bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hydraulic Properties of Some Soils with Paralithic Contacts
Authors: Paetzold R. F. , Mausbach M. J. 
Published: July 2010

AbstractSeveral soils containing paralithic contacts over sedimentary materials were studied. Hydraulic and related soil physical properties were determined in an effort to explain root restriction associated with paralithic contacts. These properties were evaluated for their usefulness as criteria in confirming the presence and location of paralithic contacts. Bulk density ranged from 1.21 to 1.78 Mg m−3 in C horizons and from 1.17 to 2.05 in Cr horizons. No statistical difference was found between C and Cr horizon bulk densities. Paired determinations showed no statistical difference in bulk density between the horizon immediately above and the horizon immediately below a paralithic contact. Similar results were obtained for total porosity and air‐filled porosity at 33 kPa water content except that there was a statistical difference in air‐filled porosity at 33‐kPa water content between C and Cr horizons in fine‐textured soils. Although Cr horizons retained more water at both 33 and 1500 kPa than C horizons, the water retention difference was the same for both C and Cr horizons. Hydraulic conductivity values were similar for all horizons within a particular soil. No abrupt or unusual change, in any soil property measured, was observed at a paralithic contact. High bulk density and poor water supplying ability were eliminated as aids useful in identifying and locating paralithic contacts in the materials studied.
An Evaluation of Potassium Hydroxide Extractable Aluminum in Andepts (Andisols)
Authors: Kimble J. M. , Holzhey C. S. , Holmgren G. G. S. 
Published: July 2010

AbstractPotassium hydroxide‐extractable Al is proposed as the basis of a field or laboratory criterion for the classification of Andepts (Andisols). Twelve pedons from volcanic‐derived parent material were studied, and in all of the pedons that met the existing criteria for an exchange complex dominated by amorphous material, KOH‐extractable Al was > 20g kg−1 (2%). Since this extraction is quick and easy and can be run in the field, it will allow soil scientists to distinguish andic materials from others in the field.
Field Identification of Spodic Horizons with Potassium Hydroxide Extractable Aluminum and Humic Acid Color
Authors: Holmgren G. G. S. , Yeck R. D. 
Published: July 2010

AbstractFifty‐nine previously classified soils were analyzed for humic acid color and KOH aluminum. These variables were used to develop alternate criteria for the spodic horizon by comparing data with the existing classifications. The resulting criteria are as follows: Humic acid color greater than or equal to 10 L platinum color units per gram or, maximum B horizon KOH‐extractable Al > 7 g kg−1 (0.7%), with a ratio of maximum Al in the B horizon to minimum Al in the E horizon of 2 or more. This latter requirement is necessary to distinguish Spododols from Andepts if the KOH aluminum criterion is used. Soils with discrepant classifications by laboratory data, field morphology, and by these alternate criteria were examined to bring out the reasons for the differences. A second set of soils was then examined in terms of the proposed criteria. Of this second set, 88% were classified by the proposed criteria in agreement with either the laboratory or the field estimate of the classification. The principal disagreements in both sets of soils could be explained as a consequence of the questionable exclusion from Spodosols of soils with low pyrophosphate (Fe + Al)/dithionite (Fe + Al) ratios and by the effect of high or low clay contents on the pyrophosphate (Fe + Al)/clay ratio requirement. In some cases, the classification more closely corresponds to the field morphology than does classification by the existing laboratory criteria. A principal advantage is that the procedures can be performed under field conditions.
Effects of Soybeans on Soil Properties Related to Soil Erodibility
Authors: Bathke G. R. , Blake G. R. 
Published: July 2010

