bluuebunny/crossref_metadata_2025 huggingface dataset:
A Turbidimetric Potassium Determination Affected Little by Temperature
Authors: Olson R. V.
Published: July 2010

A modification of the turbidimetric cobaltinitrite method for determining potassium is presented. The method is applicable to use in routine soil testing laboratories and has been in use for 3 years in Kansas county laboratories.

The method is not appreciably affected by temperature changes over the temperature range of 15° to 35° C but is subject to errors at temperatures greater than this. Comparisons of the effect of temperature on this method with two methods now in common use showed it to be subject to less error.

The effects of temperature have been minimized by modifying the usual techniques in two ways: (1) by selecting the proper wave length and adjusting the photometer with a blank solution to prevent measurement of the amount of color in the solution phase, and (2) by introducing sodium cobaltinitrite powder directly into the potassium solution‐alcohol mixture, resulting in slow formation of the potassium precipitate.
Field Capacity in Laboratory Columns
Authors: Miller Robert D. , McMurdie John L.
Published: July 2010

It is shown that the material decrease in downward movement observed as soils approach field capacity cannot be explained in terms of capillary conductivity alone. Instead, the combined effects of decreasing capillary conductivity in the drying zone, hysteresis and reduced hydraulic gradients at all levels are involved. The capillary conductivity of the drying zone is always greater (probably much greater) than that of the wetting zone. Hysteresis effects, if present, ought to result in larger reductions in hydraulic gradient for an increment of water transfer than would occur without hysteresis. The hydraulic gradients at all levels ought to decline during drainage.

Experimental evidence is presented which is in general agreement with expectations. Hysteresis effects were large, and the hydranlic gradients greatly diminished after 48 hours of drainage.
Water Entry and Downward Movement in Undisturbed Soil Cores
Authors: Taylor Sterling A. , Heuser Neil C.
Published: July 2010

Water moves downward in a dry soil from a constant source at the surface according to Darcy's law which, combined with the law of conservation of mass, results in an equation for the downward flow of water in unsaturated soils. This equation has previously been discussed and solved for special conditions. This paper reports progress that has been made in measuring and evaluating the components of this equation for undisturbed soil cores.

Six undisturbed cores 10 cm in diameter and 120 cm long and containing different amounts of water were used. Water was allowed to enter the core under a constant head of 1.2 cm. The quantity of water that accumulated in the soil and the depth to the wetting front were measured as functions of time. The soil moisture potential was measured at 5 cm intervals of depth and at various time intervals. From these measurements infiltration rates, moisture potential gradients, and apparent moisture conductivities were calculated. Moisture conductivity was calculated from the moisture retention curve as suggested by Childs and Collis‐George; this technique has not been experimentally verified sufficiently to justify the calculation of the conductivity gradient, hence the flow equation has not been completely solved.

The results indicate that the infiltration rate depends primarily on the gradient of the moisture potential and has secondary dependence on the capillary conductivity. Potential gradients in the wetting zone and across the wetting front may be much greater than in the transmission zone and they appear to be a principal factor in determining infiltration rates. Potential gradients were measured and used to calculate apparent capillary conductivity values which are always smaller than infiltration rates. As a result of large potential gradients, the infiltration rates exceeded the saturated permeability in five of the six cores studied.
Factors Affecting Adsorption of Cations by Plant Roots
Authors: Mehlich A.
Published: July 2010

The adsorption of Ca, Mg, K and Na by metabolically inactive H‐roots of wheat and alfalfa in relation to the nature of the anion has been studied. Titration curves and fH values showed wheat roots to have a weaker acid character than alfalfa roots. A high retention of H+ over metal cations was indicated. As a consequence, only small amounts of cations were adsorbed when offered as nitrates, but large amounts were adsorbed when offered as the bicarbonates. The order of increasing adsorption in either case was: Na, K, Mg, Ca.

When Ca, Mg and K were offered in exchangeable form on a soil colloid with Ca/Mg and Ca/K ratios of 4, the Ca/Mg ratios on the roots were 4 and 8, and the Ca/K ratios were 10 and 24 for the wheat and alfalfa roots, respectively. The corresponding distribution of cations on the wheat roots were: Ca, 73%; Mg, 19%; K, 8%; and for alfalfa roots they were: Ca, 85%; Mg, 11%; and K, 4%.

It is concluded that the adsorption of cations by metabolically inactive roots is a neutralization reaction involving principally Ca. The group of compounds involved in this reaction have been designated as RCOOH. Selective adsorption of cations involving exchange reaction, notably Mg and K, through RH is restricted to metabolically active roots. It is suggested that the proportions of K to Ca entering the plant is related to the concentration and proportion of RH to RCOOH of roots.
Potassium Competition in Grass‐Legume Associations as a Function of Root Cation Exchange Capacity
Authors: Gray Bryce , Drake Mack , Colby Wm. G.
Published: July 2010

