bluuebunny/crossref_metadata_2025_split huggingface dataset:
Isolate Selection and Phosphorus Interaction of Vesicular‐Arbuscular Mycorrhizal Fungi in Biomass Crops
Authors: Hung L. L. , Sylvia D. M. , O'Keefe D. M. 
Published: July 2010

AbstractIndustrial sweet potato [Ipomoea batatas (L.) Lam, cv. White Star] and Napiergrass (Pennisetum americana × P. purpureum hybrid triploid PI 300086) have good potential for biomass energy systems. The objective of this research was to evaluate vesicular‐arbuscular mycorrhizal (vam) fungi for their ability to provide P to these crops across a range of soil P. To select effective vam fungi, cuttings of sweet potato were inoculated with nine isolates of fungi and were grown in soil with no P addition. Plants were evaluated after 3, 7, and 11 wk. To determine the range of soil P where these crops respond to vam fungi, experiments were conducted with sweet potato and Napiergrass, using at least two vam fungi and five P additions ranging from 0 to 198 mg P kg−1 of soil. Plants were evaluated after 4 and 16 wk. Sweet potato response to vam fungi ranged from growth enhancement to growth depression, compared to control plants. Both inter‐ and intraspecific fungal variation was observed. Total biomass production at 11 wk was correlated positively with root colonization at 3 wk, but not at 7 or 11 wk. Mycorrhizal dependency for both biomass plants decreased with P addition; nonetheless, growth was greater for plants inoculated with vam fungi and with up to 23 mg added P kg−1. The apparent ineffectiveness of the indigenous vam fungi, and the responsiveness of these biomass crops to selected vam fungi within a practical range of fertilizer P, may provide an opportunity for inoculation.
Relating High Soil Test Phosphorus Concentrations to Plant Phosphorus Uptake
Authors: Yerokun Olusegun A. , Christenson D. R. 
Published: July 2010

AbstractThe median P soil‐test concentration in Michigan has increased above the point at which a yield response is expected from fertilizer P application. This study was conducted to determine whether several soil‐P extractants reflect plant P uptake under high residual soil P conditions and to estimate the reduction in soil‐test P concentration as a result of crop removal. Initial P concentrations of the surface 0‐ to 15‐cm layer of ten Michigan soils were determined with Bray‐Kurtz P1, Bray‐Kurtz P2, Olsen, and anion‐exchange resin (AER) as extracting solutions. Ten consecutive crops were grown for 5 wk each on each soil. Phosphorus uptake by each crop was calculated from yield and composition. Linear correlation coefficients among the Bray‐Kurtz P1 and P2, Olsen P and AER P methods ranged from 0.79 to 0.99. Linear correlation coefficients between initial test P concentrations and cumulative P uptake were from 0.40 to 0.74. The highest correlation was with the Olsen extractant and the lowest was with Bray‐Kurtz P1 (1:20). A comparison of change in extracted soil‐P content with P uptake showed that the Bray‐Kurtz P1 extractant at a soil/solution ratio of 1:20 and the Bray‐Kurtz P2 extractant most closely estimated the magnitude of P removed by plants. On the cultivated soils, there was a change of 0.13 to 0.31 mg P kg−1 soil in the Bray‐Kurtz P1 soil test for each mg P kg−1 soil removed by plants.
Characteristics of “Coal Bloom” Horizons in Undisturbed Forest Soils in Eastern Kentucky
Authors: Sainju U. M. , Kalisz P. J. 
Published: July 2010

AbstractWeathered coal seams (blooms) commonly occur at depths <150 cm under benches on steep slopes in eastern Kentucky. Since blooms are within the reach of tree roots and are C‐rich, they may affect nutrient availability and tree growth. This study was conducted to characterize the properties of blooms, and to examine growth and nutrient uptake by trees grown on blooms in the greenhouse. Samples were collected from eight profiles and properties of blooms were compared with those of overlying A horizons. Blooms occurred at a median depth of 68 cm and were generally loamy; coarse‐fraction concentrations were <100 g/kg, and bulk densities ranged from 0.56 to 1.25 Mg/m3. Compared with overlying A horizons, blooms had higher C (median values, 216 vs. 37 g/kg), total N (4.0 vs. 1.9 g/kg), and C/N ratios (48 vs. 21), and lower Ca (0.2 vs. 0.8 cmolc/kg), P (1 × 10−3 vs. 7 × 10−3 g/kg), and mineralizable N (8 × 10−3 vs. 50 × 10−3 g/kg). Available water capacity of disturbed samples (range 0.13–0.32 m3/m3) and pH (3.4–5.0) were similar for blooms and A horizons. Root densities were much greater in A horizons, but densities in blooms were greater than predicted for horizons formed at the same depth in colluvium. Yields and nutrient concentrations of yellow poplar (Liriodendron tulipifera L.) grown in the greenhouse on blooms were low, probably due to a shortage of available N. Blooms are of low fertility and apparently do not affect forest composition under natural conditions.
Water Vapor Transport through a Flail‐Chopped Corn Residue
Authors: Tanner C. B. , Shen Y. 
Published: July 2010

