bluuebunny/crossref_metadata_2025 huggingface dataset:
Soxhlet Extraction of Simazine from Soils
Authors: Adams Russell S.
Published: July 2010

Simazine was quantitatively extracted from soils and clays in 2 to 24 hours using 95% ethanol as a solvent in a Soxhlet extractor. Absorption of ultraviolet light by the extracts was measured at 220 and 240 m µ and quantities of simazine and hydroxysimazine calculated from simultaneous equations. Plotting recovery of simazine vs. time of extraction as a first‐order reaction gave straight lines that varied in slope with each soil or clay sample. From the slope of the line a release constant (KRC) was calculated. Relating these constants to clay and organic matter contents and the cation‐exchange capacity (CEC) of the soils indicated that the ease of extraction was inversely related to the clay contents and CEC. However, bioassays demonstrated that the organic matter contents of the soils exerted the greatest influence upon the bioactivity of simazine in these soils. The organic matter‐simazine complex was presumed to be soluble in the alcohol and the KRC values were considered to represent a measure of the affinity of the clay for simazine.
Characterization of Mineralizable Nitrogen in Soils
Authors: Keeney D. R. , Bremner J. M.
Published: July 2010

A study of the changes in total N, fixed ammonium N, and hydrolyzable and nonhydrolyzable forms of N that occurred when soils were incubated under conditions which promoted mineralization of soil N showed that prolonged incubation led to a marked decrease in all forms of N determined excepting fixed ammonium N and indicated that native fixed ammonium is practically unavailable to soil microorganisms. It also showed that there are marked differences among soils with regard to the nature of the N that is most readily mineralized and made available for plant growth and indicated that any chemical method of obtaining an index of soil N availability based solely on determination of a hydrolyzable or nonhydrolyzable form of soil N will prove unsatisfactory.
The Alkaline Permanganate Oxidation of Danish Illuvial Organic Matter
Authors: Hansen E. H. , Schnitzer M.
Published: July 2010

Organic matter extracted from the Bh horizon of a Danish Podzol was oxidized with alkaline permanganate. Steamdistillation of the oxidation product yielded 1.6% aliphatic monocarboxylic acids (on the basis of the original organic matter). The acids were identified by gas chromatography. Acetic acid represented 73% of these acids, while the remaining 27% consisted of n‐ and iso‐acids, containing up to 8C‐atoms. The oxidation product was extracted with organic solvents and the extracts methylated and then vacuum‐distilled. By means of gas chromatography all of the 12 possible benzene carboxylic acids except benzoic acid were identified, accounting for 1.4% of the original organic matter.

The possible significance of the acids identified with regard to the chemical structure of the original organic matter preparation is discussed.
On the Mechanism of Phosphorus‐Zinc Interaction in Corn Nutrition
Authors: Stukenholtz D. D. , Olsen R. J. , Gogan Gerald , Olson R. A.
Published: July 2010

Studies were carried out in the greenhouse and field to elaborate the mechanism of P‐Zn interaction in the nutrition of corn (Zea mays L.). From this work depressive action of P on Zn uptake of corn appears to be largely physiological in nature, expressed at root surfaces and/or in root cells, and is not chemical inactivation of Zn by P in soil. Translocation of Zn from roots to tops is inhibited by elevated P concentration, with resulting sharp reduction in Zn concentration of nodal and internodal tissues. No clearly definable P/Zn ratio in tissue was found above which yield restriction could be predicted. Corn seems to tolerate high concentrations of P in its tissues provided some modest quantity of Zn is present.

Other elements counteract somewhat the damaging effects of P. Concurrently placed N promotes Zn uptake at the same time that it benefits P utilization. Increased level of native or applied K reduces the depressive effects of P on Zn.
Response of Corn (Zea mays L.) to Zinc, as Affected by Placement and Nitrogen Source
Authors: Giordano P. M. , Mortvedt J. J. , Papendick R. I.
Published: July 2010

Dry matter production and uptake of Zn, N, and P by corn grown in greenhouse pots were higher with (NH4)2SO4 than with anhydrous NH3 or CO(NH2)2, whether ZnSO4 was mixed, spotplaced, or not applied. These results are largely explained by the lower soil pH associated with application of (NH4)2SO4 and hence, the increased availability of indigenous and applied Zn. Yields were lower when Zn was mixed, but higher when Zn was omitted or spot‐placed 4 weeks prior, as compared to treatment just prior to planting. In general, Zn and N uptake varied directly with yield and inversely with P uptake, except where growth was extremely poor due to severe Zn deficiency.
Color and Growth of Douglas‐Fir Christmas Trees as Affected by Fertilizer Application
Authors: Turner Darrell O.
Published: July 2010

Eight fertilizer treatments of varying amounts of N, P, K, S, and Mg were applied to a chlorotic stand of 15‐year‐old Douglasfir (Pseudotsuga menziesii) Christmas trees grown upon glacial moraine soil in the Puget Sound basin. Color ratings, growth measurements, and foliar analyses data were collected during two growing seasons.

Fertilizer N rates from 0.125 to 1.0 lb/tree improved color the first season without influencing growth. All rates of N improved color the second season, but only the 0.125 N level produced an acceptable rate of growth. Rates of N above 0.125 lb/tree overstimu'ated growth for Christmas tree production.

Color was correlated to total‐N levels in the foliage; trees with dark green foliage had high total‐N contents.

