bluuebunny/crossref_metadata_2025 huggingface dataset:
Fragipan Horizons in New York Soils: III. The Basis of Rigidity
Authors: Knox Ellis G.
Published: July 2010

Four fragipan horizons from Orange County, New York soils were studied to determine what materials or mechanisms are responsible for the strength of fragipans. Very fine‐grained material apparently holding the sand and silt particles together was identified as illite by optical and X‐ray diffraction methods. Experiments based on selective removal and destruction of possible bonding materials indicate that illite is responsible for a major part of the strength of the more typical fragipans studied, and that both illite and colloidal silica are involved in the strength of an extreme pan. Comparison of the strength of artificial briquets and natural clods further indicated that an important part of the strength of the pans studied is due to illite. It was shown that fragipans typically have high bulk density. The effectiveness of illite as a binding material in fragipans may be due to high bulk density, lack of effective structure, and special distribution of the clay.
Relationships of Soil Moisture Stress to Different Aspects of Growth in Ladino Clover
Authors: Hagan Robert M. , Peterson Maurice L. , Upchurch R. P. , Jones Luther G.
Published: July 2010

The relationships of soil moisture content or soil moisture stress to growth in Ladino clover have been investigated in containers under controlled environmental conditions and in field plots. Relationships involving the following aspects of growth or plant functioning are reported: (1) transpiration rate, (2) green weight production, (3) dry weight production, (4) dry matter percentage, (5) shoot elongation, (6) photosynthesis rate, (7) respiration rate, (8) chemical composition, (9) flower formation (number and size), and (10) seed production.

Dry weight production of vegetative material, photosynthesis, and respiration rates were not affected appreciably until the moisture content in the entire root zone approached the permanent wilting percentage. Green weight production and shoot elongation were reduced significantly when the soil moisture content fell into the lower half of the available range. Chemical composition, flower formation, and seed production were also influenced by moisture conditions within the available range.

The different relationships obtained illustrate that the increasing soil moisture stress experienced by Ladino clover as the readily available moisture is depleted does not have a uniform effect upon various aspects of its functioning and growth. Thus there is no one simple and general relation between soil moisture conditions and all aspects of plant functioning. Some plant processes are relatively insensitive to increasing moisture stress over the available range while others are distinctly affected. Such soil moisture‐growth relationships are also dependent upon plant characteristics, soil conditions, and climatic factors. Information on these relationships should suggest opportunities for more effective irrigation by considering both the soil moisture stress and the physiological stage of plant development in the timing of water applications.
Soil Crusting and Some Factors Affecting It
Authors: Lemos Petezval , Lutz J. F.
Published: July 2010

Physical studies were made of natural soil crusts and of the soils beneath them. Artificial crusts (briquets) were prepared by several methods and their modulus of rupture and bulk density were determined. The natural crusts had a much greater bulk density, a higher percentage of particles < 0.10 mm. in diameter, and a lower degree of aggregation than the underlying soil. The modulus of rupture of artificial crusts was increased by longer periods of drying at 105°C.; by slow drying (using lower temperatures); by compacting the dry soil in the briquet molds; by the beating effect of raindrops; and by puddling the soil before putting it into the molds. It was decreased by successive wetting and drying, but partial drying and rewetting gave results which varied with different soils. High modulus of rupture values were obtained with soils containing large amounts of soilt or total material < 0.10 mm. and, 2:1 type clay. Bulk densities were essentially the same: (a) for dry soil used in preparing briquets and the same type of soil beneath natural crusts in the field; and (b) for artificially prepared briquets and natural soil crusts.
A Study of the Validity of Laboratory Techniques in Appraising the Available Nitrogen Producing Capacity of Soils
Authors: Kresge C. B. , Merkle F. G.
Published: July 2010

There is urgent need for a laboratory procedure capable of determining the status of the soil nitrogen, one which will predict the ability of a given soil to quickly replenish nitrates removed by cropping and leaching. Such a method would be useful in evaluating soil management systems and in determining the need for nitrogenous fertilizers. A laboratory method is described involving incubation under controlled conditions for 12 weeks with bi‐weekly removal of nitrates produced. This method was found to be successful but time‐consuming. Distillation of ammonia from soils in the presence of alkaline permanganate gave recoveries which were well correlated with incubation results. Both procedures showed that from 200 to 400 pounds out of the 2,000 to 4,000 pounds of total nitrogen in soils are biologically active. With these methods it was possible to show that long continued use of manure leads to a backlog of biologically active nitrogen. Acidity likewise favors accumulation while excessive liming without proper provisions for maintenance depletes the active organic nitrogen supply. Prolonged acidity causes a decline in microbiological activity, permitting potentially active forms of organic nitrogen to accumulate. When this acidity is corrected, as in the laboratory procedure described or as in tier II of the Jordan plots, the yields are higher than on the corresponding less acid plots.

It is suggested that either method is quite useful in evaluating soils and soil management systems, but of questionable value in determining the nitrogen fertilizer requirements for the current year. Nitrate delivery to a given crop depends, not only upon the presence of easily ammonifiable organic nitrogen in the soil, but also upon the soil conditions prevailing at the moment. The available nitrogen requirement of a given crop depends upon the adequacy of other growth factors. A very poor correlation was obtained in the field between response to nitrogen and the quantity of easily nitrifiable organic nitrogen in those soils.
The Falling Water Table in Tile Drainage—A Laboratory Study
Authors: Luthin James N. , Worstell Robert V.
Published: July 2010

A sand‐filled tank 6 by 10 by 2 feet is used to study the distribution of hydraulic head and quantity of tile outflow during drainage.

