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Martínez-Gil, Ana, Maria del Alamo-Sanza, Rosario Sánchez-Gómez e Ignacio Nevares. "Different Woods in Cooperage for Oenology: A Review". Beverages 4, n. 4 (23 novembre 2018): 94. http://dx.doi.org/10.3390/beverages4040094.
Abstract (sommario):
Contact of wine with wood during fermentation and ageing produces significant changes in its chemical composition and organoleptic properties, modifying its final quality. Wines acquire complex aromas from the wood, improve their colour stability, flavour, and clarification, and extend their storage period. New trends in the use of barrels, replaced after a few years of use, have led to an increased demand for oak wood in cooperage. In addition, the fact that the wine market is becoming increasingly saturated and more competitive means that oenologists are increasingly interested in tasting different types of wood to obtain wines that differ from those already on the market. This growing demand and the search for new opportunities to give wines a special personality has led to the use of woods within the Quercus genus that are different from those used traditionally (Quercus alba, Quercus petraea, and Quercus robur) and even woods of different genera. Thus, species of the genus Quercus, such as Quercus pyrenaica Willd., Quercus faginea Lam., Quercus humboldtti Bonpl., Quercus oocarpa Liebm., Quercus frainetto Ten, and other genera, such as Robinia pseudoacacia L. (false acacia), Castanea sativa Mill. (chestnut), Prunus avium L. and Prunus cereaus L. (cherry), Fraxinus excelsior L. (European ash), Fraxinus americana L. (American ash), Morus nigra L, and Morus alba L. have been the subject of several studies as possible sources of wood apt for cooperage. The chemical characterization of these woods is essential in order to be able to adapt the cooperage treatment and, thus, obtain wood with oenological qualities suitable for the treatment of wines. This review aims to summarize the different species that have been studied as possible new sources of wood for oenology, defining the extractable composition of each one and their use in wine.
2
Каретникова (Karetnikova), Наталья (Natal'ja) Викторовна (Viktorovna), Лариса (Larisa) Валерьевна (Valer'evna) Чендылова (Chendylova) e Роберт (Robert) Зусьевич (Zus'evich) Пен (Pen). "DELIGNIFICATION OF FLAX SHIVE". chemistry of plant raw material, n. 1 (23 novembre 2017): 155–62. http://dx.doi.org/10.14258/jcprm.2018012757.
Abstract (sommario):
Delignification of the flax shive (wastes of oakum and heat insulation production) was studied. Chemical composition of the work material (mass parts in percents from the bone-dry material): cellulose 30,7, lignin 33,1, pentosans 28,0, extractable by organic solvent 4,3, extractable by hot water 5,4, ash 1,7. The flax shive was delignificated in laboratory condition by means of peracetic acid, hydrogen peroxide and sulfate cooking solution. The conditions of peracetic pulping: initial mass part of the «icy» acetic acid in cooking solution 0,65, perhydrol 0,35, the catalyst concentration (sodium tungstate) 0,03 g-mol/dm3, liquid module 6, temperature 92 °C; pulp yield 46,1% without of undercooked pulp. The conditions of peroxide pulping: initial concentration of hydrogen peroxide 17%, liquid module 6, complex catalyst concentration 0,1 g-mol/dm3 (molar parts of the Na2WO4, Na2MoO4 and H2SO4 in catalyst composition are 0,3 : 0,3 : 0,4 accordingly), temperature 98 °C; pulp yield 45,8% without undercooked pulp. The conditions of sulfate pulping: initial concentration of active alkali 55 g/dm3 (in Na2O unit), degree of sulfidity 18%, liquid module 4, temperature 170 °C; pulp yield 32,3% without undercooked pulp. Samples of the technical cellulose, received by oxidizing methods, excel sulphate cellulose in relation to yield, ability for milling, whiteness and mechanical properties (except for tear). On the set of normalized properties they approach to characteristic of kraft bleached pulp from deciduous woods and can be considered as perspective stringy half-finished for production of the paper sanitary-household and hygienic purpose.
3
Kelsey, Rick G., e Mark E. Harmon. "Distribution and variation of extractable total phenols and tannins in the logs of four conifers after 1 year on the ground". Canadian Journal of Forest Research 19, n. 8 (1 agosto 1989): 1030–36. http://dx.doi.org/10.1139/x89-157.
Abstract (sommario):
Concentrations of extractable total phenols and tannins have been analyzed in the outer bark, inner bark, sapwood, and heart wood from logs of four conifer species, after 1 year on the ground. To estimate decay rates, initial tissue densities were compared with those after 1 and 2 years of decomposition. The four species studied, Pacific silver fir (Abiesamabilis Dougl. ex Forbs), western hemlock (Tsugaheterophylla (Raf.) Sarg.), Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco), and western red cedar (Thujaplicata D. Don) represent a gradient of decay resistance. Within a species, outer bark contained the greatest quantities of extractable total phenols followed by inner bark, heart wood, and sapwood. Outer barks also had the highest extractable tannin concentrations. Woody tissues contained very low concentrations of tannin compared with the barks. Total phenol concentrations were highest in the heart wood of red cedar, the most resistant, and lowest in the heart wood of silver fir, the least resistant. There was no obvious relationship between tannins, in any tissues, and the resistance gradient. Density measurements indicated minimal decay in all tissues after 1 year. At 2 years, the inner barks of Douglas-fir, western hemlock, and silver fir had decreased significantly. In general, tissues with the highest extractable phenols appear to be decomposing most slowly.
4
Chen, Y., e T. C. Bond. "Light absorption by organic carbon from wood combustion". Atmospheric Chemistry and Physics Discussions 9, n. 5 (30 settembre 2009): 20471–513. http://dx.doi.org/10.5194/acpd-9-20471-2009.
Abstract (sommario):
Abstract. Carbonaceous aerosols affect the radiative balance of the Earth by absorbing and scattering light. While BC is highly absorbing, some organic compounds also have significant absorption, which is greater at near-ultraviolet and blue wavelengths. To the extent that OC absorbs visible light, it may be a non-negligible contributor to direct aerosol radiative forcing. In this work, we examine absorption by primary OC emitted from solid fuel pyrolysis. We provide absorption spectra of this material, which can be related to the imaginary refractive index. This material has polar character but is not fully water-soluble: more than 92% was extractable by methanol or acetone, compared with 73% for water and 52% for hexane. Water-soluble organic carbon contributed to light absorption at both ultraviolet and visible wavelengths. However, a larger portion came from organic carbon that is extractable only by methanol. The spectra of water-soluble organic carbon are similar to others in the literature. We compared spectra for material generated with different wood type, wood size and pyrolysis temperature. Higher wood temperature is the main factor creating organic aerosol with higher absorption, causing about a factor of four increase in mass-normalized absorption at visible wavelengths. A simple model suggests that, despite the absorption, both high-temperature and low-temperature carbon have negative climate forcing over a surface with average albedo.
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Chen, Y., e T. C. Bond. "Light absorption by organic carbon from wood combustion". Atmospheric Chemistry and Physics 10, n. 4 (16 febbraio 2010): 1773–87. http://dx.doi.org/10.5194/acp-10-1773-2010.
Abstract (sommario):
Abstract. Carbonaceous aerosols affect the radiative balance of the Earth by absorbing and scattering light. While black carbon (BC) is highly absorbing, some organic carbon (OC) also has significant absorption, especially at near-ultraviolet and blue wavelengths. To the extent that OC absorbs visible light, it may be a non-negligible contributor to positive direct aerosol radiative forcing. Quantification of that absorption is necessary so that radiative-transfer models can evaluate the net radiative effect of OC. In this work, we examine absorption by primary OC emitted from solid fuel pyrolysis. We provide absorption spectra of this material, which can be related to the imaginary refractive index. This material has polar character but is not fully water-soluble: more than 92% was extractable by methanol or acetone, compared with 73% for water and 52% for hexane. Water-soluble OC contributes to light absorption at both ultraviolet and visible wavelengths. However, a larger portion of the absorption comes from OC that is extractable only by methanol. Absorption spectra of water-soluble OC are similar to literature reports. We compare spectra for material generated with different wood type, wood size and pyrolysis temperature. Higher wood temperature is the main factor creating OC with higher absorption; changing wood temperature from a devolatilizing state of 210 °C to a near-flaming state of 360 °C causes about a factor of four increase in mass-normalized absorption at visible wavelengths. A clear-sky radiative transfer model suggests that, despite the absorption, both high-temperature and low-temperature OC result in negative top-of-atmosphere radiative forcing over a surface with an albedo of 0.19 and positive radiative forcing over bright surfaces. Unless absorption by real ambient aerosol is higher than that measured here, it probably affects global average clear-sky forcing very little, but could be important in energy balances over bright surfaces.
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Loehr, R. C., L. A. Rogers e D. C. Erickson. "Mobility of Residues at Petroleum Industry Hazardous Waste Land Treatment Sites". Water Science and Technology 25, n. 3 (1 febbraio 1992): 191–96. http://dx.doi.org/10.2166/wst.1992.0092.
Abstract (sommario):
This study determined: (a) waste constituents remaining at long-term hazardous waste land treatment (HWLT) sites, and (b) the potential for subsequent degradation and migration of these constituents. Soils from six depths from random test pits at two oil refinery sites and a wood preserving site were evaluated for specific metals and organics. In surface soils, concentrations of organics and metals were greater than in background soils. At depths below 24-30” (60-76 cm) at the HWLT sites, PAH concentrations were below detection limits and the freon-extractable concentrations were at background. Chromium and nickel at depths below 24” (60 cm) appeared greater than background soil concentrations, but not copper, lead, and zinc concentrations. Organics in TCLP extracts of site soils indicated no PAH compounds were extracted from either weathered or non-weathered soils. In most of the site soil samples, metals in the TCLP extracts were close to or below detection limits of 0.1 mg/L. Aerobic and anaerobic microcosm studies indicated no statistically significant degradation of the PAH and freon extractables in the surface soil samples over eight months, suggesting very slow degradation of the accumulated organics following closure of an HWLT site.