Ladino clover, smooth brome grass. Kentucky bluegrass and bentgrass were grown in greenhouse pots to determine the relative uptake of K by the species when grown separately, and to study the competition for K when Ladino clover was grown in association with each of the three grasses. This was to determine to what extent the theory of differential cation uptake by plants of different root cation exchange capacity can explain the disappearance of legumes from pasture mixtures as a result of plant competition for K. Potassium uptake by plant species at low levels of soil K was closely correlated with root cation exchange capacity. The relative K compatibility was smooth brome (best). Kentucky blue (intermediate) and bentgrass (poorest). Because of the strong attraction and high uptake of K by roots of bentgrass, it was impossible with practical rates of K fertilization to maintain an adequate K supply for the associated Ladino clover.
Rice — Soil Conserving or Soil Depleting?
Authors: Green Victor E.
Published: July 2010

A review of the literature shows that the soil‐rice plant‐water system of rice culture throughout the world has resulted in subsistence yields of rice grain for a period of 4,000 years. The system has also resulted in the maintenance of nitrogen and organic matter content of the soil, the prevention of soil erosion through the level terrace system of rice culture, the maintenance of soil structure even after purposeful puddling of the soil, the prevention of subsidence of organic soils, and a more rapid release of soil minerals.

These beneficial effects are obtained only when the rice is grown on flooded soil. Dryland rice is comparable to the other small grains in their effects on the soil. Flooding unplanted soil has been shown to be deleterious to the nitrogen supply.

In the Everglades region of Florida, flooded soils alternately planted to rice seem to be the only recourse to prevent a complete disappearance of the muck and peat by the year 2000.

The Federal Government has not considered these factors in its various conservation programs to date.
Using Soil Survey Information for Farm Planning
Authors: Hockensmith R. D.
Published: July 2010

During the first five months of 1952, the views of 79 farm‐planning technicians representing various sections of the country were obtained on the kind of information needed and the manner in which it could best be used in farm planning. Among the major preferences frequently expressed were: Maps of suitable scale, usually 8 inches to the mile for farms and 2 inches to the mile for range land (a 4‐inch field sheet enlarged to 8 inches is satisfactory for farms); precise information on the soil features significant in planning the farm; adequate interpretation in terms of suitability of land for cultivation, the practices and treatments needed, and potential responses to management; and specific information on such items as adapted crops, forage plants, or trees, suitability for irrigation or drainage, suitability for conservation structures, and susceptibility to erosion.

Maps to meet these needs should show significant variation in internal soil features, slope, degree of erosion, and such factors as stoniness, salinity, overflow hazards, or any others that affect potential use of the land or the practices needed for its conservation and improvement. The farm‐planning technician wants specific information on these items, and accurate descriptions for his own use as he works with the farmer. The map that the farmer usually receives, however, shows not only these details, but a grouping of the closely similar mapping units into land‐capability units. The units are further grouped into subclasses and into the eight land‐capability classes. In some places the map received by the farmer shows land‐capability units but not the detailed mapping symbols.

Technical guides for soil and water conservation planning are being organized by land‐capability units, which provide a convenient interpretation of the soil‐survey information. Part of the technical‐guide material for each unit is also prepared in form that is suitable for distribution to the farmer who has that unit on his farm. The land‐capability map of a farm and the appropriate guide sheets together make up a conservation guide for that farm. With the conservation guide as a foundation, and with job sheets for specific practices as the need arises, farmers are encouraged to work out basic conservation plans with their neighbors over a period of time that can vary from a few days to several years. The ideal is to guide them toward becoming conservation farmers who understand the particular capabilities and needs of their land and who apply and believe in the practices that will preserve their soils and keep them productive.
Float‐Valve Pressure Control for Porous‐Plate Apparatus
Authors: Hanks R. J. , Miller E. E. , Tanner C. B.
Published: July 2010

A new type of pressure‐control regulator is described. The performance of this regulator is compared with the mercury tower regulator and with a two‐stage diaphragm regulator. The mercury tower and float‐valve regulators were both sufficiently precise for use with porous‐plate apparatus. The mercury tower was found to be quite inconvenient to use, requiring more experience than either of the other regulators. The float‐valve regulator was found to be easy to use with very little experience but was neither simple nor economical to construct. It was found that the two‐stage diaphragm regulator was not a precise pressure control below about 0.4 atni. However, because it is compact and inexpensive, the two‐stage diaphragm regulator appears to be quite useful where precision is not required.
Equipment for Subsampling and Packing Fragmented Soil Samples for Air and Water Permeability Tests
Authors: Reeve R. C. , Brooks R. H.
Published: July 2010

The permeability ratio, air to water, is used as a measure of the stability of soil structure. Equipment and procedures are described for subsampling, placement in containers, and packing fragmented soil samples for air and water permeability tests. Dropping the soil sample through a 4.75 mm. dia. round‐hole screen into the soil container was found to give a more uniform pack than four other packing methods tested. A reproducible degree of packing, as determined by air permeability determinations, was obtained by dropping the soil‐filled container repeatedly from a height of 2.5 cm. Intrinsic (air) permeability decreased rapidly with degree of soil packing and reached an approximately constant value at about 200 impacts. The relationship between air permeability and bulk density was found to be approximately linear for two soils tested.
The Nature of Phosphate Sorption by Calcium Carbonate
Authors: Cole C. V. , Olsen Sterling R. , Scott C. O.
Published: July 2010

