bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of Solution Composition on Sorption of Zinc by Soils
Authors: Elrashidi M. A. , O'Connor G. A. 
Published: July 2010

AbstractThe effect of soil solution composition on Zn sorption was investigated in nine soils of varying physical and chemical properties. Most of Zn applied in 0.01 N CaCl2 solution was strongly sorbed by the soils and desorption by 0.01 N CaCl2 solution was negligible even after five desorption cycles. At initial Zn solution concentrations of ⩽ 10 ppm, sorption could be described by the Freundlich sorption isotherm equation. Deviations from this equation were observed at higher concentrations, suggesting the presence of more than one type of site or mechanism for Zn sorption in the soils.The effects of anion species (Cl‐, NO‐3, and SO2‐4) and ionic strength on Zn sorption were examined at anion concentrations of 0.005, 0.02, and 0.1M. Complexation of Zn (as ZnSO04) in the SO2‐4 system was higher than in either the NO‐3 [Zn(NO3)+] or Cl‐ [Zn(Cl)+] system. However, under the experimental conditions examined, neither ionic strength nor anion complex formation significantly affected Zn sorption.The presence of EDTA (Ethylenediaminetetraacetic acid) in the soil suspension significantly decreased Zn sorption by the three soils investigated. Only a slight difference in Zn sorption was observed whether EDTA was added to the (Zn containing) soil solution before or after contact with soil.The influence of Ni and Cu on Zn sorption was significant only when metal concentration in the soil solution was in excess of the sorbing capacity of the soil. In this case, Cu was more effective than Ni in decreasing Zn sorption.
Influence of Salinity on Soil Enzyme Activities
Authors: Frankenberger W. T. , Bingham F. T. 
Published: July 2010

AbstractEfforts were made to assess the levels of soil enzyme activities that have a specific role in the N, C, P, and S cycles of saline soils. Fieldmoist soil samples were treated with four rates of CaCl2, NaCl, and Na2SO4 solutions applied to produce electrical conductivity readings of saturation extracts (ECe) ranging up to 22 mmho/cm. The range of ECe values included threshold salinity levels associated with reduced yields of agronomic crops. After 7 d of equilibration, the following soil enzymes were assayed: amidase, urease, acid phosphatase, alkaline phosphatase, phosphodiesterase, inorganic pyrophosphatase, arylsulfatase, rhodanese, α‐glucosidase, α‐galactosidase, dehydrogenase, and catalase.Soil enzyme activities decreased with increasing ECe; however, the degree of inhibition varied among the enzymes assayed and the nature and amounts of salts added. Dehydrogenase activity was severely inhibited by salinity, whereas, the hydrolases showed a much lesser degree of inhibition. Generally, the inhibition of soil enzyme activities by the salt solutions decreased in the following order when compared at the same ECe level: NaCl > CaCl2 > Na2SO4. Reduced enzyme activities in saline soils may be due to the osmotic desiccation of microbial cells releasing intracellular enzymes which become vulnerable to attack by soil proteases, a “salting‐out” effect modifying the ionic conformation of the active site of the enzyme‐protein, and specific ion toxicities causing nutritional imbalances for microbial growth and subsequent enzyme synthesis.
Graphical Diagnoses of Lodgepole Pine Response to Fertilization
Authors: Weetman G. F. , Fournier R. 
Published: July 2010

AbstractA combined use was made of “mini” plots and graphical analysis of shifts in nutrient concentration, unit fascicle weight, and nutrient content for needles grown in the first year following spring fertilizer application. Nitrogen, phosphorus, and potassium were applied, in factorial design with five replications, to 17 precommercially thinned lodgepole pine stands in the interior of British Columbia.The use of one bulked foliage sample from two sample trees per plot was sensitive to treatment differences. Phosphorous, potassium, calcium, and magnesium deficiencies were generally not diagnosed either with or without N additions. Mean fascicle weight increase for all trials was 20% for three N levels, suggesting a strong probability of appreciable 5‐year volume increases. Response to N additions was variable and could not be readily explained by site conditions. Non‐responsive stands showed luxury N uptake and suggested the presence of non‐nutritional growth constraints. Additional screening trials are recommended to sample the wide range of sites and climates. The technique was found to be time and cost efficient with the advantage of producing both response data and nutrient status diagnosis within 1 year of fertilizer application.
Modified Soxhlet Extractor for Pedologic Studies
Authors: Sobek A. A. , Bambenek M. A. , Meyer D. 
Published: July 2010

