bluuebunny/crossref_metadata_2025_split huggingface dataset:
Residual Fertilizer Nitrogen in a Flooded Rice Soil
Authors: Reddy K. R. , Patrick W. H. 
Published: July 2010

AbstractResidual effects of 15N‐labelled fertilizer (ammonium sulfate) nitrogen were measured during the second cropping season of rice (Oryza sativa L.). During the first cropping season, labelled fertilizer N was applied at 100 kg N/ha using different methods of N application. At the end of harvest the rice straw obtained during the first cropping season was incorporated back into the respective plots. During the second season half the plots were treated with an additional 100 kg N/ha of nonlabelled fertilizer N as an early season top dressing. The uptake of residual labelled N (that present in the native soil organic matter and in the incorporated rice straw) was measured during the growing season and at harvest time under fertilized and nonfertilized conditions.The recovery of residual labelled N in grain and straw was 2.7 to 3.1 kg N/ha, with a large fraction of N (34.3 to 40.1 kg N/ha) still remaining in the soil. Approximately 3 to 5 kg of the residual labelled N/ha present at the beginning of the season was not accounted for in any fraction and was assumed to be lost from the system. Over a 2‐year period, about 66 to 82% of the applied labelled fertilizer N could be accounted for by plant uptake or in the soil with the remainder lost from the plant‐soil system.
Sodium Bicarbonate Extraction to Estimate Nitrogen, Phosphorus, and Potassium Availability in Soils
Authors: Bar‐Yosef B. , Akiri B. 
Published: July 2010

AbstractThe extractability of NO3‐N, P, and K from five calcareous soils differing in physical and chemical characteristics by NaHCO3 (0.5M, pH 8.5) was studied under laboratory conditions. The extracted amounts of the three ions were related to time since their application to the soils, to the equilibration period of the soils with the extractants, to the concentration of the ions in the soils, and to the clay content of the soils. After about 70 days in the soil, the extractability of each ion at a given application level was independent of time. The recovery percentage of P and K as a function of the applied amounts of these elements depended mainly on the clay content of the soils, while NO3‐N recovery was independent of the factors studied. Linear relationships were obtained between NaHCO3‐and NH4OAc‐extracted K, and NaHCO3‐ and KCl‐extracted NO3‐N. The slopes for NO3‐N were 45° for all soils, but were specific for each soil in the case of K.
Erosion Processes on Steep Granitic Road Fills in Central Idaho
Authors: Megahan W. F. 
Published: July 2010

AbstractA set of thirty 20.2‐m2 (1/200‐acre) erosion plots was used to study erosion occurring on steep road fills constructed with granitic soil materials in the Idaho Batholith. Erosion data were collected for a 3½‐year period from 1969 through 1972. Erosion on bare control plots averaged 3.4 metric tons/km2 per day for water years 1970 through 1972. Erosion was reduced an average of 44% and 95% by tree planting and straw mulching, respectively. Daily erosion rates were consistently higher during summer periods than during snowfree winter periods, presumably because of greater rainfall energy during the summer. Dry creep accounted for at least 15% of the total annual erosion for the years sampled and was as high as 40% in 1971. The erodibility index was a poor predictor of erosion for rain periods. Observations in the area suggest that wind was an important erosion factor on the steep slope studied. The median particle size of eroded materials (D50) tended to decrease throughout the summer and fall until mid‐October when it abruptly increased. Soil crusting during the summer and soil freezing and thawing in the fall may have caused these seasonal trends.
Weathering of Micas by Mycorrhizal Soybean Plants
Authors: Mojallali H. , Weed S. B. 
Published: July 2010

AbstractTwo biotites, a phlogopite, and a muscovite, ground to yield sandsize flakes, were used as sources of K for soybeans [Glycine max (L.) Merrill] grown in pot culture with and without vesicular‐arbuscular mycorrhizal association. On the low‐fertility soil used, effects of the mycorrhizae were most pronounced in terms of P uptake. Plants in noninoculated pots were stunted and P deficient; no K deficiency was observed in these plants. Plants grown in inoculated soil were larger and did not exhibit P deficiency symptoms; they were, however, K deficient. When P deficiency was corrected, there was no difference in plant growth attributable to K source, though the micas differed markedly in their abilities to supply soluble K. The mycorrhizae appeared to accelerate weathering of the biotites and the phologopite, but no effect was observed on the muscovite. Electron microprobe analysis showed extensive removal of K and some removal of Al from edges of the readily weathered biotite flakes subjected to biological weathering.
Effect of Fulvic Acid on Adsorption of Methyl Parathion and Parathion by Ca2+ − and Fe3+‐Montmorillonite Suspensions.
Authors: Bowman Bruce T. 
Published: July 2010

