bluuebunny/crossref_metadata_2025 huggingface dataset:
Fertilizer Studies in the Cauca Valley of Colombia
Authors: Lawton K. , Patino E.
Published: July 2010

Nine field fertilizer experiments involving six major crops were conducted over an 18‐month period in the Cauca Valley of Colombia. The area of moderate fertility selected for study was a farm located on a slightly sloping outwash adjacent to the Andes mountains. In addition to different crops, other variables under investigation included kind and rate of application of fertilizers, plant population, and irrigation.

With two similar experiments on corn conducted at the same time on different soil areas, marked yield response to phosphorus fertilizer was obtained at one location, whereas at the second, neither nitrogen nor phosphorus were beneficial. A third experiment dealing with fertilizer, irrigation, and plant population showed that supplemental water and adjustment of stand were more important than fertilizer requirements in determining corn yields.

Yields of field beans in one trial were significantly increased by use of nitrogen fertilizer, but only small benefits were obtained from phosphorus. For soybeans, direct application of fertilizer was only of moderate value in improving yields of grain.

With sugar cane, one experiment indicated both phosphorus and potassium were needed for high cane production. Nitrogen fertilizer applied to newly planted Pangolagrass was highly effective in increasing forage yield, while response to phosphorus was negligible.
Characteristics of the Multiple Yellowish‐Red Bands Common to Certain Soils in the Southeastern United States
Authors: Robinson Glenn H. , Rich C. I.
Published: July 2010

Multiple bands or strata of soil materials, which are finer textured and browner or redder colored than the material above or below, have been studied. These bands are common in unconsolidated sandy Coastal Plain and glacial deposits. In Virginia, North Carolina, and South Carolina they are found to lie nearly horizontally, are much deeper where the present soil is nearly level than on sloping soil areas, and the soils in which they occur contain “clay balls” and band segments above the continuous bands. Stratification within the bands, charcoal fragments deposited with the sand, and bands showing scour and fill characteristics were observed in the field. In no instance were yellowish‐red bands found to cross bedding planes but rather the redder color follows the texture of the strata.

Chemical analyses show that these bands, where continuous, contain more organic matter, and have a slightly lower pH and higher cation‐exchange capacity than the interbands. Percentage free iron in the clay fraction, and clay mineral analyses show no significant differences between the bands and interbands.

Attempts to develop clay‐iron oxide strata in the laboratory by leaching unstratified soil materials were unsuccessful. However, some were developed in stratified materials when leached with a complexing or reducing agent. These experiments produced evidence that clay movement in a sandy medium is similar under some conditions to clay movement in a finer textured medium and give support to the conclusion that the bands studied are primarily the result of geologic deposition.

Based upon this conclusion, it is proposed that the part of the profile containing such bands be considered as the C horizon of the soil above. The small residual “clay balls” or segments of bands remaining in the B horizon (often a color B) would be considered as fragments of parent material and comparable to partially weathered rock fragments in the lower B of a residual soil.
Non‐Steady‐State Moisture, Temperature, and Soil Air Pressure Approximation With an Electric Simulator
Authors: Hanks R. J. , Bowers S. A.
Published: July 2010

An electric simulator was used to approximate the non‐steady‐state, one‐dimensional solution of several moisture, temperature, and air pressure problems in soil. The simulator consists of a resistance‐capacitance network with accessory units for setting initial conditions and recording or indicating the simulated variable with time and depth. Time and distance can be scaled to convenient magnitudes. Provision for changing the simulated diffusivity with distance and time allows for the approximate solution of several types of moisture problems. An example of absorption, redistribution after absorption, and evaporation from Yolo light clay is given. The absorption solution compares favorably with the mathematical solutions of Klute and Philip.

Comparison of mathematical and simulated solution of temperature distribution in a soil with constant diffusivity and temperature varying sinusoidally at the surface shows excellent agreement. The soil temperature (fluctuating with time) between two measured depths is estimated. The solution agrees reasonably with actual field measurements. The solution of the problem of air pressure fluctuation within the soil due to fluctuation at the surface is given where an impermeable layer exists at a specified depth.
Physical and Chemical Properties of Some Peats Used as Soil Amendments
Authors: Dyal R. S.
Published: July 2010

More than half a million tons of peat are sold annually in the United States for soil improvement. The properties of interest to the buyer and seller are discussed and data for these properties given. Dry organic matter of peats as sold are reported as follows: bulk 26.6, bale 66.4, and moisture‐proof packages 37.7 pounds per 100 pounds of peat. The pressure‐plate and pressure‐membrane procedures, as used in soils work, are shown to be satisfactory for measuring moisture‐retention properties of peats.
Utilizing Drought‐Days in Evaluating Irrigation and Fertility Response Studies
Authors: Parks W. L. , Knetsch J. L.
Published: July 2010

It is expected that a crop grown during a year of insufficient moisture will economically require less fertilizer than a similar crop grown with an ample supply of moisture. Likewise, crop response to supplemental irrigation would be greater during a year of low rainfall than during a year of adequate rainfall.

The moisture deficiencies may be expressed as “drought‐days” for any specific soil‐crop‐fertility situation. Incorporating “drought‐days” as a production function to characterize the factor‐product relationship as shown in the general equation below permits an evaluation of the effects of drought on yield and on the interactions with other variables such as fertility.