AbstractThe soxhlet apparatus has been used in the laboratory to stimulate geochemical weathering; however, the high extraction temperatures required in the soxhlet do not represent a realistic simulation of the weathering environment. A modified design of the original soxhlet did not eliminate the problems of extraction temperature or inaccurate volumes of solvent passing through the sample. These problems were solved by moving the extraction chamber away from the upward path of the refluxing solvent. Extraction temperature differences (approximately 52°C) were responsible for higher concentrations of leachate metal in the original soxhlet leachate when a minesoil sample was weathered. This modification permits exact volumes of solvent to be passed through the sample, as well as a reduction in extraction temperature that would allow study of the role of bacteria in the weathering process.
A Water Bath System to Observe Temperature Effects on Taproot and Lateral Root Development of Plants
Authors: Stone J. A. , Taylor H. M. 
Published: July 2010

AbstractThis paper describes a water bath system designed to provide accurate root‐zone temperature control and serial observation of taproot and lateral root development to a depth of 120 cm. The system consists of a 137.2‐ by 100.3‐ by 121.9‐cm deep constant‐temperature water bath, 12 2.5‐ by 30.5‐ by 121.9‐cm immersed acrylic plastic plant‐growth containers, movable lighting, and a derrick for removing the growth containers. The acrylic containers are lifted from the bath in tiers of three, and data recorded with photographs.Temperature distribution within the bath has been measured at water temperatures ranging from 5 to 35°C and in the acrylic containers at water temperatures ranging from 17 to 29°C. Temperatures remained within ±0.3°C of the setting throughout the water bath for 25 d with no detectable spatial variability. Temperature gradients within the acrylic growth containers are presented.
Shear Resistance Enhancement of 1.22‐Meter Diameter Soil Cross Sections by Pine and Alfalfa Roots
Authors: Waldron L. J. , Dakessian S. , Nemson J. A. 
Published: July 2010

AbstractPlant roots have been shown to increase soil shear resistance through direct mechanical reinforcement and thereby enhance soil stability on slopes. Because of their potential large diameter and length, the roots of trees may be especially significant in such soil reinforcement. To provide large rooting volumes simulating natural conditions and shear cross sections many times larger than potential tree root diameters, we constructed 12 1.22‐ by 1.22‐m cylindrical soil containers in which two artificial soil profiles were prepared. Replicates of each profile type were planted to alfalfa, yellow pine, or were kept clear of plants. A large pneumatic direct shear device sheared both root‐free and root‐permeated materials along a horizontal plane at the 0.6‐m depth at either constantly maintained shear stress levels (creep shear) or at constant shear displacement rates.Creep shear at the 0.6‐m depth showed that roots of 14‐month‐old alfalfa increased the shear resistance of homogeneous clay loam and a clay loam/gravel interface simulating a soil‐weathered rock boundary by 32 and 50%, respectively. Constant shear displacement rate experiments at the same depth on similar samples permeated by roots of yellow pine planted 54 months earlier showed shear resistance increasing steadily with displacement over the entire test displacement range. At 75 mm displacement, the shear resistance of the pine‐rooted soil was about two times that of the nonrooted in both profile types. The superiority of pine roots to alfalfa roots in increasing soil shear strength in these experiments is in accord with field observations that woody plants are more effective than herbaceous plants in stabilizing soil against slips and slides. Pine root‐size distributions determined 11 months after the last shear test were combined with root tensile strengths and Young's moduli previously measured and used in model simulations of root reinforcement with good results.
Kinetic Properties of L‐Histidine Ammonia‐Lyase Activity in Soils
Authors: Frankenberger W. T. 
Published: July 2010

