bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effects of Exchangeable Calcium on the Retention and Fixation of Phosphorus by Clay Fractions of Soil
Authors: Ragland J. L. , Seay W. A.
Published: July 2010

Laboratory studies were made of the phosphorus retaining and fixing properties of four Kentucky soils. The soils studied were: Armour, Pembroke, and Memphis silt loams, and Loradale silty clay loam. All work was done with the clay fraction of the soils. The effect of percent calcium saturation of the clay, rate of phosphorus application, and initial saturating cation were studied. Retained phosphorus was considered to be that portion of the added phosphorus removed from a water solution by the clay separate. Fixed phosphorus was considered to be that portion of the retained phosphorus not recovered from the clay separate by extraction with 0.005N H2SO4. Radioactive phosphorus was used in the experiment. Phosphorus retention and fixation were determined by a solution counting technique.

With a rate of 100 parts of P2O5 per million parts of clay, phosphorus retention and fixation by the four initially acid saturated clay fractions increased as the percent calcium saturation of the clay was increased. No sizeable increase occurred until the clay separates were about 60% calcium saturated. When phosphorus was applied to Loradale clay separate at a rate of 800 or more parts of P2O5 per million parts of clay, fixation decreased with increasing percentages of calcium saturation. This would indicate that fixation studies should be carried out with rates of phosphorus application comparable with those used on field crops if laboratory results are to be extrapolated to field conditions.

Initially aluminum saturated clay separate retained much more of the added phosphorus but fixed no more of it than initially acid saturated clay separate.

Phosphorus fixation by clay separates with “natural” base saturation decreased with increasing pH, whereas fixation by initially acid saturated clay separate increased or remained unchanged with increasing pH. This may indicate that fixation studies made with initially acid saturated clay separates are not accurate indications of fixation as it occurs under natural soil conditions.
The Influence of Straw and Straw‐Fertilizer Composts on the Uptake of Fertilizer Phosphorus by Plants
Authors: Fuller W. H. , Nielsen D. R.
Published: July 2010

The application of solutions of inorganic phosphorus fertilizers to crop residues before the residues are tilled into the soil is now a widespread practice in the Southwest. This practice is centered around the hope that the fertilizer phosphorus will remain at a higher level of availability as a result of this procedure than if it were added directly to the soil. The hypothesis is that phosphorus fixed by microorganisms during the decomposition of the crop residue is only temporarily unavailable to plants. Phosphorus fixed by this method presumably would be made readily available to plants during the latter stages of decomposition of the residues in contrast to the irreversible fixation by the inorganic constituents of the soil.

Results with wheat straw and wheat straw composts containing tagged phosphorus indicate that a relatively greater amount of phosphorus is utilized by plants from compost than from noncompost material. The compost had lost 40 to 50% of its original weight as a result of decomposition before being added to the soil. On the other hand, results with phosphorus‐free extracted oat straw showed that the less decomposed material (oat straw plus KH2PO4) supplied more P to ryegrass growing on Mohave clay loam than the compost (oat straw composted with KH2PO4). However, the extracted oat straw composts did not decompose to an extent to exceed 20% before being added to the soil.

According to the data obtained, it must be concluded that there is no particular advantage of adding liquid phosphoric acid fertilizers directly to straw before incorporating them into calcareous soils over the practice of applying the fertilizer and straw residues independently.
Availability of Residual Phosphorus from Long‐Time Rock Phosphate and Superphosphate Applications to Groseclose Silt Loam
Authors: Moschler W. W. , Krebs R. D. , Obenshain S. S.
Published: July 2010

The availability of residual phosphorus from long‐time superphosphate applications to Groseclose silt loam exceeded that of rock phosphate. Based on A values, residual phosphorus from superphosphate was approximately four times as available as that from rock phosphate.

Data on total, Truog, and NaHCO3‐soluble phosphorus showed that: (1) more of the superphosphate had reacted with the soil than had rock phosphate; (2) more of the phosphorus applied as superphosphate had accumulated in the silt and clay factions of the soil and, based on solubility in NaHCO3, was relatively available; and (3) more of the phosphorus applied as rock phosphate had accumulated in the sand fraction of the soil and was relatively unavailable, as judged by solubility in NaHCO3.

Apparently, some of the rock phosphate had not reacted with the soil and was still in its original molecular combination. X‐ray analysis revealed the presence of apatite or a mineral similar to apatite in the sand fraction of soil that had received rock phosphate. The mineral, which gave pronounced reflections at the same values obtained from rock phosphate fertilizer, was not found in soil receiving superphosphate.

