bluuebunny/crossref_metadata_2025_split huggingface dataset:
Statistical Relationships among Selected Properties of Northern Cameroon Vertisols and Associated Alfisols
Authors: Yerima B. P. K. , Wilding L. P. , Hallmark C. T. , Calhoun F. G. 
Published: July 2010

AbstractSix Usterts and one Ustalf developed from lacustrine sediments and Precambrian schists in northern Cameroon were characterized for physical, chemical, and mineralogical properties. Correlative statistical relationships were established among physical and chemical properties including surface area (SAT), shrink‐swell (COLE), cation exchange capacity (CEC), percent total clay (PCL), percent coarse clay (PCCL), percent fine clay (PFCL), water retention at 33 kPa (WAT), organic carbon (OC), calcium carbonate equivalent (CCE), pH, and exchangeable sodium percent (ESP). In general, upland soils, developed from Precambrian schists and sandstones, yielded lower correlation coefficients among these properties than lowland soils developed from Quaternary fluvial deposits. For the lowland soils, COLE was highly correlated with SAT, PCL, and WAT; simple coefficients of determination (r2) were 0.91, 0.80, and 0.74, respectively. Similar correlations were obtained for COLE for upland soils, but neither CCE for these soils, nor ESP for either upland or lowland soils were significantly correlated with COLE. The CEC of soils studied was highly correlated with SAT and PCL; r2 values ranged from 0.59 to 0.91. The SAT of Usterts in lowlands was very highly correlated with PCL, PFCL, PCCL, CEC, and COLE; these independent variables generally accounted for greater than 90% of the variance in SAT. For Usterts and Ustalfs of uplands, the SAT was not so closely correlated with these parameters, especially PFCL and PCCL, which varied in amount and clay mineralogy with depth. Multiple linear regressions did not generally improve predictive abilities for COLE, CEC, and SAT over simple linear relationships. Regression relationships developed constitute useful predictive indices for estimating engineering and agronomic properties from existing physical and chemical data and soil survey reports of northern Cameroon.
Mapping Depth to Bedrock on a Glaciated Landscape with Ground‐Penetrating Radar
Authors: Collins M. E. , Doolittle J. A. , Rourke R. V. 
Published: July 2010

AbstractIn many upland areas on glaciated landscapes, it is difficult to examine soil profiles and determine the depth to bedrock. Glacial rock fragments and irregular or weathered bedrock surfaces limit the effectiveness of auger techniques. While general trends can be inferred from the landscape, depth to bedrock or thickness of till cannot be accurately predicted from landscape position alone. Therefore, ground‐penetrating radar (GPR) was used to map the depth to bedrock for two study sites in Maine. Data were used to (i) determine the variability of the depth to bedrock in similar delineated areas of a map unit, (ii) compare the accuracy of GPR with auger methods, and (iii) evaluate the performance of GPR on a glaciated landscape in Maine. Results were confirmed by studying a trench excavated to bedrock. These results indicated that GPR techniques were more reliable and effective than conventional auger techniques for determining the depth to bedrock, and thus for determining the composition of map units that are based on soil‐depth criteria. Additionally, the screw auger was shown to be an unreliable tool for determining soil depths in moderately coarse‐textured tills having large amounts of coarse fragments.
Impact of Crop Production on the Physical Status of a Typic Albaqualf
Authors: Scott H. D. , Wood L. S. 
Published: July 2010

AbstractExtensive tillage during long periods of time affects soil productivity by altering soil properties. Quantitative measurements were made to determine the combined effects of duration of tillage and production of soybean [Glycine max. (L.)] and rice (Oryza sativa) on selected physical and chemical properties of a Crowley silt loam (fine, montmorillonitic, thermic Typic Albaqualf). Four adjacent fields were sampled which included a virgin prairie and three fields in cultivation for 1, 12, and 30 yr. Undisturbed soil cores were taken at 0.05‐m depth intervals to 0.15 m and analyzed for soil water retention at 10, 30, 50, 80, 100, 500, and 1500 kPa, bulk density and saturated hydraulic conductivity. Organic matter content, pH, and particle size were determined on disturbed samples. Compared with the cultivated soils, the prairie had higher organic matter contents. The 12‐yr and 30‐yr fields in cultivation had higher pH values and bulk densities but lower water retained at a given pressure than the prairie and 1‐yr field in cultivation. No differences were found with respect to particle‐size distribution. For a given soil property, values of CV were affected by time in production but not by depth. The CV was low in the prairie, increased in the 1‐ and 12‐yr fields and in the 30‐yr field was similar to values found in the prairie. The greatest changes in organic matter and bulk density occurred in the initial 12 yr of cultivation. The temporal variability of organic matter contents in the surface 0 to 0.05‐m interval was mathematically modeled with both constant and variable rate equations.
Wheat Residue Loss from Fields under No‐till Management
Authors: Stott D. E. , Stroo H. F. , Elliott L. F. , Papendick R. I. , Unger P. W. 
Published: July 2010

