bluuebunny/crossref_metadata_2025 huggingface dataset:
Radioactive Phosphorus and the Growth and Metabolic Activities of Soil Microorganisms
Authors: Goring C. A. I. , Clark Francis E.
Published: July 2010

Experiments were conducted in quartz sand and in a silt loam to determine effect of differing levels of P32 on the growth and metabolic activity of soil microorganisms. Determinations were made of carbon dioxide evolved and of numbers of microorganisms, and in some experiments, of amounts of soluble phosphate, nitrate, and ammonia.

In quartz sand treated with phosphorus, dextrose, urea, and mineral salts, and with differing amounts of P32, activity levels of 0.005 and 0.05 mc gave no appreciable differences. At 0.5 mc P32 per mg of P31, the rate of CO2 production was reduced during the first week, and differences in the soil flora were encountered. Recovery in CO2 production then followed, but the soil flora differences persisted throughout 3 weeks of incubation.

In Seymour silt loam treated with 0.5 mc of P32 per mg of P31, there was found no influence on microbial numbers or on carbon dioxide evolution, but the amounts of soluble phosphate, ammonia, and nitrate at the end of 3 weeks were lower than for 0.05‐, 0.05‐, or 0‐mc levels of treatment. When the phosphorus treatment was supplemented with dextrose and urea, no differences in the P or N status of the aliquots could be demonstrated. With dextrose and urea added and a 5.0‐mc level of activity, there was only slight reduction in CO2 evolution and only slight differences in microbial numbers.
The Effect of Cultivation on Erodibility of Soils by Wind
Authors: Chepil W. S. , Englehorn C. L. , Zingg A. W.
Published: July 2010

Physical and chemical analyses of the soil samples chosen at random from over 90 fields from western Kansas during 1949 and 1950 were made to determine the rates of soil deterioration that are associated with the type of agriculture employed since the breaking of the virgin sod.

In land that has been utilized for grain production for 19 years about 9 inches of topsoil, constituting all of the A horizon, has been removed, mainly by wind erosion. This land is now much less productive and contains substantially less organic matter and less undecomposed crop residues than the newly broken land. Due to lower amounts of crop residue this “old” cultivated land is more exposed to erosion by wind and water. The soil itself, however, is more resistant to erosion now than when it was first brought under cultivation, due to the presence at the surface of the finer textured and more structurally developed soil of the original B horizon. When the protective influence of crop residues was discounted, the old cultivated land was found to be less than half as erodible as land broken out of virgin sod between 1946 and 1948. With crop failures such as occur on all types of land in dry years, the recently broken land would apparently become most vulnerable to erosion by wind.
Flame Photometric Determination of Exchangeable Magnesium in Soils
Authors: Rich C. I.
Published: July 2010

The Beckman flame spectrophotometer was studied to determine its application to the determination of magnesium in soil extracts. A high flame temperature and a narrow slit width increased the intensity of Mg (2852 Å) relative to the flame background. Centrifuging satisfactorily cleared extracts and prevented most clogging of the atomizer. Fe, Ca, and Na caused significant interference at the Mg band head of 3708 Å particularly with Mg concentrations below 2.00 ME/100 ml. At the 2852 Å line, Ca in concentrations greater than 8 ME Mg/100 ml depressed the Mg intensity; Al or PO4 in concentrations greater than 100 ppm Al or P slightly depressed the Mg intensity, whereas Na in concentrations greater than 10 ME/100 ml increased the intensity. Other elements tested (K, Mn, Fe, S, and Si) at 2852 Å had no apparent effect within concentration ranges usually found in ammonium acetate (1N) and 0.05N HCl soil extracts. Twenty‐four different soils of Virginia were analyzed for exchangeable magnesium by the photometric method, and results did not differ significantly (5% level) from the chemical method. The average recovery of Mg added to 0.05N HCl extracts was 103% and the standard deviation was 5.3%. The most favorable instrumental conditions found were: wave length, 2852 Å; slit width, 0.15 mm; propane pressure, 2.0 cm toluene; oxygen pressure, 75 inches H2O; air pressure, 18 pounds per square inch; sensitivity control, about one turn from the counterclockwise limit. The intensity scale was set on 100 when a solution containing 2.0 ME Mg per 100 ml was atomized and the milliammeter needle brought to zero with the sensitivity control.
The Effect of Humus on Cationic Interactions in a Beidellite Clay
Authors: McLean E. O.
Published: July 2010

Previous studies of cationic interactions have been made for the most part using relatively pure clay minerals. This has been a logical place to start, but to be of maximum practical benefit in solving agronomic problems sooner or later the resulting principles must be projected back to the natural soils. Too little is known about the relationship between ionic activities in plant media and nutrient uptake. But certainly one would not expect close correlation between these activities in pure clay and nutrient uptake from a soil high in this particular clay mineral unless there were no other substances present which possess exchange properties capable of interfering with activities and interactions caused by the clay mineral. In this connection it is obvious that the effect of humus on the cationic activities and their inter‐relationships is of utmost importance.

