bluuebunny/crossref_metadata_2025 huggingface dataset:
Nutrient Relationships Between Soils and Needles of Loblolly Pine (Pinus taeda)
Authors: Wells C. G.
Published: July 2010

Highly significant correlations were found between nutrients in the soil and needle content of 5‐year‐old loblolly pine for all seasons and needle age classes. Mineralized N was more highly correlated with percentage N in the needle than was total N. Available P by the Truog and Bray no. 2 methods was more closely related to percentage P in the needles than was total P. Percentage exchange capacity saturated with K accounted for more of the variability in percentage K in the needles than did either exchangeable K or acid‐extracted K. Exchangeable Ca and Mg were more closely related to percentages of these elements in the needles than was percentage saturation with these elements. Antagonism interactions were indicated between K and Ca or Mg but not between Ca and Mg. Needle samples of the previous year's first growth flush collected in late winter from the upper crown were best for relating nutrient content of needles to soil fertility.
Phosphate Fractions in Some Texas Grumusols and Their Relation to Soil Weathering and Available Phosphorus
Authors: Hawkins R. H. , Kunze G. W.
Published: July 2010

The phosphate fractions were determined in nine profiles of Grumusols from Texas, representing four soil series. Soil weathering and available P were shown to be related to certain of these fractions.

The distribution percentages for Ca‐P, Al‐P, and Fe‐P serve as sensitive indicators of the weathering environment. These show Beaumont clay to be the most weathered and Victoria and Houston Black clay to be the least and about equally weathered. Lake Charles clay occupies an intermediate position, through none of the four have undergone much weathering.

Free salts, particularly soluble sulfate salts, were found to affect the distribution percentages of Ca‐P and Al‐P in the Victoria profiles.

Available P was correlated with Al‐P in all but the Victoria profiles where Ca‐P was correlated with available P. Indications are that the correlations between Al‐P and available P are fortuitous and more realistically reflect small amounts of mineralized organic phosphates extracted by the initial extraction for Al‐P.

The C/P ratios of the organic matter in the A horizons of the Grumusols range from 27 to 295. The higher ratios are associated with the Beaumont and Lake Charles soils, whereas the majority of the values for the A horizons of Victoria and Houston Black soils are below 75. The lack of response to applied P on these soils is attributed to the large amounts of organic P and accompanying low C/P ratios. Decomposition of organic matter in these soils results in mineralization of significant amounts of organic phosphates which are then available for use by the plant.
Effect of Liming and Flooding on Manganese Toxicity in Alfalfa
Authors: Graven E. H. , Attoe O. J. , Smith Dale
Published: July 2010

Incubation and greenhouse studies showed that regardless of soil pH, flooding increased the content of exchangeable Mn and the Mn content of alfalfa (Medicago sativa L.) grown in a Kellner loamy sand. In the absence of a source of easily decomposable organic matter, Mn mobilization by flooding was considerably slower at a soil pH of 4.7 than at 7.3. Where alfalfa was grown in the soil or where finely milled oat straw was added, flooding mobilized more Mn in the acid than in the neutral soils. Liming promoted immobilization of Mn on the resumption of normal soil moisture relations after flooding. Seventy‐two hours of flooding increased the Mn content of the alfalfa on the unlimed soil from 426 ppm to more than 6,000 ppm. Excess Mn tended to accumulate in the leaves and growing points of the plants. The results suggest that the well‐known susceptibility of alfalfa to Mn toxicity may also account for its sensitivity to poorly aerated soils.
Multiple Working Hypothesis in Soil Genesis
Authors: Arnold R. W.
Published: July 2010

Current theories of soil genesis emphasize variable rates of processes in the differentiation of soils, and include the implication that soils of similar morphology may have travelled different pathways. Multiple hypotheses, proposed as explanations of observed soil features, may be expressed as sequential models, each depicting an alternate mode of development.

The genesis of neo‐skeletans in subsoils of some Udolls is examined in four models. Soil morphology, empirically related to different environmental conditions (state factors), is interpreted as the consequence of a combination of variable rate genetic processes. It is concluded that polygenesis is likely involved in the development, maintenance, and/or preservation of neo‐skeletans in Udoll subsoils. Regardless of the genetic pathway, the resulting soils are believed to be youthful entities within a genetic spectrum whose striking morphological features have been dominantly influenced by translocations of inherited clay.
An Evaluation of Imipramine Hydrochloride as a Reagent for the Quantitative Determination of Nitrate in Plant Material and Soil Extracts
Authors: Simpson Elmer C. , Barrows Harold L.
Published: July 2010

A qualitative determination for nitrates was investigated for possible use as a rapid, routine, quantitative, colorimetric procedure for nitrates in soil extracts and plant material. The inherent difficulties and the limitations of the procedure are shown and discussed.
Phosphate—Ammonium—Moisture Relationships in Soils: II. Ion Concentrations in Leached Fertilizer Zones and Effects on Plants
Authors: Blanchar R. W. , Caldwell A. C.
Published: July 2010

