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  • Sudan  (38)
  • Nitrogen  (30)
  • Springer  (68)
  • Cambridge University Press
  • Wiley
  • 1980-1984  (68)
  • 1975-1979
  • 1984  (68)
Collection
Keywords
Publisher
  • Springer  (68)
  • Cambridge University Press
  • Wiley
Years
  • 1980-1984  (68)
  • 1975-1979
Year
  • 1
    Electronic Resource
    Electronic Resource
    A concise simulation model for interpreting N-fertilizer trials (1984)
    Springer
    Nutrient cycling in agroecosystems 5 (1984), S. 355-369 
    Details
    ISSN: 1573-0867
    Keywords: Nitrogen ; fertilizer ; dynamic model ; sugar beet
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A concise model is described for calculating day-to-day increments in nitrogen uptake and dry matter of crops grown with different levels of N-fertilizer. Inputs are the initial distribution of inorganic-N down the profile, the maximum yield, the maximum depth of rooting, and the mineralization rate. The validity of the model was tested against measurements of the %N and total dry weights of storage roots and foliage in nine N-fertilizer trials with sugar beet, six of which included both irrigated and unirrigated treatments. Agreement between the model and experiment was good except in one experiment severely attacked by virus yellows. Simulation studies with the model indicated that no simple correlation would be expected between N fertilizer requirement and any single indicator of N availability for crops grown under a wide range of conditions in the UK.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01049116
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  • 2
    Electronic Resource
    Electronic Resource
    Effects of stream channelization on exports of nitrogen and phosphorus from north Carolina coastal plain watersheds (1984)
    Springer
    Environmental management 8 (1984), S. 151-160 
    Details
    ISSN: 1432-1009
    Keywords: Watersheds ; Budgets ; Nitrogen ; Phosphorus ; Channelization ; Swamps ; Floodplain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Nitrogen and phosphorus exports from channelizedstream watersheds were elevated over those from nearby natural swamp-stream watersheds. Nitrate exports were significantly greater from channelized-stream watersheds, and higher exports were attributed to faster groundwater drawdown, continual streamflow, and transformation of former floodplain to croplands following channelization. Exports of total organic nitrogen and total nitrogen were also significantly greater from channelized-stream watersheds. Differences in the exports of ammonium, filterable reactive phosphorus, and filterable unreactive phosphorus between the two watershed types were not detectable. Particulate phosphorus exports were significantly higher from channelized-stream watersheds, presumably because of greater erosion potential of nearby croplands and steep channel banks in the altered watersheds. The presence of nonpoint sources of pollution increased watershed exports of nutrients regardless of stream morphology. Examination of nutrient budgets for a portion of swamp floodplain at the base of one natural-stream watershed revealed that changes in local groundwater hydrology and stream morphology associated with channelization appeared to have greater effect on nutrient exports than simply the loss of bordering forested floodplain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01866936
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  • 3
    Electronic Resource
    Electronic Resource
    Botryococcus braunii carbon/nitrogen metabolism as affected by ammonia addition (1984)
    Springer
    Archives of microbiology 140 (1984), S. 101-106 
    Details
    ISSN: 1432-072X
    Keywords: 5-aminolevulinic acid ; Ammonia ; botryococcus braunii ; Botryococcenes ; Carbon ; Hydrocarbon ; Metabolism ; Nitrogen ; Resting state ; Terpenoids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Carbon metabolism in photosynthesizing and respiring cells of Botryococcus braunii was radically changed by the presence of 1 mM NH4Cl in the medium, when the so-called “resting state” previously had been subjected to a nitrogen-deficient medium. Ammonia addition to the algae photosynthesizing with 14C-labelled HCO 3 - almost completely inhibited the synthesis of 14C-labelled botryococcenes and other hexane-extractable compounds, and also inhibited the formation of insoluble compounds; however, it resulted in a large increase in the synthesis of alanine, glutamine, other amino acids, and especially of 5-aminolevulinic acid. Total CO2 fixation decreased about 60% and O2 evolution decreased more than 50%. CO2 fixation in the dark with ammonia present led to labelled products derived from phosphoenolpyruvate carboxylation, such as glutamine, glutamate, and malate. Respiratory uptake of O2 increased by about 70%. The inhibition of terpenoid synthesis and increased synthesis of C5 amino acids by Botryococcus upon ammonia addition indicates 1) a diversion of acetyl coenzyme A from synthetic pathways leading to terpenoids and 2) increased operation of pathways leading to the synthesis of amino acids, especially 5-aminolevulinic acid, a precursor to chlorophyll biosynthesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00454910
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  • 4
    Electronic Resource
    Electronic Resource
    Genetics of nitrogen metabolism and physiological/biochemical selection for increased grain crop productivity (1984)
    Springer
    Theoretical and applied genetics 67 (1984), S. 97-111 
    Details
    ISSN: 1432-2242
    Keywords: Genetics ; Nitrogen ; Grain crops ; Selection ; Plant breeding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary It is necessary to increase protein productivity of grain crops to meet present and future world protein requirements. Conventional plant breeding methodology has been to select genotypes with enhanced yield or grain protein concentration. In addition to this determination of end product, we suggest measurements of a number of physiological and biochemical processes of nitrogen (N) metabolism which precede plant maturity as selection criteria for enhanced N metabolism and grain crop productivity. The measurement across the growing season of genotypic variation in components of N metabolism would constitute a physiological/biochemical selection program to be incorporated with the determination of harvestable end product. A properly designed physiological/biochemical selection program would integrate the effects of plant genotype, environment, and their interactions allowing identification of the factors limiting productivity of particular genotypes, and would also estimate end product. Our review of literature pertinent to whole plant N metabolism suggests that such a selection program initially include NO 3 - uptake, N2 fixation, N accumulation, N remobilization, seed protein synthesis, and Nitrogen Harvest Index.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00317013
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  • 5
    Electronic Resource
    Electronic Resource
    The uptake of soil and fertilizer-nitrogen by barley growing under Scottish climatic conditions (1984)
    Springer
    Plant and soil 76 (1984), S. 49-57 
    Details
    ISSN: 1573-5036
    Keywords: Ammonium ; Barley ; Fertilizer ; Mineralization ; Nitrate ; Nitrogen ; Nitrogen-15
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Field experiments were carried out using15N-labelled calcium nitrate, to investigate the relative uptake by barley of fertilizer-N and soil-N. On imperfectly drained till soils uptake of soil-N increased with increasing rate of fertilizer, but remained constant on a brown sand, possibly due to more efficient root exploration in the latter soil. In four out of five seasons, late uptake of soil-derived N was a major feature, and uptake from ploughed soil as compared with uptake from direct-drilled soil was correlated with seasonal rainfall patterns. Significantly higher quantities of both fertilizer- and soil-derived N were taken up by winter barley than by spring barley, reflecting the longer growth period and higher dry matter yield from the former crop.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02205566
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  • 6
    Electronic Resource
    Electronic Resource
    Biological and biochemical analysis of soils (1984)
    Springer
    Plant and soil 76 (1984), S. 127-137 
    Details
    ISSN: 1573-5036
    Keywords: Adenylate pool ; Biomass volume ; CO2 evolution ; Chitin ; DNA ; Electron microscopy ; Enzymes ; Fluorescent antibody ; Fumigation-respiration ; Fungi Histochemistry ; Imunofluorecence ; Jones-Mollison technique ; Microcosms ; Monoclonal antibodies ; Nitrogen ; Nutrients ; Oxygen consumption ; Phosphorus ; Phytotoxins ; Plate counts ; Rhizobium ; Rhizosphere ; Sulphur ; Xenobiotics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary There is an immense literature on biological and biochemical analyses of soils. Such analyses have revealed the enormous richness of species in soil and their vast range of metabolic potentials and ecological diversity. Accordingly, the approaches used to investigate the soil biota and its biochemistry usually have to be modified or adapted depending upon the purpose of the investigation. Studies of micro-organisms in the soil environment, are complicated because microbial cells are commonly attached to surfaces where they live side-by-side with other populations in consortia usually containing different morphological and physiological types. Such assemblages of organisms cannot be described quantitatively using cultural techniques, such as plate counts, which underestimate both cell numbers and viable biomass. The development of more powerful observational and staining techniques has improved our knowledge of the diverse morphological and biochemical composition of soil micro-communities. Such findings have been amplified at a grosser level by laboratory studies with multi-component systems (microcosms) to mimic field situations and to assess the range of biochemical potentials of microbial consortia. But despite notable advances in analytical methods we are still, with a few exceptions, unable to detect or identify those microorganisms which carry out specific biochemical transformations or determine whether particular cells are alive, dormant or dead at the time of observation. Considerable work has been done to define some of the fundamental ecological attributes of microbial assemblages in soil. Productive work on the metabolic activities of the soil microbiota, specially geochemical transformations of C, N, S and P, has been under way for more than a century. But only in more recent years have more sensitive and reproducible analytical methods become available to measure viable biomass in soil. This will enable some insight to be gained into the role that microbial biomass plays as a labile source and sink for plant nutrients.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02205573
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  • 7
    Electronic Resource
    Electronic Resource
    Denitrification in field soils (1984)
    Springer
    Plant and soil 76 (1984), S. 213-226 
    Details
    ISSN: 1573-5036