Approximately three‐quarters of the phosphorus applied over a 40‐year period from either source was present in the soil as residual phosphorus. This quantity nearly doubled the total phosphorus content of the soil. Crop yields on plots receiving the two fertilizers have been equal except for the first few years when superphosphate produced higher yields.
A Biological Slope‐Ratio Method for Evaluating Nutrient Availability in Soils
Authors: McCants C. B. , Black C. A.
Published: July 2010

The slope‐ratio method employed in biological assay was investigated as a means of evaluating the relative availability of a nutrient in different soils. This type of assay is used when the biological response increases linearly with the dose of the active ingredient. Under certain conditions the relative concentration of the active ingredient in two or more sources tested is equal to the ratio of the slopes of the lines representing the responses. To obtain linear responses, conditions of strong nutrient deficiency were imposed by growing the test plants in sand cultures to which increasing quantities of soil were added. Nutrients other than the one being evaluated were supplied in ample amount. In an experiment with nitrogen the results of three different types of experimental tests indicated that the ratio of the slopes of the lines representing the response functions provided a satisfactory estimate of the ratio of the availabilities. In an experiment with phosphorus, the tests indicated that for the various soils in general the ratio of the slopes was not a valid estimate of the relative phosphorus availabilities. In two instances in which there was no evidence that the slope ratios did not indicate the relative availabilities, the ratios of the availability of fertilizer phosphorus in the presence of soil to that in the absence of soil were found to be 0.2 and 0.5. These results demonstrate the invalidity of methods in which inferences about availabilities of soil phosphorus are based on the assumption that fertilizer phosphorus has the same availability in all soils.
Manganese Toxicity and Soil Acidity in Relation to Crinkle Leaf of Cotton
Authors: Adams Fred , Wear John I.
Published: July 2010

A Kalmia fine sandy loam having a pH of 4.5 on which crinkle leaf of cotton occurred in the field was studied in the laboratory and greenhouse.

An application of CaCO3 and Na2CO3 to the soil prevented the occurrence of crinkle leaf, whereas the addition of a neutral calcium salt did not prevent the abnormality. Water‐soluble manganese in the soil was greatly reduced by CaCO3 or Na2CO3; however, these salts had little effect on the amount of exchangeable or reducible manganese. CaCl2 had little or no effect on the abundance of any form of soil manganese.

A technique was used that maintained high acidity of the soil solution while controlling the amount of manganese and aluminum in solution. By this technique, the symptoms of crinkle leaf were shown to be the result of a high level of manganese in the soil solution and not because of some other factor associated with high soil acidity.

Crinkle leaf of cotton can be expected as sufficient acidity develops in those soils that have a high potential supplying power of soluble manganese. The necessary preventive measure for crinkle leaf in the field is an adequate liming program.
Preliminary Studies of Molybdenum in Illinois Soils
Authors: Haley L. E. , Melsted S. W.
Published: July 2010

Various methods of extracting molybdenum from soils have been examined and results compared with the total soil molybdenum and plant composition. The reagents employed for extracting molybdenum were 0.1 N NaOH, 0.275 M oxalate, 0.1 N HCl + 0.03 N NH4F, and 0.03 N NH4F. Total molybdenum was determined by a modification of the method of Grigg and Perrin. Plant analyses were made by the method of Johnson and Arkley.

Total molybdenum in the soils studied ranged from 1.90 ppm. to 3.20 ppm. whereas the plant samples ranged from 0.27 ppm. to 10.65 ppm. molybdenum. The following sequence of extraction of molybdenum was observed: 0.1 N NaOH > Tamm's acid ammonium oxalate > 0.03 N NH4F > 0.1 N HCl + 0.03 N NH4F. The only forms of soil molybdenum that gave statistically significant correlations with plant composition were the forms extracted by sodium hydroxide and acid ammonium oxalate.
Design of Plots Conforming to the Land for Evaluating Moisture Conservation Practices
Authors: Daniel Harley A. , Cox Maurice B. , Tucker Billy B. , Viets Frank G.
Published: July 2010

A system of plots designed to conform to the land was in operation on the Wheatland Conservation Experiment Station, Cherokee, Oklahoma, from 1942 through 1951. The arrangement permitted the use of moderately sloping land for plot sizes approaching field conditions. The experiment was designed to compare the effectiveness of different seedbed preparations for the conservation of runoff water for plant growth. The tillage practices conducted on both terraced and unterraced land in a factorial arrangement of plots were plowing, listing, basin listing, and stubble mulch tillage. This report evaluates the experimental technique of such a system of plots and determines the variability experienced and differences assessable from measurements of runoff, soil moisture, and crop yields.

Runoff was measured with type H flumes and Friez FW‐1 waterstage recorders. Amounts and intensities of rainfall were measured by Ferguson recording rain gages and checked by standard gages at 10 points located systematically on the station. Annual yields of winter wheat and soil moisture to a depth of 3 feet at planting and in the spring were measured.

The system for measuring runoff water has been satisfactory. For the 10 years of data, the variability in all quantities measured was high. Nevertheless, significant differences were obtained on a site typical of a large area where soils and slopes were highly variable. The amount of runoff water from the terraced and contour cultivated land was significantly less than that from plots cultivated with the slope. When the four methods of seedbed preparation were compared, stubble mulching significantly reduced the yield of wheat.
Fixation and Release of Potassium by Some Clay Minerals
Authors: Mortland M. M. , Lawton K. , Uehara G.
Published: July 2010

Release of potassium from fixed forms in an illite, montmorillonite, and vermiculite and from the native forms of an illite, biotite, and muscovite was investigated. Methods used in studying potassium release were chemical, electrochemical, and biological. Changes in minerals following potassium release were followed with X‐ray diffraction and chemical techniques. Results of the study indicated the potassium “fixed” by vermiculite and montmorillonite to be available for plant growth. The native potassium of biotite was a great deal more available for plant growth than that of an illite or muscovite.
Some Aspects of the Relationship of Soil, Plant, and Meteorological Factors to Evapotranspiration
Authors: Lemon E. R. , Glaser A. H. , Satterwhite L. E.
Published: July 2010

Evapotranspiration is a function of soil, plant, and meteorological factors. Attempts to predict evapotranspiration without considering all pertinent factors can meet with only qualified success.