Radioactive fertilizer pellets MCP32, MCP32 + NH4Cl, and MCP32 + KCl were placed in a Dakota sandy loam and allowed to react for 2 weeks. The pots containing the fertilizer were then leached with 0, 2, 4, and 8 cm of water. Corn (Zea mays) was grown on these pots for 2 weeks and analyzed for total and radioactive P. Results showed only trace amounts of fertilizer P taken up from all nonleached pots. Leaching the pots with 2 or more centimeter of water resulted in a significant uptake of fertilizer P. When the pots were leached with 4 cm of water, P uptake from MCP + NH4Cl pellets was nearly 3‐fold that of either MCP or MCP + KCl. Measurement of water‐soluble P and other conditions in the fertilizer zone indicated no differences between MCP + NH4Cl and MCP + KCl pellet zones. It was concluded that ammonium increased the capacity of the plant to absorb P and did not affect the availability of P in the soil.
A Computer Technique for Prediction of CaCO3 Precipitation in HCO3‐ Salt Solutions
Authors: Tanji K. K. , Doneen L. D.
Published: July 2010

Five salt solution systems containing HCO3‐ were concentrated by evaporation, in contact with laboratory atmosphere, to simulate 2‐to 10‐fold reduction in volume. The amounts of CaCO3 precipitated, final pH, and final solute concentrations were comprehensively predicted from the initial solute concentrations, degree of concentration of initial solution volume, and final PCO2. A flow diagram of the computational scheme is presented for IBM 7040 Data Processing System. The basic equilibrium relationships in the CaCO3 and HCO3‐‐CO32‐ cycles are applicable to any aqueous systems which precipitate CaCO3 due to changes in solute concentration, partial pressure of CO2 or ambient temperature.
Elutriator for Fractionating Silt
Authors: Beavers A. H. , Jones Robert L.
Published: July 2010

A modification of the Kopecky elutriator involving mode of sample introduction and transfer of suspended particles between elutriator tubes is described. Results of routine application demonstrate its efficiency in separating particulate material into size fractions and its economy of time.
A Soil Salinity Sensor of Improved Design
Authors: Richards L. A.
Published: July 2010

Kemper (1959) showed that an electrical conductivity cell with spaced electrodes in fine‐pored ceramic that is in contact with the film water in soil can provide continuous measurement of the salt concentration of the soil solution. Information is given on an improved sensor of this type. The response time has been reduced to about 1 hour for bulk solutions by using a ceramic plate 1 mm thick for the sensitive element. The effect of external current paths has been eliminated by shielding and insulation, and temperature compensation has been added. Information is given on calibration procedure, along with data on the use of the senor in irrigation tests and the relation of such data to leaching‐requirement theory.
Plant Availability and Form of Residual Phosphorus in Davidson Clay Loam
Authors: Singh R. N. , Martens D. C. , Obenshain S. S.
Published: July 2010

The form and availability of residual P in Davidson clay loam, a Reddish Brown Lateritic soil, was investigated. Various levels of residual P had been established in the soil by annual application of superphosphate for 17 years. In a greenhouse experiment, residual P from annual application of 21 lb P/acre was adequate to supply the P requirement of three successive crops of alfalfa (Medicago sativa L. ‘DuPuits’); application of 10.5 lb P/acre was inadequate. Phosphorus fractionation by the Chang and Jackson procedure (5) showed that native and residual P was present in the soil predominantly as iron phosphate; application of superphosphate resulted in small but significant increases in aluminum and calcium phosphates. A comparison of the inorganic fractions in soil before and after growth of the three crops of alfalfa provided evidence that aluminum, iron, and calcium phosphates were sources of P to the first crop and that iron phosphate was the main source to the second and third crops. The availability of the three fractions was explained on the basis of their composition and soil pH and exchangeable Ca2+ content.
Soil Properties Affecting Dieldrin Toxicity to Drosophila melanogaster
Authors: Hermanson H. P. , Forbes Clifford
Published: July 2010

The toxicity to Drosophila melanogaster Meigen of dieldrintreated soils was measured by bioassay. Under adequate standardization and control of light, temperature, humidity, and soil moisture, the variation in insecticidal activity was closely related to the colloidal properties of the soils. As organic carbon content, specific surface area of the minerals, and soil reaction increase, higher levels of dieldrin were required to maintain the killing power. Cation‐exchange capacity interacts with soil organic carbon content to increase dieldrin effectiveness. The dieldrin activity equation developed shows that often the simplest practical mathematic model of soil pesticide activity should be quadratic.
Neutron Activation Products from Project Sedan in Plants and Soils
Authors: Romney E. M. , Rhoads W. A.
Published: July 2010

Neutron activation products of tungsten, scandium, and antimony were among those radionuclides concentrated through roots of plants grown on ejecta from the Sedan thermonuclear cratering detonation. Nuclear reactor‐produced isotopes were used in corroborative experiments to investigate, in greater detail, their behavior in plants and soils. Radiotantalum was also included as a matter of academic interest.

Plants concentrated more Sc46, Sb124, and W185 in leaves than in stems, whereas Ta182 was concentrated more in stems. Plant uptake of Sc46, Sb124, and W185 was Influenced by different types of soil. Scandium‐46 and Ta182 were virtually immobile in columns of soil leached with 76 cm of water while Sb124 and W186 moved readily in neutral and alkaline soil, but not in acidic soil. Their behavior was influenced by the kind of clay mineral present, the sodium and potassium content, and the soil pH.
Soil Moisture Characteristics of Sand‐Peat Mixes
Authors: Juncker Paul H. , Madison John J.
Published: July 2010

Mixtures of Osoflaco sand and screened Canadian peat were examined for bulk density, tension‐moisture relations, wilting tensions and readily available water. As peat content increased, mixtures became lighter (less dense), held more available water, had a lower zone of saturation and approached wilting tensions more gradually. Tension‐moisture curves indicate relatively uniform pore sizes in the sand, but a relatively wide distribution of pore size in the peat.
Molybdate Phase Equilibria in Soil
Authors: Follett R. F. , Barber S. A.
Published: July 2010

Solubility product relationships were investigated as a means of determining the possible solid phase forms of Mo which govern the concentration of Mo in the solution phase of soils. The Ksp value for ferrimolybdite was not available in the literature and was estimated to be approximately 10‐52.

