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  • 1
    Electronic Resource
    Electronic Resource
    Trophic interactions in soils as they affect energy and nutrient dynamics. V. Phosphorus transformations (1977)
    Springer
    Microbial ecology 4 (1977), S. 381-387 
    Details
    ISSN: 1432-184X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Regeneration of nutrients from relatively nutrient-poor organic residues is essential for overall operation of an ecosystem. Nutrients thus released are, however, inadequate for the needs of the decomposer populations, and a much faster nutrient turnover involving bacterial immobilization and release occurs concurrently. Evidence from aquatic ecosystems indicates that bacteria release little phosphorus, for which they have high demand, whereas bacterial grazers play an important role in regeneration of bacterial phosphorus. Our studies extend these relationships to terrestrial ecosystems. We studied phosphorus immobilization and mineralization in soil incubations, simulating rhizospheres with combinations of bacterial, amoebal, and nematode populations. Bacteria quickly assimilated and retained much of the labile inorganic phosphorus as carbon substrates were metabolized. Most of this bacterial phosphorus was mineralized and returned to the inorganic phosphorus pool by the amoebae. Nematode effects on phosphorus mineralization were small, except for indirect effects on amoebal activity. The observed remineralization may reflect direct excretion by the amoebae, physiological effects on the bacterial populations, or both. These results suggest a major role of microfauna in nutrient cycling.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02013281
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  • 2
    Electronic Resource
    Electronic Resource
    Trophic interactions in soils as they affect energy and nutrient dynamics. III. Biotic interactions of bacteria, amoebae, and nematodes (1977)
    Springer
    Microbial ecology 4 (1977), S. 361-371 
    Details
    ISSN: 1432-184X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Bacteria (Pseudomonas), amoebae (Acanthamoeba), and nematodes (Mesodiplogaster) were raised in soil microcosms with and without glucose additions. Nematode and amoebal grazing on bacteria significantly reduced bacterial populations by the end of a 24-day incubation period. Amoebal numbers decreased in the presence of nematodes with a corresponding increase in nematode numbers which reached a maximum of 230 nematodes/g of soil in the treatment with amoebae and glucose additions. After 24 days the nematode populations in the treatments without carbon additions were dominated by resistant dauer larvae indicating the unavailability of food. Although larval numbers were high in the treatments with glucose additions, the adult component of the population was still increasing at the end of the 24-day experiment. The effect of the presence of amoebae on nematode abundance was of the same magnitude as addition of 600Μg glucose-C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02013279
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  • 3
    Electronic Resource
    Electronic Resource
    Trophic interactions in soils as they affect energy and nutrient dynamics. IV. Flows of metabolic and biomass carbon (1977)
    Springer
    Microbial ecology 4 (1977), S. 373-380 
    Details
    ISSN: 1432-184X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Flows of biomass and respiratory carbon were studied in a series of propylene-oxide sterilized soil microcosms. One-half of the microcosms received three pulsed additions of 200 ppm glucose-carbon to mimic rhizosphere carbon inputs. Biotic variables were: bacteria (Pseudomonas) alone, or amoebae (Acanthamoeba) and nematodes (Mesodiplogaster) singly, or both combined in the presence of bacteria. Over the 24-day experiment, respiration was significantly higher in the microcosms containing the bacterial grazers. Biomass accumulation by amoebae was significantly higher than that by nematodes. The nematodes respired up to 30-fold more CO2 per unit biomass than did amoebae. Similar amounts of carbon flowed into both respiratory and biomass carbon in microcosms with fauna, compared with the bacteria-alone microcosms. However, partitioning of available carbon by the microfauna varied considerably, with little biomass production and relatively more CO2-C produced in the nematode-containing microcosms. The amoebae, in contrast, allocated more carbon to tissue production (about 40% assimilation efficiency) and correspondingly less to CO2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02013280
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  • 4
    Electronic Resource
    Electronic Resource
    Trophic interactions in soils as they affect energy and nutrient dynamics. I. Introduction (1977)
    Springer
    Microbial ecology 4 (1977), S. 345-349 
    Details
    ISSN: 1432-184X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The dynamics of nutrient transformations at the soil-root interface are complex but amenable to controlled experimental study. Using a conceptual model we introduce a series of papers which ascertain the role of microfloral-faunal trophic interactions in carbon, nitrogen, and phosphorus transformations in soil microcosms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02013277
