bluuebunny/crossref_metadata_2025 huggingface dataset:
Carbon Dioxide from Plant Roots as a Factor in the Replacement of Adsorbed Sodium in Calcareous Soils
Authors: Goertzen J. O. , Bower C. A.
Published: July 2010

The effects of CO2 from plant roots in facilitating the dissolution of CaCO3 and the reclamation of sodic soils was studied by comparing the HCO3‐ concentrations of leachates and the less of adsorbed Na from pots of cropped and uncropped soils receiving uniform leaching with salt‐free water. It was found that the effect of CO2 on the replacement of adsorbed Na was measureable but small, and of less importance than the effect brought about by the hydrolysis of CaCO3 upon leaching. Data were obtained which indicate that alfalfa roots release more CO2 than Rhodesgrass roots, and that more of the CO2 is retained in the soil at high moisture levels than at low moisture levels.
Soils, Paleosols, and Soil‐Horizon Nomenclature
Authors: Ruhe R. V. , Daniels R. B.
Published: July 2010

Exhumed paleosols commonly occur geographically juxtaposed to modern soils. Use of standard soil‐horizon nomenclature, with its inherent genetic bias, may erroneously portray the histories of the juxtaposed pedo‐geologic soil landscapes. It is suggested that the nomenclature of exchumed paleosols be differentiated from the nomenclature of modern soils by insertion of an upper case P preceding the letter designations of the soil horizons of exhumed paleosols. Application of the proposed nomenclature is illustrated.

Lithologic discontinuities of parent materials in which a solum has developed now is designated nomenclaturewise by the use of the subscript u—meaning unconformity. This is a misuse of the term unconformity in the geologic sense. In most cases the superposed parent materials are related conformably rather than unconformably. The vertical sequence of Roman numerals to indicate changes in parent materials, suggested by the Committee on Soil Horizons, adequately handles the problem. Application of the sequence is illustrated.
Variations in Forest‐Derived Soils Formed from Kansas Till in Southern and Southeastern Iowa
Authors: Prill R. C. , Riecken F. F.
Published: July 2010

Field and laboratory studies were made of forest‐derived Lindley soils formed from Kansan till. Five variants in the present Lindley series were recognized, indicating the wide range in morphological, physical, and chemical characteristics of the series as presently defined. This range was somewhat comparable to the range in properties observed for Gray‐Brown Podzolic soils formed from Wisconsin loess, which range in stage of development from minimal to maximal.

The ratio of exchangeable calcium to magnesium did not show a consistent relationship with content of clay in the B2 of the Lindley variants. Neither was there a consistent relationship between content of free iron and clay content in the B2. As several of the Lindley variants have ferretto zones coinciding with the designated B2 layer, the lack of precise relationships between exchangeable cations with clay seems to be related to their burial with loess, and resaturation with bases.

There is an apparent relationship of increasing degree of horizon development with decreasing slope for the Lindley variants. However, this is not a simple sequence relationship with topography, as time as well as possibly parent material are also important variables.

Evidently the present Lindley series needs to be subdivided into a number of series.
Relationships of Particle and Pore Sizes to the Growth of Sunflowers
Authors: Miller Scott A. , Mazurak A. P.
Published: July 2010

Sunflowers (Helianthus annuus, L.) were grown in 20 compacted soil separates, ranging in diameters from 4,760 to 2.31µ, which contained pores of diameters between 529 to 2.23µ. Two moisture levels, 20‐cm. water tension and moisture content at “flex point,” were imposed on the 20 separates. Nutrient solution was applied to the separates.

Noticeably different growth rates of sunflowers were measured at the two moisture levels. Maximum rate of stem elongation at 20‐cm. water tension was nearly three‐fold greater than was that at “flex point” moisture percentage. Maximum growth of sunflowers at 20‐cm. water tension was obtained from separates between 52.3 and 210µ in diameter or pores with mean diameters of 17.7 to 43.5µ. Optimum growth of sunflowers at “flex point” moisture was on separates 13.1 to 9.25µ in diameter whose pores were about 4µ in diameter. Aeration appeared to limit the rate of stem elongation when air occupied less than 4% of the pore space.

Maximum growth rate of sunflowers at both moisture levels apparently was determined by the influence of pore size upon aeration and area of root‐solution contact. The greater the area of root‐solution contact, as determined by pore size and moisture tension, the more favorable was the growth of roots and shoots, provided aeration was not limiting.
Some Tests of the Similar Media Concept of Capillary Flow: I. Reduced Capillary Conductivity and Moisture Characteristic Data
Authors: Klute A. , Wilkinson G. E.
Published: July 2010

Plainfield sand was dry‐sieved into the following five size fractions: 104 to 125, 125 to 149, 149 to 177, 177 to 210, and 210 to 250µ. The bulk densities of the sand fractions, when packed in a standard manner, averaged 1.65 ± 0.01 g. per cc. The particle densities of the fractions averaged 2.61 ± 0.01 g. per cc. The size distribution of each fraction was determined microscopically. The bulk density, particle density, and the reduced size‐distribution curves indicated that the sand fractions could be considered similar media.