AbstractCrop residue at the soil surface is known to decrease evaporation, and measurements have shown that wind increases evaporative loss through residues; however, to our knowledge, measurements of water vapor flux through residues have not defined their vapor conductance. The objective of this study was to measure the water vapor transport through crop residues in a wind tunnel and under natural wind and to parameterize the vapor conductance in a way useful for modeling the energy balance of conservation‐tillage systems. The vapor conductance of flail‐chopped corn (Zea mays L.) residue laid over large vapor sources (0.15 by 1.2 m) at different vapor‐pressure gradients was measured in still air and under winds. In still air, the vapor conductance of 10 samples of residue (areal density = 0.4 kg m−2; average thickness = 11 mm) averaged 2.2 mm s−1 at 20 °C and was not significantly different than the conductance of a similar thickness of air. Error in the measurement (CV = 13%) was sufficient that porosity and tortuosity effects on conductance could not be determined. Buoyancy‐driven convection in the flail‐chopped residue was negligible under much greater buoyancy instabilities than are likely to occur in the field. The vapor conductance (h) of nine samples of residue measured in a wind tunnel increased linearly with wind speed (V) measured at 1 m above the residue: h = (2.2 mm s−1) (1 + 0.89V), with a standard error of estimate (Syx) of 1.82 mm s−1. The regression coefficients of vapor conductance vs. wind found in the wind tunnel and under natural winds did not differ at P = 0.25. Based on our experience, measurements of conductance of other residues would be done much more easily in a suitable wind tunnel than in the field, and with the same results.
Water‐Drop Kinetic Energy Effect on Infiltration in Sodium‐Calcium‐Magnesium Soils
Authors: Keren R. 
Published: July 2010

AbstractThe effect of the complementary adsorbed ion (Ca vs. Mg) in the presence of Na on seal formation and water infiltration in two soils (Calcic Haploxeralf and Typic Rhodoxeralf) at several kinetic energies of water drops was studied using rain simulators. The infiltration rate (IR) of the soils was lower for the Na‐Mg soils than for the Na‐Ca soils at the studied kinetic energy range of the water drops (3.2–22.9 kJ m−3). The higher the kinetic energy, the steeper the drop in IR. The steady‐state IR and the cumulative water depth required to reach steady‐state IR were both decreased with increasing kinetic energy of the water drops. Adsorbed Mg on montmorillonitic soils had a specific effect on IR whether or not the soil contained CaCO3. Aggregates with adsorbed Na and Ca ions were more stable than those with adsorbed Na and Mg ions when they were exposed to water drops having a kinetic energy in the range of 8.0 to 12.5 kJ m−3. The specific effect of Mg on IR was explained by the presence of Mg ions on the external surfaces of the clay tactoids and the larger hydration shell of the Mg ion compared to Ca.
Phosphate Adsorption and Desorption by Goethites Differing in Crystal Morphology
Authors: Torrent J. , Barrón V. , Schwertmann U. 
Published: July 2010