    Keywords: Acetylene ; Arable crops ; Cultivation ; Denitrification ; Drainage ; Gas ; Chromatography ; Grassland ; Inorganic N fertilizer ; Irrigation ; Nitrogen ; Nitrous oxide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Recent denitrification research is reviewed to answer questions a) how much N is lost from the soil as N2 and N2O and b) how do agronomic practices affect this loss? The methods used to quantify denitrification are also discussed. Gaseous losses of inorganic N range between the equivalent of 0 to 20 per cent of the fertilizer N applied to arable soils and 0–7 per cent on grassland soils. Losses are greater on undrained land and also after using direct drilling to establish arable crops. Appendix 1 summarizes reported measurements of gaseous N losses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02205581
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  • 8
    Electronic Resource
    Electronic Resource
    Concepts of soil organic matter transformations in relation to organo-mineral particle size fractions (1984)
    Springer
    Plant and soil 76 (1984), S. 287-295 
    Details
    ISSN: 1573-5036
    Keywords: Carbon ; Concepts ; Cultivation effects ; Nitrogen ; Nitrogen-15 ; Organic matter models ; Particle size fractions ; Phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Changes in the composition of organo-mineral particle size fractions as a result of cultivation of a grassland soil are discussed with reference to models of soil organic matter formation and turnover. The data presented indicated that physically stabilized organic matter is an important reservoir, with an intermediate turnover time, which is responsible for nutrient supply in agricultural soils. Possible mechanisms of stabilization and mobilization of organic matter are presented in the light of the arrangement of organic and inorganic components of the soil.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02205587
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  • 9
    Electronic Resource
    Electronic Resource
    Litterfall and nutrient returns in red alder stands in western Washington (1984)
    Springer
    Plant and soil 79 (1984), S. 343-351 
    Details
    ISSN: 1573-5036
    Keywords: Alnus rubra ; Aluminum ; Annual returns ; Essential elements ; Litterfall ; Leaf litter ; Nitrogen ; Nutrients ; Red alder
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Litterfall was collected over 1 year from eight natural stands of red alder growing on different sites in western Washington. The stands occurred at various elevations and on different soils, and differed in age, basal area, and site index. Most litterfall was leaf litter (average 86 percent). Amounts of litterfall and leaf litter varied significantly (P〈0.05) among the sites. Average weights of litterfall and leaf litter in kg ha−1 yr−1, were 5150 and 4440, respectively. Weight of leaf litter was not significantly (P〈0.05) related to site index, stand age, or basal area. The sites varied significantly (P〈0.05) in concentrations of all elements determined in the leaf litter, except Zn. Average chemical concentrations were: N, 1.98 percent; P, 0.09 percent; K, 0.44 percent; Ca, 1.01 percent; Mg, 0.21 percent; S, 0.17 percent; SO4−S, nil; Fe, 324 ppm; Mn, 311 ppm; Zn, 53 ppm; Cu, 13 ppm; and Al, 281 ppm. There were significant correlations between some stand characteristics and concentrations of some elements, and among the different chemical components of the leaf litter. Important correlations were found between stand age and P concentration (r=−0.84,P〈0.01); weight of leaf litter and P concentration (r=0.74,P〈0.05); weight of leaf litter and K concentration (r=0.71,P〈0.05); concentrations of N and S (r=0.81,P〈0.05); and concentrations of Fe and Al (r=0.98,P〈0.01). Returns of the different elements to the soil by leaf litter varied among the different sites. Average nutrient and Al returns, in kg ha−1 yr−1, were: N, 82; Ca, 41; K, 19; Mg, 8; S, 7; P, 4; Fe, 1; Mn, 1; Al, 1; Zn, 0.2, and Cu, 〈0.1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02184327
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  • 10
    Electronic Resource
    Electronic Resource
    Cycling of nitrogen in modern agricultural systems (1984)
    Springer
    Plant and soil 76 (1984), S. 3-21 
    Details
    ISSN: 1573-5036
    Keywords: Agriculture ; Barley ; Budgets ; Fauna ; Fertilizers ; Global cycles ; Lucerne ; Meadow fescue ; Microorganisms ; Nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Agro-ecosystems have developed from mixed- and multiple-cropping systems with relatively closed N cycles to intensively managed monocultures with large N inputs in the form of commercial fertilizers. Cultivation of increasingly larger areas of land has resulted in substantial losses of soil organic matter and N. Also, the move from slash and burn agriculture to intensively ploughed systems has resulted in losses through increased erosion. The use of N fertilizers has increased rapidly toca. 60 Tg N yr−1 (1980/81), which is equivalent to at least 40% of the N fixed biologically in all terrestrial systems and 36% more than is fixed in all croplands. On a global scale, the major losses of N from agro-ecosystems are estimated to be: harvest, 30 Tg; leaching, 2 Tg; erosion, 2–20 Tg; denitrification 1–44 Tg; and ammonia volatilization, 13–23 Tg. However, the data base is very crude and several estimates may be wrong by as much as one order of magnitude. Additions of N fertilizers have both direct and indirect effects on soil microorganisms. The possible importance of such effects is briefly discussed and a specific example is given on long-term effects on soil microbial biomass and nitrification rates in 27-year-old cropping systems with different N additions: (i) 0 kg N ha−1 yr−1, (ii) 80 kg N ha−1 yr−1, (iii) farmyard manureca. 80 kg N ha−1 yr−1. Few detailed N budgets exist for agro-ecosystems, despite its major importance as a limiting plant nutrient and the large losses of N from such systems. In conclusion, preliminary nitrogen budgets for four cropping systems (barley receiving 0 or 120 kg N ha−1 yr−1; meadow fescue ley with 200 kg N ha−1 yr−1 and a lucerne ley) are presented, with special attention to N flow through the soil organisms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02205563
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  • 11
    Electronic Resource
    Electronic Resource
    Tillage effects on nitrogen uptake by maize from fine textured soils in the northwestern Corn Belt, USA (1984)
    Springer
    Plant and soil 76 (1984), S. 67-73 
    Details
    ISSN: 1573-5036
    Keywords: Maize ; Nitrogen ; Nitrogen uptake ; Tillage ; Zea mays L
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Nitrogen (N) accumulation data from a replicated field study were fitted to a tanh (time) function and the derivate obtained to determine relative maximum rates of accumulation by maize. Both positive and negative effects of tillage on N accumulation rates were observed. Most of the N accumulation occurred over a 30-day period and time of N accumulation was not affected by tillage. Tilled profiles tend to contain greater NO3−N, greater aeration, and lower moisture contents than untilled profiles, and these characteristics interact to affect plant N accumulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02205568
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  • 12
    Electronic Resource
    Electronic Resource
    Copper deficiency inPinus radiata planted in a podzol in Victoria, Australia (1984)
    Springer
    Plant and soil 77 (1984), S. 73-86 
    Details
    ISSN: 1573-5036
    Keywords: Fertiliser ; Foliar analysis ; Nitrogen ; Phosphorus ; Pinus radiata ; Potassium ; Soil organic matter ; Steenbjerg effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Copper deficiency inPinus radiata in Gippsland, Victoria was found to be associated with acid, organic-rich sandy podzols. A trial designed to find a Cu supplement for P and NPK fertilisation on these soils showed significant growth in stem-length following Cu-solution treatment in the nursery, and Cu fertiliser applied in the field up to at least 13.5 kg Cu ha−1. The Steenbjerg effect was evident in foliar concentrations of nutrients following fertilisation; this makes diagnosis from foliar analysis difficult. Foliar Cu∶N ratios proved a more sensitive indicator of Cu fertiliser treatment than either Cu or N alone. Two phases of seasonal drainage and podzol development were identified in the experiment. Trees growing on the better-drained, more acid soil with a high content of organic matter responded better to Cu fertiliser.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02182813
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  • 13
    Electronic Resource
    Electronic Resource
    Effect of substrate concentration, inorganic nitrogen, O2 concentration, temperature and pH on dehydrogenase activity in soil (1984)
    Springer
    Plant and soil 77 (1984), S. 285-293 
    Details
    ISSN: 1573-5036
    Keywords: Dehydrogenase ; Electron transport system ; Nitrogen ; Oxygen pH ; Substrate ; Temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Dehydrogenase activity was measured in a sandy loam soil under a variety of incubation conditions using the reduction of 2-(p-iodophenyl-3-(p-nitrophenyl)-5-phenyl tetrazolium chloride (INT) to iodonitrotetrazolium formazan (INT-formazan). There was a high positive correlation between dehydrogenase activity and substrate concentration, incubation temperature, and soil pH. Dehydrogenase activity also displayed a high negative correlation with O2 concentrations. Ammonium sulfate at concentrations from 40 to 120 μg/g soil had no significant effect on dehydrogenase activity. However, at concentrations of 160 and 200 μg/g, dehydrogenase activity was significantly reduced. Potassium nitrate at concentrations ranging from 40 to 200 μg/g had no significant effect on soil dehydrogenase activity, whereas sodium nitrite significantly inhibited activity at concentrations of 120 and 160 μg/g soil.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02182931
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  • 14
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    Electronic Resource
    The release, diffusion and nitrification of nitrogen in soils surrounding sulfur-coated urea granules (1984)
    Springer
    Plant and soil 78 (1984), S. 345-356 
    Details
    ISSN: 1573-5036
    Keywords: Ammonium sulfate ; Nitrification ; Nitrogen ; Slow-release fertilizers ; Sulfur-coated urea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary We have compared sulfur-coated urea granules (SCU) with ammonium sulfate granules (AS) in regard to nitrogen (N) release, diffusion, nitrification and the effect of irrigation. In the experiments plastic containers were filled with six layers of soil, separated from each other by fine nylon cloths. The fertilizer granules were placed between the two central layers, and irrigation was simulated by application of tap water to the uppermost layer. Nitrogen release from the SCU was slow, and after three months, 29.5% of the applied N remained in the granules. At the end of the experiment there was a deficit of 37.1% N in the case of the AS granules, while there was virtually none with the SCU. Throughout the experiment, N from SCU remained at a relatively even level, while 95% of the N applied as AS had disappeared after irrigation. Nitrification was rapid in both cases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02450368
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  • 15
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    Electronic Resource
    Mineralization of C and N from microbial biomass in paddy soil (1984)
    Springer
