bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ammonia Volatilization from Surface‐Applied Urea: Effect of Hydrogen Ion Buffering Capacity
Authors: Ferguson R. B. , Kissel D. E. , Koelliker J. K. , Basel Wes 
Published: July 2010

AbstractThe influence of soil pH and soil cation exchange capacity on ammonia volatilization from surface applied ammoniacal nitrogen has been reported in previous studies. Since the hydrolysis of ureacontaining N fertilizers causes an increase in alkalinity, a soil's inherent H+ buffering capacity (defined as the soil's total acidity, comprised of exchangeable acidity plus non‐exchangeable, titratable acidity), should exert a dominant influence on the maximum soil pH at the site of urea fertilizer application. The objective of this study was to demonstrate the importance of a soil's H+ buffering capacity in affecting NH3 volatilization from surface‐applied urea. The H+ buffering capacity of two soils was increased by adding hydroxy‐Al polymers to one soil, and weak and strong acid cation exchange resins to the other soil. Care was taken to keep cation exchange capacity and initial pH close to the same on amended and unamended (control) soils. Urea was surface‐applied to amended and unamended soils and ammonia volatilization and soil surface pH were measured. The increase of H+ buffering capacity of soils was found to reduce soil surface pH and NH3 volatilization after application of urea. It is concluded from this work that H+ buffering capacity of a soil is a better indicator of NH3 loss potential than a soil's initial pH.
Soil Structure and Associated Rooting Behavior in Minesoils
Authors: McSweeney K. , Jansen I. J. 
Published: July 2010

AbstractThe objective of this study was to identify and describe soil structural patterns and rooting behavior in reclaimed minesoils. The soil chosen for this study consists of approximately 0.4 m of topsoil (A horizon) material placed on approximately 1.5 m of a blend of B horizon, mixed paleoloesses, Sangamon paleosol, and Illinoian till. Four soil pits were excavated, exposing root systems of the corn test crop. Detailed soil and root pattern descriptions were made in each pit. Root patterns were depicted using the profile wall method. An outline of soil structural pattern was superimposed over the root pattern to provide a pictorial relationship between the two. Differences in the physical condition of subsoils were distinguished on the basis of the soil descriptions and statistical analysis of the root length determinations. An artificial soil structure was characterized and attributed to particular mining and reclamation practices. The structural arrangement consists of rounded aggregates loosely compressed together, that fall within the size classes currently used for blocklike and polyhedral aggregates. Plant rooting was distinctly more profuse where this structure was present than where the soil material was massive and compact. It is proposed that structural differences among newly constructed soils are of such significance that they should be carefully characterized and described, and where appropriate used for series level separations. Operations using a mining wheel in combination with belt transportation favor the formation of the more desirable fritted structure, whereas operations using scrapers exclusively favor the formation of the less desirable massive physical condition.
Micropedological Study of Termite Mounds of Three Species of Macrotermes in Kenya
Authors: Mermut A. R. , Arshad M. A. , St. Arnaud R. J. 
Published: July 2010

AbstractSeven termite mounds built by three Macrotermes species (M. michaelseni, M. subhyalinus, and M. herus) at five different sites were studied micropedologically. Construction units and void patterns were considered as integral parts of mound construction covering specific termite habitats in different eco‐climatic regions of Kenya. Regardless of the species of termites, it was found that the micro construction units recognized in the undisturbed samples taken from different parts of the nests were entirely dependent on the nature of the material form which the mounds were built. Building behavior of different termite species in the same environment appears to be very similar. Different construction units were found to occur in different parts of a mound. The fabric and micromorphological features established in this study consist of pellets, compound pellets, lenticular fabric, mesh fabric, lamellar fabric, organic laminae, cross‐hatched arrangement of ground mass, and mammillated metavughs. The fabrics of the studied mounds were made from transported and repacked soil particles with addition of insect saliva and/or excreta.
Airborne Dusts in the Edwards Plateau Region of Texas
Authors: Rabenhorst M. C. , Wilding L. P. , Girdner C. L. 
Published: July 2010

