bluuebunny/crossref_metadata_2025_split huggingface dataset:
Correlation Between Nitrifiable Nitrogen and Yield Response of Corn to Nitrogen Fertilization on Iowa Soils
Authors: Fitts J. W. , Bartholomew W. V. , Heidel H. 
Published: July 2010

AbstractNitrification rate is proposed as a procedure for evaluating nitrogen requirements of soils for the production of corn. By the use of a modified nitrification method the rate of nitrate production was compared with the response of corn to nitrogen fertilizer in a series of experiments conducted in Iowa over a period of seven years. A significant correlation was obtained between nitrification rate and the response of corn to the application of 40 to 60 lbs. of nitrogen per acre. The data serve to stress the influence of plant population density on the magnitude of yield response to nitrogen. At comparable rates of nitrification considerably higher yield responses to fertilization were obtained where the plant population was high than where it was low. In all population groups, however, a profitable yield response to nitrogen fertilization was obtained where the nitrification rate was less than 40 ppm. On fields with thick stands, profitable yield increases were generally obtained when the nitrification rate was less than 50 ppm.
Soil Mapping by Stereoscopic Interpretation of Airphotos
Authors: Pasto Jerome K. 
Published: July 2010

AbstractIn many areas it appears possible to map soils, with some generalization, by combining stereoscopic interpretation of aerial photographs with field checks. As a test of this technique, the soil series were mapped on 4000 acres in the glaciated region of southern New York. The area was then mapped on foot in the usual manner. The stereo results came remarkably close to representing the true field conditions.Essentially the method relies on knowledge of the kinds of soil which occur in the area, then identifying certain features of the land related to soil patterns. The major features on airphotos important to soil identification are the landscape or land form, slope, position, color tone, vegetation, drainage pattern, and land use.In complex areas soil mapping obviously depends on field examination, but where stereo methods can be applied more maps could be made available for use, with a big saving in time and money.
Field Structure of Cultivated Soils with Special Reference to Erodibility by Wind
Authors: Chepil W. S. 
Published: July 2010

AbstractA study of structure and erodibility of soil by wind was carried out on wind eroded and residual soil materials in a condition usually existing in the field and after sampling, cultivating, and dry sieving.Field structure and erodibility of soils varied greatly with as little as 1 inch of simulated rainfall. In soils undisturbed by cultivation after rain, four distinct phases of structure were found, all of which possess different degrees of erodibility by wind. These phases are the primary aggregates (water‐stable aggregates), the secondary aggregates (granules and clods), the surface crust, and the consolidated soil material between the secondary aggregates.The abrasive action of wind erosion was shown to be one of the most serious aspects of erodibility by wind.The mechanical stability, that is, the resistance of a soil to breakdown by mechanical forces such as cultivation or sieving, was found to vary directly with the resistance of the soil to abrasion by wind‐blown sand. Mechanical stability was greatest for drift particles (sand grains and water‐stable aggregates mostly), less for the secondary aggregates, followed in order by the surface crust, the consolidated materials between the secondary aggregates, and lastly the consolidated materials, if any, which held drifted particles together after they were wetted and dried.The amount of dispersed fine silt was found to be a primary factor influencing the formation of the surface crust and the consolidation of the soil body after it was wetted and dried. A fraction of clay size, being much less dispersible than silt, was found to be the primary factor of secondary aggregate formation. Water‐dispersible silt and clay were responsible in large measure for the resistance of the soil to erosion by wind. Although the amount of erosion was limited to some degree by the presence of water‐stable aggregates too large to be moved by wind, it was found that cultivated dryland soils lack these aggregates in sufficient amounts. The resistance of these soils to wind action was found to depend primarily on their ability to form secondary aggregates, or clods.The secondary aggregates preserved their identity below the surface even after repeated wetting and drying in the field. It was concluded, therefore, that the physical condition of the soil is indicated as well or better by methods such as dry sieving, which primarily measure the state of the secondary aggregates, than by methods that measure the state of the primary aggregates.
Factors Affecting Distributions of Cations in Clay‐Electrolyte Systems
Authors: Harward Moyle E. , Mehlich A. 
Published: July 2010