AbstractResearch was conducted from 1980 to 1982 to examine the relationship between soybean (Glycine max L.) cropping and enhanced soil erodibility. Soil samples from the 1‐to10‐cm layer were taken from contiguous fields, cropped to soybeans and corn (Zea mays L.) the previous season, across Southern Minnesota in the spring of 1980 (1980 field survey) and the spring of 1982 (1982 field survey) and analyzed for their aggregation tendencies. In the 1980 field survey, aggregate size, stability, and carbon content were lower following soybeans than corn. The 1982 field survey indicated a reduced cloddiness in soybean fields when compared with corn fields by using a rapid field sieving test. Percent by weight of clods > 19 mm was less, and percent by weight of clods < 10 mm was greater following soybeans than corn. Field plots were established to study the soil‐protecting effect which has been attributed to a soybean canopy. A soybean canopy was not effective in maintaining aggregate size or stability during the growing season over that of a bare soil. Leaving soybean residue on the soil surface during winter resulted in larger, more stable aggregates than plots with no cover or residues. A second set of field plots was designed to investigate the effects of a soybean or corn crop and combinations of surface residue conditions on soil properties. Aggregates were of equal size but significantly less stable after soybeans compared with corn when sampled in the fall. In the spring the aggregates were less stable at one location and of equal stability at two locations, but were smaller in size due to soybean cropping at all locations. Replacing soybean with corn residue during winter generally had no consistent significant effect on soil aggregation. This leads to the conclusion that there is an effect of the growing crops themselves, or of their root remains, or both on soil aggregates, but not attributable to above‐ground residue differences between crops.
Tillage Effects on Surface Soil Physical Conditions and Sorghum Emergence
Authors: Unger Paul W. 
Published: July 2010

AbstractTillage and soil crusts, among other factors, influence seedling emergence. Crust strength (CS) is related to crust water content (WC), which is influenced by tillage. Tillage also influences surface soil physical conditions that may be related to CS. This study tested the hypothesis that different tillage methods result in different CS at similar times after rainfall or irrigation and determined which tillage‐mediated soil factors were responsible for CS differences of Pullman silty clay loam (fine, mixed, thermic Torrertic Paleustolls). Tillage treatments during fallow from winter wheat (Triticum aestivum L.) harvest to grain sorghum [Sorghum bicolor (L.) Moench] planting were moldboard (MT), disk (DT), rotary (RT), sweep (ST) and no‐tillage (NT). Initial tillage usually caused the greatest differences in surface conditions. Subsequent tillage and weathering eliminated most differences by sorghum planting time. Moldboard tillage, which covered most residues, usually had the greatest effect and NT, which maintained surface residues, usually had the least effect on surface conditions. Conditions evaluated were organic matter content, dry aggregate size, modulus of rupture of briquettes, crushing resistance of briquette fragments, random roughness, surface residues, and crust strength and water content. Sprinkler irrigations after sorghum planting did not result in crusts that impeded seedling emergence, but more intense rain may have caused problems. Because surface conditions generally improved with time after initial tillage, results of this study suggest that major tillage, where used, should be performed well before planting to minimize plant establishment problems. Adverse surface conditions can be minimized by using a conservation tillage system, such as NT.
Effects of Clearfelling and Site Preparation on Nitrogen Mineralization in a Southern Pine Stand
Authors: Burger J. A. , Pritchett W. L. 
Published: July 2010

AbstractA clearcut forest site (45‐year‐old natural stand of Pinus elliottii Engelm. and Pinus palustris Mill.) was subjected to different intensities of site preparation to determine management impacts on N availability. Using a laboratory aerobic soil incubation technique, N mineralization potentials (N mineralizable over time) (No) were determined to be 25.0, 23.3, and 17.7 µg/g for soils from an uncut control area; a burned and chopped area; and a bladed, disced, and bedded area, respectively. The No of soil from the intensively treated area was significantly lower than the others when measured in the laboratory; however, simulations of field conditions indicated that more N may be mineralized in soils from intensively treated sites due to more favorable soil moisture and temperature conditions. Mineralization rates for these three areas, however, were not significantly different, and C/N ratios (28 and 26 for the chopped and bladed sites, respectively) for the clearcut and prepared areas did not suggest a difference in N availability. Ratios of organic matter/soluble carbon (OM/Ca) increased from 79 to 136 with treatment intensity and suggest that the N associated with the organic matter remaining on the most intensively treated site may be more resistant to decomposition. Nitrogen availability is a function of substrate quality and microenvironmental conditions. Harvesting and site treatment affected both of these. Laboratory determinations of No appear to be a better index of nitrogen availability than C/N, Cs, or total N, but do not adequately account for differences in mineralization due to treatment‐induced changes in the soil environment.
Extraction of Aluminum from Aluminum‐Organic Matter in Relation to Titratable Acidity
Authors: Hargrove W. L. , Thomas G. W. 
Published: July 2010