AbstractA study was conducted to examine the effect of fulvic acid (FA) on the adsorption of methyl parathion and parathion by Ca2+ − and Fe3+‐montmorillonite suspensions, and to determine whether FA in solution could alter the water solubility of these insecticides. FA, in the 10‐ to 100‐mg/liter range, did not affect the water solubility of the two insecticides. In Ca2+‐montmorillonite suspensions, increasing FA concentrations first enhanced methyl parathion adsorption, followed by adsorption decrease at higher FA levels. Methyl parathion adsorption in Fe3+‐montmorillonite suspensions decreased, with increasing FA levels. Parathion adsorption was not significantly altered in either clay suspension. The order in which the FA, clay, and insecticide were mixed affected methyl parathion adsorption. The greatest effects were observed where FA was adsorbed by the clay before the insecticide solutions were added. FA adsorption by Ca2+‐montmorillonite fitted the Freundlich isotherm, whereas the much greater adsorption by Fe3+‐montmorillonite fitted the Langmuir isotherm. Although both CaCl2 and FeCl3 solutions greatly enhanced FA removal by their respective clay suspensions (even at low concentrations), parathion adsorption was not affected. The presence of FA in the FeCl3‐Fe3+‐montmorillonite suspensions appeared to prevent parathion degradation.
Organic Phosphorus Changes Over a Growing Season in Some Borolls and Associated Aquoll of South Dakota
Authors: Westin Frederick C. 
Published: July 2010

AbstractThe objective of this research was to study changes in soil organic phosphorus for five members of a soil catena over a growing season. Three horizons of each of five pedons were sampled on the South Dakota University Research Farm at 2‐week intervals 10 April–23 October. Samples were taken at noon each sampling date when temperatures were recorded using a dial thermometer. Precipitation was that recorded by the Research Farm gauge between sampling periods. Soil samples were analyzed for total and organic‐P, available‐P and pH. The pedons also were analyzed for CEC, exchangeable cations, total nitrogen and organic carbon. Catena members appeared to have seasonal changes in organic phosphorus but the change was significant only for the north‐facing member. When examined for each sampling date the organic phosphorus changes were significantly related to precipitation for the sloping Borolls but not in the Borolls occupying level positions nor the associated Aquoll.
Cesium Sorption and Desorption Behavior of Kaolinites
Authors: Komarneni Sridhar 
Published: July 2010

AbstractData for three kaolinites show that Cs was preferentially sorbed by kaolinites in NaCl and CaCl2 solutions. Cesium desorption behavior of kaolinites revealed that a variable proportion, 0–3.5% was strongly held. The Cs desorption behavior as well as the amounts of Cs fixed by kaolinites correlated well with the nature of impurities in them.
Determining Soil Gypsum Content and Expressing Properties of Gypsiferous Soils
Authors: Nelson R. E. , Klameth L. C. , Nettleton W. D. 
Published: July 2010

AbstractThe standard method for measuring the gypsum content of soils is a lengthy one, partly because of the presence of Na and Mg sulfates in most gypsic horizons, and partly because of the difficulty in dissolving all the gypsum in the sample. A more rapid method, sufficiently accurate for taxonomic uses, has been developed and is based on loss of crystal water of gypsum upon heating to 105° C. Percent gypsum, calculated on an oven‐dry weight basis from loss of crystal water, equals 1.038 × percent gypsum by the standard chemical method + 0.17. The standard error of estimate for the new method is ± 1.8% gypsum. Equations are given for expressing properties of gypsiferous soils on an oven‐dry + crystal water of gypsum weight basis.
Electron Probe Microanalytical Studies of Phosphorus Distribution within Soil Fabric
Authors: Qureshi R. H. , Jenkins D. A. , Davies R. I. 
Published: July 2010

