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  • phosphorus
  • Springer  (120)
  • 1985-1989  (120)
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  • Springer  (120)
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  • 1
    ISSN: 1420-9055
    Keywords: sediments ; cyanobacteria ; Microcystis ; bacterial biomass ; bacterial production ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The seasonal variation of microbial biomass and activity in the surface sediments (0–10 cm) of the shallow, eutrophic Lake Vallentunasjön was followed during one year. “Overwintering”Microcystis colonies dominated the microbial community during all seasons, constituting 60–90% of the total microbial biomass. Expressed on an areal basis, the benthic biomass was, throughout the year, larger than or similar to the planktonic biomass during the peak of the summer bloom, indicating an ability of the colonies to survive in the sediments for extended periods. Abundance of “other”, non-photosynthetic bacteria varied in the range 3.0–15.5 · 1010 cells g−1 d. w. over the year with minimum values in summer and maximum values in autumn in connection with the sedimentation of theMicrocystis bloom. A substantial part of the non-photosynthetic bacteria, up to circa 40%, was associated with the mucilage of healthyMicrocystis colonies. Bacterial production (3H-thymidine incorporation) appeared to be strongly temperature dependent and less influenced by the seasonal sedimentation pattern. Our data indicate an increasing proportion of non-growing cells in autumn and winter. Biomass-bound phosphorus constituted a significant portion, circa 10%, of the phosphorus content in Lake Vallentunasjön sediments. This pool has normally been overlooked in studies on phosphorus dynamics in lake sediments. Different mechanisms whereby organic phosphorus can be released from the sediments are discussed.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1420-9055
    Keywords: Particles ; phosphorus ; watersheds ; snow ; frost ; soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Hydrological processes are known to have a considerable effect on nutrient transport from agricultural land to watercourses. In cold temperate regions peak discharges are caused not only by storm conditions but also by melting of snow and frost. The objective of this work was to investigate the effects of snow and frost melt on concentrations of phosphorus and suspended solids. The samples were taken using flowweighted automatic sampling techniques from two agricultural drainage basins. During the beginning of the snowmelt period the concentration of suspended solids was rather low by comparison with the total phosphorus concentration and the discharge. The different behaviour compared with the relationships found during storm conditions was probably caused by continuous extraction of the soil surface by low ionic concentration melt water, and to some extent by leaching from plant residues. The gradual decrease of total phosphorus concentration during the frost thawing period could be attributed to the gradually increasing proportion of the subsurface and ground water discharge in the runoff.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Human ecology 13 (1985), S. 209-240 
    ISSN: 1572-9915
    Keywords: catchment-ecosystem ; nutrient-budget ; anthropogenic inputs ; nitrogen ; phosphorus ; eutrophication ; agricultural policies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Ethnic Sciences
    Notes: Abstract The catchment-ecosystem concept is adapted to investigate the nutrient-budget of the highly-modified Colebrooke drainage basin in Northern Ireland. Anthropogenic inputs, mainly manures and fertilizers, account for 86% of the nitrogen and 96% of the phosphorus added to the catchment. These inputs greatly exceed the streamflow outputs, thereby indicating that the flow of nutrients is dominated by agriculture. This is explained by the transformation of traditional mixed farming into more intensive livestock production and is linked to policies encouraging increased agricultural production, amalgamation of farms, afforestation, rural depopulation, and urbanization. Substantial increases in the Nand Poutput of the catchment and further eutrophication of the recipient lake, Lough Erne, are predicted without the implementation of policies to reduce agricultural nutrient losses.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Agroforestry systems 8 (1989), S. 257-265 
    ISSN: 1572-9680
    Keywords: Nitrogen ; phosphorus ; potassium ; rooting density ; root biomass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Nutrient competition between interplanted species is investigated using mechanistic modelling. Though tree and crop plant roots may occupy the same soil volume, nutrient competition is seen to be dependent on soil supply mechanisms. Model simulations illustrate the effects of nutrient diffusion rate, mobility/soil interaction, root diameter, soil moisture content, and rooting density on nutrient concentration gradients governing uptake adjacent to plant roots. These factors, unique for each nutrient and soil, combine to determine the potential for competition in agroforestry plantings. Nutrient competition is most likely for the more mobile nutrients and mechanistic modelling can be used to select tree and crop species with superior rooting and physiological characteristics for interplantings to better manage below-ground competition.
