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  • cation exchange resin  (2)
  • Gross phosphorus mineralization and immobilization  (1)
  • Hieracium invasion  (1)
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  • 1
    Electronic Resource
    Electronic Resource
    Carbon and phosphorus transformations during decomposition of pine forest floor with different phosphorus status (1998)
    Springer
    Biology and fertility of soils 27 (1998), S. 197-204 
    Details
    ISSN: 1432-0789
    Keywords: Key words Forest floor ; Microbial phosphorus ; Microbial carbon ; C:P ratio ; Gross phosphorus mineralization and immobilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Information on the mineralization of inorganic phosphate (Pi) from organically bound P (Po) during decomposition of forest floor and soil organic matter is vital for understanding P supply in forest ecosystems. Carbon (C) and phosphorus (P) fluxes were determined for forest floor samples from three Pinus radiata plots which had received no P (Control), 62.5 kg P ha–1 (Low P) and 125 kg P ha–1 (High P) 20 years before sampling. The P concentration of the forest floor samples had increased with fertilizer application, and the C:P ratio ranged between 585 and 1465. During a 9-week laboratory incubation 8.2–19.0% of the forest floor C was evolved as CO2-C. The amount of CO2 evolved from the forest floor of the Control plot was more than twice the amounts from the Low P and High P plots. There was little change in net P mineralization in the Control and Low P treatments throughout the incubation, but it increased slightly for the High P samples, suggesting a critical forest floor C:P ratio of 550 for net P mineralization. Changes in the 32P-specific activities of the Pi and microbial P pools during incubation, and concurrent changes in microbial-32P and 32Pi, indicated internal P cycling between these pools. The rate of internal P cycling varied with forest floor quality, and was highest in the High P forest floor. The High P samples had microbial C:P ratios of 22 : 1 which remained constant during the incubation, suggesting the microorganisms had adequate P levels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740050420
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Changes in soil microbial biomass, metabolic quotient, and organic matter turnover under Hieracium (H. pilosella L.) (1999)
    Springer
    Biology and fertility of soils 30 (1999), S. 232-238 
    Details
    ISSN: 1432-0789
    Keywords: Key words Tussock grassland ; High country ; Microbial biomass ; Organic C and N turnover ; Hieracium invasion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  In New Zealand Hieracium is an opportunistic plant that invades high country sites more or less depleted of indigenous vegetation. To understand the invasive nature of this weed we assessed the changes in soil C, N and P, soil microbial biomass C, N and P contents, microbial C : N and C : P ratios, the metabolic quotient, and turnover of organic matter in soils beneath Hieracium and its adjacent herbfield resulting from the depletion of tussock vegetation. The amounts of soil organic C and total N were higher under Hieracium by 25 and 11%, respectively, compared to soil under herbfield. This change reflects an improvement in both the quantity and quality of organic matter input to mineral soil under Hieracium, with higher percentage organic C and a lower C : N ratio. The microbial biomass C, N and P contents were also higher under Hieracium. The amount of C respired during the 34-week incubation indicated differences in the nature of soil organic matter under Hieracium, the unvegetated "halo" zone surrounding Hieracium patches, and herbfield (depleted tussock grassland). Decomposition of organic matter in these zones showed that the Hieracium soil had the greatest rate of CO2 respired, and the halo soil had the lowest. We relate the enhanced organic C turnover to the invasive nature of Hieracium. Net N mineralization was significantly lower from the Hieracium soil (57 mg N g–1 soil N) than from herbfield and halo soils (74 and 71 mg N g–1 soil N, respectively), confirming that the nature of organic N in Hieracium soil is different from adjoining halo and herbfield soils. It seems plausible that specific compounds such as polyphenols and lignins released by Hieracium are not only responsible for increased organic N, but also control the form and amount of N released during organic matter transformations. We conclude that the key to the success of Hieracium in the N-deficient South Island high country of New Zealand lies in its ability to control and sequester N supply through modifying the soil organic matter cycle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740050613
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  • 3
    Electronic Resource
    Electronic Resource
    A simplified resin membrane technique for extracting phosphorus from soils (1990)
    Springer
    Nutrient cycling in agroecosystems 24 (1990), S. 173-180 
    Details
    ISSN: 1573-0867