As a follow‐up to a similar study made previously with relatively pure beidellite clay, the present study has dealt with mixtures of 10 parts of the same clay to 1 part of crude humic acid. The activities of K, Na, and Ca in homoionic and in biionic systems were determined using the clay membrane electrode technique.

The results obtained are summarized as follows:

The exchange capacity of the clay‐humic acid systems was only 73% of that of the sum of the component parts.

Since the base saturations of the biionic systems were made up on the basis of the sum of the exchange capacities, the actual exchange capacities were exceeded somewhat.

This relatively higher base saturation in the clay‐humus systems resulted in higher activities of the cations in all cases than in the clay alone.

In spite of the higher activities in the clay‐humic acid systems the interactions of the cations were very similar to those in the clay alone.

If the clay‐humic acid systems studied can be considered as somewhat analogous to the situation in the field, this relatively small interference by the humic acid may possibly indicate that information gotten from similar studies with pure clay could be projected with some degree of assurance to a whole soil which contains a predominance of that particular clay mineral.

Evidence is presented in support of the contention that the loss in cation exchange capacity as a result of interaction of the component materials was due to a loss of exchange capacity by the humic acid rather than the obstruction of exchange spots on the clay.
Some Theoretical Aspects of the Flow of Water in Unsaturated Soils
Authors: Klute A.
Published: July 2010

The validity of Darcy's law in unsaturated media and the assumptions made in its use are discussed. The relationship of the permeability coefficient in Darcy's law to various soil parameters is briefly considered, the total soil moisture potential is defined, and its components discussed. By use of the equation of continuity and Darcy's law, an equation of flow is derived, and the general problem of obtaining solutions of this equation is outlined. The special mathematical difficulties encountered when the permeability is considered as a function of the moisture content or the capillary potential are also indicated. A numerical solution of the flow equation for a semi‐infinite system is given, using a functional relationship between the permeability and the moisture content, and the phenomenon of a wetting front is shown to be indicated.
The Prevalence of Strains of Rhizobium phaseoli in Some Midwestern Soils
Authors: Burton J. C. , Allen O. N. , Berger K. C.
Published: July 2010

This study was aimed to ascertain (a) the natural occurrence of R. phaseoli in certain soils, (b) whether any relationships existed between types of nodulation and efficiencies of the strains, and (c) homogeneity of reactions among strains isolated from the same nodule.

Variations among the strains in cultural and fermentative characteristics were marked, yet, on the whole, the strains isolated from the same nodules showed more uniformity in litmus milk reactions and ability to utilize the same carbohydrates than did those obtained from different nodules.

From a practical point of view bean rhizobia were not abundant in any of the soils tested. Rhizobia isolated from different nodules on the same plant varied widely in efficiency. Of the 85 strains isolated from nodules formed on plants grown in soil‐vermiculite mixtures, only 12 were highly effective. Differences in plant growth response to strains isolated from suspensions of the same nodule were insignificant.
Chromatographic Separations of Inositol Phosphorus Compounds
Authors: Smith Donald H. , Clark Francis E.
Published: July 2010

A chromatographic technique for the separation of sodium phytate and its enzymatically produced derivatives is described. From a mixture of sodium phytate and derivatives, nine organic phosphorus compounds were separated in sufficient quantities to permit determination of their inositol/phosphorus ratios. Phosphorus was determined colorimetrically following perchloric acid digestion, and inositol was determined by means of a biological assay. The determinations were replicated sufficiently that the number of phosphorus atoms per molecule of inositol was considered to have been determined to within one atom of the true value in all cases. The identity of the nine separated compounds was tentatively established.
Effects of Legumes in Different Cropping Systems on Yield of Corn
Authors: Reynolds E. B. , Norris M. J.
Published: July 2010

There were no significant differences in the yields of corn in 1950 at College Station where corn followed cotton which was preceded immediately by hairy vetch, Willamette vetch, Austrian Winter peas, Dixie Wonder peas, and Singletary peas plowed under for soil improvement. The application of 60 pounds of nitrogen per acre to the corn, however, produced a highly significant increase in the yield of corn.

Of the four legumes and six cropping systems included in the work at Denton, only Hubam and Madrid sweetclovers produced significant increases in the yield of corn in 1950. Corn after Hubam sweetclover for green manure produced only 2 bushels per acre more than corn following Hubam sweetclover for seed. Austrian Winter peas and Dixie Wonder peas did not increase the yield of corn, probably because they made very little growth.
Effect of Fumigation on Soil Aggregation
Authors: Martin J. P. , Aldrich D. G.
Published: July 2010

A study was made of the effects of several soil fumigants in moderate and high dosages and of steam sterilization on the aggregation of the <50 µ particles of five soils. The fumigants were injected into dry soil in large screw cap bottles, water sufficient to bring the moisture content of the soil to 50% of capacity was immediately added, and the lids tightly secured. After 3 days the soil was air‐dried, placed in 16‐ounce jars in 420‐gram portions, adjusted to 50% moisture capacity, and incubated. Microbial counts and aggregate analyses were made after 0‐, 10‐, 20‐, 50‐, 100‐, and 250‐day incubation periods.