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Stevens, Robert K., C. W. Lewis, T. G. Dzubay, L. T. Cupitt e Joellen Lewtas. "Sources of Mutagenic Activity in Urban Fine Particles". Toxicology and Industrial Health 6, n. 5 (ottobre 1990): 81–94. http://dx.doi.org/10.1177/074823379000600506.
Abstract (sommario):
Samples were collected during the winter of 1984—1985 in the cities of Albuquerque, NM and Raleigh NC as part of a US Environmental Protection Agency study to evaluate methods to determine the emission sources contributing to the mutagenic properties of extractable organic matter (EOM) present in fine particles. Data derived from the analysis of the composition of these fine particles served as input to a multi-linear regression (MLR) model used to calculate the relative contribution of wood burning and motor vehicle sources to mutagenic activity observed in the extractable organic matter. At both sites the mutagenic potency of EOM was found to be greater (3—5 times) for mobile sources when compared to wood smoke extractable organics. Carbon-14 measurements which give a direct determination of the amount of EOM that originated from wood burning were in close agreement with the source apportionment results derived from the MLR model.
8
LaZerte, Bruce, e Joe Findeis. "Acidic leaching of a Podzol Bf horizon from the Precambrian Shield, Ontario, Canada". Canadian Journal of Soil Science 74, n. 3 (1 agosto 1994): 321–33. http://dx.doi.org/10.4141/cjss94-045.
Abstract (sommario):
Illuviated mineral horizons (Bf) from a Podzol on the Precambrian Shield, Ontario, Canada were collected, placed in columns and treated with distilled water, cation amended water, acidified water or cation and acid amended water over a 4-mo period. While the cation treatment had little effect relative to the control, the acid treatment removed large quantities of Al, Si and base cations. The source of the leached Al was primarily (~ 70%) dithionite–citrate–bicarbonate (DCB) extractable Al, apparently some form of amorphous gibbsite. Organic Al (pyrophosphate extractable) contributed only about 20%. However, even more pronounced was a major within-column migration of oxalate extractable Al–Si, perhaps allophane or imogolite, which was leached from the top of the acidified columns and precipitated below. The weathering of primary minerals and possibly interlayer Al in vermiculite contributed little to the leaching of Al from the acidified columns. Key words: Acid, weathering, Podzol, aluminum, silica
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CHUDE, V. O., G. O. OBIGBESAN e N. E. EGBE. "MICRONUTRIENT STATUS OF SELECTED CACAO-GROWING SOILS IN SOUTHWESTERN NIGERIA: PROFILE DISTRIBUTION OF TOTAL AND AVAILABLE ZINC". Canadian Journal of Soil Science 65, n. 1 (1 febbraio 1985): 21–24. http://dx.doi.org/10.4141/cjss85-003.
Abstract (sommario):
A study was conducted to determine the content and distribution of total 1.0 M NH4OAc-, 0.1 M HCl-, 1 M MgCl2-, and 0.005 M DTPA-extractable Zn in the genetic horizons of 16 soil profiles from major cacao-growing areas in Southwestern Nigeria. The content of total Zn for all the soils varied from 12 to 92 μg/g with soils derived from igneous and metamorphic rocks containing more than those of sedimentary origin. Most of the soils had the highest concentration of total Zn in the surface horizons. There was a strong association between total Zn and organic matter, total Zn and silt/clay content. The 1 M NH4OAc-, 0.1 M NCl-, 1 M MgCl2- and 0.005 M DTPA-extractable Zn in all the soils and horizons varied from 0.17 to 5.6, from 0.06 to 2.37, from 0.20 to 1.20 and from 0.022 to 1.14 μg Zn/g, respectively. The NH4OAc generally removed more Zn than the other three extractants. The amount of Zn extracted showed a general decrease with depth. A significant amount of MgCl2-extractable Zn appeared to be associated with silt content while soil pH influenced the quantity of Zn extracted by the NH4OAc method. Key words: Total Zn, NH4OAc-extractable N, HCl-extractable N, MgCl2-extractable N, DTPA-extractable Zn, soil profile
10
Osman, Noridah B., Armando G. McDonald e Marie-Pierre G. Laborie. "Analysis of DCM extractable components from hot-pressed hybrid poplar". Holzforschung 66, n. 8 (1 dicembre 2012): 927–34. http://dx.doi.org/10.1515/hf-2012-0011.
Abstract (sommario):
Abstract The effects of thermal compression on the organic-soluble material of a uniform wood substrate, hybrid poplar (clone OP-367), has been studied. Poplar veneers were preconditioned to 0% or 8% moisture content and subsequently hot pressed at 150°C, 200°C, and 250°C. The dichloromethane (DCM) extracts were characterized by various hyphenated analyses [gas chromatography-mass spectrometry (GC-MS), analytical pyrolysis (Py-GC-MS), electrospray ionization-mass spectrometry (ESI-MS), and gel permeation chromatography (GPC)]. The yields and composition of extractable compounds were markedly influenced by treatment at 250°C compared to those obtained at lower temperatures. Most importantly, the organic extracts contained a significant portion of lignin-derived compounds after treatment at 250°C.
11
MARTIN, DALE E., e L. E. LOWE. "CHARACTERIZATION AND CLASSIFICATION OF ROOT MAT HORIZONS IN SOME COASTAL BRITISH COLUMBIA PODZOLS". Canadian Journal of Soil Science 69, n. 1 (1 febbraio 1989): 17–23. http://dx.doi.org/10.4141/cjss89-002.
Abstract (sommario):
Podzols formed in high-rainfall areas of south coastal B.C. often have layers of highly organic material at depth in the profile, and in many cases, “pipes” of similar material angling down through the profile. These materials have a greasy feel, few discernible mineral grains, occasional remnants of wood structure and a cellular nature. The horizontal layers, termed "root mats", range in thickness from 1 cm to > 30 cm, and are overlain by coarse-textured material of low organic matter content. Chemically this material is similar to surficial H horizons with respect to C:N and N:S ratios, but closely resembles Podzolic B horizons with respect to Fe content and humus fraction ratios. In contrast oxalate-extractable Al values are remarkably high, sometimes exceeding 10%. The majority of the root mats can be classified as organic (> 17% organic C), either as H or O horizons. Those containing < 17% C meet the criteria for Bhf horizons. Key words: Root mat, root channel, oxalate-extractable Al, organic horizons
12
Haney, R. L., A. J. Franzluebbers, F. M. Hons e D. A. Zuberer. "Soil C extracted with water or K2SO4: pH effect on determination of microbial biomass". Canadian Journal of Soil Science 79, n. 4 (1 novembre 1999): 529–33. http://dx.doi.org/10.4141/s99-011.
Abstract (sommario):
Routine determination of soil microbial biomass C has shifted during the past decade from chloroform fumigation-incubation to chloroform fumigation-extraction using 0.5 M K2SO4 as extractant. We compared extractable C with water and 0.5 M K2SO4 in eight soils ranging in pH from 5.4 to 8.3. In unfumigated soils with low pH, extractable C was 0.8- to 1.2-fold greater with water than with 0.5 M K2SO4. However, in unfumigated soils with pH > 7.7, extractable C, although not statistically significant, was 11 to 19% less with water than with 0.5 M K2SO4. In fumigated soils, no difference in extractable C between water and 0.5 M K2SO4 was detected among soils with pH < 7.7, but extractable C was 13 to 17% less with water than with 0.5 M K2SO4 with pH > 7.7. Our results suggest that 0.5 M K2SO4 (1) may flocculate soil and cause adsorption of solubilized C onto colloids at pH < 7.7, but (2) may disperse calcareous soils at pH > 7.7, thereby differentially affecting the fate of solubilized C depending upon soil pH. Our results put into question the widespread adaptability of using chloroform fumigation-extraction to estimate microbial biomass C. Key words: Extractable carbon, chloroform fumigation-extraction, microbial biomass
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Walworth, J. L., M. T. Panciera e R. G. Gavlak. "Mehlich 3 extractant for determination of available B, Cu, Fe, Mn, and Zn in cryic Alaskan soils". Canadian Journal of Soil Science 72, n. 4 (1 novembre 1992): 517–26. http://dx.doi.org/10.4141/cjss92-043.
Abstract (sommario):
Field trials were conducted on three cryic soils in southcentral Alaska to determine the local suitability of the Mehlich 3 extractant. Mehlich 3 extractable B, Cu, Fe, Mn and Zn, DTPA-TEA extractable Cu, Fe, Mn and Zn, and hot water extractable B were measured on soils from factorial experiments with variable rates of B, Cu, Mn, and Zn. Additional soil samples from two B rate and liming studies in central Alaska were included in extractable B comparisons. Forage rape, broccoli, and potato tissue samples were collected from the factorial studies to determine relationships between soil- and plant-available micronutrients. Crop yields were not affected by micronutrient applications Neither Mehlich 3 nor DTPA-TEA extractant predicted plant-available Cu or Fe. Coefficients of determination between soil and plant tissue B were comparable for extraction by Mehlich 3 or hot water and ranged from 0.11 to 0.82 Neither the Mn nor Zn tests accounted for more than 39% of the observed tissue nutrient concentration variation. The inclusion of soil PH and organic matter slightly improved estimates of available B, Mn, and Zn. Mehlich 3 extractable Fe was poorly related to DTPA-TEA extractable Fe. Copper extracted with Mehlich 3 was related to that extracted with DTPA-TEA (r2 = 0.73); the inclusion of soil pH improved the relationship (r2 = 0.84). Mehlich 3 extractable Mn and Zn were closely related to DTPA-TEA extractable levels (r2 = 0.91 and 0.94, respectively). The correlation between Mehlich 3 and hot water B (r2 = 0.57) was significantly improved by including soil organic matter content (r2 = 0.71). Key words: Micronutrients, extractant, Mehlich 3, DTPA, hot water
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Neilsen, G. H., e E. J. Hogue. "Long-term effects of orchard soil management on tree vigor and extractable soil nutrients". Canadian Journal of Soil Science 72, n. 4 (1 novembre 1992): 617–21. http://dx.doi.org/10.4141/cjss92-052.