    Keywords: Phosphate ; resin beads ; resin membranes ; resin-strips ; anion exchange resin ; cation exchange resin ; P sorption capacity ; exchangeable Ca ; phosphate rocks
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A simplified procedure for determining the amount of phosphate (P) extracted from soils by ion exchange resin membranes is reported. Strips of anion (HCO 3 - form) and cation (Na+ form) exchange membrane were shaken with suspensions of soil in deionised water for 16–17 hours. After shaking, the strips were thoroughly rinsed in deionised water before the phosphate retained on the anion exchange resin strip was determined by shaking the strip directly with phosphate reagent. Compared to the common use of resin beads in nylon mesh bags, this resin membrane procedure is simpler, more convenient, and because an elution step is omitted, less time consuming. The mixed resin membrane method for soil phosphate extraction was compared to the use of resin bags on four New Zealand soils, contrasting in P sorbing capacity and exchangeable calcium. The soils were preincubated with and without 240 mg P kg−1 soil with three P sources of different solubilities. The resin strips extracted amounts of P which were closely correlated (R2 = 0.972) with that extracted by the resin bags. The amounts of P extracted by the mixed resin procedure were in proportion to the solubility of the P sources in each soil.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01073586
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Development and evaluation of an improved soil test for phosphorus: 1. The influence of phosphorus fertilizer solubility and soil properties on the extractability of soil P (1992)
    Springer
    Nutrient cycling in agroecosystems 33 (1992), S. 81-91 
    Details
    ISSN: 1573-0867
    Keywords: Anion exchange resin ; Bray 1 ; cation exchange resin ; Colwell ; exchangeable Ca ; P dissolution ; P fractionation ; P sorption capacity ; P tests ; Phosphate rocks ; Olsen ; Truog
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The objective of this work was to develop and evaluate a soil test suitable for estimating the phosphorus status of soils whether they were fertilized with soluble or sparingly soluble P fertilizers or both. Four New Zealand soils of contrasting P sorption capacity and exchangeable Ca content were incubated alone or with monocalcium phosphate (MCP), reactive North Carolina (NC) phosphate rock or unreactive Florida (FRD) rock, at 240 mg P kg−1 soil, to allow the P sources of different solubilities to react with each soil and provide soil samples containing different amounts of extractable P, Ca and residual phosphate rock. The phosphorus in the incubated soils was fractionated into alkali soluble and acid soluble P fractions using a sequential extraction procedure to assess the extent of phosphate rock dissolution. Eight soil P tests [three moderately alkaline — Olsen (0.5M NaHCO3) modified Olsen (pretreatment with 1M NaCl) and Colwell; three acid tests — Bray 1, modified Bray 1 and Truog; and two resin tests — bicarbonate anion exchange resin (AER) and combined AER plus sodium cation exchange resin (CER)] were assessed in their ability to extract P from the incubated soils. The 0.5M NaHCO3 based alkaline tests could not differentiate between the Control and FRD treatments in any soil nor between the Control, NC and FRD treatments in the high P sorption soils. The acid extractants appeared to be affected by the P sorption capacity of the soil probably because of reabsorption of dissolved P in the acid medium. The AER test gave results similar to Olsen. Only the combined AER + CER test extracted P in amounts related to the solubility of the P sources incubated with each soil. Furthermore, when soil samples were “spiked” with FRD and NC and extracted immediately, the P extracted by the AER + CER test, over and above the control soils, increased with the amount and chemical reactivity of the rocks. There was no extraction of rock P by any of the alkaline extractions. Increases in the amounts of P extracted (ΔP) by each soil test from the fertilized soils, over and above the control soils were compared with the amounts ofP dissolved from the fertilizers during incubation (measured by P fractionation). Soil P sorption capacity had least influence on the amounts of P extracted by the AER + CER and Colwell tests. However, the Colwell test was unable to differentiate between all P sources in all four soils and suffered from the disadvantage of producing coloured extracts. The AER + CER test appeared to have the potential to assess the available P status of soils better than the other tests used because of its ability to extract a representative portion of residual PR (in accordance with the amount and reactivity) and dissolved P, and thus to differentiate between fertilizer treatments in all four soils.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01058012
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    Paper (German National Licenses)
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