bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Soil Thickness on Nitrogen Distribution and Use by Crested Wheatgrass
Authors: Power J. F. , Merrill S. D. , Smith S. J. 
Published: July 2010

AbstractSoil thickness can affect nitrogen (N) cycling and use in several ways, particularly if the solum contains materials restrictive to root growth. Microplots of 0.093 m2 were established on a reconstructed mine soil composed of 0.2 m A horizon (Haploborolls) over 0.05, 0.30, 0.55, or 0.80 m of B and C horizon material spread over sodic (SAR 29.5) minespoil, giving soil thicknesses of 0.25, 0.50, 0.75, and 1.00 m, respectively. The area had previously been seeded to crested wheatgrass (Agropyron desertorum var. Mandan) and fertilized annually with 55 kg N ha−1. In spring 1978, the grass on eight microplots received enriched (27.5%) K15NO3 at 48.6 kg N ha−1. Grass on 16 other microplots harvested in 1979 and 1980 also received enriched 15N fertilizer in late November 1978 and commercial ammonium nitrate (NH4NO3) (50 kg N ha−1) in November 1979. After harvest in each of the 3 yr, soil in the eight microplots was excavated, and 15N enrichment in forage, roots, and soil organic N was determined. Increased soil thickness greatly increased forage and root growth, but had much less effect on N concentration in plant material. Uptake of labeled N in neither forage nor roots was greatly influenced by soil thickness, either in the year of application or the following year. Uptake of labeled N in forage the 2nd yr was only 5 to 10% of that found the 1st yr. However, uptake of soil N in both forage and roots generally increased two‐ to threefold as soil thickness increased from 0.25 to 1.00 m. Soil inorganic N and forage N concentrations suggested that available N supply was not limiting. Thus, the increase in soil N uptake probably resulted from deeper and more effective root functioning with increased soil thickness. Approximately 35% of the labeled N applied was removed in harvested forage and 12% remained in roots, regardless of soil thickness. However, the quantity of labeled N immobilized as soil organic N varied from over 40% of that applied with 0.25‐m soil thickness to about 30% for 1.00‐m thickness. Because there was no runoff or leaching, this difference was probably due to gaseous losses, possibly by ammonia volatilization from plant material.
Spatial Variability of Hydraulic Properties in the Emporia Series
Authors: Albrecht K. A. , Logsdon S. D. , Parker J. C. , Baker J. C. 
Published: July 2010

AbstractVariability of soil hydraulic properties of one soil series is evaluated, observation scale effects are analyzed, and sampling requirements for series characterization are determined. One site was selected in each of four counties. Every site had four subsites about 30‐m apart. Undisturbed cores were taken in triplicate about 0.3‐m apart at each subsite and disturbed samples taken in single replicate within sampling pits at each subsite. Three depths were examined—the A, E, and Bt horizons. Coefficients of variation (CV) for moisture retention data were low ranging from 1.0 to 15.4%, while CVs of saturated hydraulic conductivities (Ks) ranged from 112 to 297%. Nested analyses of variance revealed that variance generally increased with increasing sample separation distance. The majority of the variance occurred at the site level. Numbers of samples needed to estimate means to selected confidence levels for series characterization were determined for each parameter by depth. Assuming costs to be equal between sites, subsites, and replicates, it was found that 10 to 26 sites with one subsite per site and one replicate per subsite should be sampled to adequately describe moisture retention to within 0.05 m3 m−3 and 7 to 15 sites would be necessary for Ks evaluation to within one order magnitude. Results emphasize the need to sample many sites for hydraulic properties which have most of their variance at this level.
Computer Simulation of Water Drop Impact in a 9.6‐mm Deep Pool
Authors: Ferreira Alfredo G. , Larock Bruce E. , Singer Michael J. 
Published: July 2010

AbstractThe interaction between impact of a 3.2‐mm drop and a water layer over the soil surface was studied by simulating drop impact through the solution of the Navier‐Stokes and continuity equations for a viscous and incompressible fluid on an Eulerian grid, using a finite difference method. The simulation was validated by experiments. The velocity field produced by the simulation showed a reversal of the velocity vectors at the time of maximum crater development, followed by crater collapse and formation of the Rayleigh jet. A comparison of measured and simulated crater and crown development showed good agreement. The energy balance from the computer simulation showed that the shear energy development along the bottom of the pool reached a maximum value during the crater collapse when the velocity vectors in the corresponding velocity field were pointing inwards and upwards.
Soil Nutrient Changes Following Whole Tree Harvesting on Three Northern Hardwood Sites
Authors: Mroz G. D. , Jurgensen M. F. , Frederick D. J. 
Published: July 2010

