bluuebunny/crossref_metadata_2025_split huggingface dataset:
Compositional and Solubility Relationships Between Aluminum‐hydroxyinterlayered Soil‐Smectites and Vermiculites
Authors: Karathanasis A. D. 
Published: July 2010

AbstractCoarse clay fractions (2–0.2 µm) of selected soil samples containing variable quantities (10–52%) of Al‐hydroxyinterlayered smectite (HISM) or vermiculite (HIV) were investigated by XRD, thermal, elemental and solution composition analyses. The HISM vs. HIV nature of the sample was determined from the smectitic or vermiculitic origin of the sample and by alkylammonium ion exchange, expansion with glycerol and resistance to collapse after K‐saturation and heating at 300° and 550 °C. X‐ray diffraction and thermal analysis of tetradecylammonium exchanged clays and structural formulae calculations indicated all hydroxyinterlayered minerals, except for one HISM, to have high layer charge deficiencies (X > 0.5 equivalents per 0.5 unit cell). A greater portion of the total charge deficiency was satisfied by [Al(OH)x]3‐x in HIV minerals which resulted in generally higher free energies of formation (ΔG°f). Hydroxyinterlayered smectites on the other hand, exhibited higher cation exchange capacities and higher OH/Al ratios in the hydroxyinterlayer material. Compositions of soil solutions in contact with these minerals supported a metastable HISM region in relatively Si‐enriched solutions and a metastable or stable HIV region in somewhat Si‐deficient solutions comparable to those supporting the stability of kaolinite. Structural formulae‐ and soil solution‐ compositions of the studied samples appeared to be consistent with the dynamic nature of these minerals in soil environments in terms of mineralogical distribution, physicochemical behavior, and stability.
Mineralization of Phosphorus in Sludge‐Amended Soils Monitored by Phosphorus‐31‐Nuclear Magnetic Resonance Spectroscopy
Authors: Hinedi Zeina R. , Chang A. C. , Lee R. W. K. 
Published: July 2010

AbstractThe purpose of the experiment was to observe the changes occurring in the different phosphorus (P) pools in sludge‐amended soils during incubation using 31P nuclear magnetic resonance spectroscopy (31P NMR) to qualitatively and quantitatively register P transformations. An acid and an alkaline soil were each incubated with sludges that underwent different digestion processes. The 31P NMR spectra of those soils after 1, 28, 70, and 140 d of incubation showed that P diesters completely hydrolyzed after 28 d of incubation in both soils, irrespective of the type of sludge incorporated. After 140 d of incubation, P monoesters were still detected in the acid soil while they had completely hydrolyzed in the alkaline soil. Pyrophosphates were detected after 70 d of incubation in the alkaline soil and 140 d of incubation in the acid soil. The study suggested that acidity has an adverse effect on the microbial degradation of P monoesters and pyrophosphates in sludge‐amended soils.
Nonbiological Nitrous Oxide Production from Vadose Soil Catalyzed by Galvanized Steel Tubing
Authors: Parkin T. B. , Codling E. E. 
Published: July 2010

AbstractStudies of microbial processes in the vadose zone are hampered by difficulties in obtaining uncontaminated samples. We initiated a study in 1985 to quantify microbial denitrification in the vadose zone of agricultural land located in the Atlantic Coastal Plain. In the initial stages of this study, deep soil cores (360 cm) were collected and subcored with sterile galvanized steel tubes to eliminate contamination by surface soil. We observed N2O production from subsoil incubated with C2H2 in galvanized tubes, but in the same soil incubated anaerobically with added glucose and NO−3, denitrification activity was not detected. Subsequent comparisons of N2O production in surface and subsurface soil incubated in galvanized and plastic tubes indicated that chemodenitrification was the likely mechanism responsible for the N2O production observed in soil contained in galvanized steel tubes. These results suggest that, in field or laboratory experiments designed to investigate soil‐N transformations, galvanized steel enclosures should be used with caution.
Denitrification Hysteresis During Wetting and Drying Cycles in Soil
Authors: Groffman Peter M. , Tiedje James M. 
Published: July 2010