AbstractInvestigations were conducted on some factors which influence distributions of K and Ca in clay‐electrolyte systems.The method involved the additions of acids to variously base saturated suspensions of Utah bentonite and Kamec halloysite. The distributions of K and Ca were determined from an analysis of the supernatant liquid after equilibrium was obtained.The results suggest that the effect of Ca‐saturation upon the replacement of K is related to type of colloid and to the amount of acid added. When HCl in amounts greater than 0.09 symmetry were added to Utah bentonite systems, the amount of K in solution increased with Ca‐saturation, reached a maximum and then decreased. The degree of Ca‐saturation at which the maximum amount of K was in solution was dependent upon the amount of acid added to these systems.Appreciable amounts of K and Ca were in solution when no electrolyte was added. Under these conditions K and Ca in solution increased with increasing degree of Ca‐saturation and they were greater in Kamec halloysite than in Utah bentonite systems. When small amounts of acid were added, however, the amounts of K and Ca in solution were greater for the Utah bentonite than for the Kamec halloysite systems at low degrees of base saturation while the reverse was true at high degrees of saturation. The addition of small amounts of acid did not change the trend of K in solution increasing with Ca‐saturation for both clays.The influence of some partially ionized solution species upon the replacement of K was investigated by using acids with different dissociation constants. The data suggested that differences between acids will only be evident if the pH of the equilibrium solutions are below that at which the acids are ordinarily neutralized.
The Influence of Sodium, Potassium, and Ammonium Ions on the Respiration of Azotobacter chroococcum as Related to the Composition of the Growth Medium
Authors: Burns C. M. , Harris John O. 
Published: July 2010

AbstractAzotobacter chroococcum was able to grow in modified culture media deficient in potassium and sodium ions. Respiratory activity of the resulting cells in the presence of added potassium or sodium ions was influenced by the composition of the growth medium. Ammonium ions gave increased oxygen uptake regardless of the growth medium. When the cells were grown in ammonium‐Ashby's medium potassium stimulated while sodium retarded oxygen uptake. Cells harvested from the sodium medium exhibited decreased respiratory activity in the presence of potassium ions. Potassium stimulation of respiration of cells grown in the ammonium rich medium appeared to be of a general nature rather than specific for a single enzymatic process. The presence of potassium ions increased the rate at which the cells could adapt themselves to heterologous respiratory substrates.
Using Soil Survey Information in Land Valuation for Tax Assessment
Authors: Aandahl Andrew R. 
Published: July 2010

AbstractSoil surveys are a tool for improving the assessment of rural lands. The soil classification provides the means for utilizing factual information in making the necessary physical predictions of soil productivity. With these predictions economic ratings for different uses of each soil can be made. The soil map showing the location and extent of each soil permits the application of these economic ratings to specific tracts of land resulting in the first approximation of the assessed value. These must be adjusted for roads, schools, and other factors affecting the value.
Foliar Feeding of Corn with Urea Nitrogen
Authors: Foy C. D. , Montenegro G. , Barber S. A. 
Published: July 2010

AbstractThe application of supplemental nitrogen to corn by the use of urea foliar sprays was investigated. Injury in the form of marginal leaf burn was dependent upon both the concentration of the solution and the rate of application. The amount of injury could also be modified by additions of sugar, calcium hydroxide and potassium bicarbonate. Yield response of corn to foliar applied nitrogen was no greater than to the same amount of nitrogen applied as a side dressing. When injury occurred the yield response was reduced. The cause of the marginal leaf burn was investigated. Ammonia or nitrites did not appear to cause the injury. It was postulated that some product or a number of products of ammonia metabolism caused the injury. The beneficial effect of sucrose was believed to be due to the decreased rate of urea absorption and an increased rate of urea translocation within the plant.
Selective Loss of Plant Nutrients by Erosion
Authors: Stoltenberg N. L. , White J. L. 
Published: July 2010

AbstractLosses of soil and plant nutrients have been determined for six 3‐acre watersheds under prevailing farming practices, and six 3‐acre watersheds under a conservation farming system. The period reported, 1947–1950, was found to be close to normal with respect to rainfall. Comparative loss data was also obtained for the four crops represented on the watersheds, namely, corn, soybeans, wheat, and meadow.Erosion was found to be a selective process such that the eroded material contained considerably more plant nutrients than the soil from which it was eroded. This selective process resulted in a decrease in soil fertility, a decrease in organic matter, and changes in texture. The selective nature of the erosion process was found to be due to energy limitations of the runoff.It was found that as selective erosion progressed, the availability of certain soil fractions may be changed, which limited the selection. For areas under cultivation, the effects of selective erosion were found to be accentuated by increases in the availability of the more valuable soil constituents as a result of plowing, cultivation, or rill development. Evidence was obtained in contradiction to the concept that slight or geological erosion is a beneficial soil forming process.
Capillary Intake Rate of Water and Soil Structure
Authors: Swartzendruber Dale , De Boodt M. F. , Kirkham Don 
Published: July 2010