AbstractThree northern hardwood stands were clearcut to evaluate the effect of whole tree harvesting on sites of varying quality. Stands were growing on sandy, outwash soils and had red maple (Acer rubrum L.) site indices of 15, 19, and 20 and biomass values of 114, 165, and 181 Mg ha−1. Harvesting did not alter extractable soil P levels significantly on any site. Forest floor weights decreased to similar values on all sites 1.5 yr after harvest. Nitrogen losses of over 1.3 Mg ha−1 occurred in the top meter of soil on all sites. This was attributed to the mixing of the forest floor with the surface mineral soil by the full tree skidding and the subsequent leaching of mineralized N. Soil exchangeable K decreased more than 1 Mg ha−1 on all sites. Changes in Ca and Mg were much smaller on the low and medium than on the high site. These losses from surface soil horizons are higher than reported previously for clearcutting northern hardwoods on till soils. The greatest impact of whole tree harvest on soil nutrients occurred on the better sites in this study rather than on the poor quality site.
Sodicity Levels of Soils Equilibrated with Wastewaters
Authors: Levy Rachel , Fine P. , Feigin A. 
Published: July 2010

AbstractTo determine the effect of NH+4, K, and Na exchange reactions concurrent with carbonate precipitation on the sodicity levels of soil effluents, samples of sandy, loessial, and clay soils were treated with two wastewaters, a secondary sewage and a liquid sludge. More calcium carbonate (CaCO3) precipitated following the liquid sludge treatment than after the secondary sewage treatment. However, the sodicity levels of the liquid sludge leachates of the three soils were almost unchanged, as compared with that of the wastewater, while those of the secondary sewage increased slightly. It was assumed that this difference was due to the higher concentrations of NH+4 and K found in the liquid sludge as compared with those in the secondary sewage. To verify this assumption, the preference for NH+4, K, and Na of the three soils was evaluated from cation exchange batch experiments; the preference for NH+4 and K was an order of magnitude higher than that for Na. At a given total salt concentration, the sodicity levels decreased as more NH+4 and K substituted for Na. The ionic activity product of CaCO3 which precipitated during the treatments with both waste‐waters had the same value and was higher than that of soil CaCO3. This difference was attributed to the inhibiting effect of the organic residues. The sodicity levels of soils equilibrated with wastewaters were affected both by NH+4 and K exchange and by the higher solubility of the precipitated CaCO3.
Effects of Phosphorus, Sulfur, Calcium Hydroxide, and pH on Growth of Annual Bluegrass
Authors: Varco J. J. , Sartain J. B. 
Published: July 2010

AbstractThe degree of annual bluegrass (Poa annua L.) infestation of turfgrass areas has been observed to be dependent on applied elemental sulfur (S) and phosphorus (P). The purpose of these experiments was to elucidate the effects of P, S, Ca(OH)2, and imbibitional solution pH and acid source on germination, establishment, and clipping yield of annual bluegrass in monoculture. Annual bluegrass was grown in 15‐ by 15‐cm pots filled with Myakka fine sand (sandy siliceous, hyperthermic Typic Haplaquods) in two glasshouse experiments. Treatments for Experiment I were factorial combinations of the following: 0, 250, and 500 kg S ha−1; 0, 40, and 120 kg P ha−1; and 1.5 and 2.0 cmol(+) Ca(OH)2 kg−1. Establishment and average clipping yield responded positively to applied P and Ca(OH)2, while the response to applied S was negative. The magnitude of the response to added P was dependent on S and Ca(OH)2 rates. Conversely, the magnitude of the negative response to S was dependent on P and Ca(OH)2 levels. An optimum tissue P concentration was predicted at 0.52 dag P kg−1 indicating a high requirement for P. In Experiment II, annual bluegrass emergence, establishment, and clipping yield responded in a negative linear fashion to S mixed with the 0‐ to 2.5‐cm soil depth at 0, 50, 100, and 150 kg ha−1. At this soil depth a pH range of 5.6 to 4.3 resulted from these S treatments. These results suggest that annual bluegrass stands can be reduced by acidifying the zone of seed germination using S. Under growth chamber conditions annual bluegrass seed was subjected to acid imbibitional solutions derived from either HCl, H2SO4, or H3PO4 at various pH levels. The first phase was performed at pH levels of 3.0, 4.0, 5.0, and 7.0. Nongermination of annual bluegrass seed was greatest at pH 3.0, but declined rapidly with increasing pH. Abnormal germination or emergence of the plumule only was greatest at pH 4.0 and still evident at pH 5.0. The second phase involved germination of annual bluegrass seed at pH levels of 4.3, 4.8, 5.3, and 7.0. Non‐germination of seed was minimized for this pH range so the decrease in normal germination with increasing acidity was reflected in abnormal germination levels. The decrease in radicle development under high H+ ion concentrations may be due to a loss of membrane integrity and thus, inhibition of cell division in the root tip. Annual bluegrass infestation of turfgrasses may be reduced by limiting P applications and maintaining the soil pH near 5.0, but the infested turfgrass must be tolerant of these conditions.
Soils at Prehistoric Agricultural Terracing Sites in New Mexico: II. Organic Matter and Bulk Density Changes
Authors: Sandor J. A. , Gersper P. L. , Hawley J. W. 
Published: July 2010

