bluuebunny/crossref_metadata_2025_split huggingface dataset:
Manganese Oxide Analysis in Soils by Combined X‐ray Diffraction and Selective Dissolution Methods
Authors: Tokashiki Y. , Dixon J. B. , Golden D. C. 
Published: July 2010

AbstractIt is difficult to identify the Mn oxides in many soils due to their poor crystallinity, low concentration, the diffuse nature of the x‐ray diffraction patterns, and the coincidence of diagnostic peaks with those of associated minerals. A selective dissolution procedure is proposed to characterize Mn oxides and the associated minerals by using successive sodium hydroxide, hydroxylamine hydrochloride, and dithionite‐citrate‐bicarbonate (DCB) treatments. Mineral composition was determined by x‐ray diffraction analysis before and after each treatment. Three samples of soil Mn nodules from Okinawa Island, Japan, and synthetic sodium birnessite and lithiophorite ore were used as test materials. The NaOH treatment destroyed kaolinite and gibbsite but concentrated birnessite, lithiophorite, and goethite. Heat treatment followed by x‐ray diffraction analyses indicated that birnessite, lithiophorite, and goethite were destroyed at 200, 400, and 300°C, respectively. Birnessite was dissolved by hydroxylamine hydrochloride leaving lithiophorite and goethite unchanged. A DCB treatment following hydroxylamine hydrochloride dissolved lithiophorite and goethite leaving a layer silicate residue. The chemical separation and dissolution procedures were effective in characterizing the Mn oxides in soils.
Kinetics of Ion Exchange on Clay Minerals and Soil: II. Elucidation of Rate‐limiting Steps
Authors: Ogwada R. A. , Sparks D. L. 
Published: July 2010

AbstractKinetics of K+ adsorption were investigated on kaolinite, a Chester loam soil and vermiculite using static, stirred, and vortex batch techniques. The objective of this study was to elucidate the rate‐limiting steps for K+ adsorption on the clay minerals and soil. We hypothesized that it is possible under laboratory conditions to set up a system in which the global rate is limited by mass transfer (under static conditions), in which only the intraparticle diffusion step is rate‐limiting (stirred system), and a system in which the rates of film and intraparticle diffusion are both relatively rapid, presumably rendering the reaction step to be rate‐controlling (vortex batch). We derived and assigned additive resistance relations to the three proposed experimental methods according to the above stated assumptions. Observed rate coefficients obtained from static, stirred and vortex batch systems were combined and used to calculate rate coefficients for film diffusion (kf), intraparticle diffusion (kI), and reaction kinetics (kr) in a static system. Film diffusion and intraparticle diffusion rate coefficients were approximately the same in vermiculite, indicating that both steps were rate‐determining. In kaolinite and the Chester soil, film diffusion was the rate‐limiting step. These conclusions were also verified using the parabolic diffusion equation. The kI values were on the avg 8.7 times as great as kf values in the kaolinite system, indicating that intraparticle diffusion was not important for kaolinite. Higher energies of activation for adsorption (Eaa) were observed for the reaction step than for intraparticle diffusion or film diffusion steps. These findings were expected since chemical reactions are more sensitive to temperature changes than diffusion processes.
Sulfate Reduction and Calcium Carbonate Equilibria in a Central California Histosol
Authors: Deverel S. J. , Whittig L. D. , Tanji K. K. 
Published: July 2010

AbstractSulfate (SO2‐4) reduction and bicarbonate (HCO‐3) production were studied in three organic soil profiles removed intact from the California Delta area. The water table was maintained at approximately 0.75 m from the soil surface in columns 1.22 m in height. The partial pressure of carbon dioxide (PCO2) was monitored throughout the experiment. Extracted soil solutions were evaluated with respect to calcite solubility. Sulfate reduction was found to follow first‐order kinetics for three different initial SO2‐4 concentrations. Bicarbonate production followed approximately the stoichiometry of the organic matter oxidation‐SO2‐4 reduction reaction. Soil solutions extracted below the water table were found to be saturated with respect to calcite depending on the PCO2 and the initial SO2‐4 concentration.
Effect of Acidity on Denitrifcation and Nitrous Oxide Evolution from Atlantic Coastal Plain Soils
Authors: Weier K. L. , Gilliam J. W. 
Published: July 2010