It is found that evapotranspiration is controlled by: soil moisture tension, physiological factors, the relation of soil moisture of an irrigated area to that of its surroundings as well as purely meteorological factors of radiation, wind, air temperature, and humidity.

Examples are given of the effects of these factors on measured evapotranspiration.
Water Uptake of Corn Roots as Influenced by Soil Moisture Content and Soil Moisture Tension
Authors: Peters D. B.
Published: July 2010

Experiments conducted on prepared mixtures of a sand and clay soil indicate that the uptake of water by corn roots is a function of the specific moisture content as well as the moisture tension.

The data show that uptake of water and elongation of corn roots are decreased as the moisture tension increases and that the uptake of water and root elongation decreases as the moisture content per unit tension decreases. Calculations made upon the distance from the root surface from which roots extract water indicate that some dynamic factor may be operative in controlling water uptake by plant roots.
Relationships of Atterberg Limits and Cation‐Exchange Capacity to Some Physical Properties of Soil
Authors: Gill William R. , Reaves Carl A.
Published: July 2010

The relationship between some physical and chemical properties of several soils were studied with a view of associating these properties with the mechanical strength of the soils. Shrinkage of natural clods in the tillable range of soil moisture was more closely correlated with the cation‐exchange capacity than with the specific area or the plastic index. The correlations with these values were not as close in the case of puddled soils due to residual shrinkage. The sticky point is more a reflection of the water retention characteristic than a specific indicator of stickiness and has little value in tillage implement design; however, it may be of practical assistance in field work. The modulus of rupture was correlated with the specific area, plastic index, and cation‐exchange capacity of the soils. With the exception of compressibility, the cation‐exchange capacity appeared to be the value most closely correlated with the properties of the soils studied. Since the cationexchange capacity is frequently reported in nonphysical studies of the soil, a significant piece of information of physical property is available which should not be over‐looked.
The Movement of Nitrate Nitrogen Through Columns of Coarse‐Textured Soil Materials
Authors: Bates Thomas E. , Tisdale Samuel L.
Published: July 2010

A laboratory investigation was undertaken in which the movement of nitrate nitrogen through columns of coarse‐textured soil materials was studied. Eight soil materials from the Coastal Plain region of North Carolina were used, and the movement of added nitrates as a function of the porosity of these soils and the quantity of water added to the columns was determined. A multiple regression equation was developed which permitted an estimate of the mean nitrate movement from a knowledge of the value of these two variables.
Control of Magnesium Deficiency in Utah 10B Celery Grown on Organic Soil
Authors: Johnson K. E. E. , Davis J. F. , Benne E. J.
Published: July 2010

This paper reports the results of a 2‐year study of the effects of several compounds of magnesium, potassium, and sodium on magnesium deficiency in Utah 10B celery grown on organic soil. Data obtained show the effects of the treatments on the yields, incidence of magnesium deficiency symptoms in the crops, and composition of the soils on which they were grown. Two to four tons of hydrated magnesium sulphate broadeast and worked into the soil were required to control symptoms of magnesium deficiency in this celery variety. Equally effective control could be obtained by applying 10 pounds of magnesium sulphate per acre in 100 to 150 gallons of water was a foliar spray at 10‐day intervals, beginning 4 weeks after transplanting and continuing throughout the remainder of the growing season. No magnesium carriers used produced any increase in yields of celery, but use of them generally improved quality and increased the value of the crops. Potassium fertilizers individually and jointly with sodium fertilizers tended to increase the incidence of magnesium deficiency symptoms. These symptoms were reduced to a minimum when the exchangeable calcium to magnesium ratio in the soil was less than 3:1 and when the magnesium saturation of the exchange complex was greater than 22%.
Hydraulic Conductivity as Related to Certain Soil Properties in a Number of Great Soil Groups—Sampling Errors Involved
Authors: Mason D. D. , Lutz J. F. , Petersen R. G.
Published: July 2010

This study was undertaken to provide information about hydraulic conductivity, percent large pores, and bulk density, their interrelationships, and the magnitude of the sampling error components involved over a wide range of soil conditions. Data from approximately 10,000 individual core samples from about 900 sites in 7 states, furnished in a cooperative project with the Soil Conservation Service, United States Department of Agriculture, were analyzed. Each sample was classified according to management, genetic unit (great soil group, high family, low family, and series), texture, and horizon.