Studies on the nature of phosphate sorption by calcium carbonate indicate that when soluble phosphate fertilizers are added to calcareous soils, the reactions with calcium carbonate consist of rapid monolayer sorption on CaCO3 surfaces and, at high phosphate concentrations in the vicinity of fertilizer particles, the precipitation of dicalcium phosphate, or a compound with similar properties. The initial products of these reactions are characterized by very high specific surfaces and greater phosphorus solubility than the stable hydroxyapatite or fluorapatite. Dynamic equilibrium in calcareous soils involves all of these forms of phosphate. Some of the effects of the ionic environment on solubility of calcium phosphates were calculated and experimentally verified.
Influence of Fertilizers on the Crude Protein Yields of Bromegrass Pasture in the Matanuska Valley
Authors: Laughlin Winston M.
Published: July 2010

Crude protein yields of bromegrass pasture were markedly increased by nitrogen fertilizers. This conclusion is based on field trials in the Matanuska Valley of Alaska during 1949, 1950, and 1951. A split‐plot factorial design was used to compare five rates of nitrogen fertilization, spring versus summer nitrogen applications, and three levels of phosphate‐and‐potash applied in a fixed ratio.

Each increment of nitrogen, including the highest level (128 pounds of nitrogen per acre) produced highly significant increases in protein yields. Greatest production amounted to 636 pounds of crude protein per acre as compared to unfertilized plots which produced only 100 pounds. Sixfold increases were obtained from heavy fertilization which is economically feasible under present conditions.

Significant nitrogen × phosphate‐potash interactions were observed. Early season protein yields are usually increased by phosphate‐potash applications while later clippings are generally not benefitted.

Stage of maturity when grazed also determines crude protein yields which are the greatest during the early flowering stage.
Investigation of Small Grain Response to Various Applications of Nitrogen, Phosphorus, and Potassium on Several Kansas Soils
Authors: Gingrich J. R. , Smith F. W.
Published: July 2010

Four wheat and three oat fertilizer experiments were established at various locations in the eastern half of Kansas for the crop year 1950–51. Objectives of these experiments were to obtain information (1) relative to the best time, rate, and method of applying nitrogenous fertilizers to wheat and oats, and (2) concerning the use of phosphorus and potassium in combination with various rates of nitrogen.

Each experiment consisted of four factorially designed randomized blocks. Rates of nitrogen used were 0, 25, 50, and 100 pounds per acre; rates of available phosphoric acid were 0 and 50 pounds per acre; and rates of potash were 0 and 25 pounds per acre. Chemical analyses of the soils were made. Yield data were analyzed statistically and comparisons were made. Significant yield differences between treatments were obtained for each experiment.

Greatest increases in yield of wheat accompanied the heaviest applications of nitrogen with the single exception of one location which recently had been in alfalfa. The application of both phosphorus and potassium increased the yield of wheat appreciably at this location, most of the increase being due to phosphorus. The application of potash increased the yield appreciably where no ammonium nitrate was supplied.

Significant increases in yield of oats were obtained at each location following the application of 50 pounds per acre of nitrogen. The inclusion of phosphorus and potassium in the fertilizer did not affect oat yields very much.

The time of application of nitrogen generally had little influence on yields of either wheat or oats. From an economical standpoint, application of all the nitrogen at seeding time might be preferable.
The Influence of Soil Aggregate Stabilizers on the Biological Activity of Soils
Authors: Fuller W. H. , Gairaud Catherine
Published: July 2010

The influence of three synthetic polyelectrolytes, hydrolyzed polyacrylonitrile (HPAN), modified vinyl acetate maleic acid compound (VAMA), and a new polymer 212 on the biological activity in six agricultural Arizona soils and quartz sand was investigated. Particular attention was directed to (a) the rate and extent that these materials decompose, (b) the possible toxic or inhibitory effect that these materials may exert on the soil microflora, and (c) the effect that these materials have on the rate and extent of decomposition of a crop residue such as oat straw.

VAMA was found to stimulate biological activity in soil as evidenced by the total cumulative CO2 evolved during 14 days of incubation with soil. HPAN and polymer 212 had little effect on the over‐all biological activity of well‐aerated soil cultures during this period of incubation. This situation appeared to be the same regardless of the presence or absence of oat straw.

The rate of evolution of CO2 measured during intervals of 24 hours, indicated that in soil (a) a certain small portion of VAMA and a very small portion of HPAN and polymer 212 is immediately available to attack by the soil microflora, and (b) when this supply is exhausted the remaining material is so slowly available it has no measurable influence on the cumulative CO2 evolved over a period of five months by the method employed.