AbstractEnzyme kinetic analyses were performed to characterize the L‐histidine ammonia‐lyase‐catalyzed reaction in soils. The velocity curves of soil L‐histidine NH3‐lyase as a function of substrate concentration displayed sigmoidicity. The apparent [S]0.5 values of this enzyme in eight soils ranged from 26 to 41 mM (avg = 32 mM) and the apparent Vmax values ranged from 51 to 97 µg NH4‐N released·g of soil−1·48 h−1. The velocity of this enzyme was described by the Hill equation which measures the deviation in hyperbolicity of saturation curves. The experimental data yields strong cooperativity in terms of the Hill coefficient (napp = 4.0 to 5.5) and shape of sigmoidicity ([S]0.9/[S]0.1 = 2.2 to 3.0). The Ea (activation energies) and Q10 values for the L‐histidine NH3‐lyase catalyzed reaction in seven soils at temperatures below inactivation (< 60 °C) ranged from 37.0 to 65.4 kJ/mol and 1.51 to 2.58, respectively.
Growth and Survival of Cowpea Rhizobia in Acid, Aluminum‐Rich Soils
Authors: Hartel Peter G. , Alexander Martin 
Published: July 2010

AbstractA study was undertaken to determine whether Al‐sensitive cowpea Rhizobium survives in acid, Al‐rich soils. The lower pH limit for growth of 20 strains in a defined liquid medium varied from pH 4.2 to less than pH 3.6. The mean lower limit for growth was pH 3.9. Several of the strains clumped in this medium at pH 4.5. Of 11 strains that were tested for tolerance to high levels of Al in a defined liquid medium at pH 4.5, nine tolerated 75 µM Al, and the other two were sensitive to levels above 15 µM. Three strains, one Al‐tolerant, one Al‐sensitive, and one Al‐tolerant or Al‐sensitive depending on the presence of vitamins in the medium, were selected for studies in Al‐rich sterile and nonsterile soils. These rhizobia did not survive in soils of less than pH 4.7 sterilized by 60Co irradiation. When inoculated into sterile soil at pH 4.7, the consistently sensitive strain initially failed to proliferate and then grew slowly, but populations of the other two rhizobia increased rapidly. No consistent relationship was found between the Al tolerance of these three rhizobia and their growth and survival in four acid, Al‐rich soils. The data suggest that Al is of minor importance to growth and survival of cowpea Rhizobium strains in acid soils.
Micromorphology of some Chernozemic Soils with Grumic Properties in Saskatchewan, Canada
Authors: Mermut A. R. , St.Arnaud R. J. 
Published: July 2010

AbstractTwo clayey soils (Indian Head and Balcarres Associations) and two fine loamy soils (Swinton and Weyburn Associations), all currently classified under the Chernozemic order (Borolls), were used in this study to establish the micromorphology of soils with grumic properties. Micromorphometric analyses consisted of fabric classification and estimation of void types, skeleton grains, and plasmic fabric by a point counting method. Basic plasmic fabric, plasma separations, and pedological features separate the clay soils from the two other Chernozemic profiles. The clayey soils have produced entirely different void patterns with a majority of planar voids, suggesting stress phenomena in these soils. The presence of soil nodules partly incorporated into the f‐matrix which is considered to be strong evidence of a churning process and especially the fraction of masepic plasmic fabric in the total plasma are in good agreement with void and related distribution pattern characteristics indicating a dynamic layer of up to 1 m in thickness within the two clayey profiles. Aside from the climatic parameters, these soils are very similar to Vertisols. The study signifies the necessity to reconsider the classification of such soils.
Amides as Sources of Nitrogen for Plants
Authors: Cantarella H. , Tabatabai M. A. 
Published: July 2010