Abstract (sommario):
Bisbee Delicious apple trees on M.26 (Malus domestica Borkh.) rootstock were planted in 1982 on a neutral pH, loamy-sand soil and were subjected to five soil management-fertilizer regimes until 1989. Orchard floor vegetation control with herbicides was required to maximize tree growth. Annual application of P at 50 kg ha−1 and K at 100 kg ha−1 from 1984 to 1989 increased extractable soil P and K to the 40-cm depth but did not appear to increase tree vigor. Orchard floor vegetation maintained extractable soil Ca and Mg levels compared to vegetation control treatments. Key words: Orchard floor vegetation management, extractable soil P, K, Ca and Mg
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ROBERTS, T. L., e J. R. BETTANY. "THE INFLUENCE OF TOPOGRAPHY ON THE NATURE AND DISTRIBUTION OF SOIL SULFUR ACROSS A NARROW ENVIRONMENTAL GRADIENT". Canadian Journal of Soil Science 65, n. 3 (1 agosto 1985): 419–34. http://dx.doi.org/10.4141/cjss85-046.
Abstract (sommario):
The nature and distribution of forms of sulfur within the soil profile was studied in a climo-toposequence of soils from Saskatchewan. Total and soluble (CaCl2-extractable) inorganic SO4= generally increased with horizon depth. Calcium carbonate-associated SO4= accounted for up to 42% of subsoil S. Organic S decreased significantly with depth, as did the proportion of organic S occurring as organic SO4=. Amounts of total S, in surface and subsurface horizons generally increased from upper to lower slope positions. Organic SO4= in the surface horizons, as a proportion of the total S, decreased from upper to lower slope positions and across a narrow environmental gradient going from the arid Brown Chernozemic soils in the southwest to the more humid Gray Luvisols in the northeast. Key words: Total S, organic SO4=, CaCl2-extractable SO4=, HCl-extractable SO4=, profile distribution
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KRUGER, G. A., R. E. KARAMANOS e J. P. SINGH. "THE COPPER FERTILITY OF SASKATCHEWAN SOILS". Canadian Journal of Soil Science 65, n. 1 (1 febbraio 1985): 89–99. http://dx.doi.org/10.4141/cjss85-010.
Abstract (sommario):
A survey of the DTPA-extractable Cu levels of approximately 1000 fields representing a large number of soil types in Saskatchewan suggested that, under current cropping systems, Cu deficiencies appear to be concentrated in the Grey Soil Zone. They are especially probable in seven soil associations, which include light Transition of Grey and Brownish-Grey Podzolic soils. Soil criteria for detecting Cu deficiencies in cereal crops cannot be fully documented using conventional calibration tests and techniques. However, data from 21 field trials and a growth chamber study indicated that the critical level of DTPA-extractable Cu in these soils is approximately 0.4 mg∙kg−1 for cereals. Large spatial variability of DTPA-extractable Cu levels has been found to occur in a level field, thus suggesting that the Cu status of a field may not be adequately described by assessing the Cu levels of composite field samples. Key words: DTPA-extractable Cu, soil survey, critical level, spatial variability
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Hal Weiser, Alan Olness,, Bruce Kunze, Michael Lieser e Jana Rinke. "Differentiation of four northern Great Plains soils using resin extraction". Canadian Journal of Soil Science 84, n. 1 (1 febbraio 2004): 31–42. http://dx.doi.org/10.4141/s03-046.
Abstract (sommario):
Resin extraction of soils has revealed sensitivities of crops to the extractable V:(V + P) and Mg:(Mg + Ca) molar ratios. Consequently, we examined the Barnes and Buse soils in the northern Great Plains of North Dakota, South Dakota, and Minnesota. Svea and Langhei soils were included in the survey because of their close association. Samples of A or Ap horizons suspended in 20% ethanol were extracted with cation-(Na+) and anion-(NO) exchange resin-extractors for a period of 5 d. After equilibration, extractors were eluted with 1 N HCl and eluates were analyzed using inductively coupled plasma-atomic emission spectroscopy. Analytical concentrations were log transformed and analyzed using SAS PROC GLM. Each soil produced a distinct suite of extractable ions. Mean pH values ranged from about 6.8 for the Svea soil to about 8.0 for the Langhei soils. Total resin extractable Ca ranged from about 150 to 28 000 nmol g-1 soil and total resin extractable Mg ranged from 110 to 5500 nmol g-1 soil; the least amounts were found in the Svea soil and the greatest amounts were found in the Langhei soil. The pH of the Barnes and Buse soils and the amounts of extractable Ca and Mg in the Barnes and Buse soils were intermediate to those of the Svea and Langhei soils. Trivial amounts of V were detected in extracts from a few samples of Buse soils. Large fractions of S, B, and As in the Langhei soil were extracted on cation exchange resins presumably due to complex formation with the much larger amounts of Ca and Mg. Amounts of Ba, Sr, Fe, Co, Cu, and Si, detected in the extracts differed between soils with more being extracted from the Langhei than from the other soils. Only resin extractable Li and K differed from the general trend in that the amounts associated with Langhei soils were among the least. Detectable amounts of Al, Ni, and Zn usually were obtained but without differences between soils. Resin extractable P was correlated with bicarbonate extractable P but slopes of the regression lines differed between soils and two groups of Barnes soils were clearly distinguished in these relationships. Key words: extractable, nutrients, toxic elements, varadium, sulfur, phosphorus
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LaZerte, Bruce D., e Joe Findeis. "The relative importance of oxalate and pyrophosphate extractable aluminum to the acidic leaching of aluminium in Podzol B horizons from the Precambrian Shield, Ontario, Canada". Canadian Journal of Soil Science 75, n. 1 (1 febbraio 1995): 43–54. http://dx.doi.org/10.4141/cjss95-007.
Abstract (sommario):
Four Bf and one Bhf Podzol horizon samples from the Precambrian Shield, Ontario, Canada were leached with pH 3 solutions in three different experiments to determine which soil aluminum fraction was primarily responsible for the aluminum leached into solution. For the Bf horizons, it was primarily the oxalate-extractable aluminum fraction (corrected for pyrophosphate, Alo–Alp); for the Bhf horizon it was equally the pyrophosphate (Alp) and Alo–Alp. A comparison with other studies suggests that when the ratio (Alo–Alp)/Alp is above 0.3–0.7, the oxalate-extractable fraction will be most important, and at lower ratios the pyrophosphate fraction becomes most important. The pattern of fluoride leaching in these experiments suggests that F was concentrated primarily on the surface of the amorphous aluminum fraction. Key words: Aluminum, silica, fluoride, Podzol, acid deposition
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Neary, A. J., e S. R. Barnes. "The effect of sample grinding on extractable iron and aluminum in soils". Canadian Journal of Soil Science 73, n. 1 (1 febbraio 1993): 73–80. http://dx.doi.org/10.4141/cjss93-007.
Abstract (sommario):
Pyrophosphate-, dithionite- and acid ammonium oxalate-extractable Fe and Al are often measured on a finely ground aliquot of soil. Grinding provides a homogeneous sample from which a representative subsample can be obtained at sampling aliquots of less than 1 g. When a significant portion of the unground soil is greater than the sieve mesh size used when grinding, abrasion of primary minerals may cause increased levels of extractable Fe and Al. This study examined the distribution of extractable Fe and Al in some sandy soils and compared their levels in samples ground to < 500 μm and < 150 μm with those in unground < 2-mm soil. Samples ground to < 150 μm yielded the highest amounts of extractable Fe and Al. This effect was most prevalent when a motorized mortar and pestle was used. Samples ground to < 500 μm, which were frequently re-sieved to avoid over-grinding, contained similar amounts of extractable Fe and Al as the unground < 2-mm sample. If less than 1 g of soil is used for analysis, a sample manually ground to < 500 μm (35 mesh) is advisable and a protocol for sample grinding is recommended. Key words: Iron, aluminum, pyrophosphate, dithionite, oxalate, grinding
20
Barbour, Margaret M., T. John Andrews e Graham D. Farquhar. "Correlations between oxygen isotope ratios of wood constituents of Quercus and Pinus samples from around the world". Functional Plant Biology 28, n. 5 (2001): 335. http://dx.doi.org/10.1071/pp00083.
Abstract (sommario):
The oxygen isotope compositions of three wood constituents (the solvent-extractable portion, lignin and α-cellulose) were measured for samples collected from Quercus and Pinus trees around the world. Among Pinus samples all wood constituents were positively related to modelled δ18O of source water at the site, while among Quercus samples whole wood, lignin and α-cellulose showed positive relationships. The data support the hypothesis that many oxygen atoms in lignin exchanged with unenriched stem water during synthesis, rather than retaining the full isotopic signal from the molecular oxygen added during hydroxylation of the aromatic ring. The data also suggest that extraction of α-cellulose from wood samples is unnecessary for isotope studies looking at correlations with site parameters.
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Gasser, Ubald G., Stephan J. Juchler, Hans Sticher e William A. Hobson. "The fate of chromium and nickel in subalpine soils derived from serpentinite". Canadian Journal of Soil Science 75, n. 2 (1 maggio 1995): 187–95. http://dx.doi.org/10.4141/cjss95-026.