The presence of VAMA in sand delayed peak CO2‐evolution depending on the rate of application. This indicated that the soil conditioner had a temporary toxic or inhibitory effect on the microflora in the sand cultures.
The Influence of Certain Fertilizing Materials on the Soil Reaction and Nutrient Level in the Potato Row during the Growing Season
Authors: Dunton E. M. , Hall R. B. , Taylor M. E.
Published: July 2010

This is a continuation of an experiment conducted at the Virginia Truck Experiment Station in 19483 to determine the influence of acid and neutral fertilizers on the soil reaction in the potato row during the growing season. Results from the 1948 study indicate that fertilizers applied in bands in the potato row had a marked influence on lowering the soil reaction, and that the degree of this influence was dependent upon where the sample was taken with respect to the fertilizer bands. The purpose of this study was to determine whether fertilizer materials might differ in their influence on the soil reaction, with some possibly being more effective than others in reducing the pH of soils where there was danger of scab.

A commercial 5‐10‐5 fertilizer was used for treatment 1, and hand mixed materials were used for the other five treatments. In treatment 2, all the nitrogen was derived from NH4NO3, while in treatment 3, it was derived from (NH4)2SO4. In treatments 4 and 5 the nitrogen was derived from NH4NO3, and 50 and 100 pounds of sulfur, respectively, were added per ton of fertilizer. All of the treatments were applied at the rate of 2,000 pounds per acre except treatment 6 where the fertilizer mixture was applied at the rate of 3,000 pounds per acre.

Soil samples were taken 2, 4, 8, and 12 weeks after planting at certain locations around the band. Phosphorus, potassium, pH, nitrate and conductivity tests were run on all samples.

The six fertilizer mixtures markedly lowered the soil reaction in the potato row during the 1949 and 1950 growing seasons. This influence varied with the sampling location or position of the soil sample with respect to the fertilizer bands, with the greatest influence being exerted above the bands. The lowering of the pH was associated with increases in salt concentration in nitrates and in potassium. There was no important differences in the influence of the six different mixtures on the soil acidity except where the soil samples were taken from the fertilizer bands.
The Effects of Different Rates, Times, and Methods of Application of Various Fertilizer Combinations on the Yield and Quality of Hard Red Winter Wheat, 1949–50
Authors: Williams B. C. , Smith F. W.
Published: July 2010

A study was made to determine the effect of nitrogen fertilizer, alone and in combination with phosphate and potash fertilizers, on the yield and quality of wheat; to determine the effect of nitrogen carrier on wheat yield and quality; and to determine the effect of time and method of application of nitrogen fertilizer on yield and quality of wheat.

Yields of wheat were found to be increased at all locations by the use of nitrogen fertilizers. Increasing the rate of nitrogen applied gave varied but similar results. Increases in yields were noted for inclusion of phosphatic fertilizer in the treatment while the inclusion of potash fertilizer had no effect, beneficial or detrimental, on yields of wheat. The later applications of nitrogen fertilizer gave more increase in yield of wheat than did nitrogen fertilizer broadcast before seeding. Only at Manhattan was NH4NO3 significantly superior to CaCN2 in increasing the yields of wheat. At other locations, no differences in effect of type of carrier of nitrogen on yields of wheat were observed.

Test weights of wheat were affected by several treatments at Manhattan and Belleville but not at the other two locations. At Belleville, the resulting effect was a reduction of test weight of the treated plot yield below that of the untreated plot yield, but the effect at Manhattan was in general a reversal of that found at Belleville.

Protein content was increased by several treatments as a result of the use of nitrogen fertilizer alone or in combination with phosphate and/or potash fertilizers. This tendency was most pronounced for the heavier applications of nitrogen fertilizer. The inclusion of potash in the treatment caused an increase in percentage of protein at Belleville but at other locations had no effect on percentage of protein. Phosphorus when included in the treatment decreased the protein percentage. The type of nitrogen carrier had little effect on protein percentage contained in wheat.
Changes in Composition of Irrigated Soils as Related to the Quality of Irrigation Waters
Authors: Thorne D. W. , Thorne J. P.
Published: July 2010

These studies were conducted to determine the effects of field application of waters of different quality on the chemical composition of soils. Soil samples were obtained from paired sites within irrigated and unirrigated soil areas located in 14 different soil locations and representing use of 12 different irrigation waters. The data for irrigation water and soil composition were statistically analyzed for regression and correlation relationships.

The salt content of the soils was found to be closely related to the salt content of the irrigation waters.

The percentages of exchangeable sodium in the soils had significant regressions on sodium percentages, weighted sodium percentages, sodium adsorption ratios and the theoretical equilibrium exchangeable sodium percentages for the irrigation waters included in the study. The regressions of exchangeable sodium percentages on excess sodium percentages of the waters were not significant.

There were significant negative regressions between increase in lime content of the irrigated soils (calcium carbonate content of irrigated soil minus calcium carbonate content of non‐irrigated soil) and the electrical conductance, the chloride content, calcium and magnesium content and sulfate content of the irrigation water. Lime tended to be leached out of soils when the electrical conductance of the irrigation waters exceeded 2 millimhos per cm. and frequently to increase in soils irrigated with waters of lesser salt content.