AbstractGoethite is an important component influencing phosphate adsorption in many soils and sediments. Little is known, however, about the relationships between crystalline properties and phosphate adsorption and desorption by this mineral. In this study we investigated the phosphate adsorption and desorption properties of 31 synthetic goethites differing widely in specific surface area, crystal morphology, and AIOOH mole fraction. The amount of phosphate adsorbed per unit surface area at pH 6 and an equilibrium concentration of 6 mg P L−1 was similar for all goethites (x̄ = 2.51, SD = 0.17 µmol P m−2), suggesting that the common crystal faces have similar P‐sorbing capacities. This condition is compatible with the existence of only (110) faces; in fact, according to transmission electron microscope (tem) observations, both natural and synthetic goethites seem to be bound by only (110) faces. The amount of phosphate nonextractable by 0.1 M KOH, and the amount not extracted by dissolving one layer of one‐unit‐cell thickness with an acid (HCl‐H2SO4) treatment, are related to crystal morphology: samples consisting of thin, multidomainic laths retain more P than those having thick, monodomainic crystals. It is hypothesized that the presence of V‐shaped interdomainic grooves and/or the slit‐shaped macropores of multidomainic laths accounts for stronger P bonding and/or low accessibility of the hydroxyl or hydronium ions.
Crust Formation Effects on Soil Erosion Processes
Authors: Moore Daniel C. , Singer Michael J. 
Published: July 2010

AbstractSoil seals and crusts reduce soil infiltration rates and increase soil strength. How they affect the erosion process is not entirely clear. Effects of soil crusts at different stages of formation on soil erosion processes were analyzed and presented within the context of a model that divides crust formation into pre‐runoff, increasing runoff, and steady‐state runoff stages. Soil detachment trends accompanying crusting were characterized for Capay silty clay loam (fine, montmorillonitic, thermic, Typic Chromoxerert), Jacinto loam (fine‐loamy, mixed, thermic Mollic Haploxeralf), and Gridley coarse sandy loam (Typic Argixeroll). Soils crusts were formed on 61 by 61 cm2 plots inclined at 9% slopes using simulated rainfall applied at 42.5 mm h−1 as 3.2‐mm‐diam. drops falling 2.5 m. Photographs of crust surfaces were taken at selected times to provide additional morphological evidence to support conclusions drawn from erosion data. Soil splash and runoff materials were collected at intervals, and selected samples were analyzed for particle size distribution. In all three soils, erosion rates reached maximums during the period of increasing runoff, then decreased and tended toward equilibrium levels during the final, steady‐state runoff period. This suggests that crust formation decreases soil erodibility under these steady erosivity conditions. Splash erosion rates peaked during the period of increasing runoff, while wash erosion rates displayed a gradual increase over the periods of increasing and steady‐state runoff. These trends are related to the decreasing size and degree of aggregation of surface material available for detachement, and the buildup of a layer of overland flow that appeared to enhance splash detachment while retarding splash transport. Between‐soil differences in the rate of soil crust development, as inferred from progression through the three runoff stages, suggest an interaction between initial soil texture and soil aggregate stability.
Sampling Device to Extract Inclined, Undisturbed Soil Cores
Authors: Vepraskas M. J. , Hoover M. T. , Beeson J. L. , Carpenter M. S. , Richards J. B. 
Published: July 2010

AbstractA sampling device was constructed to extract undisturbed cores of soil or similar material at angles between 0 and 90° from the vertical. The sampler consisted of a hydraulic cylinder suspended from an arm of a backhoe. Undisturbed cores (76‐mm in ht. by 76‐mm in diam.) were collected in metal rings, which were inserted into a Uhland‐type sample holder. The hydraulic cylinder pushed the sample holder into the soil material and also extracted it. Twenty‐five undisturbed, inclined cores could be collected with this device in 3 hr by three people. Saturated hydraulic conductivity was measured on 120 saprolite cores using a double‐ring permeameter to assess boundary flow. No boundary flow was detected between the sample ring and core edge. Examination of the cores' internal fabric, as seen in thin sections made from each of the 120 cores, confirmed that the cores were virtually undisturbed.
Quantification of Postsettlement Deposition in a Northwestern Illinois Sediment Basin
Authors: Kreznor W. R. , Olson K. R. , Jones R. L. , Johnson D. L. 
Published: July 2010

