bluuebunny/crossref_metadata_2025 huggingface dataset:
Ion Activities and Osmotic Pressures in Clay‐Water Systems
Authors: Coleman N. T. , Jakobi W. J.
Published: July 2010

Osmotic pressures of H‐, Na‐, and K‐bentonite suspensions were measured with an Adair osmometer. Measurable osmotic pressures were observed, but the values were quite small, ranging from 0.6 cm H2O for 1% Na‐bentonite to 4.2 cm H2O for 4% H‐bentonite. The ion activity difference across the osmometer membrane, calculated from the membrane potential and the ion concentration on the solution side, was large. The ionic osmotic pressure difference across the membrane, from the van't Hoff approximation, was much larger for all systems than was the observed osmotic pressure, leading to the conclusion that the membrane potential cannot be regarded as a measure of an electrostatic potential difference between a clay suspension and its equilibrium dialysate.

Electrolyte mean activities of KCl solutions were consistently slightly smaller than in 2% K‐bentonite suspensions of the same normality of KCl. Mean activities of KCl in the clay suspensions were much smaller than K+ activities measured with a membrane electrode‐saturated calomel electrode cell.

The osmotic pressure data and potentiometric data are interpreted as indicative of a spurious potential at a clay‐salt bridge junction.
Reaction of Phosphate with Kaolinite in Dilute Solution
Authors: Russell Glenn C. , Low Philip F.
Published: July 2010

A typical adsorption curve obeying the Freundlich equation was produced by the adsorption of phosphate on kaolinite. By saturating the exchange complex of the clay with aluminum ions, phosphate adsorption was markedly increased indicating that exchangeable aluminum will react with the added phosphate. Reflectance‐wave length curves of aluminon‐treated kaolinite revealed the presence of aluminum ions or hydrous aluminum oxide films on the surface of natural kaolinite. This reactive aluminum was reduced by extraction of the clay with aluminum‐complexing reagents. The adsorption of phosphate was also reduced by the same treatment. Phosphate adsorption was further reduced by the presence of an aluminum complexing reagent in the phosphate solution reacting with the extracted clay. It was concluded that adsorbed aluminum precipitates the phosphate as an aluminum phosphate on the kaolinite surface.
Effect of Tillage Practices Upon Intake Rates, Runoff and Soil Losses of Dry‐Farm Land Soils
Authors: Diebold C. H.
Published: July 2010

During the growing season, serious losses of water and soil occur on extensive areas of dry‐farm land in New Mexico, Colorado, and Utah due to poor surface soil condition and to the presence of tillage pans, usually at depths of from 3 to 8 inches. Studies were made of runoff and soil losses from plots containing 30½ square feet. Simulated 10‐year storms were applied to these plots to evaluate tillage practices.

The following conclusions were made during these studies. Chiseling through the tillage pan every 12 inches reduced both soil and water loss more than cultivation with either sweeps or one way disks on deep, medium textured soils. Excessive runoff and erosion occurred where the chisel spacing was 5 feet, or where chiseling, sweeps, and oneway did not penetrate through the tillage pan.

Runoff from snow on frozen ground causes serious losses of soil and water in northern Utah. A frozen watershed that had been chiseled lost 0.61 inch less runoff than a similar watershed that had been cultivated with a oneway disk. Medium textured soils high in silt, when frozen at high moisture contents, had slow intake rates, irrespective of tillage practices.
Correlation of Soil Moisture and Cotton Yields
Authors: Burnett Earl , Fisher C. E.
Published: July 2010

In a 22‐year experiment, the correlation between the yield of lint cotton and available soil moisture at three sampling dates and six sampling depths was determined. The most significant correlation was found to exist for the available moisture in the soil on May 20, the optimum date for planting cotton. The correlation between yield and soil moisture was slightly lower for determinations made on June 20, and much lower for those made on April 20. Eliminating the moisture content of the first foot of soil, which fluctuates greatly because of weed growth and evaporation, improved the relationships on all dates. The relationships were not improved by including the moisture in the fourth and fifth feet of soil — an indication that in most years the cotton plant obtains most of the water necessary for growth from the second and third feet of soil. The importance of deep moisture storage in cotton production under sub‐humid and semi‐arid conditions is discussed.
Influence of Factorially Combined Levels of Cations and Nitrate Ions Adsorbed on Ion‐Exchange Resins on the Nutrient Absorption by Plants
Authors: Welch H. V. , Wallace A. , Mueller R. T.
Published: July 2010