The data do not indicate that the carbonates and bicarbonates in irrigation waters studied contributed significantly to either the accumulation of carbonates in soils or to increase in exchangeable sodium percentages.
Chemical and Mineralogical Properties of a Brown Podzolic Soil
Authors: Tamura Tsuneo , Swanson C. L. W.
Published: July 2010

Chemical and mineralogical studies were made of the Wethersfield silt loam, a Brown Podzolic soil derived principally from sandstone, siltstone and shale. The clay minerals identified were illite, vermiculite, chlorite, and interstratified montmorillonitechlorite. Illite decreased from the parent material (70%) to the surface (35%) while vermiculite increased from 5% in the parent material to 40% in the surface. The interstratified montmorillonite‐chlorite was positively identified in the B3 and C horizons and composed 15% of the clay fraction. The chlorite, hematite, quartz and feldspars were present in quantities ranging from 5–10% each. Field observations of a compact C horizon capable of supporting a perched water table and a 7% slope facilitating lateral movement of water help to explain the results of the mechanical, chemical, and mineralogical analyses performed in the laboratory.
Properties of the Galva and Moody Series of Northwestern Iowa
Authors: Foth H. D. , Riecken F. F.
Published: July 2010

The purpose of this investigation was to study soil development in relation to loess thickness and annual precipitation in northwestern Iowa. From a study of six profiles located along two traverses, it was concluded that soil properties were related to both loess thickness and annual precipitation on the basis of the amount and distribution of clay, percentage of total nitrogen, base saturation and depth to secondary lime.
The Influence of Soil Properties on the Effectiveness of Synthetic Soil Conditioners
Authors: Laws W. Derby
Published: July 2010

The influence of soil organic matter, soil acidity, free calcium carbonate, soil texture, type of clay mineral, and destruction and re‐forming of stabilized aggregates on the effectiveness of the soil conditioners was studied. Wet‐sieve aggregation data were expressed as mean weight‐diameter and the effectiveness of the conditioner was obtained by subtracting the mean weight‐diameter of the untreated soil from that of the treated soil.

Oxidation of the soil organic matter greatly decreased the effectiveness of the soil conditioner. Adjusting acid soils to pH 6.3 to 7.0 with calcium carbonate increased the effectiveness of the soil conditioner, but the presence of free calcium carbonate in the soil appears to inhibit the effectiveness.

In synthetic soils the effectiveness of the conditioner reached a maximum at 15% clay where acid Cecil clay colloid was used. When base saturated colloids were used, the maximum effectiveness of the conditioner occurred at about 10% clay content. When applied to Texas soils, the conditioner was more effective as an aggregating agent on sandy loam and clay loam soils than on heavy clay soils.
The Effect of Sodium Carboxymethylcellulose on Some Physical Properties of Ohio Soils
Authors: Taylor George S. , Baldridge Paul E.
Published: July 2010

The effect of sodium carboxymethycelluloses (CMC) on soil aggregation, plasticity, moisture equivalent, fifteen‐atmosphere‐percentage, and water permeability was investigated in the laboratory. These compounds contained different degrees of substitution of sodium carboxymethyl groups, ranging from 0.32 to 1.28 substitutions per anhydroglucose unit. In general, increasing the degree of substitution resulted in greater soil aggregation, increased water permeability and larger plastic limits. Varying rates of CMC up to 0.5% concentration also resulted in significant increases in these soil characteristics. None of the compounds had any effect on the moisture equivalent and fifteen‐atmosphere‐percentage. The duration of aggregates stabilized by the 0.70 substitution was found to be much less than those aggregates stabilized by the higher‐substituted types.
Effect of Several Insecticides on Ammonification and Nitrification in Two Neutral Alluvial Soils
Authors: Brown A. L.
Published: July 2010

Columbia fine sandy loam and Yolo loam were incubated in the laboratory at 15% moisture and five rates (0, 0.0005%, 0.005%, 0.05%, and 0.5% active ingredient) of insecticide. The insecticides used were, DDT, aldrin, dieldrin, lindane, heptachlor, and chlordane. All insecticides were applied as wettable powder formulations. Ammonia and nitrate were determined after 15, 30, and 60 days of incubation.

In general, the results seem to indicate that rates of insecticide of 0.05% or greater will inhibit nitrification in some soils. DDT is the least toxic to the nitrifiers of the insecticides studied, while aldrin, dieldrin, and chlordane are the most toxic. Lindane and heptachlor occupy an intermediate toxicity. The significance of the results is discussed.

The rates of insecticide required to produce an effect on nitrification and ammonification are greatly in excess of common rates of application for the materials studied.
Economic Interpretations of Yield Data from a Nitrogen Rate Experiment with Irrigated Grain Sorghum
Authors: Paschal J. L. , Evans C. E.
Published: July 2010

Yield data from a nitrogen rate experiment with grain sorghum on newly developed irrigated land at Tucumcari, N. Mex., were analyzed to ascertain the most profitable rate of nitrogen application for each of four treatment combinations of moisture and plant spacing. The principle of diminishing yield increments is used in calculating the most profitable rate.