AbstractThis study was conducted to further characterize aluminum (Al)‐organic matter complexes and their role in soil acidity. The objective was to determine the extractability of Al from organic matter and to relate it to titratable acidity. Two samples of muck were treated with Al3+ in such a way as to achieve a range in Al saturation. The titratable acidity [determined conductimetrically with Ca(OH)2] of selected samples was compared to the Al extracted with 1 M KCl, 0.5 M CuCl2, 2 M HCl, 1 M NH4OOCCH3 (pH 4.8), 0.5 M CaCl2, and 0.33 M LaCl3. Results show that NH4OOCCH3 (pH 4.8) is a very poor extractant of Al associated with organic matter. For unbuffered salts, the effectiveness of the extractant generally decreased as the valence of the replacing cation decreased (i.e. La3+ > Ca2+ > K+). Copper is an exception to this rule as a result of its ionic structure and its tendency to form “inner sphere” complexes with organic matter, displacing a disproportionate fraction of the Al. Lanthanum extracts an amount of Al which seems well related to the titratable acidity and, thus, to the lime requirement. On the other hand, K+ extracts far too little Al, while Cu2+ extracts all of the Al present. The use of LaCl3 to predict lime requirement on field soils (especially where organic matter is increasing such as for no‐tillage, etc.) looks promising but needs widespread evaluation.
Determination of Total Potassium, Sodium, Calcium, and Magnesium in Plant Materials by Ion Chromatography
Authors: Basta N. T. , Tabatabai M. A. 
Published: July 2010

AbstractA simple, accurate, and precise ion chromatographic (IC) method for determination of total K, Na, Ca, and Mg in plant materials was developed. It involves dry ashing approximately 0.1 g of plant material, followed by dissolution of the residue in 5 mM HCl and determination of K, Na, Ca, and Mg in the digest by using a Dionex Model 10 IC. The IC method is based on separation of the cations by a separator column containing low‐capacity, cation‐exchange resin in the H+ form and on converting the various cations to their corresponding hydroxide forms by a suppressor column in the OH‐ form. The eluent used for determination of K and Na was 5 mM HCl, and that used for determination of Ca and Mg was 2.5 mM HCl + 2.5 mM m‐phenylenediamine dihydrochloride. Electrical conductivity is used as the mode of detection. Results showed that the average total K values in 25 plant materials by IC, atomic absorption spectrophotometry (AA), and flame photometry (FP) were 3.08, 3.08, and 3.07%, respectively. The corresponding average total Na values were 0.258, 0.264, and 0.256%. The average total Ca values in the same plant samples by the IC and AA methods were 1.20 and 1.19%, respectively. The corresponding average total Mg values were 0.327 and 0.331%. The IC method developed has the same degree of precision as that of AA or FP method. The IC method has an excellent sensitivity with detection limits of 0.1, 0.05, 0.1, and 0.03 mg L−1 of K, Na, Ca, and Mg, respectively. With the IC method, K and Na can be determined simultaneously in 6 min, or Ca and Mg can be determined in 7 min. A single operator can perform about 40 analyses of K and Na or Ca and Mg in a normal working day.
Phosphate Sorption by Some Alfisols of Greece as Described by Commonly Used Isotherms
Authors: Polyzopoulos N. A. , Keramidas V. Z. , Kiosse Helen 
Published: July 2010

AbstractThe one‐ and two‐surface Langmuir, the Freundlich, and the Temkin isotherms were fitted to P sorption data for 14 representative alfisols of Greece. Each was found to describe P sorption by these soils with comparable success, with the Freundlich and the two‐surface Langmuir isotherms being slightly superior. The Freundlich equation is characterized by simplicity of form, based on more realistic assumptions, and now capable of rigorous derivation. It can therefore be used in preference to the others, since its parameters, as those of the Langmuir equation, allow comparisons among soils.
Electron Spin Resonance Investigation of Copper(II) Complexation by Fulvic Acid Extracted from Sewage Sludge
Authors: Senesi Nicola , Bocian David F. , Sposito Garrison 
Published: July 2010