AbstractThe effect of acidity on denitrification and nitrous oxide production in six soils from the Atlantic Coastal Plain was estimated using laboratory incubations of flooded soil for periods up to 21 d. Increased denitrification rates were associated with a decrease in acidity in all soils but most of the effect occurred above pH 6.5. Some accumulation of NH+4‐N occurred in all soils and was positively correlated to the NO‐3‐N lost from the system. Small quantities of NO‐2‐N were formed in all soils. Larger amounts of NO‐2‐N were found at pH 5.0 and 4.7 for two soils. Nitrite‐N accumulation corresponded to the release of large quantities of N2O suggesting a possible relationship between NO‐2‐N accumulation and N2O production. Nitrous oxide evolved, as a percentage of NO‐3‐N lost, increased with increasing acidity with maximum N2O being evolved at pH values ≤5.8. Above pH 5.8, evolution of N2O virtually ceased. Since all six Coastal Plain soils are generally <pH 5.8, a high percentage of nitrogen being lost from these soils through denitrification is as N2O.
Soil Properties Affecting Formation of Nitric Oxide by Chemical Reactions of Nitrite
Authors: Blackmer A. M. , Cerrato M. E. 
Published: July 2010

AbstractGas chromatography was used to determine the amounts of nitric oxide (NO) in the headspaces above samples of 28 soils that had been autoclaved, treated with nitrite, and sealed in all‐glass flasks with He atmospheres for 18 h. When nitrite was added at a rate of 100 mg N kg−1 soil, the amounts of NO‐N found ranged from less than 1 to 35 mg kg−1 soil, and statistical analyses indicated that 95% of the variability in the amounts of NO found among the soils could be explained by a model that considered only soil organic C content, pH, and an interaction of these factors. The formation of CO2 and the ratios of NO to NO‐3 observed indicate that production of NO cannot be explained solely by self‐decomposition of nitrous acid. When various amounts of soil were added to identical samples of nitrite solution, the amounts of NO‐N found increased with amounts of soil added. These findings indicate that NO is formed by reactions of nitrite with the organic fraction of soils as well as by self‐decomposition of nitrous acid.
Relative Toxicities of Inorganic Aluminum Complexes to Barley
Authors: Cameron R. S. , Ritchie G. S. P. , Robson A. D. 
Published: July 2010

AbstractThe inorganic forms of Al in the soil solution that decrease plant growth in acid soils have not been clearly identified. Therefore, we examined the effects of Al and its complexes with F‐ and SO2‐4 on the root elongation of barley (Hordeum vulgare) in nutrient solutions containing 3333 µmol Ca L−1 and 6 µmol B L−1 at pH 4.5. The anions were chosen because of their presence in the soil solution at levels sufficient to complex Al. The toxicity of 0 to 100 µmol Al L−1 was studied in the presence of 0 to 10 µmol F‐ L−1 or 0‐3300 µmol SO2‐4 L−1. The elongation of roots of barley seedlings was correlated with Al3+ concentrations but not with total soluble Al or Al complexed with F‐ and SO2‐4. This could be one of the reasons why measurements of labile Al using complexing agents have not always been successful at distinguishing between Al‐toxic and nontoxic soils.
Water Table Characteristics and Water Chemistry of Seasonally Wet Soils of Southwestern Ohio
Authors: Ransom M. D. , Smeck N. E. 
Published: July 2010

AbstractThe seasonally high water table in Clermont (Typic Glossaqualfs) and Avonburg (Aeric Fragiaqualfs) soils of southwestern Ohio was investigated by monitoring variations in water table depth and in water chemistry of the vadose and upper saturated zones. Piezometers were installed for two pedons at three depths ranging from 70 to 180 cm, and soil‐water samples were collected using 0.1‐MPa porous ceramic cups installed in triplicate at four depths ranging from 32 to 170 cm. During the period of this study (April 1982–June 1983), the water table occurred within 30 cm of the surface during winter and early spring, fell rapidly to a depth of about 150 to 180 cm during late summer and early fall, and then returned to within 30 cm of the soil surface during late fall and early winter. Soil‐water exhibited ranges in pH (5.2–8.6), Eh (153–543 mV), electrical conductivity (7.0–91.5 mS m−1), dissolved O2 (0.6–6.1 mg L−1), Ca (2.5–64.1 mg L−1), Fe(II) (0–3.87 mg L−1), and Fe(III) (0–11.48 mg L−1). Soil‐water chemistry was a function of season and depth below the soil surface. While the dissolved O2 content decreased with depth, Eh and pH increased. Alternating periods of reduction and oxidation were suggested by significant seasonal variation in the variables monitored. Reducing conditions were indicated by the presence of Fe(II) in solution and an Eh of <400 mV, both of which occurred in the Clermont soil at the uppermost sampling depth during the April through June period. This period was characterized by saturated conditions and a soil temperature higher than 8°C. The highly variable Fe(II) and Fe(III) contents indicated that oxidation‐reduction reactions occurred primarily in microenvironments. The soil‐water system was not at internal equilibrium as evidenced by (i) the simultaneous occurrence of dissolved O2 with reduced C (organic matter) and Fe (II), and (ii) a mixed potential for Eh that did not correlate with dissolved O2 content.
Surface Soil Variability of a Map Unit on Niger River Alluvium
Authors: Ameyan Oluwole 
Published: July 2010