AbstractThe purpose of this study was to quantify the postsettlement deposition in a 24 900‐m2 (2.49‐ha) sediment basin with a single outlet in a 105 400‐m2 (10.54‐ha) watershed and estimate the sediment delivery to a first‐order stream in northwestern Illinois. Methods included direct measurements of the eroded sediment deposited in the sediment basin. Buried A horizons (dated using fly ash as a time marker) identify the presettlement (≈1854) surface, which was overlain by as much as 116 cm of sediment. Volume of the sediment within the basin was calculated at 11 394 m3 with a weight of 16 480 Mg. The modern soils of the sediment basin were characterized, classified, and the spatial variability of the sedimentation process was examined. Based on representative measurements of postsettlement sediment delivery obtained from research of drainage basins having similar size or soil characteristics, it was inferred that 20 975 Mg of sediment was delivered to the stream with a total of 37 455 Mg of soil being removed from the watershed hillslopes as a result of accelerated soil erosion. The measured rate of postsettlement sediment accumulation has been approximately 0.34 cm yr−1. Based on the tightly packed deposits, redeposition probably occurred as overland flow during storm events, rather than as overland flow occurring after a rainfall or as rain‐splash transport. However, machinery traffic and cultivation could have contributed to the high soil bulk density. Intensive cultivation, biotic activity, and freeze‐thaw are probably responsible for destroying any evidence of stratification.
Release of Nonexchangeable Potassium from a Highly Weathered, Forested Quartzipsamment
Authors: Comerford N. B. , Harris W. G. , Lucas D. 
Published: July 2010

AbstractLong‐term K supply is often considered a function of the amount of K‐bearing minerals present. Hydroxy‐interlayered vermiculite (HIV) is a ubiquitous secondary mineral of the southeastern lower Coastal Plain and is now known to be associated with nonexchangeable K in these soils. Oxalate has also been shown to exist in millimolar quantities in these soil solutions. The objective of this study was to test the effect oxalate has on the potential solubility of K in a forested Quartzipsamment containing appreciable HIV in the < 50‐µm fraction, but no other detectable K‐bearing minerals. Samples were prepared, chemically extracted, and extracting solutions analyzed for K. We found that: (i) K can be released from clay and silt fractions by oxalate concentrations ranging from 1 to 150 mM and pH 3 to 6; (ii) sequential extractions with oxalate removed the most K during the first extraction with the silt being depleted of readily released K after three to four extractions but with the clay releasing K continuously over seven extractions; (iii) low pH was as effective in the release of K as oxalate at higher pH; (iv) after a 210‐ to 240‐d incubation of the extracted samples, re‐extraction resulted in high levels of K being released, even from the silt fraction that had been previously depleted; (v) electron microprobe analysis and K x‐ray images suggested that K contents were higher in the center of the phyllosilicate grains than near the edges.
Acetonitrile and Acrylonitrile Sorption on Montmorillonite from Binary and Ternary Aqueous Solutions
Authors: Zhang Z. Z. , Sparks D. L. , Scrivner N. C. 
Published: July 2010

AbstractThe main objective of this study was to gain mechanistic information on clay‐organic interactions in aqueous environments containing multiple organics. Three different measurements were made to achieve this objective. The sorption of acetonitrile and acrylonitrile on K, Na, Ca, and Mg montmorillonite from binary and ternary aqueous solutions were determined using a 14C isotope tracer method. The infrared spectra of acrylonitrile in solution and adsorbed on montmorillonite were recorded on a Fourier‐transform infrared (FTIR) spectrometer and the c‐axis spacings of montmorillonites in the acrylonitrile solutions were determined by x‐ray diffraction. It was found that the sorption of acetonitrile and acrylonitrile from ternary solutions on K montmorillonite was competitive across the entire concentration range. The sorption was slightly competitive at lower concentrations on Na, Ca, and Mg montmorillonite, but enhanced at higher concentrations. The competitive sorption on K montmorillonite was probably associated with the decrease in the interfacial volume, since the layers of K montmorillonite were collapsed at higher concentrations, while the enhanced sorption on Na, Ca, and Mg montmorillonite appeared to be caused by an increase in the partition coefficient as more organic molecules entered the interfacial phase. These results led to the conclusion that the sorption of acetonitrile and acrylonitrile on montmorillonite was not due to specific bonding between the organic molecules and the clay surfaces, but rather to a partition between the interfacial phase and the bulk solution phase.
Microwave Radiation and Incubation Effects on Resin‐Extractable Nutrients: I. Nitrate, Ammonium, and Sulfur
Authors: Yang Jae E. , Skogley Earl O. , Schaff Bernard E. 
Published: July 2010

