effects of dispersion, there was reasonable agreement between most experimental and theoretical values. The behavior and movement of surfactants in soils are a function of adsorption isotherms, mixing or dispersion due to flow velocities, solute concentration, and the physical and chemical characteristics of the porous medium.
Influence of Soil Microstructure on Water Characteristics of Selected Hawaiian Soils
Authors: Tsuji G. Y. , Watanabe R. T. , Sakai W. S.
Published: July 2010

The higher water‐holding capacity of Oxisols and Ultisols compared to that of the Vertisols and Inceptisols at 15 bars of suction is attributed to the presence of intra‐aggregate void spaces. Existence of such voids was verified with the aid of a scanning electron microscope. These voids are obvious in soils with kaolinitic and oxidic mineralogy but are not evident in soils of montmorillonitic or amorphous oxide composition.
Effect of Stones on the Hydraulic Conductivity of Relatively Dry Desert Soils
Authors: Mehuys G. R. , Stolzy L. H. , Letey J. , Weeks L. V.
Published: July 2010

The objective of this study was to determine whether moisture transmission properties of stony soils could be evaluated using samples of the same soil in which the stony fraction (> 2 mm) had been excluded. Experiments were conducted in the laboratory on soil columns with and without stones. Unsaturated hydraulic conductivity (K) was measured with a transient outflow method over the matric potential range of −0.05 to −50 bars using tensiometers and soil psychrometers. The soils studied were Rock Valley gravelly loamy sand (Mojave Desert, Nevada) and Tubac and Rillito gravelly sandy loams (Sonoran Desert, Arizona). On a weight basis, these soils contain up to 40% stones > 2 mm in diameter.

If expressed as a function of matric potential, hydraulic conductivity values were similar, with or without stones. Soil water potential as measured by tensiometers or by thermocouple psychrometers is not affected by stones because these instruments respond to moisture changes in the soil portion only. When K was expressed as a function of volumetric water content, the apparent conductivities were higher for a given water content when stones were present. A simple correction of water contents of stone‐free samples, based on the stone volume of each soil, adequately accounted for differenecs observed when water contents were computed on a total volume basis.
Sulfur Fractions and Carbon‐Nitrogen‐Phosphorus‐Sulfur Relationships in Some Brazilian and Iowa Soils
Authors: Neptune A. M. L. , Tabatabai M. A. , Hanway J. J.
Published: July 2010

Current knowledge concerning the percentage distribution of the various S fractions in soils is mainly derived from studies of S in surface soils of temperate regions. This study was conducted to determine the S fractions and C‐N‐P‐S relationships in some subtropical soils from Brazil and to compare the values in these soils with those in soils of a temperate region from Iowa.

Analyses for S fractions in some Brazilian and Iowa surface soils indicated that, unlike Iowa soils, Brazilian soils contain adsorbed inorganic sulfate S. Expressed as percentage of total S in soils, the Brazilian soils studied contained from 5 to 23% inorganic sulfate S, from 20 to 65% ester sulfate S, from 5 to 12% C‐bonded S, and from 24 to 59% unidentified organic S. The corresponding percentages in the Iowa soils were: from 2 to 8% inorganic sulfate S, from 43 to 60% ester sulfate S, from 7 to 18% C‐bonded S, and from 31 to 39% unidentified organic S. No inorganic nonsulfate S could be detected in any of the Brazilian and Iowa soils analyzed.

Tests showed that the Brazilian soils studied have capacities for adsorption of sulfate S. There were considerable variations in C, N, P, and S relationships among the Brazilian soils as compared with those among Iowa soils.