AbstractExamination of an adequate number of sample points is a prerequisite for valid generalizations in soil surveys. The number of sample points required depends upon a host of factors, including the spatial variability of the properties under investigation. This study examines the spatial variability of textural and chemical soil properties in the surface horizon of two sample areas mapped as Ozugbi series (Typic Humaquepts). From a knowledge of the dispersion characteristics of the soil properties, the number of sample points required to estimate each property at different levels of precision was determined. There were marked contrasts in the variability levels of the soil properties, and, hence, in the number of samples required to estimate each property, between the sample sites and within the map unit as a whole. The pH is the least variable of the properties examined and, hence, needs the smallest number of samples for estimation.
Irrigating Row Crops from Sod Furrows to Reduce Erosion
Authors: Cary J. W. 
Published: July 2010

AbstractKentucky bluegrass (Poa pratensis L.) sod furrows were established to stablize the soil. The furrows were used to irrigate corn (Zea mays L.), wheat (Triticum aestivum L.), barley (Hordeum vulgaris L.), beans (Phaseolus vulgaris L.), and sugar beets (Beta vulgaris L.). The sod strips containing the furrows were 0.3‐m wide and managed as a permanent living entity. A strip moving machine and a miniature rotary ditcher were developed to maintain the sod furrows. Crops were grown in clean tilled strips 0.9‐m wide between the sod strips. Normal use of fertilizer, herbicides, and cultivation was utilized for the crop rows in the clean tilled strips. This management system eliminated soil erosion, at least doubled the infiltration rate of irrigation water, and allowed the production of satisfactory yields of wheat, barley, dry beans, and corn for silage. Sugar beet production was unacceptable due to competition from the sod.
Estimation of the Philip Infiltration Parameters from Rainfall Simulation Data
Authors: Bach L. B. , Wierenga P. J. , Ward T. J. 
Published: July 2010

AbstractA new, simple technique for estimating the parameters of the two‐term Philip infiltration equation was developed and tested using field‐measured data obtained in the northern Chihuahuan desert of New Mexico. The technique simultaneously provided information on the relationship between the Philip equation parameter A, and the field‐measured hydraulic conductivity. The equation was reformulated as I − cKf = 1/2St−1/2, where I is the infiltration rate, S the sorptivity, t the time, Kf the field‐measured final infiltration rate, and c, a coefficient relating Kf to the Philip parameter A. The final, steady infiltration rate measured in the field was used for the value of Kf. Regressions of (I − cKf) vs. (1/2t−1/2) for values of c between 0 to 1 resulted in optimum c values for each treatment along with their corresponding S values. For the soils in this area, values for the coefficient c were sometimes outside the suggested range of 0.33 to 0.67, and were different for each study site. The regression analysis also showed that the value of S can be highly sensitive to changes in c. Using the values of S and c determined by the proposed method, a comparison was made between computed infiltration rates and measured infiltration rates. The results of this study showed that the prediction method provided adequate fits to field‐measured data, and that the choice of an appropriate c factor is important in determining infiltration parameters from field data.
Chloride Movement in Forest Soils of Nigeria
Authors: Ghuman B. S. , Lal R. 
Published: July 2010