AbstractAs part of a larger study to estimate the impact of airborne dust on pedogenesis, seven dust traps were installed across a 100 000 km2 region in central and western Texas. Contents of the traps were collected and analyzed at 120‐d intervals. Total annual infall was approximately 12 g/m2 with significant seasonal variations occurring. The average clay content is near 60% and is primarily mica and quartz with lesser amounts of smectite and kaolinite. The medium silt (5–20 µm) comprises approximately 25% of the dust and is dominantly quartz with moderate amounts of alkali feldspars. Particulate carbonates were not observed and Ca values for water from the dust traps indicate that if present, carbonates constitute only a small portion of the total infall. Analyses of medium silt grains using SEM and microprobe indicate that quartz and feldspar grains have both smooth conchoidally fractured surfaces and rough pitted morphologies. Grain surface morphology is not adequate for mineralogical identification. Although some materials from local soils may be collected as dust, analyses indicate that the primary source is external to the study area. Grain morphologies suggest multiple source areas for the dust. Substantial uniformity in total infall, particle size distribution, mineralogy, and silt grain morphology was observed across the study area, indicating that the dust depositions are regional in character.
Influence of Long‐Term Tillage and Crop Rotation on Water Erosion
Authors: Van Doren D. M. , Moldenhauer W. C. , Triplett G. B. 
Published: July 2010

AbstractSoybeans (Glycine max. L.) apparently predispose a field to greater erosion by water than does corn (Zea mays L.) at equal residue cover. Most of the available data have been obtained from locations with 5 years or less history of a specific management. This study measured soil loss during simulated rainfall from plots having an 18‐yr history of management to ascertain deviations, if any, from current expectations. The soil was a fine‐loamy, mixed mesic, Typic Fragiudalfs having an average slope of 3%. Tillage variables included no‐tillage, spring plow 20 cm deep, and spring plow 20 cm deep followed by 10 cm deep disking or equivalent. Rotations were continuous corn or corn‐soybeans. Kinetic energy of applied water was about 70% of natural rainfall at 63 mm/h rate. Runoff and soil loss were measured at 60‐s intervals during the 30‐ to 60‐min runs. Soil loss per unit of rainfall following either crop in the corn‐soybeans rotation was 45% greater than from continuous corn, after accounting for differences in residue cover by use of the Universal Soil Loss Equation (USLE). Soil loss per unit of rainfall for land not tilled for 1 or over 20 years was 90% less than expected according to the current version of the USLE.
Crop Residue Removal and Soil Productivity with No‐Till Corn, Sorghum, and Soybean
Authors: Doran J. W. , Wilhelm W. W. , Power J. F. 
Published: July 2010

AbstractCrop residues have been considered during the past decade as alternate energy sources to supplement dwindling fossil fuel sources and enhance energy independence in the United States. Agricultural scientists have demonstrated the importance of crop residues in reducing soil erosion, enhancing the soil physical environment for plant growth, and as a reserve for major crop nutrients. In eastern Nebraska, we evaluated the effects of various amounts of surface crop residues (aboveground dry matter remaining after harvest) on dry‐land production of no‐till corn (Zea mays L.), sorghum [Sorghum bicolor (L.) Moench], and soybean [Glycine max (L.) Merrill] over a 3‐yr period. Where crop residues were completely removed after harvest, average grain and residue yields of corn and soybean were 22 and 24% lower, respectively, than where residues were not removed. Removal of 50% or addition of 50% (150%) surface crop residues had little or no effect on crop yields compared to no removal (100%).Sorghum yields were unaffected by residue removal, but stands were significantly less at the 150% residue rate. Yield reductions for corn and soybean resulted primarily from decreased soil water storage and excessive surface soil temperatures where residues were completely removed. Sorghum tolerated conditions of temperature and water stress better than other crops. Removal of surface crop residues can seriously reduce corn and soybean yields in climates where stressful conditions occur during the growing season. Considerations for using crop residues as alternate energy sources should include these potential reductions in grain and residue yields, as well as increased nutrient removal and greater potential for soil erosion.
Analysis of Solute Transport in Column Tracer Studies
Authors: Parker J. C. 
Published: July 2010