AbstractThe phytoavailability soil test (PST) is a resin‐extraction methodology being developed for use on fresh soil samples. Mineralization of N and S during shipment of samples to a soil‐testing laboratory is of concern with this soil‐test approach. The objective of this research was to investigate microwave‐radiation (MWR) treatment of soil samples to arrest microbial conversions of nutrients during incubation of fresh samples. Fresh samples from three Ap horizons of Montana soils (Haploborolls) with different fertility histories were subjected to MWR for 0 to 4 min, and then incubated at 20 °C for 0 to 12 d. Subsamples were also dried before being subjected to the same treatments. Nutrients were extracted with mixed‐bed ion‐exchange resin extractors placed in saturated pastes of each sample and by standard soil tests on dried soil samples. Results for NO3‐N indicate that MWR prevented nitrification, but extractable NH4‐N and S varied in a manner suggesting release of interlayer NH4 and thermal decomposition of organic components. Compared with standard soil tests, PST was similar in sensitivity to changes in NO3‐N and S and more sensitive to changes in NH4‐N. These soils had up to three times more NH4‐N than NO3‐N in either the fresh or dried condition. Based on these results, MWR is not recommended for arresting microbial activity prior to extraction for soil‐test purposes, either by standard or PST methods. Changes in the two forms of plant‐available mineral N occurring during shipment or increases in total mineral N or S may need to be dealt with through other means of microbial arrest, or through calibration adjustments.
Soil Sampling under No‐Till Banded Phosphorus
Authors: Kitchen N. R. , Westfall D. G. , Havlin J. L. 
Published: July 2010

AbstractUncertainty exists about the best sampling procedures for no‐till soils containing residual P‐fertilizer bands. This study was conducted to determine the distribution of residual P‐fertilizer bands and to define soil sampling procedures that minimize variability, while approximating the “true” P‐soil‐test value. A no‐till, banded‐P‐fertilization field study was conducted during 1986 and 1987 on three central Great Plains soils: Keith clay loam (a fine‐silty, mixed, mesic Aridic Argiustoll), Woodsen silt loam (a fine, montmorillonitic, thermic Abrubtic Argiaquoll), and Harney silt loam (a fine, montmorillonitic, mesic Typic Argiustoll). Soils were sampled laterally away from the band 1 to 2 yr after fertilization, and P was determined with NaHCO3 and acid‐fluoride extractions. Bands were accurately described by the exponential decay model (mostly r2 values of 0.98 or better). The derived exponential equations were used in computer evaluation of soil‐sampling procedures. When the location of P bands are known, sampling to include one in‐the‐band soil sample for every 20 between‐the‐band samples for 76‐cm band spacing, and for every eight between‐the‐band samples for 30‐cm band spacing, will result in a P soil test equal to the “true” P‐soil‐test mean. When the location of P bands is unknown and <20 subsamples are taken, paired sampling consisting of a first completely random sample and a second sample 50% of the band‐spacing distance from the first sample, perpendicular to the band direction, will reduce variability over completely random sampling. The greatest deviation from the “true” P soil test occurs when inadequate sampling includes rather than excludes the band, and will thus under‐estimate P‐fertilizer needs.
Agronomic Evaluation of Two Unacidulated and Partially Acidulated Phosphate Rocks Indigenous to Niger
Authors: Chien S. H. , Henao J. , Christianson C. B. , Bationo A. , Mokwunye A. U. 
Published: July 2010

AbstractA field study was conducted on a sandy soil in Niger to evaluate the agronomic effectiveness of various P fertilizers for millet production during 1985 to 1987. The P fertilizers tested were two finely ground phosphate rocks (PR) indigenous to Niger (Tahoua and Parc W rocks), PR partially acidulated with H2SO4 at 50% acidulation level (PAPR), single superphosphate (SSP), and triple superphosphate (TSP). In 1985, application rates were 0, 6.5, 13.0, and 19.5 kg P ha−1 for each of the P fertilizers. In 1986, half of the plots received the same rates of P as in 1985 and half of the plots received no additional P. In 1987, P additions were repeated only in half of the plots that received P during 1986. A significant (P = 0.05) millet response to P was observed in all the trials. The major findings of this study were: (i) finely ground Tahoua PR was more effective than Parc W PR because of its higher reactivity and was 82 to 91% as effective as SSP for millet production in both the initial and two subsequent seasons; (ii) partial acidulation of Parc W PR can significantly increase its agronomic effectiveness in the first year, but not in terms of residual effect; (iii) partial acidulation was not a desirable technology for increasing the effectiveness of Tahoua PR, because its high Fe2O3 plus Al2O3 content resulted in a product containing relatively low amounts of water‐soluble P; and (iv) over a period of 3 yr, one initial application of a large dose of P fertilizer was found to be more effective than three small annual applications in terms of total grain production.