A null‐type tensiometer for making rapid measurements of the hydraulic head is described.

The measurements of the transient phase of drainage known as the falling water table are compared to the theoretical development of Kirkham and Gaskell as well as Childs. The experiment demonstrates that the assumption used in the theoretical developments that the soil possesses a fixed drainage pore space leads to an incorrect solution. The shapes of the experimental water tables are similar to the theoretical shapes but the rate of fall is not accurately predicted by the theory.
Boron Deficiency, a Cause of Blank Stalks and Barren Ears in Corn
Authors: Berger K. C. , Heikkinen Toivo , Zube E.
Published: July 2010

In the greenhouse, corn plants, 14 days old, were transplanted to 1‐gallon, soft glass jars containing nutrient solutions. Boron levels were maintained at 0, 0.01, 0.05, and 0.25 ppm. One set of plants was grown for 3, 6, or 9 weeks at each of the boron levels, after which the boron was removed. One set at each boron level received boron to maturity. All other nutrients were maintained at adequate balanced levels.

Plants grown without boron or those at the 0.01‐ and 0.05‐ppm. boron level did not produce ears or had very poorly developed barren ears, depending on the length of time in the boron solution. Fully developed ears were produced at the 0.25‐ppm. concentration when maintained to maturity, but barren ears resulted when boron was removed earlier.

In field trials 15 pounds per acre of fertilizer borate was sidedressed in bands 18 inches wide with a hand duster, when the corn was a foot high, and resulting tissue analyzed.

Boron application resulted in increased yields and reduced the number of blank stalks, when present, on 11% of the fields tested.

It was concluded that: (1) a lack of boron can cause blank stalks and barren ears; (2), the supply of available boron must be continuous; and (3), the critical level of boron in the upper leaves appears to be in between 11 to 13 ppm.
Some Criteria for Capability Classification of the Soils of the Southern Great Plains of Texas
Authors: Coover James R. , Moldenhauer Wm. C.
Published: July 2010

The natural cloddiness of soils largely determines their susceptibility to wind erosion. As cloddiness decreases, greater amounts of cover and surface roughness are needed to reduce soil losses to insignificant amounts.

The use of a rotary sieve to help characterize soils for natural cloddiness is proposed. Procedures to be used are discussed. Results are reported from studies made of some of the extensive soil types of the southern High Plains of Texas.

A study of the climate of the area is reported also.

Yields of high‐residue‐producing crops are predicted for Amarillo fine sandy loam in several areas with small but significant differences in amounts of rainfall, using results of climatic studies and projection of yields from experiment stations. The correlation between grain yields and crop residues is discussed.

The natural cloddiness of soils, the residue needed to protect them, and the expected yields of high‐residue‐producing crops are proposed as additional criteria for determining the capability classification of the soils studied. The soils are classified, using the proposed method of classification.
Structural Implications of Moisture Retention by Clay‐Size Soil Materials
Authors: Kemper W. D.
Published: July 2010

At differential pressures, less than 1 atm., clay materials from soils retain much more water than calculations from Gouy theory would predict. Experimental evidence is shown which indicates that the excess water held in these materials is the result of a structure consisting of particle‐to‐particle bonds. The ability of this structure to resist pressures and by inference, the strength of the particle‐to‐particle bonds, can be increased by adding organic matter and decreased by increasing the amount of sodium on the exchange complex.
Proportionate Uptake of Soil and Fertilizer Phosphorus by Plants as Affected by Nitrogen Fertilization: II. Field Experiments with Sugar Beets and Potatoes
Authors: Grunes D. L. , Haise H. R. , Fine L. O.
Published: July 2010

Field experiments were conducted in North and South Dakota, with sugar beets and potatoes grown under irrigation, to determine the effect of nitrogen fertilizer additions on the relative availability of soil and fertilizer phosphorus to plants. The addition of nitrogen fertilizer generally increased the percent of the total phosphorus absorbed by plants from bands of concentrated superphosphate. The percent of the total plant phosphorus derived from the fertilizer tended to decrease later in the season.

Detailed studies with sugar beets at one location indicate that the percent of the total plant P coming from the fertilizer tended to increase with plant growth.
Magnesium Absorption and Utilization by Two Inbred Lines of Corn
Authors: Foy C. D. , Barber S. A.
Published: July 2010

Certain corn inbred lines are known to differ widely in the magnesium accumulating abilities of their leaves. The purpose of this investigation was to test the hypothesis that such differences in “magnesium feeding power” can be explained by differences in root properties. Corn inbred lines Indiana WF9 (high leaf magnesium) and Ohio 40B (low leaf magnesium) were selected for comparison.

Results indicate that low levels of magnesium in Ohio 40B leaves were not due to any lack of magnesium adsorbing or absorbing ability on the part of roots of this plant. Roots of Ohio 40B had a higher total cation‐exchange capacity and adsorbed magnesium more rapidly from solution than did those of Indiana WF9.