The interaction of different levels of cations and nitrate nitrogen adsorbed on synthetic exchange resins upon nutrient absorption by plants was studied in a pot experiment. A factorial design of three levels of cations and three of N was used. Ca, Mg, and K were supplied at the same ratio at all three levels and P and S were unvaried. Three successive plantings were made. These were lemon cuttings, oats, and oats and radishes together. These two species were seeded together because their roots have different cation‐exchange capacities. The adsorbed ions proved to be an excellent source of nutrients for the plants. A balance sheet was prepared for all nutrients removed by the crops. Yields were limited in the second and third crops by both N and cation levels. K proved to be the limiting cation. Ca and Mg absorption was depressed as the cation level increased because of increased K uptake. The m.e. of cations per 100 grams dry plant weight increased with increasing cation levels for two oat crops, but was more constant for a lemon and a radish crop. Increasing N levels resulted in increased N and in an increased total anion uptake, but resulted in depressed P and S uptake. The level of adsorbed N did not appear to influence the total cation content in lemon and radish, but there was a slight effect on oats, particularly in the first crop. The level of cations did not appear to influence the N or the m.e. sum of anions in the plants beyond the differences caused by yield variations. The cation‐anion ratios in the plants were much narrower than those in the nutrient medium. Increases in N tended to result in increased K and Mg contents in the lemon cuttings and in oats when the supply of cations was high. When the cation level was low for oats, and at all levels for radishes, increases in N tended to result in decreased K. The latter effect was partly related to K depletion at the low cation levels combined with yield increases due to N.
Chemical Characteristics of Certain Profiles of Alluvial Soils in the Lower Mississippi Flood Plain
Authors: Driskell B. N.
Published: July 2010

The soils of the lower Mississippi Flood Plain are derived from the Mississippi or Red River depositions. In certain areas these have been mixed. The soil constituents have been modified or changed entirely by time and environment.

Profiles from the Iberia, Buxin, and Baldwin soil series were studied. The comparative results indicate that the Iberia was highest in exchangeable calcium and base saturation. Exchangeable magnesium and potassium were highest in the Buxin. Baldwin was lowest in total cation exchange.

The Buxin series contained larger quantities of the oxides of iron, aluminum, magnesium, potassium and sodium as shown by analysis of the clay fraction than Iberia or Baldwin. Iberia was highest in calcium oxide and Baldwin highest in silica. The content of silica increased with depth for all profiles.

The ratios of SiO2/R2O3, SiO2/Al2O3, SiO2/Fe2O3, SiO2/total bases, and carbon‐nitrogen varied with the soil series, depending upon the source of materials.

X‐ray patterns indicate that montmorillonite and illite were the predominating clay minerals and varied with the particular series. The Iberia clay contained more montmorillonite than the Baldwin or Buxin, especially in the A and B horizons.

The characteristic study of these series has been of value in establishing fundamental facts that can be used in soil classification. It is evident that these series generally differ in chemical and mineralogical properties; yet, certain similarities exist between certain profiles of different series.
Effect of Various Exchangeable Cation Ratios on Kinds of Fungi Developing during Decomposition of Organic Residues in Soil
Authors: Martin J. P. , Aldrich D. G.
Published: July 2010

Soils varying widely in exchangeable Ca, Mg, K, Na and H ratios were prepared from Yolo loam and Hanford sandy loam soils. The effect of these ratios on the kinds of soil fungi developing during the decomposition of organic residues in the soil was followed at various intervals over a 200‐day incubation period.

In general, the nature of the organic material added to the soils exerted a greater effect on the kinds of fungi developing than did the exchangeable cation ratios. In the absence of organic residues, the fungus population remained essentially the same in all soils over the entire incubation period. Upon the addition of organic residues, Penicillium nigricans, which was present in high concentrations in the check series (no organic residues), became increasingly dominant in the most‐acid soils. With few exceptions, other species became dominant in all other soils. The kinds of fungi becoming dominant depended on the nature of the organic residue added. The dominant species included Chaetomium sp., Cunninghamella bertholletiae, Fusarium spp., Monotospora brevis, Mucor spp., Sepedonium chrysospermum, Sporotrichum sp., Stachybotrys atra, and Stysanus stemonites. Some species developed quickly in large numbers and remained dominant for the remainder of the incubation period. Others developed in high concentration, then rapidly diminished in numbers or disappeared.
Simple Diffusion Well for Measuring Soil Specific Diffusion Impedance and Soil Air Composition
Authors: van Bavel C. H. M.
Published: July 2010

Straight, cylindrical tubes, open at the lower end and inserted into the soil can serve a dual purpose. Measurement of the re‐entrance of oxygen into the tubes after they have been flushed with nitrogen permits a calculation of the specific diffusion impedance of the soil. Charts for computing purposes are given. Measurement of the composition of the gas in the well, after a suitably long equilibration time, is a convenient means for measuring the composition of the soil air at the depth of insertion of the well.

The physical and mathematical aspects of the method are briefly presented and experimental proof is offered for the formulas that are derived.
The Relationships among Corn Yields, Leaf Composition and Fertilizers Applied
Authors: Viets F. G. , Nelson C. E. , Crawford C. L.
Published: July 2010

The purpose of this study was to determine the effect of fertilizer application on corn yields and the composition of certain leaves, and the relationships between leaf composition and yields. Three experiments differing in details were conducted under irrigation with hybrid Iowa 939 corn in central Washington.

Leaves were selected at several growth stages, but the second leaf below the ear collected at silking was studied most intensively. Analyses were made for total N, P, Ca, Mg, K, and Mn and for P soluble in 2% acetic acid. Only N increased yields significantly; K and P applications did not. Calcium nitrate was least effective of the five N sources used. Total N content of leaves selected prior to silking gave lower correlations with yield than those selected at silking. Yields were highly positively correlated with both N and total P contents of leaves selected at silking, and total P and N contents of leaves were also highly correlated. Partial regression analysis showed that leaf N was probably the dominant determinant of yield, but that the leaf P content was sometimes important.

For the three experiments the regression coefficients of yield on leaf N content were not significantly different, but the intercepts were markedly different.

