bluuebunny/crossref_metadata_2025_split huggingface dataset:
Local Soil‐landscape Relationships in Western Iowa: II. Quantification of Pedologic and Geologic Effects
Authors: Huddleston J. H. , Walsh J. A. , Jowett D. , Riecken F. F. 
Published: July 2010

AbstractThe soil‐landscape system consists of contiguous units of noncalcareous loess, calcareous loess, and alluvium. Soil data from each unit were subjected to a principal components analysis. The objective was to identify specific pedologic and geologic processes that have contributed to soil formation and to quantify the separate effects of each process. Factors generated by the analysis were interpreted as representing (i) processes of parent material formation, whose effects are inherited; (ii) processes of pedogenesis that modify initial‐state distributions; (iii) processes of loess stratification; (iv) processes of hillslope erosion and footslope sedimentation; (v) processes of nutrient concentration; and (vi) processes of nitrate mobility. The percentage variance removed by each factor indicates the relative strength of each process. Parent material effects dominate in calcareous loess, but pedogenic profile modifications dominate in noncalcareous loess. In both materials, the effects inherited from geologic processes of loess stratification could also be identified. Two processes in alluvium express effects of erosion‐sedimentation and of nutrient concentration in the waterway center. Pedogenesis is of tertiary importance to soil formation in alluvium.
Toposequence Relationships of Dystrandepts in Costa Rica
Authors: Alvarado A. , Buol S. W. 
Published: July 2010

AbstractThree Typic Dystrandepts; medial, isothermic, profiles located on a slightly convex position, a concave position, and a 20% slope were studied. The horizontal distance between adjacent profiles was approximately 100 m.The soils were characterized by chemical, mineralogical, micromorphological and physical methods to establish the nature of the differences among them, and to develop hypotheses of their genesis.The genesis of these soils appears to be controlled by composition and age of the parent material and only slightly influenced by the relief. Periodic additions of pyroclastic materials build up thick A horizons rich in plagioclases and pyroxenes. Halloysite was evident in the deeper and older underlying materials where it was also observed in sand‐sized aggregates. The B horizons in the convex and sloping topographic positions were slightly more enriched with iron, which seemed to be translocated from the A horizons, than was the profile in the concave position.Differences due to topographic position did not affect taxonomic placement of the profiles in the family category.
Trials with Sulfur‐Coated Urea and Other Nitrogenous Fertilizers on Pinus radiata in New Zealand
Authors: Mead D. J. , Ballard R. , Mackenzie M. 
Published: July 2010

AbstractSulfur‐coated urea fertilizers were included in six experiments with seedlings of Pinus radiata D.Don. The fertilizers were applied in notches alongside seedlings about 2 months after planting, and tree growth was measured for 2 or 3 years. After slash burning on a strongly weathered clay soil, slow‐release nitrogen fertilizers, including three formulations of S‐coated urea, proved more effective than urea. On a more fertile pumice soil, on both slash burnt and unburnt sites, no response to N fertilizers was detected. However, where the topsoil of this soil type had been either completely or partially removed (a log landing and a windrowed area, respectively) a response to N occurred. In these two disturbed areas S‐coated urea showed no advantage over conventional soluble NH4‐N fertilizers. There were no differences between the effectiveness of the three formulations of S‐coated urea at any of the experimental sites.
The Growth of Disturbances in Unstable Infiltration Flows
Authors: Philip J. R. 
Published: July 2010

AbstractThe stability analysis of the delta‐function model of infiltration yields a maximum wave‐number for unstable disturbances, Mcrit, and a wave‐number for maximum amplification, M*. The “column effect,” i.e. the suppression of instability in laboratory columns, depends on Mcrit; and the dimensions of fingers in unstable flows can be expected to depend on M*. When instability is induced by a sudden jump of G, the water pressure gradient behind the wetting front, Mcrit and M* may be evaluated simply and directly. When, on the other hand, instability emerges during gradual increase of G, it is necessary to study the amplification of disturbances during the whole course of increase of G through positive values.Such a study is made for one example of instability induced by air compression and for one where it is induced by increase of conductivity with depth. Both exhibit qualitatively similar patterns of amplification: disturbances of small M (wave‐number) begin to be amplified sooner, but are ultimately overtaken by some disturbances of larger M starting later. Definite values of M* are found, and the results discussed with special reference to fingering and to the column effect.
On the Differential Equation for the Equilibrium Moisture Profile in Swelling Soil
Authors: Sposito Garrison 
Published: July 2010