Ohio 40B leaves were always lower in magnesium content than those of Indiana WF9 whether plants were grown in sand culture or soil. Stems of Ohio 40B plants contained a higher percentage of magnesium than did those of Indiana WF9, and this magnesium was more difficult to extract with 1N ammonium acetate.

It is concluded that the low concentration of magnesium in Ohio 40B leaves is due, primarily, to an immobilization of magnesium in the stems of this plant.
Soil Aggregation by Microorganisms Following Soil Fumigation
Authors: McCalla T. M. , Haskins F. A. , Curley R. D.
Published: July 2010

The influence of autoclaving and of fumigation with eight chemical formulations upon microbial numbers in straw‐amended Peorian loess and the extent to which these treatments affect the degree of aggregation brought about by subsequently introduced inocula were determined. A mixed soil flora, Stachybotrys atra and a blank inoculum consisting of sterile salt solution, were compared. Only in the autoclaved soil was a mixed soil flora inoculum consistently superior to the blank inoculum in promoting aggregation of the Peorian loess. It was found that inoculation with S. atra could greatly increase the aggregation of fumigated Peorian loess in treatments where the fumigation was effective in reducing microbial numbers to a low level, and where the fumigant exerted little if any residual toxic effect upon the S. atra inoculum. Most promising of the fumigants tested were chloropicrin and Telone. The aggregation brought about by inoculation with S. atra in Peorian loess fumigated by appropriate amounts of either of these chemicals was approximately two‐thirds as high as that produced by the same organism following autoclaving of the soil material.
Soil‐Conditioning Properties of Modified Agricultural Residues and Related Materials: I. Aggregate Stabilization as a Function of Type and Extent of Chemical Modification
Authors: Smith H. E. , Schwartz S. M. , Gugliemelli L. A. , Freeman P. G. , Russell C. R.
Published: July 2010

The feasibility of producing soil‐conditioning agents from agricultural residues by chemical modification was investigated. Such reactions as xanthation, cyanoethylation, methylation, hydroxyethylation, sulfation, phosphorylation, acetylation, and oxidation were applied to wheat straw, corn stover, corncobs, bagasse, rice hulls, and their major components. From results of comparative reactions on cellulose, hemicellulose, and lignin, the major part of the soil‐conditioning activity of chemically‐modified agricultural residues was found attributable to the substituted cellulose fraction. The extent of substitution required to produce active products varies with the nature of the derivative but coincides in all cases with that required to give water‐soluble products. Within these limits the degree of polymerization has more influence on aggregate‐stabilizing activities than either the type or extent of substitution. Data on a number of microbial gums, plant polysaccharides, and starch derivatives are also presented.
Soil‐Conditioning Properties of Modified Agricultural Residues and Related Materials: II. Persistence of Soil‐Stabilizing Activity as a Function of Type and Extent of Modification
Authors: Schwartz S. M. , Freeman P. G. , Russell C. R.
Published: July 2010

Agricultural residues, cotton linters, several of their chemical derivatives, and other related products were tested in the laboratory for their in‐soil stability against microbial degradation for a period of 6 months in a controlled humidity cabinet. A modified Yoder wet‐sieving technique was used to test the stabilizing effectiveness of a given polymer incorporated into Miami silt loam soil.

Forty‐ to sixty‐mesh wheat straw, incorporated at a concentration of 0.5%, imparted greater stability to soil aggregates, following the first month of incubation at a temperature of 28° C., than did comparable applications of soybean and cotton stalks. Corn stover applications produced intermediate results. Twenty‐ to sixty‐mesh cotton linters at 0.5% concentration yielded increasingly effective soil aggregation during the first 3 months of incubation, reaching a maximum aggregation value of 93%. Chemically‐oxidized cellulose and corn starch showed surprising in‐soil stability throughout the 6‐month incubation period. In carboxymethyl cellulose samples, a degree of substitution (DS) of 0.7 or less was apparently insufficient to impart resistance to degradation by the microflora of the soil. However, carboxymethyl cellulose with a DS of 1.2 retained approximately 70% of its initial soilstabilizing activity over the 6‐month test period. In the case of hydroxyethyl and methyl cellulose, data are presented which tend to show that a high degree of substitution is not an adequate criterion of resistance to microbial degradation. Rather, the susceptibility of such polymers to enzymatic hydrolysis is apparently attributable to a lack of uniformity of substitution, resulting in a relative abundance of unsubstituted units in the cellulose chain.
Derivation and Application of a Method for Determining Minimum Recommended Rates of Fertilization
Authors: Pesek John , Heady Earl O.
Published: July 2010

Where the cost of fertilizer applied in the field can be expressed as the cost of application plus the cost of fertilizer, it is important to determine the rate which gives the highest net return per dollar invested. This rate describes both the economic minimum rate of fertilizer application and the lower limit that should be included in making agronomic fertilizer recommendations.

If yield increase, Y1, is expressed in the form of the quadratic equation, Y1 = sx + tx2, where x is the rate of fertilizer and s and t are constants; and the cost of fertilizer applied, Y2, is given by Y2 = m + rx, where m is the fixed application cost per unit area, and r is the price ratio of a unit of fertilizer to a unit of yield increase; then it is necessary to maximize the relationship
urn:x-wiley:03615995:saj2sssaj195803615995002200050014x:equation:saj2sssaj195803615995002200050014x-math-0001 by setting d/dx (Y1/Y2 − 1) = 0 in order to derive the rate of fertilization that will produce the highest profit per dollar invested in fertilization.