Y = b0 + b1N + b2N2 + b3D + b4D2 + b5ND. Where Y = yield, N = pounds of nitrogen per acre and D = drought‐days or drought index.

A history of drought conditions for an area may then be used to obtain probabilities of the frequency of occurrence of varying degrees of drought and consequently the effect on yield outcome. This permits the presentation of yield outcome in terms of risks for various inputs rather than as single valued outcomes.

Irrigation may be expected to reduce the number of drought‐days encountered in any cropping situation. Expressing crop yields as a function of drought‐days and fertility level permits the evaluation of irrigation on yield and subsequent crop income. Combining this with the probabilities for drought occurrence provides a means for determining the expected irrigation response in an area and attaching probability statements relative to such a response.
The Effect of Exchangeable Calcium on the Retention of Phosphorus by Clay Fractions of Soils of the Memphis Catena
Authors: Calvert D. V. , Massey H. F. , Seay W. A.
Published: July 2010

The effect of Ca saturation on P‐retaining properties of clay fractions of five Kentucky soils of the Memphis catena was studied. Changes in P retention and pH which occurred during storage of acid‐washed clays were investigated. Retained P was considered to be that portion of added P removed by the clay separate from a water solution.

A definite change occurred in the P‐retaining properties of initially acid‐washed clay separates during storage as evidenced by the decrease in P and P32 remaining in solution and the increase in pH. This change was attributed to an increase in A1 saturation of the exchange complex.

With freshly acid‐washed clay separates of all soils of the catena, P retention generally increased with increased Ca saturation, whereas P retention for clays aged after acid‐washing generally decreased as Ca saturation increased.

It is suggested that in considering H, Ca and Al as exchangeable cations, P in solution decreases in the order given. Retention of added P by Memphis soil was about equal to the retention of added P by an aged Memphis clay separate.
Effect of Soil Type on Mobility of Zinc in the Soil and on Its Availability from Zinc Sulfate to Tung
Authors: Barrows Harold L. , Neff Marshall S. , Gammon Nathan
Published: July 2010

A field experiment was designed for study of the effects of soil type on movement of zinc in the soil and of soil type and levels and placements of zinc sulfate on growth of 1‐year‐old tung trees. The soils were Savannah and Red Bay fine sandy loams, Lakeland fine sand, and Arredondo loamy fine sand. The treatments consisted of the factorial combination of three levels of zinc sulfate with three placements and a check plot (no zinc sulfate).

At the end of 1 year the rate of zinc movement through the four soils was in the order Lakeland > Red Bay > Savannah > Arredondo. Very little zinc was absorbed by the tung trees from surface applications on the Arredondo soil, but the trees obtained sufficient zinc when the zinc sulfate was mixed with the soil. In contrast, zinc mobility on the Lakeland soil was so great that 1 ounce applied on the surface proved toxic.

Although there was little lateral movement of zinc in the soils, the movement was primarily toward the tree rather than away from it.
Influence of Temperature and Moisture on Soil Phosphorus I. Effect on Soil Phosphorus Fractions
Authors: Mack Alex R. , Barber Stanley A.
Published: July 2010

Soil incubated at −20.5° C. for 9 months released more phosphorus when leached with water than soil incubated at 2.7° C. At a leaching temperature of 32° C. more phosphorus was released than at 16° C. The amount of phosphorus released was correlated with a decrease in acid‐soluble phosphorus and an increase in alkali‐soluble phosphorus (iron phosphate) in the soil after leaching. It is suggested that preconditioning temperature changes either the types of phosphorus compounds or the surface area of those present in the soil. Incubating under anaerobic conditions increased the alkali‐soluble phosphorus; however, this phosphorus did not contribute to the supply of phosphorus available to the plant.
Availability of Sulfur to Rice Plants in Submerged and Upland Soil
Authors: Nearpass D. C. , Clark Francis E.
Published: July 2010

A deficiency disease of rice occurred on plants grown in Evesboro soil in pot culture, following submergence as customarily employed for lowland rice culture. This was apparently sulfur deficiency, since rice plants responded to various forms of sulfate sulfur in further pot tests.

In comparison experiments, sulfur uptake by rice plants was reduced by submerging the soil. In one experiment testing 5 levels of available sulfur in Evesboro soil, parabolic and logarithmic equations were solved for the relationship between plant uptake of sulfur and available sulfur in the soil. When both types of equations were solved for the best fitting values of soil sulfur, the values obtained in submerged and upland soil were comparable, indicating that both soil and fertilizer sulfur were subject to the same changes upon flooding.

In comparisons of submerged and upland conditions on five other soils, sulfur uptake was lowered by flooding the soil, regardless of the type of yield response, whether negative or positive, obtained from flooding. Sulfur percentage in the plants grown in flooded cultures was related to the yield response obtained from flooding. The soils which gave negative yield responses produced the lowest sulfur contents.