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  • 5
    Electronic Resource
    Electronic Resource
    Effects of streptomycin, cycloheximide, Fungizone, captan, carbofuran, cygon, and PCNB on soil microorganisms (1984)
    Springer
    Microbial ecology 10 (1984), S. 345-358 
    Details
    ISSN: 1432-184X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Eight biocides were chosen to determine whether they had any effects on nontarget organisms in soil and to what extent they would reduce their target populations under laboratory experimental conditions. A simplified microcosm system was utilized in which reduced species arrays that included field populations of either only bacteria and fungi, or bacteria, fungi, and protozoa (no nematodes, arthropods, or plants) were inoculated into sterilized soil. In a second set of experiments, plants were grown in sterilized soil. A bactericide-streptomycin-four fungicides-cycloheximide, Fungizone (amphotericin B), captan, and PCNB (quintozene)-an acaricide-cygon-an insecticide-nematicide-carbofuran-and an insecticide-diazinon-were used. Each biocide had effects on nontarget organisms although the increases or decreases, with respect to the control, were of only limited duration. Reductions in target groups were typically of longer duration. Streptomycin, applied at 1 mg·g−1 soil, did not decrease bacterial populations during the experimental incubation. At 3 mg·g−1 soil, streptomycin decreased the numbers of bacteria that grew on tryptone agar, but also reduced active hyphae. Fungizone was the most effective of the 4 fungicides tested in reducing active hyphae. Increased bacterial populations were usually observed following fungal reductions. Carbofuran had the fewest effects on the test organisms (bacteria, fungi, and protozoa). Only an initial stimulation of bacterial and fungal populations was observed with cygon although it also increased NH4 +-N concentrations in soil during most of the incubation, as did streptomycin and cycloheximide. A transitory increase in fungal populations following a decrease in ciliate numbers was observed in the cygon with grazers treatments. Diazinon reduced all microbial populations and inorganic nitrogen concentrations measured. Cygon and PCNB decreased growth of blue grama plants, while streptomycin reduced shoot weights of blue grama. These results should be useful in assessing the effects of these biocides when applied to more complex systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02015559
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  • 6
    Electronic Resource
    Electronic Resource
    A simulation model for the effect of predation on bacteria in continuous culture (1977)
    Springer
    Microbial ecology 3 (1977), S. 259-278 
    Details
    ISSN: 1432-184X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A simulation model was developed for the carbon (C), nitrogen (N), and phosphorus (P) content of bacteria and their medium in a chemostat. Cell components distinguished included the structural component, synthetic machinery, building blocks and intermediates, C reserves, ammonium (NH4), orthophosphate (PO4), and polyphosphate. Growth, incorporation of substrates, and production of waste products were related to physiological status, as indicated by the amounts of various cell components. The model was fitted to data from chemostats on the chemical composition of bacteria growing in C-, N-, and P-limiting media and was used to explore the consequences of predation on bacterial populations. In C-limiting media predation (without the return of nutrients to the medium by the predator) increased NH4 uptake in spite of a decrease in bacterial biomass. In N-limiting media predation decreased both biomass and the rate of N uptake. These results were accounted for by the effect of growth rate on bacterial N demand. In C-limiting media the return of NH4 and PO4 by the predator did not change the effect of predation on bacteria. But in N-limiting media the return of nutrients decreased the effect of predation on biomass, and stimulated respiration and NH4 uptake by the bacteria. The effect of growth rate on the chemical composition of bacteria was proposed as a possible explanation of the stimulatory effect of predators on bacteria.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02010735
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  • 7
    Electronic Resource
    Electronic Resource
    A chemistry home page on the World Wide Web (1997)
    Springer
    Fresenius' journal of analytical chemistry 357 (1997), S. 209-213 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract In this article a brief overview of the World Wide Web (WWW) is given, with some examples of the kind of information and services pertaining to analytical chemistry that can be found there. An existing WWW site that has been set up for analytical chemists is used as a case in point. The article concludes with a brief look at some of the issues raised by publishing on the Internet.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160050140
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  • 8
    Electronic Resource
    Electronic Resource