A direct solution of the quadratic functional relationship above can be made and leads to
urn:x-wiley:03615995:saj2sssaj195803615995002200050014x:equation:saj2sssaj195803615995002200050014x-math-0002 while a method of successive approximations may be used to solve relationships based on exponential functions of the Mitscherlich or Spillman form.
A Comparison of Ammonium Metaphosphate and Ammonium Orthophosphate with Superphosphate on the Yield and Chemical Composition of Crops Grown Under Field Conditions
Authors: Godfrey Curtis L. , Fisher Flake L. , Norris M. J.
Published: July 2010

Sweet Sudan and Iron‐Clay cowpeas were grown under irrigation in the field on a Lufkin fine sandy loam, an acid Planosol, and on a San Saba clay, a highly calcareous Grumusol (Rendzina). The plots were fertilized with 50‐30‐60 per acre, with the check receiving 50‐0‐60. The treatments consisted of ammonium sulfate, ammonium orthophosphate, ammonium metaphosphate, 20% superphosphate, muriate of potash, and calcium sulfate, applied in such a way as to give a valid comparison between the ammonium phosphates and superphosphate. The forage from one‐half the area of each plot was harvested 4 weeks after planting and the remainder at the end of 8 weeks. Forage yields and chemical composition were determined.

Crops at both locations responded to all P treatments, with the Sudan yields being increased about 90% over the check in contrast to only about a 10 to 15% increase by the cowpeas. The greatest yield response was by Sudan on the San Saba clay; the least response was by the cowpeas, also on the San Saba clay. All sources of P were about equal in their separate effect on crop yields at each location.

The P content of the separate crops was increased about the same by each source of P, but the P content was highest in the crops grown on the acid Lufkin fine sandy loam. The P content of the cowpeas grown on the San Saba clay was not appreciably affected by P additions.

The N, S and Ca levels in the forage were not affected by the P treatments, but were affected by location and species, and were greatly affected by the stage of maturity at harvest, the less mature forage being higher in these nutrients.
A Chromatographic Approach to the Leaching of Fertilizer Salts in Soils
Authors: Thomas G. W. , Coleman N. T.
Published: July 2010

The chromatographic theory of J. E. Walter was employed in the prediction of K distribution in four North Carolina surface soils representing extremes in texture and cation‐exchange characteristics. The soils were made homoionic with respect to Ca, Al, or Na and packed in glass columns. A small volume of KCl solution was applied, then leached with water. K within the column was determined at 1‐inch intervals and compared with the distribution predicted by the chromatographic equation.

In the cases of K‐Ca and K‐Al exchange an adaptation of the Gapon equilibrium constant combined with the Walter equation gave relatively good agreement with experimentally determined K distributions. K‐Na exchange did not behave as predicted unless the amount of K added was large in comparison to the amount of Na in the column.

Cation‐exchange capacity was an additional factor which influenced the retention of K by soils. Calcium soils adsorbed more K than did Al soils but this was confounded with an increase in “effective” exchange capacity with Casaturation. In general, the K distribution was described quite reasonably by the equation, but K retention at the top of the columns was consistently lower than predicted by theory.
Characteristics and Genesis of Low Humic Latosols
Authors: Sherman G. Donald , Alexander L. T.
Published: July 2010

The soils belonging to the great soil group of Low Humic Latosols have developed on basic crystalline rock materials in a semiarid to subhumid climate of subtropical and tropical regions having a pronounced dry period. The soil profiles of this group are characterized by the development of a weak A1 horizon in a solum which is predominantly kaolin clay. The solum is uniform in its chemical and mineral composition. The kaolin group make up > 50% of the clay fraction, together with iron oxides and with small amounts of gibbsite.

The silica/sesquioxide ratios of the clay fractions of the soils of the Low Humic Latosol group range from 1.1 to 1.7, with the majority of soils falling within the range of 1.30 to 1.55. The silica/alumina ratios range between 1.7 to 2.3, with an average of approximately 2.0.

The physical properties of the soils of the Low Humic Latosol group are clays which have the physical properties characteristic of silty clay loams due to their high content of kaolin and iron oxide.
A Chemical and Mineralogical Characterization of Selected Brunizem, Reddish Prairie, Grumusol, and Planosol Soils Developed in Pre‐Pleistocene Materials
Authors: Jarvis N. L. , Ellis Roscoe , Bidwell O. W.
Published: July 2010

A study was made of the role parent materials have played in determining the physical and chemical properties of four soil series of southeastern Kansas. The soils of this region are dominantly Brunizems; but Planosols, Grumusols, and Reddish Prairie soils also occur. These soils have developed in residuum and colluvium of sandstone, limestone, and shales. The soil series studied were the Taloka, Newtonia, Bates, and Summit—each sampled and studied in duplicate. The physical and chemical properties investigated were clay mineral composition, exchange capacity, total exchangeable cations, pH, percent organic matter, and particle size analysis.