The fumigation treatments markedly affected the microbial population of the soils but had little or no effect on aggregation. In high dosages, D‐D, chloropicrin, and ethylene dibromide slightly increased the aggregation of one soil, namely, Yolo loam at the 0‐day incubation period only. Steam sterilization increased the aggregation of Yolo loam, an unnamed mountain soil, and Hanford sandy loam. In the latter two soils, the effect was not significant after the 0‐day incubation period. Increased aggregation was associated with decreased wettability of the soil.

The study indicates that aggregation is influenced more by products of microbial activity during the decomposition of organic waste material than by numbers of microorganisms. Fumigation apparently does not provide sufficient energy material in the form of dead microbial cells and adsorbed fumigant to change the aggregation status of a normal soil significantly, or destruction of organic cementing materials by increased microbial activity counteracts any aggregating effect.
Field and Laboratory Studies of Nitrite Accumulation in Soils
Authors: Chapman H. D. , Liebig George F.
Published: July 2010

A field and laboratory study of nitrite accumulation under arable soil conditions was carried out using a considerable number of nitrogen fertilizers applied at various seasons of the year. The results show that nitrite will accumulate under neutral or alkaline soil conditions provided the rate of fertilization is heavy enough to produce a considerable concentration of the ammonium ion. Under field conditions, especially where the soils are not warm enough for rapid biological activity, the nitrite produced may persist for several months. For example, nitrite accumulating from urea applied in January (43 ppm N as NO2) persisted into May (31 ppm N). Amounts of nitrite up to 90 ppm N were produced under favorable conditions. More nitrite was produced from urea than any other nitrogen fertilizer. This is considered due to the high ammonia and pH conditions resulting from application of this material. In none of the field studies was there any evidence of nitrite accumulation from denitrification though occasionally heavy fertilization with nitrate fertilizer supplemented with straw was immediately followed by heavy rains or irrigation. From these studies, it appears that wherever two conditions occur, namely, fairly high ammonium concentrations and neutral or alkaline soil conditions, more or less nitrite accumulation may be expected.
A Key for Evaluating Soil Permeability by Means of Certain Field Clues
Authors: O'Neal Alfred M.
Published: July 2010

Field clues to soil permeability were investigated at 182 locations from 1947 through 1951. Estimates of permeability were made in the field without prior knowledge of measured percolation rates. Then the estimated permeability class was compared with the measured rate. In case of discrepancy, the profile was re‐examined to see if any signfiicant clues had been overlooked. It was found that permeability could be estimated, with fair precision, from information obtained in the field, in terms of seven classes that are defined in terms of saturated percolation rates.

The first step is determination of the type of structure. Then the class of permeability is estimated from four principal clues and one or more of eight secondary clues. Types of structure and structureless conditions found significant are fragmental, platy, nuciform, cubical blocky, prismatic, single grain, and massive. Principal clues are relative dimensions, horizontally and vertically, of structural aggregates; amount and direction of over‐lap of the aggregates; number of visible pores; and texture. Important secondary clues are compaction, direction of natural breakage, silt content, cementation, type of clay minerals, character of coatings on aggregates, degree of mottling and certain features of climate. None of these clues, when taken singly, is a reliable indicator of permeability, but each must be considered with reference to the others.
Effect of Increasing Fertilizer Concentration on Exchangeable Cation Status of Soils
Authors: Bear F. E. , Prince A. L. , Toth S. J.
Published: July 2010

In a 10‐year experiment, comparisons were made of the effects of fertilizers of 1‐2‐2 N, P2O5, and K2O ratios, applied at the rate of 1 ton of 4‐8‐8 an acre annually, or its equivalent in higher grades up to and including the 12‐24‐24, on the exchangeable cation status of two soils. The most significant general effects of all these grades were the lowering of pH values, increase in exchangeable H, reduction in exchangeable Ca and Mg, and increase in exchangeable K. There was little in the evidence to indicate any bad effects that could not readily be overcome by the use of Mg‐containing liming materials as correctives.
Readily Available Water in Forest Soils
Authors: Gaiser R. N.
Published: July 2010

Year‐long records of soil moisture are reported for three forest soils of southeastern Ohio. Sustained maximum and minimum soil moisture levels are in close agreement with the moisture equivalent and permanent‐wilting percentage as determined in the laboratory and greenhouse. Data on the relationship of readily available water to soil texture are presented for soils of the Muskingum‐Wellston‐Zanesville association.

Moisture losses from the soil through transpiration and evaporation during the 1951 growing season amounted to 13, 12, and 23 inches for the soils examined. The greatest loss was from Zaleski loam on a lower slope, and the smaller losses were from Wellston silt loam and Muskingum loam found on a ridge and upper slope. It is believed that moisture losses through evaporation from the soil proper are small and that the losses reported closely approximate the amount of moisture extracted for transpiration. The growth rate of white oak (Quercus alba L.) is considerably more rapid on the Zaleski loam than on the other soils.