The activities of Ca, Fe, Mo, and H in the liquid phase after 24 leachings and CaO treatments were used to determine possible solid phase forms in a Maumee sandy loam soil. Calcium molybdate and ferrous molybdate were too soluble for their solid phases to exist in this soil.
Water Flow in an Unsaturated Soil with a Step‐Type Initial Water Content Distribution
Authors: Jensen R. D. , Klute A.
Published: July 2010

Water flow against the water content gradient in soil columns composed of two layers of a given soil, with the upper layer at a higher water content than the lower layer, has been reported in the literature. From experiments with columns involving air gaps, control and variation of the temperature gradient, removal of water by evaporation, porous membranes and air‐dry soil, water content and pressure head measurements, it was concluded that vapor movement was the dominant mechanism when water was removed by evaporation. A vapor pressure gradient, originating from the temperature gradient created by the evaporation of water from the soil, provided the driving force for vapor transfer against the water content gradient. Liquid transfer predominated when water was removed isothermally. Initially water moved from the wetter layer into the drier soil in response to the pressure head gradient. After a time, the direction of the pressure head gradient reversed without a corresponding reversal in the water content gradient and water flowed out of the drier soil against the water content gradient.

Two phenomena were instrumental in reversing the pressure head gradient. First, disturbance of the soil during the handling procedures caused an increase in the pressure head without a change in the water content. Second, since the driver layer initially gained water and dried thereafter, hysteresis also reduced the pressure head difference between the soil layers. Then removal of only a small quantity of water from the wetter soil made the pressure head smaller in the wetter soil than in the drier layer and the direction of the pressure head gradient reversed.
Interstratification in Vermiculite and Biotite Produced by Potassium Sorption: II. Evaluation by One‐Dimensional Fourier Analysis
Authors: Rhoades J. D. , Coleman N. T.
Published: July 2010

The one‐dimensional Fourier analysis was applied to the determination of the distribution of sorbed potassium in initially magnesium‐ or sodium‐saturated South African vermiculite and Bancroft biotite. It was concluded that while the type of interstratification produced through K sorption by vermiculite was not entirely regular, there was a definite trend in that direction. The biotite sample, on the other hand, apparently underwent zonal segregation upon K sorption when the complementary cation was Mg, whereas random interstratification seemed to be the case for the analogous Na system. Difficulties encountered in the use of this approach were discussed in terms of “skewness” and obscuration of X‐ray diffraction peaks and the apparent intermixing of interstratification types obtained. Information gained from the Fourier analysis was used to speculate on reasons for the observed distribution of K in the materials.
Nitrogen Losses from Urea as Affected by Altering Soil Urease Activity
Authors: Moe P. G.
Published: July 2010

Laboratory incubation experiments were conducted to determine whether nitrogen losses from urea could be reduced by manipulating the urease activity of the soil. The natural urease activity of Chalmers silt loam and Plainfield sand was modified directly by applications of either additional urease enzyme or an enzyme inhibitor and indirectly by applications of a decomposing mulch and liming material. Additional urease enzyme increased the rate of urea hydrolysis, the rate of ammonia volatilization during the early part of the incubation period, and also the rate of nitrification during the latter part of the incubation period. The enzyme inhibitor, p‐chloromercuribenzoate, decreased the rate of urea hydrolysis but maintained soil ammonium contents at a high level throughout the entire incubation period due to inhibition of nitrification. Treatments had no significant effect on total volatile ammonia losses.

The presence of a corn mulch layer (Zea mays) in the zone of urea application increased urea hydrolysis rates only when the mulch was undergoing rapid decomposition. The mulch layer increased initial rates of ammonia volatilization but reduced leaching losses of nitrogen significantly. Significantly lower volatile ammonia losses were observed when lime and urea were applied together on the surface of a corn mulch than when they were applied to bare soil.
A Tracer Study of Nitrogen Balance and Residual Nitrogen Availability with 12 Soils
Authors: Legg J. O. , Allison F. E.
Published: July 2010

Plantavailability of 15N‐tagged residual N following oats (Avena sativa L.) fertilized with 50, 100, or 200 ppm N was studied under conditions offering maximum exploitation of the tracer N. These conditions were achieved by subsequent uniform additions of nontagged N, as well as other nutrient elements, to promote good plant growth. Total recovery of tracer N in the initial oat crop and two succeeding crops of sudangrass (Sorghum sudanensis), plus that remaining in the soil, averaged 94% for all soils and treatments, but ranged as low as 82% for the low N treatment of the Fargo soil. On most soils the percent total recovery was not influenced greatly by N rates. Tracer N remaining in the soils after cropping ranged from 10 to 36% of the original addition and decreased with increasing N rate.