In further experiments, organic matter, in the form of dried and ground rice plant tissue, when added to flooded cultures, depressed the growth of rice plants. Sulfate, added along with the organic matter, overcame to various degrees the depression in growth. Prior submergence also had an ameliorating effect on the growth depression which occurred with flooding and organic matter.
Adsorption and Release of Strontium from Clays and Soils With Equilibration, Isotopic Tracer and Plant Uptake Techniques
Authors: McLean E. O. , Arscott T. G. , Volk V. V.
Published: July 2010

The percentages of Sr90 adsorbed by bentonite and illite clays when saturated to various degrees with the complementary ions H, Ca, Ba, and K were determined. The percentages of Sr90 taken up in an 8‐hour period by soybean plants from the above systems as well as from solutions containing the same total concentrations of the cations as the clays were also computed. The amounts of Sr absorbed by a soil containing various levels of exchangeable Ca (established by prior rates of liming in the field) were measured by equilibration with SrCl2 solutions. Sr was generally adsorbed less and taken up by plants more from illite than from bentonite. Addition of Ca or Ba as compared to H decreased Sr adsorbed and increased Sr uptake by plants from the clays, thus having the effect of accelerating the decontamination of the clays by cropping. Sr appeared to be bonded by bentonite but not by illite with sufficient energy to restrict its uptake by soybeans. Increased level of exchangeable Ca in a soil did not appreciably affect the amounts of Sr adsorbed from SrCl2 solutions.
Sequential Products of Anaerobic Denitrification in Norfolk Soil Material
Authors: Cady F. B. , Bartholomew W. V.
Published: July 2010

Soil samples containing tagged nitrate were incubated in a compact, small volume, glass apparatus constructed to provide internal circulation of the gaseous phase. Periodically, samples of the circulating gas were taken and analyzed directly on the mass spectrometer.

The initial gaseous denitrification product to appear was nitric oxide (NO). However, the amount of NO to appear in the gaseous phase never exceeded 5% of the tagged nitrate added to the soil. The presence of NO in the gaseous phase was closely associated with the presence of nitrite in the soil and is presumed to have arisen from the decomposition of nitrous acid.

Subsequent to the appearance of nitric oxide, nitrous oxide (N2O) appeared in the gaseous phase. Coincident with the increase in N2O was a decrease and eventual disappearance of NO. Following the increase in N2O was the appearance of nitrogen gas (N2). This increased in amount sufficient to account for 83 to 95% of the added tagged nitrate coincident with the reduction in amount and eventual disappearance of N2O.
Influence of Temperature and Moisture on Soil Phosphorus: II. Effect Prior to and During Cropping on Soil Phosphorus Availability for Millet
Authors: Mack Alex R. , Barber Stanley A.
Published: July 2010

Millet was grown with and without added phosphorus at one temperature and moisture level on samples of two soils which had been incubated for 74 days at 23°, 2.7°, and −20.5° C. and at moistures of 40, 60 to 70 and 100 percent of field capacity. The higher the soil temperature prior to cropping, the greater was the yield of dry matter and phosphorus uptake. Soil moisture contents prior to cropping did not affect yield and phosphorus uptake. Millet was also grown at three soil moisture levels and at two soil temperatures. The effect depended on the accompanying temperature. The soil moisture level did not affect the yield and phosphorus uptake at a soil temperature of 16° C. but did affect it at a soil temperature of 21° to 33° C. during the cropping period. Response to phosphate in field trials with wheat was related to both temperature and rainfall during the growing season.
Efficiency of Recovery of Applied Nitrate Nitrogen by Perennial Ryegrass from Different Soils
Authors: Grable Albert R. , Johnson Donal D.
Published: July 2010

The objectives of this study were to determine efficiency of recovery of applied nitrate nitrogen on 7 pairs of soils fertilized at 4 rates of nitrogen and to relate these results to intrinsic soil properties. Soils were sampled so that texture and organic matter content were the main soil variables. Ryegrass was grown on the soils until added nitrogen was exhausted.

Nitrogen fertilizer was generally more efficient at the higher rates of application, but not on all soils. Efficiency decreased with rate on a few soils and remained constant on others. Two of the soil pairs showed significantly lower nitrogen efficiency than the other five. Low efficiency on one soil appeared to be caused by relatively lower dry matter production for each unit of applied nitrogen. Efficiency was much higher in this experiment than on the same soils in situ.

Regression analyses indicated that efficiency was not related to ability of the unfertilized soils to yield nitrogen; i.e., increases in yield of nitrogen due to nitrogen applications controlled efficiency rather than the absolute yield of nitrogen. Some 53 and 70% of the variation in average nitrogen efficiency for the 14 soils was associated with percent clay and surface area, respectively. Because efficiency was lower on finer‐textured soils, it was proposed that lower efficiency may have been caused by denitrification losses brought about by slower oxygen diffusion.
An Evaluation of Tillage Practices for Winter Wheat in the Semiarid Region of Southwestern Kansas
Authors: Brady Homer A.
Published: July 2010

Three methods of seedbed preparation for winter wheat (stubble‐mulch tillage, one‐way disking, and moldboard plowing) were evaluated for the semiarid region of southwestern Kansas. Although fallow is recommended for the area, both continuous cropping and wheat‐fallow sequences were used in the comparison. Measurements of grain yield, soil moisture, evaporation from soil, soil temperature, soil nitrate, and notes concerning runoff and erosion by wind and water were included.