In one experiment, yields declined 15 bushels per acre for each leaf per plant showing N deficiency symptoms at silking. The minimum leaf N percentage associated with no evidence of the characteristic tip firing of N deficiency appears to be far below the reported critical N concentrations for maximum yield.

Ammonium sulfate produced the highest leaf P and K contents and the lowest Ca and Mg contents in comparison with Ca(NO3)2 and NH4NO3 as N sources. The sum of the determined cations Ca, Mg and K in leaves selected at silking tends to be a constant at about 100 m.c. per 100 gm.

Phosphorus soluble in 2% acetic acid was a linear function of and equal to about two‐thirds of the total P over a wide range of total P in the leaves.
Soil Factors Affecting Molybdenum Uptake by Cauliflower
Authors: Gammon N. , Volk G. M. , McCubbin E. N. , Eddins A. H.
Published: July 2010

Molybdenum deficiency of cauliflower (whiptail) has been observed on the acid (pH 4.2 to 5.0) flatwoods soils of Florida. Considerable differences have been noted between cauliflower varieties in their development of molybdenum deficiency symptoms on these soils. Direct applications of molybdenum with and without lime were used as means of correcting the deficiency. Soil and plant analyses indicate that these soils can supply an adequate amount of molybdenum for plant growth by increasing the soil pH.

The growing of cauliflower seedlings in acid, heavily fertilized soils limits the molybdenum taken up by the plant. These plants are set in the field in acid soils made even more acid by current fertilization. The plants with low molybdenum content and root systems restricted by transplanting are set in a soil with a low molybdenum supplying power. These conditions result in a temporary molybdenum deficiency in the plants. Subsequently, this deficiency becomes apparent when the damaged buds develop and the whiptailed leaves appear. As the roots grow and the acidity from the fertilizer dissipates, conditions become more favorable for molybdenum uptake by the plants. The degree of bud damage and the subsequent availability of molybdenum to the plants will be major factors in determining the degree of recovery and production of marketable heads by the plants. Failure of the leaves to develop chlorosis is further evidence of the temporary nature of the deficiency.

Because molybdenum does not readily leach, there could be a possible danger to livestock if the fields were converted to pastures, following repeated applications of molybdenum for correction of whiptail. The molybdenum supply of the soils is low but probably adequate under favorable soil pH. The safest way to avoid molybdenum deficiency under these conditions is to grow varieties less susceptible to whiptail; to lime soils to as high as is commensurate with other crops grown in the area (pH 5.5 for potatoes); to lime seed beds to pH 6.0 to 6.5; and to use fertilizers containing fewer materials forming temporary acidity, especially in seed beds.
The Movement of Soil Moisture in Response to Temperature Gradients
Authors: Taylor Sterling A. , Cavazza Luigi
Published: July 2010

Using an air gap technique, it has been shown that the flow of moisture in the soil from warm to cool regions might occur largely in the vapor phase. This is accompanied by a return flow of liquid water in response to an induced flow potential gradient. The use of wire screens to make air gaps interferes with this process.

The measured diffusion coefficient for vapor flow was higher than had been expected from diffusion data, but was substantially in agreement with that of other workers. The reasons for this high diffusion coefficient might be that the diffusion of moisture and heat is coupled in soils; the phenomena of surface migration and molecular hopping of adsorbed water might also cause this increase.

The factors having greatest effect on the moisture distribution in continuous soil columns in a closed system are: (1) the diffusion and the convection of vapor or some related processes; (2) the evaporation and condensation occurring in the two end regions of the cylinders; (3) the hydraulic conductivity of the soil.

The thickness of the air gap in broken columns influences the amount of water that will be transferred in the vapor phase and must be considered whenever an air gap is used to prevent fluid flow.

The existence of two distinct drying and wetting moisture characteristic curves has been verified, and they play an important part in determining the liquid flow of moisture in the soil. The influence of this factor as well as the reason for the large vapor transfer need further study in relation to the transfer of soil moisture.
Conductometric Titration of Soils for Cation‐Exchange Capacity
Authors: Mortland M. M. , Mellor J. L.
Published: July 2010

The reaction of barium‐saturated soil with the sulfate anion of a standardized titrating solution to form insoluble barium sulfate is utilized for determining soil cation‐exchange capacity. The endpoint of the reaction is determined by conductometric titration. Specific conductance remains comparatively constant while the barium on the exchange complex is being titrated. After the barium has been titrated, conductance increases as increments of the titrating solution are added. The endpoint of the reaction is obtained from the intersection of the two linear portions of the curve. Cation‐exchange capacity data obtained by this method are compared with data obtained by other methods on the same soils.
Decomposition of the Soil Conditioning Polyelectrolytes, HPAN and VAMA in Ohio Soils
Authors: Mortensen J. L. , Martin W. P.
Published: July 2010

C14 labeled synthetic polyelectrolytes, HPAN (hydrolyzed polyacrylonitrile) and VAMA (a copolymer of vinyl acetate and maleic anhydride) were added to Brookston silty clay loam and Hoytville silty clay respectively, to determine the extent of decomposition of these compounds. In an incubation period of 130 days, radioactive carbon dioxide equivalent to 2.74% of the added HPAN and 0.20% of the added VAMA was produced as a result of microbial metabolism. The addition of 1% carbon as rye grass increased the decomposition of VAMA to 0.30%.