Abstract (sommario):
Weathering of serpentinitic parent material, naturally rich in both Cr and Ni, provides soils that generally contain elevated concentrations of both metals. In this study, soil development as well as the fate of Cr and Ni in Dystric Eutrochrepts derived from serpentinitic rock slide material were investigated in the Swiss Alps under subalpine climatic conditions. Exchangeable Ni was ≤ 0.2 mmol kg−1, but exchangeable Cr was always < 0.01 mmol kg−1. Linear correlation between dithionite-extractable Cr and Fe was positive, but negative between pyrophosphate extractable Cr and total soil carbon. Total Ni and Mg generally increased with depth. While most of the Cr was located in refractory primary minerals (pyroxene, garnet and spinels), a minor part was found in secondary Fe oxides; therefore, Cr tended to accumulate in the upper mineral part of the soil profiles and was generally less mobile than Ni. Soil Cr was not readily available for plant uptake. In some soils, exchangeable Ni reached concentrations potentially toxic to plants. Key words: Serpentinite, weathering, chromium, nickel, iron, subalpine zone
22
Wallace, J. L., K. P. Rioux, W. McKnight, L. Carter, D. Jourd'heuil, J. Meddings, B. J. Zimmerman, D. N. Granger e M. B. Grisham. "Hemoprotein-dependent production of a neutrophil-activating factor from arachidonic acid". American Journal of Physiology-Heart and Circulatory Physiology 263, n. 5 (1 novembre 1992): H1546—H1553. http://dx.doi.org/10.1152/ajpheart.1992.263.5.h1546.
Abstract (sommario):
Hemoproteins have been suggested to contribute to various forms of tissue injury by catalyzing the peroxidation of lipids. In this study, the ability of hemoglobin to catalyze the production of a neutrophil-activating factor from arachidonic acid was examined. Incubation of arachidonic acid, hydrogen peroxide, and hemoglobin at 37 degrees C for 30 min resulted in the production of a lipid-extractable substance that was chemotactic for neutrophils in vitro and could stimulate leukocyte adherence in vivo. These actions could be inhibited by two leukotriene B4 (LTB4) receptor antagonists. The peroxidation product cross-reacted significantly with an antibody directed against LTB4, but not with an antibody directed against LTC4. The production of this factor was hemoprotein dependent. Immunoreactive LTB4 and biological activity were produced only when hemoglobin, or another hemoprotein, cytochrome c, was present in the reaction mixture. The amount of the factor produced could be increased in a concentration-dependent manner by increasing the amounts of arachidonic acid or hydrogen peroxide in the reaction mixture. The production of this factor could be inhibited by 5-aminosalicylic acid, catalase, or deferoxamine. Separation of the lipid-extractable products of the peroxidation of arachidonic acid on high-performance liquid chromatography revealed that the immunoreactive (with anti-LTB4) and chemotactic substance had a retention time distinct from that of LTB4 and the hydroxyeicosatetraenoic acids. A lipid-extractable substance with significant cross-reactivity to anti-LTB4 could also be produced if plasma was substituted for arachidonic acid in the reaction mixture.(ABSTRACT TRUNCATED AT 250 WORDS)
23
Watanabe, Katsuji, e Koichi Hayano. "Source of soil protease in paddy fields". Canadian Journal of Microbiology 39, n. 11 (1 novembre 1993): 1035–40. http://dx.doi.org/10.1139/m93-157.
Abstract (sommario):
Properties of soil proteases and proteases from Bacillus spp. obtained from water-logged paddy fields treated with organic manure or chemical fertilizer or not treated with fertilizer were compared to elucidate the sources of soil proteases. The major extractable soil proteases were metal chelator sensitive neutral proteases that were active in hydrolyzing benzyloxycarbonyl-L-phenylalanyl-L-leucine and benzyloxycarbonyl-L-phenylalanyl-L-tyrosyl-L-leucine. In this respect they resembled extracellular proteases from Bacillus subtilis (six isolates), Bacillus cereus (four isolates), and Bacillus mycoides (three isolates) isolated from the same fields. The major extractable soil protease from the manured field was a serine neutral protease that was active in hydrolyzing casein. It resembled an extracellular protease from B. subtilis (eight isolates) isolated from the same field. Extractable soil proteases accounted for 18–96% of the total soil protease in the aforementioned soil. We concluded that a major source of soil protease in water-logged paddy fields is proteolytic Bacillus spp.Key words: soil protease, metal chelator sensitive neutral protease, serine neutral protease, proteolytic Bacillus spp.
24
SIMARD, R. R., T. E. BATES e L. J. EVANS. "EFFECTS OF CaCO3 AND P ADDITIONS ON CORN (Zea mays L.) GROWTH AND NUTRIENT AVAILABILITY OF A PODZOLIC SOIL". Canadian Journal of Soil Science 68, n. 3 (1 agosto 1988): 507–17. http://dx.doi.org/10.4141/cjss88-049.
Abstract (sommario):
A surface horizon from a Humo-Ferric Podzol was amended with 0 to 6 cmol kg−1 of CaCO3 and 125 to 500 mg P kg−1 to investigate their effects on the elemental composition and growth of corn and on nutrient availability. The addition of CaCO3 decreased the amounts of extractable P and Mn in the soil and the concentrations of P, K, Mn, Mg and Zn in the plants. The addition of P increased the dry matter yields, the amounts of available P in the soil and the concentrations of P and Mg in the plants, but decreased the concentrations of K, Mn and Zn in the seedlings. There were significant CaCO3 × P interactions on the amounts of extractable Mg and Zn in the soil and on the contents of N and Mn in the seedlings. The addition of 0.5 cmol CaCO3 kg−1 was beneficial to dry matter accumulation, but additions greater than 4 cmol kg−1 were excessive. The dry matter yields were most closely related to the amount of extractable P and to the activity of Mn2+ in solution. The concentration of P in the plants was very closely related to the amount of NaHCO3-extractable P in the soil. The concentration of Zn in the seedlings was most closely related to the amounts of DTPA-extractable Zn and of NaHCO3-extractable P. Key words: Liming, P fertilization, Zea mays (L.), plant nutrition, soil solution, Podzol
25
Zhang, T. Q., A. F. MacKenzie e B. C. Liang. "Long-term changes in Mehlich-3 extractable P and K in a sandy clay loam soil under continuous corn (Zea mays L.)". Canadian Journal of Soil Science 75, n. 3 (1 agosto 1995): 361–67. http://dx.doi.org/10.4141/cjss95-052.
Abstract (sommario):
Rates of change of soil nutrient levels during crop production can be used to evaluate the long-term economic value and sustainability of fertilizer practices. Objectives were to quantify changes in Mehlich-3 extractable P and K due to additions of inorganic and manure P and K in corn (Zea mays L.) production. Surface (0–20 cm) and subsoil (20–40 cm) samples were collected after harvest from 1984 to 1993 on a Chicot sandy clay loam soil (Grey Brown Luvisol) fertilized with two rates of inorganic P and K and with dairy manure. Manure P at 60 kg P ha−1 plus inorganic fertilizer P at 132 kg ha−1 yr−1 increased extractable P 1.0 kg for every 4.2 kg added P if only topsoil was considered, for every 3.2 kg added P if corn grain P removal was deducted, and for every 2.8 kg added P if subsoil increases were included but corn P uptake excluded, and 2.1 kg added P with subsoil P included and corn P removal deducted. Without manure, 132 kg P ha−1 yr−1 increased Mehlich-3 extractable P by 1.0 kg for every 8.1 kg P added, or 5.3 kg P added if corn P removal was deducted from added fertilizer P. At the low rate of 44 kg P ha−1 with manure P, Mehlich-3 levels increased by 1.0 kg P for every 5.2 kg added fertilizer P. Extractable P remained constant when inorganic fertilizer P was added without manure, probably because crop removals equalled fertilizer additions. Mehlich-3 extractable K increased in both top soil and subsoil at rates of 141 and 332 kg ha−1 yr−1 inorganic K except for the 141 K rate in the final four years when no manure was applied. When both soil depths were included and summed over all years, values of added K to increase extractable K by 1.0 kg ranged from 4.2 to 5.5 kg, regardless of source or rate of added K. To increase soil test P, manure combined with high P rates was more effective per unit added P than low P rates or added P without manure. Either form or rate of added K was equivalent in increasing extractable K. Key words: Long-term fertilization, continuous corn, organic manure P, inorganic P, Mehlich-3 extractable P, Mehlich-3 extractable K
26
Stumborg, C., e J. J. Schoenau. "Evaluating phosphorus loading from repeated manure applications to two Saskatchewansoils". Canadian Journal of Soil Science 88, n. 3 (2 maggio 2008): 377–87. http://dx.doi.org/10.4141/s06-048.
Abstract (sommario):
An understanding of the impact of repeated manure additions on soil phosphorus (P) is needed to determine appropriate manure application rates for prairie soils and manure sources. The objective of this study was to assess the loading of manure-derived phosphorus using P budgets and soil P measurement techniques applied to two Saskatchewan soils with known histories of manure application. Liquid hog manure (LHM) and solid cattle manure (SCM) treatments were applied annually over 8 yr to Black Chernozemic soils (Dixon site), and LHM was applied to Dark Brown Chernozemic soils (Plenty site) over 6 yr. Soil samples were collected in the spring of 2003 and 2004 and analyzed for labile P (Modified Kelowna extractable, Olsen extractable, water extractable, and Plant Root Simulator exchange resin methods) and total P. The P budgets were in good agreement with the observed patterns in labile soil P at the two sites. The annual application of LHM (37000 L ha-1 yr-1) at agronomic nitrogen (N) rates with no additional P fertilizer (Dixon only) did not significantly elevate soil labile P compared with the unfertilized controls at both Dixon and Plenty. The annual application of SCM (7.6 Mg ha-1 yr-1) at agronomic N rates did not significantly elevate soil labile P compared with the unfertilized control at Dixon; whereas of SCM at higher rates (15.2 Mg ha-1 yr-1 and 30.4 Mg ha-1 yr-1) showed some elevation in labile soil P. Measures of labile P were sensitive to P surpluses or deficits predicted by P balances, and all methods of measuring labile soil P were strongly correlated with one another at both sites (r ≥ 0.803 at P ≤ 0.01). Key words: Manure, cattle manure, nitrogen, phosphorus, soil test phosphorus
27
EVANS Jr., A., e R. C. SORENSEN. "EFFECT OF IONIC STRENGTH AND SOLUTION pH ON P EXTRACTABILITY AND LEACHING IN COARSE-TEXTURED SOILS". Canadian Journal of Soil Science 65, n. 1 (1 febbraio 1985): 101–8. http://dx.doi.org/10.4141/cjss85-011.