Treatment with P and K in the absence of N did not improve color or increase growth. Treatment with N, P, K, S, and Mg gave the darkest green color and highest total‐N level the first year, but color faded and total‐N content declined in the second season.

Cones were formed only on trees which received the N‐P‐K and N‐P‐K‐S‐Mg treatments.
Recovery of Fertilizer Nitrogen Under Field Conditions Using Nitrogen‐15
Authors: Carter J. N. , Bennett O. L. , Pearson R. W.
Published: July 2010

An experiment was conducted under field conditions to study the movement and recovery of N15‐enriched nitrogen fertilizer added to soil in the forms of NaNO3 and (NH4)2SO4. The plots consisted of the soil mass inside cylinders 30 or 60 cm in diameter, which were pressed into the soil to a depth of 45–60 cm. These plots were either seeded to sudangrass (sorghum sudanense) or left uncropped. The plant tops, roots, and the soil, by 15‐cm layers, were analyzed for total N and excess N15 content.

Recovery of added N15 from the 32 plots ranged between 96.3 and 101.8%, and averaged 99.0%. There was no significant difference in recovery of the fertilizer N due to the percent of excess N15 in the fertilizer, size of plot, exposure to natural rainfall, cropping, N source, or the time of application of the fertilizer. Wide variation in recovery of excess N15 occurred with core sampling and it was found necessary to remove, weigh, mix and subsample the entire soil mass from within the rims. The small amounts of unrecovered N were probably due to procedural errors in the field and laboratory, and leaching and root growth beyond the sampling zone. There was no indication of any N loss in the gaseous form.

The fate of applied fertilizer N was followed under field conditions using N15‐enriched nitrogen fertilizer applied to the soil in situ enclosed by large steel cylinders. Total recovery of the fertilizer N from these experiments after 8 weeks ranged from 88 to 96%, but dropped as low as 77% after 10 months. Recovery of the fertilizer N was greater from an ammonium source than from nitrate. Retter recovery of fertilizer was obtained when the plots were cropped to sudangrass rather than left fallow. Doubling the rate of application of the fertilizer N from 336 to 672 kg/ha did not affect percent of total recovery. The 4 to 12% of fertilizer N unrecovered after 8 weeks appears to be due to a loss in the gaseous form, since special precautions were taken to restrict leaching and to eliminate errors in sampling and analysis.
The Ureolytic Microflora in a Black Spruce (Picea mariana Mill.) Humus
Authors: Roberge M. R. , Knowles R.
Published: July 2010

The total and the ureolytic microflora in black spruce humus from an untreated plot and from a plot fertilized with 450 kg urea‐N per ha (400 lb N per acre) 2 years before sampling was studied using incubation tests. Following the addition of 3,500 ppm of urea‐N in the laboratory the total numbers of bacteria and fungi increased on the average by 332 and 9.6%, respectively, and the numbers of ureolytic bacteria and fungi increased by 359 and 18.5%, respectively. The percentages of ureolytic bacteria and fungi both increased by only 5, indicating that the increase in population was not made up of specifically ureolytic organisms. No significant population changes occurred after 3 days of incubation, when urea hydrolysis was complete.

The application of urea in the laboratory to humus from a plot treated with urea two years before sampling brought about population changes which roughly paralleled those found in humus from the untreated plot.

In any particular humus layer, the population increase occurring in the field during the two years after urea application was observed to be in general greater than that occurring during the 42 days after the application of urea to the same humus layer in the laboratory.
Organic Phosphorus in Calcareous Colorado Soils
Authors: Greb B. W. , Olsen S. R.
Published: July 2010

Organic P in calcareous soils was determined by a modified 4N HCl‐0.5N NaOH extraction procedure. Organic P averaged 23% of the total P in soils from 23 locations in Colorado, 26% for 3 irrigated rotation soils of 4 rotations each, and 27% in 4 virgin soils. Organic C, N, and P were highly correlated for all soil groups tested. Carbon‐to‐phosphorus ratios of 95:1, 72:1, and 128:1 were obtained for the Colorado, rotation, and virgin soils, respectively. Alfalfa (Medicago sativa) and manure in in rotations increased the level of organic C, N, and P, and also the C/P and N/P ratios when compared with continuous row cropping without organic residues. Alfalfa was more effective than manure in maintaining organic C, N, and P. Nonvirgin soil contained less organic P, much less organic C and N, and lower C/P and N/P ratios than virgin soil. Organic P mineralized at an average of 3.6 ppm P for 13 Colorado soils when incubated for 21 days at 35C.
Some Till‐Derived Chernozem Soils in Eastern North Dakota: II. Mineralogy, Micromorphology, and Development
Authors: Redmond C. E. , Whiteside E. P.
Published: July 2010

Mineralogical and micromorphological studies of three soil profiles representative of the Forman, Barnes, and an Intermediate soil group (described in the first paper of this series) are presented. The mineralogy is used to evaluate the uniformity of the original materials of each soil. Calculations of the net changes in sand, silt, clay, CaCO3 equivalent, organic matter and volume of two of the profiles and the individual horizons in each are presented and their int rpretations are discussed. There is need for improved sampling techniques and better measures of the natural variability of the materials.
Effect of Dilution on Calcium and Potassium Contents of Soil Solutions
Authors: Khasawneh F. E. , Adams Fred
Published: July 2010

The effect of dilution on the composition of a soil solution of Magnolia sandy clay loam subsoil was investigated. Samples of a Ca‐ and K‐saturated soil as well as samples of a soil saturated with K and mixed with CaCl2 were equilibrated with water in various soil‐water ratios. Equilibrium solutions were separated and analyzed for Ca and K. Dilution increased the total amount of solution electrolytes with a concurrent change in the relative amount of each of the solution cations. The following equation was derived from Langmuir's isotherm to describe the desorption of neutral salts from soil surfaces: S = St V/(a + V) where S is the total meq of solution cations in volume V ml, and St and a are constants.

