bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Nitrogen Fertilization of Dryland Wheat on Grain Selenium Concentration
Authors: Soltanpour P. N. , Olsen S. R. , Goos R. J. 
Published: July 2010

AbstractThis study was undertaken to (i) determine the effect of nitrogen (N) fertilization on selenium (Se) content of wheat grain (‘Scout 66’) grown under the dryland fallow system of eastern Colorado and (ii) determine the relationship between grain Se and ammonium bicarbonate‐DTPA soil test levels of Se.Nitrogen fertilization did not affect grain Se where yield was increased significantly in only one out of 10 locations. The ammonium bicarbonate‐DTPA‐extractable level of soil Se was a good indicator of grain Se if 0‐ to 90‐cm soil samples were used (r2 = 0.82). Surface (0 to 30 cm) soil Se levels were weakly related to Se concentration of the grain (r2 = 0.13).
A Modified Line Source Sprinkler Technique for Continuous‐Variable Leaching Studies
Authors: Stark J. C. , Jarrell W. M. , Letey J. 
Published: July 2010

AbstractAn irrigation system designed to produce a continuous range of leaching fractions is described. The leaching variable is produced by supplementing standard sprinkler irrigation with line source irrigation. The advantages of this modified line source technique include (i) the capability of applying a continuous leaching variable to plots receiving uniform applications of sprinkler‐applied fertilizers or pesticides, (ii) the ability to adjust the slope of the water application gradient to produce the desired range of leaching fractions, and (iii) the option of a back‐up irrigation system when wind speed is too great for line source irrigation.
Calibration and Field Testing of a Two‐probe Gamma Gauge
Authors: Rawitz E. , Etkin H. , Hazan A. 
Published: July 2010

AbstractA series of laboratory and field calibration tests was carried out with a commercial double‐probe gamma gauge in an attempt to resolve difficulties encountered in routine field use of the equipment. The laboratory tests showed that transmitted count rate is affected by the extent of the medium surrounding the beam path, indicating that linearity between log of count rate and sample density is not sufficient proof of monochromatic radiation. The equipment was also found to be sufficiently sensitive to require the use of separate attenuation coefficients for soil solids and for water. A universal calibration equation for wet density can therefore not be used with this equipment. Due to the above two phenomena, the calibration stand supplied with the instrument does not yield a calibration curve adequate for accurate work in the field range of soil moisture. A valid calibration therefore requires measurements of moisture and density in a large soil volume over a range of conditions. In view of the technical difficulties in meeting these conditions in the laboratory, empirical field determination of a multipoint calibration curve appears to be the best choice. Once such a curve has been developed, simple two‐point calibration checks of unknown soils could be performed in the laboratory, provided the assumptions of linearity between log of count rate and medium density, and of the effective universality of the attenuation coefficient of soil may be taken as valid. When properly calibrated, the equipment tested is sensitive and reliable for the determination of soil bulk density in the field.
Ion Exchange and Diffusive Mass Transfer During Miscible Displacement Through an Aggregated Oxisol
Authors: Nkedi‐Kizza P. , Rao P. S. C. , Jessup R. E. , Davidson J. M. 
Published: July 2010

AbstractEffluent breakthrough curves (BTCs) for four tracers (3H2O, 14CH3OH, 36Cl, and 45Ca) were measured over a wide range of porewater velocities (3 to 164 cm/hour) using water‐saturated columns of Ione soil, an aggregated Oxisol. Increasing asymmetry of the measured BTCs for all tracers with increasing pore‐water velocity was attributed to decreasing residence time for solute transfer by diffusion between inter‐ and intra‐aggregate regions. The measured BTCs for 36Cl and 45Ca illustrated the role played by the pH‐dependent soil surface charge in determining the retention and transport of ionic species.Measured BTCs were compared with those calculated using a simulation model where (i) convective‐dispersive solute flow was limited to the inter‐aggregate regions, (ii) solute transfer into and out of equivalent spherical aggregates was described by Fick's second law of diffusion, and (iii) isotopic exchange was considered to be an instantaneous reversible process and was described with a linear exchange isotherm. For the slightly sorbed solutes (3H2O and 14CH3OH), all model parameters were independently estimated. Owing to the strong pH‐dependence of isotopic exchange and the inability to exactly duplicate in batch experiments the chemical environment (pH and ionic strength) of the soil columns, exchange coefficients (KD) for 36Cl and 45Ca were estimated by curve‐fitting the model to BTCs measured at the low pore‐water velocity (3 cm/hour). These KD values and all other independently estimated parameters were then used to simulate 36Cl and 45Ca BTCs for the high pore‐water velocity (120 cm/hour). Good agreement was found between measured and calculated BTCs for all tracers. These data and simulations demonstrated the coupling between physical processes (convective‐dispersive flow, diffusive mass transfer) and chemical processes (ion exchange, pH‐dependent charge) in determining the shapes and positions of BTCs obtained from water‐saturated aggregated soils with a variable surface charge.
Soil Pore Structural Stability and Irrigation Water Quality: III. Evaluation of Soil Stability and Crop Yield in Relation to Salinity and Sodicity
Authors: Cass A. , Sumner M. E. 
Published: July 2010