AbstractDenitrification response to soil moisture was studied in soils undergoing either wetting or drying cycles to determine if denitrification‐soil water relationships were independent of antecedent moisture conditions. Intact, field moist soil cores were brought into the laboratory and subjected to either wetting or drying phase treatments. In the drying phase treatment, soils were wet to saturation and then progressively dried to field capacity, 60% water‐filled porosity and 20% water‐filled porosity with denitrification measured at each moisture condition. In the wetting phase treatment, soil cores were first dried to 20% water‐filled porosity and were then progressively wet to 60% water‐filled porosity, field capacity, and saturation. Denitrification showed a hysteretic response to soil moisture when drying and wetting phases were compared. In the drying phase, rates of denitrification decreased dramatically as soils were dried from saturation to field capacity, with further decreases in activity observed at 60 and 20% water‐filled porosity. In the wetting phase, denitrification activity sharply increased immediately after rewetting soils from 20 to 60% water‐filled porosity, with only slight increases observed as soils were wet further to field capacity and saturation. The hysteretic response was observed in three soils of markedly different texture. Denitrification dynamics in the wetting phase were strongly correlated with pulses of C and N mineralization caused by stress of microbial biomass by drying and rewetting. Models of denitrification driven by soil moisture need to consider hysteretic effects if they are to accurately predict denitrification activity in the field.
Tillage Effects on Availability of Nitrogen to Corn Following a Winter Green Manure Crop
Authors: Sarrantonio M. , Scott T. W. 
Published: July 2010

AbstractField studies were conducted in 1984 through 1986 to investigate the release of inorganic N to corn (Zea mays L.) following a winter annual green manure crop of hairy vetch (Vicia villosa Roth) that had either been plowed down to 22 cm (conventional tillage, CT), or killed and left on the surface (no‐till, NT). Soil samples were taken regularly throughout the season at three depths (0–7.5 cm, 7.5–22 cm and 22–45 cm) and analyzed for inorganic N. Crop growth and N uptake, as well as various other plant, soil and environmental parameters were also monitored. First year data (1985) show that soil inorganic N concentration in vetch treatments was higher under CT than NT, and it was more evenly distributed throughout the plow layer. Both corn yields and N uptake, however, were significantly higher in the NT system, probably because of higher soil moisture content in a dry summer. Vetch did not stimulate significant yield increases over 0‐N control plots in either tillage system, although there was greater N uptake by corn in vetch treatments. Under NT, 29% of the original N in the above‐ground vetch biomass was measured either as soil inorganic N or corn N. Under CT, 56% of the original vetch N was measured. A repeat of the first experiment was conducted in 1986. Again, higher levels of inorganic N occurred under CT than under NT where vetch had been grown. Contrary to the results of 1985, corn yields were significantly higher in CT treatments than NT treatments at all N levels, and both corn yield and N uptake were significantly higher in vetch treatments than control treatments under both tillage systems. Maximum inorganic N levels were measured in late October in 1986, when 22% and 55% of the original vetch N was measured under NT and CT tillage systems, respectively.
Effect of Zinc Deficiency on Growth, Phosphorus Concentration, and Phosphorus Toxicity of Wheat Plants
Authors: Webb Michael J. , Loneragan Jack F. 
Published: July 2010

AbstractIn some previous experiments, Zn deficiency has enhanced P accumulation in old leaves to toxic concentrations by enhancing the rate of P absorption. This research was undertaken to examine the relationship of Zn deficiency to P accumulation and toxicity in young wheat plants (Triticum aestivum L. ‘Gamenya’) grown in a complete nutrient solution with 1000 µM phosphate and either with or without 2.5 µM Zn. Mild Zn deficiency depressed shoot but enhanced root DM and this change was almost paralleled by P distribution. Severe Zn deficiency enhanced P concentration to 3 to 4% in old leaves and the marked necrotic symptoms were attributed to combined Zn deficiency and P toxicity. It depressed whole plant dry matter (DM) by 40% but P content by only 10%. It severely depressed DM distribution but enhanced P distribution to shoots thus doubling shoot P concentration. Short term and long term estimates indicate that mild Zn deficiency had only a transient effect in enhancing Pi absorption rate as severe Zn deficiency substantially depressed it. Thus, Zn deficiency enhanced P concentrations to toxic levels in old leaves through the cumulative effects of responses at three tiers of structural organization: (i) in the whole plant, it depressed DM more strongly than P content, (ii) between roots and shoots, it depressed that proportion of total DM which was present in shoots while increasing that of total P, (iii) within shoots, it concentrated P in old leaves by depressing new growth.
Evaluation of Soil Variability in Northwest Florida Using Geostatistics
Authors: Ovalles F. A. , Collins M. E. 
Published: July 2010