Because utilization of water is complete on the moist sites, it appears that the oak forests are capable of transpiring more water than is ordinarily available. In years of average precipitation, as much as 25 inches of water might be used in transpiration from trees and evaporation from all soil surfaces in the forest during the growing season. The remaining 15 inches of the average 40‐inch rainfall may be accounted for by evaporation, runoff, and deep seepage during the rest of the year.
Ethylene Glycol Retention by Soils as a Measure of Surface Area and Interlayer Swelling
Authors: Bower C. A. , Gschwend F. B.
Published: July 2010

The ethylene glycol‐retention method proposed by Dyal and Hendricks for determining interlayer swelling and the surface areas of clays has been modified for use on soils. The modified procedure is described. Data are presented showing that values for external surface area obtained by the ethylene glycol‐retention method agree satisfactorily with those obtained by the Brunauer‐Emmett‐Teller gas‐adsorption method. The effects of various exchangeable cations, organic matter and soluble salts upon ethylene glycol retention were studied. The nature of the exchangeable cation had no significant influence upon values obtained for external retention by soils. Total retention by calcium‐ and hydrogen‐saturated samples tended to be higher than that by sodium‐ and magnesium‐saturated samples. The lowest values for total retention were obtained on potassium‐ and ammonium‐saturated samples. The presence of organic matter increased values obtained for total retention. The apparent surface area of the organic matter in four soils varied from 558 to 803 sq. meters per gm. When calculated on a salt‐free basis, values for retention are not significantly affected by the presence of soluble salts.
Status Report on Soil Conditioning Chemicals. I.
Authors: Martin W. P.
Published: July 2010

Because of the short time the synthetic soil conditioners have been available for test, it is not possible to draw other than tentative conclusions. However, it appears fairly evident that they can effect marked improvement in the physical state of soils if properly applied. Rates of application of the order of 0.05% are such that at current prices the usefulness of these products in agriculture is likely to be limited to surface application with high value crops or for special purposes. It is not likely that they will constitute a replacement for, but will be an important supplement to sound agricultural practices. A sound body of information on which to base recommended procedures for the great variety of crops and soils found in the country at large is gradually accumulating because of the widespread interest of agronomists and others in this latest development from the field of chemistry.
Electrophoresis of Clays by the Schlieren Moving Boundary Procedure
Authors: Beavers A. H. , Larson B. L.
Published: July 2010

Electrophoresis, as analyzed by the schlieren moving boundary system, has been used as a method for the study of the clay minerals. By the use of suitable buffers and standardized procedure for preparation, clay suspensions of sufficient concentration but of low opacity were prepared. Sodium veronal was found to be an effective dispersing agent for the hydrous mica‐like clays (Putnam and Cisne) and versenate and phosphate for the bentonite (montmorillonite) clays. It was found necessary to use the hydrogen clays dispersed in the appropriate buffer. Repeated attempts using the sodium clays gave suspensions unsuitable for electrophoretic analysis.

The Putnam and Cisne subsoil clays were found to be either electrophoretically homogeneous or almost so in each of several buffer systems used, whereas the bentonite clays were found to be very heterogeneous. Artificial mixtures of the subsoil clays and the bentonite clays indicated that they could be separated electrophoretically since the subsoil clays possess mobilities slower than any of the bentonite components.

Ultracentrifugal analysis of the Putnam clay indicated the presence of two major components. Since these did not show up on the electrophoretic patterns, it would seem to indicate that the electrophoretic entities are not due to differences in particle size.

The pH and buffer concentrations were found not to materially affect the mobility of the clay systems.

It would appear that further study of the electrophoretic properties of clays by the schlieren moving boundary system is warranted.
The Effect of Spring Nitrogen Fertilization on Plant Characteristics of Winter Wheat
Authors: Hobbs J. A.
Published: July 2010

A study designed to determine the effect of nitrogen top‐dressing on plant characteristics, yield, and protein content of winter wheat was undertaken at Kansas State College in the spring of 1944. Nitrogen fertilizer was applied prior to March 15 to strips of winter wheat in the permanent fertility plots. Yield, protein content, and other data were collected from the top‐dressed and the untreated areas.

The results indicated that spring applications of nitrogenous fertilizers increased the yield and also increased the protein content. The increases in yield were especially prominent on the plots which were adequately supplied with phosphate. Analysis of several plant growth characteristics indicated that much of this increase could be accounted for by increased tillering and by increased number of kernels per head. Other plant characteristics, such as kernel weight, had little, if any, effect on the increased wheat yields.
Some Observed Calcium Deficiencies in Corn under Field Conditions
Authors: Melsted S. W.
Published: July 2010

Typical calcium deficiencies in corn obtained under field conditions are reported. The plants showing the typical deficiency symptoms contained less than 0.2% of calcium in the plant as a whole. The pH of the soils was less than 4.5, and the exchangeable calcium was less than 2 milliequivalents per 100 grams of soil. The deficiency was brought about by the addition of large amounts of nitrogen, phosphorus, and potash fertilizers to acid soils without correcting the acidity.
Influence of Forest Cover on the State of the Ground Water Table
Authors: Wilde S. A. , Steinbrenner E. C. , Pierce R. S. , Dosen R. C. , Pronin D. T.
Published: July 2010