AbstractElectron spin resonance (ESR) spectra are reported for copper (II) − fulvic acid complexes prepared with fulvic acid (FA) samples extracted from two different anaerobically‐digested sewage sludges. The nominal Cu/FA molar ratios employed were in the range 0.08 to 80. In the original Cu‐FA solutions, quadridentate, nearly square planar complexes with FA donor ligands could be inferred from the ESR spectra only at the smallest Cu/FA molar ratio, whereas at the intermediate ratios mixed Cu‐FA‐H2O complexes became more evident and at the highest ratio free Cu2+ aquo‐ions prevailed. Treatment of the Cu(II)‐FA solutions at any Cu/FA molar ratio with the strongly acidic cation exchange resin Bio‐Rad AG‐MP‐50 eliminated excess Cu(II) aquo‐ions and, therefore, permitted a better differentiation of classes of FA functional groups participating, to different degrees, in the coordination of Cu(II). The ESR spectra suggested the formation of inner‐sphere, polydentate complexes, with the Cu(II) coordinated equatorially by oxygenated and nitrogenated FA ligands. ESR parameters of the resulting Cu(II)‐FA complexes showed the existence of binding sites involving both 4 O and 2 O, 2 N ligand atoms, as well as a minor, more nitrogenated site (1 O, 3 N). No saturation of the Cu(II) complexation capacity was observed, but increasing the Cu content involved less and less reactive functional groups of FA in the coordination, shifting the complexation equilibria towards the formation of weaker complexes. Further information about binding mechanisms was developed through a comparative analysis of ESR data obtained for Cu(II)‐FA complexes both in aqueous solution and in air‐dried state. A significant rearrangement of the Cu‐FA systems was suggested to take place upon air‐drying of the resin‐treated Cu/FA solutions.
Pedoturbation of a Forest Soil by Fire Ants
Authors: Lockaby B. G. , Adams J. C. 
Published: July 2010

AbstractThe influences of the imported fire ant (Solenopsis invicta) on the mixing of forest soils on three sites in north Louisiana were examined. Soil bulk density, pH, percent organic matter, and concentrations of P, K, Ca, and Mg were compared for samples from ant mounds vs. adjacent undisturbed soil at two depths. In surface samples bulk density was lower and organic matter, P, K, Ca, and Mg were higher on the mounds. Soil pH did not change. In subsurface comparisons only organic matter and K differed and were higher in the mound samples. Results are discussed in terms of the depth of ant activity, the quantity of soil excavated, and the organic matter, P, K, Ca, and Mg content of that soil. Questions are raised regarding the role of fire ants in the decomposition of tree stumps.
Single Column Ion Chromatography: I. Analysis of Inorganic Anions in Soils
Authors: Nieto K. Fitzpatrick , Frankenberger W. T. 
Published: July 2010

AbstractA useful analytical method is described for the determination of inorganic mono‐and divalent anions in soils. Single column ion chromatography (SCIC) is a rapid, sensitive, and precise method which can simultaneously detect Cl−, NO−2, NO−3, SO2−3, and SO2−4 in soils in less than 10 min. In addition, Br−, I−, and ClO−4 can be separated within 15 min. The method can be carried out on a commercially available HPLC instrument, using a 500 µL aliquot of soil extract and an eluent stream of 4 mM phthalic acid (pH 4.5). The inorganic anions are separated on a low‐capacity anion exchange column and quantified by conductimetric detection. Results obtained by the SCIC method agree closely with those obtained by other analytical methods: Cl−, AgNO3 titrimetric method (r = 0.987***); NO−2‐N, diazonium coupling reaction (r = 0.993***); NO−3‐N, steam distillation (r = 0.998***); SO2−4‐S, autoanalyzer (r = 0.998***). Using a 500 µL loop, SCIC detection limits, expressed in mg/L of soil extract, were: Cl−, Br−, NO−3‐N, and SO2−4‐S (0.025), ClO−4 and I− (0.5); NO−2‐N and SO2−3‐S (1.0). Several extracting reagents (water, LiCl, KCl, Ca[C2H3O2l2, and CaCl2) were compared to determine the best soil extraction procedure. This method proved to be reproducible as evident by the low CV values ranging from 3.6 to 8.4%. Notable advantages of this technique include: (i) single column simplicity, (ii) application to a wide variety of inorganic anions, (iii) simultaneous determination of ions in soil extracts without interferences by soil constituents, and (iv) inherent sensitivity greater than most methods employed for the determination of inorganic soil anions.
Effect of Phosphorus on the Effectiveness of Strains of Rhizobium japonicum
Authors: Singleton P. W. , AbdelMagid H. M. , Tavares J. W. 
Published: July 2010