AbstractElectron probe microanalysis has been used to follow the distribution of phosphorus and associated elements within soil features to establish the composition of the immediate root environment. Various qualitative analytical modes of using the instrument are described involving either specimen traverse or spectrometer scanning with a static beam, line scanning, one‐dimensional scanning, area scanning, or successive rast counting. By these means phosphorus has been found to occur variously as discrete grains of rare‐earth phosphates, in preferential association with iron in iron/manganese concretions, as concentrations within undifferentiated soil matrix and ferrans at void surfaces, and to be associated with calcium in a fresh root and possibly with iron rather than calcium, aluminium, or potassium in an old root.
Cation Exchange Equilibria in a Mixed Soil System Containing Three Heterovalent Cations
Authors: Wiedenfeld R. P. , Hossner L. R. 
Published: July 2010

AbstractCation exchange equations used with soils have been suitable only for systems containing two cations. Theoretical exchange equilibria relationships for a mixed soil system containing three heterovalent cations; Ca2+, Mg2+, and Na+; are presented. Predictive equations for this tertiary system are derived using solid phase activity coefficients and thermodynamic equilibrium constants for the three binary systems obtained from experimental data. Theoretical cation exchange equilibria described for this tertiary system are in agreement with recognized exchange properties for these three cations. Interactions between two cations as they affect the exchange behavior of a third cation are also predicted. The methods presented are applicable to systems containing any number of heterovalent cations.
Decomposition in Soil of the Humic Acid‐type Polymers (Melanins) of Eurotium echinulatum, Aspergillus glaucus Sp. and Other Fungi
Authors: Linhares L. F. , Martin J. P. 
Published: July 2010

AbstractStudies were conducted to compare the decomposition rates in soil of 14C‐labeled humic acid‐type polymers (melanins) of Eurotium echinulatum and Aspergillus glaucus sp. with those of other fungal melanins, soil and peat humic acids, fungal cells, nondialysable culture medium polymers not precipitated by acid, and other organic residues. Carbon and N contents, COOH groups, and total acidity were also determined for the fungal products. After 12 weeks incubation at 22°C the percentages of the added 14C activity evolved as 14CO2 from the acid‐precipitable fungal melanins ranged from 4–6% for E. echinulatum, 4–13% for A. glaucus, 6–8% for Hendersonula toruloidea and 6 to 50% for Stachybotrys atra. The fungal polymers were almost as resistant to biodegradation as soil or peat humic acids. The fungal cells and culture medium polymers not precipitated by acid lost from 26–58% of the applied C, which compared with losses of 50–75% for hyaline fungal cells, corn stalks, and wheat straw. The N source and growth conditions did not influence biodegradability. The C contents of the melanins ranged from 51–60%, the N from 1.4–6.8%, COOH groups from 81–385 meq/100g, and total acidity from 375–876 meq/100 g.
Field Testing of Several Nitrogen Availability Indexes
Authors: Fox R. H. , Piekielek W. P. 
Published: July 2010

AbstractWith no quick, reliable soil N availability test for humid region soils, N fertilizer recommendations in these areas are being made on the basis of crop N requirements. When the variability in N‐supplying capability of soils is not taken into account, most N fertilizer recommendations will be inaccurate, leading to inefficient use of N, less economical crop production, and the potential for N pollution of the nation's air and water. Although several N availability indexes have proved to be well correlated with the N‐supplying capability of a soil in greenhouse or laboratory experiments, very little testing of these indexes has been done with field experiments. Eight N availability indexes were correlated with the capability of eight Pennsylvania soils to supply N to field‐grown corn (Zea mays L.) in 1976 and 1977. Boiling 0.01M CaCl2 and 0.01M NaHCO3‐extractable N were both significantly correlated at the 1% level (r = 0.86 and 0.77, respectively) with the N‐supplying capability of the soils from the combined 1976 and 1977 experiments. Autoclave‐extractable NH4‐N and total soil N were significantly correlated with the soil supplying capability at the 5% confidence level (r = 0.70 and 0.68, respectively). Walkley‐Black soil organic matter, soil NO3‐, and H2SO4‐extractable and KCl‐extractable N were not significantly correlated with N availability in the field. Though four of the indexes were well correlated with the N availability in the soil, time and expense necessary for these analyses may preclude their being used routinely by soil testing laboratories.
Mottling in Soil Profiles Containing a Coarse‐textured Horizon
Authors: Clothier B. E. , Pollok J. A. , Scotter D. R. 
Published: July 2010