AbstractDifferential equations which describe the equilibrium vertical distribution of moisture in swelling soil have been derived previously using both thermodynamic and fluid‐mechanical methods. A fundamental disagreement exists between these expressions which is resolved in this paper through a detailed thermodynamic analysis of the equilibrium state of water in a swelling soil. The correct differential equation for the moisture profile is found and the discrepancy between previous results is shown to have been caused either by introduction of extrathermodynamic variables or by an incorrect handling of the effect of overburden pressure on the soil water.
Soil Potassium Relationships as Indicated by Solution Equilibrations and Plant Uptake
Authors: Munn D. A. , McLean E. O. 
Published: July 2010

AbstractFour Ohio soils of wide range in K release capability were initially K‐treated (0, 100, 200, 800 ppm) and successively cropped three times with corn in a growth chamber. Aliquots of the soils with and without K added and before and after cropping were assayed by extraction, equilibration, and plant uptake techniques for the effects of cropping and K‐treatment. Uptake of K by the corn was closely related to the K release capabilities of the soils. Exchangeable K increased as rate of K increased. Initial cropping decreased the exchangeable K in all soils eliminating the effect of K treatments on exchangeable K. However, after initial cropping where no K was added, exchangeable K varied sixfold from the lowest to the highest. Nonexchangeable K removed with H2SO4 initially reflected K additions, but after the first crop, the values decreased progressively as K release capabilities of the soils increased. Parameters from Q/I isotherms of the soils gave correlations with percentage and total K contents of assay crops less satisfactory than for exchangeable and H2SO4 extractable K. There was a tendency for prior cropping to increase the fixation and reduce the plant recovery of subsequently applied K in the two soils high in clay and total K.
Initial Release of Nitrogen from Ureaform Under Field Conditions
Authors: Hadas Aviva , Kafkafi U. , Peled A. 
Published: July 2010

AbstractThe mineralization of ureaform in the soil has been observed during the three weeks following application in a small plot of a banana (Musa Cavendishii, var. Cavendish) plantation at two different seasons of the year. In the cooler season ammonium and nitrite accumulated and persisted for 2 weeks. In the warmer season, only ammonium accumulated during 2 days. The rate of mineralization, calculated as a first‐order reaction, was greater at the higher temperature, but the rate constants were about 10 times greater in the field than in previous laboratory experiments. The reasons for this are probably changes in microbiological activity and mineralization of nitrogen from sources other than the fertilizer.
Clay Mineralogy, Physical, and Chemical Properties of Some Soils in Arid Regions of Iran
Authors: Mahjoory Ramez A. 
Published: July 2010

AbstractCoarse, medium, and fine‐textured soils were studied in three different arid regions of Iran, namely Gazvin, Karaj, and Kooshkak alluvial plains, respectively. Six representative pedons including 33 samples were tested.X‐ray analyses indicated the clay mineral components of soils consist of some discrete vermiculite, chlorite, clay mica (illite), kaolinite, and interstratified clay mica‐vermiculite or chlorite.Quantitatively, vermiculite and clay mica are the major clay mineral components in these soils. The average vermiculite contents of coarse, medium, and fine‐textured soils are calculated as 41.7, 41.4, 42.4%; clay mica contents are 26.3, 38.0, and 20.0%, respectively. The amount of clay mica decreases significantly with depth in most of the soils studied.Physico‐chemical determinations revealed the soils are calcareous throughout and the carbonates increase from coarse‐ to fine‐textured soils. The morphogenetic sequences of carbonate accumulation are divided into three morphogenetypes. Most organic matter contents are < 1%. They decrease with depth but increase from coarse‐ to fine‐textured soils.Soils with poor structural development contain > 20% CaCO3, and have considerable amounts of vermiculite but lower amounts of clay mica. The slight accumulation of silt, clay, and carbonates at the surface of some soils may indicate the influence of atmospheric addition in the genesis of the soils studied. Two of the soils are classified Typic Camborthids, two of them Xerollic Camborthids, and the other two, Xerollic Calciorthids.
Thick Bh Horizons in the North Carolina Coastal Plain: I. Morphology and Relation to Texture and Soil Ground Water
Authors: Daniels R. B. , Gamble E. E. , Holzhey C. S. 
Published: July 2010