    Plant and soil 76 (1984), S. 165-173 
    Details
    ISSN: 1573-5036
    Keywords: Biomass ; Carbon ; Chloroform fumigation ; Drying ; Mineralization flush ; Nitrogen ; Paddy soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Soil samples of paddy fields with different fertilizer managements in Yamaguchi Agricultural Experiment Station, Japan were used to investigate the contribution of microbial biomass to the pool of mobile plant nutrients in paddy soil. The quantities of nutrients mobilized in soils which had been fumigated or dried were closely related to the quantities available in freshly killed biomass. A “KN-factor” (28 days) of 0.24 for the proportion of total N mineralized from dead biomass in paddy soils was obtained. It was observed that the C to N ratio mineralized from freshly killed biomass by chloroform fumigation of paddy soils was nearly 10 under aerobic conditions. For an approximate calculation of biomass C from the flush-N by chloroform fumigation of paddy soils, the equations of (B=33 Fn, 10 days) and (B=26 Fn, 28 days) were indicated. In oven-dried (70°C, 24 h) and rewetted soils, about 66% of N was mineralized from the freshly killed biomass during 28 days of incubation and the remaining 34% was derived from non-biomass organic matter of paddy soils.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02205577
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  • 16
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    Nitrite: a key compound in N loss processes under acid conditions? (1984)
    Springer
    Plant and soil 76 (1984), S. 233-241 
    Details
    ISSN: 1573-5036
    Keywords: Chemo-denitrification ; Iron oxyhydroxide ; Nitrate ; Nitric oxide ; Nitrite ; Nitrogen ; Nitrogen dioxide ; Reduced conditions ; Soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Nitrite is very important in N transformation processes because it is an intermediate product in the aerobic nitrification as well as in the anaerobic denitrification process. Under soil conditions whereby aerobic and anaerobic zones are close to each other, the mobile nitrite can be a link between both N transformation processes. Because of its low stability in acid conditions, nitrite can be a key compound in N loss processes. The results are presented in three sets of incubation experiments using soil+added nitrite before and after oxidation of organic matter; soil+added nitrite and various iron oxide minerals; nitrite solutions without soil but with added ferrous iron. It was found that under acid conditions, soil organic matter as well as the soil mineral phase have a stimulating effect on the nitrite decomposition. Conditions favouring the solubility of Fe(III)-compounds and promoting the formation of Fe2+ increase the nitrite decomposition, even under slightly acid conditions. Of the gaseous decomposition products, only trace amounts of NO2 occur while NO is the major component. Conditions whereby NO and NO2 cannot escape from the medium promote production of some nitrite.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02205583
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  • 17
    Electronic Resource
    Electronic Resource
    Modelling C and N turnover through the microbial biomass in soil (1984)
    Springer
    Plant and soil 76 (1984), S. 257-274 
    Details
    ISSN: 1573-5036
    Keywords: Biomass turnover ; Carbon ; Experimental verification ; Models ; Nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Many mathematical descriptions of C and N transformations in soils have been developed in the last decade, but only a few explicitly model the activity and mass of soil organisms. Great difficulties still exist in establishing basic parameters governing the kinetics of microbial turnover. The present state of the art is discussed briefly. The model of Van Veen and Frissel on C transformations and related mineralization and immobilization of N has been developed further based on laboratory and field data obtained with different Australian soils. Firstly, case studies show the large effects of the frequency of drying and rewetting of soils on the decomposition of organic matter and on the turnover of biomass. Secondly, the more refined model embraces the concept that soils have characteristic capacities to preserve both organic matter and microorganisms. Preservation of microorganisms could result from protection against predation and/or from amelioration of harsh environmental conditions. Biomass formed in excess of a soil's preservation capacity is assumed to die at a relatively high rate. Furthermore, biomass and its immediate organic products of decay are considered to form mainly a closed system from which only small proportions of the products leak out as stabilized materials. These concepts have been tested with data from laboratory experiments in which14C- and15N- labelled substrates and bacteria were added to a clay and sandy soil. Net mineralization of C and N (labelled and unlabelled) and changes in the total and labelled biomass as determined by the chloroform fumigation technique allowed for a thorough testing of these concepts in the manner in which they were included in the model. The fits between experimental observations and model outputs were very close. The model indicated that the contrasting metabolism of both C and N in a clayversus a sandy soil could largely be explained by differences in the capacities of the two soils to preserve microorganisms. The ability of a simulation model to describe accurately not only short-term events,e.g. N cycling during one growing season, but also the same processes over, say a decade, is an important criterion in assessing its predictive power. In this paper some of the results will be discussed of testing the model, developed from a consideration of the aforementioned laboratory studies, for its accuracy in describing the decomposition of plant residues in an 8-year field experiment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02205585
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  • 18
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    Extractable N and P in relation to microbial biomass in UK acid organic soils (1984)
    Springer
    Plant and soil 76 (1984), S. 139-148 
    Details
    ISSN: 1573-5036
    Keywords: Chloroform-fumigation ; Microbial biomass ; Mor humus ; Nitrogen ; Peat ; Phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Samples of peat and mor humus were treated with CHCl3 to kill microbial cells and the amounts of C as CO2, N as soluble- and mineral-N, and P as inorganic-P released by the treatment were compared with estimates of the microbial biomass by the Anderson and Domsch test and ATP determination. Increased amounts of soluble-N and inorganic-P, extracted with 1M KCl and 0.01M CaCl2 respectively, were detected immediately after the fumigation treatment. However, the subsequent rates of production of CO2−C and mineral-N measured during a 10-day incubation period at 25°C were low and variable, resulting in anomalously low estimates of microbial biomass. The flush of inorganic-P was more consistent and, in mor humus, generally related to biomass-C as measured by the Anderson and Domsch test.
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    Dynamics of organic matter in soils (1984)
    Springer
    Plant and soil 76 (1984), S. 275-285 
    Details
    ISSN: 1573-5036
    Keywords: Biomass dynamics ; carbon ; Nitrogen ; Nutrient management ; Soil organic matter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Dynamics of C, N, S, and to some extent P are expressed by a knowledge of the size and turnover rates of plant constituents such as soluble C and N components, cellulose and hemicellulose, and lignin. Soil organic matter constituents include: the microbial biomass as determined chemically or microscopically, non-biomass active components determined by isotopic dilution, stabilized N constituents for which good techniques are not yet available, and resistant or old C and associated N determined by carbon dating. The processes involved in the nutrient transformations and transfers are reasonably well understood. The control mechanisms require further elucidation to be able to extrapolate from the laboratory to the field, and between field sites. Major control mechanisms requiring further insight include the effects of C availability on transformations of C and N. The other control for which every little is known is that of spatial compartmentalization. Compartmentalization ranges from landscape or management sequences to pedogenic layers, rhizosphere-mycorrhizal effects, clay-sesquioxide surfaces, aggregation, localized enzymes, and microbial effects such as membrane boundaries. Control mechanisms for concurrent mineralization-immobilization, the stabilization of microbial products, and the relative role of the biomass as a catalyst rather than as a source-sink for nutrients, must be understood. There is potential for combining a knowledge of microbial production and turnover with that of the roles of the soil organic active fraction as a temporary storehouse for nutrients. This, in conjunction with management techniques such as zero tillage and crop rotation, should make it possible to better utilize soil and fertilizer N, especially in areas of the world where the cost of nutrients is high relative to the value of the crop grown.
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    URL: http://dx.doi.org/10.1007/BF02205586
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  • 20
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    Relationships of bio-climatic zones and lithology with various characteristics of forest soils in Greece (1984)
    Springer
    Plant and soil 79 (1984), S. 101-121 
    Details
    ISSN: 1573-5036
    Keywords: Base saturation ; Bio-climatic zones ; Calcium ; Clay accumulation ; Copper ; C:N ratio ; EDTA ; Forest soils ; Greece ; Iron ; Magnesium ; Manganese ; Nitrogen ; Phosphate ; Potassium ; Soil classification ; Zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Soils derived from a number of different parent materials (lithologies) and developed along a climatic gradient, manifested by the altitudinal succession of natural vegetation zones (Mediterranean, sub-Mediterranean, Mountainous and Pseudoalpine), were sampled throughout mainland Greece. In soils derived from siliceous parent materials low in clay, acidity increase and percent base saturation decreases from the Mediterranean to the Pseudoalpine vegetation zones. Clay illuviation is found mainly in soils developed in the Mediterranean and the sub-Mediterranean zones. No such changes are apparent in clayey soils rich in bases. Organic matter content of the mineral portion of the soil profile increases by a factor of 2 with a decrease in mean annual air temperature of about 10°C. The pattern of change in clay and soil organic matter content with climate is in relatively good agreement with soil development trends in the area, when soil profiles are named according to the FAO-Unesco soil map of the world. Concentrations of Ca and Mg decrease and those of total N, total and extractable P, K, Fe, Mn and Zn increase from the Mediterranean to the Mountainous zone. Within the same zone, however, concentrations of N, Ca, K, Fe, Mn and Zn decrease, but those of Mg, total and extractable P increase with soil depth. The concentrations of most macro- and micronutrients in the humic horizon are several times higher than those in the mineral portion of the soil profile due to biological enrichment.