The ratio‐law of Schofield was adequate to describe the change in the relative amount of each cation upon dilution of one soil system, but a correction term was added to the formulation of the ratio‐law in order to describe the data of the other soil system. This formulation of the ratio‐law is given as
urn:x-wiley:03615995:saj2sssaj196703615995003100020010x:equation:saj2sssaj196703615995003100020010x-math-0001 where m is the number of solution mmoles, V is the solution volume in ml, and k and h are constants. The two foregoing equations provide the means for predicting the composition of a soil solution upon dilution.
Characterization of Fixed Strontium in Sesquioxide Gel‐Kaolinite Clay Systems
Authors: Frere M. H. , Champion D. F.
Published: July 2010

“Fixed” Sr is defined by the amount of radioactive Sr remaining with the solid phase after three extractions with 1N Sr(NO3)2. The amount of Sr fixed in a soil‐water suspension increases with time in a manner characteristic of a slow diffusion process. Experiments with Fe or Al gel‐kaolinite clay suspensions showed a similar behavior. The amount of fixation in gel‐clay suspensions increased with pH to a level of about 6% of the adsorbed Sr at pH 8. The reaction was insensitive to the amount of gel and decreased with the aging of the gel‐clay suspension. The level of fixation in the gel‐clay suspensions was considerably less than observed in soils, particularly when acid pH's and aged systems are considered. Several exploratory experhaents indicate a silicate interface may be important in the fixation mechanism.
Some Effects of Moisture on Denitrification in Acid and Alkaline Soils
Authors: Mahendrappa M. K. , Smith R. L.
Published: July 2010

Samples of two acid and two alkaline soils were studied to observe the effect of various moisture levels in open or closed systems on denitrification of added nitrate. Under anaerobic conditions, each soil appeared to have specific moisture requirements for maximum denitrification rate. Under fully anaerobic conditions, an increase in moisture content to only 10% above field capacity markedly decreased the time required for complete denitrification as defined by N2 production but had little effect on the disappearance of the nitrate. Further increases in moisture content reversed the trend and increased the time needed for complete denitrification to take place.

It is proposed that some of the moisture effects are attributable to the distribution of organisms and/or N compounds. Part of the effect, however, also may be due to a dilution effect on toxic products produced. Indirect evidence indicated that an intermediate compound or compounds may have been produced but not detected in the analysis scheme.
The Effect of Moisture on Fertilizer Nitrogen Immoblization in Grasslands
Authors: Power J. F.
Published: July 2010

The fate of 500 kg of fertilizer N per ha applied to Bromus inermis L. was followed for 2 years for various moisture levels and times of application. Analysis of the plots at the end of 2 years of irrigation (with no leaching) showed that about 40% of the fertilizer N was contained in grass tops and 25 to 35% in roots, while 5 to 10% was in the soil in mineral form and 20% was not accounted for. For dryland plots this distribution was 25%, 10 to 25%, 25 to 65% and 0 to 20%, respectively. The primary effect of increased water was to hasten plant absorption of fertilizer N. Fertilizer N losses were not affected by moisture supply, thus with proper fertilization it may be possible to maintain a constant pool of available N in grassland soils of semiarid regions without experiencing undue losses. Maximum growth could then be achieved whenever water is available by eliminating N as a growth‐limiting factor.

Weekly applications of 17 kg of fertilizer N in fallow plots resulted in about 175% of the fertilizer N being accounted for, but when the fallow plots received all the fertilizer N in the spring only 50 to 60% was accounted for. These differences may have been caused by differences in rates of mineralization and denitrification. Soil NO3‐N levels on fertilized dryland often rose during periods of drought. Soil NO3‐N levels in fertilized irrigated plots declined with time. Unfertilized plots were conistently very low in soil NO3‐N, regardless of time or water supply.
Free Iron and Coloration in Certain Well‐Drained Coastal Plain Soils in Relation to Their Other Properties and Classification
Authors: Soileau J. M. , McCracken R. J.
Published: July 2010

Physical, chemical, and mineralogical studies were conducted on several well‐drained, moderately fine‐textured North Carolina Coastal Plain soils (primarily Orangeburg and Norfolk series) belonging to the Typic Hapludult subgroup and ranging in B horizon coloration from yellow to yellowish red. Results indicated that geomorphic landscape position and associated relative soil age influence some properties more than does coloration of the B horizon. It appears that to much emphasis has been placed on the hue of the B horizon as a series differentiating criterion in these reddish‐ and yellowish‐hued coastal plain soils.