Abstract (sommario):
A laboratory study was conducted using columns of Valentine loamy sand to determine the effect of ionic strength (I) and solution pH of a leaching solution on P distribution and extractability with depth. Solutions of KCl at concentrations of 1.0, 10−2, 10−4 and 10−6 mol∙L−1 with a pH of either 4.0, 6.0, or 8.0 were added to the column after the application of 0.3 g diammonium phosphate to the surface of each column. Approximately two pore volumes, 500 mL of solution, were added to the columns, after which they were sectioned and the amount of Bray extractable P in each section was measured. Increasing I resulted in an increase in the total amount of Bray extractable P per column while extractable P increased with column depth for decreasing I. The pH of the leaching solution did not influence the total amount of Bray extractable P per column, but appeared to influence P distribution for the I = 10−2 treatment. Dissolved organic carbon in the leachate was found to increase with decreasing I. Changes in the distribution of extractable P with depth were attributed to increased competition for P adsorption sites by various organic molecules, which were released into the bulk solution when the organic matter coatings underwent a transition from the spherocolloid to the linear flexible molecule configuration. Key words: Ionic strength, P movement, organic matter coatings, spherocolloid, anion competition
28
Simard, R. R., S. Beauchemin e M. R. Laverdière. "Limed sewage sludge effects on nutrient status and metal fractions in acidic soils". Canadian Journal of Soil Science 79, n. 1 (1 febbraio 1999): 173–82. http://dx.doi.org/10.4141/s98-021.
Abstract (sommario):
The potential impacts of limed sludge on nutrient and heavy metal bioavailability must be studied for their safe use on acidic soils. The objective of this study was to assess the impact of limed sludges on six acidic soils from eastern Canada. CaCO3 and raw sewage sludges (RSS) stabilized with either CaO (CaO + S) or cement kiln dust (CKD + S) were added to soils in amount necessary to reach pH 6.5 and the mixtures were then incubated for 64 d. CaO + S treatments were the most efficient to neutralize soil acidity. After 10 d of incubation, the Sr-citrate extractable P was significantly increased by the CaO + S treatment in low P sorption soils. The extractable K, Zn and Cu contents were also slightly increased by CaO + S compared to CaCO3 whereas CKD + S resulted in an excessive soil exchangeable K content. After 64 d, labile Al content was decreased by all liming amendments. RSS and CaO + S tended to increase labile Cu and Mn contents. The RSS increased NaOH-extractable Cu but the treatments had no significant effects on the labile and stable forms of heavy metals. A combination of CaO + CKD to stabilize sewage sludge would be more suitable to provide appropriate levels of P and K without resulting in large increases in extractable heavy metal contents. Key words: pH, extractable P and K, cement kiln dust, Al and Mn toxicity, Cu fractions, water-soluble metals
29
Bowen, P. A., B. J. Zebarth e P. M. A. Toivonen. "Dynamics of nitrogen and dry-matter partitioning and accumulation in broccoli (Brassica oleracea var. italica) in relation to extractable soil inorganic nitrogen". Canadian Journal of Plant Science 79, n. 2 (1 aprile 1999): 277–86. http://dx.doi.org/10.4141/p98-056.
Abstract (sommario):
The effects of six rates of N fertilization (0, 125, 250, 375, 500 and 625 kg N ha−1) on the dynamics of N utilization relative to extractable inorganic N in the soil profile were determined for broccoli in three growing seasons. The amount of pre-existing extractable inorganic N in the soil was lowest for the spring planting, followed by the early-summer then late-summer plantings. During the first 2 wk after transplanting, plant dry-matter (DM) and N accumulation rates were low, and because of the mineralization of soil organic N the extractable soil inorganic N increased over that added as fertilizer, especially in the top 30 cm. From 4 wk after transplanting until harvest, DM and N accumulation in the plants was rapid and corresponded to a rapid depletion of extractable inorganic N from the soil. At high N-fertilization rates, leaf and stem DM and N accumulations at harvest were similar among the three plantings. However, the rates of accumulation in the two summer plantings were higher before and lower after inflorescence initiation than those in the spring planting. Under N treatments of 0 and 125 kg ha−1, total N in leaf tissue and the rate of leaf DM accumulation decreased while inflorescences developed. There was little extractable inorganic soil-N during inflorescence development in plots receiving no N fertilizer, yet inflorescence dry weights and N contents were ≥50 and ≥30%, respectively, of the maxima achieved with N fertilization. These results indicate that substantial N is translocated from leaves to support broccoli inflorescence growth under conditions of low soil-N availability. Key words: N translocation, N fertilizer
30
Meyer, Wietse L., e Paul A. Arp. "Exchangeable cations and cation exchange capacity of forest soil samples: Effects of drying, storage, and horizon". Canadian Journal of Soil Science 74, n. 4 (1 novembre 1994): 421–29. http://dx.doi.org/10.4141/cjss94-055.
Abstract (sommario):
Concentrations of Ca, Mg, K, Na, Al, Fe, Mn, and Si extractable with 1 N ammonium chloride (NH4Cl, pH 4.5) and 1 N ammonium acetate (NH4OAc, pH 4.5) were determined for forest soil samples as follows: (1) before drying, and (2) at several time intervals after air-drying (1, 5, 11 and 14 wk). Values for CEC were obtained for the same samples by determining (1) the sum of cations (Al3+, Ca2+, Mg2+, K+, Na+, Fe3+, and Mn2+) in the extracts [denoted [Formula: see text] and [Formula: see text]], and (2) the amount of ammonium retained by the soil samples against water washing [denoted CEC(NH4OAc) and CEC (NH4Cl)]. The soils used in this investigation were taken from four New Brunswick upland forest sites (two sugar maple sites, one mixed wood site, and one spruce site). It was round that (1) extractable Mg, K, Na, and Mn levels were generally not affected by drying, storing, and type of extradant; (2) extractable Al and Fe levels increased immediately after drying; (3) NH4OAc-extracted Al, Fe, and Si exceeded NH4Cl-extracted Al, Fe, and Si; (4) extracted Al and Fe levels tended to drop after 11 wk of storage; (5) small drying effects were also noticed for NH4Cl-extracted Ca; (6) CEC(NH4OAc) and CEC(NH4Cl) values decreased with increasing time of storage; this effect was noticed most for soil samples with high levels of organic matter (Ah, Ahe, Bm, Bf, and Bfh), and was noticed least for sod samples taken from leached horizons (Ae) and subsoil horizons (BC and C); (7) in some cases, storage time increased CEC(NH4OAc) in subsoils; (8) values for [Formula: see text] remained fairly independent or increased slightly with storage time and were closely related with CEC(NH4Cl) values obtained with non-dried samples; (9) values for [Formula: see text] did not relate well with CEC(NH4OAc) and CEC(NH4Cl). Differences for extractable Al were likely due to Al complexation by acetate ions. Drying effects on extractable Al and Fe (and possibly Ca) were likely due to drying-induced fragmentation of soil organic matter. Drying and storage effects on CEC(NH4OAc) and CEC(NH4Cl) were likely due to (1) water-washing and related loss of organic matter, and (2) sensitivity of subsoil minerals to air exposure. Apparent drying and storage effects on CEC were most noted with [Formula: see text] and were least noted with [Formula: see text]. Key words: Cation exchange capacity, ion exchange, drying, storage, ammonium acetate, ammonium chloride extractions
31
LIANG, J., J. W. B. STEWART e R. E. KARAMANOS. "DISTRIBUTION OF ZINC FRACTIONS IN PRAIRIE SOILS". Canadian Journal of Soil Science 70, n. 3 (1 agosto 1990): 335–42. http://dx.doi.org/10.4141/cjss90-034.
Abstract (sommario):
The distribution of Zn in soil fractions was determined for 27 representative prairie soils from Saskatchewan. Total Zn in the 27 soils under study ranged from 19.0 to 106.6 μg g−1 with an average of 62.0 μg g−1. A sequential fractionation showed that 0.2–2.4% of total Zn was exchangeable, 0.4–8.1% was Pb-displaceable, 0.4–4.3% was acid soluble, 1.6–9.7% was associated with Mn oxides, 0.6–4.4% was associated with organic matter and 0.9–5.1% was associated with Fe + Al oxides. Most of the total Zn was present in residual form (66.9–91.0%). Amounts of Zn in exchangeable and Pb-displaceable fractions varied inversely with soil pH and extractable P. DTPA-extractable Zn was correlated with Zn in most of the fractions, except Fe oxide-Zn, residual-Zn and total Zn. This result indicates that DTPA extractable-Zn contains Zn from Mn oxides and organic matter associations in addition to the exchangeable and adsorbed forms. The amount of total Zn was correlated with clay content and cation exchange capacity thus reflecting differences in parent materials. Key words: Soil Zn, Zn fractions, Prairie soils, pH, clay content
32
Kashem, Md Abul, Olalekan Oluwole Akinremi e Geza Joseph Racz. "Extractable phosphorus in alkaline soils amended with high rates of organic and inorganic phosphorus". Canadian Journal of Soil Science 84, n. 4 (1 novembre 2004): 459–67. http://dx.doi.org/10.4141/s03-085.