AbstractA method is proposed for quantitative evaluation of the relationship between irrigation water quality and soil structural stability under a specified set of climatic conditions. Quantitative criteria for pore structural stability are provided by a family of threshold concentration curves determined empirically for each soil. After estimating the variation in composition and concentration of soil water as a function of rainfall, evapotranspiration, and soil drainage, intersection of the sodium stability curve with the irrigation water‐soil solution rectangle provides the necessary quantitative index. A similar approach for evaluating crop response to salinity is presented. The method provides quantitative evaluation of irrigation water quality in relation to soil structural stability and crop salinity tolerance.
Transport of Rhizobium and Pseudomonas through Soil
Authors: Madsen Eugene L. , Alexander Martin 
Published: July 2010

AbstractA study was made of the vertical movement of Rhizobium japonicum and Pseudomonas putida added to the surface 2.4 cm of nonsterile soil. Recovery of low numbers of these bacteria was possible because the strains were resistant to combinations of inhibitors that prevented growth of most soil microorganisms on agar media. Viable cells of the two bacteria were not transported below 2.7 cm in moist soil in the absence of some transporting agent or in the presence of developing roots of soybeans (Glycine max (L.) Merr.) or beans (Phaseolus vulgaris L.). Percolating water and a burrowing earthworm (Lumbricus rubellus) enhanced the vertical transport of P. putida but had a smaller effect on R. japonicum. Dispersal of both bacteria was more extensive in the presence of percolating water together with L. rubellus or developing roots. Pseudomonas putida was transported farther and in greater numbers than R. japonicum. However, <1 and 4% of the recovered viable cells of R. japonicum and P. putida, respectively, were present below 2.7 cm.
Agronomic Effectiveness of Pyrophosphate as an Additive to Monocalcium Phosphate and Diammonium Phosphate in Calcareous Soils
Authors: Amer Fathi , Khalil M. A. , Diab G. S. 
Published: July 2010

AbstractRecovery of phosphorus (P) from monocalcium phosphate (MCP) and from diammonium phosphate (DAP), in the presence and the absence of sodium pyrophosphate (NaPP), was determined in the greenhouse on two calcareous soils which had been cropped successively with wheat (Triticum aestivum L.), corn (Zea mays L.), and clover (Trifolium alexandrinum L.). Addition of NaPP to MCP at a pyro‐P/ortho‐P ratio of 1:49 or 5:45 markedly increased wheat grain yield on the desert soil (39% CaCO3), and responses to 50 ppm P with additive were not statistically different from those to 100 ppm P without additive. Sodium pyrophosphate tended to increase P recovery from MCP by the wheat and by the following corn on the alluvial soil (4.1% CaCO3), and only by the wheat on the desert soil. By the end of the cropping experiments total P recovery was considerably lower on the desert than on the alluvial soil, especially with DAP. The highest recoveries were obtained with the additive treatments. At the rate of 50 ppm P, total recovery from MCP increased with 1 ppm additive from 48.1 to 55.4% on the desert soil and from 57.5 to 71.6% on the alluvial soil. With DAP, the beneficial effect of the additive was not significant at the 0.05 level. In soil columns, addition of NaPP enhanced mobility of MCP to a greater extent than that of DAP. The results suggest that DAP may not be recommended for soils high in CaCO3 content.
Characteristics of the Colo Soil Series as Mapped in the North Central Region
Authors: Collins M. E. , Fenton T. E. 
Published: July 2010