Qualitative and semiquantitative estimations were made of the minerals occurring in the clay fractions of the soils and underlying parent materials. The predominant clay mineral in the Taloka, Newtonia, and Bates soils is montmorillonitic, whereas interstratified illitic and montmorillonitic clays are predominant in the Summit soils. Smaller amounts of quartz, illitic, kaolinitic, and vermiculite minerals are present in many of the clay fractions of the soils. The clay mineral contents of the developed soil profiles and their underlying parent materials were compared to determine the extent to which the clay minerals in the soil have been altered by weathering.
Calcium Phosphate Fertilizers: IV. The Relation Between Solubility in Soils and Availability Coefficients of Dicalcium and Fused Tricalcium Phosphates
Authors: Bouldin D. R. , Sample E. C.
Published: July 2010

The availability coefficient indexes per unit of P of 2 granule sizes of fused tricalcium phosphate (FTP), anhydrous dicalcium phosphate (DCPA), and dicalcium phosphate dihydrate (DCPD) were measured with 3 soils in greenhouse experiments. Availability coefficient indexes increased as granule size was reduced. Per unit of geometric surface area, availability coefficient indexes increased in the order FTP < DCPA < DCPD for all 3 soils.

The composition of solutions after 2 weeks' reaction between 1 g. soil and 1 g. of phosphate in 40 ml. of water was measured. The product of the concentration of P in these solutions and geometric surface area of the respective fertilizers explained 86% of the variation in availability coefficient indexes of the 6 fertilizers in the 3 soils.
Aluminum in Soils: III. A Comparison of Extraction Methods in Soils and Clays
Authors: McLean E. O. , Heddleson M. R. , Post G. J.
Published: July 2010

Samples of eight Ohio soils initially representing a wide range of extractable Al were moist‐equilibrated for 3 months with increasing increments of both H2SO4 and Ca(OH)2. Al was then extracted, using five salt solutions. Previously dialyzed bentonite, Putnam, and illite clays were extracted of their accumulated (and added) Al by direct treatment with salt solutions and by removal with cation‐exchange resin (Dowex 50‐8X, 20 mesh).

With low soil pH, NaCl, BaCl2, and NH4OAc at pH 4.8, all extracted comparable amounts of Al from the initialy more acid soils. However, soils less highly weathered initaly but made acid with H2SO4, released more Al to BaCl2 than NH4OAc at pH 4.8. With soil pH values above 5, more Al was removed by NH4OAc at pH 4.8 than either NaCl or BaCl2. Relatively little Al was obtained by extracting with either NH4OAc at pH 7.0 or triethanolamine + BaCl2 (Mehlich) solution regardless of soil pH. On the basis of extractability and solubility of Al and the possible effects on clay crystal stability, NH4OAc at pH 4.8 appeared to be superior as an extractant to the unbuffered neutral salts and to those buffered at pH 7.0 or above.

The extractable Al appeared to be largely exchangeable, since the amounts removed did not exceed the CEC of the soils whether 0.4 to 1.2 symmetry (S) concentration of H2SO4 was added, or 13 to 28 S of AlCl3 were equilibrated with the soils.

NH4OAc at pH 4.8, NaCl, and BaCl2 all extracted comparable amounts of Al from the acid clays and the resin after contact with the clays. In clays without Al added, more Al was extracted from Putnam with salt solutions than from the other clays; but less was extracted from it with resin. In contrast, much more Al was removed with resin from illite than from the other clays, and much more than with salts. The contents of extractable Al in bentonite and Putnam clays prepared from H‐resin and Ca‐resin increased with time but continued essentially equal in value, whether it was an H‐ or Ca‐clay.

The relative amounts of Al obtained from the resin by the various extractants depended upon the clay with which it had been equilibrated. Symmetry values for various cations showed the relative bonding of the cations by the resin was Al > Ca ≥ Ba > K > Na ≥ NH4 > H.
Characterization and Genetic Study of a Dennis and a Parsons Soil
Authors: Fanning Carl D. , Gray Fenton
Published: July 2010

The Dennis series is comprised of deep, well‐drained Prairie soils developed in slightly acid to neutral, silty, and clayey shales of the Pennsylvanian Age. Dennis develops in materials of intermediate texture on gently sloping, erosional uplands, whereas Parsons, a Prairie Planosol, develops in more clayey beds on gentle slopes and flats. They occur naturally associated and extensively in Oklahoma, Kansas, and Missouri.

A modal profile of each series was sampled in detail. Morphological, chemical, physical, and clay mineralogical studies were made on each subhorizon. The clay was separated into two fractions: 2 to 0.1µ (coarse clay) and < 0.1µ (fine clay). Analyses were made for ethylene glycol retention, nonexchangeable K, cation exchange capacity, differential thermal, and X‐ray diffraction. Computations were made for clay mineral composition.

Results show several times as much fine clay as coarse clay. In the Dennis the maximum clay accumulation occurs from 26 to 31 inches and in the Parsons from 22 to 28 inches. In the Dennis, coarse clay gradually decreases with horizonation and weathering, whereas in Parsons, it accumulates. Montmorillonitic‐type minerals dominate the fine clays of both profiles while kaolinitic and illitic types are dominant in the coarse clays.
The Effect of Oxygen Diffusion Rate and Applied Fertilizer on the Growth, Yield, and Chemical Composition of Peas
Authors: Cline R. A. , Erickson A. E.
Published: July 2010

The growth and nutrient uptake of pea plants were studied over a range of rates of oxygen supply and fertilizer levels. Oxygen diffusion rates, which varied from very low to those adequate for plant growth, as determined by platinum electrode techniques, were obtained by varying the depth of water table.