AbstractSoil changes initiated by prehistoric cultivation in a semiarid region of southwest New Mexico are still evident about 900 yr after cultivation ceased. Bulk density increases and reductions in organic C and total N were inferred by comparing cultivated soils with nearby, similarly developed uncultivated soils. Comparisons were also made between A horizons and sediment deposits accumulated upslope of recently fallen trees. These deposits are considered analogous to fresh agricultural terrace deposits just prior to cultivation. Depth of cultivation‐induced changes varies but is generally limited to the upper solum. Mean bulk density of cultivated A horizons is 9 and 15% higher than that of uncultivated A horizons and recent sediment deposits, respectively. Cultivated soils are lower in organic C than uncultivated soils by 45, 38, and 32% in the A, BAt, and Bt horizons, respectively. The trend continues through the Bt horizon but is not statistically significant at p < 0.05. Recent sediment deposits tend to be higher in organic C than uncultivated soils and are 54% higher than cultivated A horizons. Total N data give results similar to that of organic C. The significant negative correlation between organic C and bulk density in uncultivated A horizons is not present in cultivated A horizons as values tend to group around a narrower range of lower organic C and higher bulk density values. The long‐term degradation of these cultivated Mollisols is attributed to their sensitivity to disturbance.
Derivation of Land Qualities to Assess Environmental Problems from Soil Surveys
Authors: Breeuwsma A. , Wösten J. H. M. , Vleeshouwer J. J. , van Slobbe A. M. , Bouma J. 
Published: July 2010

AbstractA digitized soil map with scale 1:50 000 of a sandy area of 2000 ha in the Netherlands was used to derive interpretive maps showing gradations of three land qualities of importance in assessing environmental problems. An interactive graphics computer system (IGS) was used. The land qualities calculated from soil properties of the unsaturated zone were: (i) travel times of water, (ii) cation exchange capacity (CEC), and (iii) phosphate sorption capacity (PSC). Transfer functions were defined, relating soil characteristics (texture, organic matter content, and oxalate‐extractable Al and Fe, integrated across horizons designation) to the land qualities. Water‐table levels were defined in terms of the mean highest (MHW) and the mean lowest (MLW) levels. Land qualities were expressed in terms of classes that spanned the range of observed spatial variability. The IGS system can produce interpretive maps from the soil map almost instantly, given selected inputs such as specified water‐table levels.
Factors Affecting the Stability of Soil Crusts in Subsequent Storms
Authors: Levy G. , Shainberg I. , Morin J. 
Published: July 2010