The state of ground water level was determined in forested and cutover soils of central and northern Wisconsin by observations of open wells during the frost‐free periods. In nonpodzolic, coarse, sandy soils, ground water possesses considerable mobility, and forest cover effected only a slight lowering of the water level, not exceeding 9 inches. The influence of forest cover was most pronounced in the middle of the growing season; from October to May the water table occupied nearly a horizontal position. In strongly podzolized, morainic soils, however, clear cutting of aspen stands produced an average rise of 14 inches, and converted a reasonably well‐drained soil into a semiswamp. In the rainy spring and summer of 1952, this alteration of the ground water table was accompanied by increased run‐off, erosion, and damages to roads.
Effect of Sample Drying on the Determination of the Water‐stability of Soils
Authors: Slater C. S.
Published: July 2010

Water‐stability analyses, to determine structural quality in soils, reflect field conditions only to the extent that the soil samples on which they are based remain unmodified (or are modified uniformly) by the treatment received between the times of sampling and analysis. Air drying of the sample is an accepted procedure. This paper reports the effects of air drying samples at different temperatures as indicated by the results of water‐stability analyses. It is concluded that if the samples are air dried at rates and temperatures that are characteristic of ordinary variations in laboratory conditions, the variations of stability so induced do not modify greatly the relative levels of stability represented by the samples. However, the induced variation was greater, over a temperature range of from 40°F to 180°F, than that between duplicate analyses.
Pressure Distribution in Layered Soils during Continuous Water Flow
Authors: Day Paul R. , Luthin James N.
Published: July 2010

The occurrence of a pressure deficiency (“tension”) in the liquid phase of flooded, freely drained soils has been observed in texturally stratified columns in the laboratory. This phenomenon has been explained in the following way on the basis of Darcy's law: If water flows downward through a soil layer at a rate which exceeds its hydraulic conductivity value, the loss of head by friction will exceed the energy supplied by gravity, and a pressure drop will occur along the path of flow.

A moderately permeable surface soil over a highly permeable substratum presents an excellent opportunity for the development of tension in the soil during flooding operations. The practical implications of this fact are discussed with reference to water spreading investigations.
Cation Exchange in Soils Through the Moisture Range, Saturation to the Wilting Percentage
Authors: Brown D. A.
Published: July 2010

Data are reported to show the effect of soil moisture upon cation exchange in soils through the moisture range, saturation to wilting percentage, for seven soil series, including Lakeland, Ruston, Richland, Crowley, Sharkey, Houston, and Gila. Cation exchange resin membranes of known exchange capacity were saturated with the hydrogen ion and buried in 100‐gram aliquots of each of the above soil series. These aliquots of soil were moistened to cover the range, saturation to the wilting percentage, in a systematic manner. The membranes were allowed to remain in the soil for 96 hours, then removed, and the amounts of Ca, Mg, Na, and K exchanged to them from the soil measured quantitatively.

The amounts of cations exchanged increased sharply as the soil moisture increased. The increase in cation exchange at saturation when based upon that exchanged at the moisture equivalent was 7 fold for Lakeland, 5 for Ruston, 2 for Richland, 3 for Crowley, but only a 0.2‐fold increase for Sharkey, Houston, and Gila series. The percentage decrease in cation exchange at the wilting percentage, when based upon the exchange at the moisture equivalent was 50, 65, 85, and 72 for Lakeland, Ruston, Richland, and Crowley, respectively, but only 14, 19, and 25% for Sharkey, Houston, and Gila, respectively. The suite of exchanged cations were significantly altered with increases in moisture.

The percentage of Ca and Mg increased in the suite of cations, while that of K and Na decreased correspondingly as the soil moisture increased. The Ca:K ratio increased from 60 to 266 over the moisture range, wilting percentage to saturation, for the Houston series, 10 to 60 for the Richland series, but only 7 to 10 for the Lakeland series. The cation exchange‐moisture relationships are explained on the basis of the relative abundance and continuity of the water films within the pore system of the soil that may effectively serve as a medium for the diffusion of cations through the soil.
Zinc Status of Some Illinois Soils as Estimated by an Aspergillus Niger Method
Authors: Tucker T. C. , Kurtz L. T. , Lynch D. L.
Published: July 2010

An extremely sensitive semiquantitative method for bio‐assay of zinc in soils with Aspergillus niger is described. Data at present do not permit the validation of the assay as an index of response by higher plants on soils of Illinois. Present investigations are being conducted to locate soils that will respond to zinc fertilization. It is hoped that these studies will show a positive relationship between the bio‐assay of zinc in the soil and crop response, and perhaps lead to a chemical method which will appropriately measure the available form of zinc in soils. The method as outlined was used for acid soils and is not applicable to alkaline or calcareous soils.