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  • 5
    ISSN: 1572-9680
    Keywords: Theobroma cacao ; shade trees ; Erythrina poeppigiana ; Cordia alliodora ; modelling ; organic matter ; nitrogen ; phosphorus ; potassium ; calcium ; magnesium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Models for cycles for organic matter and nutrients element (N, P, K, Ca and Mg) are presented for the agroforestry systems of cacao (Theobroma cacao) withCordia alliodora orErythrina poeppigiana in Turrialba, Costa Rica. For the models, system reserves (soil, humus, vegetation divided into leaves, branches, stems, fine roots, fruits) and transference between compartments (production and decomposition of litter residues) inputs (fertilizer, rainfall) and outputs (harvests) of the system are considered. The implications of the models are discussed in detail. Aspects of net primary production in the systems studied are considered. N fixation is calculated on the basis of balances. Analysis of soil water showed high variations that coincided with rainfall patterns and pruning of theE. poeppigiana.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Bulletin of experimental biology and medicine 101 (1986), S. 135-138 
    ISSN: 1573-8221
    Keywords: phosphorus ; oral mucosa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
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  • 7
    ISSN: 1573-5036
    Keywords: calcareous soil ; chemical inactivation ; copper ; iron chlorosis ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Results of a field trial designed to study the effects of soil-applied phosphorus and copper on the incidence of iron chlorosis in garden peas showed that there were significant reductions in chlorophyll content and peroxidase activity in leaves of plants treated with phosphorus and copper. However, foliar spray of Fe-EDDHA, a stable iron chelate, had no effects on these parameters. Green pod yield of peas was also found significantly reduced with phosphorus and copper applications. But Fe-EDDHA caused significant increase in pod yield. It is suggested that excess of P and Cu in leaves interfere with metabolic translocation of iron and render Fe inactive for chlorophyll synthesis.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 109 (1988), S. 171-179 
    ISSN: 1573-5036
    Keywords: Black Solod ; inflow ; magnesium ; nitrogen ; phosphorus ; potassium ; root efficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A field study with barley was conducted in 1984 and 1985 to provide data on uptake rates of N, P, K and Mg and their variation as the growing season progressed. Two varieties were grown: Galt in 1984 and Otal in 1985. Soil fertility was maintained at or near optimum conditions. Samples were obtained approximately every 10 days for shoot dry weight, nutrient content and root length measurements. The approximate method (Williams, 1948) traditionally used for calculating uptake rates was found to be invalid for most of the nutrients studied. The method used for measuring uptake rates was the functional approach proposed by Hunt (1973). Inflow,i.e. uptake rate per unit root length, of plant nutrients, decreased with time. However, maximum uptake rates measured in kg ha−1d−1 occurred at about 50 days from sowing because of increasing root length density with time. Inflow or uptake rates were low in 1985 because of moisture deficiency, and grain yield (0.89 t ha−1) was severely depressed. This study demonstrated that Hunt's method is superior and more advantageous than the traditional, approximate method.
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  • 9
    ISSN: 1573-5036
    Keywords: copper ; Glomus aggregatum ; phosphorus ; Tropeptic Eutrustox ; zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Response ofLeucaena leucocephala (Lam) de Wit to rock phosphate application and inoculation with the vesicular-arbuscular mycorrhizal (VAM) fungusGlomus aggregatum (Schenck and Smith emend Koske) was evaluated in a pot experiment. VAM colonization increased as rock phosphate application increased. Using phosphorus concentration in pinnules as an indicator of VAM activity, significant VAM activity occurred at 25 days after planting at the lower levels of rock phosphate application (0, 0.34 and 0.68 g P kg−1). The time required for significant VAM activity was shortened by 5 days at the higher P levels (1.36, 2.72 and 5.44 g P kg−1). The highest VAM activity was associated with the highest rate of rock phosphate application. Inoculation withG. aggregatum significantly increased the uptake of Cu, P and Zn and dry-matter yield at all levels of rock phosphate applied. Copper concentrations in roots of mycorrhizal Leucaena were significantly higher than that of shoots. The results indicated that Leucaena in symbiotic association with VAM fungi effectively utilized P from rock phosphate. However, high rates of rock phosphate are required to attain growth comparable to that obtained with the application of water-soluble phosphate.
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  • 10
    ISSN: 1572-9680
    Keywords: cacao ; shade trees ; modelling ; organic matter ; nitrogen ; phosphorus ; potassium ; erythrina ; cordia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The agroforestry systems of cacao (Theobroma cacao) under laurel (Cordia alliodora) and cacao under poro (Erythrina poeppigiana) were studied at CATIE, Turrialba, Costa Rica. An inventory was taken of the organic matter and nutrients (N, P, K, Ca, and Mg) separating the species into their compartments (leaves, branches, trunks and roots). Studies of the litter and of the mineral soil (0–45 cm) yielded these results: Patterns of nutrient accumulation are discussed in relation to the characteristics of these agroforestry systems.
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