Microbial activity, as evidenced by CO2 evolution, was increased by polyelectrolyte treatment and a correlation between total carbon loss and decomposition of polyelectrolyte is suggested. Biochemical aspects of polyelectrolyte decomposition in soil substrates are discussed.
Soil Aggregation as Influenced by Microbial Gums, Level of Fertility and Kind of Crop
Authors: Rennie D. A. , Truog Emil , Allen O. N.
Published: July 2010

A study was made of the effect on soil aggregation of microbial gums produced in vitro and in soil. Attention was also given to the effects of fertility treatments, kind of crop, and season on the aggregation of Spencer silt loam.

The bacterial polysaccharide synthesized by Agrobacterium radiobacter in pure culture had a marked aggregating effect when added to Spencer and Miami silt loams. Addition of as little as 0.02 gm. of this gum to 100 gm. of soil caused a 50% increase in aggregates > 0.1 mm. in diameter. The gum content of numerous samples of Miami and Spencer silt loams correlated well with their respective levels of aggregation. The addition of extracted soil gum to a poorly aggregated soil increased significantly the degree of aggregation.

Undecomposed pulverized plant residues added to soil increased the gum content to a maximum in six days. The maximum percentage of aggregates > 0.5 mm. in diameter was not reached until the twelfth day.

In a four‐year rotation of corn, oats, and two years of alfalfa‐brome on plots which were variously limed and fertilized, increases in percentage of soil aggregates occurred at pH 6.0, 6.5, and 7.5 as compared with the aggregation level of the check plot (pH 5.5). High levels of available phosphorus and potassium as compared with low levels promoted aggregation. In general, structural deterioration began under corn and continued until the following crop of oats attained considerable growth. Thereafter improvement continued and reached a maximum during the second year of hay.

Seasonal variations in soil aggregation occurred on all plots, irrespective of soil treatment or crop, and was characterized by a gradual increase in percentage of water‐stable aggregates during the spring and summer followed by a sharp decline in September.
Boron Materials of Low Solubility and Their Use for Plant Growth
Authors: Wear John I. , Wilson Clarence M.
Published: July 2010

Three sources of boron including high‐grade Fertilizer Borate, Colemanite and Howlite were compared as to their water‐soluble boron contents, effect on plant growth and movement within the soil profile.

Based on mill‐run samples, the water‐soluble boron in Fertilizer Borate was 5 times greater than in Colemanite and 25 times greater than in Howlite.

Particle size had only a slight effect on the water‐soluble boron recovered from Fertilizer Borate, but for Colemanite and Howlite the amount of water‐soluble boron recovered was 6 to 8 times greater for finer than 80‐mesh material as compared to coarser than 10‐mesh material. This indicates the importance of particle size in controlling the rate of solubility of the more slowly soluble sources of boron.

Although the water‐soluble boron in Fertilizer Borate, Colemanite and Howlite was in the ratio of approximately 1:5:25, the boron contents and toxicity symptoms of turnips and soybeans grown in the greenhouse in Norfolk loamy sand indicated a requirement of about twice as much Colemanite as Fertilizer Borate and 2 to 3 times as much Howlite as Colemanite to produce the same degree of toxicity.

Results of the field leaching study on Norfolk loamy sand indicate that high‐grade Fertilizer Borate leached out of the topsoil very rapidly and collected in the lower zones of 8 to 16 and 16 to 24 inches. Twelve months later most of the water‐soluble boron had been leached past the 2‐foot depth. Howlite leached out of the topsoil slowly; the concentrations of water‐soluble boron remained fairly constant for the 6 and the 12‐month periods. Colemanite was found to be intermediate between the highly soluble sodium borate and the less soluble borosilicate from the standpoint of loss by leaching.
Yields of Cotton and Other Crops as Affected by Applications of Sulfuric Acid in Irrigation Water
Authors: Christensen P. D. , Lyerly P. J.
Published: July 2010

Effects of sulfuric acid on crop yields and on some physical and chemical properties of a calcareous soil were investigated in a field experiment from 1947 through 1952. On cotton plots, the treatments consisted of applications of irrigation water containing no acid (pH 8.3), water acidified to pH 6, and water acidified to pH 2.3. Cotton was grown five season followed by sesbania the sixth season. A test on alfalfa was established using irrigation water not acidified and water acidified to pH 4. Alfalfa was grown for 3 years. The fourth year the alfalfa was plowed under and a crop of corn was raised.

Cotton yields on the acid plots relative to the checks became progressively higher (with two exceptions) from one year to the next; however, in only one year (1950) were differences in yield statistically significant. With sesbania following cotton, highly significant yield increases resulted from the high acid treatment.

Alfalfa yields on the acid plots became progressively greater relative to the non‐acid plots, but yield differences were not significant.

In cotton leaves, the acid treatments resulted in increased uptake of magnesium, sulfur, and phosphorus, but the increases were probably not significant. Uptake of sodium, potassium, calcium, manganese, and iron were not appreciably affected.

In sesbania, the acid treatments did not significantly alter the uptake of any of the plant nutrients determined. There was some indication, however, that the uptake of sodium and iron was reduced by the acidification.