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  • 21
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    The invasion of Biomphalaria pfeifferi by Schistosoma mansoni miracidia and the development of daughter sporocysts (1984)
    Springer
    Hydrobiologia 110 (1984), S. 227-233 
    Details
    ISSN: 1573-5117
    Keywords: Sudan ; Schistosoma mansoni ; Biomphalaria pfeifferi ; miracidia ; sporocysts ; host-parasite relations ; laboratory studies ; decoy snails
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Laboratory experiments have been carried out to determine the susceptibility of Gezira Biomphalaria pfeifferi snails to S. mansoni miracidia and the relationship between miracidia and daughter sporocyst production at the 10–17 day development stage. The relationship between snail numbers, miracidia numbers and water volume has also been studied. Two non susceptible snails, Bulinus truncatus and Cleopatra bulimoides, both of which occur naturally in Gezira canals, were tested to see if they act as decoys for S. mansoni miracidia. The results showed that the B. pfeifferi are 100% susceptible to S. mansoni invasion, at least to the daughter sporocyst development stage. The more miracidia that penetrated the more daughter sporocysts were produced, however individual variation and overlap were great. When one miracidium was released to find one snail it succeeded in low water volumes (5 m, 50 ml), but failed in 5 litres. When 100 miracidia were released mortality of snails was high suggesting superinfection particularly when only one or five snails were available. Among survivors daughter sporocyst counts were very high. Cleopatra and Bulinus snails do have a decoy effect when present in large numbers. In their presence the number of infected snails was marginally reduced and the number of daughter sporocysts greatly reduced. However, if superinfection is reduced by decoy effect, it is conceivable that Biomphalaria may be protected by decoy snails in circumstances where miracidia counts are high.
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    Feeding and growth of the pearl oyster Pinctada margaritifera (L.) in Dongonab Bay, Red Sea (1984)
    Springer
    Hydrobiologia 110 (1984), S. 241-245 
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    ISSN: 1573-5117
    Keywords: Sudan ; pearl oyster ; feeding ; growth ; Red Sea ; Sudan
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Plankton samples and gut contents of P. margaritifera were analysed monthly from April 1972 to March 1973. Coscinodiscus sp. was the most ingested food by pearl oysters of all ages. However, food variety increased as the oyster grew older. Experiments confirmed the absence of food selectivity in P. margaritifera. Unlike the young ones, the adult showed reduced growth during summer (July–September), which coincides with its spawning season.
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  • 23
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    Location of Biomphalaria pfeifferi by Schistosoma mansoni miracidia in stagnant and running water under field conditions (1984)
    Springer
    Hydrobiologia 110 (1984), S. 235-240 
    Details
    ISSN: 1573-5117
    Keywords: Sudan ; Schistosoma mansoni ; Biomphalaria pfeifferi ; miracidia ; sporocysts ; transmission of schistosomiasis ; host-parasite relations ; ecology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The efficiency of S. mansoni miracidia in locating and infecting Biomphalaria pfeifferi in Gezira canals has been studied under field conditions. When S. mansoni eggs were introduced into clean stagnant water in small field channels, the miracidia hatched to infect 100% of 30 snails in cages at the release point. Fifteen metres upstream and downstream 13% of caged snails were infected but no infections were found in snails 20 m away. When eggs were released into the same canal in flowing water (8.3 cm · s−1), no infections were detected in any of the caged snails placed 0–100 m downstream. Releasing hatched miracidia instead of eggs resulted in infections in all cages at 5 m intervals from 0-100 m. The release of eggs into flowing water was likened to the method by which S. haematobium eggs are deposited during urination. The 0% infection suggests that eggs will be swept away from the point of contamination by the flow. Thus only urination into stagnant water will lead to heavy snail infection rates. When eggs were released into a small pond-like minor canal tail end snail infection rates were only 3%. This was probably due to the larger water volume, smaller number of caged snails, and the presence of vegetation and other fauna which may be decoys or predators. The results highlight how very high snail infection rates can be produced under ideal conditions but also show how large snail and miracidia numbers are required in natural situations.
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    Food and food selection of the Penaeid prawn Penaeus monodon (Fabricius) (1984)
    Springer
    Hydrobiologia 110 (1984), S. 213-217 
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    ISSN: 1573-5117
    Keywords: Sudan ; Penaeus ; food ; food selection ; chemoreception
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A study of food and food selection of Penaeus monodon (Fabricius) on the Sudanese Red Sea coast was carried out. Juveniles feed mainly on algal material. Adults feed on crustacea, annelids, algae, mud and unidentified matter. Adults were opportunistic in their feeding behaviour, but their preference was towards animal protein. Antennae, mouth parts and fore-chelipeds were found to carry long, slender setae which are probably of sensory function. Some setae on the carpus of the endopodite were serrated and seem to be used in grooming. Numerous tufts of setae in the chela of the fore periopods may hold a gustatory function. The inner edges of the chela are lined with a row of peg-like setae, which are probably another site of reception.
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    Primary production and respiration of the phytoplankton in the Blue and White Niles at Khartoum (1984)
    Springer
    Hydrobiologia 110 (1984), S. 57-59 
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    ISSN: 1573-5117
    Keywords: Sudan ; algae ; Blue Nile ; primary productivity ; tropical rivers ; White Nile
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Phytoplankton production and respiration in the Blue Nile and White Nile at Khartoum were measured during the period November 1969–January 1971 using the light and dark bottle technique. Maximum rates of production coincided with periods of maximum phytoplankton densities. In the Blue Nile gross production varied between 0.00 gCm−3d−1 during the flood season and 2.19 gCm−3d−1 (0.49 mgO2l−1h−1) during November 1969. In the White Nile the range was from 0.41 gCm−3d−1 (0.09 MgO2l−1h−1) in May to 3.74 gCm−3d−1 (0.83 MgO2l−1h−1) in November. The maximum rates of respiration in the Blue Nile and White Nile were 0.10 and 0.63 MgO2l−1h−1 respectively. The ratios net:gross production were generally higher in the White Nile than in the Blue Nile.
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    Some algae from the Red Sea Hills in north-eastern Sudan (1984)
    Springer
    Hydrobiologia 110 (1984), S. 61-77 
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    ISSN: 1573-5117
    Keywords: Sudan ; algae ; Nubian desert
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The algae contained in some plankton samples from several localities on four wadi in N.E. Sudan were examined. The observed algae amount to 260 taxa, of which the diatoms, representing 50% of the algal flora, are the most numerous. Other large groups are the blue-green algae (17%) and the green algae (24%) among which the desmids (6%) are rather unimportant.
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    Ecological observations on mangroves of the Red Sea shores of the Sudan (1984)
    Springer
    Hydrobiologia 110 (1984), S. 109-111 
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    ISSN: 1573-5117
    Keywords: Sudan ; mangroves ; Red Sea ; ecology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An ecological survey of the mangrove vegetation in the littoral salt marshes of the Red Sea coast of the Sudan was made during short periods between 1980 and 1982. Avicennia marina (Forsk) Vierh occurs in pure stands of different dimensions in four types of locations. In each location, the responses of Avicennia are expressed in the degree of compactness of aggregation, canopy, height and regeneration potential. Grazing by camels is the primary agent in degradation of accessible locations; salt pans and to a limited extend cutting contribute in part to the process of degradation. The badly damaged aggregations may benefit from protection through control of grazing by nomadic camel tribesmen.
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    Aquatic snails of the Jonglei region, southern Sudan, and transmission of trematode parasites (1984)
    Springer
    Hydrobiologia 110 (1984), S. 247-271 
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    ISSN: 1573-5117
    Keywords: Sudan ; Mollusca ; Gastropoda ; fresh water snails ; trematode parasites ; schistosomiasis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An account is given of the aquatic gastropod molluscs obtained in a survey made to assess future ecological effects of the Jonglei Canal now under construction in the Sudd region of southern Sudan. A total of about 23 species of aquatic snail lives in this region, of which a number are utilised as intermediate hosts by trematode parasites infecting man, livestock and wild herbivores, causing the diseases schistosomiasis, fascioliasis and amphistomiasis. Public health and veterinary authorities should be alert to the possibility that the Jonglei Canal will increase snail populations and raise the prevalence of parasitic diseases.
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    The food and growth of pelagic 0+ Alestes nurse (Characidae) from the Blue Nile, near Khartoum (1984)
    Springer
    Hydrobiologia 110 (1984), S. 273-279 
    Details
    ISSN: 1573-5117
    Keywords: Sudan ; Alestes ; growth ; feeding ; Nile
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The food, feeding habits and growth of 0+ Alestes nurse (Rüppel) from the Blue Nile near Khartoum, was investigated. 0+ A. nurse were observed to change their food from phytoplankton and small zooplankton during their pre-metamorphosis stages, to larger zooplankton (Daphnia spp., Chydorus sp.) and insects (larvae, pupae and imagines) during their post-metamorphosis stage. Their growth in length and weight was characterized by two distinct stanzas; during the first stanza, the fish increased in total length at a rate of 0.196 mm mm−1 wk−1, and in wet weight at a rate of 0.430 g g−1 wk−1. These rates were reduced during the second stanza to 0.046 mm mm−1 and 0.080 g g−1 wk−1, respectively. The calculated value of the exponent b in their length-weight relationship suggested that their growth was allometric.
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    Use of the frontal bone in age determination of Labeo horie (Pisces, Cyprinidae) in Jebel Aulia Reservoir, Sudan (1984)
    Springer
    Hydrobiologia 110 (1984), S. 281-286 
    Details
    ISSN: 1573-5117
    Keywords: Sudan ; frontal bone ; age determination ; cyprinidae ; Jebel Aulia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In spite of the exuberance of recent approaches to age determination of fish, many ecologists are convinced that the most valid method is age reading from permanent marks or growth rings laid on skeletal parts. Of the known structures used, only the vertebrae are suitable and readable for a large variety of species and sizes. Examination of different skeletal structures of Labeo horie, a Cyprinid collected from Jebel Aulia reservoir, revealed that the frontal bone carried well-defined growth rings. The validity of these rings was checked against other direct and indirect methods of age determination. Results proved to be statistically valid, and the frontal bone offers an additional device of age determination of L. horie.