AbstractThe objectives of this research were to (i) investigate the use of geostatistics in studying the spatial variation of previously statistically selected soil properties in northwest Florida; (ii) have a better interpretation of how the variability in the selected soil properties is related to a physiographic region; and (iii) determine areas where sampling density should be increased. Two sets of data from 151 pedons in a 380‐ by 100‐km irregular grid were used. The sets of data were composed of (i) sand, clay, and organic carbon (OC) contents on a weighted average basis; and (ii) A horizon clay and OC contents. Direction‐independent and direction‐dependent semivariograms were calculated and observed semivariograms indicated drift in the data. Therefore, residuals were used to compute new semivariances. Drift was reduced, but local trends still remained. Semivariograms of sand, clay, and OC contents were anisotropic. Organic carbon content semivariograms exhibited a pure nugget effect indicating a large point‐to‐point variation at short distances and an absence of spatial correlation at the sampling scale used. Kriged data and standard error diagrams of soil properties were related to the five physiographic regions in northwest Florida. The variability shown by these diagrams may be a consequence of the different topography, geology, and management of the area. Reliability (kriged) diagrams were helpful in locating areas of large standard error, such as the northeast edge of the Dougherty Karst physiographic region, that require an increase in sampling intensity to improve the precision of the estimates.
Calciustolls in Central Texas: II. Genesis of Calcic and Petrocalcic Horizons
Authors: West L. T. , Wilding L. P. , Hallmark C. T. 
Published: July 2010

AbstractSoils on hillslopes in the Grand Prairie and eastern Edwards Plateau regions of Texas are developed from multiple facies of interbedded weakly to strongly indurated Cretaceous limestones. Most contain either calcic or petrocalcic horizons. Stable C isotope analysis of the carbonate‐enriched horizons from seven pedons sampled in this area permitted quantification of the amount of pedogenic carbonates. Features indicative of carbonate translocation and accumulation were observed in the soils. However, reconstruction analysis indicated that none of the calcic horizons and few of the petrocalcic horizons contained more carbonates than the parent limestone. Microfabric development in calcic horizons supports loss of carbonates as a major process in these horizons. The pedogenic nature of most of the carbonates in calcic horizons is attributed to in situ recrystallization of the parent limestone. Petrocalcic horizons commonly had areas of strongly indurated limestone in matrix interiors, and micromorphic observations indicated that much of the pedogenic carbonates in these horizons was also the result of in situ recrystallization of the limestone. Petrocalcic horizons occurred on all landscape positions. Their occurrence and position in the profile appears to be related to an indurated limestone bed within the normal depth of wetting. The development of calcic and petrocalcic horizons primarily by recrystallization rather than translocation and accumulation of carbonates contrasts with the commonly accepted model for formation of these horizons.
Chemical, Mineralogical, and Physical Property Differences Between Moderately and Severely Eroded Illinois Soils
Authors: Nizeyimana E. , Olson K. R. 
Published: July 2010

AbstractThe effects of degree of erosion on the chemical, mineralogical, and physical properties of seven Illinois soils were evaluated. At each site, separate map units of moderately and severely eroded phases of a soil series were located in the same field. These paired erosion phases occurred as a consequence of slight differences in slope gradient, slope shape, or slope length within a landscape position. Soil descriptions were made from pits located within each eroded phase of all seven soil series. Soil samples were taken with depth to measure the chemical, mineralogical, and physical properties of each phase of all soil series. The magnitude and direction of change in these parameters varied with soil series. For most soils studied, degree of erosion significantly reduced the organic C, and water storage porosity values of the Ap horizons. Clay mineral type estimates of the Ap horizons of severely eroded soils changed measurably as a result of thinner topsoils permitting the tillage equipment to mix underlying Bt horizon materials higher in hydrous mica or smectite into the topsoil. With increased degree of erosion, pH, cation exchange capacity, K and base saturation value trends varied with soil series. Erosion of soils with root restricting layers, such as dense subsoils, resulted in these layers occurring closer to the surface and in lower profile water storage capacities. Most of the soil property differences between moderately and severely eroded phases of a soil series would reduce the ability of the soil to produce crops. Successful management techniques for the restoration of the productivity of eroded soils will need to modity the chemical, mineralogical, and physical properties of the severely eroded soils.
Reactions of Ammonia and Urea Hydrolysis Products with Soil
Authors: Kissel D. E. , Cabrera M. L. , Ferguson R. B. 
Published: July 2010