Subsurface tillage effectively controlled erosion by wind and water. Differences in the other factors tested were not statistically significant. On fallowed land slightly higher average yields were produced by one‐waying than subsurface tillage or plowing. Subsurface tillage gave the highest yields on continuous cropping. Visual observations indicated that runoff was less from subsurface tillage plots but higher evaporation under the residue mulch left moisture levels nearly equal. Soil temperature averaged slightly higher under a stubble mulch; the soil warmed more slowly in the spring and cooled more slowly in the fall. Nitrate levels were highest on plowed, somewhat lower on one‐wayed, and least on subtilled plots. Free nitrate levels were considered an indication of the rate of decomposition of organic matter.
Corn Growth on Gardena Surface and Subsoil as Affected by Applications of Fertilizer and Manure
Authors: Carlson C. W. , Grunes D. L. , Alessi J. , Reichman G. A.
Published: July 2010

A study was conducted in the field to evaluate the fertility requirements of a Gardena fine sandy loam subsoil as compared to an undisturbed soil. Corn was grown on both areas the first and third years after land leveling.

Where the topsoil had been removed, the most deficient element was N, followed by P and then Zn. Zn increased corn grain yields both the year it was applied, and 2 years later. Manure applied the first year after leveling increased corn yields that year, and supplied residual P and Zn 2 years later. However, the yields on manured plots were not as high as those obtained with applications of N, P and Zn.

Applications of N and P increased yields slightly on the undisturbed area. It was necessary to apply N, P, Zn and manure to make yields on the subsoil equal those on the surface soil.
The Germination of Corn and Wheat as Affected by Various Fertilizer Salts at Different Soil Temperatures
Authors: Cummins D. G. , Parks W. L.
Published: July 2010

Corn and wheat were germinated at different concentrations of various fertilizers in growth chambers. Three temperature levels were maintained in the controlled tests. The fertilizers ranked in the following order with decreasing detrimental effects on the germination of corn: anhydrous ammonia, urea, nitrate of soda, muriate of potash, ammonium nitrate, ammonium sulfate, 6‐12‐12 fertilizer, sulfate of potash, 48% superphosphate, and 20% superphosphate. The fertilizers ranked in the following order with decreasing detrimental effects on the germination of wheat: anhydrous ammonia, urea, muriate of potash, nitrate of soda, ammonium nitrate, ammonium sulfate, sulfate of potash, 6‐12‐12 fertilizer, 48% superphosphate, and 20% superphosphate. Corn was tolerant to a higher salt concentration than was wheat. The nitrogen and potash fertilizers were more detrimental to germination than were the phosphate fertilizers. The temperatures studied had no significant effect on the tolerance of corn and wheat to salt concentration. Corn did not germinate at 50° F.
Yield Response in Experiments With Phosphorus Fertilizers in Relation to: II. Variability and Differences Among Sources on Soils of Northern and Western States
Authors: Terman G. L.
Published: July 2010

Yield results from 124 experiments in Colorado, Iowa, New York, and Washington comparing phosphorus rates and sources, each including a response curve with CSP, were summarized in regard to the nature of the response and experimental error. In less than 10% of the tests with corn, small grain, and vegetables showing response to P was it possible to measure differences among sources from one‐half to twice as effective as CSP. Although experimental error was important, low response to applied P was the chief factor limiting the measurement of differences among sources. Coefficient of variation (CV) decreased with increase in mean yield of corn experiments in Iowa. Numerical increases in yields resulting from applied P were about the same at all yield levels in these experiments.
Irrigation Based on Soil Suction Measurements
Authors: Richards S. J. , Marsh A. W.
Published: July 2010

Soil suction (soil moisture tension) from zero to 0.8 bar is explicitly indicated by tensiometers. Higher values can be measured by suitably calibrated soil moisture resistance units. An irrigation program, both as to timing and duration of applications, can be carried out based on day‐to‐day records of soil suction at two or more depths in the root zone of the crop involved.

Available moisture depletion is a commonly used basis for recommending irrigation practices. Curves are presented which show that, when irrigation timing is based on a given value of available moisture depletion, irrigations may be applied at widely differing values of soil suction if soil texture varies. A layered soil experiment shows the usefulness of soil suction measurements for evaluating relative moisture conditions in soils of varying texture.

Examples are given of irrigation practices by avocado growers which are based on tensiometer readings. When related to soil suction measurements, an irrigation program is adapted to soil, climate, and plant variables.
Competition between Bacterial Strains Effecting Nodulation in Soybeans
Authors: Means Ura Mae , Johnson Herbert W. , Erdman Lewis W.
Published: July 2010

Competition between genotypes of Rhizobium japonicum was studied by using chlorosis‐inducing strains 76 and 94 to facilitate identification of strains recovered from the nodules of soybean plants. Chlorosis‐inducing strains were individually mixed in varying proportions with each of nine normal strains and the mixtures were used as inoculants on the Hawkeye and Lee varieties. The plants were cultured in the greenhouse under conditions previously described.

Technique studies indicated that with rare exceptions a single nodule contained only one bacterial strain and that chlorosis of sorghum seedlings produced by a water extract of a nodule was a reliable indication that the nodule contained a chlorosis‐inducing strain.

Strain 76 had a pronounced competitive advantage over all normal strains regardless of the proportions of the strain in the mixtures. As little as 1.1% of strain 76 in the mixture with strain 38 caused 85% of the nodules. Strains 31 and 71 were more competitive against strain 76 than were the other normal strains. Chlorosis‐inducing strain 94 was much less competitive against 8 of the 9 normal strains than was strain 76.