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    Seasonal abundance, breeding and sex-structure of populations of Tilapia nilotica (L.) and Labeo niloticus (F.) in the Jebel Aulia Dam area of the White Nile (1984)
    Springer
    Hydrobiologia 110 (1984), S. 287-294 
    Details
    ISSN: 1573-5117
    Keywords: Sudan ; abundance ; breeding ; sex-ration ; Tilapia ; Labeo ; White Nile
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Seasonal abundance, maturation and sex-structure were studied in populations of T. nilotica and L. niloticus in the Jebel Aulia reservoir and in the White Nile below the dam. L. niloticus showed a single annual breeding cycle from mid-July to December and was most abundant in October in the lake, and in early November in the river. T. nilotica showed two distinct annual seasons of abundance: summer (April to June) and autumn (November to October). Spawning activity was highest in summer (April to June) and autumn (late July to September). The sex-ratio varied inversely with age (size); males were predominant in populations of older fish, perhaps because of their greater endurance to adverse conditions as evidenced by their better survival in hypoxic water.
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    Fishes and fisheries of Lake Nubia, Sudan (1984)
    Springer
    Hydrobiologia 110 (1984), S. 305-314 
    Details
    ISSN: 1573-5117
    Keywords: Sudan ; fish species ; selectivity ; abundance ; distribution ; fish production
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Developing lake conditions in Lake Nubia were found to offer good commercial fisheries potential. This prospect initiated fishery research since 1967. In this study, 26 fish species belonging to 10 families were recorded. Compared with previous studies the total number has decreased and some of the species that were commercially important during the early years of the lake formation, are now negligible in occurrence (Distichodus, Citharinus, Bagrus). The species widely distributed in the lake are Labeo niloticus, Lates niloticus, Sarotherodon niloticus, Hydrocynus forskallii, Alestes baremose and Eutropius niloticus. Their highest production occurs during two periods: February to May and July to September. The dominant fish species feed on different items in a balanced equilibrium with the ecological and biological conditions.
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    Aspects of the biology of the catfish Clarias lazera (Cuv. & Val.) related to its economic cultivation (1984)
    Springer
    Hydrobiologia 110 (1984), S. 295-304 
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    ISSN: 1573-5117
    Keywords: Sudan ; Clarias ; breeding ; maturation ; hormones ; growth ; cultivation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The seasonal abundance, population structure, reproduction, feeding, respiratory adaptations and tolerance were studied in the catfish Clarias lazera (Cuv. & Val.) in the reservoir of Jebel Aulia on the White Nile, and in the Green-Belt canals near Khartoum. Continuous monitoring of the ripe, spent and spawning females and immature fish in the population revealed that C. lazera breed synchronously in the autumn in the reservoir and rather sporadically in the canals. Medium-sized females were more fecund than old and young females. Administration of pituitary extract enhanced maturation, induced spawning in mature fish, stimulated body growth, especially in maturing specimens, and produced, as a side-effect, a diuretic response. Mature fish depended on pulmonary respiration for about 45% of the total oxygen requirement. C. lazera fed preferentially on its fry and on decayed proteinaceous food. The suitability of this species for economic cultivation is discussed.
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    Gill net selectivity in Lake Nubia fisheries (1984)
    Springer
    Hydrobiologia 110 (1984), S. 315-317 
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    ISSN: 1573-5117
    Keywords: Sudan ; Lake Nubia ; fisheries
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The gill nets presently used in Lake Nubia fishing were subjected to a comparative study in regard to their relative efficiency. The results obtained indicate that Mesh 6 netted with Twine 4 is the most effective net, followed by Meshes 2, 4, 8 and 10 respectively. It has also been shown that, although individual nets undergo seasonal fluctuations in CUE, this does not, substantially affect their order of merit. The role of water characteristics on fish population distribution and subsequenct changes in the CUE was also noted.
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    Breeding of Barbus bynni (Pisces, Cyprinidae) in Jebel Aulia Reservoir, Sudan (1984)
    Springer
    Hydrobiologia 110 (1984), S. 319-325 
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    ISSN: 1573-5117
    Keywords: Sudan ; Pisces ; Cyprinidae ; Barbus bynni ; breeding ; Jebel Aulia Reservoir
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Barbus bynni begins to mature at Age IV. Ripening of gonads of mature fish starts in May when water temperature approaches the annual maximum. However, the spawning season coincides with the onset of the flood season in July. These facts, as well as the cyclic growth of the gonads, show that B. bynni spawns once a year. Fecundity varies with size of fish and gonads. However, this levels off in the middle size group. At this age the fecundity was estimated to be 1 424 693 eggs.
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    Food and feeding habits of Labeo niloticus (Pisces, Cyprinidae) in Jebel Aulia Reservoir, Sudan (1984)
    Springer
    Hydrobiologia 110 (1984), S. 327-332 
    Details
    ISSN: 1573-5117
    Keywords: Sudan ; Pisces ; Cyprinidae ; food and feeding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Basic knowledge on the feeding ecology of one of the common and commercially important fish species in Jebel Aulia Reservoir is provided. The structure of the feeding apparatus indicates that Labeo niloticus is a bottom feeder, depending on soft and decayed vegetation, organic debris and whatever small organisms found within. However, juveniles and fry are prone to explore all layers and depths of the river selectively for plankton. There is little evidence of seasonal selection of food. Changes in diet quality are governed by the availability of type of food. Variability of feeding activity is connected with climate and breeding season.
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    On the reliability of the growth rings in two species of the family Characidae in the Sudan (1984)
    Springer
    Hydrobiologia 110 (1984), S. 333-338 
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    ISSN: 1573-5117
    Keywords: Sudan ; fish ; Characidae ; growth of rings ; back-calculation ; aging structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The scales, opercula and vertebrae from 69 Hydrocyon forskali and 63 Alestes dentex were investigated for their reliability as aging structures. In both species the scales were unreliable due to their regenerative property, in spite of the clarity of their growth rings. Back-calculated lengths from the first growth ring laid on opercula and vertebrae resulted in values that coincided with the annual growth of the two species. In H. forskali, the mean back-calculated length from the two bones were 16.2 ± 5.9 and 16.8 ± 4.4 respectively, and for A. dentex, 11.1 ± 1.7 and 12.8 ± 1.8, respectively. Predictive equations for bone radius from fish length were written for both species. In this study, reliability was maximal between the observed and back-calculated lengths for both species (r 〉 0.95).
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    Development of dependence on aerial respiration in Polypterus senegalus (Cuvier) (1984)
    Springer
    Hydrobiologia 110 (1984), S. 351-363 
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    ISSN: 1573-5117
    Keywords: Sudan ; Polypterus ; aerial ; branchial ; respiration ; hypoxia ; hypercarbia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The respiratory behaviour and partitioning of O2 uptake between air and water were investigated in Polypterus genegalus using continuous-flow and two-phase respirometers and lung gas replacement techniques P. senegalus rarely resorts to aerial respiration under normal conditions. Partitioning of O2 consumption depends on the activity and age of fish and the availability of aquatic oxygen. Immature fish (12–22 g) cannot utilize aerial O2 but older fish exhibit age-dependent reliance on aerial respiration in hypoxic and hypercarbic waters. Pulmonary respiration accounts for 50% of the total requirement at aquatic O2 concentrations of about 3.5 mg · l−1 (or CO2 of about 5%) and fish rely exclusively on aerial respiration at O2 concentrations of less than 2.5 mg · l−1. Branchial respiration is initially stimulated by hypercarbia (CO2: 0.5–0.8%) but increased hypercarbia (CO2 − 1%) greatly depresses (by over 90%) brancial respiration and initiates (CO2: 0.5%) and sustains pulmonary respiration.
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    Adaptive respiratory significance of organophosphates (ATP & GTP) in air-breathing fishes (1984)
    Springer
    Hydrobiologia 110 (1984), S. 339-349 
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    ISSN: 1573-5117
    Keywords: Sudan ; Protopterus ; Polypterus ; Clarias ; ATP ; GTP ; development ; hypoxia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The ATP and GTP contents of erythrocytes of Protopterus annectens, Polypterus senegalus and Clarias lazera were assessed in relation to maturation and hypoxia. The steady state ‘normal’ concentrations of ATP were: 446, 316 and 475 µM/100 ml and those of GTP were 286, 93 and 85 µM/100 ml in Protopterus, Polypterus and Clarias, respectively. The level of ATP decreased and that of GTP increased with increments in body growth, especially during development of the pulmonary organs. The concentration of GTP also increased progressively with hypoxia (O2: 7.4 to 3.6 mg/l); the level ATP remained almost unaltered. The ratio of GTP increased markedly with increased hypoxia particularly in the adaptive respiratory range of aquatic oxygen concentrations (6.5–4.8 mg/l) when the fish were forced to depart from branchial respiration and became reliant on air-breathing.
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    The Nile: Description, hydrology, control and utilisation (1984)
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    Hydrobiologia 110 (1984), S. 1-13 
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    ISSN: 1573-5117
    Keywords: Sudan ; Nile ; hydrology ; control ; utilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Nile is a vital resource of north-eastern Africa. After a description of its basin, and its hydrology,the different phases in the process of man gaining control on the river are discussed. Presently, the Nile is used for irrigation, the generation of hydroelectric power, navigation, and, of particular importance to limnologists, fisheries. Future developments in the management of the Nile are summarized.
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    Implications of sea mining for the Red Sea environment (1984)
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    Hydrobiologia 110 (1984), S. 15-19 
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    ISSN: 1573-5117
    Keywords: Sudan ; RSC programme ; tailings ; impacts on environment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The unique Red Sea environment has up to now been relatively unaffected by polluting consequences of Man's activities, except for evidence of oil along the coasts and reefs from transiting ships, harbours, industrial and human wastes with growing population and industrialization. The discovery, in the mid-sixties, of deposits of metalliferous muds, rich in heavy metals, and the probable mining and processing of these was expected to add to the risk of pollution. The Saudi-Sudanese Red Sea Commission, entrusted with the development and exploration of these non-living resources, has already set out an environmental study programme, more or less directly related to the conservation of the living marine resources. Within this framework, the studies have focused on the assessment and magnitude of possible risks for the environment resulting from a tailings disposal in the Atlantis 11 Deep over an extended period of time, and on the development of methods to minimize these risks. The results obtained so far, indicate that a well-controlled tailings disposal below 1 000 metre water depth would keep the environmental impact of such an operation in acceptable dimensions. But it is hoped that the forthcoming Pilot Mining Operations will be capable of clarifying some uncertainties through further computer modelling, monitoring a full scale tailings disposal test, using realistic input conditions and evaluation of the ecosystem.