Mean values for hydraulic conductivity, percent large pores and bulk density, when classified by textural groups, showed a consistent decrease in magnitude with increases in silt and clay content. Mean values for the three properties, when classified by great soil groups, showed consistent differences between groups. Correlations between hydraulic conductivity and percent large pores was positive and comparatively consistent; correlations between hydraulic conductivity and bulk density were negative and generally of a low absolute value. The indicated conclusion was that bulk density, in itself, is a poor indicator of soil permeability.

Variance components for among cores within sites and horizons, and between sites, after removal of all other classifiable variation, indicated that the between site component of the sampling error was 2 to 3 times larger than the within site component. These components are used to estimate “distinguishable permeability classes” for various sampling schemes, and by assuming various cost ratios, optimum sampling rates are estimated.
Soil Aeration as Affected by Organic Matter Application
Authors: Epstein Eliot , Kohnke Helmut
Published: July 2010

The effect of the method of incorporation of organic matter under various conditions of soil moisture and soil compaction on the composition of soil air was the object of this research. Application of fresh chopped alfalfa resulted in a pronounced depression of the oxygen content of the soil air. The order of decreasing oxygen content for the different methods of application was: check > surface mixed > layer at 2‐inch depth > surface application. High moisture content and compaction of the soil increased the time during which the oxygen content remained below 15% at 8‐inch depth. Both the oxygen and the carbon dioxide contents were determined at the 1‐, 3‐, and 8‐inch levels, as well as the amount of carbon dioxide given off at the soil surface.
A Method for Measuring Short‐Term Nutrient Absorption by Plants: I. Phosphorus
Authors: Stanford George , DeMent J. D.
Published: July 2010

A method has been devised which permits measurement of P absorption by plants during relatively short periods of root‐soil contact. Plants are grown without added P in sand during which time a mat of roots develops at the bottom of the container. The exposed root mat with plants intact is then placed in contact with the soil or soil‐fertilizer system. Results obtained using oats as the principal crop and concentrated superphosphate applied to Hartsells fine sandy loam support the following conclusions: (1) P uptake by oats from applied fertilizer increased linearly with time between 1 and 7 days and increased linearly with rates of applied P ranging from 0 to 50 mg. or more per 200 g. soil. (2) Moisture equivalent was approximately the optimum soil moisture level for P absorption. (3) Recovery of applied P commonly ranged from 2 to 5% after absorption periods of 3 to 7 days. The method holds considerable promise as a means of studying the influence of various factors on P absorption by plants. These include environmental factors as well as soil and fertilizer characteristics.
Aluminum, Iron, and pH in Relation to Lime Induced Manganese Deficiencies
Authors: Mehlich A.
Published: July 2010

The effect of freshly precipitated Al‐ and Fe‐oxide hydrates on Mn solubility and uptake by plant roots in relation to pH has been studied. Precipitation of Mn (as Mn (OH)3 or Mn2O3 · XH2O) from MnSO4, by the addition of Ca(OH)2, began at about pH 8.5, while in the presence of Al3+ and Fe3+ salts precipitation began at pH 5.8 and with Fe2+ salts at pH 6.8. Manganese in solution decreased with increasing pH and increasing cation/Mn ratios. In this regard, Fe3+ and Al3+ had a greater effect than Fe2+ while Zn2+ and Cu2+ had the least effect. It was concluded that freshly precipitated sesquioxide hydrates are effective in supplying OH ions for the precipitation of Mn at the lower pH values.

Acid washed H‐roots of soybeans and wheat adsorbed Mn and Al from freshly precipitated Mn‐ and Al‐oxide hydrates. With increasing Al/Mn ratios adsorption of Mn decreased and that of Al increased. Solubilization of Mn and Al was thought to be the result of H ions on roots reacting with the OH groups of the Mn‐ and Al‐oxide hydrates.

Measurement of the nutrient content of soybean and corn tops of varying degrees of chlorosis showed Al and Fe to increase greatly with increasing chlorosis and increasing soil pH. Manganese content was not directly related to either severity of chlorosis or acid soluble soil‐Mn. The Mn content in itself cannot be used, therefore, as a criterion for Mn‐deficiency. It is concluded that excessive amounts of sesquioxide hydrates in soil may contribute to disturbances in the absorption and functional pattern of Mn as well as Ca in plants.
The Effect of Soil Characteristics on the Growth of Quaking Aspen in Northern Minnesota
Authors: Voigt G. K. , Heinselman M. L. , Zasada Z. A.
Published: July 2010

A study was made of the relationship between soil properties and the growth of quaking aspen on 16 sample plots in northern Minnesota. The soils of this region show wide variations in their levels of replaceable bases and other associated fertility factors. The average annual growth of aspen on soils with high levels of calcium, magnesium, potassium, and nitrogen was over 4 times greater than the average annual growth on soils having a lower base status and nitrogen content. Analyses of foliar samples and aspen litter showed a close relationship between the supply of exchangeable bases in the soil on which the trees had grown and the level of calcium, magnesium, and potassium in the tissues of quaking aspen. Although the purposes of the study was primarily reconnaissance, the results show quite conclusively the extreme importance of soil characteristics in determining the quality of a site for aspen growth.
The Residual Effects of Lime Added for the Growth of Various Conifers in Minnesota
Authors: Pawluk Steve , Arneman Harold F.
Published: July 2010

The liming of sandy soils for the growth of various conifers was studied at the Cloquet Forest Experiment Station in northeastern Minnesota. The soil on which the applications were made belonged to the Omega series which is a Brown Podzolic soil developed from red sandy outwash.

