bluuebunny/crossref_metadata_2025 huggingface dataset:
Approximation of the Field Maximum Soil Moisture Content
Authors: Carlson Charles A.
Published: July 2010

Field maximum moisture content is defined as the recurring maximum moisture content of a soil layer in its natural position. An approximation of the field maximum is needed when daily moisture records are not available for selecting the recurring peak values. This paper presents the approximation of the field maximum moisture content from equations relating various soil and site properties.

Of the several factors investigated, the 0.06‐atm. soil moisture tension value was the only single factor that correlated significantly with the field maximum; it accounted for about 68% of the variation in the field maximum values. With a simultaneous analysis, the sand content and the wetness index of the soil layer also were found to be primary factors in estimating the field maximum moisture content. Wetness index is an arbitrary classification that rates the potential maximum wetting of the 0‐ to 12‐inch layer of soil and is dependent on the depth to a water table and the depth of wetting. Organic content and clay content were found to be secondary factors in the 0‐ to 6‐ and 6‐ to 12‐inch layers, respectively. Equations using all factors accounted for about 80% of the variation in the field maximum values. The usefulness of the equations was evaluated by application to 533 sites located throughout the United States.
Freezing‐Point Depressions in Stabilized Soil Aggregates, Synthetic Soil, and Quartz Sand
Authors: Cannell Glen H. , Gardner Walter H.
Published: July 2010

The freezing‐point method, using a small probe‐type thermistor as the sensing element, was used to study certain factors believed to lower the freezing‐point depression of soil moisture. The factors investigated were aggregate size, particle size, and undercooling temperature. The materials used were homogeneous and consisted of Palouse silt loam obtained from the A1 horizon, synthetic soil, and quartz sand.

The Palouse silt loam was treated with soil conditioner, formed into aggregates, and separated into groups of various sizes. The freezing‐point depression measured on the various groups of aggregates increased with decreasing size of aggregates. This same trend was obtained for different‐sized sand separates. With successive freezing and thawing, the freezing‐point depression decreased for Palouse silt loam aggregates but was relatively unchanged for sand separates.

The synthetic soil was made from ground quartz sand and illite clay. Part of the synthetic soil was treated with various rates of soil conditioner and formed into aggregates. The freezing‐point depression, made on aggregates of 1 to 2 mm. diameter, increased with increasing rate of soil conditioner.

Different undercooling temperatures had little effect in changing the freezing‐point depression for Palouse silt loam or sands. However, the freezing‐point depression was increased with increasing undercooling temperatures for nonaggregated synthetic acid‐soil.
Aluminum Fixation in a Synthetic Cation Exchanger
Authors: Hsu Pa Ho , Rich C. I.
Published: July 2010

Previous studies of soils have indicated fixation of Al as a poistively charged ion or polymer by some clay minerals. To avoid reactions with structural Al in clays, a synthetic cation‐exchange resin, Dowex‐50, was employed in a preliminary study of Al fixation. This resin was Al‐saturated and then serially titrated with NaOH. In a similar experiment, AlCl3 was added in an amount equivalent to the Al in the resin, prior to titration. In a third experiment the same amount of Al‐saturated resin was added to different volumes of solutions containing NaOH and AlCl3 in molar ratios of 0.296, 1.185, and 2.37, respectively. All of these experiments indicate that the only exchangeable Al ion was Al3+ and that in the acid range nonexchangeable Al was fixed so that on the average one positive charge of the resin was countered by one Al ion. A gibbsite‐like ring structure having 6 Al ions, 12 OH ions and 12 water molecules is proposed as the principal fixed hydroxy‐Al polymer. The polymer may be formed in place from smaller chain‐like polymers and fixed because of its large size and high charge.
The Effectiveness of Various Manganese Materials in Supplying Manganese to Crops
Authors: Shepherd L. , Lawton K. , Davis J. F.
Published: July 2010

Field tests on Houghton muck and greenhouse studies on alkaline organic and mineral soils were conducted to determine the comparative effectiveness of several manganese carriers as measured by yield response and manganese content of crops. Spray, broadcast, and banding methods of application were studied in field tests and mixing vs. banding of carriers was studied in the greenhouse. Carriers used in the field studies were manganese sulfate, NuM, Mangasoil, NuManese, and FN 239 B frit. In addition to the above five carriers, FN 502 frit and disodium manganous EDTA were used in the greenhouse. The indicator crops were onions in the field, and corn, beans and wheat in the greenhouse.

In field studies, the methods of application in order of effectiveness in increasing the yield of onions were banding, broadcasting, and spraying. In 1957, where the manganese carriers were mixed with the basic fertilizer and banded 2 inches below the seed, a significant yield response to manganese was obtained regardless of the carrier used. No difference was observed between carriers or rates applied (10 and 20 pounds of manganese per acre).