AbstractMottling often characteristically occurs in fine‐textured soil just above an underlying coarse‐textured layer. Interpretation of such mottling as representing a normal drainage impedance is misleading as a perched or ground water table may never occur in the profile. In this paper a simple soil water drainage model is discussed that aids interpretation of the pattern of mottling in a soil horizon above a coarse‐textured layer. Also the influence of various soil physical parameters on mottling phenomena is analyzed, suggesting that the more coarse‐textured the underlay the greater the propensity to mottle. The tendency to mottle is shown to be greatest in the soil immediately above the coarse‐textured layer. The model is applied to the naturally‐layered Manawatu fine sandy loam, a Dystric Fluventic Eutrochrept.
Determination of the Apparent Dispersion Coefficient of Solutes in Unsaturated Soil
Authors: Paetzold R. F. , Scott H. D. 
Published: July 2010

AbstractA method for determining the apparent dispersion coefficient of a solute in unsaturated soils at relatively low soil water flow rates is presented. Two soil cores with different initial water contents were joined and water allowed to flow between the soil cores for a specified time interval. The distribution of a radioactively tagged solute, initially present in one of the soil cores, was subsequently determined by freezing the cores in liquid air, sectioning the soil with a refrigerated microtome, and analyzing the soil sections for solute content using liquid scintillation techniques. Apparent dispersion coefficients could be determined either with or against the water flow. The solutes used in this study were tritiated water, chloride, and metribuzin (a herbicide).
Surface Charge Manipulation in Constant Surface Potential Soil Colloids: II. Effect on Solute Transport
Authors: Wann S. S. , Uehara G. 
Published: July 2010

AbstractPotassium breakthrough curves from soil columns containing samples collected from an oxic horizon of a Typic Torrox shifted to the right as the sample was treated with increasing levels of P. The shift in the breakthrough curve was significantly related to a lowering of the zero point of charge. The lowering of the zero point of charge was in turn related to levels of applied P. The anion accompanying K also had a marked effect on the position of the breakthrough curve. When the accompanying anion was Cl, S, and P respectively, the K concentration in the effluent attained one‐half of influent concentration at 4.25, 5.30, and 8.20 pore volumes.
Long‐Term Denitrification Studies in Soils Fertilized With (15NH4)2SO4
Authors: Focht D. D. , Stolzy L. H. 
Published: July 2010

AbstractA 2‐year study was conducted in lysimeters containing four different soils with successive summer and winter crops of corn and barley, respectively. The crops were fertilized with (15NH4)2SO4 at application rates equivalent to 134, 108, 415, and 440 Kg N/ha for the respective summer 1973, winter 1974, summer 1974, and winter 1975 crops. The frequency of 15N dinitrogen samples was higher in the summer and higher at the lower fertilizer rates, while the reverse was true for NO3‐ concentrations in leach water and N2O concentrations in the soil profile. Emissions of N2O from soil, even where the higher concentrations were observed, were low in terms of N losses with the greatest mass emission at any time amounting to 6.5 g/ha over a 1‐day period. Nitrogen gas emissions over a 1‐week period in one instance were estimated at 5.2 kg N/ha: it was observed that this amount could be generated from low (1 ppm or less) concentrations of N2O.
Residual Nitrate‐N in Fine Sand as Influenced By N Fertilizer and Water Management Practices
Authors: Smika D. E. , Watts D. G. 
Published: July 2010

AbstractA better understanding of the severity of NO3‐N movement out of the crop root zone in irrigated sandy soils is needed. The objective of this study was to determine residual NO3‐N after the corn (Zea mays L.) growing season from N applied at rates of (i) 112, (ii) 224, and (iii) 336 kg/ha in 1974 and (iv) 168, (v) 250, and (vi) 324 kg/ha in 1975. Nitrogen was applied as a single broadcast (B) application at the beginning of the corn growing season or injected (S) through the irrigation system at five equal increments before tasseling. Water application for both N application methods was attempted to be 0.8 W2 water application treatment, residual NO3‐N averaged 0.22 kg/during all but the first 6 weeks of corn growth.When N was broadcast‐applied at seeding very little residual NO3‐N remained in the 150‐cm sampling depth after the crop growing season, regardless of N application rate or water application amount. When the N was applied through the irrigation system (injected N), only the W3 water application treatment resulted in leaching all NO3‐N below the crop root zone. With injected N and W2 water application treatment, residual NO3‐N averaged 0.22 kg/ha for each kg/ha of N applied. With injected N and W1 application treatment NO3‐N increased linearly at 0.43 kg/ha for each kg/ha of applied N above the B4 rate. At lower N application rates, residual NO3‐N was very low because this amount of N nearly equalled plant uptake. No overwinter NO3‐N was lost with the injected N treatments. These results showed that the injected N application method with proper water application management can greatly reduce the potential for NO3‐N movement below the corn crop rooting zone on fine sand soils.
Copper Chloride as an Extractant for Estimating the Potentially Reactive Aluminum Pool in Acid Soils
Authors: Juo A. S. R. , Kamprath E. J. 
Published: July 2010