AbstractSpodosols in North Carolina have thick, vertically continuous Bh horizons wherever the parent material is a sand or loamy sand texture that has a high water table and a downward flow of ground water. These Bh horizons are 5–9 m thick, and their lower boundaries are always a few centimeters above a less permeable layer or a bed of greenish‐gray sand. Pollen counts and the general morphology indicate that the thick Bh horizons are post depositional features. Percolating organics, monitored by shallow wells, move from the surface downward in quantities greater than necessary to account for the whole Bh horizon thickness.
Crop Production Function Determinations as Influenced by Irrigation and Nitrogen Fertilization Using a Continuous Variable Design
Authors: Bauder J. W. , Hanks R. J. , James D. W. 
Published: July 2010

AbstractContinuous variable (CVD) and randomized block, split plot (RBSD) designs were used to produce data from which production functions were developed relating corn yield to soil water and nitrogen fertilizer. Data were collected at Logan, Utah in 1972 and Farmington, Utah in 1973.The CVD water and nitrogen treatments, respectively, were sequential or continuous and not randomized. The design is compact but has some statistical uncertainty. The CVD had 7 or 8 soil water (W) levels and 22 or 24 nitrogen (N) levels compared to 4 W and 5 N levels for RBSD. The area used for the RBSD was 3 or 4× that used for the CVD.The data analyzed for the CVD led to the same conclusions as the analysis of the RBSD. The production function (regression equation) at Logan was different from that at Farmington except when comparisons were made on a relative basis.
Nitrate Movement and its Distribution in the Soil Profile of Differentially Fertilized Corn Watersheds
Authors: Schuman G. E. , McCalla T. M. , Saxton K. E. , Knox H. T. 
Published: July 2010

AbstractNitrate movement within the 6.1‐m soil profile of a watershed in southwestern Iowa, fertilized at 448 kg N/ha per yr, resulted in a 720‐kg/ha increase in NO3‐N below the corn root zone during the 3‐year study. The NO3‐N concentration of the baseflow from the watershed increased during this period, indicating that some of the leached NO3‐N reached the ground water. The watershed fertilized at the recommended N rate (168 kg/ha per yr) did not increase the quantity of NO3‐N below the corn root zone; however, some NO3‐N leaching did occur.Between April 1971 and April 1974, the accumulation of NO3‐N in the profile of the excessively fertilized watershed moved from the 1.0‐ to 3.1‐m depth. Three‐fourths of NO3‐N movement occurred between June 1972 and April 1973 when 80 cm of precipitation caused 21 cm of percolation below the corn root zone (183 cm). The watershed fertilized with 168 kg N/ha per yr did not show any zones of significant NO3‐N accumulation in the soil profile at any of the sampling dates.The depth to the water table on the lowest contour sampled on the excessively fertilized watershed was 4.6 and 4.9 m in April 1973 and April 1974, respectively. The average NO3‐N concentration for these two sampling dates at the water table depth increased from 3.7 to 12.9 ppm. The average NO3‐N concentration at the water table depth on the normally fertilized watershed was 2.0 and 4.5 ppm in April 1973 and April 1974, respectively, with a water table depth of 3.0 m.
Solubility and Solubility Product of Dicalcium Phosphate Dihydrate in Aqueous Solutions and Soil Solutions
Authors: Bennett A. C. , Adams Fred 
Published: July 2010

AbstractThe solubility product (Ca2+)(HPO42‐) of CaHPO4 · 2H2O was determined in several aqueous solutions containing ions common to soil solutions. Extrapolation of analytical Ca and P concentrations to zero ionic strength yielded pKSD values ranging from 6.54 to 6.59 and averaging 6.57 for 10 aqueous salt solutions. A method of successive approximation that computed ionic activity was used to determine the pKSD for three concentrations of 15 different aqueous salt solutions saturated with CaHPO4 · 2H2O. Calculated pKsp values ranged from 6.44 to 6.63; the average was 6.55. Eight soil samples that varied widely in pH and soil‐test P were treated with CaHPO4 · 2H2O at rates of 600 to 3,000 ppm P. Soil solutions were displaced, analyzed, and (Ca2+)(HPO42‐) was calculated. Eight of the 20 samples of soil were considered to be saturated with CaHPO4 · 2H2O because their (Ca2+)(HPO42‐) values were approximately the same as that for similar aqueous salt solutions. It was concluded that the presence of excess CaHPO4 · 2H2O in soil could be inferred by ion‐activity products of displaced soil solutions.
Degradation of a Nonionic Surfactant in Soils and Peat
Authors: Valoras N. , Letey J. , Martin J. P. , Osborn J. 
Published: July 2010