Greenhouse results indicated a high residual value on Houghton muck for Mn EDTA followed by FN 239 B, NuManese and manganese sulfate. The difference between the latter two was nonsignificant. On the mineral soil, mixing the carriers throughout the soil gave a significant yield response only with the wheat crop when compared to band applications.
Weathering and Aluminum Interlayers in a Soil Catena: Hollis — Charlton — Sutton — Leicester
Authors: Sawhney B. L.
Published: July 2010

Large amounts of a mineral with a stable 14Å. spacing are present in clay fractions of the Hollis‐Charlton‐Sutton‐Leicester catena. When subjected to the usual procedures for the characterization of clay minerals, this mineral exhibited a behavior between that of vermiculite and chlorite. It was identified as vermiculite after interlayer aluminum was removed. Mild acid conditions and abundant illite and vermiculite in the parent micaceous schist are significant factors in forming these aluminum interlayers. The stability of aluminum interlayers both to sodium citrate and heat treatments increased with proximity to the surface. In Charlton fine sandy loam, 6 to 9 hours extraction with N sodium citrate were required to remove interlayers in the A1 horizon, whereas only 3 and 6 hours sufficed for the C and B22, respectively. The aluminum interlayers in well‐developed and well‐drained Charlton and Sutton soils are more stable to heat treatments than the material in poorly drained Leicester and shallow Hollis soils.

The cation‐exchange capacity increased as much as 30 to 40% after the removal of aluminum interlayers; the increase was greater in more stable samples. Aluminum interlayers produced experimentally in vermiculite and montmorillonite resulted in stable 14Å. spacing and lowered the cation‐exchange capacity of the original minerals considerably.
Effects of Electrolyte Imbibition Upon Cation‐Exchange Behavior of Soils
Authors: Thomas Grant W.
Published: July 2010

Ion‐exchange chromatography was employed to study the effects of electrolyte imbibition by soils on their cation‐exchange behavior. This was accomplished by study of the shape of effluent breakthrough curves from columns of Ca‐saturated soils to which either Al+3 or K+ solutions were added. B‐horizon samples of Cecil, Lloyd and Davidson, and the Ap horizon of a Yolo soil were employed in the study.

Comparison of experimental effluent curves with those predicted by the modified Walter equation showed a large discrepancy when anion interaction with soils was encountered. Anion distribution coefficients (Kd's) varied in the order Cl‐ = NO3‐ < SO4‐2 < H2PO4‐ on a Ca‐Lloyd soil. Only H2PO4‐ had a Kd above zero on the Yolo soil. Column “symmetry values” for Ca+2 → K+ exchange were reduced as electrolyte imbibition by soils increased. Practical implications of these results are discussed.
Yield Response in Experiments With Phosphorus Fertilizers in Relation to: I. Meaningful Differences Among Sources on Acid Soils of the Southeastern States
Authors: Terman G. L.
Published: July 2010

Yield results from 174 phosphorus rate and source experiments conducted in the Southeast, each including a response curve with CSP (concentrated superphosphate), were examined in relation to the nature of the response and experimental error.

In only a few of the tests with various crops showing yield response to P was it possible at the 5% probability level to measure differences among citrate‐ and watersoluble sources which were from one‐half to twice as effective as CSP. Under the conditions where grown, cotton was the poorest crop for this purpose, corn and small grain grown for grain were intermediate, and annual forage was best. The possibility of measuring differences among sources decreased with increase in soil P level and with increase in the rate of application of P at which the comparison was made.

Estimated limiting yields of cotton on low‐yielding sites without applied P were lower than most of the check yields at sites of higher productivity. A similar, but less pronounced situation prevailed with corn, but not with small grain. Deficiency of water is thought to be the chief factor limiting yields of summer‐grown cotton and corn at all yield levels, but not of winter‐grown small grain.
The Effect of Associated Salts on Transformations of Monocalcium Phosphate Monohydrate at the Site of Application
Authors: Bouldin D. R. , Lehr J. R. , Sample E. C.
Published: July 2010

The effect of associated nonphosphatic salts on the transformation of reagent‐grade monocalcium phosphate monohydrate (MCP) during dissolution at the granule site was examined in Hartsells fine sandy loam (pH 5.2) and in calcareous Webster silty clay loam (pH 8.3).

The fraction of the added phosphorous that remained as a residue at the granule site varied from 92% when MCP was mixed with CaCO3, to only 2% when ammonium sulfate was mixed with MCP. Uptake of phosphorus by plants grown on the soil‐fertilizer systems after removal of the residues indicated that plant response was influenced by both the quantity of phosphorus actually transported into the soil, and the composition of the solution in which the phosphorus was transported.

The data further support the concept that during dissolution of the granule, the soil has relatively little influence on the chemistry of the reactions taking place in the granule. Consequently, laboratory phase‐rule studies may be quite useful in estimating: (a) the fraction of phosphorus that will remain as a residue at the placement site, and (b) the composition of the solution leaving the granule. The latter is of utmost importance in studies of soil‐fertilizer phosphorus reactions.
The Availability of Chelated Mn to Millet and Its Equilibria With Other Forms of Mn in the Soil
Authors: Walker John M. , Barber Stanley A.
Published: July 2010

The use of insoluble soil‐chelated Mn, in addition to exchangeable Mn, did not increase the predictability of available Mn. In this study, 12 Indiana soils varying in organic matter, pH, texture, and parent material were collected and treated to give two levels of Mn and acidity. Available Mn was determined by cropping the soils with German Millet.

Exchangeable Mn was the most important factor in determining available Mn. Since chelated and exchangeable Mn were highly correlated, the true effect of chelated Mn may not have been apparent. Inclusion of the interaction chelated Mn times percent organic matter highly significantly increased the ability to predict available Mn. Soil pH was also significant in predicting available Mn.