Three fertilizer rates were used to determine the extent to which fertilization might alleviate low oxygen supply. Nutrient uptake was measured by chemical analysis of roots and tops of the plants.

At very low oxygen diffusion rates, fertilizer had little effect on growth. Increasing the rate of O2 diffusion from 15 × 10‐8 g. cm.‐2 min.‐1 to 72 × 10‐8 g. cm.‐2 min.‐1 increased growth and nutrient uptake. High and medium fertilizer rates partially but not completely reduced the effects of low oxygen supply.
Inhibition of Root Growth and Cation Uptake by Antibiotics
Authors: Norman A. G.
Published: July 2010

Microbial products of an antibiotic nature produced in the rhizosphere may affect root growth and development. Twenty newer antibiotics have been tested to determine their activity in repressing elongation of roots of cucumber and growth of barley roots as measured by weight changes. Potency in repressing root elongation was found in most; 7 caused 50% repression at concentrations < 10 µg. per ml. Effects on conversion of barley seed endosperm to roots were demonstrated at similar but not identical concentrations. Effects on cation accumulation by excised 5‐day‐old barley roots were studied using various antibiotic concentrations in 10‐3M K2SO4. In no case was uptake found to be more sensitive than growth, and, with 4 of the 5 antibiotics studied, significant repression of uptake was observed only at concentrations many fold greater than those repressing growth.
A Method for Measuring Short‐Term Nutrient Absorption by Plants: III. Nitrogen
Authors: DeMent J. D. , Stanford George , Hunt C. M.
Published: July 2010

Roots of intact, N‐deficient oat plants proliferated rapidly in contact with both N‐fertilized and unfertilized soils, and recovery in top growth of 10 to 40 mg. of N applied as (NH4)2SO4 ranged from 67 to 38.5% after 7 days. Recovery by whole plants (tops + roots) ranged from 93 to 62%. During the same period, uptake from ureaform was about one‐third that of the soluble sources.

No differences in uptake from NaNO3, (NH4)2SO4, and urea in 7 days were found. Since selective absorption of NO3‐ and NH4+ ions by oat plants was not apparent under the experimental conditions, this crop is regarded as a suitable one for evaluating relative potential availability of N sources and factors influencing N uptake by the short‐term method.

N uptake from fertilizer with time described a sigmoid curve. The moisture equivalent was approximately the soil moisture level at which maximum N uptake occurred from Hartsells fine sandy loam and Webster silty clay loam. A highly significant linear correlation (r = 0.98) was found between N content of whole plant and tops based on combined analysis of data obtained with 2 soils, 3 N sources, 3 uptake periods, and 4 levels of N.
Distribution and Characteristics of Loessial Soil Parent Material in Northwestern Oregon
Authors: Theisen Arthur A. , Knox Ellis G.
Published: July 2010

Field study, mechanical analysis, and X‐ray diffraction analysis (of fine silt) were used to identify as loess a silty deposit bordering the Columbia River near Portland, Oregon. The loess material is 65 to 75% silt and pale brown. It commonly overlies reddish brown clay derived from Columbia River basalt. Quartz and feldspars were found in fine silt of the loess. Only quartz was positively identified in fine silt of the underlying material from basalt. Thinning with distance from the Columbia River and also from a point north of Portland indicates that the loess source was a former Columbia River floodplain, particularly the wide area north of Portland. Vertical discontinuities in particle size distribution and mineralogy, not coinciding with genetic horizons, suggested the existence of more than one period of loess deposition.
Some Tests of the Similar Media Concept of Capillary Flow: II. Flow Systems Data
Authors: Wilkinson G. E. , Klute A.
Published: July 2010

Previous work by the authors showed that a set of five sand fractions prepared by dry‐sieving and ranging in size from 104 to 250µ were essentially similar media on the basis of total porosity, moisture characteristic and capillary conductivity data. In the present work these same sand fractions were used in three kinds of flow systems. One was a system for drainage of an initially saturated column of the medium with a water table at the bottom. The drainage rate was measured. Another was a combined vertical infiltration and “field capacity” case in which water was allowed to penetrate the initially dry material to a scaled depth and then the supply of water was removed. Measurements of the rate of advance of the wetting front and moisture tension at a scaled position in the column were made. The third flow system involved drainage of a saturated column, followed by infiltration of a scaled amount of water and redistribution of the water in the column. The data from this sequence involved the hysteresis behavior of the porous media. Outflow and tension data from the three flow systems show that the similar media theory is valid.
Hydrogen and Calcium Ion Ratios in Dilute Equilibrium Solutions as Related to Cation Saturation
Authors: Webster G. R. , Harward M. E.
Published: July 2010