Capillary conductivity as a function of the moisture tension was determined. When the reduced conductivity was plotted against the reduced tension, the data coalesced into one curve within the limits of experimental error. Moisture characteristic curves of the sand fractions also coalesced into one curve when the reduced tension was plotted against the volume moisture content. The results of this study seem to support the similar media concept.
Inositol Hexaphosphate: III. Content in Soils
Authors: Caldwell A. G. , Black C. A.
Published: July 2010

Samples of 49 soils were analyzed for inositol‐hexaphosphate phosphorus in the meso form and a supposed isomer of this form. Anion‐exchange chromatography was used to make the separations. The quantities of phosphorus present in the two isomers were correlated (r = 0.73), the phosphorus in the supposed isomer averaging 46% of that in the meso form. The total inositol‐hexaphosphate phosphorus averaged 39γ per g. of soil and made up an average of 17% of the total organic phosphorus with a range from 3 to 52%. Of the factors examined, the content of organic phosphorus in forms other than inositol hexaphosphate provided the best prediction of inositol‐hexaphosphate phosphorus. After the quantities of this noninositol‐hexaphosphate organic phosphorus had been taken into account, the soil pH and content of free iron oxide were not of significant independent value in predicting the content of inositol‐hexaphosphate phosphorus. The percentage content of inositol‐hexaphosphate phosphorus in the organic phosphorus was higher in soils developed under forest vegetation (24%) than under grassland vegetation (14%) and decreased with increasing pH in both types of soils. The ratio of inositol‐hexaphosphate phosphorus to other forms of organic phosphorus averaged the same in samples of 10 cultivated soils as in samples of the corresponding virgin soils, thus indicating that the inositol‐hexaphosphate phosphorus decomposed at about the same rate as the other forms of organic phosphorus.
Temperature‐Time Curves as Soil Freezes Related to Moisture‐Stress Curves
Authors: Evans D. D. , Horrigan J. A. , Chinn C. E.
Published: July 2010

The rate of cooling of a moist soil sample during freezing is determined by the rate of heat dissipation to the surroundings and the rate of ice formation with the sample. Assuming equilibrium conditions at an instantaneous temperature, the amount of ice formed between two temperatures depends upon the amount of water held in the sample between the soil moisture stresses associated with the two temperatures.

Temperature‐time curves (freezing curves) during freezing have been obtained for soils using a thermistor and recording potentiometer. The curves have been related to moisture‐stress curves derived through the use of standard pressure apparatus. A method is presented which may allow the construction of a moisture‐stress curve from one freezing of a single sample of soil.
Effect of Crop Rotation and Fertilizer Treatment on the Nitrogen and Organic Carbon Contents of a Prairie Soil
Authors: Fritschen Leo J. , Hobbs J. A.
Published: July 2010

The effects of cropping systems and soil treatments on the nitrogen and organic carbon contents of Geary silt loam were studied in 1915, 1923, 1934, 1946, and in 1956 on the Agronomy Farm at Manhattan, Kansas.

Losses of nitrogen and organic carbon were largest where the original contents of these constituents were highest. Losses were most rapid in the earlier years of the study. Largest losses occurred under a 3‐year rotation of corn, soybeans (for hay), wheat. Losses tended to be lower in the continuous wheat plots than in plots under rotations including row crops and legumes in addition to wheat.

Differences between losses of nitrogen and organic carbon under the different fertility treatments were small. However, losses were greatest under phosphate, and phosphate and potash treatments, and were smallest under the complete fertilizer treatment.

Although alfalfa increased the nitrogen content of the subsoil slightly, the other crops in the rotation reduced it so that the rotation studied did not appreciably change the subsoil nitrogen content.
Determination of Available Potassium in Soils of Forest Plantations
Authors: Leaf Albert L.
Published: July 2010

Various soil biological and chemical tests were compared in respect to their suitability for predicting deficiency of potassium for red pine grown on soils of Wisconsin and New York. The biological tests were accomplished by the Azotobacter and Aspergillus niger methods. The chemical tests included extraction of soil by N NH4OAc of pH 6.9 and 4.6, extraction by N NH4NO3 of pH 6.9 and 4.0, extraction by 0.4 N HCl, ignition of ammonium‐saturated soil followed by extraction with neutral N NH4OAc, and extraction with boiling N HNO3. The last method provided the sharpest distinction between potassium‐deficient and nondeficient forest soils as detected by the rate of growth and response of plantations to application of potash fertilizers.
Influence of VAMA and of Depth of Rotary Hoeing upon Infiltration of Irrigation Water
Authors: Bodman G. B. , Johnson D. E. , Kruskal W. H.
Published: July 2010

Long continued inter‐row cultivation and passage of vehicles may adversely affect soil physical properties. The influence upon infiltration in peach orchards of the incorporation of vinyl acetate maleic anhydride (VAMA) with sandy loams which had been harmed by such treatments was studied during three irrigation seasons after a single addition of the VAMA polymer in 1953.

Treatments were: rotary hoe cultivation to depths of 1, 6, and 16 inches, with and without polymer incorporation; soil then undisturbed and kept weed‐free. Polymer influence persisted through three seasons. Average depths of infiltered water after 1.6 hours for all cultivation depths were: without polymer, 3.1 in.; with polymer, 6.2 in. Where polymer was incorporated, increased cultivation depth gave increased infiltration; without polymer, cultivation depth appeared to have no appreciable effect. Supplementary measurements following tractor passage in 1955 showed average decrease in infiltration at 1.6 hours from 7.0 in. (without tractor) to 2.4 in. (with tractor).