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    A faunistic reconnaissance of Lakes Kundi and Keilak, western Sudan (1984)
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    Hydrobiologia 110 (1984), S. 33-44 
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    ISSN: 1573-5117
    Keywords: Sudan ; lakes ; fauna ; distribution ; comparative survey
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Lakes Kundi and Keilak show large seasonal variations in area, but have permanent dry season residual areas rich in aquatic macrophytes. The faunas of the two lakes are similar, with L. Kundi (130 species recorded) being richer than L. Keilak (91 species). The fauna of L. Kundi includes the protomonad Rhipidodendron huxleyi, which has not been previously recorded in Africa. In L. Keilak we found Neozonocypris mirabilis, previously known only from L. Tanganika.
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    Physical and chemical characteristics of the Blue Nile and the White Nile at Khartoum (1984)
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    Hydrobiologia 110 (1984), S. 21-32 
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    ISSN: 1573-5117
    Keywords: Sudan ; Blue Nile ; chemical composition ; tropical rivers ; White Nile
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Fortnightly measurements of physical and chemical variables were made at two locations on the Blue and White Niles near Khartoum from August 1968 to December 1970. Variables analysed from each river were: temperature, pH, total residue, current velocity, oxygen, alkalinity, phosphate, nitrate, ammonia, silica, sulphate, iron, calcium, magnesium, sodium, potassium and oxidizable organic matter. The seasonal variations of these factors in the two Niles are compared and the interrelationships existing between some of them are discussed. Comparisons with earlier studies on the Nile and with some tropical rivers are made. In the Blue Nile, the amounts of suspended matter and nutrients are largely dependent upon the flood regime. Nitrate, phosphate, iron, oxidizable organic matter and total residue increase considerably in the Blue Nile when the river is in flood (peaks: 1 880 µg NO3-N l−1; 0.31 mg Fe l−1; 3 842 mg total residue · l−1). In the White Nile, concentrations of nitrate, phosphate, iron, oxidizable organic matter and total residue attain their peaks during the rainy season (270 µg NO3-N l−1; 163 tag PO4-P l−1; 0.46 mg Fe · l−1; 502 mg total residue · l−1). In both rivers, alkalinity, calcium, sodium and potassium tend to increase during the dry season while declining in the rainy season. Silica is depleted at certain times of the year, yet relatively high concentrations are maintained throughout the year and were not expected to limit growth of diatoms. Fall in silica concentrations, unlike nitrate, phosphate and iron, was always followed by a rapid restoration of a high level. Silica and magnesium showed no response to changes in discharge rates.
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    A quantitative study of the phytoplankton in the Blue and White Niles at Khartoum (1984)
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    Hydrobiologia 110 (1984), S. 47-55 
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    ISSN: 1573-5117
    Keywords: Sudan ; algae ; Blue Nile ; plankton ecology ; tropical rivers ; White Nile
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The variation in numbers of the major planktonic algae in the surface waters of the Blue Nile and White Nile were followed for 29 months (August 1968–December 1970). In terms of biomass, the phytoplankton was dominated by diatoms and blue-green algae; other groups were of minor importance. High phytoplankton densities occurred during winter in both rivers, and during summer in the Blue Nile, with values in the latter river greater than in the former. Melosira granulata and its variety angustissima and Anabaena flos-aquae var. intermedia f. spiroides were the most important taxa in the two Niles. Melosira distans and Attheya zachariasi, which are reported for the first time in the present study, preponderated at certain times in the Blue Nile. Microcystisflos-aqua which had been a minor component of the phytoplankton in both rivers during the early 1950s, showed a profuse growth in the Blue Nile. Lyngbya limnetica, Anabaenopsis cunningtonii and A. tanganyikae, which constituted important components of the phytoplankton in the early 1950s, either disappeared or maintained themselves in reduced numbers during the present study. This change in the algal flora of the two Niles may be attributed to the construction of the Roseres dam across the Blue Nile in 1966 and to the invasion of the White Nile by Eichhornia crassipes in 1957.
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    Permanent swamp vegetation of the Upper Nile (1984)
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    Hydrobiologia 110 (1984), S. 79-90 
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    ISSN: 1573-5117
    Keywords: Sudan ; swamp vegetation ; Sudd
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This paper describes vegetation in the nothern Sudd area of the Sudan. A visit by boat was made in April 1978 along the White Nile from Malakal to Lake No; to the inflow regions of the Bahr el Jebel, the Bahr el Zeraf and to the Bahr el Ghazal. Only the vegetation along the fringe of the rivers was observed as plants were tall and dense and it was not possible to penetrate into the inner swamps. The outer edge of the vegetation was fringed by extensive mats of free-floating Eichhornia crassipes which was easily dislodged and formed floating islands to be carried downstream. The main rivers, excluding the Bahr el Ghazal, were too deep and turbid to support beds of submerged species but plants such as Ceratophyllum demersum could be found amongst floating plants. Vossia cuspidata usually produced a broad zone to the landward of Eichhornia. It dominated the shallow water with a floating raft of stems growing out from the shore over the water surface. Massive stands of Cyperus papyrus and/or Phragmites karka, over 5 metres tall, dominated the vegetation behind and sometimes excluded the Vossia zone. The papyrus could form dense, floating rafts of rhizomes at the water's edge, but Phragmites always remained firmly rooted to the bottom. Floating papyrus and Vossia would become detached from the main beds and drifted downstream with Eichhornia. Creepers were common amongst papyrus but less common amongst Phragmites where the vegetation was generally more dense. Large stands of Typa domingensis were observed behind the fringe vegetation. The vegetation of the Bahr el Ghazal, in marked contrast to the rest, was stunted, and reasons for this are suggested. Species diversity was greater and the less turbid waters allowed considerable development of floating-leaved and submerged species. Estimates of fresh weights and heights of dominant vegetation types were attained but methods were very laborious and alternative ways have been suggested. The fresh weight of Eichhornia from a one metre square quadrat in the White Nile was around 70 kg. The shoots of Phragmites weighed 18.5 kg and Cyperus papyrus, 11.0 kg m−2.
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    Zooplankton associations in the swamps of southern Sudan (1984)
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    Hydrobiologia 113 (1984), S. 93-98 
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    ISSN: 1573-5117
    Keywords: tropical zooplankton ; swamps ; Sudan
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Samples from the main Nile channel yield a poor zooplankton, deficient in species and heavily laden with organic debris. Samples from side arms and floodplain lakes yield a richer zooplankton, often containing 15–20 species of rotifers and ten or more species of Crustacea. When the floodplain lakes are heavily vegetated the number of species increases. For the Crustacea the index of diversity (α) normally varies between 0.6 and 2.4, but in a side arm of the Bahr el Zeraf it reaches 6.1 and in Lake Ambadi on the Bahr el Ghazal it reaches 8.4. The diversity of the rotifers is somewhat higher, normally ranging between 2 and 4.5, but reaching 23 in Lake Ambadi. The zooplankton of Lake Ambadi is the most distinctive and contains several species not found at other stations. The reasons for the peculiar zooplankton of Lake Ambadi are discussed.
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    The effects of pH and aluminium toxicity on the growth and symbiotic development of cowpeas (Vigna unguiculata (L.) Walp) (1984)
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    Plant and soil 80 (1984), S. 423-430 
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    ISSN: 1573-5036
    Keywords: Acidity ; Aluminium ; Cowpea ; Nitrogen ; Rhizobium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The interaction of pH (4 or 6), aluminium (0 or 16 ppm at pH 4) and N source (symbiotic or combined) on the growth and nutrient status of cowpea (Vigna unguiculata) was studied in a glasshouse experiment. Low pH significantly decreased the growth of the plants dependent on symbiotic nitrogen fixation but at pH 4 the addition of 16 ppm Al further depressed growth in both nitrogen regimes. Al-ions appear to exert their effect primarily on the root system, as shown by the reduction in total length and fresh weight. The symbiotic development of the plants was affected by low pH but more markedly by the Al treatment. Shoot nitrogen concentrations were reduced from ca. 2.6% at pH 6 to 1.8% and 0.9% at pH 4 without and with aluminium respectively. Calcium concentration was decreased by low pH and further by Al in both nitrogen regimes. In all Al-treated plants, the aluminium was mainly accumulated in the roots and was associated with an increase in their phosphorus concentration.
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    Effects of nitrogen nutrition on xylem sap composition of Casuarinaceae (1984)
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    Plant and soil 81 (1984), S. 291-293 
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    ISSN: 1573-5036
    Keywords: Casuarinaceae ; Citrulline ; Frankia ; Nitrogen ; Nutrition ; Xylem sap
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The major nitrogenous compound in the xylem sap ofCasuarina equisetifolia is citrulline, irrespective of nitrogen nutrition (dinitrogen fixation, nitrate or ammonium). The detection of citrulline in non-nodulated Casuarina suggests that its formation is not confined to root nodules. This precludes the possibility of using the relative citrulline content of xylem sap for quantification of N2 fixation in Casuarina. The possibility exists, however, that the relative abundance of citrulline to other nitrogenous compounds (e.g. amides or nitrate) in the xylem sap could be used as an indicator of N2 fixation and should be evaluated further.