AbstractAmidase activity was detected recently in soils. This enzyme catalyzes the hydrolysis of aliphatic amides to NH3 plus their corresponding carboxylic acids. The activity of this enzyme in soil deserves special attention because its substrates are potential N fertilizers. In this study, six amide compounds (formamide, acetamide, 2‐cyanoacetamide, glycinamide, oxamide, and azodicarbonamide) were tested in a greenhouse experiment for their N‐supplying potentials to plants, compared with those of two conventional N fertilizers (ammonium nitrate and urea). Annual ryegrass (Lolium multiflorum Lam.) was used as the indicator plant. Ryegrass was grown on three soils (Storden, Fayctte, and Clarion), treated at the rates of 0, 240, 480, and 720 mg N/pot (3 kg of soil) and harvested four times at 1‐month intervals. With all the N sources tested, the dry matter yield increased with increasing the rate of N application on Fayette and Clarion soils. The results were inconsistent with the sandy Storden soil. Statistical analysis (Duncan's Multiple Range Test, P = 0.05), showed that the total dry matter yields obtained with formamide, glycinamide, 2‐cyanoacetamide, and oxamide were not significantly different from those obtained with urea and ammonium nitrate at the three rates of N application on Fayette and Clarion soils and at the 480 mg N/pot rate on Storden soil. The total dry matter yields obtained with acetamide tended to be lower than those obtained with the other N sources at the three N rates on Fayette soil and at the highest N rate on Clarion soil. The results with azodicarbonamide always were significantly lower than those obtained with the other N sources tested. Expressed as a percentage of the N applied, the total N uptake from azodicarbonamide was significantly lower than those obtained with the other N sources studied. Considering all the N sources and rates of N application, dry matter yield was significantly correlated with N uptake from all three soils, indicating that the effectiveness of a unit quantity of N taken up by ryegrass in increasing the dry matter yield was similar among the amides and conventional fertilizers in this study.
Biological Cycling of 15N‐Labeled Fertilizer Nitrogen in Lignite Minesoil Materials
Authors: Chichester F. W. , Smith S. J. 
Published: July 2010

AbstractSoil profile and overburden core materials from a lignite minesite in east central Texas were amended with 15N‐labeled Ca(NO3)2 fertilizer and cropped to forage grasses in the greenhouse to determine their relative potential for supporting an active biological N cycle. Soils and overburden materials were sampled before and after cropping and analyzed for distribution of total N and fertilizer 15N in various chemical compartments. Several soil properties which affect N cycling were also measured. Plant tops from several harvests plus roots and crowns from the final harvest were analyzed for total N and 15N content. Results were compared among soil and grass treatment combinations, for uncropped and cropped samples, to determine any differences in N behavior, particularly between surface (A horizon) soils and subsurface strata materials. Nitrogen fertilizer recovery by plants averaged 65% of that applied. Approximately 21% of 15N was unaccounted for and assumed lost through denitrification by the end of the cropping period. There were no significant differences in either measurement due to soils or grasses. There were significant differences (p = 0.05) in amounts of 15N remaining in soils after cropping. Total indigenous soil N was composed of chemically more stable organic forms in the subsurface materials, with generally higher C:N ratios than in the surface soils. Distribution of the more recently‐incorporated fertilizer 15N among soil N forms was similar in surface and most subsurface materials, with a greater proportion found in chemically less stable forms. The acid lignitic clay was the one exception in that 15N distribution within the acid‐soluble fractions was different from that of other soils.The amount of indigenous soil N mineralized during aerobic incubation was significantly greater in surface than subsurface samples, measured either before or after cropping. Percent mineralization of immobilized fertilizer 15N was greater on the average than that of total soil N residual. The relative amounts of 15N mineralization among soils was no different, however, than that for indigenous soil N, even though the 15N was similarly incorporated into less stable forms in each. Apparently differences in the C:N ratio were strongly determinant of differences in 15N disposition observed among soils. The measured tendancy for the C:N ratio to decrease with cropping demonstrated the potential to increase N incorporation and cycling through proper fertilizer management on minesoils constructed from materials evaluated in this study.
Soil Solution Composition as Affected by Liming and Incubation
Authors: Curtin D. , Smillie G. W. 
Published: July 2010