The increase in chelated and exchangeable Mn on airdrying of the soils was related to total soil Mn.
The Efficiency of Various Particle‐Size Fractions of Limestone
Authors: Motto H. L. , Melsted S. W.
Published: July 2010

The relative efficiency of various fractions of a calcitic limestone was studied under greenhouse conditions. Pure calcium carbonate, a commercial sample of agricultural limestone, and 6 particle‐size fractions separated from this commercial sample were applied at different rates to 3 acid soils. The soils were sampled at various times and the pH determined. The changes in pH with time followed an expression of the form, pHf = pHo + b Log (1 + t). The factor b varied with rate of application, particle size, and soil.

The limestone particles in the 10‐ to 28‐mesh size fraction were, in general, 14% as effective as those in the < 100‐mesh fraction, and particles > 10 mesh were essentially of no value. The efficiency of the commercial sample of agricultural limestone was approximately equal to that exhibited by the 40‐ to 60‐mesh fraction of the sample. The results indicate that, for practical purposes, a large portion of commercial limestone should be ground fine enough to pass a 40‐mesh sieve.
Fertilizer Evaluation: IV. Use of P32‐Labeled Fertilizers
Authors: Bouldin D. R. , Black C. A.
Published: July 2010

Two different measures of the yield of fertilizer phosphorus were defined as follows: (1) The net increase in yield of phosphorus from fertilization is equal to the yield of phosphorus in the phosphate‐fertilized crop minus the yield of phosphorus in the control. (2) The yield of true fertilizer phosphorus is the yield of the atoms of phosphorus actually applied in the fertilizer and is equal to the product of (a) the yield of phosphorus in the phosphate‐fertilized crop and (b) the ratio of the specific activity of phosphorus in the crop to that in the fertilizer. Measurements of these two kinds of yields of fertilizer phosphorus were made on a crop grown in greenhouse cultures on 6 soils with 4 particle sizes of P32‐tagged monobasic sodium phosphate applied at 4 rates. The net increases in yield of phosphorus from fertilization exceeded the yields of true fertilizer phosphorus, and the difference between these two values increased with the quantity of labile phosphorus in the soil. These observations can be explained on the basis of (a) enhanced growth of roots and absorption of soil phosphorus in the nonfertilizer‐affected soil in the presence of fertilizer, (b) enhanced absorption of soil phosphorus in the fertilizer‐affected soil, or (c) a combination of (a) and (b), but no evidence permitting a choice of hypotheses was obtained.
Influence of Molybdenum on Growth and Composition of Alfalfa and Distribution of Molybdenum in a Cecil‐Lloyd Soil
Authors: Giddens Joel , Perkins H. F.
Published: July 2010

Sodium molybdate was applied annually at a rate of 8 ounces per acre to alfalfa receiving 500 and 4000 pounds limestone. Beginning in the fall of the second year of growth, the low lime treatment plus molybdenum yield was about the same as the high lime treatment. After 3 years, alfalfa on the high lime treatment responded to molybdenum. Liming increased the molybdenum content of alfalfa in 1956 but did not consistently do so in 1959. The molybdenum content of alfalfa was not excessive after six applications. Molybdenum did not move downward in the Cecil‐Lloyd soil profile.
Stubble Mulching With Various Types of Machinery
Authors: Fenster C. R.
Published: July 2010

Stubble‐mulch farming has been recognized as the simplest and surest way of preventing wind erosion in the Great Plains. Maintaining residues for adequate soil protection while controlling the weeds and preparing the seedbed has been a major problem in a stubble‐mulch program. Reduction of surface residues should be held to a minimum unless they are excessive. Tillage and planting tools have various characteristics in their ability to conserve or reduce residues, to work in heavy residues, to control weeds, to penetrate the soil and keep the soil in good tilth for proper germination and plant growth. Satisfactory stubble‐mulch tillage equipment is now available from major implement companies. The correct machines can be selected by making an inventory of the residues at the beginning of the tillage season, and by determining the amount of residues necessary to protect a given piece of land. With proper equipment, knowledge and ability, a year‐round system of managing plant residues can be used in which all tilling, planting, cultivating, and harvesting operations are performed to keep a constant protective cover on the land.
Growth and Water Absorption by Corn as Influenced by Soil Moisture Tension, Moisture Content, and Relative Humidity
Authors: Peters D. B.
Published: July 2010

When plants were subjectd to a high evaporative demand, i.e., low relative humidity, growth was found to be profoundly influenced by both soil moisture tension and moisture content. However, at low evaporative demand, other factors being held constant, growth was influenced by moisture tension and moisture content in only a minor way. Thus, it is shown that evaluation of growth from the standpoint of water use must consider the total free energy path causing water movement. Water use could not be evaluated precisely with the experimental technique used because of the large growth differences and the inability to measure energy absorption by plants.
Influence of Moisture on the Effectiveness of Winter‐Applied Nitrogen Fertilizers
Authors: Kurtz L. T. , Owens L. D. , Hauck R. D.
Published: July 2010

Two field experiments were conducted to compare the effectiveness of 3 forms of N when applied in the winter to a silt loam soil receiving 3 different rates of moisture. Ammonium sulfate, sodium or calcium nitrate, and urea were applied in the winter at the rates of 0, 60, 120, and 240 pounds of N per acre. The moisture rates ranging from 9 to 29 inches were established for the 5 months between fertilizer application and crop seeding. Four forage crops were then grown successively on the plots over a period of 2 years. Yield and nitrogen contents of the crops were determined for each plot.