AbstractA quantitative description of pH changes in N fertilizer application zones is needed to predict the degree of NH3 formation in the soil solution. In particular, the pH changes following surface application of urea determine in part the degree of NH3 formation and possible loss by volatilization. The objectives of our study were to compare the rise in soil pH following addition of urea and NH4OH to soil, and evaluate the importance of inorganic C reactions to any differences in the rise in pH caused by the two respective N sources. Titration curves with urea or NH4OH as a base were used to determine differences in the patterns of pH change. Up to pH 8.2, soil pH was raised identically by NH4OH and urea that had been completely hydrolyzed. Above pH 8.2, urea was less effective than NH4OH in raising soil pH. The lower effectiveness of urea was due in part to the urea‐C not forming CO2 but remaining as HCO−3 and CO2−3 in the soil solution. Part of the CO2−3 precipitated as CaCO3 when enough urea was added to raise soil pH to 8.8. At a lower application rate of urea, which resulted in a soil pH of 7.15, no CaCO3 was detected. These results demonstrate the importance of inorganic C from urea hydrolysis in providing resistance to a pH increase above pH 8.2 in concentrated fertilizer application zones.
Reversible and Irreversible Dehydration of Hydroxy‐Interlayered Vermiculite from Coastal Plain Soils
Authors: Harris W. G. , Hollien K. A. 
Published: July 2010

AbstractDehydration behavior of hydroxy‐interlayered vermiculite (HIV) from three coastal plain soils was studied using x‐ray diffraction (XRD) and thermal analysis. Relative humidity (RH) at 25 °C had little effect on HIV 001 XRD peaks, except for a 0.01 to 0.05° 2θ shift at RH ≈ 0%. Heating to 50 °C shifted peak positions 0.10 to 0.20° 2θ for fine silts and 0.05 to 0.10° 2θ for coarse clays. Effects of 50 °C treatment were largely reversed by re‐wetting, indicating that H2O re‐entered interlayers. Heating to 115 °C broadened peaks and produced shifts of up 0.40° 2θ. Dehydration at ≥ 115 °C was essentially irreversible, as indicated by lack of 001 expansion and failure to regain full sample weight at 100% RH. Peaks were markedly broadened and attenuated by heating to 165 and 225 °C, with full width at half maxima approaching 1.0° 2θ. No significant peak in the 1.0‐nm region developed from interlayer collapse, even at 550 °C. Reversible dehydration may be attributable to free‐H2O loss from interpolymer zones at temperatures below the onset of significant polymer dehydration. The data suggest that attraction between dehydrated polymers and 2:1‐layer surfaces exceeds hydration forces, resulting in irreversible collapse and variable interlayer thickness. Re‐entry of H2O into interlayers could be sterically impeded by the dehydrated polymers themselves or by their binding effect on layers. The 1.4‐nm mineral in the soils studied exhibits thermal properties more consistent with HIV than an alternative vermiculite‐kaolin intergradient structure.
A Computer Simulation of Fe(III) and Fe(II) Complexation in Nutrient Solutions: II. Application to Growing Plants
Authors: Schwab A. P. , Lindsay W. L. 
Published: July 2010

AbstractA computer model developed by the authors accurately predicted the chelation of ferrous and ferric ion as a function of pH and redox potential in nutrient solutions. Experiments were conducted to establish the apparent redox potential (4 < pe + pH < 7) imposed by roots of efficient and inefficient soybean plants (Glycine max L.). Using this information, equilibrium Fe2+ concentrations were controlled by adjusting the concentrations of the chelating agents. Iron‐59 uptake was correlated with log[Fe2+] for concentrations between 10−6.5 and 10−9.2 mol Fe2+/L in the experimental nutrient solutions.
Edaphic and Reclamation Aspects of Vesicular‐Arbuscular Mycorrhizae in Wyoming Red Desert Soils
Authors: White J. A. , Munn L. C. , Williams S. E. 
Published: July 2010