Soil samples were collected from field experiments so as to obtain a range in (Ca + Mg) saturation and pH for each soil type. The effects of equilibrating media were studied by comparing water and 0.01M CaCl2, each at 0.0003 and 0.0108 atm. partial pressure of CO2. Linear relationships were found for pH − ½ p(Ca + Mg) in the equilibrium solution vs. (Ca + Mg) saturation of the samples. Correlation coefficients ranged from 0.84 to 0.94 and were higher in every case than for pH of suspension vs. (Ca + Mg) saturation. The highest correlation was obtained with samples equilibrated in H2O and at the higher partial pressure of CO2. It was also noted that some soils equilibrated in water at the higher level of CO2 released Ca and Mg to solution more readily than other soils at the same degree of cation saturation. The fact that samples equilibrated in H2O revealed differences between soils in amounts of Ca + Mg released, whereas, samples equilibrated in CaCl2 solutions did not, was regarded as an important advantage for studying ion ratios in H2O solutions. Grouping of soils on the basis of their clay mineral content did not materially improve the correlations. The clay minerals in the soils studied were fairly similar, mostly vermiculite, kaolinite and chlorite, probably in differing amounts.
Forms of Phosphorus and Fixation in Soils
Authors: Cho Chai Moo , Caldwell A. C.
Published: July 2010

A determination of the main forms of P, P fixation, and a comparison of several methods of determining available P were made on several Minnesota soils.

Inorganic and organic forms of P were characterized and the inorganic fraction was further subdivided into aluminum phosphate, iron phosphate and calcium phosphate. Fractionation data of the inorganic P showed that iron and aluminum phosphates were abundant in acid soils while calcium phosphate was abundant in alkaline soils. In soils having a pH near 7, all three forms of inorganic phosphorus were about equally distributed, though slightly more iron and aluminum than calcium phosphate was present. Organic P agreed, in general, with the content of soil organic matter, but some deviation was noted.

The capacity of the soils to “fix” P from added KH2PO4 was observed. It was found that the P‐fixing capacity of soils increased with departure from a pH near neutrality.

Bray No. 1 and 2, NaHCO3, citric acid, Morgan's, and water‐solubility methods of determining available P were compared. Available P in the soils varied greatly depending upon the extraction procedure used. Generally the amounts of available P as determined by methods employing strong acids were higher than those using weak acids. Correlation analysis was carried out on forms of P and the amount of P as determined by the various quick methods.
Aluminum in Soils: IV. The Role of Aluminum in Soil Acidity
Authors: Heddleson M. R. , McLean E. O. , Holowaychuk N.
Published: July 2010

Samples of soils representing a wide range of pH and extractable Al were treated with increments of acid and base and incubated for 3 months. The extractable Al and exchange acidity were measured. Samples were also treated with increments of AlCl3 and measurements of extractable Al and exchange acidity again made. Various resin titrations were made in order to compare the reaction of TEA with both Al and H, and to observe the acid properties of Al ions.

An increase in both extractable Al and exchange acidity was found following treatment of soils with acid. The increase was much greater in mildly acid soils than in highly acid samples. The increase in extractable Al and exchange acidity was generally of the same order of magnitude. Acid, strongly weathered soils were found to adsorb much less Al than did neutral, less weathered soils treated with increments of AlCl3. Apparently Al was near equilibrium in acid soils but not in mildly acid or neutral samples.

Al resin was shown to titrate similar to a weak acid while H resin titration more nearly resembled a strong acid. Titration of Al resin with KOH in absolute alcohol indicated that hydrolysis was necessary for Al to exhibit acid properties. Results show that soil acidity is composed of both H and Al and that measurement of acidity by TEA measures at least part of the Al.
Characterization of Exchange Reactions of Strontium or Calcium on Four Clays
Authors: Heald Walter R.
Published: July 2010

To a series of calcium or strontium saturated clays suspended in 50 symmetry concentrations of the saturating ion, variable amounts of Sr85Cl2 or Ca45Cl2 were added. From the radiochemical analysis of the clay at equilibrium, the amount of exchange was determined.

Plotting the data as [Cation‐Clay]/[Cation‐Solution] vs. [Cation‐Clay] yielded a curved line composed of at least two adsorption isotherms. This is interpreted to mean two independent sites of adsorption or that two mass action equations are necessary to describe the system.

Following the cation desorbed by tracer technique resulted in almost identical curves as when the adsorbing cation was followed. This evidence showed that no precipitation or reaction other than the one described took place. Also, the sites were shown to be independent by introducing a third cation such as barium. Barium ions at an appropriate concentration prevented the adsorption of the cation being studied on the “tight site” but had no effect on the adsorption of the cation on “loose site.”

The two sites were separated graphically and labeled “tight” and “loose” sites according to the bonding energies for the cation being studied. An apparent equailibrium constant was calculated from the slope of the “loose site.” The slope of the “tight site” could not be determined accurately enough to calculate an equilibrium constant, being less than 1% of the exchange capacity. Strontium is adsorbed more tightly than calcium on either site, but the difference becomes less as the exchange capacity of the clay decreases.