Dispersing tendency, density, and moisture characteristics are presented for soil cores taken from one orchard at the end of the third season. The increased aggregate stability in water and lowered bulk density of cores taken from soils receiving polymer, persisted until the end of the experiment. Treatments considerably influenced moisture retention and hence pore volume at tensions less than 1/5 atm. but, with the exception of the tractor‐compacted, deeply‐tilled, with‐polymer treatment, they had little effect upon these properties at higher tensions. The cumulative depths of infiltered water were clearly associated with changes in volume of coarser pores.
Application of Phase Rule to the Chemical Behavior of Monocalcium Phosphate Monohydrate in Soils
Authors: Brown Walter E. , Lehr James R.
Published: July 2010

When a granule of monocalcium phosphate monohydrate, Ca(H2PO4)2 · H2O, dissolves in a soil system, the fraction, f, of the phosphate left at the site of the granule as a dicalcium phosphate, CaHPO4 or CaHPO4 · 2H2O, is shown by the relation

f = (1 − R)/(2 − R)

where R, the mole ratio of CaO/P2O5 in the composite solution removed from the granule, can be determined experimentally or estimated from phase‐rule data for the system CaO‐P2O5‐H2O. The composition of the solution leaving the granule approximates the invariant‐point solution in equilibrium with Ca(H2PO4)2 · H2O and either CaHPO4 (the stable invariant point) or CaHPO4 · 2H2O (a metastable invariant point).

Equilibrium data from the literature suggest that a residue of CaHPO4 will contain some 28% of the P. Experimental data are presented from which a residue of CaHPO4 · 2H2O is predicted to contain about 21% of the P.

Reaction of some of the solute phosphate with cations such as iron and aluminum can cause precipitation of additional calcium phosphate.
Nature of the Reactions of Monocalcium Phosphate Monohydrate in Soils: II. Dissolution and Precipitation Reactions Involving Iron, Aluminum, Manganese, and Calcium
Authors: Lindsay W. L. , Stephenson H. F.
Published: July 2010

TPS, the solution in equilibrium with monocalcium phosphate monohydrate (MCP) and anhydrous dicalcium phosphate, was reacted with successive increments of Hartsells fine sandy loam (pH 4.6) and Rosebud loam (pH 7.6). The experiments were designed to simulate chemical conditions that may occur in soil surrounding a dissolving granule of MCP.

Reaction of soil with TPS (pH 1.01, 4.50M P, and 1.34M Ca) resulted in the dissolution of Fe, Al, Mn, Ca, and other constituents from the soil. As successive soil increments were contacted by the solution, simulating its movement from a fertilizer granule, the dissolution processes continued and pH of the solution increased. The solution soon became supersaturated with respect to certain phosphate compounds that slowly began to precipitate.

During these reactions with Hartsells soil, Al in solution reached 0.7M, Fe 0.2M, and Mn 0.009M. With Rosebud soil, the concentrations of Fe and Al were slightly less. TPS in contact with soil dissolved Mn more readily than Al, and Al more readily than Fe. With time and rise in pH, the precipitation of these cations was in the order Fe > Al > Mn. Most of the filtrates obtained from reaction of soil with TPS precipitated solids upon standing. Some of these solids were identified by microscopic and X‐ray analyses as crystalline Fe, Al, or Ca phosphates, while others were colloidal, amorphous precipitates that were not identifiable by these methods.
A Method for Measuring Short‐Term Nutrient Absorption by Plants: II. Potassium
Authors: DeMent Jack D. , Stanford George , Bradford B. N.
Published: July 2010

The method previously reported for measuring short‐term P absorption by plants has been adapted to studies of K uptake in relation to various factors. K‐deficient oat or corn plants, grown in sand cultures, were placed in contact with soil or soil‐fertilizer mixtures for periods of 1 to 14 days. Recovery in oat tops from applications of 10 to 120 mg. K ranged from 25 to 7% in 3 days to 63 to 30% in 14 days. When K content of roots in sand and in soil also was taken into account, 14‐day recoveries from 30‐ and 120‐mg. K additions were 85 and 43% respectively. Despite the wide range in K content of plants, growth differences among treatments were not apparent for at least the first week, as had previously been observed in studies with P.

Unfertilized soils supplied significant amounts of K to plants in 3 days. At 7 days, rather wide differences in K content of plants were evident among soils, indicating the possible utility of the method in assessing the K status of soils. Moisture contents of soils were important in relation to K uptake. Moisture equivalent for each soil appeared to be the near‐optimum level.

Availabilities of K in potassium calcium pyrophosphate (KCP), potassium metaphosphate (KMP), and KCl to corn plants were compared in soil and sand. During 1‐ and 3‐day absorption periods, KCl was more available than KMP and KCP in both media. The data suggest that contact with soil increased dissolution of the KMP and KCP. KCl was less available in soil than in sand.

Very high correlations were found between uptake of K by tops and whole plants for a wide range of K rates, absorption periods, and soils. Thus, K content of plant tops is a suitable criterion for assessing relative effects of treatments on K nutrition of the plants.
The Occurrence and Distribution of Lime in Calcium Carbonate Solonchak and Associated Soils of Eastern North Dakota
Authors: Redmond C. E. , McClelland J. E.
Published: July 2010

Calcium Carbonate Solonchaks occur in close association with Chernozems and Humic‐Gley soils. Profiles have A1‐Cca‐C horizon sequence and form in calcareous parent materials. Evidence is presented to show that the prominent Cca horizon results form the precipitation of lime out of capillary water rising or moving laterally from a zone of water saturation.
Fragipan Soils of Illinois: III. Micromorphological Studies of Hosmer Silt Loam
Authors: Grossman R. B. , Stephen I. , Fehrenbacher J. B. , Beavers A. H.
Published: July 2010