Nitrogen contents of crops from fertilized and unfertilized plots were, in general, inversely proportional to the amount of moisture applied to the plots during the winter and spring. Crop uptake of N from plots receiving ammonium, urea, and nitrate N was generally similar at lower moisture and N rates. However, uptake was less from nitrate‐treated plots than from the corresponding ammonium‐treated plots when applications of either N or moisture were increased to high levels. Experimental conditions were probably conductive to nitrogen losses through leaching and denitrification.
Vertical Distribution of Soil Phosphorus and Potassium on Several Established Alfalfa Stands That Received Various Rates of Annual Fertilization
Authors: Wells K. L. , Parks W. L.
Published: July 2010

Available soil phosphorus, available soil potassium, calcium, magnesium, and pH were determined at various depths on four soil profiles under established stands of alfalfa. Three experiments were set up in a complete factorial design using four rates of annual phosphate application and five rates of annual potash application. The fourth experiment received five annual applications of potassium and no applications of phosphate since it was on soil inherently high in phosphate.

Available potassium after 4 years of annual applications of potash on three soils and 5 years on one soil was concentrated in the 0‐ to 6‐inch layer. Only a slight movement of potassium into depths below 6 inches was noted even at high rates of annual potash fertilization. Available soil phosphorus was found to be concentrated in the 0‐ to 3‐inch layer. It was found that annual potash and phosphate applications had little effect on soil reaction.

Significant difference in yield at the 0.05 level of probability was found between the 0‐ and the 100‐pound‐peracre annual potash treatment in each experiment, and between the 0‐ and the 60‐pound‐per‐acre annual phosphate treatment on those experiments receiving phosphate fertilization. No significant response to higher rates of annual todressing was obtained.

Yield data were correlated with soil test potassium values of various soil layers. A poor correlation was found to exist between soil test potassium values and yield. Correlation values were increased by addition of phosphorus soil test values into the equation.
Cobalt Uptake by Plants from Cobalt Impregnated Soil Minerals
Authors: Kabata Alina , Beeson Kenneth C.
Published: July 2010

A water‐soluble Co salt applied to soils will result in a greatly increased uptake by crop plants for a short period. Although most of this Co is retained in the soil it gradually becomes unavailable and its effect may entirely disappear within 10 years. Since soil minerals are important factors in the Co supply to the soil solution the relative uptake of Co from substrates containing Co‐impregnated bentonite, kaolin, hematite and muscovite treated in a manner to exclude exchangeable Co was investigated.

The highest sorption of Co was found in muscovite, but the highest percentage of sorbed Co soluble in 0.1N HCl was found in the bentonite. Ladino clover and orchardgrass absorbed several‐fold more Co from bentonite than from the other minerals, and there was a correlation between this uptake of Co and the 0.1N HCl‐soluble Co in the bentonite‐sand culture at the conclusion of the experiment. In all cases the total uptake of Co was only a small fraction of the total supply of Co in the substrate.
Release of Nonexchangeable Soil Potassium During Short Periods of Cropping and Sodium Tetraphenylboron Extraction
Authors: Scott A. D. , Welch L. F.
Published: July 2010

Undried soils were cropped in the greenhouse to determine the short‐term release of nonexchangeable K under intensive cropping conditions. Using corn root mats with plants intact, it was found that 218, 59, 50 and −1 ppm. nonexchangeable K was released in 10 days by Marshall surface and subsoil and Clarion surface and subsoil samples, respectively, that had received no NH4 or K additions. It was concluded that this short‐term cropping method could be used to study factors that affect the availability of nonexchangeable soil K to plants.

Nonexchangeable K was also extracted from the undried soils by two chemical methods that tend to reduce the blocking effect of replaced K. Single extractions with a NaOAc‐NaBPh4 solution removed more nonexchangeable K than five successive NaCl‐HCl extractions or 5‐day cropping periods. The corn plants and the NaCl‐HCl solution, however, continued to remove K when the extraction period was increased whereas the NaOAc‐NaBPh4 solution did not.
Determination of Consumptive Use of Water by Irrigated Crops in the Western United States
Authors: Robins J. S. , Haise H. R.
Published: July 2010

Certain of the many procedures for indirect estimation of consumptive use are discussed including the Blaney‐Criddle, Thornthwaite and Penman methods as well as evaporimeters such as atmometers and evaporation pans. The applicability and limitations in use of these procedures are analyzed including type and quality of data available, microclimatic effects and use of derived information. Problems involved in determining evapotranspiration or consumptive use by irrigated crops are discussed and their implications in use of data obtained for specific situations are analyzed. These include sampling precision, frequency and time of sampling, crop rooting depth and stage of growth, type of crop, moisture status effects, climatic effects including advected heat, and percolation losses beyond the sampling zone.
Soil Tensile Strength by Centrifugation
Authors: Vomocil J. A. , Waldron L. J. , Chancellor W. J.
Published: July 2010

Tensile stress was applied to soil samples by the body force developed when they were rotated in a specially designed centrifuge head. Cylinders or briquets of soil were positioned in the head with their long axes perpendicular to the axis of rotation. The magnitude of applied tensile stress was calculated from sample dimensions, sample mass and speed of rotation. Tensile strength was defined as the applied tensile stress when the sample failed.