The extent of chlorosis of the soybean plants gave a rough estimate of the competitive relationships between strains. The varieties Hawkeye and Lee were essentially identical in response to the various mixtures.
Sr90 Uptake by Plants as Influenced by Soil Types and Liming
Authors: Haghiri F. , Sayre J. D.
Published: July 2010

A greenhouse study was conducted to determine the influence of various soil types and liming on the uptake of Sr90 by plants. There were highly significant differences in the total uptake and concentration of Sr90 by corn, soybeans, buckwheat, Sudangrass, and alfalfa from different soil types and liming. In general, the total uptake of Sr90 from acid Ashtabula, Miami, and Canfield soils was considerably higher than the total uptake from slightly acid Brookston soil. Liming depressed the total uptake of Sr90 by the plants grown on the acid Ashtabula, Miami, and Canfield soils; but had no effect on the total Sr90 uptake by the plants from Brookston soil. These differences appear to be associated partly with the differences in exchangeable calcium and pH of the soils. The accumulation of radiostrontium by the various plant species after 5 weeks of growth was in the order: Buckwheat > soybeans > alfalfa > Sudangrass = corn.
Lysimetric Measurements of Evapotranspiration Rates in the Eastern United States
Authors: van Bavel C. H. M.
Published: July 2010

A review is presented of various methods to determine the evapotranspiration rate under field conditions. It is shown that, at the present time, the data which have been collected by a suitable lysimetric method are the only ones that exist in quantity and that, at the same time, can be considered as reliable.

The conditions which must be met by a lysimeter installation for the accurate and representative measurement of the evapotranspiration rate are reviewed. It is shown that both the exposure as well as the moisture conditions in the soil of the lysimeter must be representative of those in the surrounding area if realistic values are to be obtained.

Selected data from four locations in the Eastern United States are presented and compared. It is shown that data for grass cover under a variety of geographic and climatological conditions do not vary greatly from one another. Such dependable comparisons as are available between different crops show that the differences between corn, wheat, and meadow crops are small though not insignificant. The need for additional and adequate lysimetric measurements of evapotranspiration rates in the eastern half of the United States is discussed as well as the necessity for making pertinent meteorological measurements to aid in the generalization of the data.
Soil Moisture: Technique of Control and Relation to Tomato Growth for Different Soils
Authors: Cannell Glen A. , Bingham F. T.
Published: July 2010

A method is given for soil moisture control in greenhouse pot studies using tomato plants. Tensiometers and cylindrical electrode type gypsum blocks were used for timing of irrigation. Through use of calibration curves which related volume of water loss to suction under plant growth the quantity of water to be added at each irrigation was also determined from instrument readings.

Dry weight yields (plants grown to fruiting stage) increased with decreasing soil suction and with increasing fertilizer levels.

By use of ratios of unit dry matter produced to unit water used, it was shown statistically that plant growth was affected by soil suction. The ratios were increased with increasing soil suction and with increasing fertilizer levels.
Soil Phosphorus Fractionation Studies
Authors: Patel J. M. , Mehta B. V.
Published: July 2010

Total soil phosphorus in 21 soils was fractionated into 5 components viz. (a) calcium phosphate, (b) adsorbed phosphate, (c) iron and aluminum phosphate, (d) organic phosphorus and (e) phosphorus which is insoluble in the reagents which dissolve (a), (b), (c) and (d) fractions. It is found that none of these forms of soil phosphorus is a definite fraction of total phosphorus. The amount of adsorbed phosphate gives the highest correlation (r = + 0.8341 significant at 1% level) with the uptake of phosphorous by sorghum plants. Also the amount of adsorbed phosphate gives a highly significant correlation (+0.9330 significant at 1% level) with available phosphate determined by 0.5M NaHCO3. There is also a correlation between the uptake of phosphate by sorghum plants and the amount of calcium phosphate, but the level of significance is much lower. There is no significant correlation between the plant uptake of phosphate and the amount of phosphorus in any one of the three remaining fractions, namely iron and aluminum phosphates, insoluble phosphate and organic phosphorus.
The Effects of Fumigants on Nitrate Production in Soil
Authors: Koike H.
Published: July 2010

Laboratory experiments were conducted to determine the effects of eight fumigants on the nitrification of (NH4)2SO4 and NH4OH (aqua ammonia) in 200‐g. samples of sugar cane field soils. All samples were incubated unamended and amended with 500 parts nitrogen as (NH4)2‐SO4 or NH4OH per million parts soil. Unamended and nitrogen‐amended soils were treated with the different fumigants. The soil samples were maintained at 50% moisture‐holding capacity and, at intervals, extracted for ammonium and nitrate nitrogen with 2 parts of a 0.3 N solution of K2SO4 to 1 part of soil. Ammonium nitrogen was determined by nesslerization and nitrate nitrogen by the phenoldisulphonic acid method; in both cases the Klett Summerson photoelectric colorimeter was used for comparisons.

Results indicate that, under the conditions of the experiments, DD at 40 gallons per acre, Telone at 40 gallons per acre, Dowfume W‐85 at 8 gallons EDB per acre, S‐1283 at 8 gallons per acre, and Vapam at 50 gallons per acre markedly inhibited nitrification for 4 to 8 weeks. The rate of nitrification increased appreciably shortly thereafter and decreased again as the supply of added ammoniacal nitrogen was depleted.