Residual N uptake by the first cutting of sudangrass, as a percentage of the tracer N which was not removed by the previous crop, ranged from 10 to 41% and generally increased with rate. Availability of the residual N to the second cutting of sudangrass dropped to an average of 4.5% of the remaining tracer N, with few significant differences among soils or treatments. Retention and availability of residual N were related to the relative N‐supplying capacities of the soils.
Modified Tube Diameters for the Double‐Tube Apparatus
Authors: Bouwer Herman , Rice R. C.
Published: July 2010

Experiences with the double‐tube method indicated that the diameter of the outer tube should be larger than the theoretical minimum because of soil disturbance in the annular space between the inner and the outer tube. Field studies were conducted in Adelanto loam and in river sand using outer tubes of various diameters in combination with an inner tube with a constant diameter. The results indicated that, for an inner‐tube diameter of 12.7 cm, an outer‐tube diameter of 25.4 cm was sufficient to eliminate most of the effects of soil disturbance in the measured value of the hydraulic conductivity. Values of 10.2 cm and 20.3 cm for the diameters of the inner and outer tubes, respectively, also appeared to be satisfactory.
Negative Adsorption by Vermiculite: Salt Exclusion from Interlayer Volumes
Authors: El‐Swaify Samir , Coleman N. T. , Bredell G. , Arca M.
Published: July 2010

For vermiculite immersed in NaCl or CaCl2 solutions, the amount of water that excluded Cl was 0.22 g/g and was not affected appreciably by the electrolyte concentration or the particle size of the mineral. The measured exclusion volume corresponds to the interlayer volume calculated from the c‐axis spacing and an assumed specific surface of 750 m2/g. The results suggest that vermiculite in aqueous solutions should be regarded as having two distinct and clearly separated ionic regions—the interlayer spaces containing exchangeable cations and water but not soluble electrolyte, and the interparticle solution.
Shallow‐Water Impoundment Increases Soil Moisture and Growth of Hardwoods
Authors: Broadfoot W. M.
Published: July 2010

Soil moisture during the growing season and radial tree growth were significantly increased by impounding winter and spring rainfall until July 1 on hardwood sites in the Mississippi Delta. In early July, the average moisture per 30 cm of soil amounted to 19.5 cm for the area that had been flooded and 13 cm for the control soil. Even late in the growing season, soil in the impoundment contained about 1 cm more moisture. Timber growth was increased by about 50%. Oxygen in the water was depleted after 15 days of dry weather, but was quickly replenished by rain.
Heats of Immersion Studies on Anion‐Treated Ferric Oxide
Authors: Jurinak J. J. , Burau R. G.
Published: July 2010

Microcalorimetry was used to obtain heats of immersion data for αFe2O3 (hematite) treated with SO4‐2, H2PO4‐1 or MoO4‐2 at pH 4.0. The data were compared with values from a reference OH saturated iron oxide. Using water adsorption data, the net integral heats of adsorption as functions of outgassing temperature (25 to 470C) were calculated. The energies of adhesion were also determined. Anion penetration lowered the surface energy of hematite, as manifested by a lowering of the immersional heats with increasing outgassing temperature. At pH 4.0 the relative bonding strengths of the anions on hematite were concluded to be MoO4‐2 > H2PO4‐1 > SO4‐2 > OH‐1. The heat of immersion values after 25C outgassing indicated limited anion effect as well as a physical interaction of water with αFe2O3. The molybdate ion had the greatest effect on surface energy at all outgassing temperatures.

The energy of rehydration (hydroxylation) of the αFe2O3 surface was also calculated from the data.
Nitrogen Effects on Cotton: I. Vegetative and Fruiting Characteristics
Authors: Gardner B. R. , Tucker T. C.
Published: July 2010

A series of N fertilization experiments was conducted over three growing seasons, at three elevations, utilizing two varieties of ‘Acala’ cotton (Gossypium hirsutum) on two soil types. The treatments consisted of various rates and timing of N fertilizer applications. Data indicated that N deficiency at early growth stages limited development of vegetative branches, internode elongation, and fruiting, particularly in “one‐peak” flowering areas. Cotton plants can compensate by increased fruiting in longer seasons or “two‐peak” flowering areas when adequate N is available during late season following earlier N deficiency. The effect of N applications on fruiting and yield was dependent on the intial N fertility of the soil and the yield possibility. When N was limited, yield and fruiting were increased by N applications. Petiole analyses were used to show the relationship between N nutrition and yield and fruiting.
Nitrogen Effects on Cotton: II. Soil and Petiole Analyses
Authors: Gardner B. R. , Tucker T. C.
Published: July 2010

Evidence is presented to show the validity of soil and petiole analyses as diagnostic tools in planning N fertilizer programs. A highly significant correlation was found between the initial soil nitrate level and yield of seed cotton (Gossy pium hirsutum) without additional N when the soil was sampled as outlined. The level of nitrate N in leaf petioles was found to be a good indicator of the N nutrition of the cotton plant. The N needs of cotton can be determined throughout the growing season by utilizing soil and petiole analyses.
Partially Acidulated Rock Phosphate as a Source of Phosphorus to Plants: III. Uptake by Corn from Soils of Different Calcium Status
Authors: McLean E. O. , Balam B. S.
Published: July 2010