Tests were made on samples prepared from five soil types. Three methods of preparation were used that produced samples with water contents ranging from oven‐dry to that corresponding to approximately ⅓‐atm. suction. The method proved satisfactory over this range of water contents. Experience and calculations indicated it could be used over a range of strengths from 15 to 4000 millibars. Reproducibility varied with the method of sample preparation. The coefficient of variation ranged from 10 to 25%.
The Influence of Phosphorus Fertilization and Moisture on Growth and Nutrient Absorption by Spring Wheat: II. Soil and Fertilizer P Uptake in Plants
Authors: Power J. F. , Reichman G. A. , Grunes D. L.
Published: July 2010

The availability and uptake of soil and fertilizer P was studied with dryland spring wheat under four moisture regimes in a field experiment in eastern Montana. The Chestnut soil used was moderately low in available P (6.2 ppm. NaHCO3‐soluble P per acre).

Fertilization with P, higher soil moisture supplies at seeding time, and additional precipitation during the growing season, all increased total P uptake by spring wheat at all stages of plant growth. Interactions between any of these three factors seldom affected total P uptake at any stage of growth.

Increasing the supply of soil moisture at seeding or growing‐season precipitation increased plant uptake of soil P. However, P fertilization reduced soil P uptake. Moisture supplies at seeding and growing‐season precipitation did not affect uptake of fertilizer P, except at the tillering stage of growth. The percent of total P in plant material derived from fertilizer was generally lowest in treatments receiving the most moisture, either as stored soil moisture or growing‐season precipitation. NaHCO3‐extractable P was not influenced appreciably by moisture conditions.
Greenhouse Measurement of Available Sulfur Using Radioactive sulfur
Authors: Nearpass D. C. , Fried M. , Kilmer V. J.
Published: July 2010

Available sulfur was determined in a greenhouse experiment with 30 surface soils from the Southeastern United States by growing cotton plants at six levels of applied sulfate‐sulfur, 0, 2, 4, 8, 16, and 32 ppm. The A value technique involving radiosulfur was used as an index of available sulfur.

Sulfur A values varied from 9.8 ppm. to 42 ppm. A high degree of correlation was obtained between A values and the percent sulfur in the control plants. Growth responses from applied sulfate‐sulfur were also related to percent sulfur in the control plants and to A value sulfur in the soil. The total uptake of sulfur also was related closely to the total available sulfur in the soil (A value plus fertilizer sulfur). A sixteen‐fold increase in the rate of sulfur addition increased the A value by approximately 20%.
Derivation of State Factor Equations of Soils and Ecosystems
Authors: Jenny Hans
Published: July 2010

The ecosystem is a piece of landscape having artificial boundaries. Changes in ecosystem properties are viewed as gains minus losses or influxes minus outfluxes of matter and energy. The fluxes are expressed as products of gradients and permeation. The outside potentials of the flux gradients are identified with the environmental soil‐forming factors, particularly climate and biotic factor. Pedogenic functions as now rewritten offer psychological and typographical advantages.
Runoff and Erosion Losses from Mexico Silt Loam in Relation to Fertilization and Other Management Practices
Authors: Whitaker F. D. , Jamison V. C. , Thornton J. F.
Published: July 2010

Results from the runoff‐erosion plots on claypan soils at McCredie, Missouri, are summarized. With improvement due to fertilization and sod rotations, the performance of these soils approaches that of the better soils of Missouri. Where adequate fertility is supplied the chief advantage of growing corn in a sod‐based rotation over continuous corn is the reduction in the time the soil is without protective cover. The critical period found for erosion losses from corn was from the time of seedbed preparation until the growing crop provided an adequate canopy. Erosion losses for rotation corn were about 60% as high as for continuous corn from intense rain storms that occurred during this period. Average soil and water losses from adequately fertilized soil were less for corn in rotation than for continuous corn during the corn growing season. Seedbed preparation by subtillage so as to leave shredded cornstalks on or near the surface reduced erosion losses.
Growth and Ca Uptake by Plants as Affected by Rate and Depth of Liming
Authors: Hourigan W. R. , Franklin R. E. , McLean E. O. , Bhumbla D. R.
Published: July 2010

The study involved the liming of two acid soils, one high in extractable Al and one of similar pH, but low in extractable Al. Portions of each soil were treated in the laboratory with Ca(OH)2 (labeled with Ca45) to bring the pH to three levels. One of the soils also had been maintained in the field at the same pH levels for many years. Three depths of topsoil were used with corresponding depths of subsoil. These soils were placed in 18‐inch cylinders and cropped to alfalfa.