AbstractTo successfully implement no‐till crop management systems for winter wheat (Triticum aestivum L.), knowledge is needed on how rapidly large residue fragments are lost. At five sites in Washington, Texas, and Indiana, losses of surface‐managed winter wheat residues were measured over time. Sites were sampled periodically by using grab samples to determine weight loss per unit area. Thirty weeks after harvest, residue weight losses ranged from 35 to 42% and, after an additional 5 wk, losses ranged from 38 to 55%. Snow cover provided insulation for residues, allowing decomposition to continue during winter when sufficient moisture was present. On chemical fallow plots, there was a 50 to 80% loss after a year. On plots seeded with a no‐till spring crop, residue losses ranged from 81 to 88% by harvest time. Contributions of various sources of residue mass loss are discussed. Effect of residue loading rate was also determined; the highest residue loading rate exhibited the smallest losses. After a year, there was 75, 72, and 50% residue weight loss from the 1680, 3360, and 6720 kg ha−1 plots, respectively. At three sites, changes in the surface area covered by the decomposing residues was measured. Initial coverage from harvest ranged from 93 to 99%. Coverage declined to between 85 and 95% after winter.
Tillage and Fertilizer Effects on Water Infiltration
Authors: Zuzel J. F. , Pikul J. L. , Rasmussen P. E. 
Published: July 2010

AbstractTillage techniques have been linked to the formation of tillage pans, which cause reduced infiltration capacity and increased runoff and erosion. Reduced infiltration is especially detrimental on steeply sloping agricultural lands, which are common in many areas of the Pacific Northwest and elsewhere. Infiltration rates in three long‐term tillage treatments with two fertilizer levels were measured using a rainfall simulator. Tillage treatments were plow, disk, and sweep, and have been continuous since 1940. Nitrogen fertilizer has been applied at 45 or 180 kg/ha since 1962. Final infiltration rates for the plow, disk, and sweep treatments averaged 17, 14, and 16 mm/h, respectively. The final rate for the high‐N treatment averaged 22 mm/h vs. 9 mm/h for the low‐N treatment. Results also indicate that surface sealing by raindrop impact and soil frost are probably more important than the tillage pan in controlling the infiltration capacity. Analysis of the infiltration‐rate curves strongly indicates that, if surface sealing is prevented by a complete residue cover, the type of tillage does not have a significant effect on infiltration and is not a major factor in reducing the infiltration capacity of this soil. Conversely, fertility level is an important determinant of infiltration capacity, apparently because of the additional biomass produced by the crop.
Soil Source, Seed Source, and Organic‐Matter Content Effects on Douglas‐Fir Seedling Growth
Authors: Page‐Dumroese D. S. , Graham R. T. , Harvey A. E. , Loewenstein H. 
Published: July 2010