AbstractThe reactive Al pool in selected Ultisols, Oxisols, and Histosols from Africa, South America, and North Carolina was estimated by extraction with 1N CuCl2. The Al‐saturated clay minerals with and without interlayered hydroxy‐Al were used to compare the extractability of Al by 1N CuCl2 and 1N KCl.The 1N solutions of KCl and CuCl2 were equally effective in extracting exchangeable Al from an Al saturated montmorillonite. The 1N CuCl2 solution, however, extracted almost twice as much Al from an Al saturated vermiculite containing a hydroxy Al interlayer as compared with 1N KCl. Generally, more than twice as much Al was extracted from acid surface soils (< pH 5) by 1N CuCl2 than by 1N KCl suggesting that Al bound by organic matter was being extracted by the CuCl2.
Direct Measurement of Denitrification Loss from Soils: I. Laboratory Evaluation of Acetylene Inhibition of Nitrous Oxide Reduction
Authors: Ryden J. C. , Lund L. J. , Focht D. D. 
Published: July 2010

AbstractThe rate and extent of denitrification in soils incubated under helium atmospheres in the presence of acetylene (C2H2) concentrations ranging from 0.1 to 5.0% (vol/vol) was equivalent to that measured in the absence of C2H2. In the absence of C2H2, gaseous nitrogen (N) appeared as a mixture of nitrous oxide (N2O) and dinitrogen (N2), usually dominated by N2, whereas in the presence of C2H2 gaseous N appeared exclusively as N2O. An C2H2 concentration of 1.0% was also sufficient to maintain inhibition of N2O reduction even when the soil nitrate supply had been exhausted. Overall respiration of incubation systems, measured as carbon dioxide evolution, was also unaffected by the presence of C2H2. Similar findings were obtained when soils were incubated under argon‐oxygen (4:1) atmospheres containing 1.0% C2H2. The inhibitory effect of C2H2 was virtually instantaneous when a 1.0% C2H2 concentration was established in an actively denitrifying soil. Diffusion of C2H2 into soils packed to their maximum bulk density and held at 5% air‐filled porosity was also sufficiently rapid to induce essentially complete inhibition of N2O reduction during incubation in air using a 15N‐labeled nitrate addition to the soil. The extent of denitrification varied among soils and ranged from 54 to 154 µg N/g under helium atmospheres, and from 15 to 106 µg N/g under argon‐oxygen atmospheres, after 200 hours incubation. Ratios of N2/N2O were essentially the same whether measured directly or calculated from the difference in N2O production in the presence and absence of C2H2. The findings are discussed with respect to the use of the C2H2 inhibition technique for direct infield measurement of denitrification.
A Reevaluation of Phosphorus‐32 and Resin Methods in a Calcareous Soil
Authors: Bowman R. A. , Olsen S. R. 
Published: July 2010

AbstractFour experiments were run to evaluate the resin and 32P methods as valid laboratory methods in a calcareous soil. Recovery of four levels of added KH2PO4, after several cycles of wetting, drying, and mixing was evaluated. Total‐exchangeable P (TEP24) was determined by the carrier‐free method, and resinextractable P by equilibrating 1 g soil sample with 2 g resin overnight. Equilibrium of 31P and 32P on the soil‐solid phase was evaluated by measuring specific activities with time. Different soil‐solution ratios, using water and 0.01M CaCl2 as extractants, were evaluated to determine their effects on the total exchangeable P. Water and four different salts at three different molarities were used as extractants with 1 and 2 g resin to determine total released P in solution and on the resin.The recovery experiment showed a high correlation between added and recovered P, using both TEP24 and resin methods; the time‐equilibration study indicated a lack of complete equilibrium between 31P and 32P after 2 hours shaking, and a near complete or complete equilibrium at 24 hours; different soil‐solution ratios did not affect total exchangeable P, and water extracted the most resin‐P and 0.01M CaSO4 the least (roughly one‐half of pure water):