Allyl alcohol at 20 gallons per acre, Nemagon or DBCP at 3 gallons per acre, and PRD G‐10 at 40 pounds active per acre were less toxic to the nitrifying bacteria.

An aromatic oil used as a diluent for some of the fumigants did not cause a significant reduction in the rate of nitrification in soil.

Lysimeter studies with DD substantiated results obtained with the fumigant in other experiments. For a period of 8 weeks, very little nitrate nitrogen was leached through soils supplemented with NH4OH and fumigated with DD at the rate of 40 gallons per acre. In the soils which were not fumigated with DD, after the very slow initial rate during the first 2 weeks, nitrification proceeded uninhibited.
Iron Adsorption by Montmorillonite Systems: I. Preliminary Studies
Authors: Whittig L. D. , Page A. L.
Published: July 2010

In the study of Fe(III) adsorption by montmorillonite systems, a number of factors which could influence the amount of Fe adsorbed were investigated. Influencing factors considered were (a) extent of anion adsorption, (b) decomposition of montmorillonite by treatment with acid‐Fe(III) solutions, and (c) H+ ion concentration of the Fe(III) solutions added.

Samples of H‐montmorillonite (Wyoming Clay Spur bentonite, < 1µ diameter) were equilibrated with 0.1N solutions of Fe2(SO4)3, FeCl3, and Fe (NO3)3. Essentially the same amount of Fe(III) was adsorbed from each of the solutions used. In all cases, the amount of associated anion adsorbed was negligible. It is concluded that Fe(III) is not adsorbed as a complex ion containing sulfate, nitrate, or chloride under the conditions of this study.

H‐montmorillonite was washed repeatedly with 0.1N Fe2 (SO4)3, 0.1N FeCl3, and 0.1N Fe(NO3)3. Each washing was analyzed for Si and Al. The results show a small but measurable amount of decomposition of montmorillonite.

The amount of Fe adsorbed by H‐montmorillonite from 0.1N Fe(NO3)3 solutions containing increasing concentrations of HNO3 shows that Fe adsorption is affected by the H+ ion concentration of the solution used.
Effects of Aluminum on Sunflower Growth and Uptake of Boron and Calcium from Nutrient Solution
Authors: Hortenstine Charles C. , Fiskell J. G. A.
Published: July 2010

The effects of aluminum in solution cultures on growth of sunflower plants and uptake of boron and calcium were determined under greenhouse conditions. Measurements were made of plant height and weights of roots and tops. Total amounts of aluminum, boron, and calcium in the roots and tops were determined.

Aluminum in concentrations above 4 ppm. drastically reduced heights of plants and weights of tops and roots. Increases in concentration of aluminum had no effect on amount of boron in tops or roots. There were no significant effects from aluminum on amount of calcium found in tops. However, the amount of calcium in roots decreased as concentration of aluminum in solutions increased. Aluminum accumulated in large amounts in roots of sunflower plants, but there was no increase in the aluminum contents of tops as aluminum concentration in the solutions increased.
Diffusion of Ions in Bentonite and Vermiculite
Authors: Lai T. M. , Mortland M. M.
Published: July 2010

The diffusion of five ions into three different homoionic bentonite gels obeyed Fick's law with the special boundary conditions for diffusion into solids. The diffusion coefficients of the ions followed the sequence SO4 > Na > Rb > Ca > Cs for all three homoionic bentonite gels. The effect of exchangeable cation on the diffusion coefficient of the diffusing ion in bentonite gels followed the sequence K > Na > Li. The effect of exchangeable cation on the activation energy and distance between successive absorption sites of the diffusing cation followed the sequence Li > Na > K. Cs ion diffused into Csvermiculite but not into Na‐vermiculite. SO4= ion mobility was higher at low clay concentrations than in pure water. As clay concentration increased, SO4= ion diffusion rate decreased more rapidly than that of exchangeable Na+ ion. The factors affecting diffusion of ions in clay gels are discussed.
Morphology and Classification of Certain Soils in East‐Central Minnesota and Northwestern Wisconsin
Authors: Erickson R. A. , Paschall A. H.
Published: July 2010

This is a report on investigations made of soils on the northern and eastern periphery of the Grantsburg sublobe of the Des Moines lobe (Mankato) located in east‐central Minnesota and northwestern Wisconsin. Sola of these soils are developed in Cary and post‐Cary parent materials, ranging from sandy loam to silt loam in texture. Most of the profiles are developed in silts of varying thickness overlying tills of the Cary ground moraine. Modal profile descriptions are summarized. Selected physical and chemical characteristics are presented.
Correlations between Constituents in Irrigation Waters and Irrigated Soils in Kansas
Authors: Jacobs H. S. , Naddih B. I. , Dixon R. M.
Published: July 2010

Soil and water from 26 sites from north‐central and southwestern Kansas were studied to determine if knowledge of the chemical composition of irrigation water could be used to predict salt and Na accumulation in soil. Samples were collected in the summer of 1958 and 1959.

Mean exchangeable Na percentage in irrigated soils can be predicted with reasonable accuracy from constituents in irrigation water using Gapon's equation, soluble Na percentage, or the Na adsorption ratio as the basis for estimation. Exchangeable Na percentage can be estimated with an accuracy of ± 1.8 at the 0.90 probability level for 25 out of the 26 soils.