Applications were made prior to planting the tree seedlings, and careful growth records were kept for the following 18 years. The residual effects of the various treatments upon the pH of the soils were also established.

The application rates varying from 4 to 20 tons per acre had no noticeable effect on the rate of growth of the trees. The residual effects of lime upon the pH of the soil varied with the amount applied and the length of time after application. The pH remained higher for longer periods of time in the upper horizons with heavier applications of lime.
Oxygen Sorption by Moist Soils and Vermiculite
Authors: Runkles J. R. , Scott A. D. , Nakayama F. S.
Published: July 2010

A standard method of measuring gas adsorption was used to measure the oxygen sorbed by soils and vermiculite that contained varying amounts of water.

The amount of oxygen sorbed by the air‐dry soils was 5 to 8 times that which could be accounted for by solubility in the water alone. Thus, some adsorption of oxygen occurred in the presence of 2 to 6% water. When the soils were oven‐dried at 105°C. for 48 hours, much more oxygen was sorbed. Vermiculite, on the other hand, sorbed a constant amount of oxygen when the moisture content, based on oven drying at 105°C. for 48 hours, was decreased from 50 to 0%. Upon further heating, the vermiculite sorbed less oxygen.

At high moisture contents (50 to 300%), the oxygen sorbed by the vermiculite‐water system was essentially equivalent to the theoretical solubility of oxygen in free water. The oxygen sorbed by the Edina subsoil‐water system at moisture contents between 10 and 25%, on the other hand, was less than the solubility of oxygen in free water.
Calcium Phosphate Fertilizers: I. Availability to Plants and Solubility in Soils Varying in pH
Authors: Terman G. L. , Bouldin D. R. , Lehr J. R.
Published: July 2010

Availabilities of the phosphorus in six pure crystalline calcium phosphates to ryegrass and Sudangrass were determined in the greenhouse. The crops were grown on three acid soils, Clarksville silt loam, Hartsells fine sandy loam, and Edina silt loam; and on two alkaline soils, Rosebud loam and Webster silty clay loam. Dicalcium phosphate dihydrate was appreciably more available than anhydrous dicalcium phosphate on all soils. Monocalcium phosphate was slightly more available than the dicalcium phosphates on the alkaline soils but was less available on the acid soils. Alpha tricalcium phosphate was nearly as available as anhydrous dicalcium phosphate on the acid soils, but was of very low availability on the alkaline soils. Hydroxyapatite was of very low availability on all soils. Availability of octocalcium phosphate was less than for the dicalcium phosphates and decreased with increasing liming rates on Hartsells fine sandy loam. A significant correlation was found between the phosphorus extracted by 0.5N NaHCO3 and the phosphorus uptake by the two crops from the various phosphates. Placing the phosphates in a layer 1½ inches below the surface markedly increased availability to the crops grown in low‐phosphorus Clarksville and Hartsells soils, while mixing with the soil was equally effective in the higher‐phosphorus Edina, Rosebud, and Webster soils.
Replacement of Adsorbed Sodium in Soils by Hydrolysis of Calcium Carbonate
Authors: Bower C. A. , Goertzen J. O.
Published: July 2010

The reaction 2Naadsorbed + CaCO3 + H2O ⇆ Caadsorbed + 2Na+ + HCO3‐ + OH‐ has been studied from the standpoint of describing the replacement of adsorbed Na in calcareous soils subjected to leaching by rainfall. It has been found for the reaction in soils that the equilibrium between solution and adsorbed Na at various water contents can be expressed by the Langmuir equation: Naad = (k1k2Na+)/(1 + k1Na+) where k1 and k2 are constants, and Naad and Na+ are the adsorbed and solution concentrations of Na, respectively. As a consequence of this finding, it has been shown that the concentrations of solution and adsorbed Na at any depth in soil columns after a known amount of leaching with salt‐free water can be satisfactorily predicted by simplified, approximate solutions of equations derived by Thomas, Hiester, and Vermeulen. The results should be especially useful where calcareous soils, which have been affected by sea water, are subsequently leached by rain‐fall.
The Influence of Nitrogen on the Uptake of Phosphorus by a Tomato Test Crop from Three Crop Residues
Authors: Fuller W. H. , Hannapel Ray
Published: July 2010

The uptake of phosphorus from wheat straw, tomato vine, and lettuce residues by a tomato test crop as influenced by different rates of nitrogen additions was studied under greenhouse conditions. The residues were grown in sand‐nutrient cultures at different levels of phosphorus containing the radiophosphorus. The residues were then incorporated into two calcareous soils in greenhouse pots at rates equivalent to 50 and 100 pounds of P2O5 per acre. Nitrogen was applied at rates ranging from 0 to 400 pounds of N per acre 6 inches. The tomato test crop was grown for 9 weeks before harvesting and analyzing.