AbstractRate of capillary absorption of water in soils was measured and compared with some other physical measurements as a possible index of structure. Disturbed and undisturbed samples were used. The disturbed samples were treated in two ways. Part were incubated in the presence of moisture and nutrient solution; part were mixed with a synthetic conditioner. After the disturbed samples were treated, they were air‐dried and screened to the size range 0.25–2.00 mm. Only this range of aggregate sizes was used in subsequent determinations. The undisturbed samples were cubes, I inch on an edge, sawed from larger, air‐dry clods, taken originally from moist, but not wet soil profiles, some in good structure, some in poor.The structure measurements, which were used for the disturbed samples to adjudge the value of the capillary absorption rate as a structure index, were hydraulic conductivity and water stability of aggregates. For the undisturbed samples the comparison measurements were capillary porosity and aeration porosity.For those disturbed samples which were incubated, and for those undisturbed samples which were taken in the A soil horizon, no significantly consistent relationships were found between the capillary absorption rate and the comparison measurements. For those disturbed samples treated with the synthetic soil conditioner, and for those cube samples taken below the A‐horizon, there were found significant or highly significant correlations with the comparison measurements. The action of organic matter on the wetting angle of the soil is believed to have caused the non‐significant results for the incubated samples and for the samples from the A‐horizon.It is concluded that for soils containing variable amounts and kinds of organic matter, the capillary intake rate is not a reliable index of structure; but that for soils containing constant amounts and kinds of organic matter the capillary intake rate should be satisfactory.An idealized capillary tube model of soil is presented as an aid in interpreting results. The model shows that with a constant wetting angle, the capillary absorption rate should be an index of structure. But the same model shows that hydraulic conductivity should be a better index than the capillary absorption rate. The last statement is in agreement with the experiments.The existence of tables is reported for determining other statistical levels than the usual 1% or 5%. These tables are utilized to calculate specific levels for some of the data.
Multiple Tensiometer for Determining the Vertical Component of the Hydraulic Gradient in Soil
Authors: Richards L. A. 
Published: July 2010

AbstractA description is given of an instrument for measuring the hydraulic head and hydraulic gradient of water in unsaturated field soil. Porous ceramic sections are mounted between plastic spacers to make a rod‐shaped instrument for insertion in a hole made by the Standard Veihmeyer soil sampling tube. Five porous sections with a vertical spacing of 10 cm, are thus arranged with individual connections to mercury manometers mounted at the top of the assembly.During infiltration, after 44 cm of water had entered a deep, uniform, fine sandy loam, the downward hydraulic gradient averaged 1.3 in the 10–30 cm depth interval. This corresponds to a downward water‐moving force of 1.3 g. Six days later, a few hours after a 1‐cm rain, the average downward water‐moving force in the same depth interval was 5 g. Four days after the rain, there was a net upward water‐moving force of 36 g in the 10–20 cm depth interval, due to the influence of surface evaporation. A much higher value existed in the 0–10 cm layer because of the greater moisture gradient near the soil surface.The term static zone is used in connection with the soil‐water system to designate the locus of points above which water movement is upward, and below which water movement is downward. A static zone passes downward through fallow soil following wetting. Over a four‐day period of warm dry weather following a heavy irrigation, the static zone passed downward at an average rate of 6 cm per day in a fallow fine sandy loam.
Seasonal Fluctuations in Soil Structure and Erodibility of Soil by Wind
Authors: Chepil W. S. 
Published: July 2010

AbstractThe objective of this investigation was to elucidate the effects of seasons on soil structure and erodibility by wind.Little change in soil structure and erodibility occurred during a mild, dry winter near Lubbock, Tex., in 1952–53, but considerable change occurred during several consecutive winters in some areas of the Prairie soil zone of Kansas where the soils were usually moist.Under moist conditions, frost action tended to break down the coarse water‐stable aggregates and at the same time tended to consolidate the finest fractions to an intermediate size, especially between 0.05 and 0.42 mm. in diameter. The probable mechanism of frost action on soil structure is described.Secondary aggregates and clods tended to break down during the winter to a size erodible by wind (<0.84 mm. in diameter). Soil erodibility was in most cases much higher in spring than in fall. The greatest increase in erodibility occurred in finest textured soils, the least in coarsest. Seasonal fluctuations in soil structure and erodibility seldom exceeded 3 inches in depth. Below this depth, the structure and erodibility changed little from season to season.During the summer there was usually an increase in the coarsest and the finest water‐stable soil fractions. It was concluded that the finest water‐stable fraction (<0.02 mm.) contains materials essential for the building of primary and secondary soil aggregates.
Separation of Organic Acids from Several Dormant and Incubated Ohio Soils
Authors: Schwartz S. M. , Varner J. E. , Martin W. P. 
Published: July 2010