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    Effects of fertilization on the nutrient distribution of aboveground components ofAbies balsamea (L.) Mill (1984)
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    Plant and soil 80 (1984), S. 433-439 
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    ISSN: 1573-5036
    Keywords: Balsam fir ; Foliar analysis ; Lime ; Nitrogen ; Phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The following fertilizer treatments were applied to a 20-year-old aspen-birch-sprucefir stand in southeastern Maine: N at 448 kg/ha, P at 112 kg/ha, N and P applied as above in addition to 1751 kg/ha Ca and 27 kg/ha Mg. Five years after treatment, foliar concentrations of N, P and Ca for understory blasam fir exhibited significant increases in response to fertilization with those nutrients. Mean five-year height growth, adjusted for pretreatment differences, increased 36 percent in response to fertilization with N alone and in combination with P and lime.
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    Seasonal changes in foliar macronutrients (N, P, K, Ca and Mg) inEucalyptus saligna Sm. andE. wandoo Blakely growing in rehabilitated bauxite mine soils of the Darling Range, Western Australia (1984)
    Springer
    Plant and soil 81 (1984), S. 377-388 
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    ISSN: 1573-5036
    Keywords: Calcium ; Eucalyptus saligna ; Eucalyptus wandoo ; Foliar nutrients ; Magnesium ; Nitrogen ; Phosphorus ; Potassium ; Rehabilitation ; Seasonal trends
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Seasonal changes in the foliar concentration of macronutrients (N, P, K, Ca and Mg) in sapling trees ofEucalyptus saligna Sm. andE. wandoo Blakely growing in rehabilitated bauxite mined areas in the Darling Range of Western Australia are described. Foliar N concentration decreased with age of the fully expanded leaf tissue. Leaf N concentrations were also high when rates of litter decomposition were expected to be high during the period of early spring. The greatest foliar N difference between trees growing in good soil conditions and those from poorer soil conditions also occurred during this period. Levels of P in leaves were highest in young developing leaves but once the leaves reached full size, no seasonal trend in P concentration was observed. Foliar K was lower during the winter and probably related to the period of maximum leaching by precipitation. High foliar K during summer, however, could be related to the role of K in lowering cellular water potential. Leaf Ca was highest during early sping. Low mobility of cellular Ca during the cool portion of the year was indicated. Foliar Mg showed a weak pattern of decreasing concentration with leaf age. The best season for sampling for these broadleafed evergreen species to provide information on plant nutrient status appears to be in spring.
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    Effects of roots and litter on mineralization processes in forest soil (1984)
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    Plant and soil 80 (1984), S. 391-405 
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    ISSN: 1573-5036
    Keywords: Carbon ; Clear cutting ; Exponential decay ; Forest ; Litter ; Mineralization ; Nitrogen ; Podzol ; Respiration ; Rhizosphere Soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Leaf litter breakdown and fine root production, including exudation, are two major influences upon carbon and nitrogen mineralization rates in forest soil. Sieving and root removal experiments were used to examine their effects. Although carbon mineralization rates declined in smaller particle size fractions of forest litter, this trend largely disappeared when results were calculated on an ash-free basis. Nitrogen mineralization by contrast, was greatest in smaller fractions. Much of the variation in carbon mineralization rates appeared to be associated with fine roots. A rapid initial exponential decay phase noted in laboratory respiration studies was probably associated with disappearance of available carbon in the form of root exudates and/or the microorganisms dependent on them. Clear cutting caused a marked reduction in the size of available carbon pools, reflecting decreased root exudation and rhizosphere activity. A model of mineralization is proposed which represents the available and humified carbon pools.
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    Preliminary studies of the fertilizer capability of some novel high analysis multinutrient compounds (1984)
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    Nutrient cycling in agroecosystems 5 (1984), S. 245-257 
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    ISSN: 1573-0867
    Keywords: Adamantane-type compounds ; Fertilizer ; High analysis nutrient compounds ; Nitrogen ; Phosphorus ; Phytotoxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In a preliminary assessment of the fertilizer capability of three high analysis NP(S) compounds, their possible phytotoxic effects were investigated in solution culture tubes. One of the compounds was studied in more detail in pot experiments with sand and a red-brown earth soil. Two adamantane-type compounds (APA and APAS) were capable of supplying N and P to plants, but also showed toxicity effects. With APA, this effect appeared to be dissipated in soil but not in sand. The toxic effect was alleviated by addition of soluble P or soluble P + N. Some plants absorbed excessive amounts of P, probably not all in the form of orthophosphate.
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    Mineral nutrient demands of the water hyacinth (Eichhornia crassipes (Mart.) Solms) in the White Nile (1984)
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    Hydrobiologia 110 (1984), S. 99-108 
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    ISSN: 1573-5117
    Keywords: Sudan ; water hyacinth ; nutrients ; P, N, Fe ; growth ; White Nile
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The possibility that the stunted growth of the water hyacinth in Bahr el Ghazal river in Sudan is influenced by nutrient elements is considered. Greenhouse experiments were carried out to determine the effects of deficiency and mineral nutrient additions on the growth of this plant. The water hyacinth was found to grow at a wide range of nutrient levels. Maximum growth was recorded at 21 mg l−1 N, 62 mg l−1 P, and 0.60 mg l−1 Fe.
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    Observations on the effect of the weevils Neochetina eichhorniae Warner and Neochetina bruchi Hustache on the growth of water hyacinth (1984)
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    Hydrobiologia 110 (1984), S. 95-98 
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    ISSN: 1573-5117
    Keywords: Sudan ; water hyacinth ; biological control ; weevils
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Water hyacinth Eichhornia crassipes (Mart.) Solms. is an aquatic weed that infests most of the White Nile system in the Sudan. Serious economical and ecological problems are caused by this weed. The two weevils Neochetina eichhorniae and Neochetina bruchi were imported and released in an attempted biological control against the weed. The adults of these weevils attack the plant and feed by removing tissues from the leaf pseudolamina and petioles. The larvae tunnel inside the petioles and the crown. The optimum temperature for feeding and development of both species is 25° C. Results obtained from stocking hyacinth plants with adults and larvae of both species separately revealed that N. bruchi is more efficient in checking the growth of the plant. The progeny of a pair of N. bruchi and N. eichhorniae reared separately on 41 hyacinth plants for a period of 61 days (one generation period) reduced their population growth by 25.4% and 12.7% respectively. The progeny of both species in a mixed culture reduced the growth of the plants by 22.5% in the same period, while in the control the population of the plants increased 136.6%.
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    A review of the rotifer fauna of the Sudan (1984)
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    Hydrobiologia 110 (1984), S. 113-130 
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    ISSN: 1573-5117
    Keywords: Sudan ; rotifers ; taxonomy ; biogeography ; Africa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A collection of rotifers contained in samples from the Blue, White and joint Niles in the Sudan, the Red Sea Hills, and Jebel Marra mountains is studied, and the previous literature on the rotifera of Sudan is reviewed. A total of 145 rotifer taxa are now known from this country. Ecological and distributional notes on selected species are added. Besides cosmopolitan, pantropical, and tropical species, a small but significant fraction of the fauna is of northern origin, possibly reflecting climatic conditions of the late-Pleistocene.
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    Bogidiella nubica n. sp. from interstitial waters of the Sudan (Crustacea: Amphipoda) (1984)
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    Hydrobiologia 110 (1984), S. 131-134 
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    ISSN: 1573-5117
    Keywords: Sudan ; amphipoda ; Bogidiellidae ; systematic ; ground water fauna
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Description of Bogidiella nubica, from interstitial waters in the Sudan. It is the first Bogidiella species known for the African continent, except for the Mediterranean area.
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    The occurrence of Limnohalacarus (Acari: Halacaridae) in Lake No, White Nile (1984)
    Springer
    Hydrobiologia 110 (1984), S. 135-136 
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    ISSN: 1573-5117
    Keywords: Sudan ; Nile ; Acari ; Halacaridae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Limnohalacarus africanus and L. fontinalis are recorded from Lake No. These are respectively the third and second records of these species, and represent considerable extensions of their known ranges.
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    Cladocera from the Sudan: Red Sea Hills, Jebel Marra and valley of the main Nile (1984)
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    Hydrobiologia 110 (1984), S. 163-169 
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    ISSN: 1573-5117
    Keywords: Sudan ; Cladocera ; biogeography ; taxonomy ; Sudan ; Nile
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Twenty species of Cladocera are reported from the Nile, where lacustrine species dominate, and from Jebel Marra and the Red Sea Hills, where chydorids dominate. The community found in the Red Sea Hills is more typically desertic than that of Jebel Marra, which appears closely related to the fauna of the West and Central African Sahel.
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    Nilobathynella predynastica n.g., n.sp. (Crustacea:Bathynellacea) from the Nile valley in Nubia (1984)
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    Hydrobiologia 110 (1984), S. 171-175 
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    ISSN: 1573-5117
    Keywords: Sudan ; Crustacea ; Bathynellacea ; Nile
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Nilobathynella predynastica n.g., n.sp. from Abri, Nubia, is the first representative of the Tribus Cteniobathynellini in the Nile Valley. Its relationship with the other Cteniobathynellini, as well as its biogeographical significance, are briefly discussed.
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    On the freshwater ostracods (Crustacea, Ostracoda) of the Sudan, with special reference to the Red Sea Hills, including a description of a new species (1984)
    Springer
    Hydrobiologia 110 (1984), S. 137-161 
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    ISSN: 1573-5117
    Keywords: Sudan ; freshwater ostracods ; Africa ; taxonomy ; zoogeography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A collection of freshwater ostracods from the Sudan is studied and 18 species are recorded. Paracypretta amati sp.n. is new to science. A redescription of the holotype female of Paracypretta aratra (Brady, 1904) (not recorded in this collection) and a provisional key to the species of Paracypretta are given. Heterocypris giesbrechtii (G. W. Müller, 1898) is re-described; Heterocypris sobrinus (Masi, 1932) is placed in the synonymy of H. fretensis; Hemicypris intermedia (Lindroth, 1953) is recorded for the first time since its original description and is redescribed, while Cyprinotus largereticulatus Rome, 1969 is transferred to Hemicypris. The zoogeographical composition of this fauna is briefly discussed.