The results indicated that the percentage of P in the tomato test crop derived from the different residues was not significantly affected by the rate of application of nitrogen to the soil. This circumstance occurred despite the fact that the percentage of nitrogen and phosphorus, and the dry weight of the test crop was influenced by the rate of application of nitrogen fertilizer. The percentage of P in the test crop derived from the crop residues was not affected by nitrogen additions either in a soil deficient in plant‐available phosphorus or one adequately supplied with indigenous available phosphorus. However, the total uptake of plant residue phosphorus by the test crop was significantly influenced by the concentration of phosphorus in the residue.
The Correlation of a Phosphorus Soil Test with the Response of Wheat Through a Modified Mitscherlich Equation
Authors: Bray Roger H.
Published: July 2010

Variations in soil, season, and variety were found not to change the relative response of wheat to a soluble phosphate. But the difference in distribution pattern between the applied and native sorbed phosphorus varied their efficiencies such that the response to the applied phosphorus followed a c log x form of the Mitscherlich equation. Values of c for log x and c1 for b1 were established. When easily acid‐soluble forms are absent these constants can, through soil tests, be used to calculate approximate fertilizer needs and percentage responses obtainable with wheat for a broadcast and double‐disced application of soluble phosphate. The results obtained are in agreement with the writer's nutrient mobility concept.
Soybean Yields as a Function of the Soil Phosphorus Level
Authors: Kamprath E. J. , Miller E. V.
Published: July 2010

A survey was conducted to determine the relationship between the yield of soybeans and the nutrient level of the soil. The yield of soybeans was related to the soil phosphorus level and the soil pH. When the yields of soybeans were placed into the various soil test categories for phosphorus, it was found that the lowest average yield was in the low soil phosphorus category and the highest average yield in the high soil phosphorus range.

Studies in the greenhouse also showed that the yields of soybeans were related to the soil phosphorus level. The response of soybeans to the addition of phosphorus was dependent upon the soil phosphorus level.

A much better evaluation of the effect of the phosphorus level of the soil on the yield of soybeans was obtained by placing the soils into categories ranging from low to very high than was obtained by use of rank correlation.
Ion Exchange in Soil‐Plant Root Environments: III. The Use of Mg28 for the Measurement of Magnesium Absorption by Plants
Authors: Brown D. A. , Wells Joe P.
Published: July 2010

The availability of the Mg28 isotope having a half‐life of 21.3 hours has presented the possibility of its use in the measurement of the available magnesium in soils. Data are presented to show the relative proportions of fertilizer and soil magnesium adsorbed by cation‐exchange resin sheets over time periods up to 96 hours. The percentage of magnesium adsorbed from the tagged magnesium fertilizer remained relatively constant for exchange periods from 48 to 96 hours; being of the order of 76.6, 57.8, and 53.9% for soils with 50, 150, and 250 pounds per acre of exchangeable magnesium, respectively.

Four‐week‐old corn plants adsorbed adequate Mg28 during a 96‐hour period for radioactive analysis of the nonadsorbed, adsorbed magnesium on corn roots, and permitted the analysis of the absorbed magnesium in the roots and tops. Increasing the rate of magnesium fertilizer increased the percentage of magnesium derived from the fertilizer in each of the different stages of nutrient uptake. Conversely, at any one fertilization rate, increasing the level of soil magnesium reduced the percentage of magnesium derived from the applied fertilizer.

These data indicate that the Mg28 isotope is usable up to periods of at least 7 half‐lives for nutrient uptake and cation‐exchange studies.
Studies of Phosphorus Availability in Organic Soils
Authors: Larsen J. E. , Warren G. F. , Langston Ruble
Published: July 2010

Experiments were conducted on the phosphorus status of organic soils by correlating the phosphorus solubility in various extractants with percentage yields of tomato, peppermint, and onion. Seven different extractants, including water, were compared using four ratios of soil volume to extractant volume. Distilled water extracts gave the most accurate estimates of plant‐available phosphorus in a ratio of soil volume to extracting solution of 1:20 for the organic soils and 1:10 for the mineral soil.

The threshold value at which yields were not increased with additional applications of phosphorus under greenhouse conditions was established at 10 and 16 pounds per acre of water‐soluble phosphorus when the soil and the water was shaken for 2 minutes and 30 minutes, respectively.
Compaction Tests as a Means of Soil Structure Evaluation
Authors: Kawano Y. , Holmes W. E.
Published: July 2010

Compaction test data from the surface horizons and subsoils of 15 soils were analyzed to evaluate the most suitable data for correlations with percent carbon and percent clay. Percent pore space at maximum bulk density when correlated with either percent carbon or percent clay yielded correlation coefficients of greater statistical significance than did maximum bulk density when so correlated. This is probably because of the variations in particle (mineral) densities of the soils investigated. The particle densities will to some extent influence the maximum bulk densities attained with any compaction test, but percent pore space at maximum bulk density is not so influenced. It was concluded that unless the soils undergoing investigation have essentially the same particle densities, percent pore space at maximum bulk density is a better choice of data for correlation studies than is the maximum bulk density.

Percent pore saturation at maximum density was not found to be a suitable correlation variable. A statistical highly significant correlation coefficient was obtained when optimum moisture (standard Proctor test) was correlated with plastic limit.