Although the procedure is relatively simple, extreme care must he exercised in order to prevent contamination with zinc from reagents and equipment. Reagent grade chemicals were used and purification of water and sucrose was effected by an ion‐exchange resin. An acid cleaning solution was the most effective method tried for removing traces of zinc from equipment. Sterilization of the soil to be assayed is not recommended.

The growth response of Aspergillus niger was related to known increments of zinc in 50‐ml nutrient solution in 500‐ml Erlenmeyer flasks. This relationship was used to evaluate the zinc status of soils. Florida soils known to respond to zinc fertilization ranged from 0.6 to 2.88 ppm zinc and Illinois soils ranged from 1.6 to 21.5 ppm zinc, according to the bio‐assay. It is conceivable that a few Illinois soils may respond to zinc fertilization or are at least approaching a critical level.
Some Relationships between the Classification of Rocks by Geologists and the Classification of Soils by Soil Scientists
Authors: Whiteside E. P.
Published: July 2010

A unified philosophy is presented of some of the basic relationships between the classification of rocks by geologists and the study of soils for students and teachers in these fields. These include the differentiation of rocks and soils, the definition of parent rock, and a suggested approach to the classification of parent rocks.

The descriptive classification of igneous rocks by geologists is shown to be very useful to soil scientists, while their classification of sedimentary rocks has lagged behind the fundamental needs of pedologists. A summary of some of the basic contributions by geologists and soil scientists in this field is presented. It is hoped that the challenge of the past achievements and the current needs will stimulate further critical studies in these areas of mutual interest to geologists and pedologists.
Soil Erosion on Logging Roads
Authors: Trimble George R. , Weitzman Sidney
Published: July 2010

In rugged mountainous country, skid roads used in logging operations cause serious erosion. To determine the important factors in skid‐road erosion, and to find ways to reduce this erosion, sample skid roads were studied before, during, and after experimental logging operations on the Fernow Experimental Forest in West Virginia.

Erosion was related to grade, length of slope, intensity of use, soil, vegetation, and climatic factors. Degree of erosion was determined for different skid‐road conditions.

Measures for reducing erosion are recommended for use in locating, constructing, using, and maintaining skid roads. Drainage measures such as diversion ditches and water bars are essential. Spacings for water bars are recommended for different grades.
The Application of the Gouy Theory to Soil‐Water Systems
Authors: Bolt G. H. , Peech Michael
Published: July 2010

This paper shows how the Gouy theory may be used to describe the properties of soil and clay suspensions. The volume charge density and the potential distribution in a single layer may be calculated for widely different clay suspensions if the surface density of charge and the concentration of free electrolyte are known. The interaction between two diffuse double layers of adjacent particles leads to a differential equation describing the volume charge and potential distribution that can be solved only for suspensions containing symmetric electrolytes. Sufficiently accurate approximations of the charge and potential distribution may be made, however, for suspensions containing asymmetric electrolytes. Due consideration must be given to the specific adsorption potential of ions in the Stern layer. By means of the Gouy theory it is possible to calculate such measurable quantities as negative adsorption, osmotic pressure, and membrane potential. A comparison of the applicability of the Donnan and the Gouy theories shows that the Gouy theory is superior in describing and predicting the properties of deflocculated clay suspensions. Indeed, the application of the Donnan theory to such systems leads to serious errors.
The Significance of Potentiometric Measurements Involving Liquid Junction in Clay and Soil Suspensions
Authors: Peech Michael , Olsen R. A. , Bolt G. H.
Published: July 2010

A critical study has been made of the behavior of the liquid junction between the saturated KCl and the clay or soil suspension in attempt to evaluate the sign and the magnitude of the junction potential in measurements of membrane potentials and ion activities. In deflocculated suspensions of clay saturated with monovalent cations, the saturated KCl in the salt bridge short‐circuits the potential drop across the diffuse double layer and thus exaggerates the magnitude of the membrane potential or the ion activity of the clay suspension predicted by the Gouy theory. In suspensions of Ca‐clay and most soils, however, the effect of short‐circuiting the small potential drop across the diffuse double layer is more than offset by the diffusion potential due to CaCl2 that is formed ahead of the KCl diffusion front. The sign of this diffusion potential is such as to decrease the magnitude of the membrane potential or the ion activity of the clay suspension. Comparison of the observed osmotic pressure of clay suspensions with that calculated according to the Gouy and the Donnan theories fully confirmed the conclusions reached from the potentiometric data concerning the sign and magnitude of the liquid junction potential.
Increased Color Stability in the Determination of Magnesium
Authors: Yien C. H. , Chesnin Leon
Published: July 2010

The method of Drosdoff and Nearpass was modified for the determination of magnesium in plant and soil extracts. One method is proposed for the analysis of ammonium acetate extracts of soils, and another method is proposed for the analysis of plant materials and water extracts of soils. These methods, which determine the magnesium content colorimetrically with the use of thiazole yellow, introduce the use of sodium bisulfite to stabilize the color obtained. Polyvinyl alcohol is used to obtain suspension stability. A procedure for the determination of magnesium with titan yellow is also presented.