Rock phosphate was treated with H3PO4 to give 5, 10, 50, and 100% acidulations relative to triple superphosphate. The resulting materials were applied to three Ohio soils brought to different calcium levels. The P uptake and the percentage recovery of added P by corn plants (Zea mays L.) were determined. The soils 1/3‐3/4 Ca saturated generally resulted in better yields, P uptake, and P fertilizer recovery than other Ca saturations. Acidulations beyond 10% in soils less than 1/3 Ca saturated and beyond 50% in soils 1/3‐3/4 Ca saturated were generally not significantly beneficial to P uptake or percentage recovery of added P. Comparison of fertilizers with similar amounts of soluble phosphate but different amounts of insoluble (unreacted) rock phosphate indicated that on the average 1.3 to 1.5 times as much of the added “available” phosphorus was recovered where more insoluble P was present. This was attributed to the reaction of the soil‐formed H3PO4 with unreacted rock phosphate so that less phosphate was fixed by solubilized Al and Fe compounds.
An Instrument for in Situ Measurements of Soil Moisture Flow and Suction
Authors: Cary J. W.
Published: July 2010

A soil moisture flux transducer was built and tested in the laboratory under steady‐state conditions in a column of Portneuf silt loam soil. Initial data indicate that the instrument may be developed into a useful field research tool. Its principal advantage is that measurements of moisture flow may be made without any prior information concerning the unsaturated hydraulic conductivity of the soil. Rather, one needs to know only a soil moisture convergence factor which is dependent on the state of the soil and the design of the transducer. While this convergence factor is dependent upon the soil moisture content, the dependence appears to be nearly an order of magnitude less than the dependence of hydraulic conductivity on soil moisture content. It may prove possible to develop the unit for installation in the field to provide continuous measurements of the unsaturated soil moisture flow in the tensiometer range with errors no greater than those arising from the natural heterogeneity of the soil.
A Comparison between Two Methods of Determining the Thermal Diffusivity of a Moist Soil
Authors: Hadas A.
Published: July 2010

Two types of solutions of the heat flow equation were discussed and proposed recently as methods for evaluating the thermal diffusivity of soils. The first one is the harmonic solution for a sine heat wave while the second uses the Laplace transform for solving the heat flow equation. This work was carried out in order to compare the thermal diffusivity values obtained by using these two solutions. Experimental data were analyzed for dry soil as well as for wet soil having 4.5, 7.8, and 14.5% water on dry weight basis.

The thermal treatments were: three types of heat waves, a sine wave, half square and a full square wave, all having an amplitude of 6C and periods of 8 and 16 min.

For dry soil the sine wave solution yielded lower values than the Laplace solution did. For the wet soil the same trend was observed for the short period while for the longer period a cross‐over, namely, higher values were obtained using the sine wave solution than those obtained by the Laplace solution.

These differences are discussed in the light of the experimental conditions and moisture transfer during the heating period.
Mineralization of Organic Phosphorus in Soils as Affected by Addition of Inorganic Phosphorus
Authors: Wier D. R. , Black C. A.
Published: July 2010

The enhancement of mineralization of soil organic P that previous investigators had reported as resulting from incubation of soils with added inorganic P was not found in laboratory experiments. Previously reported recoveries of more than 100% of inorganic P added to certain alkaline soils before incubation, which also might be a consequence of enhanced mineralization of soil organic P, could not be reproduced except where the P was added in an acidified solution. Presumably an acidified solution was used by mistake in the previous work.
Dissolution and Availability to Plants of Rock Phosphates of Igneous and Sedimentary Origins
Authors: Höweler R. H. , Woodruff C. M.
Published: July 2010

Three studies were conducted to test the P supplying power of Missouri apatite of igneous origin relative to that of Florida and Arkansas rock phosphates of sedimentary origins. The analyses of the materials showed that Missouri apatite contained as much as 15.4% P, while Florida and Arkansas rock phosphates contained 14.5% and 9.6% P. Arkansas phosphate contained almost 20% CaCO3, Flordia had 9% CaCO3, most of which was incorporated in the apatite structure, and Missouri apatite had only 5.6% CaCO3 as an impurity.

The absence of carbonate from the Missouri apatite crystal resulted in a very strong crystalline structure. Incremental dissolution by dilute HCl as well as a greenhouse study with corn and soybeans revealed that this igneous apatite released its P very slowly. The rock phosphates of sedimentary origin with their small degree of crystallinity were decomposed more easily. Florida rock phosphate was most effective in supplying the plant with P while the low P as well as the high lime contents of Arkansas rock reduced the effectiveness of this material as a P fertilizer.
Inorganic Phosphorus Fractions and Their Relationship to Residual Value of Large Applications of Phosphorus on High Phosphorus Fixing Soils
Authors: Shelton J. E. , Coleman N. T.
Published: July 2010

Large applications of P to a high P fixing soil were rapidly converted into Al and Fe‐P. Over an 8 year period a decrease in Al‐P with an increase in Fe‐P occurred. Reductant soluble Fe‐P occurred 3 and 5 years following P applications at 1,371 kg/ha (1224 lb/acre) and 685 kg/ha (612 lb/acre).

Soil test P was highly correlated with Al‐P. Regression analysis indicates that increasing rates of P application, or increasing Al‐P level, up to the reported P adsorption maximum, resulted in greater efficiency in increasing the soil test P. At a 1.371 kg/ha rate of application, which was above the reported 719 kg/ha (642 lb/acre) adsorption maximum, the efficiency was greater than at 343 kg/ha (306 lb/acre) rate of application but slightly less than at 685 kg/ha application rate.