Except for horizons containing plinthite or intense iron mottling, nearly all of the free iron oxide in the soils investigated occurred in the clay fraction, predominantly in the < 0.2 µ clay. Goethite was the only X‐ray identifiable crystalline iron oxide compound found in clays and other iron‐rich soil fractions. There was no consistent relationship between amounts of free iron oxide and yellow to red Munsell hue × value indices of soil and clay fractions. However, a general trend of increasing free iron oxide content with increasing Munsel chroma was noted in various size fractions of these soils. Free iron and specific surface data indicated that coloration in these soils is not due to the relative thickness of adsorbed iron coatings on the clay surfaces. Heating experiments and infrared studies suggested that the form of the iron oxide (its degree of hydration or neutralization) is the dominant factor in influencing hue of the subsoil in these Coastal Plain soils.
Dayton—A Depositional Planosol, Willamette Valley, Oregon
Authors: Parsons R. B. , Balster C. A.
Published: July 2010

Dayton soil has long been considered a Planosol (Albaqualf) with genetically related horizons developed from Willamette silts. However, a detailed study indicates that Dayton sola overlie six different materials including gravel, silt, and bedrock. The deposits which comprise the A2 and B2 horizons are not coextensive. Therefore, the boundaries between A2, B2, and C horizons represent depositional discontinuities. Soil formation across the discontinuities, under conditions of poor drainage, has produced so'a having morphologic and chemical properties of Planoso's
Gel‐Like Films that May Form at the Air‐Water Interfaces in Soils
Authors: Grossman R. B. , Lynn W. C.
Published: July 2010

When dry soil material is moistened stepwise and then slowly submerged, a film appears on the water surface where it may remain floating for several days as a coherent patch. The film consists of a gel‐like matrix that contains particles ranging upward to sand size. The evidence to date indicates that the film matrix differs little from the < 0.2 µ cay. It is thought that material disaggregated from the surface of the soil material by the disruption of drying and subsequent wetting becomes caught at the air‐water interface and is there spread out by surface tension forces. The possible role of the films in translocation of solids and other aspects of soil development is discussed.
Ionic Exchange Behavior in a Loam Soil as Indicated by Movement of Radio‐Calcium
Authors: Arshad M. A. , Carson J. A.
Published: July 2010

Soil columns were used to study the movement of 45Ca by leaching them with salt solutions of various concentrations and ionic combinations. The results showed that the distribution patterns of radio‐calcium within the soil columns varied with the anionic species as well as with the type of cations of the salt solutions. Exchange and movement of radio‐calcium was higher with sulfate than with chloride salt solutions. The difference is explained on the basis of the differential displacement of calcium from the exchange sites caused by the salts present in soil solution. The data obtained may have significance in understanding the development of solonetzic soils.
Distribution of Total and 0.1 Normal Hydrochloric Acid‐Extractable Zinc in Hawaiian Soil Profiles
Authors: Kanehiro Yoshinori , Sherman G. Donald
Published: July 2010

In most Hawaiian soil profiles, the highest concentrations of 0.1N HCl‐extractable Zn were found in the surface horizons. There was a general decrease in extractable Zn with soil depth. Extractable Zn was found to range from 0.1 to 17.9 ppm.

The concentration of total Zn appeared to be less dependent on depth than was acid‐extractable Zn. In some profiles, where the extractable Zn followed the general pattern of decreasing with soil depth, the total Zn content remained the same or even slightly ncreased with depth. Total Zn was found to range from 51 to 288 ppm.

There was a highly significant correlation between total and extractable Zn. This correlation was especially evident in the relatively youthful and unweathered soils but not in all oxisols and ultisols. There was no correlation between soil pH and extractable Zn.

The occurrence of Zn‐deficient plants was better correlated with acid‐extractable soil Zn values than with total soil Zn values. Most soils on which Zn deficiency is found are oxisols or ultiscls that have undergone intensive weathering or have had their subsoils exposed. In a greenhouse experiment, corn (Zea Mays L. plants grown in an ultisol sampled from an eroded site showed more pronounced Zn‐deficiency symptoms and lower vegetative yields than those grown in an adjacent surface‐intact soil.
Yield Response of Spring Wheat and Barley to Nitrogen Fertilizer in Relation to Soil and Climatic Factors
Authors: Young R. A. , Ozbun J. L. , Bauer A. , Vasey E. H.
Published: July 2010

The relationship between yield response of spring wheat (Triticum (aestivum L.)sp.) and barley (Hordeum vulgare L.) to fertilizer N and various soil and climatic factors was determined in a total of 66 field experiments over a 3‐year period using simple and multiple correlation and regression.

Measured variables included precipitation and air temperature from seeding to harvest; available soil moisture and NH4‐N plus NO3‐N at seeding to a depth of 152 cm; N extracted with alkaline permanganate and total N to 61 cm; organic matter to 30.5 cm; and NH4‐N plus NO3‐N accumulated during 2 weeks incubation at 35C from samples retained field moist, frozen, and air‐dried before incubation, to 61 cm.

The factors that showed significant relationships with yield response to nitrogen fertilizer were (i) stored available soil moisture at seeding to 122 cm or a dry zone, (ii) stored NO3‐N to 61 cm at seeding, (iii) precipitation from seeding to 5 days before harvest and (iv) degree days above 21C from 5 to 60 days before harvest.

Using stored NO3‐N, stored available moisture, average growing‐season precipitation and temperature, and a calculated value of 8.40 kg of fertilizer N/ha to produce a yield response of 1 quintal, predicted N fertilizer rates were within 11.2 kg/ha of actual amounts required in over 50% and within 22.4 kg in 89% of the experiments.
Chemical Availability of Native and Applied Phosphorus in Soils and their Textural Fractions
Authors: Halstead R. L.
Published: July 2010

In a study of several Canadian soils, the Al‐P fraction (Chang and Jackson, 4) was correlated with the percent yield [(yield without P × 100)/yield with P] of oats grown in the greenhouse and with estimates of available P (NaHCO3‐soluble). Although Fe‐P was related to NaHCO3‐soluble P and Ca‐P to acid‐soluble P (Troug, 20), neither the Fe‐ or Ca‐P fraction was related to yield. NH4Cl‐soluble P, however, was correlated with both percent yield and percent P uptake. The four P fractions (NH4Cl‐soluble, Al, Fe, and Ca) comprised a major part (62 to 92%) of the total inorganic P in the soils. Ca‐P was the main form in all but the Podzols, in which Fe‐P predominated.