As the response of crops to nitrogen is known to vary with soil, season, and other environmental factors, the economic interpretations developed herein are intended to apply only to the conditions of this experiment. With the price of sorghum at $1.12 a bushel and the price of nitrogen at 15 cents a pound, the most profitable rate of nitrogen application ranges from 75 to 152 pounds per acre. The most profitable rate is highest with high moisture (8 irrigations) and thick spacing (43,560 plants per acre) and lowest with low moisture (5 irrigations) and thin spacing (20,028 plants per acre). Moisture level influences the most profitable rate of nitrogen application more than does plant population. When nitrogen is applied at its most profitable rate, the return to nitrogen above its cost with high moisture is $33 for thick and $11 per acre for thin spacing. With low moisture, the return is $15 and $19 per acre for thick and thin spacing, respectively.

The most profitable rate of nitrogen application and necessarily the return to nitrogen above its cost at this rate depend also on the price of sorghum a bushel and the price of nitrogen a pound. Under conditions of constant price and application rate of nitrogen, returns are directly proportional to the price of sorghum. As the price of sorghum rises, the most profitable rate of nitrogen application rises at a decreasing rate. Unless the rate is adjusted with changes in the price of sorghum, loss in return to nitrogen above its cost will result. In most instances, variations of 28 cents a bushel in the price of sorghum above 84 cents affect the most profitable rate of nitrogen application by 25 pounds or less per acre. Exclusive of the direct effect of a change in the price of sorghum on return, failure to apply the most profitable rate when the price changes by $0.28 a bushel results in a loss in returns of $1.00 or less per acre for each moisture‐plant spacing treatment.

With the price of sorghum constant at $1.12 a bushel, moderate changes in the price of nitrogen do not greatly affect either the most profitable rate of application or the return to nitrogen. The rate changes 21 pounds or less with a change of 3 cents a pound in the price of nitrogen for 3 of 4 moisture‐plant spacing treatments. With a change of a cent a pound, return to nitrogen above its cost varies about $1 an acre or less for low‐moisture treatments and less than $2 an acre for high‐moisture treatments.
Soil Organic Matter Levels and Crop Yields in Puerto Rico
Authors: Lugo‐López M. A. , Bonnet J. A. , Hernández‐Medina E. , Landrau P. , Samuels G.
Published: July 2010

No increases in organic‐matter content were observed in some latosols of Puerto Rico with an open porous structure and low fertility level when treated with different quantities of velvetbean green manure, sugarcane trash, and filter‐press cake. Increased yields of corn were obtained only when the soil was treated with velvet bean green manure, probably because of increased nitrogen supply.

Definite increases in organic‐matter content were obtained with the above treatments in heavy‐textured nonlateritic soils of moderate fertility, but unfavorable physical conditions. In this case, increased yields of sugarcane and pineapple were obtained probably due to the favorable effect of increased amounts of organic matter on the physical conditions of the soils. The seven field experiments reported here have been established for relative short periods only, not over 7 years, but some of them are scheduled for long‐time duration.
Effects of Long‐Time Soil Treatments on Some Physical Properties of Several Illinois Soils
Authors: Gingrich Joe R. , Stauffer R. S.
Published: July 2010

Soil cores, 2 inches in diameter and either 1⅜ or 1½ inches in length, were taken from 6 Illinois soil experiment fields in the late summer and fall of 1952 and from 1 field in the early spring of 1953 to study long‐time effects of 3 different soil treatments on permeability to water, moisture percentages at one‐third and at 15 atm. pressures, bulk density, non‐capillary pore space, and the maximum water available for plant growth. All laboratory determinations were made on the undisturbed soil core except the 15 atm. moisture percentages which were made after drying and breaking up the soil core. The treatments studied were manure, limestone, and rock phosphate; no treatment; and crop residues, limestone, rock phosphate, and potash. These systems of management have been followed for approximately 40 years at all locations.

The mean values for several determinations differ greatly for the three treatments but in only a few cases are the differences statistically significant. The manure, limestone, and rock phosphate treatment was usually the most favorable treatment when significant differences were found.

In the design of the experiment fields, replication and crop are confounded. The only mean square for testing treatments was the crop x treatment interaction which was usually large and had only 4 degrees of freedom. This may be the reason why more differences due to treatment were not shown to be significant.
Influence of Sample Pretreatment on Soil Moisture Retention
Authors: Elrick D. E. , Tanner C. B.
Published: July 2010

The effect of sample pretreatment on soil‐moisture retention was measured on eight Wisconsin soils to find the moisture tension range in which undisrupted soil samples are necessary to represent the moisture relations of field soils. The moisture retention of samples with pretreatments either of 2‐mm. sieving or puddling was compared with the retention of undisrupted cores over the moisture tension range of 0.01 to 15 atm.

In general, the moisture retention of sieved samples of the medium textured soils studied was increased over core samples at tensions less than 0.4 atm. There was no general relationship in the tension range of 0.4 to 1.0 atm. because of the irregular nature of the release curves of individual soils. Sieving decreased moisture retention about 1 part in 10 at tensions greater than 1.0 atm. Thus sieved samples of the medium textured soils studied can be used to approximate undisrupted soils in the high tension range with a relative error of 10%. Core samples should be used at tensions less than 1.0 atm. to avoid relative errors greater than 10% (up to 30%).