AbstractNonionic surfactants are used to improve water movement into water‐repellent soils. The effective longevity of treatment and potential water pollution are affected by surfactant degradation. Degradation of 14C‐labeled Soil Penetrant 3685, a nonionic surfactant, was measured in incubation studies in the laboratory. Three soils and one peat, numerous surfactant concentrations, and two soil‐moisture levels were used as experimental variables. Plots of degradation percentage versus time produced “S” type curves. Increasing the concentration increased the lag period prior to most rapid degradation. The most rapid and highest percentage of degradation were generally associated with soil materials having the lowest adsorptive capacity for the surfacant. From about 75 to 85% of the added 14C was evolved as 14CO2 in 1 year for the most favorable conditions for degradation. Degradation rate was decreased by decreasing the soil‐moisture content. Degradation of soil organic matter was not greatly affected by surfactant applications—< about 10,000 ppm, but progressively decreased with higher surfactant concentrations.
Effects of Vegetation on the Distribution of Carbon, Iron, and Aluminum in the B Horizons of Northern Appalachian Spodosols
Authors: De Kimpe C. R. , Martel Y. A. 
Published: July 2010

AbstractThe effects of coniferous and deciduous vegetation on the distribution of C, Fe, and Al oxides in the B horizons of 10 Podzolic (Spodic) soils of the Northern Appalachian Mountains were investigated. Organic C was extracted with 0.5N NaOH. Iron and aluminum oxides were extracted with pyrophosphate and with dithionite‐citrate‐bicarbonate. Significantly more Fe and Al was found under conifers than under deciduous trees in the upper part of the B horizon. Aluminum content was also higher in the lower part of the B horizon.After fractionation of the organic matter, fulvic acids appeared as the most important fraction. They contained on the average 52% of the C and > 90% of the Fe and Al involved in organo‐metallic complexes. These were found in significantly greater amounts in the upper part of the B horizons of soils developed under conifers.The content of sesquioxides in organo‐metallic complexes is a criterion for the classification of the Spodic or Podzolic B horizon in both the US and Canadian systems of soil classification. Variations in sesquioxides due to vegetation type may exclude some Podzolic soils of the Northern Appalachian Mountains developed in fine‐textured material of being classified as Spodosols in the US system.
Salt and Water Balance in Imperial Valley, California
Authors: Kaddah M. T. , Rhoades J. D. 
Published: July 2010

AbstractSalt balance (SB = Veff.w · Ceff.w − Vinf.w · Cinf.w) of the Imperial Valley (IV) has been determined annually since 1943 by the Imperial Irrigation District. Salinity trends in the valley are assessed from biweekly measurements of the volume, V, and concentration, C, of influent, inf.w, and effluent, eff.w, waters. In this paper we summarize the SB data, evaluate their significance, and suggest approaches for assessing salinity trends in the soils of the valley.The SB data reflected the cropping and water use patterns in the valley. However, the data were insufficient to distinguish origin of water and salt in effluent waters or to provide information about changes in root zone salinity. In 1973 total evapotranspiration (ET) by crops in the valley was estimated to be 229 × 103 ha‐m, equivalent to 70% of the water delivered to the farmers. Deductions as to Cl‐ composition of influent and effluent during 1973 suggest that the Cl‐ load in the effluent water was contributed as follows: 54.7% from ground water, 35.0% from root zone drainage water, and 10.3% from tail water (runoff).A more definitive interpretation of the salt balance data would require more accurate evaluation of volume of tail and consumptive use waters and volume and concentration of root zone percolate. If this information cannot be obtained on a valley‐wide basis, then an alternative approach is to establish a representative number of soil salinity monitoring plots through the valley and assess their root zone salinity periodically.
Stabilizing Soil Aggregates with Phosphoric Acid
Authors: Thien Steve J. 
Published: July 2010