AbstractTo pose mathematically tractable boundary conditions for finite porous media it is necessary to regard the representative elementary volume (REV) as infinitesimal. In so doing, continuity of macroscopic concentrations across boundaries is in general sacrificed to maintain flux continuity. The macroscopic concentration discontinuity can be rationalized by regarding influent and effluent concentrations as flux‐weighted mean values relative to the volume‐averaged resident concentrations (Cr) in the porous medium near the boundaries. This concept leads logically to the definition of a flux concentration (Cf) defined macroscopically as the ratio of the solute flux density to the fluid flux density. Flux concentrations obey a convection‐dispersion equation of identical form to that for resident concentrations and transformation of boundary conditions allows direct solution for Cr or Cf. Solutions are presented for Cr and Cf for one‐dimensional steady flow which assume back‐mixing at outflow boundaries to be negligible. The solutions are checked against measured effluent curves and resident concentration distributions of Br in a high dispersivity porous medium contrived to have an REV diam (l) of about 25 mm. The solution for Cf accurately describes the breakthrough curve for a 190 mm long column and the solution for Cr matches measured resident concentrations at locations further than l/2 from the boundaries. Solutions which assume equality of Cr and Cf at exit boundaries fail to describe the experimental data. The results indicate that fractured or aggregated porous media having continuous relatively large pores may be treated as simple continua if the flow region is several times larger than the REV.
Steady Infiltration from Spherical Cavities
Authors: Philip J. R. 
Published: July 2010

AbstractThe problem of quasilinearized steady infiltration from spherical cavities, with the moisture potential fixed at the cavity surface, is solved exactly. Solutions are presented numerically and graphically for values of the dimensionless cavity radius R0 in the range 0 to 10. The dependence on R0 of total cavity flow, of the variation of infiltration rate around the cavity surface, and of the distributions of moisture content and potential, are examined. As R0 increases, gravity increasingly distorts the moisture distribution from the symmetry produced by capillarity alone. This distortion, although marked, is less than one‐hundredth that for infiltration from circular cylindrical cavities: a vivid illustration of the stronger dominance of gravity over capillarity in two‐dimensional systems than in three‐dimensional ones. An earlier approximate solution of this problem proves accurate only for R0 ⩽ 0.27. The cavity flow, evaluated by the present analysis, may be combined with the point source solution to give approximate results useful for the region deeper than 20 radii below the cavity.
Curve‐fit Errors in Langmuir Adsorption Maxima
Authors: Harter Robert D. 
Published: July 2010

AbstractAlthough the Langmuir equation does not always adequately estimate “adsorption” maxima, it remains useful for empirical description of data. The test of data fit to the equation has usually been by linearity of the “Langmuir plot,” viz. concentration/adsorption plotted as a function of concentration. This test, however, is inadequate because the plotting of concentration against itself reduces data variability and always provides a statistically significant correlation coefficient. A better test of fit is to ascertain whether the adsorption isotherm has the shape of the equation model. When isotherms do not have the correct shape and only low concentration data is used, the equation can provide estimates of the adsorption maximum that are in error by 50% or more.
A Chemical Model of Phosphate Adsorption by Soils: II. Noncalcareous Soils
Authors: Goldberg Sabine , Sposito Garrison 
Published: July 2010

AbstractThe Constant Capacitance model provided a quantitative description of o‐phosphate adsorption by 44 noncalcareous soils whose pH values ranged from 4.9 to 7.6. The intrinsic surface protonation‐dissociation constants, capacitance density, and phosphate packing area parameters required by the model were adopted from model calculations on reference hydrous oxide minerals. The intrinsic phosphate surface complexation constants were calculated through the application of a nonlinear least squares fitting program to the soil o‐phosphate adsorption data. Two of these intrinsic constants were found to be independent of pH over the range investigated, as required by the model. However, the intrinsic constant for the formation of the neutral o‐phosphate surface species exhibited a statistically significant dependence on pH. The Constant Capacitance model was best able to describe o‐phosphate adsorption by noncalcareous soils, including pH effects, if a soil‐specific set of intrinsic phosphate surface complexation constants was employed.
Soil Gases and Temperatures: A Beef Cattle Feedlot Compared to Alfalfa
Authors: Norstadt Fred A. , Porter Lynn K. 
Published: July 2010