A method of investigating long‐term field equilibrium conditions in a relatively short period, by boiling, was investigated and resulted in equilibrium conditions requiring several years under field conditions. It is suggested that this method when coupled with other data may be used as a means of estimating P applications which would result in sufficient available P for maximum yields over an extended period.
Rubidium‐Sodium Exchange on Kaolinite and Bentonite
Authors: Kunishi H. M. , Heald W. R.
Published: July 2010

Experimental data on the exchange between Rb and Na on kaolinite and bentonite clays were examined in terms of the exchange equation of Heald et al. The results could be interpreted in terms of a single selectivity factor, describing the relative tendencies of the two ions to form ion pairs with the charge on the clay surface when it was assumed that the amount of each ion present in the form of ion pairs was a constant fraction of the total amount of that ion present.
Soil Properties Influencing Differential Ca to Sr Adsorption
Authors: Khasawneh F. E. , Juo A. S. R. , Barber S. A.
Published: July 2010

The selectivity coefficient, the ratio of Sr to Ca as exchangeable cations divided by the ratio of Sr to Ca in solution, was found to vary from 0.61 to 1.51 on 63 Indiana soils. Soil factors influencing the variation in kc values were studied on selected soils where kc was determined after equilibration of the soil with an 0.1N chloride solution of Ca and Sr having a Ca/Sr molar ratio of approximately 190:1.

Organic matter was negatively correlated with the kc value (r = 0.83). Removal of the organic matter with H2O2 on nine soils increased the kc value. The magnitude of the increase was correlated with the percent organic matter in the soil (r = 0.89). The organic fraction of the soil adsorbed Ca preferentially to Sr. The inorganic fraction in most instances adsorbed Sr preferentially.
Yield and Nutrient Removal by Corn (Zea mays L.) for Grain as Influenced by Fertilizer, Plant Population, and Hybrid
Authors: Robertson W. K. , Thompson L. G. , Hammond L. C.
Published: July 2010

The fertilizer requirements of corn (Zea mays L.) on a fine sand with a constant water table depended on the season. In 1 year of 3, yields increased to the highest rate of N‐P‐K (664‐196‐556 kg/ha), however, on the average, requirements were half these quantities. For well‐fertilized corn, the ear yield constituted one‐half the weight of the above ground plant.

At the highest yield the N, P, and K concentrations in the ear were 1.5, 0.22, and 0.32%, respectively. The uptake in the fodder of N, P, and K averaged 0.0227, 0.0050, and 0.0185 kg, respectively, per kg of ear corn produced (approximately 1.58, 0.35, and 1.30 lb in the fodder per bushel of grain produced). Of this, 67, 51, and 20%, respectively, were in the ear.

Ear corn yields were not consistently affected by plant density (47,840, 68,890, and 95,680 plants/ha). Number of ears increased with stand, but ear weight and quality decreased.

Considerable seasonal variations were noted between hybrids. Windy conditions, during and immediately after tasselling, lodged tall varieties more than short varieties.

Although the amounts of P and K applied in the fertilizers were well in excess of those removed in the crop, relatively small amounts of these nutrients could be extracted from the soil by 1N NH4OAc (pH 4.8).
A Sandculture Study of Chloride Toxicity to Mature Avocado Trees
Authors: Bingham F. T. , Fenn L. B. , Oertli J. J.
Published: July 2010

Mature avocado trees (Persea americana) were grown outdoors in large sandcultures under treatments ranging from 0 to 20 meq Cl/liter. All solutions were adequately supplied with essential elements and the solutions were isoosmotic. Chloride injury symptoms include reduced tree growth, transpiration, leaf burn, premature leaf abscession, and possibly reduced fruit production. Criteria for evaluating soil, irrigation water, and leaf analysis are presented.

A mechanism for Cl injury is proposed to be the result of excessive accumulation of chlorides in xylem fluids in the leaf, which promotes dehydration and permanent injury to the cells. Rather than being a specific effect, the effect appears to be a special case of osmotic injury.
Sand and Cotton Bur Mulches, Bermudagrass Sod, and Bare Soil Effects on: II. Salt Leaching
Authors: Heilman M. D. , Wiegand C. L. , Gonzalez C. L.
Published: July 2010

Four surface cover conditions—sand mulch, cotton bur mulch (Gossypium hirsutum), coastal bermudagrass sod (Cynodon dactylon L.), and bare fallow—were evaluated with and without gypsum for salinity reclamation under natural rainfall conditions in the Lower Rio Grande Valley of Texas. The electrical conductivity of saturated soil extracts (ECe) decreased in the surface 61 cm of all treatments. The sand mulch was the most effective; ECe decreased from 17.6 mmhos/cm initially to 2.8 mmhos/cm the first year of treatment. The ECe changed only from 22.1 mmhos/cm to 15.8 mmhos/cm in 3 years under bermudagrass sod. Salt accumulated below the 61‐cm depth in the bermudagrass plots because of moisture extraction from the saline water table. No benefit was derived from the addition of gypsum. Following termination of the study, ECe remained unchanged after one cropping season of sorghum (Sorghum vulgare). Yields of both grain and forage were a function of reclamation wrought by the treatments. There was a net reduction of salt from the 0‐ to 213‐cm profile for sand and bur treatments, whereas a net increase occurred for the bare fallow and bermudagrass treatments.
Cation‐Exchange Equilibrium Constants of Aluminum‐Saturated Montmorillonite and Vermiculite Clays
Authors: Foscolos A. E.
Published: July 2010