Puddled samples retained considerably more water than cores in the tension range from 0.1 to 2.0 atm. although they differed little from core samples at tensions less than 0.05 to 0.1 atm. and greater than 5.0 atm. Puddled soils give a better approximation of undisrupted soils than sieved soils at tensions between 5 and 15 atm.
Radioactive Studies with P32 in Tropical Soils and Crops of Puerto Rico
Authors: Bonnet J. A. , Riera A. R. , Roldán J.
Published: July 2010

Six experiments—three with sugarcane, one with pineapples, and two with coffee—were completed with P32 to determine what percentage of the phosphorus was taken by the crop from the fertilizer and from the soil respectively. Five different methods of applying the fertilizer to coffee trees were also studied. Superphosphate tagged with P32 was used. The contents of total P and P32 in the crop leaves served as an index for this work.

The data and results obtained in the sixth experiment, the second with coffee, are presented here. A second objective of the experiment was to determine if the leguminous trees, that serve as shade to the coffee trees, absorb part of the phosphorus added as a fertilizer.

The results obtained indicate that coffee trees absorbed a highly significantly greater percentage of the phosphorus from the fertilizer when it was broadcast over the whole or over a 2‐foot wide outer segment of the canopy area than when it was applied in bands, in holes, or over the terrace.

The results indicate also that the leguminous shade trees absorb part of the phosphorus applied to the coffee trees.
“Brown Mud” from the Aluminum Industry as a Soil Liming Material
Authors: Whittaker Colin W. , Armiger W. H. , Chichilo P. P. , Hoffman W. M.
Published: July 2010

“Brown mud” is a siliceous waste product resulting from the extraction of alumina from bauxite. Present production is estimated to exceed half a million tons annually, the disposal of which is a problem in the industry. When dry, the mud contains approximately SiO2 23, CaO 47, Fe2O3 10, TiO2 3.5, Al2O3 5.5, and Na2O 3.6%, and small amounts of other elements.

In a greenhouse study with sweetclover as the indicator crop, using acid Evesboro and Chester soils, the dried brown mud produced yields substantially equal to those obtained with equivalent amounts of other liming materials. Emergence counts and appearance of the crop gave no indications of any toxic effects from the use of the mud. The mud increased soil pH to values that were usually equal to or exceeding those produced by finely divided agricultural limestone and were sometimes equal to those produced with hydrated lime. The calcium concentration in the dried plant material increased as the liming rate increased in about the same manner with the mud as with the other liming materials. As might be expected, the sodium content of the crop tended to be higher where the mud was used. The potassium content of the crop was reduced to a greater extent by the mud than by either hydrated lime or limestone: this effect was probably also due to the sodium content of the mud. The data indicate that the dried mud is a satisfactory liming material.
A Chemical Method for the Rating of Agricultural Limestones Used as Soil Amendments
Authors: Gibaly Hilmy El , Axley J. H.
Published: July 2010

A method for the calibration of the efficiency of both calcitic and dolomitic limestone in relation to their rapidity in correcting acidity in soils is proposed. The procedure is as follows:

Exactly 1.0 gm. of the limestone to be tested is added to 250 ml. of boiling 0.07 N disodium ethylene‐diaminetetraacetate which is contained in a 500‐ml. Erlenmeyer flask connected to a reflux condenser. After refluxing 20 minutes, 10 ml. of ammonia buffer solution (pH 10) is rapidly added. The solution is immediately titrated with 1.0 N magnesium sulphate solution using Eriochrome black T as indicator. The end point is attained when the color of the indicator changes from blue to wine red. Time and rate of heating must be controlled precisely.

Limestone samples are calibrated from these titration results by comparing them to the reaction of calcite under identical conditions.

When the results of this test for 19 commercial limestone samples were compared with the pH change of soil suspensions treated with the same materials, a correlation of 0.96 was obtained. A field test of nine commercial samples showed a correlation with this test of 0.79.
Laboratory, Greenhouse, and Field Studies With Mixed Fertilizers Varying in Water‐Soluble Phosphorus Content and Particle Size
Authors: Owens L. , Lawton K. , Robertson L. S. , Apostolakis C.
Published: July 2010

Greenhouse and field studies were undertaken to evaluate the effect of the water‐soluble phosphorus content and particle size of mixed fertilizers on the availability of fertilizer phosphorus to plants. Supplementary laboratory experiments were conducted to study the behavior of phosphorus in granulated mixed fertilizers under various soil conditions.

The rate at which the water‐soluble fraction of phosphorus moved out of fertilizer granules was rapid, essentially being complete in 48 hours. No important difference in dissolution rate was noted for fertilizers with varying water‐soluble phosphorus contents over the range of 3.3 to 15% moisture. The extent of movement of fertilizer phosphorus away from large granules and the concentration in soil around the phosphate was directly related to the percentage of water‐soluble phosphorus in the fertilizer.

Varying the water‐solubility of phosphate fertilizer having a similar N‐P2O5‐K2O ratio had no significant effect on dry weight yield of wheat plants grown in the greenhouse. The percentage of plant phosphorus derived from fertilizer was markedly influenced by the water‐soluble phosphorus content and the particle size of the mixed fertilizer and soil reaction. Absorption of fertilizer phosphorus by wheat plants from 4–6 mesh granular material was directly proportional to its water soluble phosphorus content. For pulverant fertilizers the phosphorus water solubility had very little effect on the percentage of plant phosphorus derived from fertilizer. At a soil pH of 5.5, wheat absorbed a larger quantity of fertilizer phosphorus than when grown at pH 6.5 or 7.5.