Micromorphological studies of Hosmer silt loam, a bisequal soil with a fragipan, indicate that the B2 horizon of the upper sequum is at present an apparently stable, non‐illuvial horizon, whereas the B horizons of the lower sequum are apparently illuvial in character, and in the process of degradation to form the encroaching A′2 horizon. An attempt is made to relate resistance to rupture of the major horizons to their micromorphology.
Estimation of Hydrateable Surface Area of Soils and Clays from the Amount of Absorption and Retention of Ethylene Glycol
Authors: Sor Kamil , Kemper W. D.
Published: July 2010

A modification of the glycol retention method for estimating hydrateable surface areas is proposed. In this modification, a large amount of glycol‐bentonite mixture, containing just enough glycol to form a monolayer on all bentonite surfaces, is used to “buffer” the glycol vapor pressure in an evacuated desiccator. Dry and glycol‐saturated samples placed in the desiccator then gain and lose glycol, respectively, until approximately a monolayer exists on all hydrateable surfaces at equilibrium. The average amount of glycol on the two samples at this equilibrium is used, as in previous glycol retention methods, to estimate the hydrateable surface area.

The Bower and Gschwend procedure is used to estimate the amount of glycol necessary to form a complete monolayer on all surfaces of the bentonite to be used in the buffer mixture. This amount of glycol is much easier to estimate in a fairly pure clay with large, well characterized surface area than in soil samples, and some possible errors of former techniques may be avoided by the proposed procedure.
The Nitrogen Status of the Mineral Soils of Florida
Authors: Pritchett W. L. , Eno C. F. , Malik M. N.
Published: July 2010

Surface soil samples were collected from the major soil types and cultural practices in the state and analyzed for organic matter, total N and nitrate produced during 2 and 6 weeks of incubation. Correlation coefficients were determined among these properties after grouping the soils according to cultural practice and soil texture. The average organic matter and total N content of Florida mineral soils were 2.52 and 0.060%, respectively. Nitrate produced in 2 and 6 weeks of incubation averaged 21 and 42 ppm., respectively. All three of these constituents increased with increases in fineness of soil texture. Cultural practices also had an influence on these properties. In general, a highly significant relationship was found between total N and organic matter, and total N and nitrate production. However, a significant relationship between organic matter and nitrate production occurred only for certain of the cultural and textural groups with a higher degree of correlation at the end of 6 weeks than at the end of 2 weeks.
Recovery of N15‐Tagged Nitrogen from Ammonium‐Fixing Soils
Authors: Legg J. O. , Allison F. E.
Published: July 2010

The uptake by Sudangrass of N applied to two ammonium‐fixing subsoils at rates ranging from 0 to 400 pounds per acre was similar to the uptake from a nonfixing surface soil. N uptake from NaNO3 and banded (NH4)2SO4 was higher than that from (NH4)2SO4 mixed throughout the fixing soils, but the differences could not be attributed entirely to ammonium fixation. Where (NH4)2SO4 was mixed with the soil, A values calculated from the N15 data appeared constant for all N rates. A N‐balance sheet prepared from analyses of soil and plant materials accounted for 93.6% of the N15‐tagged fertilizers as an average of all soils and treatments.
Relative Release and Retentiveness of Soil Phosphates
Authors: Shapiro Raymond E. , Fried Maurice
Published: July 2010

A kinetic equation is derived in terms of reaction products assuming a pseudo first order displacement of Soil‐P by hydroxyl ion. Application of this equation to a Bridger silt loam by means of a nonequilibrium leaching system indicated at least two forms of soil P based on rate of release: (a) a rapidly released form which quickly diminishes with time, and (b) a more slowly released form which is relatively constant with time. An equation is also derived for the equilibrium adsorption of P on the soil surface from a soil‐water system. Caribou, Bridger, Davidson, and Nibley soils were equilibrated with solutions of varying P concentrations at constant volume. The results were plotted using moles of P adsorbed as ordinate vs. the moles of P adsorbed divided by the equilibrium P solution concentration as abscissa. The data again indicated at least two forms of soil P, one tightly held and one relatively loosely held. At constant solution volume, equilibration of 1, 2, and 4 g. of Caribou soil with solutions of varying P concentration, indicated that the apparent dissociation constant for each site and the maximum amount of P that may be adsorbed per gram of soil by each site are both independent of the weight of soil used. The characterization of the soil P system by this equilibrium method is independent of soil/solution ratio in the range of 1:5 to 1:2000.
Hypotheses Concerning Iron Chlorosis
Authors: Brown J. C. , Holmes R. S. , Tiffin L. O.
Published: July 2010

Iron chlorosis was studied in two plant species grown on calcareous Quinlan, Tripp, and Millville soils. Two types of Fe chlorosis developed: (1) Iron deficiency accentuated by improper microelement balance appeared to be the causative factor controlling the development of Fe chlorosis in milo grown on Quinlan and Tripp soils. The Cu uptake by milo from all three soils and two NaDTPA chelate treatments was more than double that taken up by PI‐54619‐5‐1 and Hawkeye soybeans. The Fe/Cu + Mn ratio was much lower in the soil extracts of Quinlan and Tripp than the Millville soil. (2) An abundance of available P and Ca appeared to be the controlling causative factors of Fe chlorosis in PI‐54619‐5‐1 soybeans grown on the Millville soil. PI‐54619‐5‐1 and Hawkeye soybeans differed in their susceptibility to this type of chlorosis. It was suggested that new chlorosis‐resistant varieties through plant breeding, Fe chelates economically feasible for field application, controlled fertilizer, water, and cultural practices might all lend themselves to correcting Fe chlorosis in the field.
Some Characteristics of Clay Skins on Peds in the B Horizon of a Gray‐Brown Podzolic Soil
Authors: Buol S. W. , Hole F. D.
Published: July 2010

Clay coatings or skins were removed from peds in the B3 horizon of a Gray‐Brown Podzolic soil of southern Wisconsin. Analyses were made to determine the contents, both in the clay skins and in the entire horizon, of N, C, clay, reductant‐soluble Fe, total Fe, Al, Na, K, Ca, Si, Mg, and Ti. Thin sections were made of peds from the B3 horizon and were examined with the aid of a petrographic microscope to determine the structure of the clay skins.