AbstractDry wells or caissons were used in an alfalfa field and at two locations in a feedlot pen to insert instrumentation and sampling devices to characterize the soil profiles. Soil gas compositions and temperatures studied for a 9‐yr period were strikingly dissimilar among the three sampling sites, yet each location had certain consistent properties unique to it. Two distinct areal‐wise soil‐zones had developed in the feedlot pen—one anaerobic and one aerobic. Only the anaerobic, feedbunk site produced methane (CH4). High soil carbon dioxide (CO2) and low oxygen (O2) contents were found there and at the pen center. Dinitrogen (N2) content at the feedbunk site was consistently less than in air which was attributed to a positive CO2 and CH4 pressure from biological sources. The main effects of location and year interacted with either depth or season for the common gases O2, N2, and CO2 at the three caisson sites. The main effects of depth, season, and year on O2 and CO2 were separated at the feedbunk site by excluding the other locations from data analysis. A first order interaction of season by year for N2 and CH4 showed the dependence of those gases on seasonal temperature change modified by years. A significant influence of the caissons on nearby soil temperature gradients was not detected. There were significant positive correlations between soil gas compositions and temperatures for CO2 at all locations and for CH4 at the feedbunk site. Soil N2 content was negatively correlated with soil temperature at both the feedbunk and center sites. These and other complementary results indicate that anaerobic soil conditions beneath a continuously‐maintained, intact, moist manure pack would minimize possible nitrate nitrogen (NO‐3‐N) formation and contamination of soil and groundwater.
A Simplified Soil and Plant Phosphorus Model: II. Prediction of Labile, Organic, and Sorbed Phosphorus
Authors: Sharpley A. N. , Jones C. A. , Gray Carl , Cole C. V. 
Published: July 2010

AbstractSurface samples and soil chemical, physical and taxonomic data for 78 soils from the continental U.S. and Puerto Rico were obtained from the U.S. Soil Conservation Service National Soil Survey Lab. Phosphorus was extracted with the following: NH4F + HCl (Bray 1 P), NaHCO3 (Olsen P), HCl + H2SO4 (North Carolina P), and anion exchange resin (labile P). Organic P and an index of fertilizer P sorption were also measured. Soils were divided into three groups based on soil taxonomy and weathering. Regression analysis was used to obtain equations to predict labile P, organic P, and a P sorption index from soil chemical and physical properties. Labile P was related to extractable P; organic P to total N and pH; and P sorption to clay, CaCO3, labile P, and base saturation. These parameters accounted for up to 84% of labile P variation, 64% of organic P variation, and up to 78% of P sorption variation. Although the equations are empirical, independent variables chosen in the stepwide regression were consistent with P mineralization and sorption relationships previously reported. These relationships were tested using independent data sets. They can be used to generate inputs for the soil P component of the Erosion‐Productivity Impact Calculator crop management model from soil test P and data available in U.S. Soil Conservation Service/State Agricultural Experiment Station Soil Survey Investigation Reports.
Salinity, Sodium, and Potassium in an Irrigated Soil Treated with Bovine Manure
Authors: Pratt P. F. 
Published: July 2010