AbstractDouglas‐fir [Pseudotsuga menziesii var. glauca (Beissn.) Franco] seedling success on harvested areas in northern Idaho is often limited on harsh sites because of moisture and nutrient stress. This study was conducted to determine the importance of soil source, seed source, and organic matter on seedling growth and nutrition. Soil and seed were taken from both high‐ and low‐elevation sites at the Priest River Experimental Forest, Priest River, ID. In a greenhouse, seed was sown in both home‐source soil (taken from local seed‐collection zone) and nonsource soil (taken from opposite seed‐collection zone) mixes. Soil mixes included 100% organic, 50% organic/50% mineral, or 100% mineral soil. Seedlings were measured for height, bud length, root collar diameter, dry root and shoot weight, total N, total P, K, and number of ectomycorrhizal roots tips g−1 of dry root. Both soil and seed sources had similar nutrient and growth characteristics for each of the three soil mixes. One hundred percent organic soils, after only one growing season, produced seedlings that were significantly taller and had greater bud length, root collar diameter, and biomass than those growing in either mineral soil or the organic/mineral mix. Total N and P uptake was greater in the organic soil than in the mineral soil or the mix, but K uptake was greater in pure mineral soil. Low‐elevation seed‐source trees were always taller than their high‐elevation counterparts, an apparent result of adaptation to longer growing seasons. The best ectomy‐corrhizal colonization took place in the mineral soil mix. Ectomy‐corrhizae were most prolific on seedlings grown in nonsource soil when compared with those grown in home‐source soil. Regeneration success in the Inland Northwest will be substantially improved by maintaining the integrity of organic horizons on harvested areas and by adhering closely to seed‐transfer‐zone guidelines.
Ammonia Volatilization from Urea as Influenced by Soil Temperature, Soil Water Content, and Nitrification and Hydrolysis Inhibitors
Authors: Clay D. E. , Malzer G. L. , Anderson J. L. 
Published: July 2010

AbstractResidue cover influences temperature and water gradients in the soil profile. Changes in the physical environment of the soil influence NH3 volatilization from urea‐containing fertilizers. Field and laboratory experiments were conducted to investigate the influence of residue‐cover‐induced changes in soil water and temperature on NH3 volatilization as impacted by urea treatment with a nitrification and urease inhibitor. Fertilizer treatments were urea, urea plus dicyandiamide (DCD), urea plus N‐(n‐butyl)thiophosphoric triamide (NBPT), and urea plus NBPT and DCD. Following fertilizer application, the soil was either left bare or covered with corn (Zea mays L.) residue. Every 3 h over a 4‐d period, water potential, soil temperature, CO2 production, and NH3 volatilization were measured. The influence of fertilizer treatments on soil pH was determined in a laboratory incubation experiment conducted over 8 d under controlled environmental conditions. Treatments were similar to the field experiment, with NH3 volatilization, pH, and CO2 production measured daily. The NH3‐volatilization rate in the field was highest 2 d after urea application at a time that corresponded with daily maximum soil temperature and decreasing soil water content. Residue cover reduced NH3 volatilization. Volatilization of NH3 as a result of urea application was not increased when urea was treated with DCD. Ammonia volatilization as a result of urea treatment with NBPT was reduced by 100 times over untreated urea. During an incubation experiment, soil pH increased from 6.5 to 7.2 in the urea‐NBPT, and from 6.5 to 9.0 in the urea and urea‐DCD treatments. Associated with the pH increase in the urea‐NBPT treatment was a reduction in CO2 production when compared with the untreated soil.
High‐Gradient Magnetic Concentration of Chlorite and Hydroxy‐Interlayered Minerals in Soil Clays
Authors: Weed S. B. , Bowen L. H. 
Published: July 2010

AbstractIdentification and characterization of chlorite and hydroxy‐interlayered layer‐silicate minerals (HIM) common to many soils of the Atlantic Coastal Plain would benefit if the minerals could be concentrated and isolated by a suitable technique that would not alter them chemically or mineralogically. High‐gradient magnetic separation (HGMS) meets these requirements and was used in this study as a pretreatment in the analysis of soil clays. Deferrated coarse clay (2–0.2 µm) of soil material from several Ultisols on the Coastal Plain of North Carolina was subjected to HGMS using magnetic fields ranging from 0.04 to 0.89 T. Resulting fractions were analyzed by x‐ray diffraction, differential thermal analysis, Mössbauer spectroscopy, and total chemical analysis. Iron‐substituted Ti oxides, including rutile, ilmenite, anatase, and pseudorutile were found in the fractions separated at low magnetic field; chlorite was found at higher field strengths; HIM was separated at medium to high fields; kaolin and quartz plus HIM were found in the tailings. Mössbauer spectroscopy showed the chlorite to contain Fe2+ indicating that it is inherited primary chlorite. The chlorite is trioctahedral and constitutes <10 g kg−1 of the coarse clay; the HIM is dioctahedral and appears to make up >650 g kg−1 of the coarse clay. Structural formula of the HIM calculated from total chemical analysis of Casaturated clay and assuming a negative charge of 49 per unit cell layer is (Ca0.07K0.26Na0.15)(Si7.38Al0.62) (Al2.87Fe0.63Mg0.50)O20(OH)4Al1.86(OH)5(H2O)0.58, suggesting a phengitic muscovite or celadonite precursor. The cation exchange capacity (CEC) based on Ca content in the total analysis is about 15 cmolc kg−1 of HIM. The HGMS was effective in simplifying the mineralogical composition of materials studied, based on Fe content of the components.
In Situ Measurements of Soil Physical Properties by Acoustical Techniques
Authors: Sabatier J. M. , Hess H. , Arnott W. P. , Attenborough K. , Römkens M. J. M. , Grissinger E. H. 
Published: July 2010