A number of soil and plant samples were analyzed by the A.O.A.C. method, the proposed methods, and the method of Drosdoff and Nearpass. Values obtained for the magnesium content of the soils and plants indicate greater accuracy and reproducibility of duplicate determinations by the modified procedures than by the Drosdoff‐Nearpass method. The modified methods are more sensitive to changes in magnesium concentration than is the Drosdoff‐Nearpass method. Color stability of 24 hours have been obtained with the titan yellow procedure and the method used for plant analysis, and one hour of color stability has been obtained with the method used for determining exchangeable magnesium. The proposed procedures are rapid, accurate and reproducible. Stability of color and suspension, and facility of the methods adapt these procedures to mass routine analysis of samples for magnesium.
Correlation of Soil Tests for Available Phosphorus and Potassium with Crop Yield Responses to Fertilization
Authors: Long O. H. , Seatz L. F.
Published: July 2010

Separate yield responses to applied P and K were correlated with soil tests for these elements on 72 experiments with corn, 18 with cotton, 35 with small grains, 28 with legume hays and 11 with permanent pastures. Sodium perchlorate in N/10 perchloric acid was the extracting agent.

Results are presented in graphic form showing soil‐test values for P and K plotted against crop yields obtained without P or K expressed as percent of yields where phosphate or potash was applied.

Two methods of approach are used in showing the degree of correlation. One method is concerned with “prediction accuracy” at only the lower values of soil P or K. The other method is concerned with the regression curves and correlation coefficients for the experiments as a whole.

Responses of corn to phosphorus fertilization on loess‐derived soils correlated least satisfactorily with the soil test where a predicted yield response was obtained in only 17% of the tests. Permanent pastures showed the best correlation; all experiments were on soils low in phosphate and responded to applications of P. The prediction accuracies obtained with other crops were as follows: corn, on limestone‐derived soils, 64%; cotton, 54%; small grains, 70%; and legume hays, 63%.

Responses of cotton to potassium fertilization indicated the best correlation with the soil test, the prediction accuracy being 60%. The prediction accuracies obtained with the other crops were: corn, 44%; small grains, 47%; legume hays, 33%; and permanent pastures, 57%.

The correlation coefficient (r) was not significant with respect to P on any crop; it was significant with respect to K only on corn.
Coordinated Soil‐Plant Analysis I. Nutrient Cations
Authors: DeLong W. A. , MacKay D. C. , Steppler H. A.
Published: July 2010

Analytical data for composite samples of soil and of corn leaf tissue collected during two years from four soil types, all soils receiving very closely similar fertility and management treatments, are presented. The area from which the samples were taken is operated as a seed production unit. The sequence of crops is cereal grain, corn, cereal grain, cereal grain, clover and timothy. Commercial fertilizer, 4‐12‐6, is used and crop residues are left on the land. Exchangeable calcium, magnesium and potassium, and exchange capacity were determined, and tests for free carbonates were made on the soil samples. Total calcium, magnesium and potassium values were determined for the leaf samples. All cation determinations were made by flame photometry. The range in exchangeable cation values for the four soils, except for the carbonate phase of one soil, was relatively small, about 30 percent, yet these soils under uniform management produced corn plants the leaf tissue of which differed significantly in content of potassium and of magnesium. The amounts of these elements in the leaf were modified strongly by the presence of free carbonate in the soil, and by seasonal and/or site influences. The exchangeable calcium: exchangeable potassium ratio in terms of milli‐equivalents per 100 grams soil proved to be a much better index of the potassium content of the leaf than did the exchangeable potassium value alone, the latter expressed either as milli‐equivalents or as percent saturation of the soil colloid. The calcium: potassium ratio showed a highly significant negative correlation with the amount of potassium in the leaf in both years. The exchangeable potassium of the soil showed a significant negative correlation with the magnesium content of the leaf in one year but not in the other. The potassium content of the leaf showed a significant negative correlation with the magnesium content of the leaf in both years. Further, this correlation was more significant than that of the potassium of the soil with the magnesium of the leaf in both years.
A Comparison of Five Methods for Expressing Aggregation Data
Authors: Schaller F. W. , Stockinger K. R.
Published: July 2010

Five ways of expressing aggregation data have been in common use in recent years. These are: percent aggregates greater than 2 mm, 1 mm and 0.25 mm, and geometric mean and mean weight‐diameter. To determine the advantages or disadvantages of the several indices, aggregation results obtained by the Yoder method on several hundred soil samples from three locations in Iowa have been compared. Correlation coefficients were obtained between the mean weight‐diameter and the percent of aggregates > 2 mm, > 1 mm, and > 0.25 mm, and also the geometric mean. The geometric mean was also correlated with the three size separates. The results indicate that a single size fraction such as the > 2 mm or > 1 mm can be satisfactorily used to express soil aggregation. This method of expression would be as reliable (to within the 1% level of significance) as that indicated by the two indices, mean weight‐diameter and geometric mean, which utilize all size fractions. However, it was shown that more replications are necessary for equal accuracy when only a single size fraction is used. If time is to be saved in making the laboratory determinations, it is suggested that a size fraction such as the > 2 mm or > 1 mm might be determined more quickly and with greater accuracy by developing a method using one or two sieves and a larger soil sample. The final selection of an index for expressing soil aggregation must be based on the ability of the index to correlate with crop response.
Moisture Available to Various Crops in Some New Jersey Soils
Authors: Corey A. T. , Blake G. R.
Published: July 2010