Results indicated that plant yields, root proliferation, and consequent uptake of Ca depend largely on adequate level of lime in both topsoil and subsoil. However, if sufficient lime was applied to the topsoil, near maximum yields were obtained regardless of the lime level of the subsoil. Subsoil liming had minor effects on yield and uptake of Ca except when the topsoil was shallow and more acid. The soil with the highest level of Al responded proportionally more to the lime added. Freshly added Ca appeared to be more available to alfalfa than Ca added earlier in the field. The percentage of Ca from the topsoil‐applied source increased from 8 to 100% as the rate of liming increased from ½ to 8 tons per acre in a 3‐inch layer of the most acid soil. With increased level of lime in the subsoil, smaller percentages came from the Ca applied to the topsoil. Root growth generally reflected what yields and Ca uptake had indicated. Root cation‐exchange capacities increased with increased rate of liming.
A Self‐Adjusting, Null‐Point Tensiometer
Authors: Leonard Ralph A. , Low Philip F.
Published: July 2010

This paper describes a new tensiometer which does not allow water passage through the porous cup and which automatically adjusts the measuring manometer to the correct tension value. It can be used to measure dynamic as well as static tensions. Performance data, which are given and discussed, indicate the accuracy of the tensiometer is within 2%.
The Use of Thermometric Titrations in Soil Chemistry Studies
Authors: Ragland John L.
Published: July 2010

It was determined that a thermometric titration procedure could be used to obtain the cation‐exchange capacities and heats of neutralization of acid‐saturated clays. The endpoints of these titration curves were much sharper than those commonly obtained by potentiometric or conductometric methods.

Cation‐exchange capacities calculated from thermometric titration curves of H‐exchanges agreed fairly well with those determined by the BaCl2‐TEA method. Heats of neutralization for Arizona, Mississippi, Southern and Utah bentonites were found to be: −13.3 ±2, −15.9 ±3, −16.1 ±1 and −15.5 ±2 kcal. per eq., respectively. The heat of neutralization of humic acid was −13.2 ±1 kcal. per eq. and that of Al‐saturated Mississippi bentonite was −5.5 kcal. per eq. The large difference in the heat of neutralization of the H‐ and Al‐saturated exchangers causes titration curves for the two to have widely differing slopes. This allows determination of the proportions of H and Al saturations of mixed H‐Al clays from the titration curves.

The possible use of thermometric titrations in determining the course, mechanism and rate of a number of chemical reactions in soils is discussed and concluded to be excellent.
Measurement of Microbial Thermogenesis in Soil
Authors: Clark Francis E. , Jackson Ray D. , Gardner Herbert R.
Published: July 2010

Microbially induced temperature changes were measured in laboratory soil lots without vacuum insulation or adiabatic control. The instrumentation consisted of thermistors, a 52‐point stepping switch, and a bridge‐type strip‐chart recorder. The thermistors were variously positioned in soil quantities of 25 g., 3.3 kg., and 39.6 kg. The temperature changes were measured on an alluvial sandy loam, unamended or amended with either alfalfa meal or sucrose, at rates ranging from 0.1 to 1.0%. Temperature elevations of the order of 1.5°C. were observed in the 39.6 kg. uninsulated soil lots containing 1.0% alfalfa meal and 5.3°C. in 3.3‐kg. soil lots similarly amended and incubated in insulated containers. Addition of 1.0% alfalfa meal to 25 g. soil in uninsulated glass containers led to a maximum rise of 0.22°C.

In other work, soil temperature values were determined in various soil lots given lesser rates of organic amendments. The data obtained show that organic residues in soil can cause local areas within which microbially induced thermogenesis is measurable for intervals of several days, or even weeks, despite the relatively high specific heat capacity and conductivity of moist soil.
Zirconium Content of Coarse Silt in Loess and Till Of Wisconsin Age in Northern Illinois
Authors: Alexander J. D. , Beavers A. H. , Johnson P. R.
Published: July 2010

The zirconium content of the course silt fraction of 11 calcareous Wisconsin age till samples and 13 calcareous Wisconsin age loess samples was determined by the X‐ray emission spectrograph. It was found that the mean zirconium content of the loess (0.055%) was approximately twice as high as in the glacial tills (0.022%). This difference in zirconium content may be used to help distinguish loess from till where separation is difficult by field methods and also should be helpful in soil development studies.
Effect of Prescribed Burning of Forest Litter on Total Soil Nitrogen
Authors: Klemmedson J. O. , Schultz A. M. , Jenny H. , Biswell H. H.
Published: July 2010

The effect of prescribed burning of ponderosa pine forest floor on soil nitrogen was investigated. Standardized soil columns were placed under the forest floor and subjected to three burning treatments: no burn, light burn, and intense burn. One‐third of the columns were removed immediately after burning, one‐third 4 months later, and the remainder 16 months later.

All burning and post‐burning treatments showed net gains of nitrogen, those of no‐burn and light‐burn being greater than that for intense burning. The gain of nitrogen in the first inch of soil for the no‐burn and light‐burn treatments was 11.1 pounds per acre per year. This gain is attributed to leaching of the decomposing forest floor remaining after treatment and indicates a decomposition rate of 3.0%. The combined effects of light and intense burning reduced the nitrogen in the forest floor by 124 pounds per acre.
Adsorption and Desorption Phenomena of Sulfate Ions in Soils
Authors: Chao Tsun Tien , Harward M. E. , Fang S. C.
Published: July 2010

Four soils, of 15 examined, exhibited much higher adsorption of sulfate than the others.

Isotopic exchange studies indicated that sulfate which is retained by soils is in kinetic equilibrium with sulfate in solution. Adsorption‐desorption studies using retentive soils also indicated that sulfate adsorption is dependent on the concentration of the equilibrium solution. The adsorption phenomena could be described by the Freundlich type equation. The data thus indicated that the sulfate‐retentive soils did not possess adsorption maxima or definite anion exchange capacities, at least up to 500 ppm. S. Although certain soils were shown to have marked capacity to retain sulfate, the sulfate could be easily desorbed. As much as 45% of the sulfate initially adsorbed could be recovered in the first water extraction.