AbstractThe Colo soil series (fine‐silty, mixed, mesic Cumulic Haplaquoll) was sampled and studied in areas mapped as Colo in the North Central Region (NCR). Within this broad geographic area, there are variations in climate, vegetation, parent material, relief, and time—the five soil‐forming factors. This soil is mapped on floodplains of streams and in drainageways of various size. Forty‐seven soil profiles from five states were described and sampled to determine selected physical, chemical, and mineralogical properties and the ranges of these properties in this series.The principal objectives of this investigation were to (i) study one soil series and characterize the series as mapped, (ii) compare Colo soil properties with associated upland soils, and (iii) develop a model to better understand the genesis of soils derived from alluvial sediments in the NCR.Depth distribution of selected chemical and physical properties in some Colo profiles indicated some degree of horizon differentiation. Clay, total phosphorus (TP), inorganic phosphorus (IP), and available phosphorus (AVP) depth distributions in many profiles had a zone of eluviation and illuviation, indicating redistribution of these constituents within the profile. One possible interpretation of the redistribution is that the soils are on landforms that have been stable for some period of time. Total carbon (TC) content usually decreased regularly with increasing depth. Clay mineralogical analyses indicated a dominance of interstratified clay minerals. Smectite, kaolinite‐chlorite, and illite are minor clay minerals in these soils as interpreted from relative peak heights. For most profiles, clay mineralogy was similar with increasing depth.Statistical model equations involving several physical, chemical, and mineralogical parameters, as dependent or independent variables, were developed.
Genesis of Maryland Soils Formed from Serpentinite
Authors: Rabenhorst M. C. , Foss J. E. , Fanning D. S. 
Published: July 2010

AbstractFour pedons developed over serpentinite were characterized. Eluvial and illuvial processes have caused formation of weak‐to‐moderately‐expressed argillic horizons. Magnesium‐rich parent materials are responsible for the dominance of Mg on the exchange complex, except in surface horizons where H+ prevailed. Also due to the Mgrich parent materials, extractable Ca/Mg ratios decreased with depth ranging from 0.8 to 2.45 at the surface to 0.03 to 0.17 above the bedrock. The pH values increased with depth from 4.9 to 5.6 at the surface to 6.6 to 6.8 above the bedrock. Total nickel and chromium concentrations were between 180 and 18,900 ppm and 400 to 5,850 ppm, respectively.Weathering of serpentine minerals tends toward the formation of smectite, which, with vermiculite, dominates the fine (clay) fractions. These are often interstratified with hydroxyinterlayered minerals. Serpentine minerals, while absent from the <0.2‐µm fraction, occurred with chlorite and vermiculite in the 2‐ to 5‐ and 0.2‐ to 2‐µm fractions. The presence of the silicon‐rich minerals, mica, feldspars, and quartz in the upper portions of the pedons indicates that some eolian materials have been added to the serpentinite residuum. This is substantiated by elemental analyses of the silt fractions.
Determining and Evaluating Nutrient Losses Following Whole‐tree Harvesting of Aspen
Authors: Silkworth D. R. , Grigal D. F. 
Published: July 2010

AbstractNutrient loss following whole‐tree harvesting of aspen (Populus tremuloides Michx.) was assessed on coarse‐loamy Typic Fragiochrepts in northeastern Minnesota. We used a methodology that could be applied to other systems to roughly estimate the impact of harvesting on nutrient capital. Ceramic cups collected soil solution through the frost‐free season at 130 cm on sites harvested 1, 2, and 5 years before and on undisturbed sites (total = 24). Nutrients in vegetation, soil, and forest floor were also determined. An evapotranspiration model predicted the flux of water moving through the soil. Soil solution concentrations peaked in midsummer. Nitrogen concentrations in solution were below detection limits, and P concentrations were not related to harvesting. Potassium in soil solution decreased, and Ca and Mg increased on harvested sites compared to undisturbed sites. After adjusting for leaching flux, only Ca showed a statistically significant loss associated with harvest in the first 5 years after the harvest (60 kg/ha). Over a 60‐year rotation, precipitation and normal weathering will replace N, P, and K lost by product removal and deep leaching, will replace about one‐half the Mg, but will not replace Ca. Because of their initial abundance in the soil, Ca and Mg will probably not become nutritionally deficient, but their loss may lead to accelerated soil acidification and associated secondary effects.
The Influence of Anthropogenic Sulfur Inputs upon Soil Properties in the Copper Basin Region of Tennessee
Authors: Wolt J. D. , Lietzke D. A. 
Published: July 2010