Correlation between conductivity of soil saturation extracts and that of irrigation water was 0.98 when observations were restricted to soils that (a) increased in total salt content upon irrigation and (b) in which conductivity of the saturation extract exceeded that of irrigation water. Maximum irrigation water electrical conductivity used on such soils was 2.28 mmho per cm. For this value, soil saturation extract electrical conductivity could be predicted with an accuracy of ± 0.54 mmhos per cm. at the 0.90 probability level.

Electrical conductivity of soil saturation extracts varied from 0.4 to 4.7 mmho per cm. at 25° C. Mean exchangeable Na percentage ranged from 0.1 to 6.2. Irrigation water ranged in conductivity from 0.3 to 4.9 mmho per cm. at 25° C.
The Effect of Atomic Weight of the Saturating Ion on the (001) X‐Ray Diffraction Peaks of Layer Silicates
Authors: Kittrick J. A.
Published: July 2010

It was found that Tl+ saturation strongly diminished the intensity of the diagnostic (001) peaks of glycerated montmorillonite and vermiculite. Further experiments showed that the (001) X‐ray diffraction peak of expanding layer silicates decreases with increase in the amount of X‐ray scattering material contributed by the ions saturating the exchange sites. Intensity calculations indicate the mechanism to be ordinary destructive interference of diffracted X‐rays and that Tl+ contracts vermiculite to the mica structure.
Hydraulic Gradients Associated with Infiltration in Field Studies
Authors: Cannell Glen H. , Stolzy L. H.
Published: July 2010

A field method is described for measuring hydraulic head changes with time during infiltration of water into the soil. Using graphical methods, the hydraulic head and hydraulic gradient relationships for depth with time were established. From the sets of curves developed, soil depths were determined where soil physical properties influenced water flow during infiltration.
Miscible Displacement: II. Behavior of Tracers
Authors: Biggar J. W. , Nielsen D. R.
Published: July 2010

It is of interest to know the microscopic flow velocity distribution of water moving through soil. Dissolved constituents frequently have been used to trace water movement in porous materials. It is apparent from this and previous investigations, that the distribution of a tracer some distance from its source, depends upon the geometry of the porous material and the physical and chemical interaction of the tracer solution and media during flow. Therefore, investigators studying water movement using tracers are compelled to ascertain the importance of the interaction of tracer solution in the media. Tritium and chloride ion were used as tracers for water flowing under stationary conditions in laboratory soil columns. The distribution of the tracers measured in the effluent is explained on the basis of the relative effects of pore geometry, diffusion rates, adsorption and exchange.
Gamma Scintillation Spectrometry of Soil and Tree Leaves
Authors: Mortensen J. L.
Published: July 2010

A two‐crystal spectrometer was developed for gamma scintillation spectrometry of low‐level environmental samples. Response to gamma‐rays and resolution, efficiency, and background characteristics of the spectrometer were determined.

Spectra of gamma emitters in Canfield silt loam sampled in August, 1960, showed the presence of thorium + daughters, uranium + daughters, K40, Cs137 (190 mc. per mile2), Ru106‐Rh106 (885 mc. per mile2) and Ce144‐Pr144 (1275 mc. per mile2). Spectra of tree leaves obtained in the fall of 1959 and counted in June, 1960 showed the presence of Ba140‐La140, K40, Ru106‐Rh106, Zr95‐Nb95, Cs137, Ce144‐Pr144. Leaves sampled in the fall of 1960 contained K40, Cs137, Ru106‐Rh106 and Ce144‐Pr144.
The Aeration‐Recovery Method for Determining Ammonium Fixation by Soils Under Moist Conditions
Authors: Leggett G. E. , Moodie C. D.
Published: July 2010

A method for determining NH4 fixation by soils under moist conditions is described. Alkaline aeration in the presence of K is used to remove the soluble and exchangeable NH4 from NH4‐treated soil. The liberated NH3 is collected in standard acid and determined by titrating with standard NaOH. The NH4 fixed by the soil is obtained from the difference between NH4 added and that recovered.

Comparative data presented for several soils indicate that NH4 fixation values obtained by the proposed method agree with those obtained by determining the difference in N content of NH4‐treated and untreated samples after extracting with KCl solution to remove the soluble and exchangeable NH4.

Data are presented which indicate that NH4 fixation by soils may be measured with a precision of ±0.1 me. per 100 g. by the proposed method.
The Absorption of Nutrient Elements by Tomatoes Associated with Levels of Bulk Density
Authors: Flocker W. J. , Nielsen D. R.
Published: July 2010

Data are presented to show some of the relationships between soil moisture tension, air space, and soil density and their effect on the total nutrient absorption by tomato plants. Every effort was made to establish clearly defined treatments and evaluate changes in soil moisture during the experiment. The experiment consisted of two parts. In one, integrated mean air space was maintained at 0.15 cm.3 per cm.3, while densities ranged from about 1.2 to 1.6 g. per cm.3, resulting in integrated mean soil moisture tensions from 0.01 to 5 bars; in the other, for the same densities, mean soil moisture tension was 0.7 bar, and consequently mean air space ranged from about 0.32 to 0.09 cm.3 per cm.3 In almost every case there was a significant negative correlation between total nutrient absorbed per plant and increasing soil moisture tension. Total nutrient absorbed by the plant was independent of density as long as soil moisture tension was 0.7 bar, even though density and air spaces were maintained over a wide range. Likewise, except for boron and phosphorus, a positive correlation was found between concentration of nutrient absorbed at time of harvest and soil moisture tension. No significant correlation existed when soil moisture was maintained at 0.7 bar.
Effect of pH on the Sodium‐Calcium Exchange Equilibria in Soils
Authors: Pratt P. F. , Whittig L. D. , Grover B. L.
Published: July 2010