AbstractChloride movement studies were conducted with forest soils at six locations in Nigeria: Ibadan, Ikenne, Ikom, Mokwa, Onne, and Zaria. The soils at Ibadan, Ikenne, Zaria, and Mokwa are classified as Alfisols, those at Ikom and Onne are Ultisols. Potassium chloride was uniformly broadcast on the surface of 145‐ by 145‐cm plots and displaced with 8, 4, 4, and 4 cm of water applied as flood irrigation, keeping a 1‐ to 2‐cm head at the soil surface, at 1‐d intervals. No evaporation was allowed during soil‐water and solute redistribution. Immediately after infiltration of each incremental application of water, duplicate solution samples were obtained using solution samplers installed at 10‐, 20‐, 30‐, 50‐, 70‐, and 90‐cm depths. After infiltration of the first water increment (8 cm) much of Cl‐ moved beyond the 90‐cm depth in the Ikom soil, a well‐structured clayey soil. Chloride concentration peaked at 70‐, 10‐, 30‐, and 20‐cm depths in the Ibadan (gravelly soil), Ikenne, Mokwa, and Onne (leached soil) soils, respectively. There were two Cl‐ concentration peaks, one at a 10‐ and the other at a 70‐cm depth in the Zaria soil, due to textural changes in the profile. There was no appreciable effect of redistribution time of 24 h on the Cl‐ content peak and its dispersion in the Ikenne and Mokwa soils. The effect of redistribution on Cl‐ distribution was considerable in the Zaria soil. Leaching efficiency, calculated as the ratio of the depth of chloride content peak and total water applied (20 cm), was the highest (3.6 cm cm−1 of applied water) in the relatively coarse Mokwa soil and the minimum (0.07 cm cm−1) in the layered Zaria soil.
Effect of Skid Trail Compaction on a Volcanic Soil in Central Oregon
Authors: Allbrook Robert F. 
Published: July 2010

AbstractA skid trail in the Ochoco National Forest, Oregon, was examined to assess the degree of compaction that had occurred as a result of traffic during log harvesting. The soil, classified as a Lithic Cryorthent is a sandy loam derived from rhyolitic and tuffaceous colluvium. Measurements of bulk density and shear strength were made at five positions across the trail and two locations in undisturbed soil. Cores were taken to measure bulk density, moisture content, and moisture retention. Compaction resulted in increases in bulk density of up to 25%, in shear vane strength up to 157%, and in cone index up to 220% along with a decrease in pore space > 10 µm of 69%. Bulk density, vane shear, and penetrometer measurements were found to be highly correlated.
Spatial Variability of Soil pH and Organic Matter in Forest Plantations
Authors: Riha Susan J. , James Bruce R. , Senesac Gail P. , Pallant Eric 
Published: July 2010

AbstractThe spatial variability of soil pH and organic matter concentration in 0.4‐ha plots of 45‐yr old monospecific red pine (Pinus resinosa Ait.), Norway spruce [Picea abies (L.) Karst.], and sugar maple (Acer saccharum Marsh.) stands located on acid Inceptisols in south central New York was examined. Soil was sampled every 5 m along east‐west and north‐south transects and also every 30 cm around selected individual trees from next to the base to a distance of 120 cm. A geostatistical approach was used to analyze the components of variability that were systematically changing in space, correlated in space or not spatially related. There was little spatial correlation between samples with respect to pH or organic matter. However, there was systematic change in space in some horizons due to the presence of the different tree species. After 45 yr the surface mineral horizon under spruce was slightly (<0.3 pH unit) more acidic than under maple. There were also differences between stands of the different species in organic matter of the Oe horizons but not of the surface mineral horizons. The greatest variability in pH occurred between samples taken at the base of individual trees compared to samples taken 30 to 120 cm away. This effect occurred in the organic horizons of all three stands and in the surface mineral horizons under spruce and pine and was greatest for the pine. The approach employed in this study was useful in determining the effect of different tree species on soil chemical properties, where there was no plot replication.
Relative Phytotoxicity of Dicyandiamide and Availability of its Nitrogen to Cotton, Corn, and Grain Sorghum
Authors: Reeves D. W. , Touchton J. T. 
Published: July 2010