    Nitrogen availability to grain sorghum from organic and inorganic sources on sandy and clayey soil surfaces in a greenhouse pot study (1996)
    Springer
    Biology and fertility of soils 21 (1996), S. 271-276 
    Details
    ISSN: 1432-0789
    Keywords: 15N transformations ; Crop residues ; Soil texture ; Soil aggregation ; Microbial pool ; Microbial biomass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In a greenhouse pot study, we examined the availability of N to grain sorghum from organic and inorganic N sources. The treatments were15N-labeled clover residues, wheat residues, and fertilizer placed on a sandy clay loam and loamy sand soil surface for an 8-week period. Soil aggregates formed under each soil texture were measured after 8 weeks for each treatment. Significantly greater 15N was taken up and recovered by grain sorghum in sandy clay loam pots compared with loamy sand pots. Greater 15N recovery was consistently observed with the inorganic source than the organic sources regardless of soil texture or time. Microbial biomass C and N were significantly greater for sandy clay loam soil compared with the loamy sand. Microbial biomass 15N was also significantly greater in the sandy clay loam treatment compared to the loamy sand. The fertilizer treatment initially had the greatest pool of microbial biomass 15N but decreased with time. The crop residue treatments generally had less microbial biomass 15N with time. The crop residues and soil texture had a significant effect on the water-stable aggregates formed after 8 weeks of treatments. Significantly greater water-stable aggregates were formed in the sandy clay loam than the loamy sand. Approximately 20% greater water-stable aggregates were formed under the crop residue treatments compared to the fertilizer only treatment. Soil texture seemed to be one of the most important factors affecting the availability of N from organic or inorganic N sources in these soils.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00334903
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  • 9
    Electronic Resource
    Electronic Resource
    Earthworms and enchytraeids in conventional and no-tillage agroecosystems: A biocide approach to assess their role in organic matter breakdown (1990)
    Springer
    Biology and fertility of soils 10 (1990), S. 1-10 
    Details
    ISSN: 1432-0789
    Keywords: Earthworm ; Enchytraeid ; Tillage ; Organic matter ; Biocide ; Agroecosystems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Earthworm and enchytraeid densities and biomass were sampled over an 18-month period in conventional and no-tillage agroecosystems. Overall, earthworm densities and biomass in the no-till system were 70% greater than under conventional tilling, and enchytraeid densities and biomass in the no-till system were 50%–60% greater. To assess the role of annelids in the breakdown of soil organic matter, carbofuran was applied to field enclosures and target (earthworm and enchytraeid biomass, standing stocks of organic matter) and non-target effects (bacteria, fungi, protozoa, nematode and microarthropod densities, litter decay rates, plant biomass) were determined in two 10-month studies. In the winter-fall study, carbofuran reduced the annelid biomass, and total soil organic matter standing stocks were 47% greater under no-till with carbofuran compared to control enclosures. Twelve percent of the difference could have been due to non-target effects of carbofuran, as determined from litterbag decay rates. In the summer-spring study, carbofuran again significantly reduced the annelid biomass, and treated pens in the no-till area had significantly greater standing stocks of fine organic matter (43%–45%). Although the densities of bacteria and nematodes were reduced in carbofuran-treated litterbags under a no-till system, the rates of decay were not reduced and estimates of the amount of organic matter processed could not be adjusted for non-target effects. A 76% difference in the standing stock of coarse organic matter between control and carbofuran-treated pens in the conventional-till system indicated further non-target effects. We concluded that our estimates of the amount of organic matter processed by annelids in no-till and conventionally tilled agroecosystems represented a maximum potential because of the confounding non-target effects of carbofuran.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00336117
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  • 10
    Electronic Resource
    Electronic Resource
    Soil biology, soil ecology, and global change (1992)
    Springer
    Biology and fertility of soils 14 (1992), S. 104-111 
    Details
    ISSN: 1432-0789
    Keywords: Global change ; Scaling ; Hierarchies ; Soil organisms ; Soil processes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary This overview paper addresses aspects of scaling in space and time, and scaling in relation to micro-and macrohabitats. Ecological processes in soils are examined for possible generalizations about processes and organisms, across a wide range of different habitats. Problems of scaling in space and time that have an important impact on processes associated with global change are outlined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00336258
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