AbstractThree Aridisols and an Entisol in the Red Desert of southwest Wyoming were surveyed for vesicular‐arbuscular mycorrhizal (VAM) fungal biomass. The survey was conducted to determine attenuation of VAM fungal biomass in profiles of these arid soils, to examine possible edaphic influence on VAM fungal distributions and to evaluate the potential of these soils in providing VAM fungal biomass for use in reclamation. Fungal biomass levels—as indicated by fungal spore densities and bioassay percent infections—was apparently related to morphological and chemical properties that differ between individual soils and their associated vegetation. While fungal spore densities generally attenuated with depth in the Aridisols, the Torrifluvent retained high densities of spores (up to 81 spores g−1 soil) to a depth of 140 cm. The VAM fungal biomass attenuation in relatively deep horizons of these arid soils may still allow adequate formation of propagules for use in reclamation of disturbed lands.
Minirhizotron Installation Techniques for Investigating Root Responses to Drought and Oxygen Stresses
Authors: Box J. E. , Smucker A. J. M. , Ritchie J. T. 
Published: July 2010

AbstractEstimation of plant root activities by the minirhizotron technique is a nondestructive approach for observing root responses to the soil environment, yet few such observations have been made. The purpose of this report is to compare methods for installing minirhizotron tubes in separate experiments located in two regions of the USA. Transparent plastic tubes were installed at acute angles of 0.8 and 1.2 rad to the surfaces of sandy loam (Typic Hapludult and Typic Hapludalf) soils located in Georgia and Michigan. Soil cores were removed from these low expansion‐contraction soils using Giddings hydraulic power samplers. Both ends of the minirhizotrons were stoppered and the aboveground portion of the tube surfaces were made opaque before inserting. The excellent soil to minirhizotron wall interfaces provided clear and high contrast root images that were observed and video recorded. These procedures provided information which indicate that short‐term drought results in root losses near the soil surface and large increases in deep root growth. Uninterrupted O2 stress substantially reduced growth of wheat (Triticum aestivum L.) roots throughout the rhizosphere.
Effects of Soil Flooding on Selenium Transformations and Accumulation by Rice
Authors: Mikkelsen Robert L. , Mikkelsen Duane S. , Abshahi Akbar 
Published: July 2010

AbstractThe fate of Se in flooded soil is not well known. This greenhouse study was conducted to determine the fate of Se in flooded soil and to determine the effects of Se on plant growth. Rice plants (Oryza sativa L. cv. M101) were grown in pots containing Panoche loam soil (fine‐loamy, mixed, calcareous, thermic Typic Torriorthents) to which 0, 1.5, 3, and 6 mg Se kg−1 as Na2SeO4 was added. Rice was grown in continuously flooded or nonflooded (upland) soil. The flooded treatments were amended with organic matter (OM) at concentrations of 0, 2.5, and 5 g cellulose kg−1. Soil solution samples were taken weekly from the flooded treatments and analyzed for pH, Eh, EC, and Se concentration and Se oxidation state. Plants were harvested and analyzed for Se at three plant growth stages. Selenate soil solution concentrations were reduced 95% after 6 and 10 wk following flooding for the 5.0 and 0 g OM kg−1 treatments, respectively. Selenite in solution reached a maximum concentration (340‐1920 µg Se[IV] L−1) 5 to 8 wk after flooding and then decreased to trace levels (<0.5 µg L−1). Selenium accumulated in all rice plant parts in direct proportion to the added Se. Plants grown in flooded soil with added OM had tissue Se concentrations <20% that of rice grown without added OM or in upland conditions. Selenium phytotoxicity symptoms were observed in plants grown in flooded soil without OM and in the upland soil when Se was added. Tissue Se concentrations associated with a 10% reduction in shoot dry matter were 160 and 81 mg Se kg−1 for upland and flooded rice (without added OM). No Se‐induced yield loss occurred when OM was added to flooded soil. Flooding those soils containing Se[VI] may be an effective way to reduce soluble Se concentrations in soil to nontoxic concentrations.