AbstractThe nitrification inhibitor, dicyandiamide (cyanoguanidine) (DCD), can improve fertilizer N efficiency; however, yield reductions and phytotoxicity from the use of DCD have been reported. A greenhouse experiment was designed to determine the effect of DCD on growth, chlorophyll concentration and nutrient concentration of corn (Zea mays L.), cotton (Gossypium hirsutum L.), and grain sorghum [Sorghum bicolor (L.) Moench.]. Dicyandiamide‐N/urea‐N combinations of 0:60, 5:55, 10:50, 20:40, 30:30, 40:20, 50:10, and 60:0 mg kg−1 soil were applied to pots containing a Norfolk sandy loam (fine‐loamy, siliceous, thermic, Typic Paleudults) cropped to each of the three species. Increasing the proportion of N as DCD decreased plant dry weight and leaf chlorophyll concentration and increased stem‐leaf N concentrations. Nitrogen recovery decreased curvilin‐early from 103% to 4%, from 64% to −6%, and from 72% to 4% for corn, cotton, and sorghum, respectively, with increasing proportion of N as DCD‐N. The effects of DCD‐N on stem‐leaf tissue concentraitons of P, K, Ca, Mg, Fe, Mn, Zn, and Cu varied with DCD‐N concentration, plant species, and nutrient element. At lower DCD‐N concentrations, most nutrient element concentrations were affected by uptake of NH+4‐N derived from urea; while higher concentrations of DCD‐N resulted in increased nutrient element concentrations as a result of reduced plant growth.
Estimation of Calcium Diffusion Coefficients from Electrical Conductance
Authors: Conkling B. L. , Blanchar R. W. 
Published: July 2010

AbstractDiffusion coefficients for Ca in various horizons of the Bardley, Lebanon, Marshall, and Putnam soils were calculated from electrical conductivity measurements. A diffusion model which separates ion movement in solution from that along soil surfaces provided estimates of Ca movement that agreed with estimates of self‐diffusion measured using 45Ca. The equation has the form dq/dt = (ΛC/Λα) Dliq (dC/dx) + Dsur (dCe/dx), where dq/dt is the flux, ΛC/Λα the ratio of molar conductivities at the given concentration divided by that at infinite dilution, Dliq the diffusion coefficient in the liquid phase at infinite dilution, dC/dx the solution gradient, Dsur the diffusion coefficient along the soil surface, and dCe/dx the gradient of exchangeable concentration. Values of Dliq varied from 0.95 to 1.60 × 10−6 m2s−1 and Dsur from 0.61 to 1.18 × 10−6 m2s−1. Values of Dliq estimated at 0.01 mol/L CaCl2 concentration were 5 to 6% higher than those measured in 1 mol/L CaCl2 and values of Dsur are independent of salt concentration. The ratio of the quantity of Ca diffusing through solution to that along the particle surfaces was < 1 to 4 at 0.01 mol/L salt and approximately 4 to 1 at a 1 mol/L salt level. The estimated Ca diffusion coefficient along the particle surface was in all cases lower in the surface horizon samples than in those from a lower depth in the soil.
Competitive Adsorption of Phosphate with Malate and Oxalate by Tropical Soils
Authors: Lopez‐Hernandez D. , Siegert G. , Rodriguez J. V. 
Published: July 2010

AbstractA study about the competition between organic anions (oxalate and malate)—currently present in the rhizosphere and phosphate for adsorption sites in tropical soils—indicate that in the presence of organic anions, phosphate adsorption by soils is reduced. The extent of such reduction is dependent on the way in which either phosphate or the organic anion are added to the soil. The organic oxyanions studied are more rapidly adsorbed to the soil surface than the phosphate; consequently those anions, when existing in the rhizosphere, can improve the phosphate status of soil.
Sorption of Bromacil, Chlortoluron, and Diuron by Soils
Authors: Madhun Yousef A. , Freed V. H. , Young J. L. , Fang S. C. 
Published: July 2010

AbstractSorption of bromacil (5‐bromo‐3‐sec‐butyl‐6‐methyluracil), chlortoluron [3‐(3‐chloro‐4‐methylphenyl),1,1‐dimethylurea], and diuron [3‐(3,4‐dichlorophenyl)1,1‐dimethylurea] by soils containing contrasting organic carbon (OC) content was studied. The sorptive capacity of the soils was assessed at 4 and 25°C by the batch equilibrium procedure over a broad range of aqueous phase herbicide concentrations. The herbicides showed the following order of increasing tendency to be sorbed: diuron > chlortoluron > bromacil. Sorption constants (Kf) were from 50‐ to 120‐fold higher for the organic soil than for the loamy sand soil, reflecting sorption dependence on soil OC. This variation in Kf was reduced to less than twofold variation in Koc by normalizing sorption to OC. Although sorption was higher at 4 than at 25°C, the difference was only minor at this temperature range. The isosteric heats of sorption (δHs) were relatively small and exothermic, suggesting the involvement of entropy driven mechanism. Water solubility (S) and octanol‐water partition coefficient (Kow) of the herbicides were determined and used to derive equations for estimating Koc with r2 ≥0.989. The practical utility of these correlations is that they allow reasonable estimates of Koc from more easily determined molecular parameters.