AbstractThe objectives of this study were to determine the organic acid content of several of the Grey‐Brown Podzolic soils in Ohio and to study changes in the acids occurring as a result of short period aerobic incubatious of the soil materials at constant temperature and moisture.The soil materials used in this investigation, Brookston silty clay loam, Crosby silt loam, Miami silt loam, and Wooster silt loam, were obtained from naturally wooded areas in the state.A chromatographic column containing silica gel was employed for the separation of the organic acids. This procedure permitted the separation and quantitative estimation of the organic acids extracted with ether from the soil material. The identities of the organic acids were indicated by a comparison of their positions on an elution calibration chart with those of known pure organic acids. The chromatographically separated acids were not chemically characterized.It was found that of the organic acids separated by this procedure, only two occurred in significant amounts, namely acetic and formic acids. In addition, very small quantities of other acids, including succinic and lactic acids and what are thought to be a group of high‐molecular weight fatty acids, were also separated. The latter probably resulted from alkali hydrolysis of the fats extracted from the soil materials.A 1% glucose treatment of the several soil materials apparently did not appreciably change the organic acid make‐up either qualitatively or quantitatively. Preliminary data are presented concerning the effect of incubation on phosphorus solubility.
Some Empirical Relations of Soil‐Moisture Tensions
Authors: Miller W. McNab 
Published: July 2010

AbstractAn analysis was made to compare methods of designating soil mositure tension for an entire irrigation season. Using the field data from a sugar‐beet irrigation experiment, seasonal values for soil‐moisture tension at a given depth were calculated as a simple mean of all readings, and as a mean of the tensions just prior to each irrigation. These values were found to correlate closely with mean tensions calculated similarly to Taylor's mean integrated tension for a single depth. Yields were found to correlate equally well with either mean integrated tension or the mean of tensions prior to irrigation. Under soil and growth conditions encountered, no advantage was found in using mean integrated soil‐moisture tension or the arithmetic mean of all readings, in preference to the simpler mean of pre‐irrigation tensions.
Nutritional Groups of Soil Bacteria on the Roots of Barley and Oats
Authors: Wallage R. H. , King H. deL. 
Published: July 2010

AbstractBarley and oats were grown each in five replicate field plots. At two stages of growth, namely the “tiller” and “head” stages, plants were removed and bacteria were isolated from composite samples of soil that adhered to the roots. Bacteria were also isolated from the soil between the rows of plants. The bacteria then were arranged into seven groups according to their growth in a variety of nutritional media; in general it was found that those requiring yeast extract occurred with the greatest frequency. The results were analysed statistically and it was found that specific ‘rhizosphere effects’ existed chiefly in relation to the age of the plants, and that those effects occurred more frequently with regard to barley than with oats. It was concluded that root excretions in the rhizosphere soils of barley and oats had little or no effect on the equilibrium of the nutritional groups. Emphasis is placed on the importance of replicating samples and analysing results statistically.
The Effect of Stubble Mulching on the Acid Soluble and Adsorbed Phosphorus in the Soil
Authors: Withee L. V. , McCalla T. M. 
Published: July 2010

AbstractPlots having a 13‐ and 15‐year history of continuous plowing and stubble mulching were sampled and analyzed to determine if the two tillage practices had resulted in differences in the phosphorus content of the tilled layer. The plots were selected from two series of rotations of high and low fertility level established for the study of stubble mulching in relation to erosion, moisture storage and crop yields. The plots were sampled in three layers, 0 to 1, 1 to 3, and 3 to 6 inches. Determinations of acid soluble and adsorbed phosphorus were made on each of the composited soil samples.There was a significant increase in the acid soluble and adsorbed phosphorus content of the surface inch of soil over that in the 3 to 6 inch layer of the subtilled plots. The variation in the acid soluble or adsorbed phosphorus in different depths of the plowed plots was consistently less than that of the stubble mulch plots. In all instances the subtilled plots contained more acid soluble and adsorbed phosphorus in the surface inch than did the plowed plots. There was very little difference in the phosphorus content of the 0 to 6 inch depth of the plots in stubble mulching or plowing.
A Comparison of Ammonium Acetate, Barium Acetate, and Buffered Barium Chloride Methods of Determining Cation Exchange Capacity
Authors: Pratt P. F. , Holowaychuk N. 
Published: July 2010

AbstractThe cation exchange capacities of several profile samples of soils were determined using three different methods. Total exchangeable cations were determined and used as a criterion for evaluating the different methods of determining the exchange capacity. For all soil samples the NH4OAc method underestimated the exchange capacity and so produced distorted exchange capacity profiles. The Ba(OAc)2 method gave exchange capacity values which were equal to the sum of exchangeable cations, except with highly acid soils where it gave low values. The BaCl2‐buffer exchange capacity gave values that were nearly equal to the sum of the exchangeable cations for all samples tested. The Ba(OAc)2 or BaCl2‐buffer methods, in which Ba is replaced by 0.05 N HCl and the Ba determined using an acetylene flame with a model 52 C Perkin‐Elmer photometer, cannot be used for some samples because of Ca interference. Some slightly acid soils gave sufficient Ca release during the HCl extraction to interfere in the Ba determination. This interference was removed by washing the soil with HCl before leaching with the BaCl2‐buffer and by replacing the barium with NH4OAc.