Organic P, Al‐P, Fe‐P, and NaHCO3‐soluble P increased with decreasing particle size, whereas Ca‐P, total inorganic P, and acid‐soluble P (Truog) increased with decreasing particle size in the Podzols but not in the other soils. When the P in the total amount of a given particle‐size fraction present in the soil (F value) was considered, it was found that the coarser fractions contributed a relatively large proportion of the P in some of the soils. In five out of seven comparisons a major part (>50%) of the total inorganic P, Ca‐P, and Al‐P was associated with the coarser silt and sand, whereas Fe‐P and organic P were associated with the fine silt and clay. The significant relation of F values for Al‐P of the clay to percent yield and percent P uptake provided further evidence of the importance of Al‐P as a source of P for plants. Other relationships between yield parameters and F values for NH4Cl‐soluble P and Ca‐P of the clay indicate that the clay may be a primary source of plant P.

In incubation studies with soils and textural fractions, a major part of the added P was recovered in the Al‐ and Fe‐P forms. Al‐P was the primary form of recovery except in the fine silt and clay fractions of the Podzol soils where Fe‐P predominated.
Effect of Black Granular Mulch on Soil Temperature, Water Content, and Crusting
Authors: Qashu Hasan K. , Evans D. D.
Published: July 2010

The use of black granular coke material as a mulch and its influence on soil temperature, evaporation, and soil crusting were studied under laboratory conditions and in the field. Higher soil temperatures were measured under mulch as compared to the control. Thermal regimes in a sand tank differed with treatment as to mulch strip width and geometry for dry sand. Evaporation suppression from wet sand was proportional to the relative area covered by mulch.

Application of mulch on ridges in the field resulted in the following: (i) increase in daytime soil temperatures in the top 30 cm of soil, (ii) higher water content in the top 3 cm of soil under the mulch as compared to the control, and (iii) a friable soil crust under mulch as compared with a massive rigid crust in the control.
Inorganic Nitrogen Transformations through the Oxidation and Reduction of Sulfur Compounds
Authors: Chao Tyng Tsair
Published: July 2010

Inorganic nitrogen transformations result from the chemical oxidation and reduction of sulfur compounds. In the reduction of nitrate by NaHS, Na2S2O4 in both acidic and basic solutions, nitrite was not obtained suggesting that it may not be one of the major intermediate products in such reductions. Hydroxylamine was one of the intermediate products in the reduction of nitrite in acidic solution. Ammonia was not produced appreciably in the reduction of nitrate and nitrite. Due to the interference of hydroxylamine with Nessler reagent, ammonium ion formed in the reduction of hydroxylamine by sulfur compounds could not be measured quantitatively. However, a larger amount of ammonium‐N in the reduction of hydroxylamine by H2SO3 was observed. Nitrite, hydroxylammonium, and ammonium ions were never found in the solution in large quantities presumably due to (i) the formation of H2N2O2 which is unstable with respect to the formation of N2O (1,2), (ii) the interaction between nitrite and hydroxylammonium ions in the formation of N2O (1,3), and (iii) the oxidation of hydroxylamine or hydrazine by sulfur compounds to form N2O and N2.
Exchangeable Soil Potassium as Influenced by Seasonal Cropping and Potassium Added in Crop Residues
Authors: Grimes Donald W. , Hanway John J.
Published: July 2010

Detailed sampling of soils and crops from three long‐term field experiments permitted evaluation of the seasonal depletion of exchangeable soil K and the influence of K added as crop residue. Exchangeable soil K was markedly reduced during the growing season by a growing crop. For corn (Zea mays L.), the regression of the decrease (spring to fall) in exchangeable K (pp2m) on the initial (spring) level of exchangeable K was characterized by a quadratic relationship, Ŷ = −23.5 + 0.62X − 0.00072X2 (r2 = 0.78**). Increases in the exchangeable K from fall to spring were directly related to K additions in crop residues. Within a single crop rotation, the exchangeable K increased as a result of K additions from corn residues and declined when meadow was grown. When maintained in a field moist condition before the determination of exchangeable K, reduced levels of exchangeable K resulting from cropping were not restored by release of non‐exchangeable K. When the exchangeable K was reduced to a very low level, however, nonexchangeable forms of K were released to the exchangeable form to maintain a “minimal” level of exchangeable K.
Diameter Growth of Loblolly Pine Related to Available Soil Moisture and Rate of Soil Moisture Loss
Authors: Moehring D. M. , Ralston C. W.
Published: July 2010

In six sawtimber stands in northeastern Louisiana, loblolly pine (Pinus taeda L.) diameter growth was related to the amount of and weekly rate of change in available soil moisture from June through August. Regardless of the amount of moisture available during the summer, growth was curtailed when soil moisture loss was rapid. Consequently, the soil moisture content at which tree growth ceased was highly variable.
In Situ Measurement of Soil Salinity with a Sensor
Authors: Oster J. D. , Ingvalson R. D.
Published: July 2010