Abstract (sommario):
Information on the extractable P in soils treated with different organic amendments and how it changes with time is important to a sound management of manure addition to agriculture soils. This laboratory study investigated the impact of adding municipal biosolids, hog and cattle manures and monoammonium phosphate (MAP) on extractable P in soils. Phosphorus was added at rates of 0, 110, 220, 440 and 880 mg P kg-1 for the Osborne soil (Gleysolic Humic Vertisol), and 0, 123, 307 and 614 mg P kg-1 for the Lakeland soil (Gleyed Rego Black Chernozem) in the form of biosolids, hog manure, cattle manure and MAP. The soils were incubated at field capacity for 1, 4, 16 and 32 wk after which they were extracted using H2O, NH4Cl, NaHCO3 (Olsen P), and the Kelowna and Mehlich-3 extracts. Regardless of extractant and soil, extractable P was small 1 wk after adding biosolids (17-93 mg kg-1 as Olsen P) and large with MAP (59-672 mg kg-1 as Olsen P) while hog and cattle manures were intermediate between biosolids and MAP (20-461 mg kg-1 as Olsen P). In biosolids-amended soils, extractable P increased slightly with increasing incubation time indicating net P mineralization. With MAP, extractable P declined from 672 mg kg-1 after 1 wk to 157 mg kg-1 after 16 wk of incubation at the highest P application rate in the Osborne soil. In the Lakeland soil, the decrease in extractable P with MAP addition was small (from 398 to 332 mg kg-1) and was similar to the changes with cattle manure P with incubation time. Extractable P with cattle manure in the Osborne soil and with hog manure in the Lakeland soil did not change with incubation time. In both soils, extraction efficiency was in the order of H2O < NH4Cl < NaHCO3 < Kelowna < Mehlich-3. Across P application rates, the efficiency of added P as measured by NaHCO3 increased only with biosol ids from 12% after 1 wk to 21% after 32 wk of incubation, while it decreased in the same period from 55 to 44% with hog manure, from 34 to 32% with cattle manure and from 74 to 17% with MAP in the Osborne soil. Soil samples taken 4 wk following addition o f hog and cattle manures should reflect plant-available P, while soil samples taken within the same period following the application of biosolids are likely to underestimate plant-available P. Key words: Extractable phosphorus, organic amendments, soils, single extraction, incubation
33
PASCALE, G. DI, e A. VIOLANTE. "INFLUENCE OF PHOSPHATE IONS ON THE EXTRACTION OF ALUMINUM BY 8-HYDROXYQUINOLINE FROM OH-AL SUSPENSIONS". Canadian Journal of Soil Science 66, n. 4 (1 novembre 1986): 573–79. http://dx.doi.org/10.4141/cjss86-057.
Abstract (sommario):
Aluminum was extracted from OH-Al-suspensions ([Al3+] = 6.4 × 10−4 mol L−1; OH/Al molar ratio = 1.0, 1.5, 2.2) aged 5 and 18 mo by 8-hydroxyquinoline into four different species: readily extractable (Alre), moderately ex tractable (Alme), slowly extractable (ALse) and nonextractable (Alne) aluminum. In all the systems, the percentages of Alre were the highest of the ultrafiltered hydrolytic products of Al, ranging from 68.1 to 21.1%, whereas the percentages of Alme and Alse were [Formula: see text]. The higher the OH/Al molar ratio and the longer the aging period of OH-Al-suspensions, the lower the percentages of Alre, Alme and Alse, and the higher the percentages of Alne (ranging from 13.3 to 71.1%). With addition of phosphate ions, increasing the P/Al molar ratio from 0.05 to 0.5 decreased Alre and increased Alne. Finally, it was ascertained that the ultrafiltered aluminum was not completely extracted by 8-hydroxyquinoline after 3 h. More aluminum was extracted from 3 to 48 h from the suspensions containing phosphate ions than from those without phosphate. Key words: Aluminum hydrolytic products, phosphate, aluminum extraction, 8-hydroxyquinoline
34
Ige, D. V., O. O. Akinremi, D. Flaten e M. A. Kashem. "Comparison of soil test phosphorus methods in neutral to calcareous Manitoba soils". Canadian Journal of Soil Science 86, n. 4 (1 agosto 2006): 691–99. http://dx.doi.org/10.4141/s05-045.
Abstract (sommario):
Increasing concern for the amount of P entering lakes in Manitoba may lead to regulation of P concentration in agricultural soils. A possible means for this regulation is the use of soil test P. This may require a means of comparing soil test P analyses as various laboratories in Manitoba employ different methods of soil test P determination. Thus, the objectives of this study were to (i) compare the methods of P determination in Manitoba soils, and (ii) develop equations for converting different soil test P methods from one to another. One hundred and fifteen archived surface soil samples representing major soils of Manitoba were used for the study. Soil test P was determined in these soils using the original Kelowna (K1) method and the two modified Kelowna methods (K2 and K3). Mehlich-3, Olsen- and water extractable-P were also determined for all soils. The results were analyzed statistically and were related using a simple regression analysis model. The amount of P extracted by the different extracting agents varied widely. Mehlich-3 extracted the largest amount of P (a range of 5.4–200 mg kg-1) while water extracted the smallest amount (a range of 0.2–70 mg kg-1). The P extracted by the Olsen and the three Kelowna methods were intermediate between Mehlich-3 and water-P. Our results also showed that the three Kelowna methods were not significantly different from one another. The Olsen method compared well with those of the modified Kelowna methods, but extracted less P than the original Kelowna and Mehlich-3 methods. Overall, the different agronomic soil test P methods were well correlated to each other with correlation coefficients (r) ranging between 0.95 and 0.98. However, the correlations between these soil test methods and water extractable P was not as high. Water extractable P and the agronomic soil test P methods were better related by a non-linear relationship than by a linear relationship. The coefficient of determination (R2) for all the regression equations relating the different agronomic soil test P methods ranged from 0.91 to 0.97. As such, the equations generated in this study can be used to convert the result from one soil test P method to another. Key words: Kelowna extractable phosphorus, Mehlich-3 extractable phosphorus, Olsen extractable phosphorus, water extractable phosphorus
35
SOON, Y. K., e S. ABBOUD. "TRACE ELEMENTS IN AGRICULTURAL SOILS OF NORTHWESTERN ALBERTA". Canadian Journal of Soil Science 70, n. 3 (1 agosto 1990): 277–88. http://dx.doi.org/10.4141/cjss90-029.
Abstract (sommario):
Fifty-two surface soils and 11 subsoils collected from agricultural soils of the Peace River region of northwestern Alberta were analyzed for total and extractable contents of Cd, Cr, Cu, Mn, Ni, Pb and Zn. The purpose of this survey was to build up a data base on trace element contents of agricultural and environmental concerns for soils of this region. Extractable amounts were determined by DTPA-ammonium bicarbonate, 0.05 M EDTA, 0.1 M HCl and saturation extractions. Total Cd, Cr, Cu, Mn and Pb concentrations were similar to average values for "world" soils; Ni was less than and Zn greater than "world" average. Total Cr was higher and total Pb lower than average values reported for Canadian soils. Total Cd, Cu, Ni, Pb and Zn were similar in surface and subsurface soils. Extractable Cd, Mn, Ni and Zn tended to be greater in surface soils compared to subsoils; Cu and Pb were higher in the clay-enriched subsoils. Among the surface soils, soils with higher amounts of organic matter contained greater amounts of total and extractable metals with few exceptions. Clay content was also closely correlated with the distribution and content of Cu, Pb and Cr. Few, if any, of the soils would be expected to be deficient in Cu, Mn or Zn for the production of crops. Key words: Cadmium, copper, chromium, manganese, nickel, lead, zinc
36
Nesdoly, R. G., e K. C. J. Vanrees. "Redistribution of extractable nutrients following disc trenching on Luvisols and Brunisols in Saskatchewan". Canadian Journal of Soil Science 78, n. 2 (1 maggio 1998): 367–76. http://dx.doi.org/10.4141/s97-057.
Abstract (sommario):
Disc trenching is an important silvicultural management tool for creating microsites to ensure the survival and growth of newly planted seedlings. Mounded microsites are thought to be a source of nutrients for seedling roots; however, little is known concerning how nutrients are redistributed in the soil after disc trenching. The objective of this study, therefore, was to determine the redistribution of soil horizons and selected soil chemical properties following Delta disc trenching. Three sites were selected on both Luvisol and Brunisol soils in northern Saskatchewan. Soil profiles were excavated and samples collected from 15 × 5 cm grids to a 1-m depth. Samples were analyzed for pH and extractable nitrate (NO3), ammonium (NH4), phosphorus (P), potassium (K) and sulfur (S). Disc trenching concentrated extractable N, P and S in the berm microsite compared to the trench microsites. The redistribution of extractable NO3, NH4 and P in the berms compared to the trench microsites was 20 times greater for Luvisol sites compared to the Brunisol sites, while extractable K and S were similar between both microsites for each soil. Seedlings planted on these mounded microsites therefore should have a large pool of nutrients for plant growth; however, further work is needed to determine patterns of nutrient uptake by seedlings in relation to mounded and trench microsites. Key words: Delta disc trenching, boreal forest, Luvisols, Brunisols, nutrients
37
Prescott, C. E., M. A. McDonald e G. F. Weetman. "Availability of N and P in the forest floors of adjacent stands of western red cedar–western hemlock and western hemlock–amabilis fir on northern Vancouver Island". Canadian Journal of Forest Research 23, n. 4 (1 aprile 1993): 605–10. http://dx.doi.org/10.1139/x93-080.