AbstractResults of a 4‐yr field experiment with liquid feedlot and solid dairy manures and two irrigation rates on a Hanford soil (Typic Xerorthents) are reported. Objectives were to measure the effects of manures on yields of barley and sudangrass forages, the accumulation of salts in the root zone, and the leaching of salts to groundwater. The leaching fraction (LF) calculated from chloride (Cl‐) balances ranged from 0.21 to 0.37. Salinity in the root zone, as measured by the electrical conductivity of the saturation extract (ECe), decreased with increase in LF and was related to the rate and type of manure. Salinity appeared to have no negative effects on yields at manure rates up to 79 Mg ha−1 yr−1. The solid manure at 158 Mg ha−1 yr−1 reduced yields of sudangrass and the ECe for this treatment was in the range of values reported to reduce yields. Manures did not increase the sodium adsorption ratio (SAR). The calculated SAR agreed well with measured SAR values. The potassium adsorption ratio (PAR) increased with increase in rate of manure, but the measured PAR was consistently less than the calculated PAR. There was no effect of irrigation on potassium (K) concentration in the saturation extract or on measured PAR. The data indicated that the soil profile still had considerable capacity to fix K in nonexchangeable forms. The amount of sodium (Na) leached from the root zone exceeded the Na input in water and in manures. The ratio of leached Na to input Na was correlated with LF. The long‐term hazard of the use of manures on well leached irrigated lands appears to be more from K than from Na accumulation.
A Proposed Land Suitability Classification for Potato: I. Methodology
Authors: Manrique L. A. , Uehara G. 
Published: July 2010

AbstractThe principle of matching the biological requirements of a crop to the characteristics of the land was used as a basis for developing a land suitability classification for potato (Solanum tuberosum L.). Land characteristics needed to assess land suitability for potato production were obtained from soil surveys based on Soil Taxonomy. Soil Taxonomy provides readily available information to characterize a few important land qualities for potato production. To predict responses to soil and crop management, land suitability assessments for three levels of input, zero, low, and high, were developed for potato. Because Soil Taxonomy is used as a basis to assess land suitability, the proposed classification system is independent of national boundaries, and can be used to obtain estimates of capabilites of land wherever a soil survey based on Soil Taxonomy is available.
Loess‐Derived Soils, Mississippi Valley Region: II. Soil‐Climate System
Authors: Ruhe Robert V. 
Published: July 2010

AbstractIn Typic Hapludalfs formed in Peoria loess along the Mississippi River Valley from Mississippi to Minnesota, the base status distinctly and abruptly differs at 37° to 38°N latitude. The Memphis soils to the south are more intensively and deeply leached of bases than Alford and Fayette soils to the north. This change coincides with an abrupt historic climatic difference in precipitation (normal and effective). Paleoclimatic reconstruction shows that the climatic boundary could have persisted throughout the Holocene and its changing environments. The constancy of climatic difference through time can account for the soil differences at the critical latitude.
Crop Residue Removal Effects on Corn Yield and Fertility of a Norfolk Sandy Loam
Authors: Karlen D. L. , Hunt P. G. , Campbell R. B. 
Published: July 2010

AbstractTo meet future demands, alternative energy sources will be needed because long‐term energy problems have not been solved. Crop residue may provide a readily available on‐farm bioenergy source, but effects of removing residue on soil fertility, water conservation, and crop production need further investigation. A 4‐yr field experiment was conducted on a Norfolk sandy loam (Typic Paleudults) to determine the effects of removing crop residues on soil pH, extractable nutrient concentrations, and yield of corn (Zea mays L.). Four stover management treatments evaluated between 1979 and 1982 included conventional tillage with stover incorporated, and conservation tillage with 0, 66, or 90% of the stover removed. Treatments were split and evaluated with and without supplemental irrigation. Extractable nutrient concentrations were evaluated by comparing values obtained from an initial soil sampling with those of samples collected each fall thereafter. Ear leaf analyses were used to monitor treatment effects on plant nutrient status. Annual corn stover yields of 3 to 7 Mg ha−1 provided 5 to 11 × 107 kJ ha−1 of potential bioenergy without reducing winter surface cover below 80%. Harvesting corn residues increased annual N, P, and K removal by 26 to 57, 6 to 14, and 49 to 124 kg ha−1, respectively. Soil extractable and plant nutrient concentrations indicated fertilization rates were adequate to compensate for nutrients removed with crop residues. Annual soil analyses showed that surface‐applied lime and fertilizer were rapidly leached through low exchange capacity surface horizons, but accumulated in subsoil horizons even when conservation tillage practices were utilized. Irrigation, tillage, and residue management treatments resulted in few significant differences indicating that in this physiographic region, some crop residues could be utilized for bioenergy production. However, plant nutrients contained in those residues would have to be replaced by increased fertilization.