The results of this study support the view that soil acidification on calcareous soils may improve the soil physical conditions and result in increased yields, particularly in some crops. The application of acid in the irrigation water did not prove to be economically feasible.
The Effect of Magnesium upon the Growth and the Phosphorus Content of Soybean Plants
Authors: Webb J. R. , Ohlrogge A. J. , Barber S. A.
Published: July 2010

An investigation was made of the effect of magnesium upon the growth, the phosphorus absorption and translocation, and the cation content of soybean plants. The plants were grown in sand culture in the greenhouse, and the main treatment consisted of removing magnesium from the nutrient medium for various periods during the life cycle of the plants.

The removal of magnesium from the nutrient medium for any of seven different periods of 21 to 121 days during the life of soybean plants reduced growth, but its absence early in the life of the plant caused a greater reduction than its absence later in life.

Omission of magnesium from the nutrient solution did not retard phosphorus absorption but did have a significant effect upon the movement and final location of phosphorus in the plants. The chemical composition of the component parts of the mature plants revealed that the magnesium deficient plants contained a higher percentage of phosphorus in the vegetative organs and a lower percentage in the seeds than normal plants. A definite positive relationship existed between the magnesium and phosphorus content of the seed, and a definite negative relationship between the content of these two elements in the leaflets. This finding offers support to the theory that magnesium may function as a carrier of phosphorus in plants.

The magnesium deficient plants absorbed slightly larger amounts of calcium and potassium on a percentage basis.
Yield‐of‐Phosphorus Curves
Authors: Dean L. A.
Published: July 2010

This paper embraces a study of the curves relating the total phosphorus absorption by plants with the fertilizer phosphorus additions (yield‐of‐phosphorus curves) and may be summarized as follows:

For applications up to 160 pounds P2O5 per acre mixed throughout the soil, the “normal” yield‐of‐phosphorus curve was found to be an ascending straight line. Extrapolation of the yield‐of‐phosphorus curves to the point of intersection with the X axis gave a measure of the available soil phosphorus which approximated the ‘A’ value. Estimates obtained by extrapolation of yield curves gave values about half has large. The slope of the yield‐of‐phosphorus curves is to a degree influenced by the phosphate fixation processes.
Compression Studies of Illite Suspensions
Authors: Bolt G. H. , Miller R. D.
Published: July 2010

It can be shown that the classical Gouy‐Chapman theory of the electric double layer formed on planar surfaces provides and acceptable means of predicting the “osmotic” pressure of clay suspensions for various particle spacings and electrolyte contents.

A compression apparatus was designed for the measurement of the swelling pressures of clay suspensions over the range 0.1 to 100 atm. The results obtained with this apparatus for a number of illite samples are consistent with those predicted by theory.

Consideration of the implications of these experiments for the mechanism of flocculation favors the following conclusions: (1) The attractive forces acting between clay particles in flocculated suspensions are probably a simple Coulombic attraction between negative and positive sites on the respective particles; (2) Van der Waal's forces are of no consequence in flocculation phenomena in the suspensions studied; (3) The energy of flocculation is small and cannot contribute significantly to the resistance of aggregates to mechanical breakdown.
Effect of Moisture and Phosphate Variables on Alfalfa Hay Production on the Yuma Mesa
Authors: Stanberry C. O. , Converse C. D. , Haise H. R. , Kelley O. J.
Published: July 2010

Alfalfa was grown on Superstition loamy fine sand on the Yuma Mesa for the 4‐year period, 1949–52, to evaluate the effects of moisture and phosphate variables on hay production and associated factors. The three moisture treatments were based on tension levels, tensiometers being installed at 9 depths from 6 to 120 inches. A total of about 125,000 tensiometer readings were recorded during the 4 years. Ten phosphate (superphosphate) rates and/or frequencies varying from 100 to 1,300 pounds P2O5 for the 4‐year period were employed as subplots in the split plot design.

Average annual hay yields for the 4‐year period varied from 6.4 to 12.3 tons per acre, being greatly affected by either moisture or P level. Small frequent irrigations and an initial fertilizer application of more than 200 pounds P2O5 plus 100 pounds P2O5 annually appeared to be the goals to approach. Phosphorus movement was largely limited to the surface 18 inches, which was less than expected. As measured by tensiometers the depth for the greatest relative activity of roots decreased with decreasing moisture tension, increased with decreasing supplemental phosphate, and increased with increasing temperatures.

Soil sampling during a 32‐month period revealed that for “dry”, “medium”, and “wet” treatments respectively, 80, 74, and 27% of the available moisture and 72, 82, and 85% of the total water utilized by the plant was removed from the surface 48 inches of soil. During a 3‐year period the mean water use per day varied from 0.21 to 0.25 inch, the greatest amount being used in the “wet” or low‐tension treatment. Water used per ton of hay produced varied from 7.1 to 16.5 inches, high rates of moisture and phosphate giving greatest efficiency.