Compaction test data from 5 montmorillonitic clay soils were compared to those from 5 kaolinitic clay soils. These comparisons failed to indicate that the montmorillonitic clay soils were more susceptible to compaction from mechanical forces than were the kaolinitic clays. Montmorillonitic clays did, however, have significantly higher liquid limits and plastic indices.
Effect of Drying Cycles on Changes in Resistance of Soil Moisture Units
Authors: Cannell Glen H.
Published: July 2010

Several different types of electrical resistance units were tested for displacement of calibration curves using a wetting‐drying regime. The experiment was carried out in a temperature‐light controlled growth chamber, and was designed to simulate field conditions with respect to moisture treatments; (1) excessive‐leaching, and (2) slight‐leaching.

A cover crop of oats was used as a means to reduce the moisture content to near the wilting percentage in each drying cycle. Growth of the crop was controlled by clipping which permitted drying periods with intervals of nearly 7 days. Changes in moisture content during the drying cycle were obtained by use of a solution balance. Block resistance readings were recorded at the time weights were taken.

Statistical analyses were made at several soil suctions for the 1st, 6th, and 11th drying cycles. The differences between drying cycles were statistically significant.

Analyses of variability were calculated and comparisons made between blocks of a given type and between different block types at various soil suctions. In general, variability between blocks of one type increased with soil suction. However, the increase was not always consistent between different types of blocks.
Aluminum in Soils: I. Extraction Methods and Magnitudes in Clays and Ohio Soils
Authors: McLean E. O. , Heddleson M. R. , Bartlett R. J. , Holowaychuk N.
Published: July 2010

Various procedures were used for extraction of Al from Ohio soils representing a wide range in extractable Al. One normal NH4OAc at pH 4.8 was selected as an extracting solution because of its superiority over Ba(OAc)2 and BaCl2. One normal NH4OAc plus 0.2 N BaCl2 was no better than NH4OAc alone. At this pH it extracts enough Al from most soils for accurate measurement with little possibility of damage to the clay crystal.

Eight Ohio soils were electrodialyzed and resaturated to various levels with K and/or Ca. Extractable Al was determined in these soils after equilibration. At the zero‐base added level, the extracted Al ranged from 4.7 me. per 100 g. of soil in the Wooster to 19.8 in the Hoytville. Increased saturation with K and/or Ca decreased the amount of Al extracted. Somewhat more Al was obtained from K‐soils than from Ca‐soils even though the pH values of the former were higher. Comparable studies with illite, bentonite, kaolinite, Putnam subsoil clay, vermiculite, and chlorite were also made.

The importance of Al at the magnitudes found in the field and laboratory soils is discussed. The general failure of existing soil tests for lime requirement to adequately account for the Al in acid soils was considered. The possibility of Al interfering in various chemical and biological studies is mentioned.
Replaceability of Ammonium in Vermiculite with Acid Solutions
Authors: Scott A. D. , Hanway J. J. , Edwards A. P.
Published: July 2010

NH4‐saturated samples of Montana vermiculite were extracted with 1N Na, 1N K, and 0.1N acid solutions that varied in pH. In some cases, successive and continuous extractions with boiling solutions were used. In others, the vermiculite samples were leached or distilled with solutions at room temperature.

More NH4 was removed by the Na solutions as the pH of the extracting solution increased or decreased from neutrality. When the accumulation of replaced NH4 in the extracting solution was reduced by using alkaline solutions or by using the successive extraction method with the acid solutions there was an increase in the amount of NH4 removed. In a given extraction period the amount of NH4 removed by acid Na solutions increased linearily as the solution pH decreased.

More NH4 was removed by the K solutions as the pH of the extracting solution decreased. In the presence of a high concentration of a nonvolatile fixable cation (K) the alkaline solutions removed the least amount of NH4.

There was little effect of pH on the amount of NH4 removed by 0.1N acid solutions when the solution pH was above 3. When the pH of the acid solutions was decreased below 3, there was a rapid increase in the amount of NH4 removed.
The Apparent Mobilities of Exchangeable Alkali Metal Cations in Bentonite‐Water Systems
Authors: Low Philip F.
Published: July 2010

A direct current conductivity method was devised for determining the mobilities of exchangeable cations on close‐packed clays in water. The method was applied to the determination, at several temperatures, of the apparent mobilities of K, Na, and Li ions on the respective, homoionic bentonites. The apparent mobilities were in the order Na > Li > K.

An Arrhenius type equation was used to calculate the activation energies for movement of the adsorbed ions. The observed activation energies were larger than those for the same ions in solution and were in the order Na > Li > K. The reasons for these observations were discussed and it was concluded that, in each case, the activation energy was due largely to the energy required to form a hole, into which the ion could move, in the adsorbed water.
Response of Corn in Superphosphate Placement Experiment
Authors: Robertson W. K. , Hutton Curtis E. , Thompson L. G.
Published: July 2010

Phosphorus was placed 2, 8, 14, and 20 inches deep in Norfolk loamy fine sand and Red Bay fine sandy loam.