AbstractAnthropogenic sulfur (S) released from historical copper‐sulfide ore smelting in the Copper Basin of Tennessee provides an example of acid‐sulfate weathering from which the long‐term impact of acid‐sulfate precipitation upon soils of the Southern Appalachians may be inferred. Three similar soils (clayey and fine‐loamy, oxidic, mesic Typic Hapludults) were described and sampled downwind from smelter operations in the Copper Basin along a gradient of diminishing S input. The soil at the site of high S input, in the heart of the Copper Basin, contained twofold greater total S in the B2t horizon in comparison to the soil at a site of low S input approximately 11 km downwind. Decreased soil pH and increased exchangeable acidity were also associated with high levels of S input. Comparison of the clay fractions isolated from soils sampled from sites of varied S input indicated decreased gibbsite and total potassium (K) contents and increased kaolinite contents for soils subjected to higher levels of S input. The trends in total K, kaolinite, and gibbsite distributions are consistent with a mechanism whereby gibbsite was destroyed and K‐mica weathered to kaolinite in the past environment of the Copper Basin. The formation of an Al‐hydroxy‐sulfate compound as a consequence of the weathering processes may account for the greater levels of S retention by soils subjected to higher levels of S input.
Soil Solution Nutrient Concentrations Sampled with Tension and Zero‐Tension Lysimeters: Report of Discrepancies
Authors: Haines B. L. , Waide J. B. , Todd R. L. 
Published: July 2010

AbstractLysimeters were used to sample soil solutions in an ecosystem‐level study of nutrient cycling in a southern Appalachian deciduous forest watershed. Four lysimeters were installed at each of 16 randomly designated locations. At each location, first at the litter‐soil interface and again 30 cm beneath the litter‐soil interface, one tension and one zero‐tension lysimeter were installed side by side. Samples for 13 time intervals over a 15‐month period were analyzed for water volume, H+, NH+4, K+, Na2+, Ca2+, Mg2+, NO‐3, Cl‐, SO2‐4, H2PO4‐, and dissolved silica. The sums of cations, the sums of anions, and the anion deficit (unmeasured anions) were calculated for each collection. Estimates of soil solution composition and water flow differed according to lysimeter type. At the litter‐soil interface the zero‐tension lysimeters collected 7 times more water flow which had significantly higher concentrations of H+, Ca2+, and SO2‐ and significantly lower concentrations of Na+, K+, and Cl‐ than collections from tension lysimeters. At a soil depth of 30 cm, zero‐tension lysimeters collected 2.1 times less water which had significantly higher concentrations of NH+4, K+, NO‐3, Cl‐, SO2‐4, sums of cations, and sums of anions but significantly less silica than collections from tension lysimeters. A testable hypothesis is advanced to account for these observed discrepancies.
Effect of Pyrophosphate on Phosphate Sorption and Ammonia Volatilization by Calcareous Soils Treated with Ammonium Phosphates
Authors: El‐Zahaby E. M. , Chien S. H. , Savant N. K. , Vlek P. L. G. , Mokwunye A. U. 
Published: July 2010

AbstractTechniques are needed to simultaneously reduce phosphorus (P) precipitation and ammonia (NH3) volatilization from MAP and DAP (monoammonium‐ and diammonium phosphate). The purpose of this study was to investigate the inhibitory effect of sodium pyrophosphate (NaPP) on P precipitation and NH3 volatilization in a pure calcium carbonate (CaCO3) system and in two calcareous soils from Egypt.In the CaCO3 system, additions of NaPP‐P equivalent to 4 and 8% of MAP‐P and DAP‐P, respectively, reduced the amounts of P sorption and NH3 volatilization. Solution ammoniacal‐N was higher with PP than without it for both MAP and DAP. Pyrophosphate acts as a nucleation and/or crystal growth inhibitor for dicalcium phosphate dihydrate (DCPD), thereby maintaining higher solution P concentrations. Because NaPP inhibits the formation of DCPD, the pH of the solution was lowered by its addition, which, in turn, reduced NH3 volatilization. Pyrophosphate did not affect NH3 volatilization from NH4Cl in the CaCO3 system since no insoluble reaction products were formed. The solution pH values were about the same for NH4Cl with or without NaPP in the CaCO3 system. The reaction of DAP with CaCO3 did not directly affect NH3 volatilization but indirectly increased solution pH which, in turn, controlled NH3 volatilization.In the soil system the inhibitory effect of NaPP was relatively more effective in reducing P sorption and NH3 volatilization from MAP than from DAP, and its effect lasted longer in the soil with less CaCO3 content than in the other soil. The effect of NaPP increased when the rate of PP‐P was increased from 2 to 4% of MAP‐P, but no further reduction in NH3 volatilization was noted between 4 and 8% on either soil. The inhibitory effect of PP on P sorption from MAP, however, did increase with an increase in PP‐P from 4 to 8%. Sodium pyrophosphate reduced the P sorption and NH3 volatilization from DAP more efficiently if applied in solution form or applied to the dried soil surface followed by the addition of water than if NaPP was applied to the premoistened soil surface. This is probably related to the dissolved PP concentration in the soil solution. In summary the results obtained with the soil system are in agreement with the results obtained with the pure CaCO3 system.
The Effect of Soil Drainage on Phosphorus Status and Availability to Corn in Long‐term Manure‐amended Soils
Authors: Kuo S. , Baker A. S. 
Published: July 2010