Equilibrium constants of aluminum‐saturated montmorillonite and vermiculite clay minerals were studied in chloride‐salt solutions at concentrations similar to those occurring in soil. Studies were limited to cations occurring most abundantly in soil solutions, viz., H+, Na+, K+, Mg2+, and Ca2+. The order of relative replacing power in the lyotropic series was found to be: Colony Wyoming montmorillonite (90 meq/100g CEC) H < Na < Mg < Ca < K < Al; Otay California montmorillonite (125 meq/100g CEC) H < Na < Mg < Ca < Al < K; Jeffersite vermiculite (175 meq/100g CEC) Mg < Ca < H < Al < Na.
Pore Gas Composition Under Sewage Spreading
Authors: Thomas R. E. , Schwartz W. A. , Bendixen T. W.
Published: July 2010

Septic tank effluent was applied to sand in laboratory lysimeters. Dosing frequencies of 2/day and 6/day were used to observe relationships between changes in the composition of the pore gas and the clogging of the sand. The rate of clogging in the 2/day unit was less than that in the 6/day unit. This reduced rate of clogging was related to pore‐gas and moisture content changes which occurred in the sewage dosing and drainage cycles. The longer cycle of the 2/day frequency provided more oxygen over a greater percentage of the total elapsed time. In the 6/day lysimeter the rapid soil clogging, which is characteristic for anaerobic conditions, started while the oxygen concentration in the pore gas was greater than 13 percent. Water‐filled pores or water films, occurring as the result of an increase in the moisture content, may have provided anaerobic sites in the presence of the high pore‐gas oxygen. Carbon dioxide inhibition of microbial growth did not cause the rapid phase of clogging. Moisture or oxygen determinations may be suitable guides for prevention of the rapid phase of soil clogging.
Soil Erosion in Relation to Properties of Eastern and Western Washington Forest Soils
Authors: Balci A. N.
Published: July 2010

Soil was sampled under Douglas‐fir stands (Pseudotsuga meanziesii) located on similar parent materials in eastern and western Washington. Simulated rainfall applied to soil blocks showed real differences in erodibility of east‐ and west‐side soils. All soil properties tested, except texture, differed significantly between the two locations.

Over 70% of the variation in soil erodibility was accounted for by a multiple regression equation using erodibility as the dependent variable and loss on ignition, permanent wilting percent, and percent silt as independent variables. Differences in soil properties were attributed to influences of climate on production of plant litter and ensuing decomposition and incorporation of litter in soil by organisms.
Determination of Equivalent Radii for Half‐Tube and Whole‐Tube Drains in Contact With an Impermeable Barrier
Authors: Warrick A. W. , Kirkham Don
Published: July 2010

For soil‐drainage problems, we prove that a half‐tube of radius a, the diameter of which is coincident with a plane barrier, is equivalent to a whole‐tube drain of a smaller radius, b = 2a/π = 0.6366a, installed with its circumference touching the same plane barrier. The value 0.6366a lies between the limits 0.5a and 1.0a found by Kirkham in 1947. The result is applicable by analogy to all types of potential problems, such as those of electricity and heat conduction. The result is useful for applying theoretical results, found for half tubes, to whole tubes as used in practice.
Reduced Sodium Exchange Capacity in Unsaturated Flow
Authors: Mokady R. S. , Bresler E.
Published: July 2010

Flowing water with a reduced degree of saturation seems to reduce the apparent or effective cation‐exchange capacity. The experiment was performed by running water through a layered soil, thus obtaining unsaturated flow conditions. It is suggested that the flow direction induces anisotropy with respect to molecular diffusion. The hydrodynamic dispersion in the flow direction is almost unaffected. At the same time there must be some locations off the main water stream with which there is negligible mixing or molecular exchange by diffusion. One may associate to these isolated locations a prevailing direction normal to the mainstream. In this case, it can be said that the unsaturated flow induces anisotropy on ion transfer by mixing or molecular diffusion.
Native Fixed Ammonium in Hawaiian Soils
Authors: Mikami David T. , Kanehiro Yoshinori
Published: July 2010

Native fixed ammonium was found to range from 0 to 585 ppm. Volcanic ash soil horizons generally had a lower fixed ammonium content (4 to 178 ppm) than those from basalt (0 to 585 ppm). There was a general decrease of fixed ammonium concentration with depth in most of the profiles, this pattern of decrease being more pronounced in basaltic soils than in ash soils. Native fixed NH4‐nitrogen as a fraction of total nitrogen in individual horizons varied from 0 to 32.9%. This fraction was generally much greater in the basalt soils than in the ash soils. The soils did not show any definite pattern in the profile as to the relative amount of nitrogen present as native fixed ammonium. There was a highly significant relationship between native fixed ammonium and total K2O and percent mica in both ash and basalt soils. This relationship, however, does not apply to young, partially weathered soils containing primary potassium‐bearing minerals. The difference between organic C/organic N and organic C/total N ratios was generally greater in basaltic soils than in ash soils.
Two North Carolina Coastal Plain Catenas: I. Morphology and Fragipan Development
Authors: Nettleton W. D. , Daniels R. B. , McCracken R. J.
Published: July 2010

Two soil catenas of the Coastal Plain of North Carolina were studied. The older catena formed in feldspathic sediments and the wetter members have fragipans and bisequal profiles. The younger catena formed in quartz‐rich sediments and fragipans are absent in most soils. The younger catena has finer textured B horizons and thinner sola than comparable members of the older catena. The moderately well‐drained members of the two catenas are similar.
Soil and Plant Moisture Relations of Red Pine Growing on a Shallow Soil
Authors: Fisher R. F. , Stone E. L.
Published: July 2010