The results of analyses for the clay skins show relatively high contents of N (0.11%), C (1.836%), clay (87.4%), free Fe (2.76%), as compared with contents in the bulk sample from the B3 horizon: 0.029% N, 0.417% C, 24.3% clay, and 1.33% free Fe. X‐ray diffraction patterns showed that the clay in the bulk sample contained slightly more chlorite and slightly less vermiculite and chlorite‐vermiculite intergrade than the clay of the clay skin. Microscopic thin‐sections of clay skins showed a mean clay‐skin thickness of 0.079 mm., with component lamellae each 0.007 to 0.010 mm. thick.
Conducting Successful Irrigation Research
Authors: Robins J. S.
Published: July 2010

This paper summarizes factors to consider in conducting successful irrigation experiments. Research is considered in three phases—planning of the experiment, conduct of the experiment, and publication of results. Pertinent points relative to these three phases are summarized indicating why each is important and some principles to be followed in each phase.
A Study of the Sodium Adsorption Ratio and Residual Sodium Carbonate Concepts of Irrigation Waters as They Affect Exchangeable Sodium of Soil Under Semiarid Conditions
Authors: Fine L. O. , Williamson E. J. , Wiersma Frank , Umback C. R.
Published: July 2010

The object of this study was to investigate the significance of “residual Na2CO3,” as engendered by high HCO3‐ content in irrigation water, using synthetic and natural waters in greenhouse experiments, and a natural water in a field experiment. The significance is evaluated in terms of exchangeable Na+ changes in soils on which the waters were applied.

Synthetic waters and unadulterated natural waters of high HCO3‐ content produced exchangeable‐sodiumpercentages (ESP) in greenhouse cultures 4 to 6% above that expected from the sodium‐adsorption‐ratio (SAR) value of the waters used. The use of gypsum with natural waters held the ESP to approximately 2 to 4% above that predictable from the SAR‐ESP nomogram.

A field experiment of 5 years' duration with natural and gypsum‐treated reservoir water under conditions of about 15 inches annual rainfall resulted in exchangeable Na+ levels much lower than those found in greenhouse experiments. This occurred, even though more than twice as much water was used. The highest ESP level found was 2% below that expected from the SAR value of the water.

The apparent discrepancy between field and greenhouse results can be ascribed in part to Ca return to the soil surface by alfalfa and possibly to slow weathering of noncarbonate minerals. There was a decrease in exchangeable H+ during the 5‐year field experiment.
Determination of Aluminum Ion Activity in Soil Extracts
Authors: Lindsay W. L. , Peech Michael , Clark J. S.
Published: July 2010

A method is presented for calculating the Al3+ ion activity from measurements of the concentration of Al, pH, and the ionic strength of the soil extract. The colorimetric method for determining the concentration of Al in soil extracts makes use of the aluminon reagent with provisions for removing organic matter and silica and for preventing the interference of Fe by the addition of thioglycollic acid.

The validity of the method was established by verifying the existence of a theoretical equilibrium relationship between the Al3+ and the H+ activities in soil extracts. The value of (pH — ⅓ pAl) for CaCl2 extracts of three acid soils was found to remain remarkably constant as the concentration of CaCl2 in the extracting solution was increased from 0.001 to 0.10M. This constancy of (pH — ⅓ pAl) for soil extracts can be predicted from the Donnan and Gouy theories and does not necessarily indicate the presence in the soil of some crystalline form of hydrous aluminum oxide having a definite solubility product.
Effect of Potassium and Calcium Activities in Clay Suspensions and Solutions on Plant Uptake
Authors: Bartlett R. J. , McLean E. O.
Published: July 2010

The clay membrane electrode was used to evaluate average activities of K and Ca in clay suspensions and in solutions throughout an 11‐day growth period. Uptake of K and Ca by soybeans, barley, and buckwheat was compared in bentonite and Putnam clay suspensions and in solutions with the same cationic activities. The media were changed frequently to maintain relatively constant K and Ca activities. The other essential elements were supplied by periodically placing the plants in solutions containing Mg, N, P, S, and Fe.

In soybeans and barley, both yield and percentage of K were higher in clays than in solutions of equal or even higher activities, but were not significantly different between clays. At the levels tested, K uptake was more closely related to total amount present than to activity. Thus, there was no evidence that bonding of exchangeable K regulated uptake.