AbstractFour P‐containing fertilizer materials (H3PO4, liquid and dry ammonium polyphosphate, and triple superphosphate) were compared for ability to increase water stability of aggregates in an acid soil. Only agricultural‐grade H3PO4 significantly increased aggregate stability—from 6.2% in the untreated samples to 45.2% in samples treated with 228 kg P/ha. The induced stability lasted through at least five wetting and drying cycles, each cycle consisting of 1.8 cm of water applied over a 1‐hour period followed by 2 weeks of air drying. Water stability of soil aggregates treated with H3PO4 increased as H3PO4 was increased to 228 kg P/ha (maximum tested). Exchangeable Al increased from 0.2 ppm Al in untreated soil to 2.55 and 2.85 ppm Al in soil layers receiving 112 and 224 kg P/ha, respectively. While the highest P concentrations tested caused soil pH to temporarily drop approximately one unit, pH returned to the pretreated value after four wetting cycles. Scanning electron microscope photos showed more fine particles present in the treated aggregates than in the untreated samples. Phosphoric acid apparently modifies the soil physical environment by preserving the fine‐particle content of aggregates which in turn increases their water stability.
Plinthite Characterization in Selected Southern Coastal Plain Soils
Authors: Wood B. W. , Perkins H. F. 
Published: July 2010

AbstractSamples of plinthic horizons from five soil series were collected in the Southern Coastal Plains Province of Georgia. Plinthite and various colors of soil material in each horizon were separated and analyzed for particle size distribution, Fe2O3 content, and mineralogy.Iron segregation is greater in plinthic than nonplinthic soil formations in subsurface horizons. In the upper part of B2t horizons where plinthite is nearest the surface, Fe is present as amorphous hydrated oxides and goethite giving the soil matrix a brownish‐yellow color. In the plinthite, there is a higher Fe content than in surrounding non‐plinthic soil and the Fe is present as the dehydrated oxide hematite in addition to the amorphous hydrated oxides and goethite. The lower part of the B2t horizon is composed of three color phases in which the Fe content as well as the form of Fe differs. In the pale‐colored soil (white, pale yellow), total Fe is relatively low. Iron occurs in greater amounts in the forms of goethite and amorphous compounds in the brownish yellow soil material. Plinthite has the highest Fe content which occurs as hematite, goethite, and amorphous hydrated oxides.Particle size distribution varies within plinthic horizons. Nonplinthic soil materials have higher percentages of <2µm particles than was found in plinthite. Kaolinite in the clay fraction of plinthite is in a more disordered crystalline state than in the matrix soil. The silt fraction of the soil matrix contains quartz in the pale‐colored soil and quartz and goethite in the yellow soil. Silt fractions of plinthite contain quartz, hematite, and goethite. The coarser texture of the plinthic material appears to be a result of destruction of kaolinite and crystal growth of Fe compounds. The end product of this process is hardened ironstone nodules or septaria which contain quartz, hematite, goethite, and weakly crystalline kaolinite.
Correlation of Plant Manganese with Extractable Soil Manganese and Soil Factors
Authors: Randall G. W. , Schulte E. E. , Corey R. B. 
Published: July 2010

AbstractThe availability of Mn on 37 low and 20 high organic matter Wisconsin soils was determined by growing oats (Avena sativa L.) and ryegrass (Lolium perenne), respectively, in consecutive greenhouse studies. The Mn uptake values were used to develop prediction equations by means of multiple regression analysis with Mn extracted by various extracting solutions (18 extractants for the low and 13 for the high organic matter soils) plus various functions of soil pH and organic matter as the independent variables.On the low organic matter soils (O.M. < 6%), using only the Mn test, the best prediction values with uptake were obtained with total Mn, and with the 0.1N H3PO4 and 0.01M EDTA in 1N NH4OAc extractants (R2 = 57, 50 and 49%, respectively). Inclusion of soil pH and organic matter with the soil test values resulted in Mn uptake being predicted best by the 0.01M and 0.05M EDTA extractants (R2 = 68% for both). The contribution of the soil test in the prediction equation was strongest when the 0.1N H3PO4, 0.01M EDTA in 1N NH4OAc, 0.05M EDTA or DTPA (pH 7.3) extractants were used.On the high organic matter soils (4.2 to 78.5% OM), a regression equation with soil pH, organic matter and their cross‐product as the independent variables accounted for 70% of the Mn uptake variability. By including test × pH and test × organic matter for the 0.01M EDTA in 0.1M (NH4)2CO3 or DPTA (pH 10.7) extractants, the R2 values were increased to 80%. Soil test Mn or its squared value did not contribute significantly to any of the prediction equations; whereas, soil organic matter and the pH × organic matter cross‐product contributed to all.