The relationship of plant moisture status to soil moisture content was studied in a 25‐year‐old red pine, Pinus resinosa Ait., plantation on 60 cm of channery silt loam soil over fractured siltstone bedrock. Two of the four‐tree plots received summer rainfall; rainfall was excluded from the remaining two plots by a plastic ground covering. The relative turgidity and needle moisture content of current‐ and second‐year needles were measured; only the second‐year needle relative turgidity was significantly correlated with soil moisture content. Wood moisture content was not correlated with soil moisture content. The dry weight of current‐year needles was closely related to the soil moisture availability during the period of growth. The degree to which the underlying bedrock was fractured, allowing roots to penetrate, was a primary factor in survival.
An Insoluble Manganese Ammonium Pyrophosphate Found in Polyphosphate Fertilizer Residues
Authors: Hossner L. R. , Blanchar R. W.
Published: July 2010

Seventeen ammonium polyphosphates containing 5.0–5.8% Mn were reacted with a Selma silt loam soil. Fertilizer residues formed in this manner contained from 5 to 80% of the applied Mn. A highly significant correlation (r2 = 0.92) existed between the pH of the polyphosphate fertilizer and the percent of Mn which remained in the residue. Increasing pH resulted in increasing amounts of Mn at the site of placement. There was no consistent relationship between the nonorthophosphate content of the fertilizer and Mn in the residue.

The Mn compound which preciptated in the residue was determined to be Mn3 (NH4)2 (P2O7)2 · 2H2O. It was the only Mn compound detected and was present in the 13 of the 17 polyphosphate fertilizers which had a pH greater than 2.5.
A Technique for Obtaining Undisturbed Soil Samples by Freezing in Situ
Authors: Blevins R. L. , Aubertin G. M. , Holowaychuk N.
Published: July 2010

A freezing technique employing liquid nitrogen has been developed to freeze soil blocks in situ. This technique makes it possible to collect undisturbed samples from soils that are incoherent, have an abundance of roots or have a high percentage of coarse skeletal materials. The frozen blocks can be transported to the laboratory in a frozen state and eut into desired‐size blocks for bulk density, moisture retention and micromorphological studies.
Automated Determination of Magnesium in Soil Extracts by Atomic Absorption Spectrophotometry
Authors: Griffin G. F.
Published: July 2010

A procedure for automated determination of Mg in soil extracts by atomic absorption spectrophotometry is presented. A modified Morgan solution (0.625N NH4OH + 1.25N CH3COOH, pH 4.8) was used to extract Mg from the soil. Measurement of Mg in 60 soil extracts by the proposed automated method gave results which were not different from those of an accepted manual procedure. Interferences with Mg absorbance caused by levels of Al, Si, and P higher than those found in most NH4OAc soil extracts were not great enough to necessitate use of a Sr diluent to eliminate the interferences.
Effect of Low Concentrations of Aluminum on Growth and Water and Nutrient Uptake by Cotton Roots
Authors: Lance J. C. , Pearson R. W.
Published: July 2010

Using a split root technique, the roots of 8‐day‐old cotton seedlings (Gossypium hirsutum ‘Empire’) were exposed to concentrations of 0, 0.15, 0.225, and 0.30 ppm Al for periods varying from ⅓ to 12 hours. Reductions in root weight and Ca uptake were the only effects observed after roots were exposed to 0.30 ppm Al for 1 hour. After longer exposures the uptake of water, Ca, Mg, K, P, and NO3 from ¼ Hoagland's solution was reduced. The curve of relative uptake vs. Al concentration was about the same in each case. The inhibition of Ca uptake was avoided by increasing the Ca concentration to 15 mM. Increasing the osmotic pressure did not accentuate the effect of Al on water uptake. The inhibition of all types of uptake indicates that the permeability of the plasmalemma is reduced. This might be due to interference in a function of Ca.
Independent Measurement of Matric and Osmotic Potential of Soil Water
Authors: Oster J. D. , Rawlins S. L. , Ingvalson R. D.
Published: July 2010

A technique is described that uses the operating principles of the thermocouple psychrometer and the porous plate apparatus to measure the matric and osmotic potentials of soil water without extraction of a significant amount of soil solution. The technique was tested on a Na‐saturated Gila soil to which NaCl solutions with osmotic potentials of −1, ‐2, and −6 bars were added. The standard error of measurement of the soil water potential components was ±0.04 bar. The measured osmotic potentials of the soil were lower than those of the added solutions, which can be explained by salt exclusion although mineral dissolution could contribute to these results. The technique also permitted measurement of the partial molar volume of soil water with an accuracy of about ±1%. Within this precision, the partial molar volume of soil water in this study was shown to be the same as that of pure water.
Relation of Water Application to Evaporation and Storage of Soil Water
Authors: Gardner H. R. , Gardner W. R.
Published: July 2010

Evaporation was measured from columns of Rago loam and McGrew loamy sand, to which water had been added at several rates ranging from 0.25 cm/day to 10.2 cm every 20 days. The water lost by evaporation varied from 100% of the total applied for the smallest and most frequent addition to 31.2% for the 10.2 cm of water added to McGrew soil every 20 days.

The losses from repeated cycles of the individual treatments tended to approach a constant value that was less than the potential loss. As the amount added was increased for a given evaporation period, the loss tended to approach a constant value that also was much less than the potential loss.

The cumulative evaporation curves were scaled to dimensionless variables and compared with a theoretical solution of the diffusivity equation for finite media. Using this scaling‐comparison technique, the losses from soil with two different potential evaporations were compared with predicted curves.