The alfalfa stand thinned rapidly, correlation analysis indicating a reduced stand was an important cause for declining yields. Root grading analyses at the termination of the experiment demonstrated that moisture and phosphate levels had no effect upon root shape and nematode infection. Moisture and/or phosphorus had significant effects on crown and root weight, root diameter, amount and distribution of feeder roots, and crown‐ and root‐rot. A barley crop was grown following the alfalfa to measure residual productivity levels due to previous moisture and phosphate variables. The only significant difference was caused by moisture, the “dry” treatment resulting in the greatest grain yields.
A Chemical and Mineralogical Study of Clay Materials from Several Gray‐Brown Podzolic Soils of Minnesota
Authors: Caldwell A. C. , Farnham R. S. , Hammers F. L.
Published: July 2010

Soil samples were collected from two Fayette soils developed from Peorian loess, one Milaca formed from non‐calcareous glacial till of Cary substage of the Wisconsin, and one Hayden soil developed from calcareous glacial till of Mankato substage of the Wisconsin. Morphological observations placed these soils in the Gray‐Brown Podzolic group. Mechanical analysis showed these soils to be silt loams. Some accumulation of clay in the B2 horizon substantiated field observations of some podzolization having occurred.

The clay material less than 0.5µ in size was separated from the A1, A2, B1, B2, and C horizons of these profiles. Total chemical analysis of the clay fraction showed little differentiation in content of inorganic constituents within and between profiles. X‐ray diffraction and differential thermal analysis of some of the clays indicated clay minerals largely of the montmorillonitic type. Relatively high total exchange capacities of the clays were indicative also of montmorillonitic types of clay minerals.
Investigations on the Mobilization and Transport of Iron in Forested Soils. II. The Nature of the Reaction of Leaf Extracts and Leachates with Iron
Authors: Schnitzer M. , DeLong W. A.
Published: July 2010

Electrodialysis of poplar leaf extracts enriched with iron indicated that the major part of the iron was present either as ferric hydroxide or in a form readily convertible to the latter. Interaction of such solutions with iron produced only a general increase in light absorption: no absorption maxima indicative of chelation were observed. The major part of the iron present in these enriched aqueous solutions could be recovered by extraction with 8‐quinolinol in chloroform.

Fractions isolated from poplar leaf extracts and leachates by precipitation in 80% aqueous ethanol possessed the major part of the capacities of these solutions to react with iron. Evidence was obtained that the principal component of these active fractions had the characteristics of an acidic polysaccharide. Potentiometric titrations of these active fractions in presence and absence of ferric ions failed to reveal evidence of chelation.

It is concluded that both the forest canopy and the forest floor contribute solutions capable of the mobilization and transport of iron, and conclusions are drawn relative to the conditions favourable to such action of these solutions.
Some Site Factors Affecting the Success of Reforestation and Afforestation Activities in the Willamette Valley Foothills
Authors: Youngberg C. T.
Published: July 2010

The majority of the land in the low‐lying hills adjacent to the Willamette Valley is not suited for agriculture due to the nature of the soils and topography, and supports a cover of Douglas fir, mixed Douglas‐fir‐Oregon white oak, and oak stands. Scattered through the area are non‐forested openings supporting grass or grass and oak. The soils are clay loam or clay textured derived from basalt, shales, and sandstones with some alluvial fan soils on the lower foot slopes. Summer rainfall is negligible and humidities are generally low during the growing season.

This paper reports some preliminary findings of the studies of soil moisture relations and the physical factors affecting them on several areas where reforestation or afforestation has been attempted. Soil profile descriptions are given, and results of laboratory analysis including mechanical analysis, bulk density, range of available moisture, and nutrient status are also reported. Several seasonal soil moisture curves are presented. The results of the study suggest that the narrow range of readily available moisture, i.e., water held at low tensions, in many of the soils of this area is responsible for the difficulties encountered in the attempts at reforestation and afforestation.
Solubilization of Soil and Rock Phosphate as Related to Root Cation Exchange Capacity
Authors: Drake Mack , Steckel J. E.
Published: July 2010

Plants with root cation exchange capacities ranging from 10 to 60 me./100 g. dry root, were grown in greenhouse pots on B horizon Merrimac silt loam very low in available and total phosphorus. Rock phosphate at the rate of 1,000 pounds per acre was mixed throughout the soil. Plants with high cation exchange root systems (ragweed and smartweed) were more effective in obtaining phosphorus from soil and rock phosphate for themselves, and were two to three times as effective as the lower exchange root systems (Lamb's quarters and wheat) in solubilizing soil and rock phosphate for the following crop of sudan grass. Oats with relatively low cation exchange roots, when grown in association with red clover (high cation exchange roots) contained 60% more phosphorus than oats alone. Plant roots with high cation exchange capacity bond Ca with greater energy than low cation exchange roots. Two important mechanisms of P release are believed to be involved, (a) bonding of Ca by the plant root colloid to dissolve the rock phosphate crystal and (b) complexing of Al and Fe by organic anions to solubilize soil Al and Fe phosphates.
Application of Solubility Product Principles to the Variscite‐Kaolinite System
Authors: Kittrick J. A. , Jackson M. L.
Published: July 2010

The reaction of variscite with H+ and OH‐ in water solutions was investigated and the [OH‐] exponent in the variscite solubility product expression was found to be dependent upon solution pH, being proportional to [OH‐]2 only at pH 4. An increase from 1 to 10 g. of kaolinite to 0.5 g. of variscite in 50‐ml. volume increased the aluminum concentration in solution from 2.3 × 10‐5 to 4.8 × 10‐5 molar and diminished the phosphate concentration in solution from 2.5 × 10‐4 to 0.7 × 10‐4 molar in accord with solubility product principles.
Subirrigation and Plant Nutrition I. Alfalfa Root Distribution and Soil Properties
Authors: Fox R. L. , Lipps R. C.
Published: July 2010

Root systems of subirrigated alfalfa plants and some associated soil properties have been studied. Under certain conditions a concentration of fibrous roots occurred in saturated soil above and below the water table. Roots occurred in abundance in pockets of fine sand and silt while adjacent pockets of moist sand and gravel were essentially devoid of roots. These observations and soil analyses suggest that root distribution is, in part, governed by nutrient availability.