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    URL: http://dx.doi.org/10.1007/BF00025786
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    Parapseudoleptomesochra attirei n.sp., a new species of Nitocrella from Nubia (Copepoda, Harpacticoida) (1984)
    Springer
    Hydrobiologia 110 (1984), S. 177-180 
    Details
    ISSN: 1573-5117
    Keywords: Sudan ; Nubia ; groundwater ; Copepoda ; Nitocrella
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Description of Parapseudoleptomesochra attirei from a well in a dry wadi bed at At Tire, Nubia. Its closest relative is found in a semidesert area in Iran. The chorological implications of this finding are briefly discussed.
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    URL: http://dx.doi.org/10.1007/BF00025789
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    Dragonflies (Insecta, Odonata) from the Red Sea Hills and the main Nile in Sudan (1984)
    Springer
    Hydrobiologia 110 (1984), S. 181-190 
    Details
    ISSN: 1573-5117
    Keywords: Sudan ; Odonata ; Nile ; Red Sea Hills ; biogeography ; deserts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Twenty-one species of dragonflies are recorded from the Nile and the Red Sea Hills in the Sudan. The majority are species of africotropical origin, but wide-ranging and tolerant of strongly fluctuating environmental conditions. A small but significant fraction is restricted to the Nile Valley, and another fraction, found only in the Red Sea Hills, is composed of Eremian species of Palaearctic origin. Besides adults, the last-instar larvae of Pseudogrion niloticum and of Paragomphus pumilio are described and figured.
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    URL: http://dx.doi.org/10.1007/BF00025790
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    The calanoid copepods of the Nile system (1984)
    Springer
    Hydrobiologia 110 (1984), S. 191-212 
    Details
    ISSN: 1573-5117
    Keywords: Sudan ; Copepoda ; Calanoida ; taxonomy ; biogeography ; Africa ; Nile
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract At least 11 or 12 calanoid taxa occur in the Nile system. One species is typical of the river and of Lake Chad (Th. galebi); two are restricted to Lake Victoria (Th. galeboides, T. stuhlmanni), but both might be only subspecies to more widespread species. One is restricted to Lakes Edward and George (T. worthingtoni) but is a little known species. No calanoids are on record from Lakes Albert and Kyoga, while the species reported from Lake Turkana (T. banforanus) is out of range, and almost certainly represents an erroneous record. Among the remaining species, four are East-African, ranging from the southern tip of the continent to the Ethiopian plateau and the Nile valley (P. schultzei, Th. mixtus, T. kraepelini, T. cf orientalis), while two are Sahelian species that span Africa from east to west (M. mauretanicus, T. processifer et ssp.). Two new synonyms are introduced. One new subspecies (T. processifier friedae) is described from the Ethiopian plateau. It is suggested that Tropodiaptomus orientalis (Brady, 1886), the type species of its genus, should not be considered a nomen dubium, but should be redescribed on its type female(s) and on topotypical males from Sri Lanka.
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    URL: http://dx.doi.org/10.1007/BF00025791
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    Ring formation and annual growth in Corbicula consobrina Caillaud, 1827 (Bivalvia, Corbiculidae) (1984)
    Springer
    Hydrobiologia 110 (1984), S. 219-225 
    Details
    ISSN: 1573-5117
    Keywords: Sudan ; Bivalvia ; Corbicula ; ring formation ; White Nile
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The growth of C. consobrina of the White Nile near Khartoum was studied during March–December, 1977 from material collected from fish guts every two months. It was found that the growth season extends from February to July in correlation with the rise in temperature. Food was abundant and the concentration of the dissolved calcium in the river water was also increasing. During the flood season from July to October, the clams entered a resting state as a result of the annual siltation and consequently growth was arrested. Growth rings were found to be formed as a result of the siltation-induced resting state. There is evidence that little growth occurred during the cooler months from October to December. The development of the false rings on the shells is possibly a result of the changes in the water levels. Analysis of the growth of the adult clams showed that there is a clear size-time relation; there was close agreement between the calculated maximum sizes and the actual data collected from the field. Other examples from Sudanese inland waters were also discussed. The role of the annual hydrological cycles in regulating the populations activities and hence the growth of the individuals was found to be important.
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    URL: http://dx.doi.org/10.1007/BF00025793
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    Prevalence of nitrous oxide reducing capacity in denitrifiers from a variety of habitats (1984)
    Springer
    Plant and soil 81 (1984), S. 421-428 
    Details
    ISSN: 1573-5036
    Keywords: Acetylene inhibition ; Denitrifiers ; Electron acceptor ; Incubation ; Nitrate ; Nitrous oxide ; Nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A total of 81 strains isolated by T. N. Gamble from soils from eight countries, fresh water lake sediments and nitrified poultry manure were examined for their ability to grow on N2O as their electron acceptor, as well as for their tendency to produce N2O from NO 3 − in the absence and presence of acetylene. Seventy-seven of the 81 strains were confirmed as denitrifiers. Fifty-nine of the 77 strains grew on N2O, while 12 strains produced N2O but could not utilize it. Six strains reduced NO 3 − to N2 but could not grow on N2O, suggesting that even if N2O is always an intermediate product of denitrification, it is not always a freely diffusible intermediate. The organisms, however, would consume N2O that accumulated early in growth and accumulated N2O in the presence of acetylene. Thus the total number of N2O users was 65 strains or 83% of the total tested. This implies that the N2O reducing capacity of denitrifiers occur widely in nature. A high proportion ofPseudomonas fluorescens biotype II reduced N2O. The accumulation of N2O from NO 3 − in the presence of acetylene provides strong evidence that N2O is generally an intermediate in denitrification as well as provides additional support for the usefulness of this chemical as a general inhibitor of N2O reduction.
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    URL: http://dx.doi.org/10.1007/BF02323056
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    Fertilization of orange trees with sulfur-coated urea. Nitrogen levels in leaves and fruits (1984)
    Springer
    Plant and soil 80 (1984), S. 247-254 
    Details
    ISSN: 1573-5036
    Keywords: Citrus ; Controlled-release fertilizers ; Nitrogen ; Nutrition ; Sulfur-coated urea ; Ammonium nitrosulphate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The effect of one application of the slow-release fertilizer, sulfur-coated urea, on the nitrogen level in leaves, fruit and bark of Washington Navel orange trees was studied during the different periods of the annual vegetative cycle, in comparison with two annual applications of the fertilizer ammonium nitrosulphate. Results indicate that a single spring application of 750 g nitrogen per tree maintains N levels in old leaves, spring shoots, ovaries, fruit and bark statistically equal to those obtained using double doses of ANS in two applications.
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    URL: http://dx.doi.org/10.1007/BF02161180
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    Foliar and twig macronutrients (N, P, K, Ca and Mg) in selected species ofEucalyptus used in rehabilitation: sources of variation (1984)
    Springer
    Plant and soil 81 (1984), S. 363-376 
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    ISSN: 1573-5036
    Keywords: Branch nutrients ; Calcium ; Eucalyptus saligna ; Eucalyptus wandoo ; Foliar nutrients ; Magnesium ; Nitrogen ; Phosphorus ; Potassium ; Rehabilitation ; Soil nutrients
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The macronutrient variation within four 6 year oldEucalyptus saligna and four 5 year oldE. wandoo growing on rehabilitated bauxite pits was determined. Significant differences in mean nutrient concentrations were generally recorded between good soil condition sites and poor soil sites, between tree individuals, branch height, and plant organ type; but mean nutrient values were not different among canopy aspects. Fully expanded leaves of the current year provided the most uniform nutrient levels among the plant organs and showed major differences between sites with good soil nutrient conditions and those with poor conditions. Differences in foliar and branch levels of N, P, K, Ca and Mg, the variation between sites, canopy heights and plant organ types, and the use of foliar nutrient levels to indicate deficiencies are discussed.
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    URL: http://dx.doi.org/10.1007/BF02323051
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    Changes in biochemical composition and energy utilization during metamorphosis of leptocephalous larvae of the bonefish (Albula) (1984)
    Springer
    Environmental biology of fishes 10 (1984), S. 243-251 
    Details
    ISSN: 1573-5133
    Keywords: Lipid ; Protein ; Carbohydrate ; Nitrogen ; Ash ; Caloric content ; Larval development ; Nutrition ; Elopiformes ; Albulidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis Energy use and changes in whole-body content of lipid, protein, nitrogen, carbohydrate and ash were followed during metamorphosis of leptocephalous larvae of the bonefish (Albula). During metamorphosis, which requires about 8–12 days, larvae lost about 3–4 mg of lipid, or about 50% of the total lipid content. Lipid levels, calculated on a dry weight basis, showed no discernible trends, with values ranging from 138–185 mg (g dry wt)−1. Protein content was 8.4 mg per larva and showed no significant change. However, protein levels increased from 147 to 329 mg (g dry wt)−1. Nitrogen content decreased slightly from about 3.5 to 3.2 mg per larva. A comparison of protein and nitrogen values, expressed as % dry weight, showed that, in larvae which were just beginning to metamorphose, 70% of the total nitrogen was non-protein nitrogen (NPN). The NPN decreased to 58% of the total nitrogen towards the end of metamorphosis. Carbohydrate content fell from about 3.5 to 0.6 mg per larva, which represents an 83% loss. Carbohydrate levels also fell from about 81 to 32 mg (g dry wt)−1. In addition, most of the carbohydrate appears to be bound to protein. Ash content decreased by 52%, from 4.6 to 2.2 mg per larva. Caloric content fell slightly from about 182 to 141 calories per larva whereas caloric density showed no discernible trends, with values ranging from 4.180 to 4.725 kcal (g dry wt)−1. These results indicate that metamorphosing leptocephali, which apparently do not feed, probably derive most of their energy requirements from metabolizing endogenous lipid and carbohydrate stores formed during the premetamorphic interval.
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    URL: http://dx.doi.org/10.1007/BF00001477
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