On the other hand, it was shown that bonding of Ca by clays may have regulated uptake. All plants removed as much or more Ca from solution as from suspension of equal activity. In soybeans, uptake of Ca was proportional to the Ca activity in the medium, while in barley and buckwheat, Ca uptake of this element was greater from solution than from clays, even when the Ca activities in both media were equal. The order of Ca accumulated was buckwheat > soybeans > barley. Some evidence was noted for contact interaction between root and clay colloids in both K and Ca uptake.
Effect of Liming and Organic Matter Content on the Availability of Native and Applied Manganese
Authors: Sanchez Carlostadio , Kamprath Eugene J.
Published: July 2010

A large amount of the soluble Mn added to soils was rapidly converted to nonexchangeable forms in both incubation and field studies. The addition of lime further decreased the amount of exchangeable Mn (NH4OAc‐extracted). The acid‐extractable Mn content of the soil showed no decrease at the end of 3 weeks' incubation but did after 6 weeks' incubation.

The moisture content of the sample previous to extraction had an effect on the exchangeable Mn content. Less exchangeable Mn was extracted when the soil was kept moist after the sample had been taken than when it was first air‐dried. This effect was most pronounced on a high organic matter soil which had been limed.

The addition of peat to a low organic matter soil increased the exchangeable Mn conent of the acid soil when maintained in a moist condition. The peat caused a decrease in the acid‐extractable Mn in the limed soil.
Plant Growth as Affected by Ethylene Dibromide Fumigation of Soils at Two Moisture Levels
Authors: Brown A. L. , Jurinak J. J. , Martin P. E.
Published: July 2010

Ethylene dibromide (EDB) was injected into Yolo loam, Yolo clay, and Staten peaty‐muck at two moisture levels (air‐dry and field capacity) at rates of 0, 0.01, 0.02, 0.05, 0.1, 0.5, 1.0, and 5.0 ml. per crock. The soils were allowed to stand for 2 weeks before transplanting tomato seedings into them. The moisture level was then maintained adequate for growth.

The phytotoxicity of EDB was particularly marked in the air‐dried soils, indicating greater retention of the fumigant vapor in the dry system as compared to the soils maintained at field capacity. The total Br taken up by the plants was generally greater from the moist soils than from the air‐dry soils although the concentration in the plants was in reverse order. The concentration of Br in the plant increased with increasing rates of EDB. Analyses of the soils for water‐soluble inorganic Br indicated there was more soluble Br in the soils maintained at field capacity than in those kept air‐dry.
Specific Surface Determination by Duo‐Interlayer and Mono‐Interlayer Glycerol Sorption for Vermiculite and Montmorillonite Analysis
Authors: Mehra O. P. , Jackson M. L.
Published: July 2010

In a new method for specific surface determination, montmorillonite is made to sorb exactly two interlayers of glycerol (a true monolayer on each planar surface) at 35° C. in a vacuum of < 1 mm. of Hg. Vermiculite sorbs only one interlayer under these conditions. Both montmorillonite and vermiculite sorb only a mono‐interlayer of glycerol at 110° C. in a previous method. The two analytical methods thus give the amount of glycerol corresponding to the second interlayer in montmorillonite, and this makes possible quantitative analytical determination of montmorillonite and of vermiculite.

To illustrate, Wyoming montmorillonite sorbs 21.1% glycerol at 110° C., and 41.6% at 35° C. in vacuum, which gives an analysis of 98% montmorillonite, whereas Colorado vermiculite sorbs the same amount of glycerol under both these conditions, equivalent to only a monointerlayer. The presence of fine amorphous material in montmorillonitic fine clays is revealed by a higher specific surface than obtained with 100% montmorillonite. Dissolution of the allophane from Black Cotton soil (India) resulted in a specific surface analysis of 94% montmorillonite (5 to 10% kaolinite is present). Ladybrook fine clay fraction (Queensland, Australia) showed 90% montmorillonite and 10% of mono‐interlayer expanding mineral.
Release of Fixed Potassium as a Diffusion Controlled Process
Authors: Mortland M. M. , Ellis Boyd
Published: July 2010

Rate of release of fixed K from vermiculite with 0.1N NaCl was studied to attempt to characterize the ratelimiting process. Of the processes considered, film diffusion satisfied most criteria as rate limiting. The activation energy of the release of K by 0.1N NaCl in the system studied was about 3,550 cal./mole, a value of the order frequently obtained for diffusion processes.
Effect of Nutritional Stress on Plant Composition: I. The Interaction of Added Nitrogen with Varying Sulfur Supply
Authors: Rendig V. V. , McComb E. A.
Published: July 2010

Greenhouse and laboratory experiments with alfalfa as the test plant were designed to test the hypothesis that minimum levels of certain plant metabolites may occur at an intermediate stage of nutritional stress. This possibility in the case of S was indicated by results which had been obtained for amide and free amino N in alfalfa hay and appeared to be at variance with reports in the literature that accumulation of these N fractions are symptoms of S deficiency.

Several levels of S both with and without applied N were used. Because of the sensitivity of Rhizobia activity to pH, CaCO3 was added to keep the reaction of the medium in a favorable range at the varying nutritional levels. Plants were obtained by rooting cuttings from a single clone and were grown in both soil and liquid cultures. Physiological age at time of harvest was identified by flower development.