The electrical conductivity (EC) of the soil solution was measured in situ in a soil‐plant system during three irrigation cycles. The salinity sensors used to make the measurements responded to changes in EC resulting from water uptake by the plant and salt movement in the soil profile by convection of salt in soil water. The accuracy of the measurements was estimated to be ± 0.5 mmho/cm throughout the irrigation cycles.
Relations Between Acidic Aluminum and Soil pH, Clay and Organic Matter
Authors: Pionke H. B. , Corey R. B.
Published: July 2010

The relationships of two measures of acidic Al contained in soil, namely KCl‐exchangeable Al and nonexchangeable acidic Al (pH 4.8N NH4OAc extractable Al minus KCl‐exchangeable Al) with soil pH, clay, and organic matter content were evaluated statistically. Exchangeable Al concentrations were observed to be primarily related to pH. The nonexchangeable acidic Al was found to be significantly correlated with pH, clay, and organic matter content at the 1% level. However, nonexchangeable acidic Al correlated best with the organic matter which would imply the existence of aluminum‐organic matter complexes in soil. A plot of nonexchangeable acidic Al with soil pH as determined in 1N KCl revealed an apparent maximum at a pH of approximately 4.1. These various interrelationships are combined into a proposed reaction scheme relating the various Al forms postulated to exist in soil.
Soil and Plant Silicon and Silicate Response by Sugar Cane
Authors: Fox R. L. , Silva J. A. , Younge O. R. , Plucknett D. L. , Sherman G. D.
Published: July 2010

Calcium silicate slag increased sugar yields 12 tons/hectare in a field where phosphate extractable soil silicon and trichloroacetic acid (TCA) extractable silicon of sugar cane (Saccharum officinarum) leaf sheaths were about 20 ppm. Large amounts of P or lime did not alleviate leaf freckle whereas slag did so to a marked degree. Acid solutions of phosphate, sulfate, acetate, and water can be used successfully as extractants for soil silicon. The general order for extractable silicon from soils developed on basalt and alluvium was: Humic Ferruginous Latosol < Humic Latosol < Low Humic Latosol < Dark Magnesium clay. This is also the order of decreasing weathering for these soils as indicated by total soil silicon and occurrence of secondary minerals. Leaf sheath silicon (TCA extractable) was especially well correlated with log extractable soil silicon (r = 0.97 for water extraction). Irrigation waters may contain much silicon and contribute greatly to the supply of extractable soil silicon and to plant silicon.
The Lower Boundary of Selected Mollisols
Authors: Douglas C. L. , Fehrenbacher J. B. , Ray B. W.
Published: July 2010

Thicknesses of three Mollisols (Tama, Elburn, and Drummer series), developed from Wisconsinan‐age material in a toposequence in Central Illinois, were considerably greater (18 to 68 cm) when their lower boundaries were determined by the depth of rooting of native perennial big bluestem (Andropogon gerardi) than when determined by the lower limit of the solum. A combination of four criteria—structural development, significant clay accumulation, significant clay films, and the presence of completely unleached material—probably gave the best measure of solum thickness of these soils. However, evidence of some clay movement below the solums and the greater depth of rooting of native perennial grass, and also of such crops as corn (zea mays L.), suggests that material beneath the solum is important in the behavior, definition, and classification of many of these kinds of soils in the north‐central region of the U.S.
Phosphate Determination in Presence of Polyethylene Glycols
Authors: Segall E. , Mokady R. S.
Published: July 2010

Polyethylene glycols, used in order to equilibrate aqueous solutions with unsaturated soils, interfere with colorimetric determinations of phosphate. The interference in the molybdovanadate method may be overcome by working in 25% 2‐butanone, and comparing with standards containing roughly the same concentration of the polymer as the samples.
Micromorphological Study of Soil Crusts
Authors: Evans D. D. , Buol S. W.
Published: July 2010

Soil crusts were studied by preparing and examining thin sections taken normal to the soil surface. Several photomicrographs of the thin sections are presented which illustrate differences encountered among different soils and among different management practices of the same soil. Some crusts exhibited orientation of particles within the crust while others showed some orientation of the bulk soil mass in certain parts of the crust. A pronounced gradation of texture was evident in certain crusts. This work illustrates the visual evidence obtainable from the use of thin sections in soil crust studies.
Relationship of Total and Hot‐Water Soluble Boron, and Fixation of Added Boron, to Properties of Podzol Soils
Authors: Gupta Umesh C.
Published: July 2010

Total and hot‐water soluble B content of soils ranged from 45 to 124 and 0.38 to 4.67 ppm, respectively. The largest quantities of hot‐water soluble B were recorded in Acadia silty clay loam, Caribou silt loam, and Interval loam to silt loam soil series. Water‐soluble B was comparatively low in soils derived from Permo‐carboniferous rocks.

In general the B content was lowest in coarse‐ and highest in fine‐textured soils. Percent of total B in the hot‐water soluble form varied from 0.44 to 4.69, with the highest percentage occurring in the fine‐textured soils and lowest in the coarse‐textured soils.

Hot‐water soluble B content was higher in “well‐managed” soils than in “neglected” soils. The quantities of such B were positively correlated (significant at p = 0.01) with organic matter and with total B.