The Na‐Ca exchange equilibria in 10 acid soils were measured at pH values of 5, 6, 7 and 8 and the results related to a theoretical ion exchange equation based on the Poisson‐Boltzmann differential equation of the electrical double‐layer. The theoretical equation satisfactorily predicted the relative change in ratio of adsorbed Na to adsorbed Ca as the pH of the equilibrium solutions decreased. The actual values of ratios of adsorbed Na to adsorbed Ca agreed with the theory when the surface charge densities for each soil were multiplied by an appropriate factor. This factor varied from 1.0 to 2.1 but was the same for all pH values for a given soil.
Soil Development in Relation to Loessial Deposition in Southeastern Minnesota
Authors: Foss J. E. , Rust R. H.
Published: July 2010

The soils of southeastern Minnesota and adjacent areas are found to be developed mainly on loessial parent material of Wisconsin age. The origin, distribution, and some properties of the loess were studied. Loess deposition in southeastern Minnesota was found to have a general relationship to distribution of the major river valleys of the area. Measurements of loess thickness, determination of particle size analysis, and of calcium carbonate distribution provided evidence for this conclusion.

The characteristics of two loess‐derived profiles developed under forest cover were studied. The profiles were selected to represent a range in degree of horizon development. The differences in profile development appear to be largely the result of weathering time.
A Test for Natural Soil Groups Within the Willamette Catena Population
Authors: Pomerening J. A. , Knox E. G.
Published: July 2010

A sample of 114 soil individuals, from Marion County, Oregon, representing the five soil series of the Willamette catena, was tested for the existence of natural soil groups. Natural soil groups are those separated by minima in frequency distributions of single or combined soil characteristics.

Eighty‐five morphological, chemical, and physical properties were quantitatively measured on each individual. Frequency distributions were tabulated for each property and examined for the presence of minima. Frequency distributions for depth to evidence of impeded drainage, cation‐exchange capacity of the B2 horizon, and exchangeable magnesium of the B3 horizon showed minima.

Discriminant function analysis was used to test the combined differentiating abilities of several selected characteristics. Minima were observed in frequency distributions for those combined functions which included a differentiating characteristic. The natural groups separated by these minima corresponded to the recognized soil series.
Effects of Rainfall Energy on the Permeability of Soils
Authors: Sor Kamil , Bertrand A. R.
Published: July 2010

The effects of simulated rainfall on the air and water permeabilities of sand and several disturbed soil samples were investigated. Various rainfall intensities were provided by a rainfall simulator. Soil was packed in a cylindrical infiltrometer, to which was connected eight manometers. Permeability of the soil to water was measured during and after the application of rainfall.

It was found that a rainfall of 30 minutes duration at an intensity of 2.8 inches per hour caused maximum change in water permeability of the soils. Water permeability of quartz sand was not changed by rainfall. Water permeability of soils was changed; (a) only in top 1.5 cm. by 1.6 inches per hour rainfall, (b) greatly in top 1.5 cm. and somewhat less in second 1.5 cm. layer by 2.8 and 4.0 inches per hour rainfall. In saturated soil columns, water permeability was not governed entirely by the permeability of the least permeable layer. The thickness of the dispersed and compacted soil layer appeared to be about 1 mm. Below it a less compacted layer, about 3 cm. deep, resulted.
Mechanical Impedance and corn Seedling Root Growth
Authors: Phillips R. E. , Kirkham Don
Published: July 2010

Using needle penetration and bulk density as measures of mechanical impedance, the effects of mechanical impedance on corn seedling root growth were studied in the laboratory. The corn seedlings were grown in artificially compacted samples of a Colo clay where the moisture was at a tension of 10 cm. in some samples and 100 cm. in others. The rate of corn seedling root elongation decreased linearly as bulk ensity of Colo clay increased from 0.94 g. per cc. to 1.30 g. per cc., or as needle penetration into the Colo clay decreased. In ohter laboratory experiments, the depth of corn seedling root penetration into sand contained in glass tubes of differing diameters was found to be linearly related to the depth of penetrometer penetration.
The Temperature Effect on the Equilibrium Energy Status of Water Held by Porous Media
Authors: Wilkinson G. E. , Klute A.
Published: July 2010

Water held in porous media is under the influence of a number of forces. The energy of the water in these force fields may be described with the aid of the potential theory of classical physics or with the aid of classical thermodynamics. Desorption curves were determined for two sand fractions and a silt fraction at 48° and 44°C. Temperature coefficients of the potential calculated on the basis that surface tension‐radius of curvature was the principle water‐holding mechanism were compared with the experimental observations. The results indicated that in the fine sand (53–74µ) and silt (13.5–18.0µ) other mechanisms besides surface tension‐radius of curvature may be involved in holding the water in the porous medium.