Since physiological studies indicate the importance of carbohydrate/nitrogen ratios, reducing and total sugars were determined as well as several N fractions. The implication of the findings in terms of nutritional stress effects are discussed.
Report on Flame Photometric Determination of Exchangeable Mangesium in Soils
Authors: Attoe O. J.
Published: July 2010

Twelve soil samples, varying from about 40 to 1600 ppm. of exchangeable Mg, were analyzed for this constituent by collaborators at 13 state and federal laboratories. Twelve laboratories used the Beckman flame photometer and one laboratory the standard AOAC method. All laboratories followed the same extraction procedure, and at 7 of these the determinations were made by two operators. An analysis of variance revealed there were highly significant differences in the results obtained between laboratories and between operators within laboratories. However, in terms of the accuracy usually obtained for Mg by other methods, there was fairly good agreement between laboratories and between the flame photometric and AOAC methods.
Influence of Certain Soil Fumigation Treatments on the Response of Tobacco to Ammonium and Nitrate Forms of Nitrogen
Authors: McCants C. B. , Skogley E. O. , Woltz W. G.
Published: July 2010

Fertilizer mixtures in which the nitrogen was allammonium, all‐nitrate or equal parts ammonium and nitrate were applied in conjunction with the following soil fumigation treatments: not‐fumigated, Dowfume W‐85 (ethylene dibromide), Shell DD (dichloropropene and dichloropropane), and methyl bromide. Data were obtained on the effect of fumigation and N treatments on (1) the relative levels of ammonium and nitrate N in the soil during the growing season, (2) the ammonium and halogen content in the tobacco leaf at certain stages of growth, and (3) the yield and certain properties of the cured tobacco leaf.

Methyl bromide and Shell DD reduced nitrification to a greater degree than did Dowfume W‐85. Three weeks after transplanting, the ammonium N and halogen contents in tobacco leaves from the ammonium N treatment were higher than from the nitrate N treatment on soil fumigated with Shell DD or methyl bromide, but no different for the Dowfume W‐85 or not‐fumigated treatments.

The yield and quality index of tobacco from the Shell DD and methyl bromide fumigation treatments increased with increasing percentage of the total N applied in the nitrate form. With Dowfume W‐85, the highest yield was from the mixture of ammonium and nitrate N. There were no differences in yield or quality among N treatments on soil not‐fumigated. For all fumigation treatments, the percentage N and percentage nicotine in the cured leaf were higher where ammonium N than where nitrate N was applied.
Some Physical and Chemical Changes in the Soil Brought about by Saturation With Natural Gas
Authors: Adams Russell S. , Ellis Roscoe
Published: July 2010

Severe chemical and physical changes may occur in soils saturated with natural gas. Plant growth may be retarded or completely eliminated.

A study was made of the profile of four gas‐saturated field sites and the adjacent normal soils. Determinations were made for total carbon, available P, pH, exchange‐able Mn, exchangeable ferric iron, and exchangeable ferrous iron. At two sites pH titration curves were determined. A sharp inflection in the curve at pH 2 was observed with gas‐saturated soils. Substantial increases of total carbon, exchangeable Mn, and exchangeable ferric iron occurred in the gas‐saturated soil. Exchangeable ferrous iron increased moderately. Determinations of soil pH and available P gave varied results, but in general showed increases in the gas‐impregnated soils. Physical determinations at the two most severely affected sites revealed some increase in water retention and total porosity with a corresponding decrease in bulk density in the gassaturated soils. The disturbed Fe‐Mn relationships may be one of the major factors accounting for the frequently observed detrimental influence of gas‐saturated soils on vegetative growth. The change in water retention was not considered injurious to the plants.
Effect of Nitrogen Volatilization on Soil Acidity Changes Due to Applied Nitrogen
Authors: Hiltbold A. E. , Adams Fred
Published: July 2010

Nitrogen was applied as urea, NH4OH, (NH4)2SO4, (NH4)H2PO4, (NH4)2HPO4, NH4NO3, and NaNO3 to 10‐, 20‐, and 25‐g. samples of soil and incubated under conditions favorable for nitrification. Glucose was added during incubation to supply energy for denitrification. The samples were later analyzed for pH, NH4+, NO2‐, NO3‐, and organic N. The final acidities and extent of nitrification and volatilization varied considerably, even among identically treated samples. Volatilization losses of N ranged from none to the entire amount applied.

The acidity resulting from nitrification was calculated for each sample and compared to actual acidity. The difference between calculated and observed acidity was accounted for by equivalent N volatilization. This relationship was obtained with 3 soils regardless of the N source applied and the probable gaseous form of loss.
Field Infiltration Studies With Green Manures and Crop Residues on Irrigated Soils
Authors: Williams W. A. , Doneen L. D.
Published: July 2010

The effects of leguminous and gramineous green manure crops and corn and cotton crop residues on soil structure were compared by measuring water infiltration rates in irrigation furrows. Experiments were performed on alluvial soils of widely varying texture, developed in a Mediter‐ranean‐type climate.

Gramineous summer and winter green manures improved infiltration relative to fallow. This benefit was restricted to soils of medium and fine textures. The effectiveness of barley green manure increased as it advanced in maturity. Neither summer nor winter annual legumes influenced infiltration.

Corn crop residue and, to a lesser extent, cotton crop residue were effective in improving infiltration. Corn roots alone also made a significant, but lesser, contribution to improved infiltration.
Turbidimeter Technique for Measuring the Stability of Soil Aggregates in a Water‐Glycerol Mixture
Authors: Davison James M. , Evans D. D.
Published: July 2010

A technique is described for measuring the aggregate stability of soil with mechanical agitation in a waterglycerol mixture. The technique consists of uniformly mixing a weighted soil sample in a 1000‐ml. test tube containing a known water‐glycerol mixture. After uniformly mixing, the test tube containing the suspension is immediately placed in a turbidimeter and the change in light transmission with time at a specific depth is measured using a recording potentiometer. The tube is removed after a specific time and the contents again mixed uniformly by a standard technique and an additional curve obtained. This process may be repeated as many times as necessary to obtain the breakdown trends of the aggregates with mechanical agitation. The mean weightdiameter of the soil aggregates in each run may then be determined by plotting the logarithm of th potentiometer reading vs. the square of the aggregate diameter (as callculated using Stokes' law) and measuring the area under the curve. The change in mean weight‐diameter is a measure of the breakdown of the aggregates due to mechanical agitation in the water‐glycerol mixture. Results show that the method measures differencers in structure not measured by the usual wet‐sieve method.
Use of Wax Substrates in Root Penetration Studies
Authors: Taylor Howard M. , Gardner Herbert R.
Published: July 2010

Basic information on root penetration into pressure pans is essential in soil compaction studies. The ability of plant roots to penetrate compacted zones may determine moisture effectiveness and nutrient availability on these pressure‐pan soils.