Abstract (sommario):
Availability of N and P was compared in the forest floors of old-growth forests of western red cedar (Thujaplicata Donn)and western hemlock (Tsugaheterophylla (Raf.) Sarg.) (CH forests), and second-growth forests of western hemlock and amabilis fir (Abiesamabilis (Dougl.) Forbes) (HA forests) of windthrow origin. Five samples of each forest floor layer (litter, fermentation (woody and nonwoody), and humus (woody and nonwoody)) were collected from three forests of each type (CH and HA). All layers of CH forest floors had smaller concentrations of total and extractable N and mineralized less N during 40-day aerobic incubations in the laboratory. Total and extractable P was lower in the litter layer of CH forest floors. Seedlings of western red cedar, Sitka spruce (Piceasitchensis (Bong.) Carr.), western hemlock, and amabilis fir grown from seed in forest floor material from CH forests grew more slowly and took up less N and P than did seedlings grown in HA forest floor material. The low supply of N and P in CH forest floors may contribute to the nutrient supply problems encountered by regenerating trees on cutovers of this forest type.
38
Zeng, L., R. L. Johnson, X. Li e J. Liu. "Phosphorus removal from aqueous solutions by sorption on two volcanic soils". Canadian Journal of Soil Science 83, n. 5 (1 novembre 2003): 547–56. http://dx.doi.org/10.4141/s03-006.
Abstract (sommario):
The use of low-cost materials for P removal is of interest for developing cost-effective techniques for preventing P pollution. This paper reports a study on phosphate removal from aqueous solutions by sorption on two volcanic soils. The raw and HCl-treated soils were characterized with respect to oxalate-extractable and dithionite-extractable Al and Fe contents, surface area, and P sorption capacities. The phosphate sorption isotherms, kinetics, pH effects, and desorbability were evaluated in batch tests. The measured isotherm data were well fitted by the Freundlich and Temkin models. Phosphate sorption on these soils was relatively fast and the kinetics could be satisfactorily described by the simple Elovich and power function equations. The two soils had maximum phosphate sorption capacities of approximately 0.85 and 1.35 mg g-1 gram of soil at pH 6.0–6.5. The pH had different effects on phosphate sorption on these soils, likely due to either calcium phosphate precipitation or surface repulsion of the negatively charged phosphate species at a higher pH. Column flow-through tests using both synthetic phosphate solution and liquid swine manure confirmed the phosphate removal ability of the volcanic soils. It was concluded that volcanic soils could be potential low-cost materials for controlling P pollution from agricultural sources. Key words: Phosphate removal, volcanic soil, sorption, isotherm, kinetics, desorption
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Pizzeghello, Diego, Livio Bellin, Serenella Nardi, Ornella Francioso, Andrea Squartini e Giuseppe Concheri. "Wood-Based Compost Affects Soil Fertility and the Content of Available Forms of Nutrients in Vineyard and Field-Scale Agroecosystems". Agronomy 11, n. 3 (10 marzo 2021): 518. http://dx.doi.org/10.3390/agronomy11030518.
Abstract (sommario):
To counteract the loss of organic matter of agricultural soils, the use of compost from green and woody residues is a promising strategy. In this study, an organic farm (NE Italy) was investigated to determine the effect of management practices on physical and chemical soil properties. The organic system received three years ago a single high dose (60 t ha−1) of a wood-based compost (WBC), and it was compared with a conventional farm that annually managed mineral plus manure fertilization. In both systems, soil samples from a vineyard and field-scale rotation were collected, together with soil samples from an area not cultivated and not treated neither with compost nor with fertilizers or manure (untreated = control). Soil samples were characterized for soil fertility parameters, extractable fractions of macro- and micronutrients with DTPA and Mehlich3, and their total content. WBC was physically, chemically, and biologically characterized. The results showed that WBC fulfilled the requirements prescribed by Italian legislation, and the absence of phytotoxicity and conversely a stimulating activity towards root development was evidenced. From the DNA metabarcoding of the bacterial community, WBC revealed several peculiarities, including the dominance of taxa such as the order Acidimicrobiales, the families Anerolineaceae, Cytophagaceae, Caldimicrobiacese, Saprospiraceae and the archaeon Candidatus Nitrososphaera. Concerning the fertility of soils, the addition of WBC in both the vineyard and field-scale considerably affected some important soil parameters compared to those of conventional fertilization and untreated soil. Among these, WBC strongly increased the organic C content and the amount of the available P. In addition, the concentrations of macro- and micronutrients extractable by DTPA were generally higher with WBC than conventional fertilization. On the contrary, Mehlich3 extractable metals and total metals content were not affected by fertilization. The principal component analysis indicated that organic C, macronutrients (CaDTPA, KDTPA, and POlsen), as well as micronutrients (BDTPA, FeDTPA, and MoDTPA) are principal factors that properly separated conventional fertilization from organic fertilization. Beside this, within the same management, cases by agroecosystem were also well revealed by cluster analysis. In essence, in the short-term, the organic system led to a significant improvement in organic C and plant-available nutrients over the conventional system.
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Campbell, L. G., e K. L. Klotz. "Characterizing sugarbeet varieties for postharvest storage losses is complicated by environmental effects and genotype × environment interactions". Canadian Journal of Plant Science 87, n. 1 (1 gennaio 2007): 121–27. http://dx.doi.org/10.4141/p06-085.
Abstract (sommario):
Each year millions of tons of sugarbeet (Beta vulgaris L.) roots are stored in large exposed piles prior to processing. During postharvest storage, respiration and invert sugar formation consume sucrose and even a small reduction in these losses would have substantial economic impact. This study investigated the relative importance of hybrid, environment, and hybrid × environment interactions and examined their implications in characterizing hybrids for sucrose loss during storage or developing hybrids with improved storage properties. Glucose, fructose, and extractable sucrose concentrations and respiration rate were measured 30 and 120 d after harvest (DAH) on five hybrids produced in six environments. Environment effects were significant on both dates for all traits except fructose 30 DAH. Significant hybrid × environment interactions were observed for respiration rate 30 and 120 DAH, for extractable sucrose 120 DAH, and for glucose concentration 30 DAH. The only trait with a significant hybrid main effect was extractable sucrose 30 DAH. For the 90 d between measurements, extractable sucrose losses for individual hybrid-environment combinations ranged from 1 to 63% of the sucrose available 30 DAH. It appeared that large environmental impacts and hybrid × environment interactions, compared to the relatively small hybrid influences, would complicate selecting parental lines with all or most of the storage traits desired. Furthermore, a comprehensive evaluation of commercial hybrids or breeding lines for storage traits would require considerable resources. Efforts to understand the impact of production practices and growing season environment on storage properties would probably be more productive than attempting to produce commercial hybrids with improved storage characteristics. Key words: Beta vulgaris L., respiration, glucose, fructose, extractable sucrose
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STRONG, W. L., e G. H. LA ROI. "USE OF SOIL HORIZONS AS ECOLOGICAL SAMPLING UNITS". Canadian Journal of Soil Science 68, n. 1 (1 febbraio 1988): 151–55. http://dx.doi.org/10.4141/cjss88-014.
Abstract (sommario):
Extractable nutrients and physical properties of Eutric Brunisols from pine and aspen stands were evaluated for their relationship to soil horizons classified according to morphological criteria. The results indicate strong horizon-nutrient associations, suggesting that soil horizons are appropriate sampling units for ecological studies concerned with below-ground nutrient and edaphic conditions. Key words: Nutrients, principal components analysis, soil horizon
42
Dwyer, L. M., M. Tollenaar e L. Houwing. "A nondestructive method to monitor leaf greenness in corn". Canadian Journal of Plant Science 71, n. 2 (1 aprile 1991): 505–9. http://dx.doi.org/10.4141/cjps91-070.
Abstract (sommario):
A portable chlorophyll meter was calibrated with extractable chlorophyll measurements from six corn (Zea mays L.) hybrids, and the utility of the meter in identifying differences in leaf greenness was assessed in growth-cabinet and field studies. A single linear regression described the relationship between meter readings and extractable chlorophyll concentration for leaves of all hybrids at a range of growth stages (r2 = 0.83). Meter measurements resolved differences in chlorophyll concentration of two additional test hybrids resulting from different temperature regimes in the growth-cabinet, and from different leaf positions and stages of development in the field (P < 0.01). Considerable replication of meter readings was found necessary to resolve treatment differences in chlorophyll concentration. Caution is advised in using the calibration at very low chlorophyll concentrations such as those occurring as the plant nears senescence. Key words: SPAD 501, chlorophyll, leaf senescence, linear regression
43
Boyle, C. David, e Bradley R. Kropp. "Development and comparison of methods for measuring growth of filamentous fungi on wood". Canadian Journal of Microbiology 38, n. 10 (1 ottobre 1992): 1053–60. http://dx.doi.org/10.1139/m92-173.
Abstract (sommario):
Measures of fungal growth with potential for use on wood-chip media were developed. These included (i) visual inspection, (ii) substrate dry weight loss, (iii) rate of fluorescein diacetate hydrolysis, (iv) extractable protein content, and (v) chitin content of the colonized substrate. The responses of the various assays to different growing conditions were assessed by using them on measured weights of mycelium, collected at intervals from liquid media with various composition. Growth of various species on either nutrient supplemented or unsupplemented wood chips was then measured. Each assay measured a different aspect of growth. The relationship between these changed in a distinctive way for each species during growth. Chitin gave the best measure of biomass, whereas fluorescein diacetate hydrolysis was a measure of growth-related metabolic activity. The protein and substrate dry weight loss data gave information about fungal protein and carbohydrate metabolism of the species, respectively. Addition of nutrient supplement to the wood increased both biomass and growth-related metabolic activity. It also increased the amount of wood used to produce a given amount of biomass by about 500% with some species. Some species showed a strong capacity to lower their cellular protein concentration during growth, which is probably of advantage for growth on a low-N substrate such as wood. Used together, the assays gave insight into different strategies fungi use to grow on wood. Key words: fungi, growth, chitin, fluorescein diacetate.
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Nakagaito, Antonio Norio, Yusuke Katsumoto e Hitoshi Takagi. "Extraction of cellulose nanofiber from parenchyma cells of agricultural residues". Modern Physics Letters B 33, n. 14n15 (28 maggio 2019): 1940012. http://dx.doi.org/10.1142/s0217984919400128.