AbstractKnowledge of porosity, air permeability, pore structure, and surface layering of soils is desirable in agricultural research. The conventional techniques are invasive, typically requiring sample extraction. When monitoring seasonal changes, the conventional methods disrupt considerable proportions of the test plot surface. The sample area used in conventional measurements may be too small to represent the variations in the test plot. Here, the feasibility of acoustical techniques for monitoring surface air porosity (total porosity minus volumetric water content), air permeability, and pore structure and the variation of these properties to depths of several centimeters below the surface is demonstrated. Test soil plots prepared using three soil materials, masonry sand, a Grenada silt loam (fine‐silty, mixed, thermic Glossic Fragiudalf) and a Catalpa silty clay (fine, montmorillonitic, thermic Fluvaquentic Hapludoll), were considered. Variation in water content and compaction of each soil material were considered. Both acoustic reflection and transmission measurements were made in the audio‐frequency range. The soils are modeled as air‐filled, rigid‐framed porous media. The acoustic‐reflection measurements involve analysis of propagation data from a small loudspeaker and two vertically separated microphones. The acoustic‐transmission measurement requires a specially designed probe microphone. Analysis of the acoustic‐reflection data yields qualitative indications of the relative air permeability of the soils. The transmission measurement yields information about the changes in air permeability with depth. Quantitative information on surface porosity, air permeability, tortuosity, and layering is presented by fitting theoretical predictions based on the soil model to the measured sound reflection and transmission data. The acoustically determined air porosity for the soils considered is within 10% of the values determined by gravimetric techniques.
X‐ray Photoelectron Spectroscopy as a Tool to Differentiate Silicon‐Bonding State in Amorphous Iron Oxides
Authors: Vempati R. K. , Loeppert R. H. , Dufner D. C. , Cocke D. L. 
Published: July 2010

AbstractAn x‐ray photoelectron spectroscopy (XPS) study was conducted to: (i) compare the Si (2p) and O (1s) peaks of selected Si‐containing minerals, and (ii) evaluate the application of XPS in identifying probable Si‐bonding environments in Si‐containing ferrihydrites. For silica gel, the Si (2p) and O (1s) XPS peaks occurred at 104.0 and 534.2 eV, respectively; with biotite, these peaks occurred at 102.8 and 532.4 eV. The difference in the Si (2p) binding energies between silica gel and biotite was attributed to differences in the Si‐bonding environment and the number of ‐Si‐O‐Si‐ linkages at corners of the SiO4 tetrahedron, and the charge deficit in the tetrahedral layer of biotite. The Si (2p) XPS peak for silicate adsorbed on ferrihydrite occurred at 100.9 eV, which indicated the probable presence of ligand‐bound silicate or small units of polymerized silica at the ferrihydrite surface. For ferrihydrite samples treated with an excess of Si (≥75 g kg−1), peaks attributable to a separate Si‐rich phase were identified on decomposition of the Si (2p) and O (1s) XPS peaks. In the case of ferrihydrite coprecipitated with silicate at Si/Fe molar ratios ≥0.10, the Si (2p) peak occurred at approximately 102.8 eV, which is a position similar to that observed for layer silicates, indicating the possible presence of Si, i.e., the presence of ‐Fe‐O‐Sl‐ bonds, within the ferrihydrite structure.
Mineralization of Amino Acids and Evidence of Direct Assimilation of Organic Nitrogen
Authors: Barak Phillip , Molina J. A. E. , Hadas Aviva , Clapp C. E. 
Published: July 2010