The use of wax substrates for simulated plastic pans is discussed and evaluated. Physical characteristics of a number of commercially available waxes are presented.

In plant growth‐chamber experiments using wax substrates, the ability of plant roots to penetrate depended upon the wax rigidity, the type of plant, and the density of the soil above the substrate.
Evidence for Sodium Fixation in Salt‐Affected Soils
Authors: Babcock K. L.
Published: July 2010

Evidence from isotopic dilution studies is presented to show that adsorbed Na in salt‐affected soils may be exchangeable with Na isotopes but nonexchangeable with Ca++ or NH4+ ions. The evidence also shows that a solid form of Na may be present in these soils which disolves in normal extracting solutions but not in water.
The Action of Duramycin on Plant Roots
Authors: Norman A. G.
Published: July 2010

The polypeptide antibiotic, duramycin, has been reported to be antagonistic to certain plant pathogens. Growth of plant roots, however, is repressed by this compound. The duramycin concentration causing 50% reduction in elongation of the primary root of cucumber is 42 µg. per ml. The deleterious effect is mitigated or prevented by simultaneous presentation of calcium or magnesium ions. Depending on concentration, duramycin resembles polymyxin in being bound to plant roots. Roots exposed to excess duramycin lose solutes, both inorganic and organic, and are irreversibly injured. Auxin‐induced water uptake by hypocotyl segments is unaffected by low concentrations of duramycin which does not have antiauxin properties.
Chelating Agent and Plant Nutrient Interactions Affecting the Iron Nutrition of Soybeans
Authors: Tiffin L. O. , Brown J. C. , Holmes R. S.
Published: July 2010

Studies were made to evaluate the effect of absorbed chelating agent on the subsequent absorption‐translocation of iron in soybeans. Iron was separated from the chelating agent by using split‐medium and split‐root techniques.

Chelating agents did have some effect on the absorption of radioiron from Millville soil and the translocation of foliar‐applied radioiron. These effects were not great enough to correct iron chlorosis. Phosphorus in the nutrient medium or within the plant depressed the uptake and translocation of iron by the plant. This effect of phosphorus on iron could not be offset by use of chelating agents. The primary role of iron chelates in plant nutrition appears to be that of making iron soluble and available to the root for absorption.
Water Movement into Soil from I dealized Vertical Mulch Channels
Authors: Swartzendruber Dale
Published: July 2010

A mathematical solution in elliptic integrals is obtained for the flow in a system of channels in water‐saturated, uniform soil, assuming a very highly permeable stratum to exist at finite depth. If water enters the soil through the original soil surface as well as the channel surfaces, the increase in flow due to the channels is generally small. However, if the original soil surface is sealed, the channels are relatively effective in restoring the flow to that which occurs in the absence of the channels and surface sealing. From the analysis there emerges the simple depthspacing formula, d0 = 0.28 S, which is presented as a tentative design criterion for the placement of vertical mulch channels.

Analysis is also made for soil anisotropy in which the horizontal permeability exceeds the vertical permeability. In all cases this increases the flow contributions of the channels.
Elimination of Interference by Phosphorus and Other Elements in the Flame Photometric Determination of Calcium and Magnesium in Plant Tissue
Authors: Wells C. G. , Corey R. B.
Published: July 2010

A rapid, accurate flame photometric method was devised for determination of Ca and Mg in plant tissue. Interferences by P and any Fe and Al that might be present were eliminated by addition of FeCl3 to the acid plant ash extract and precipitation of P, Fe and Al by neutralizing to pH 5.6 with NH4OH. A positive interference by K was corrected by addition of 500 ppm. K to all solutions. NH4OAc was added to prevent clogging of the burner capillary by the NH4Cl solution. Results obtained with the new method agreed well with those obtained with AOAC methods.
Extraction of Soil Organic Matter With Anhydrous Formic Acid
Authors: Parsons J. W. , Tinsley J.
Published: July 2010

Formic acid, being a polar compound, has proved a good solvent for polysaccharides and in the anhydrous condition it exhibits neither oxidizing nor hydrolytic properties. Shaking soil with cold anhydrous formic acid dissolved an appreciable quantity of organic matter but extracted considerably less than did two consecutive ½‐hour boiling periods under reflux. Addition of inorganic cations to the extractant increased its efficiency. Recovery of the dissolved material was attained by precipitation with diisopropyl ether containing 1% CH3COCl which held inorganic cations in solution. Repeated precipitation from formic acid solution yielded a material low in ash with a good physical texture. The N extracted from a wide range of soils varied from 27 to 43% of the total N while for composts the value was as high as 87%. The yield of organic material represented from 27 to 39% of the total organic matter for the soils and 80% for the compost.