The phosphorus content of field grown sugar beet plants was significantly higher 1 month after planting on plots where fertilizers high in water‐soluble phosphorus were used as compared to those from plots treated with fertilizers low in water‐soluble phosphorus. Two months after planting, values for total phosphorus were similar for plant samples from plots receiving fertilizers either high or low in water‐soluble phosphorus. Although the yield response to phosphorus was highly significant, there were no significant differences in sugar beet yields between fertilizer treatments.
Crop Rotations and Soil Nitrogen
Authors: Haynes J. L. , Thatcher L. E.
Published: July 2010

Evidence from a 39‐year record of corn yield from trop rotation experiments on Wooster silt loam soil fails to show long‐term cumulative trend effects of commonly‐used corn belt rotations on soil productivity. Yield levels characteristic of a given rotation were quickly reached with no pronounced trends thereafter. In general, yield level was associated with soil nitrogen level. Long‐term downward trends in apparent soil productivity level were observed under conditions of continuous cropping to corn and under conditions of severe erosion.
Effects of Cultivation on Some Soil Physical Properties and on Potato and Corn Yields
Authors: Blake G. R. , Aldrich R. J.
Published: July 2010

Field corn and potatoes were cultivated 0 to 3 times and 0 to 5 or 7, respectively for 3 years, to determine the best level of cultivation for each crop. Weeds were controlled with chemicals so that the noncultivated plots were neither hoed nor scraped. One cultivation for corn or one or two for potatoes gave virtually as high yields as any greater number. All amounts of cultivation gave higher yields than none at all.

Excessive cultivation resulted in lower air space and aggregation and higher bulk density though these differences were not always significant. Cultivation and sprayer traffic was shown to result in a generally lower potassium content of potato leaves. This is believed related to the lower air space found under these conditions.

Soil moisture tensions show that some of the benefit from cultivation may result from conservation of moisture. They also indicate that while weeds compete for moisture, this alone does not account for higher yields where weeds are controlled by cultivation.
A Tube Containing Gypsum Blocks for Following Moisture Changes in Undisturbed Soil
Authors: Abd‐El‐Samie Ahmed G. , Marsh Albert W.
Published: July 2010

The increased use of gypsum blocks for following soil moisture changes and scheduling irrigations has stimulated efforts to improve their installation, performance, and removal from the field. Gypsum blocks were cast in tubes at 6‐inch intervals to simulate the usual practice of installing a series of blocks through the root zone. Three types of block‐in‐tube constructions were described and results from their use reported. The results indicate that blocks perform satisfactorily when cast in tubes.

The tubes can be quickly installed in an auger or king tube hole, assuring intimate contact with undisturbed soil and roots. The problems associated with back‐fill are eliminated and removal at the close of the season is easy. The length of time following installation for equilibrium with the surrounding soil to be reached is reduced.
Rock Phosphate Availability as Influenced by Soil pH
Authors: Ellis Roscoe , Quader M. A. , Truog Emil
Published: July 2010

The influence of the pH of the culture medium on the availability of rock phosphate to oats was investigated by means of two sets of pot cultures. In one set, quartz sand containing 1% of montmorillonite clay served as the culture medium. Samples of the clay, previously saturated with H+, were treated with varying amounts of Ca(OH)2 to provide a series of samples having pH values of 4.9, 5.5, 6.2, 6.7, and 7.4, respectively. Addition of these clays to quartz cultures imparted their respective pH's to the cultures. In one series, rock phosphate served as a source of phosphorus, and in a second, superphosphate served similarly. All other nutrients were supplied in soluble forms. The yield with rock phosphate was highest at pH 5.5. With superphosphate yields were good throughout and approximately double those with rock phosphate. A soil pH of 6.0 or lower appears to be necessary for satisfactory utilization of rock phosphate.

In a second set of pot cultures, Spencer silt loam subsoil of pH 5.1 and very low in organic matter and available phosphorus served as the culture medium. Other nutrients than phosphorus were supplied in available forms. When rock phosphate was applied 1 month prior to liming to pH 7, the oats grew much better and absorbed much more phosphorus than when the order of applications was reversed, showing that strongly acid soils act on rock phosphate rather rapidly, and that for rock phosphate to be effective acidity is needed. Thus, it is advisable to apply rock phosphate a year or more in advance of liming.
Brunizem‐Gray Brown Podzolic Soil Biosequences
Authors: White Everett M. , Riecken F. F.
Published: July 2010

A study was made of two biosequences composed of Brunizem and Gray Brown Podzolic soils and their forested intergrades to determine some of the properties of the intergrades and their relationship to recognized great soil groups. The morphology of the intergrade soils is intermediate to that of the associated Brunizems and Gray Brown Podzolic soils. Laboratory data indicate that, genetically, the intergrade soils are related more closely to the Gray Brown Podzolic soils than to the Brunizems.