In dry years the deeper treatments gave significantly more corn than the shallow treatments when the surface soil had residual fertilizer phosphorus, except on the Red Bay fine sandy loam where placement in the 8‐inch level gave a lower yield than the 2‐inch level. This was probably because the placement was in the plow sole area which was so compact that roots could not develop. When no residual phosphorus was present on Red Bay soil, the 2‐inch treatment gave the best yields. This was because there was not enough phosphorus in the surface soil to promote growth of roots to the fertilizer band and the corn receiving the deeper placements was not stimulated.

In wet years corn was able to et sufficient phosphorus from residual fertilizer to promote root penetration, and subsoiling alone was as effective in increasing corn yields as was applied phosphorus.
The Effect of Soil Phosphorus Compounds on Soil Test Correlation
Authors: Bishop William D. , Barber Stanley A.
Published: July 2010

Twenty soils representing the level upland and the depressional soils in the hydromorphic sequence of profiles of the upland and lake plain catenas were characterized by the determination of pH, organic matter, clay content, acid‐soluble phosphorus, water‐soluble phosphorus, alkali‐soluble phosphorus, organic phosphorus, and iron content.

When the above variables were included in a multiple correlation analysis using yield of phosphorus as the dependent variable, a multiple correlation coefficient of 0.931 was obtained. The elimination of all variables except acid‐soluble and alkali‐soluble phosphorus gave a multiple correlation coefficient of 0.851. The simple correlation coefficient for acid‐soluble phosphorus was 0.557 and for alkali‐soluble phosphorus 0.675. The increase in correlation where both acid‐soluble and alkali‐soluble phosphorus were used over the correlation for either one alone was significant at the 1% level. Hence, the use of both acid‐soluble and alkali‐soluble phosphorus were required to explain the contribution of the different soil phosphorus compounds to yield.

Solubility curves of the 20 soils indicated that the soils were heterogeneous with respect to soil phosphorus compounds. The depressional soils from the lake plain catena contained more calcium phosphate and less iron and aluminum phosphate compounds than their counterpart in the upland catena.

Solubility curves for calcium phytate and other organic phosphorus compounds indicate that they are partially acid‐soluble, suggesting that an acid extraction contains phosphorus from both organic and inorganic sources. This was supported by the fact that a significant correlation was obtained between organic matter and acid‐soluble phosphorus.
Site Index Comparisons for Several Forest Species in the Southern Appalachians
Authors: Doolittle Warren T.
Published: July 2010

This paper gives methods and results of a study of relationships of site indices of 10 tree species common in the Southern Appalachians. These species are: scarlet oak, black oak, northern red oak, chestnut oak, white oak, white pine, shortleaf pine, pitch pine, Virginia pine, and yellow‐poplar. Site indices of the 10 species were correlated by regression methods so that when the site index of 1 species is known for a given piece of land, it is possible to determine, by use of equations or a chart, the site index for 1 or all of the other 9 species. Results of a special field test showed that the standard error of estimate for predicting site index of scarlet oak from other species was ±5.36 feet by using equations and ±5.28 feet by using the chart. White pine had the highest site index on all lands or sites except on the best, where yellow‐poplar was superior. Of all species, the chart shows that yellow‐poplar is the most responsive to site change; it has the highest site index on the best sites and the lowest site index on the poorest sites.
Nature of the Reactions of Monocalcium Phosphate Monohydrate in Soils: I. The Solution That Reacts with the Soil
Authors: Lindsay W. L. , Stephenson H. F.
Published: July 2010

The dissolution of monocalcium phosphate monohydrate (MCP) in water was followed over a 17‐day period; and the resulting solution was compared with solubility isotherms of the system CaO‐P2O5‐H2O at 25°C. Shaking excess MCP with water at room temperature resulted in rapid dissolution during the first few minutes. Within an hour and continuing for more than 24 hours, the solution was in metastable equilibrium with newly formed dicalcium phosphate (DCP) dihydrate and undissolved MCP. The composition of the solution later changed as anhydrous DCP slowly precipitated and the first‐formed DCP dihydrate dissolved. The final solution was in equilibrium with anhydrous DCP and undissolved MCP.

Band placement of MCP in soil was found to initiate a series of reactions. The solution phase from the reaction zone was sampled by means of filter papers separating several 5‐mm. layers of Hartsells fine sandy loam. Reduced water vapor pressure at the fertilizer band caused water to move inward from the surrounding soil. This transport of moisture resulted from both liquid and vapor movement. A wetted zone formed in the immediate vicinity of the band. The solution sampled at the fertilizer band approximated very closely the composition of the metastable triple‐point solution (MTPS) in which P is 3.98M, Ca 1.44M, and pH 1.48. This highly concentrated solution moved slowly away from the fertilizer band into the partially dried soil, dissolving Fe, Al, Mn, and other constituents from the soil. In this complex chemical matrix many different phosphate compounds of Fe, Al, Ca, and Mn are expected to precipitate as the solution reacts with more soil and pH rises gradually to that of the surrounding soil. Water continued to move into the fertilizer zone even after MCP had dissolved. This caused dilution of the first‐formed solution and enabled it to move farther into the surrounding soil.