Abstract (sommario):
Cellulose nanofiber is an environmentally friendly reinforcing phase extractable from plants, with potential application in composites. Due to the cell wall structure differences, plant parenchyma cells might be easier to nanofibrillate than sclerenchyma cells of wood pulp fibers, resulting in lower extraction costs. This study assessed the extraction of nanofibers from residues like corn husk, banana peel, cabbage leaf, and taro leaf using a kitchen blender. Fibrillation was evaluated based on the strength of paper-like sheets produced from the nanofibers. Corn husk was nanofibrillated by the shortest blending time among the sources considered, and delivered the highest sheet strength. The blending time needed was significantly shorter than that needed to fibrillate hardwood pulp fibers.
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GIROUX, M., e T. SEN TRAN. "EVALUATION DU PHOSPHORE ASSIMILABLE DES SOLS ACIDES AVEC DIFFERENTES METHODES D’EXTRACTION EN RELATION AVEC LE RENDEMENT DE L’AVOINE ET LES PROPRIETES DU SOL". Canadian Journal of Soil Science 65, n. 1 (1 febbraio 1985): 47–60. http://dx.doi.org/10.4141/cjss85-006.
Abstract (sommario):
The objective of this study was to evaluate different available P extracting methods in relation with soil properties, oat yield and plant P uptake. Six chemical extractants (Bray-1, Bray-2, new Mehlich, North Carolina DA-4, DA-10, and Olsen) and two anion exchange resins (F− and HCO3−) were compared on 42 acid soils. The DA-4, DA-10, new Mehlich, and HCO3− resin methods showed the best correlation with oat yield and plant P uptake. The Bray-1, Bray-2 methods were significantly less correlated than the other methods. The HCO3− resin was better than F− resin to predict plant P uptake and yield. Available P levels as determined by these eight methods were classified poor, medium and rich by the Cate and Nelson procedure. Oxalate extractable Al, pH (NaF), pH (H2O), exchangeable (Ca + Mg), forms of P, maximum P fixation capacity and soil texture have great influence on the plant P uptake. Soil organic matter content and oxalate-extractable Fe had significantly less important an effect. The Bray-1 and Bray-2 methods were the most affected by soil properties especially oxalate-extractable Al. The P-HCl/P-DAF ratio proposed by Mehlich to identify forms of soil P indicated that seven soils contain predominantly Ca-P and 21 soils with predominantly Al-P and Fe-P. This ratio was related with oxalate extractable Al (r = − 0.32*), pH NaF (r = − 0.59**), pH H2O (r = 0.52**) and exchangeable Ca + Mg (r = 0.55**). The maximum P fixation capacity (M) ranged from 150 to 4200 μg P/g soil and was closely related with oxalate-extractable Al (r = 0.81**), pH NaF (r = 0.74**), pH H2O (r = − 0.36*) and Mehlich ratio (r = − 0.33*). The maximum P buffering capacity (Mb) of soils was also measured and showed the best correlation with oxalate-extractable Al (r = 0.84**) and pH NaF (r = 0.53**). Key words: Soil testing, available P, anion exchange resins, P fixation, oxalate-Al, forms of P
46
Arrais, A., E. Diana e E. Boccaleri. "A study on the carbon soot derived from the wood combustion and on the relative alkali-extractable fraction". Journal of Materials Science 41, n. 18 (settembre 2006): 6035–45. http://dx.doi.org/10.1007/s10853-006-0511-z.
47
SIMARD, R. R., J. ZIZKA e C. R. DE KIMPE. "THE KINETICS OF NONEXCHANGEABLE POTASSIUM AND MAGNESIUM RELEASE FROM QUEBEC SOILS". Canadian Journal of Soil Science 69, n. 3 (1 agosto 1989): 663–75. http://dx.doi.org/10.4141/cjss89-065.
Abstract (sommario):
Ligands such as complexing organic acids play a significant role in the dynamics of release of plant nutrients in soils. The objective of this work was to study the dynamics of slowly exchangeable K and Mg release from 12 Quebec soils by ten successive extractions with 5 × 10−4 M citric acid, over a period of 1800 h, and by a single extraction with boiling 1.0 M HNO3. All soils were characterized by a mixed clay mineralogical composition with swelling minerals as major components. The kinetics of slowly exchangeable K and Mg cumulative release were described using two forms of the Elovich, the parabolic diffusion, power function, and first and zero order equations. Comparisons of r and SE values showed that the extended form of the Elovich equation best fitted K and Mg release to citric acid. The amount and rate of K release by the citric acid procedure were highly correlated to the amounts of slowly exchangeable HNO3-extractable and rapidly exchangeable NH4OAc-extractable K and to the coarse clay content of the soils. The amount of Mg released to citric acid was proportional to the unbuffered cation exchange capacity of the soils. The results indicated that the citric acid procedure was a time saving alternative to the study of the kinetics of slowly exchangeable K and Mg release from soils. Key words: Nonexchangeable K, citric acid, nonexchangeable Mg, podzolic soils, kinetics
48
Liang, J., J. W. B. Stewart e R. E. Karamanos. "Distribution and plant availability of soil copper fractions in Saskatchewan". Canadian Journal of Soil Science 71, n. 1 (1 febbraio 1991): 89–99. http://dx.doi.org/10.4141/cjss91-008.
Abstract (sommario):
Growth chamber and laboratory studies were conducted to investigate the distribution and plant availability of copper (Cu) fractions in Saskatchewan soils. These studies included an examination of the distribution of Cu fractions in 27 soils and an evaluation of plant availability of native and added Cu fractions in beans (Phaseolus vulgaris L.) grown in seven soils. The soils in these experiments were selected to give a wide variation in physical and chemical properties. Total Cu content of the 27 soils ranged from 6.5 to 39.0 μg g−1 with an average of 21.0 μg g−1. A seven-step sequential fractionation showed that most of the total Cu (49.0–78.0%) was present in the residual fraction (Res-). The percentages of soil Cu in the exchangeable (Ex-), Pb-displaceable (Pb-), acid soluble (Aci-), Mn oxide bound (MnO-), organically associated (OM-) and Fe, Al oxide bound (FeO-) fractions averaged 2.2, 1.5, 2.0, 4.8, 7.9 and 11.1%, respectively. Amounts of Cu in MnO-, FeO-, Res- fractions and total Cu were interdependent and varied directly with DTP A- extractable Cu and clay content. The growth chamber experiment showed that the most of the applied Cu was accumulated in MnO-, OM-, FeO-, and Res- fractions. Therefore, sesquioxides and organic matter are the major components responsible for the adsorption of added Cu. The concentration of Cu and its uptake into navy beans were positively correlated with DTPA-extractable Cu, MnO-Cu, FeO-Cu and total Cu, which in turn were correlated with clay content. Plant Cu concentration and uptake can be predicted by an equation which includes DTPA-extractable Cu and clay content. These results showed that DTPA-extractable Cu is a good predictor of Cu availability in prairie soils. Key words: Cu fractions, distribution, availability, DTPA-extractable Cu, clay content, navy beans
49
Maehara, Noritoshi, Junichi Kikuchi e Kazuyoshi Futai. "Mycorrhizae of Japanese black pine (Pinus thunbergii): protection of seedlings from acid mist and effect of acid mist on mycorrhiza formation". Canadian Journal of Botany 71, n. 12 (1 dicembre 1993): 1562–67. http://dx.doi.org/10.1139/b93-190.
Abstract (sommario):
To determine the effects of acid precipitation on Japanese black pine (Pinus thunbergii Parl.) with and without mycorrhizae (Pisolithus tinctorius (Pers.) Coker et Couch), 1-year-old seedlings were exposed to simulated acid mist, pH 3.0, for 10 min per day twice a week for 3 or 4 months. Simulated acid mist adversely affected the transpiration rate and lowered the extractable phosphorus content of seedlings, but seedlings with mycorrhizae were less affected by acid mist than were nonmycorrhizal seedlings. Simulated acid mist also retarded mycorrhiza formation. Key words: mycorrhizae, phosphorus content, Pinus thunbergii, Pisolithus tinctorius, simulated acid mist, transpiration rate.
50
Lukuttsova, N., A. Pykin, A. Lukash, S. Shvachko e V. Krasnyy. "MATHEMATICAL MODELS OF THE DEPENDENCE OF THE STRUCTURAL AND DEFORMATION-STRENGTH PROPERTIES OF THE GYPSUM-WOOD COMPOSITE ON THE COMPONENT COMPOSITION". Bulletin of Belgorod State Technological University named after. V. G. Shukhov 8, n. 7 (28 aprile 2023): 17–26. http://dx.doi.org/10.34031/2071-7318-2023-8-7-17-26.
Abstract (sommario):
The production of cement-wood composites (CWC) is difficult due to the presence of extractable substances in the wood filler, which have a negative effect on the hydration of cement, the shape and size of the resulting crystalline hydrates, and the setting time, which leads to a decrease in the strength characteristics of the CWC. Gypsum-wood composites (GWC), in contrast to CWC, are less sensitive to the effects of extractable substances, but they are characterized by low strength and deformability. In order to improve the structural and deformation-strength properties of the GWC, the article presents a mathematical modeling of the effect of the component composition on the average density, open porosity, compressive strength and modulus of elasticity of a gypsum-wood composite for the installation of partitions and enclosing structures in buildings for various purposes. Mathematical models of the dependence of GWC properties on the amount of building gypsum, urea-formaldehyde resin and wood filler from freshly cut hardwood are presented. According to Student's and Fisher's criteria, an assessment was made of the statistical significance and adequacy of the obtained mathematical models, which make it possible to determine the rational values of recipe factors in the manufacture and operation of GWC with an average density of 1250-1370 kg/m3, an open porosity of 25-36%, and a compressive strength of 25-30 MPa, modulus of elasticity 1210-1780 MPa.