Nodules occurred in abundance in the A horizon of a buried soil while the surface soil, which was more acid, contained roots without nodules and with only limited branching. Alfalfa roots penetrated soil horizons which contained much sodium. They branched extensively in a region of high sodium where calcium and magnesium were present in abundance.

Root distribution of subirrigated alfalfa suggests two important regions of water and nutrient sorption. These are the moisture fringe above the water table and the surface soil. Both should be considered when interpreting soil tests, evaluating results of fertilizer experiments, and explaining plant growth variations.
A Comparison of Several Chemical Methods With the Bio‐assay Procedure for Extracting Zinc from Soils
Authors: Tucker T. C. , Kurtz L. T.
Published: July 2010

A study was made to evaluate the forms of soil zinc removed by the Aspergillus niger bio‐assay method and to compare several chemical procedures for extracting soil zinc. Soils used were from humid regions; only one was calcareous.

For 0.1N HCl, the effects of extraction time and ratio of soil to extracting solution were investigated. A ratio of 1:10 and a 45‐minute shaking period were considered most satisfactory. Longer extraction periods and wider ratios resulted in removal of larger amounts of zinc, but the rate of zinc release diminished appreciably. The amount of soil zinc removed by 0.1N HCl during a 6‐week extraction period, by successive extractions with 0.1N HCl, and the bio‐assay values were approximately equal. This agreement suggests the existence of an acid soluble form which made up around one‐fifth of the total soil zinc in the soils studied. Very little zinc was found in the exchangeable form, and the organic form, if present, was apparently small.

Amounts of zinc extracted with 0.1N HCl, acetic acid, EDTA, and dithizone were significantly correlated with the bio‐assay values. Dithizone and EDTA removed about the same amounts of zinc. The bio‐assay, dithizone, and 0.1N HCl procedures were most convenient and rapid. The acetic acid procedures appeared to be the least satisfactory since the range among soils was small at narrow soil to solution ratios, and extracts were too dilute for ready determination at wider ratios.

Zinc fertilization of the soil was reflected in zinc soil test values and plant content.
A Study of the Genesis of a Podzol—Gray‐Brown Podzolic Intergrade Soil Profile in Michigan
Authors: Cann D. B. , Whiteside E. P.
Published: July 2010

A modification of the resistant mineral method used by Marshall and Haseman was applied to a study of the genesis of a Podzol—Gray‐Brown Podzolic Intergrade soil profile in Michigan. Changes in the method were (1) the use of quartz, instead of zircon, as the reference mineral, (2) the determination of quartz with a Geiger counter X‐ray spectrometer, and (3) the use of the coarser fractions of the soil.

Results show that: (1) There is a total loss in weight of the solum, but a 20% gain in volume, which takes place largely in the A1, A2P and BP horizons; (2) About 85% of the soluble material originally present has been removed from the profile; (3) Orthoclase feldspars showed a slight gain in the profile, about equal to the net loss in weight. This indicates that they are very resistant to weathering. Plagioclase feldspars had decreased considerably in A2P and BP horizons but very little in B2GB horizons. (4) Marked increases in organic matter in the BP horizons and in organic matter and clay in the B2GB horizons seem to indicate that both of these are illuvial horizons. However, the principal constituent concentrated is organic matter in the Podzol B and silicate clay in the Gray‐Brown Podzolic B. It seems certain that the two illuvial processes are now occurring simultaneously in this soil.
The Influence of Soil Crusts on Gaseous Diffusion
Authors: Domby C. W. , Kohnke Helmut
Published: July 2010

A method is described for forming crusts on soils in special containers in the laboratory using artificial rainfall, and for measuring gaseous diffusion through these soils without further disturbance of their structure.

Unless the surface is completely impervious, the rate of diffusion through a soil does not depend solely on the properties of this layer. When various proportions of the soil surface were sealed with paraffin, the rate of diffusion was not reduced in proportion to the area covered.

The effects of soil crusts upon diffusion depended to a very great extent on the soil moisture tension. There were no significant differences in the rates of diffusion through air‐dry silt loam having different degrees of crusting. Surface crusts on this soil restricted diffusion only at low moisture tensions; the wetter the soil, the greater the influence of the crust on diffusion. Except in the very wet range, even minor variations in soil moisture tension had more influence on diffusion than did the presence of a thin surface crust.