AbstractThe effect of soil drainage on phosphorus (P) transformation and availability in soils was examined in a field that received annual manure applications for more than 20 years. The soil in the field ranged from well‐drained Briscot loam (Typic Fluvaquents) to poorly drained Schalcar muck (Terric Medisprists) and was planted with corn (Zea mays L.) in 1979. Ten weeks after planting, soil and plant tissue samples were collected for P analysis.Manure applications increased the P content of the soils considerably. Most of the added P from manure remained in the surface soils (0 to 30 cm), though some downward movement of P did occur. Poor soil drainage increased the accumulation of P in the organic matter (NaOCl‐extractable) and in the amorphous Fe‐Al oxide (oxalate‐extractable) soil fractions, but reduced the amount of P in the acid (0.5N H2SO4)‐soluble soil fraction. Drainage affected the P desorption and availability to corn plants as well. The poorly drained Schalcar muck soil, for instance, had less P extractable by dilute HCl‐H2SO4 or NaHCO3 solution than the well‐drained Briscot loam soil, despite the higher total P content of the muck soil. The rate of P desorption by NaHCO3 can be described by two zero‐order rate equations after an initial rapid desorption. The rate constant of desorption for the poorly drained soil (0.058 µg ml−1 min−1) was lower than for the well‐drained soil (0.082 µg ml−1 min−1).The marked influence of soil drainage on P availability and transformation in the manure‐amended soils observed in this study suggests that the selection of appropriate soils for manure disposal is necessary for better recycling of this nutrient by plants.
Oxygen Consumption and Denitrification Kinetics in Soil
Authors: Cho C. M. 
Published: July 2010

AbstractOxygen consumption and CO2, N2O, and N2 production from a slurry of a slightly acidic soil incubated in a closed container with several different concentrations of NO‐3 were investigated using a mass spectrometer. Under unshaken conditions, the rates of O2 consumption and CO2 production changed with time. Nitrous oxide and N2 gases were produced even though there was ample O2 in the atmosphere above the stagnant water. Under these conditions the rates of O2 consumption and N2O, N2, and CO2 production were controlled by the kind and rate of supply of electron acceptors to the sites of denitrification. When well shaken, the rate of O2 consumption was constant. The CO2 production rate had two distinctive values. The rate of CO2 production when O2 was still in the system was greater than the value obtained after O2 in the system was all depleted. Nitrous oxide started to appear only when O2 was completely consumed. Under the shaken conditions, the measured rates of O2 consumption, CO2, and N2O production were independent of NO‐3 concentration; however, the average life and the maximum concentration of N2O were directly related to initial NO‐3 concentration.It is useful to define a parameter, denitrification intensity (DNI), which is proportional to the potential maximum rate of electron production for a soil with constant microbial activity under fixed temperature. Determination of the DNI must be made when the rate of electron acceptor (NO‐3 or NO‐2) supply is not limiting the reaction. Under these conditions, the inhibition of conversion of N2O to N2 results in the rate of N2O‐N production which is greater than the rate of production of the sum of N2O‐N and N2‐N without inhibition. If the rate of supply of electron acceptors (NO‐3 or NO‐2) is smaller than DNI, a parameter, gaseous nitrogen production rate (GNPR), the magnitude of which is unaffected by the inhibition of conversion of N2O to N2, characterizes the denitrification process.