AbstractWe examined the relationship between P nutrition of soybean [Glycine max (L.) Merr. cv. ‘Davis’] and N2 fixation by five strains of Rhizobium japonicum ranging from an ineffective (SM‐5) to a highly effective (USDA 110) symbiosis with soybean. Phosphorus at 0, 50, 125, and 400 mg P kg−1 soil (P0, P50, P125, P400) as Ca(H2PO4)2 · H2O was applied to pots containing 2.7 kg of a P‐fixing humoxic tropohumult free of R. japonicum. Treatments consisting of + N and five strains of R. japonicum and the four P treatments were arranged in a complete factorial replicated three times. With 400 mg P kg−1 soil treatments ranked + N > USDA 110 > USDA 31> USDA 123> USDA 33>SM‐5 for shoot dry weight and accumulation of N in the shoot. There were no significant strain effects for shoot dry weight, shoot N or nodule activity at Po. Strain rankings were the same at the intermediate levels of P but differences were smaller. Although nodule number was somewhat enhanced by P, it bore no relationship to strain effectiveness and was not a factor limiting N2 fixation at low P. Nodule dry weight and nitrogenase activities significantly increased with P additions. The concentrations of N and P in the shoot also increased with P additions. The concentrations of shoot P and N were higher in plants provided mineral N at the low and intermediate P levels than in the inoculated plants. The results show that P nutrition is important in interpreting the N2 fixation capability of strains of Rhizobium. Synergism between P and Rhizobium inputs requires that to obtain maximal response to the application of one input necessitates employing the other at maximum levels.
Soil Profiles: Nitrogen Conversion and Salt Motility Altered by Feedlot Manure Management
Authors: Norstadt Fred A. , Duke Harold R. 
Published: July 2010

AbstractTwo manure management plans were successively imposed on soil profile combinations of clay loam, sand, clay loam over sand, and sand over clay loam to study salt movement and nitrogen (N) transformations in a beef cattle feedlot. These soils were placed in replicated lysimeters located in each of two areas of a feedlot stocked at the rate of one animal, weighing 270 to 450 kg, per 15.2 m2. After loading the soils with N, including nitrate nitrogen (NO−3‐N), by means of a manure‐sawdust mulch for 4 yr (first manure management plan), cores were removed for physical and chemical analyses. Then, the mulch was changed to an intact‐manure pack for 2.5 yr (second manure management plan) which was followed by a second coring and soil analyses. Each management plan and profile combination affected salt movement and N transformations differently. The intact‐manure pack decreased soil profile water and NO−3‐N contents, and increased ammonium N in that part of the soil profile near the manure‐soil interface. Clay loam over clay loam retained more salt but was slower than sand over sand in promoting desired changes and decrease of NO−3‐N. The other profile configurations had similar effects related to texture. The interaction effects of management by location or management by location by soil in either upper or lower fills were not important variables influencing shifts of soil characteristics.
Nitrogen‐15 Determination of Nonrandomly Distributed Dinitrogen in Air
Authors: Craswell E. T. , Byrnes B. H. , Holt L. S. , Austin E. R. , Fillery I. R. P. , Strong W. M. 
Published: July 2010

AbstractDinitrogen gas produced by denitrification of 15N‐enriched fertilizers does not achieve a random nitrogen (N) isotope distribution when mixed with atmospheric N2. Thus, such mixtures cannot be analyzed by the conventional mass spectrometric measurement of the 28 and 29 ion current ratio. A method is proposed which uses a high voltage arc passed between a pair of tungsten electrodes sealed in a glass vessel to fix some of the N2 as NOx species, and thereby redistribute the N isotopes of the N2 into an NOx pool. The NOx species are absorbed and oxidized by acidic permanganate, reduced to NH+4, and distilled by routine procedures. Since the are process redistributes the N isotopes randomly by ultimately converting the N to a monatomic species (NH+4), accurate isotope ratio analysis of the distilled samples by the conventional dual‐collector mass spectrometer method is possible. The method is precise, accurate, simple, inexpensive, and avoids many of the problems associated with direct 15N analysis of gas samples with nonrandom N isotopic distributions. This description of the basic methodology may enable direct measurement of denitrification losses from highly labeled fertilizer sources while its application to estimation of total denitrification losses requires additional methodologies not described in this paper.