Higher amounts of B were fixed by soils after incubation periods of 8 and 12 weeks than after 2 and 4 weeks. A higher percentage of B was fixed in the O'Leary sandy clay loam than in the Dunstaffnage sandy loam soil with all incubation periods. Varying the moisture content of soil from 50 to 100% of the field capacity did not affect the B fixed over a 12‐week period.
Supply of Ca, Sr, Mn, and Zn to Plant Roots Growing in Soil
Authors: Halstead E. H. , Barber S. A. , Warncke D. D. , Bole J. B.
Published: July 2010

The influence of four soils and two transpiration rates on the amounts of Ca, Sr, Mn, and Zn supplied to the root by root interception, mass‐flow and diffusion and on the uptake of these ions by four plant species was investigated in a growth chamber experiment. The relation between the calculated supply to the root by root‐interception plus mass‐flow and the uptake of Ca and Sr was different for each species but was not affected by soil or transpiration rate. The relation between supply of Mn and Zn and uptake was not affected by plant species. The relation of the uptake of Mn was highly correlated with supply by root interception plus mass‐flow over a very wide range of values. The correlation observed between Zn uptake and the supply by root interception plus mass‐flow was lower than for Ca, Sr, or Mn because considerable quantities of Zn also reached the root by diffusion.

Three methods of calculating the quantity of root interception were evaluated by determining the relative degree of correlation between the calculated supply and uptake by the plant. The method which estimates the maximum possible root interception gave the highest correlation. The use of a parameter based on root area was very poorly correlated with uptake.
The Effect of Phosphorus Source on the Movement and Uptake of Band Applied Manganese
Authors: Hossner L. R. , Richards G. E.
Published: July 2010

Plant uptake of band‐applied Mn from a Selma silt loam soil (pH 7.0) was enhanced by blending MnSO4·H2O with each of four P sources in growth chamber tests. The relative value of ammonium polyphosphate (APP), monoammonium phosphate (MAP), diammonium phosphate (DAP), and monocalcium phosphate (MCP) in increasing Mn uptake by soybeans (Glycine max ‘Hawkeye’) was MAP = APP≫MCP = DAP. There was a highly significant correlation between the plant concentration of Mn and P. Plant uptake of Mn was greatest when the pH of the P source was between 2 and 4. The amount of Mn which was absorbed per increment of P varied with the P source. In this experiment APP = MAP > MCP > DAP.

Manganese movement and recovery (measured as exchangeable plus easily reducible) as influenced by P source decreased in the order: APP > MAP > MCP≫DAP. Manganese movement from phosphate mixtures was not detected when the soil pH was greater than 5.8.
Water and Salt Transfer in Soil Resulting from Thermal Gradients
Authors: Weeks L. V. , Richards S. J. , Letey J.
Published: July 2010

Rate equations developed from the theory of thermodynamics of irreversible processes were used to analyze water transfer induced by thermal gradients along a sealed cylindrical horizontal column of Pachappa soil. Functional relations to calculate values of coefficients in the flow equations were determined from experimental data which were obtained during steady‐state flow conditions. The relations were used to compute values of coefficients in order to calculate flow rates past selected positions along the column at various times during transient flow periods. Suction head (h) values were maintained in a range that could be measured with tensiometers which were located at three positions along the column. Liquid water transfer toward the warm end was assumed to be due to an induced suction head gradient. This transfer was confirmed by sectioning the column at the end of the experiment and measuring the concentrations of Na+ and Cl‐ and the EC of saturation extracts prepared from the sections.
Platinum Microelectrode Poisoning Factors
Authors: Rickman Ron W. , Letey J. , Aubertin G. M. , Stolzy L. H.
Published: July 2010

The oxide coating that occurs on platinum electrodes would be expected to influence oxygen diffusion rate (ODR) measurements on the basis of electro‐chemistry literature. However, no consistent influence of condition of electrode oxidation on ODR measurement in clay suspension was found by the authors. The current density on electrodes in clay suspensions was suspected of being below that density where the oxide would exhibit an influence on current.

A deposit of salts, principally calcium bicarbonate, and clay particles, principally biotite, on electrodes left in place in a loamy sand reduced measured ODR's by an average of more than 50% after 2 months compared to ODR's from reinserted electrodes in the same soil. The deposits did not form to such an extent on electrodes in a clay and ODR measurements from in‐place electrodes remained comparable to those from reinserted ones throughout the 2‐month period.

A nitric acid pretreatment procedure provided an electrode cleaning technique without any abrasion and brought electrodes to an oxidized condition after prolonged use or disuse.
Sand and Cotton Bur Mulches, Bermudagrass Sod, and Bare Soil Effects on: I. Evaporation Suppression
Authors: Wiegand C. L. , Heilman M. D. , Swanson W. A.
Published: July 2010

Moisture, water table, and temperature changes were recorded for 3 years under four surface cover conditions used for salinity reclamation under the rainfall conditions (58 cm/yr during the study) in the Lower Rio Grande Valley of Texas. Surface cover conditions were (i) 1.5‐cm‐thick mortar sand mulch; (ii) 44,800 kg/ha cotton bur mulch (Gossypium hirsutum); (iii) coastal bermudagrass sod (Cynodon dactylon L.); and (iv) bare fallow.