The lack of adsorption maxima is in contrast to cation‐exchange reactions where more definite exchange capacities are observed. These data suggest that either anion exchange is not involved in the retention of sulfate or that other mechanisms in addition to anion exchange are involved with sulfate retention by these soils.
Decomposition of Phenoxyalkyl Carboxylic Acids
Authors: Burger K. , MacRae I. C. , Alexander M.
Published: July 2010

The persistence of phenoxyalkyl carboxylic acids in soil was measured by a bioassay technique using alfalfa seedlings. Acetic, alpha‐propionic and alpha‐ and gammabutyric acid derivatives were toxic when applied to soil planted to alfalfa whereas the beta‐propionic acid derivatives showed no inhibition of the test plant. All 3,4‐dichloro‐ and 2,4,5‐trichlorophenoxyalkyl carboxylic acids exhibited prolonged persistence in soil. The duration of phytotoxicity in soil receiving 4‐chloro‐, 2,4‐dichloro‐ and 2‐methyl‐4‐chlorophenoxyalkyl carboxylic acids was governed by the type and linkage of the aliphatic side chain.

A Flavobacterium sp. active in the degradation of phenoxybutyric acids was isolated. The bacterium metabolized only phenoxybutyric acids having no meta chlorine on the aromatic ring. In the decomposition, the organic chlorine was liberated and the aromatic ring cleaved.

The results demonstrate that specific structural characteristics of these herbicide molecules govern persistence of the compounds in soil.
A Comparison of the Amounts of Phosphorus Removed from Different Soils by Various Extractants
Authors: Breland H. L. , Sierra F. A.
Published: July 2010

The relative effects of 8 extractants on the removal of phosphorus from 7 major soil types of Florida were studied. HCl and NH4F and HCl and H2SO4 solutions extracted more phosphorus than the other extractants. The amount of phosphorus extracted by any of the extractants apparently depended, to a large extent, on the kind and amount of phosphorus compounds present in the soil as well as other factors. It was found that soils high in phosphorus required a longer extraction period to reach equilibrium than those low in phosphorus. Increasing the length of stroke of the shaking machine from 1½ to 3 inches did not significantly affect the amount of phosphorus removed from the soils. In general, an extraction time of 10 to 15 minutes was sufficient for the extraction of soil phosphorus.
An EDTA Method for the Direct Routine Determination of Calcium and Magnesium in Soils and Plant Tissue
Authors: Barrows Harold L. , Simpson Elmer C.
Published: July 2010

An EDTA procedure is described for the direct determination of Ca and Mg in soils and plant tissue. These elements are determined in the ammonium acetate leachate of soils and in the 1N HNO3 solution of the plant ash. Calcium is separated from Mg by precipitating calcium sulfate from ethanol and is determined in the precipitate. Magnesium is determined in the supernatant solution. Manganese may be present in concentrations likely to interfere with the Mg titration, but this interference is easily eliminated. The accuracy and precision of the method are well within the limits required for routine analyses.
The Effect of Rhizobial Polysaccharides on Aggregate Stability
Authors: Clapp C. E. , Davis R. J. , Waugaman S. H.
Published: July 2010

Sixteen rhizobial polysaccharides previously isolated and characterized and representing several cross‐inoculation groups were screened for aggregate stabilization effects on 10 subsoils of widely varying properties. Two additional polysaccharides of bacterial origin and three chemical compounds were included for comparison with the rhizobial products.

Artificial aggregates were prepared in acrylic plastic molds under standardized moisture conditions. An ethanolwater microslaking procedure for assessing stability was used to determine relative effects between aggregating agents and soils. At the low concentrations used, several rhizobial polysaccharides were more effective stabilizing agents on most soils than either the synthetic soil conditioner or the other reference compounds. Some general comparisons relating carboxyl content and viscosity of the rhizobial polysaccharides and clay content with aggregate stabilization are presented and discussed.
Mechanisms of Urea Adsorption by Soils
Authors: Chin Wei‐Tsung , Kroontje Wybe
Published: July 2010

Physically adsorbed urea may be easily desorbed by dilution. Chemisorbed urea existing primarily in the form of relatively stable soil organic matter‐urea complexes may, in part, be slowly dissociated upon dilution.

Differences between soil types with respect to urea adsorption were primarily related to organic matter contents. The effects of CEC, pH, and clay mineral content were found insignificant. Wet soils had a lower capacity for urea adsorption than dry soils. Considering the amounts of urea adsorbed, soils have in general a weak affinity for the urea molecule.
Community Meetings: A Device for Distributing Soil Survey Reports and for Training in Their Use
Authors: Bidwell O. W. , Bohannon R. A.
Published: July 2010