AbstractRival hypotheses, the mineralization‐immobilization‐turnover (MIT) hypothesis and the direct hypothesis, contend that deamination of soluble, low‐molecular‐weight nitrogenous compounds in soil is mediated by either extracellular or intracellular enzymes, respectively. To test these hypotheses, two amino acids, glycine (C/N = 1.7) and leucine (C/N = 5.2), were added to an acid Hubbard loamy sand (sandy, mixed Udorthentic Haploboroll) and incubated for 7 d. Net mineralization of both C and N were S‐shaped functions of time, indicating that simple first‐order substrate‐dependent kinetics were not applicable. The net mineralization of C and N were strongly correlated with each other and reflect the C/N ratio of the substrate and the C/N ratio and microbial efficiency of the microbial biomass. Labeled 15N data, when analyzed using kinetic models reflecting either the direct or MIT hypotheses, reject the MIT hypothesis (α = 0.01) and show evidence of direct incorporation of amino acids into the microbial biomass.
Soil Property Relationships with SPOT Satellite Digital Data in East Central Illinois
Authors: Agbu Patrick A. , Fehrenbacher Donald J. , Jansen Ivan J. 
Published: July 2010

AbstractThe second‐generation remote sensing satellites with improved spatial and spectral resolution offer additional possibilities for conducting soil surveys. This study was undertaken to determine the relationships that exist among high‐resolution satellite digital data and soil properties useful in map‐unit delineation and classification. A second objective was to develop models (linear equations) based on soil properties to predict satellite spectral response. Site, morphological, physical, and chemical soil properties were determined to a depth of 1.2 m for 442 observation sites in two rectangular grids, at two contrasting areas of 3108 ha each. Multiple‐regression analyses between SPOT spectral data and soil properties showed that many surface and some subsurface soil properties were significantly correlated to spectral data. Landscape position and percent slope were not important as site characteristics that predict satellite spectral variables. Color of dominant mottles and depth to loess did not significantly affect satellite data. Measured soil properties were tested in terms of their usefulness in predicting SPOT spectral response. The results showed that most surface soil properties and some subsurface properties pertinent to soil classification and map‐unit separation can be used to predict satellite data and vice versa. Brightness index proved to be a more useful spectral parameter if surface soil properties are to be extracted from spectral data, but ratioing of the original data resulted in more association of spectral data with subsurface soil properties.
Characterization of Tillage and Traffic Effects on Unconfined Infiltration Measurements
Authors: Ankeny Mark D. , Kaspar T. C. , Horton R. 
Published: July 2010

AbstractTillage and wheel‐traffic compaction alter pore structure and hydraulic properties of agricultural soils. These alterations will affect root growth and movement of water and solutes. This study was conducted to develop new methods needed to characterize the effects of wheel traffic and tillage on pore structure as measured by water flow through macropores. Unconfined (three‐dimensional) saturated and unsaturated infiltration measurements (0‐, 30‐, 60‐, and 150‐mm water tension) at the soil surface were taken sequentially at field sites to determine the steady‐state rate of water flow through different pore‐size classes on a Tama silty clay loam (fine‐silty, mixed, mesic Typic Argiudoll). A tension infiltrometer was used to obtain the unsaturated infiltration rates. Sites were selected on trafficked and untrafficked interrow positions in two tillage systems (chisel plow and no‐till). Steady‐state infiltration rates from 2 to 300 µm s−1 were measured. Increasing the tension of applied water resulted in decreasing infiltration rates for both tillages and traffic treatments because, as tensions increased, larger pores emptied. Wheel traffic reduced infiltration rates in both tillages, but caused a greater decrease in infiltration rates in the chisel‐plow system than in no‐till. Increasing tension caused proportionately smaller decreases in infiltration rates for wheel‐trafficked positions. This suggests that larger macropores were transporting a greater proportion of the total water flow in untrafficked soil than in trafficked soil and reinforces the concept that larger, as opposed to smaller, pores are more easily destroyed by wheel traffic. Unconfined infiltration measurements were shown to be useful in quantifying the effects of tillage and compaction on soil macropores.