Moisture available to wheat, potatoes, tomatoes, and sweet corn was determined by combining moisture retaining characteristics of soils, and depths to which crops exploit the water reservoir. Soil types on which some or all of the crops were grown included Sassafras and Nixon loams, Penn silt loam, and Collington loamy sand.

Available water in a unit depth varied with soil type and with horizon in a given soil type.

Effective rooting depth of a crop was defined as the maximum depth to which soil continued to lose moisture after a prolonged period of rainless weather. Moisture samples determined gravimetrically were each referred to a standard of 100 cm. water tension to give relative wetness values. When depth vs. relative wetness was plotted, effective rooting depth was a clearly defined point below which insignificant quantities of water were obtained by plants.

Effective rooting depth of sweet corn varied with soil type from 11 to 35 inches. It also varied on a given soil with kind and age of crop.

When differences in rooting depth were combined with moisture in unit depth, tomatoes had about four times as much water at their disposal in Sassafras loam as in Nixon loam. Wheat had less than half as much as tomatoes when both were growing on Sassafras loam.
Pressure Distribution in Soil Columns Draining into the Atmosphere
Authors: Luthin James N. , Miller Robert D.
Published: July 2010

Columns of soil 122 cms long were first wetted with water and then allowed to drain into the atmosphere. During the drainage period, measurements were made of the pressure distribution in the soil columns and of the rate at which water drained out of the columns into the atmosphere. At the conclusion of the experiment, the soil columns were sectioned and the moisture distribution measured.

The experimental results emphasize the importance in drainage of the tension required to produce entry of air into the soil surface. The difficulty experienced in the drainage of tight clay soils may be due more to the high tension required to produce entry of air into the soil than to the low hydraulic conductivity of the soil.

Indirect evidence indicates that in the field, movement of water in the capillary fringe above the water table may be of considerable importance. This is especially true for the case of the falling water table. The use of Laplace's equation in the study of flow in the capillary fringe is discussed briefly.
Determination of Fixed Soil Potassium
Authors: Kolterman Delbert W. , Truog Emil
Published: July 2010

After making preliminary tests of methods proposed by other investigators for determining the fixed potassium of soils and also of several new approaches, the approach found most promising — heating at 500° C for two hours — was investigated in considerable detail. It was found that on heating ammonium saturated soils, illite, and bentonite in this manner, substantial release of nonexchangeable or fixed potassium could be effected without breakdown of primary potassium minerals. Not all of the fixed potassium can be released in one heating, the amount thus released representing an equilibrium point related to the amount which still remains fixed.

The procedure finally adopted consists in heating ammonium saturated soil at 500° C for two hours, then extraction of the potassium made exchangeable with ammonium acetate solution, and finally determination of the potassium in the solution by means of the flame photometer. This heating, extraction, and determination are repeated once, and from the amount of fixed potassium released during the second heating, the total amount of fixed potassium present may be calculated by use of a summation formula for a geometric progression. The method is simple and is adaptable to rapid analysis of large numbers of samples. On the basis of the results obtained with soils and minerals, it is believed that the method is reasonably specific for fixed potassium, and offers the possibility of being a practicable and reliable method.
Effectiveness and Recovery of Phosphorus and Potassium Fertilizers Topdressed on Meadows
Authors: Hanway John , Stanford George , Meldrum H. R.
Published: July 2010

A two‐year experiment was conducted in which phosphorus and potassium fertilizers were topdressed each year on an alfalfa‐timothy meadow. In 1950, rates of 0, 60, and 120 pounds per acre of P2O5 and K2O were applied alone and in all combinations. In 1951 each plot was split with a factorial of 0 and 60 pounds per acre of P2O5 and K2O. Determinations of yield, botanical composition and chemical composition of the hay were made. Soil analyses were made to determine depth distribution of available nutrients in the soil.

The soil was very low in “available” phosphorus and potassium and large increases were obtained from the fertilizer applications.

There was competition between the alfalfa and timothy for both phosphorus and potassium. Alfalfa was the dominant competitor for phosphorus while timothy offered the most competition for potassium.

Very efficient recovery of the topdressed phosphorus was indicated.

The apparent recovery of applied potassium was as high as 100% from several treatments. The chemical data indicate that even the maximum application of 180 pounds of K2O per acre in the two years was not sufficient for maximum yield on this very potassium deficient soil.

Soil tests at the end of the experiment indicate a considerable increase in “available” phosphorus in the surface layer from applications of 120 or more pounds per acre of P2O5. The residual effect of potassium applications could not be detected by soil tests.