AbstractConflicting results exist concerning the effect of drying on the properties of soil crusts. In this study the hypothesis that the stability of crust to drying depends on the processes that predominate during its formation was tested by studying the effect of application of distilled (DW) and saline water (SW) (EC = 5 dS m−1) on the infiltration rates (IR) of a crusted soil surface. A Typic Rhodoxeralf and a Calcic Haploxeralf saturated with low (< 3.5) and high (17 < ESP < 20) exchangeable sodium percentages (ESP) were exposed to simulated rain of low and high energy levels. The soils were oven‐dried at 35°C for 24 and 72 h between consecutive storms. The stability of the crust was found to depend on the mechanisms of its formation. The crusts of soils with low ESP exposed to DW and SW rain and the crust of a soil with high ESP exposed to SW rain were found to be unstable and to be affected strongly by (i) the salinity of the rain water in subsequent storms, (ii) the impact energy of the raindrops, and (iii) the length of the drying period between consecutive storms. Conversely, a crust in which chemical dispersion supplemented physical dispersion (a soil with high ESP exposed to DW rain) was found to be stable and to be less affected by the water salinity of the subsequent storm, by its impact energy, or by the extent of drying between storms.
Evaluating Mineral Dissolution in Laboratory Weathering Experiments Using Leachate Equilibria
Authors: Sullivan Patrick J. , Sobek Andrew A. , Rybarczyk James P. 
Published: July 2010

AbstractA laboratory mineral weathering study was completed using pyrite and soxhlet leaching apparatus to demonstrate the application of the GEOCHEM computer model for identifying mineral weathering reactions from nonequilibrium leachates. Crushed crystals of pyrite were continuously leached at approximately 27°C for 144 h. Every 24 h, leachate was removed from the soxhlet and analyzed for pH, ferric Fe, ferrous Fe, SO2‐4, Ca, Mg, and silica. Based on the stoichiometry of pyrite oxidation, the GEOCHEM computer model was utilized to calculate leachate pH. By comparing the GEOCHEM calculated pH to the observed leachate pH, it was determined that pyrite oxidation in the soxhlet occurs through a reaction with atmospheric O2 and not with ferric Fe. The results of this study exemplifies the use of geochemical models to help identify and characterize weathering reactions under conditions of nonequilibrium.
Determination of Saturated Hydraulic Conductivity from Soil Percolation Test Results
Authors: Fritton D. D. , Ratvasky T. T. , Petersen G. W. 
Published: July 2010

AbstractPercolation times and saturated hydraulic conductivity rates from 28 test holes were used with data from the literature to relate saturated hydraulic conductivity, K, to percolation time, P. Sites were chosen to represent seven central and western Pennsylvania soils developed in shale and sandstone colluvium, alluvium, glacial outwash, or residual limestone parent materials. Saturated hydraulic conductivity was determined by the shallow well pump‐in method, an in‐situ test that measures three‐dimensional water flow into the soil. Percolation time was determined using a modification of approved procedures of the Environmental Protection Agency and the Pennsylvania Dep. of Environmental Resources. Linear regression analysis performed on the base 10 logarithm of the 28 pairs of data from this study resulted in the equation: log K = −0.309 log P −4.296 (with P in units of s/m and K in units of m/s). This equation was compared to an equation derived from literature data and to a steady‐state three‐dimensional infiltration equation derived from soil‐water flow theory. It was concluded that the literature data and the theoretical equation were different from that generated in this study due to the use of a saturated hydraulic conductivity technique that was sensitive to the layered nature of the soils used. It was further concluded that an equation derived from theory, log K = ‐log (P) − log (1 + 4/παro), could be used to convert percolation times, P, to saturated hydraulic conductivity values, K.
Symbiotic and Free‐living Denitrification by Bradyrhizobium japonicum
Authors: Smith Geoffrey B. , Smith M. Scott 
Published: July 2010

AbstractDenitrification by Bradyrhizobium japonicum (formerly Rhizobium japonicum) was characterized in two strains, USDA‐110 and USDA‐23, to determine the extent of denitrifying enzyme expression during symbiotic growth with soybean [Glycine max (L.) Merr.]. The rhizobia grew in anaerobic batch cultures, depleting NO3‐ and producing N2O in the presence of C2H2. Specific denitrifying activities of resting cells of rhizobia were compared with those of the common soil denitrifier Pseudomonas fluorescens, and were found to range from 14 to 18% of the P. fluorescens activity. Bacteroid specific activities were less than activities of free‐living rhizobial cells, though the ratio depended on the growth stage of the cells. Denitrification was observed in detached whole nodules containing either of the strains, but not in nodules formed by a NO3‐ reductase mutant of B. japonicum 110. Denitrification rates of nodules were unaffected by the presence of external O2, though the rates were limited by the external NO3‐ concentration. Denitrification by intact, nodulated soybean plants under aerobic conditions was observed. In the presence of NO3‐ denitrification and N2 fixation (C2H2 reduction) occurred simultaneously. The estimated ratio of N denitrified to N fixed ranged from 0 to 0.3, depending on assay conditions. The observations suggest that denitrification in soybean nodules in the field can be a continuous process, independent of soil aeration. However, it is likely to be slow relative to N2 fixation under most conditions.
Soil and Slash Pine Response to Sludge Applications in Florida
Authors: Lutrick M. C. , Riekerk H. , Cornell J. A. 
Published: July 2010