AbstractSamples of three acid soils were limed with CaCO3 and incubated at approximately field capacity moisture content. Soil solution samples were obtained by miscible displacement at intervals of 1, 5, 27, and 52 weeks after liming. The rapid influence of added CaCO3 was shown by the large increases in soil solution pH, Ca, and HCO3 found 1 week after liming. Other effects of liming included increases in soil solution NO3 and organic matter, and reductions in K and Si. The activities of the major cations (Ca, Mg, K, and Na) and NO3 increased substantially, whereas pH decreased during incubation. The decline in pH was accompanied by increases in Al, Mn, and Zn in solutions obtained from unlimed soils. The changes with time were apparently due to liberation of protons along with NO3 into soil solution as a result of organic matter mineralization. Basic cations were displaced from exchange sites by protons, while Al, Mn, and Zn were released into solution as the acidity of the system increased. Logarithims of activities of Al3+, Mn2+, and Zn2+ were linearly related to solution pH. These relationships were such as to suggest that the mechanisms controlling the solubilities of these ions were similar in each soil. The solubilities, however, were not consistent with published solubilities of any common minerals. A tendency for solubilities to be comparatively high at higher pH may be an indication that soluble organic complexes were underestimated.
Soils on Terraces Along the Cauca River, Colombia: I. Chronosequence Characteristics
Authors: Alexander E. B. , Holowaychuk N. 
Published: July 2010

AbstractSoils on two floodplain and six terrace levels, developing under lowland tropical evergreen or semideciduous forest before recent deforestation, were studied to determine the properties found to vary most with relative age. They are in a sequence from a Typic Tropaquent and an Aeric Tropaquept on the two floodplain levels through Haplustults and Paleustults to a Tropeptic Haplustox on the highest terrace. The soil properties may be placed into three categories based on their variations with relative soil age. (i) Soil properties which are similar in all of the terrace soils are bulk density, clay content in the B horizons, 15 bar water retention, organic C content, and dithionite‐citrate‐extractable Fe. Differences in soil morphology are small, other than the relative thinness of the solum in the soil on the lowest terrace, an anomalous (with respect to age) hardpan in the soil on the next terrace, and slightly higher chroma in the soils on the two highest terraces. (ii) The proportions of different exchangeable cations exhibit age trends in the younger (lower) terrace soils but are either similar in the older (higher) terrace soils or so erratic that an age trend is not apparent. (iii) Except for properties of the clay fractions, only the extractable Fe ratio (Feo/Fed) was found to vary systematically through the entire sequence of terrace soils. It decreases from slightly > 0.4 in the lower floodplain soil to < 0.01 in the lower solum of the oldest soil.
A Numerical Study of Raindrop Impact Phenomena: The Elastic Deformation Case
Authors: Huang C. , Bradford J. M. , Cushman J. H. 
Published: July 2010

AbstractUnderstanding the deformation processes of soil material under raindrop impact is a basic step in studying soil resistance against particle detachment by raindrop splash. To simulate the deformation pattern of a solid material under impact, we used the finite difference technique to solve the dynamic equation of linear elasticity. The selected material properties resembled soil media of wide ranges of elasticity. Two types of impact loading were imposed: a steady, uniform load and a simulated raindrop impact load. Materials responded differently under these loading conditions and showed dissimilar deformation patterns. For a material with low modulus of elasticity, a uniform depression was found under steady, uniform load, while a cone‐shaped depression was shown under simulated raindrop impact. The shape of the surface deformation gave us insight into the mechanism of material detachment. The interaction of the lateral jet stream and the obstacles in its course are believed to be the major factor in determining the material detachment. The obstacles can be the sides of the cavity or the irregularities on the granular material itself.
Zinc and Copper Sorption and Interaction in Soils
Authors: Kurdi Fuad , Doner H. E. 
Published: July 2010

AbstractZinc or Cu ion sorption by different soil types conformed to a Freundlich equation but not to a Langmuir equation. Sorption differences among the soils were more related to equilibrium pH than to cation exchange capacity (CEC). Zinc or Cu sorption resulted in release of H and Mn. The release increased with increasing metal ion sorption and was higher with Cu than with Zn. Sorbed Cu was not significantly affected by Zn addition up to 250 µg/mL, though the presence of Cu even at a concentration of 15 µg/mL completely prevented Zn sorption in one soil low in CEC.