Relative profile moisture depletion among treatments and soil moisture suctions measured in the surface 50 cm of the soil show that even shallow soil depths remained moist during long, rainless periods under the sand and cotton bur mulches. The amount of water in the surface 61 cm of soil for 37 measurement dates averaged 1.32 cm more under the burs, 1.38 cm more under the sand much, and 2.85 cm less under the grass sod, respectively, than under the bare soil condition. Monthly means of daily maximum and minimum soil temperatures measured at the 10‐cm depth were both in the order sand mulch > bare soil > bur mulch > bermudagrass sod, but the higher soil temperatures under the sand mulch did not obviate its effectiveness in evaporation suppression. Since soil moisture suctions were low under the mulches, even moderate rainfall amounts rewet the soil to field capacity and should have effected leaching.
Effect of Plant Weathering of Soil Clays on Plant Availability of Native and Added Potassium and on Clay Mineral Structure
Authors: Conyers E. S. , McLean E. O.
Published: July 2010

Plants were grown for 4 weeks in suspensions of Brookston and Clermont soil clays for the purpose of removing K. At weekly intervals, samples of the plant‐weathered clays were removed for determination of K uptake by soybean plants (Glycine max) and for X‐ray analysis. Labeled K was added and equilibrated with the clay samples. Specific activity of 42K adsorbed by cation‐exchange resin confined in cellulose tubing was lower than that added to the clay and decreased relatively more with time of weathering. This indicated that K was released from the clays diluting the 42K added, but that fixation of 42K (and 39K) added eventually became relatively greater than K released.

Plant uptake of K during the weekly 1‐hour uptake periods was determined from 42K uptake and specific activity of 42K adsorbed by the resin at weekly intervals. Amounts of K uptake initially decreased with time or did so ultimately as more K was removed from the clays. X‐ray diffractograms revealed that plant weathering altered the basal spacings of the clays. Weathering effects noted were partial degradation of illite and apparent reduction in amount of kaolinite in both soil clays, and reduction in amount of vermiculite in the Clermont.
Plant Uptake and Residual Value of Six Tagged Nitrogen Fertilizers
Authors: Broadbent F. E. , Nakashima T.
Published: July 2010

Three ammonium‐tagged fertilizers, two nitrate‐tagged fertilizers, and N‐tagged urea were added to three soils in green house pots. Plant uptake of surface‐applied fertilizer N was measured by growing four crops over a period of 314 days. In another experiment, tagged ammonium sulfate, ammonium nitrate, and aqueous ammonia, were compared using band application. With surface application, uptake of fertilizer N in plant tops varied from 35 to 71%, with nitrate sources showing the higher values. Residual N in soil ranged from 18 to 41%, and its availability decreased with successive crops. All ammonium sources suffered some loss with surface application, especially aqueous ammonia, but losses were negligible with band application.

Availability of soil N was influenced to some extent by the nature of the fertilizer applied. From 5 to 13% of the soil N was utilized by four crops.
Molybdenum in Plant Tissues: Analysis by an X‐Ray Spectrographic Volume Dilution Technique
Authors: Theisen A. A. , Pinkerton A.
Published: July 2010

A volume dilution method, previously shown to give good good results for the X‐ray spectrographic determination of Mn, Fe, and Zn in plant materials, is shown to be suitable for the analysis of Mo in ashed plant tissues. Agreement with chemical determination is good for 10 out of 11 plant tissue samples.
An Improved Membrane System for Oxygen Probes
Authors: Enoch H. , Falkenflug V.
Published: July 2010

A probe, designed to measure partial oxygen pressure in a three‐phase system such as soil‐water‐air, is described. The probe is almost equally sensitive in the gaseous or liquid phase of the system. In place of the usual single membrane, the oxygen probe is fitted with two separated membranes and a spacer which form a gas‐filled diffusion chamber. The variable diffusion impedance of the environment is hereby reduced to insignificance by increasing the contact area between the environment and that part of the membrane through which the oxygen diffusion takes place. The probe can be used for continuous or discontinuous measurements.
Self‐Diffusion of Sodium Ions in Frozen Wyoming Bentonite‐Water Paste
Authors: Murrmann R. P. , Hoekstra P. , Bialkowski R. C.
Published: July 2010

Self‐diffusion of sodium ions in frozen Na‐Wyoming bentonite paste was studied at different subzero temperatures using a radioactive tracer technique. The value of the apparent self‐diffusion coefficient decreased rapidly from 8.8 × 10‐7 cm2 sec‐1 at −0.6C to 4.3 × 10‐7 cm2 sec‐1 at −3.0C but then decreased slowly to 1.7 × 10‐7 cm2 sec‐1 at −15.0C. Thus, the rate of ion diffusion in the frozen bentonite paste was relatively high even at low temperatures. The reduction in ion mobility with decreasing temperature was primarily a consequence of a concurrent decrease in film thickness of the unfrozen water.
Effects of Adding Charcoal During Dilute Acid Extraction of Manganese from Soils
Authors: Gilliam J. W. , Cox F. R. , Reid P. H.
Published: July 2010

Addition of charcoal during extraction of soil with dilute HCl + H2SO4 increased the amounts of manganese and iron extracted but had little or no effect on the copper, zinc, and aluminum extracted concurrently. Experiments indicated that the increase in extractable manganese due to the presence of charcoal was not a consequence of an increase in efficiency of extraction of reduced manganese already present but resulted from a reaction in which forms of manganese of low solubility were reduced and made soluble and in which CO2 and CO were evolved. The amounts of manganese extracted from soils by dilute HCl + H2SO4 in the presence of charcoal and by dilute HCl + H2SO4 containing hydroquinone were highly correlated. The effect due to charcoal increased with the acidity of the extracting solution, the time of extraction, and the amount of charcoal added.