Community meetings for the distribution of soil survey reports were held in the Kansas counties of Saline, Geary, and Brown during the years of 1959, 1960, and 1961. Cooperation of the USDA Soil Conservation Service, the USDA Agricultural Stabilization & Conservation Service, the Kansas Agricultural Extension Service, and the Kansas Agricultural Experiment Station was essential in the planning and execution of the meetings. Other important elements which made the meetings successful and brought out an average of 480 persons to each of the three series of county meetings included: (1) the selection of local farm leaders to help publicize and conduct the meetings; (2) withholding distribution of the soil survey reports until the meetings; (3) bringing the party chief back to take part; and (4) using visual aids such as soil profile monoliths, soil texture samples, a large colored county soil map, and growing plants to illustrate soil deficiency symptoms.
Isotopic Exchange of Potassium in an Illite under Equilibrium Conditions
Authors: Sumner M. E. , Bolt G. H.
Published: July 2010

The kinetics of K exchange in an illite were studied using K42. The influence of various pretreatments was investigated, and a comparison was made between exchange with K42 under equilibrium conditions during 1 week and repeated extraction with 0.5 N NH4NO3 and 0.5 N NaNO3. Except for the samples containing 0.5 N CaCl2 the K42 exchange appeared to be very fast and no further increase could be observed during shaking from 6 hours up to 1 week.

Prolonged pretreatment with 0.5 N CaCl2 apparently caused an opening up of the clay lattice. The 0.5 N NH4‐extraction following this treatment always removed considerably more K than was exchangeable against K42 under equilibrium conditions.

On the other hand, extraction with 0.5 N NaNO3 removed even less than was exchangeable against K42, indicating that part of the exchangeable K was still in interlattice positions.
Controlled Release of Fertilizer Minerals by Incapsulating Membranes: I. Factors Influencing the Rate of Release
Authors: Oertli J. J. , Lunt O. R.
Published: July 2010

The availability of nutrients from inorganic fertilizer salts can be regulated through coating such materials. The release rate was investigated in several elution and leaching experiments. The release approached linearity for a considerable period; thereafter the rate dropped off. The release rate was largely independent of the pH of the elutant and of the soil pH. An increase in temperature from 10° to 20°C. almost doubled the initial release rate. The release could be regulated very efficiently through the coating thickness. There was an effect of ionic species, nitrate and ammonia being given off more rapidly than potassium or phosphates. The release was only slightly reduced under sterile conditions. It was concluded that diffusion is the most likely release mechanism and proposed that discrepancies such as the high Q10 value could be explained through possible changes in membrane properties. Coated fertilizers thus possess the properties required for regulation of the availability of nutrients: they may reduce leaching losses and provide a steady prolonged nutrient supply to plants.
Model of a Rising Nitrogen Profile in Nile Valley Alluvium, and Its Agronomic and Pedogenic Implications
Authors: Jenny Hans
Published: July 2010

Nitrogen‐depth functions in Nile Valley alluvium appear similar to those of Brunizems, but their genesis must be entirely different. Since fresh Nile mud is very rich in total nitrogen, it is proposed that the annual depositional layers, 1 mm. in thickness, undergo nitrogen losses as a result of microbial decomposition, and that for each layer the losses continue in the buried state, though at reduced rates. This model predicts quantitatively the N‐depth function actually observed. In comparison to residual soils, the Nile Valley profiles—in fact many young alluvial and loessial profiles—are inverted, the youngest horizon being on top, the oldest at the base.
Soil Hardpan Formation as Affected by Rate of Moisture Loss, Cyclic Wetting and Drying and Surface‐Applied Forces
Authors: Gerard C. J. , Cowley W. R. , Burleson C. A. , Bloodworth M. E.
Published: July 2010

A hypothesis was proposed by Gerard et al. (1) to explain the role of soil moisture loss in hardpan formation in cultivated and virgin soils of the Lower Rio Grande Valley. Additional laboratory studies were conducted to clarify the proposed hypothesis. Results of the studies indicate that a slow rate of drying was an important factor in causing more intense close‐packing of soil particles or a greater degree of soil hardness.

The formation of a compacted layer in the Willacy fine sandy loam as affected by wetting and drying cycles and externally applied force to the surface at different moisture levels also was determined. The data indicate that rate of moisture loss, surface‐applied forces, wetting and drying cycles and temperature influenced the degree and/or rate of soil compaction. This soil was especially susceptible to compaction when the average moisture centent of the 0‐ to 7‐inch soil‐depth was 12.5%.
Influence of Vegetation Cover on Soil Moisture in Southeastern Ohio
Authors: Marston Richard B.
Published: July 2010

To obtain some information in the central United States of the effect of forest watershed vegetation on the amount of water available for streamflow, soil mositure to a depth of 36 inches was studied for 22 months in southeastern Ohio on oak, pine, broomsedge, brush, and cleared plots. Moisture content near the end of the dormant season was used as a measure of field capacity. It varied from 11.49 inches of water on the pine plots to 13.12 inches of water on the broomsedge plots. Generally, soil moisture declined throughout the summer and increased during the winter, but occasionally summer rainstorms were large enough to rewet the soil to field capacity. Late‐summer soil moisture deficits were greatest under oak and least under cleared, whether calculated on the basis of measured field depths or on the basis of equal volumes of soil. Water used in a 6‐month growing season ranged from 21 inches under cleared to 25 inches under pine. Additional water was withdrawn during the dormant season. The 2‐year average amount of precipitation required to refill the soil was 6.5 inches greater under pine than under broomsedge—broomsedge being the minimum cover practical here. Good opportunities exist in Ohio to affect streamflow and flood control through the manipulation of the forest cover.