It was necessary to define the data in terms of two mass action equations if the exchange reaction is to be stoichiometric at either site. Using one equation to compare the adsorption of Sr and Ca resulted in considerable hysteresis, largely due to the influence that the sites have on each other.
Influence of Long‐Time Fertility Management Practices on Chemical and Physical Properties of a Fargo Clay
Authors: Young R. A. , Zubriski J. C. , Norum E. B.
Published: July 2010

Laboratory phases of a study to evaluate the effectiveness of various long‐time management practices in maintaining fertility of Fargo clay are reported. Soil samples which had been taken at the beginning of the trial in 1913 and those taken in 1952 and 1953 were used for chemical analyses. Physical measurements were made on samples taken from 1954 to 1956. Analyses included total N, organic C, pH, cation‐exchange capacity, exchangeable cations, extractable and organic P, nitrification capacity, aggregation and aggregate stability by wet‐sieving, porosity, density, and hydraulic conductivity. Soil organic C and N declined 27% in check plots and 20% in residue or manure plots. Phosphorus‐treated plots suffered slightly greater loss than similar plots without P. Lime had no effect. C/N ratio did not change. Nitrification capacity correlated with total N content. Extractable P declined appreciably in check plots, less in residue and manure plots, and increased in P‐treated plots. Organic P losses were similar to those of organic carbon. In all plots, CEC declined slightly. pH increased slightly in nonlimed plots and moderately in limed plots. Physical measurements did not reveal any important differences in structural properties of Fargo clay that could be related to past management practices.
Worm‐Worked Soils of Eastern South Dakota, Their Morphology and Classification
Authors: Buntley G. J. , Papendick R. I.
Published: July 2010

Soil survey field mapping of Brookings County, South Dakota, showed extensive areas of soils with nearly complete destruction of zonal profile horizonation as the result of mixing by intensive worm‐working. These worm‐worked profiles have moderately thick, black, recognizable A1 horizons, grading through completely mixed horizons of B2 with A1, A1 with B2, B3ca with B2, B2 with B3ca, or other combinations of horizons, before grading into the comparatively unmixed parent material. Laboratory analyses were made on some of these profiles in conjunction with the survey and with this study. Field studies were later extended, through the use of transects, to the surrounding areas of South Dakota. From these transect studies the area of occurrence of these soils was delineated. Worm‐worked soils were found in Wisconsin tills ranging from Iowan through Mankato in age and also in Wisconsin loess mantling the Iowan and Tazewell tills. These profiles resemble in some characteristics the “thick” or “fat” Chernozem of Europe. The name “Vermisol” is suggested to represent a more specific group classification for grassland soils displaying the unique profile characteristics associated with intensive worm‐working.
Extraction of Free Amino Acids from Soil
Authors: Paul E. A. , Schmidt E. L.
Published: July 2010

Alternatives to extraction with ethanol were examined in order to obtain more effective removal of free amino acids from soil. Ba(OH)2 was a promising extractant and proved to be very effective in recovering a mixture of 17 amino acids that had been added to soil. Resolution of the extract by elution chromatography was followed by colorimetric analysis; 73 to 121% of the acidic and neutral components of the mixture and 36 to 41% of the basic amino acids were recovered. A second extraction procedure, based on the use of NH4OAc, was developed to avoid any slight hydrolysis of amino acid polymers that may have occurred during preparation of Ba(OH)2 extracts. The NH4OAc extraction procedure was 31 to 83% effective in the recovery of added amino acids from soil. When both extraction techniques were applied in preliminary trials to characterize the free amino acids fraction of a soil, the NH4OAc extraction was considered the better. Both NH4OAc and Ba(OH)2 extractions yielded many more kinds of free amino acids in concentrations 5 to 25 times greater than that reported earlier in comparable studies using ethanol extraction.
Soil Potassium Reactions as Related to Clay Mineralogy of Selected Kentucky Soils
Authors: Cook M. G. , Hutcheson T. B.
Published: July 2010

Clay mineralogy was related to soil K reactions of Heitt, Eden and Maddox series, representative soils of high K‐supplying power; and Maury, Bedford and Tilsit series, representative soils of low to medium K‐supplying power.

Clay fractions of Heitt, Eden and Maddox soils contained more illite than Maury, Bedford and Tilsit clay fractions; thus illite is the probable seat of K‐supplying power.

Effects of drying the soils on exchangeable K levels were investigated. Upon drying, fixation was observed when the initial, field‐moist level of exchangeable K was relatively high; release occurred when the initial level was low.

The 14Å. vermiculite spacing contained by soils of high K‐supplying power was easily collapsed to 10Å. by K saturation and 100° C. heating, whereas that spacing of soils of low K‐supplying power was affected little by K saturation, requiring 300° C. or higher heating for closure. At least two possible explanations could account for the differences in collapsibility: (a) differences in magnitude, location and origin of interlayer charge; and (b) presence or absence of nonexchangeable Al in interlayer positions.
Activity Measurements in Water and Clay‐Water Systems With Tertiary Electrodes
Authors: Uehara Goro , Mortland M. M.
Published: July 2010

A tertiary amalgam electrode was utilized in the measurement of CaCl2 and Ca++ activities. Activity coefficients from electromotive force data compared favorably with those in the literature. The relative influence of various metal ion salts on the CaCl2 and Ca++ activities followed the sequence Rb ≥ Mg > K > Na > Li for both kaolinite and Wyoming bentonite. The activities of CaCl2 and Ca++ in bentonite‐kaolinite mixtures differed from predicted activity values based on pure clay systems.