AbstractA study was made of the mineral uptake by slash pine (Pinus elliottii Engelm.), and of the movement of nutrients through the profile of an extremely sandy soil to which liquid digested sewage sludge containing 26 g kg−1 (2.6%) solids had been applied as a source of plant nutrients. The sludge was applied only once to an area planted to pine seedlings, at rates of 0, 20, 40, 60, 80, and 100 Mg ha−1 dry matter. The large amount of N (730‐3650 kg ha−1) in the sludge treatments would limit the amount of sludge that would be applied to slash pine grown on a Troup fine sandy loam (Grossarenic Paleudults), since NO3‐ could leach into the ground water if sludge were applied in excessive amounts. Large amounts of P and Zn also were added to the soil from the sludge, but neither moved down the soil profile beyond the 90‐cm sampling depth. After 4 yr of growth, the N and P concentration in pine needles had increased significantly from the sludge treatments, but after 8 yr, the N and P concentration in needles was not significantly different among treatments. However, the Ca concentration in the pine needles increased due to treatment after 8 yr but was not different after 4 yr. Addition of sludge increased individual tree growth by 0.8 dm3 yr−1 and increased annual yield by 1.0 m3 ha−1 per 10 Mg ha−1 sludge. Annual yields were probably diminished because the addition of sludge to the planted pines caused some damage and mortality. A deep sand of low fertility, such as this Troup fine sandy loam, would respond better to an application of −10 to 20 Mg ha−1 yr−1 of sludge over a 2‐ to 3‐yr period.
Incorporation of 35S‐sulfate Into Inorganic and Organic Constituents of Two Forest Soils
Authors: Schindler S. C. , Mitchell M. J. , Scott T. J. , Fuller R. D. , Driscoll C. T. 
Published: July 2010

AbstractIncorporation of 35S‐sulfate into phosphate‐extractable S, hydriodic acid‐reducible S (HI‐S), and total S was measured in three horizons of Spodosols from the Huntington Forest, New York and Hubbard Brook Experimental Forest, New Hampshire. After 56 d 35S incorporated into nonwater‐extractable S constituents was 92, 65, 92, 63, 72, and 91% of the total 35S‐activity for the Huntington Forest Oa, Bh, Bsl, and Hubbard Brook Oa, Bh, and Bsl horizons, respectively. Immobilization of 35S‐sulfate into carbon‐bonded S (total S — HI‐S) was the major incorporation pathway in the Oa horizons. Adsorption of 35S‐sulfate (phosphate‐extractable) was most evident in the Bh and Bsl horizons. Incorporation of 35S‐sulfate into ester sulfate (HI‐S — inorganic S) occurred in all horizons. The influence of immobilization‐mineralization and adsorption‐desorption on S dynamics of these forest soils was evaluated.
Neutron Moisture Meter Calibration for Minespoils Containing Coal
Authors: Halvorson Gary A. 
Published: July 2010

AbstractLaboratory calibrations were used to determine the effect of coal in spoil on neutron moisture meter measurements. Calibrations were conducted on clay loam and loamy sand minespoils from western North Dakota, with and without coal added. Volumetric water contents were overestimated by 3.7% in clay loam containing 8% coal by weight, and 4.7% in loamy sand containing 9% coal by weight using a calibration curve based on similar material without coal. The equivalent water content of the coal (θc) was calculated from the H content of the coal. Correction of calibration curves containing coal by adding θc to volumetric water contents substantially accounted for differences between calibration curves with and without added coal. Due to the large variability in both concentration and size of coal fragments in minespoil, accurate calibration is difficult at best. Since the slope of the calibration curve is unaffected by the presence of coal, changes in soil‐water content over time can be accurately determined from one calibration curve. At sites containing coal fragments, absolute measurements of soil‐water content are difficult, and therefore, only relative differences in water content over time should be determined.