A saturated soil crust could provide a very effective seal against diffusion at the time when soil aeration is most critical, i.e. during and for a short time after a rain or irrigation. Except during a period of complete sealing, however, crusted soils actually may permit more rapid diffusion and be better aerated than mulched or other uncrusted soils, because of differences in moisture content.
A Study of the Properties of Molybdenum in Everglades Peat
Authors: Fiskel John G. A. , Mourkides G. A. , Gammon Nathan
Published: July 2010

Analyses of samples of Everglades peat from the vicinity of Lake Apopka, Fla., showed a tenfold variation in total molybdenum between fields, while the water‐extractable molybdenum varied from 0.017 to 2.60 ppm. on the basis of the weight of oven‐dry peat. The water‐extractable fraction was found in appreciable quantity at all depths. Subsequent leaching with other extracting solutions used in sequence on the same samples, showed the following range of values expressed as ppm. Mo of the oven‐dry peat: one sequence 0.017 to 1.10 using borax in the rate of 50 pounds per acre in water, and 0.22 to 0.37 in the leachate following addition of superphosphate at the rate of a ton per acre; another sequence 0.03 to 0.07 ppm. removed by neutral N NH4Ac, followed by 0.044 to 0.120 ppm. removed in the leachate using 0.05% hydroquinone in 50% alcohol, and finally 2.5 to 10 ppm. with 1 N NH4OH. Several materials were added to the peat on pasture areas, the rates being 750 pounds per acre each for kaolin, vermiculite fines, ball clay, colloidal phosphate, bauxite and attapulgite; 500 pounds per acre of a Krilium‐9 formulation and of sulfur powder; 200 pounds per acre of Krilium‐931 formulation; and 150 pounds of a manganese source material (Nu‐M) and of a copper source material (Tribasic copper sulfate). Of these materials attapulgite, Krilium, and bauxite reduced the water‐extractable and ammonium hydroxide‐extractable molybdenum in the peat and also significantly reduced the molybdenum content of the herbage. Attapulgite and perhaps bauxite offered a longer lasting and less expensive measure of controlling molybdenum availability than the sulfur or the Krilium formulations.
Sulfur and Nitrogen Composition of Fertilized and Unfertilized Alfalfa Grown on a Sulfur‐Deficient Soil
Authors: Rendig V. V.
Published: July 2010

A study was made of the effects of three levels of S fertilization (0, 200, 400 lbs. gypsum per acre) on several forms of S and N present in alfalfa grown on Delhi sand in the San Joaquin Valley of California. Previous studies with alfalfa on this soil have shown that the annual yield could be approximately doubled by an application of 200 lbs. gypsum per acre and that phosphate fertilizer had no significant effects on yield or P content.

Yield data were obtained at each of five successive cuttings of alfalfa. Forage samples were analyzed for total N, amide‐N, free‐amino‐N, total S, SO4‐S, and methionine.

At all harvests, yields were increased by S; slightly higher yields were produced by 400 than by 200 lbs. gypsum per acre, the difference being significant for only the first two cuttings. For the first three harvests, the percentage of total S in the plant was approximately 3 times as great in alfalfa grown with 400 lbs. gypsum as in that grown without fertilization; the differences were progressively smaller at the fourth and fifth harvests. Most of the differences in S content could be accounted for as SO4‐S; however, a consistent difference in reduced‐S was also noted, with maximum variation occurring at the third harvest, when the reduced‐S contents were 0.11 and 0.17%, respectively, for alfalfa from plots receiving 0 and 400 lbs. gypsum per acre. This difference in reduced‐S could not be accounted for as methionine; actually the percentage of the reduced‐S present in this form was higher in the unfertilized alfalfa.

Marked differences in N content were found only at the first harvest, when crude protein values were 17 and 24%, respectively, for alfalfa grown with 0 and 400 lbs. gypsum per acre. Contents of amide‐N, free‐amino‐N, and NO3‐N were interpreted as indication that the lower crude protein content of the unfertilized alfalfa was not caused by lack of S in the plants.

The conclusions were drawn that (1) the alfalfa was not enriched in methionine by fertilization with S, and (2) the synthesis of some form of reduced‐S was impeded in the unfertilized alfalfa by lack of sufficient available S.
Molybdenum in Everglades Soils and Plants
Authors: Kretschmer Albert E. , Allen Robert J.
Published: July 2010

Everglades organic soils are underlain with limestone rock, and with continued cropping subsidence occurs and pH values rise. A rather high total Mo content in these soils encouraged work to determine the Mo accumulation by plants as affected by soil factors. A survey of Mo and Cu contents of forages grown throughout the area also was made to determine the Mo status of forages being grazed. As an index of forage not harmful to grazing cows, a Cu content of 10 ppm., or greater and a Mo content of 3 ppm. or less in the forage was chosen from previous animal tests.

It was found that increasing the pH of the soil resulted in Mo accumulations of greater than 25 ppm. by clover plants. Not only is there a great difference between Mo contents of various winter forages grown under the same conditions, but contents seem to vary as a result of plant maturity and season. Roselawn St. Augustinegrass and Bermudagrass growing in commercial pastures were found to absorb less Mo than other grasses tested, while pangolagrass and white clover absorbed larger amounts. Furthermore, trends seem to indicate that plants grown on a given soil will accumulate more Mo as the period of cropping increases, even though the soil pH remains constant.

Although the Mo contents of permanent pastures are not as high as those reported in other troubled areas, the Mo‐Cu status indicates the possibility of unfavorable forage quality during the fall. Average Mo and Cu contents of approximately 100 survey samples were found to be 5.5 and 7.4 ppm., respectively, in the fall, and 2.9 and 10.9 ppm. in the spring.