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  • 1
    Electronic Resource
    Electronic Resource
    Abundance of soil mites under four agroforestry tree species with contrasting litter quality (1999)
    Springer
    Biology and fertility of soils 30 (1999), S. 107-112 
    Details
    ISSN: 1432-0789
    Keywords: Key words Density ; Diversity ; Soil mites ; Agroforestry ; Community structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  Populations of soil-dwelling mites were monitored in monoculture plots of four agroforestry tree species, Gliricidia sepium, Leucaena leucocephala, Dactyladenia barteri and Treculia africana, and compared to those in grass and secondary forest plots in the dry season (December 1993 to January 1994) and in the wet season (April to June 1994) in southwest Nigeria. Mite populations were very low in all plots during the dry season (500–3000 m–2), compared to those during the wet season (10 000–30 000 m–2). The highest mite population was observed in Gliricidia plots (3 044 m–2) for the dry season and Leucaena plots (30 240 m–2) for the wet season. Mite genera that were dominant in all the experimental plots were Annectacarus, Haplozetes, Machadobelba, Scheloribates and members of the Galumnidae, Dermanyssidae and Parasitidae. The community structure of mites was similar in the soil for Treculia and Gliricidia plots and for Leucaena and Dactyladenia plots. There were more taxonomic groups of mites under Leucaena than in the other agroforestry plots. Based on the density, diversity and complexity of the mite communities, Leucaena was considered to be better than other agroforestry species in encouraging the growth of mite populations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740050595
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  • 2
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    Abundance of soil mites under four agroforestry tree species with contrasting litter quality (1999)
    Springer
    Details
    Publication Date: 1999-11-11
    Print ISSN: 0178-2762
    Electronic ISSN: 1432-0789
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Springer
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    PAPER CURRENT
  • 3
    Electronic Resource
    Electronic Resource
    Agricultural soils as a sink to mitigate CO2 emissions (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Soil use and management 13 (1997), S. 0 
    Details
    ISSN: 1475-2743
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract. Agricultural soils, having been depleted of much of their native carbon stocks, have a significant CO2 sink capacity. Global estimates of this sink capacity are in the order of 20-30 Pg C over the next 50-100 years. Management practices to build up soil C must increase the input of organic matter to soil and/or decrease soil organic matter decomposition rates. The most appropriate management practices to increase soil C vary regionally, dependent on both environmental and socioeconomic factors.In temperate regions, key strategies involve increasing cropping frequency and reducing bare fallow, increasing the use of perennial forages (including N-fixing species) in crop rotations, retaining crop residues and reducing or eliminating tillage (i.e. no-till). In North America and Europe, conversion of marginal arable land to permanent perennial vegetation, to protect fragile soils and landscapes and/or reduce agricultural surpluses, provides additional opportunities for C sequestration.In the tropics, increasing C inputs to soil through improving the fertility and productivity of cropland and pastures is essential. In extensive systems with vegetated fallow periods (e.g. shifting cultivation), planted fallows and cover crops can increase C levels over the cropping cycle. Use of no-till, green manures and agroforestry are other beneficial practices. Overall, improving the productivity and sustainability of existing agricultural lands is crucial to help reduce the rate of new land clearing, from which large amounts of CO2 from biomass and soil are emitted to the atmosphere.Some regional analyses of soil C sequestration and sequestration potential have been performed, mainly for temperate industrialized countries. More are needed, especially for the tropics, to capture region-specific interactions between climate, soil and management resources that are lost in global level assessments.By itself, C sequestration in agricultural soils can make only modest contributions (e.g. 3-6% of total fossil C emissions) to mitigating greenhouse gas emissions. However, effective mitigation policies will not be based on any single ‘magic bullet’ solutions, but rather on many modest reductions which are economically efficient and which confer additional benefits to society. In this context, soil C sequestration is a significant mitigation option. Additional advantages of pursuing strategies to increase soil C are the added benefits of improved soil quality for improving agricultural productivity and sustainability.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1475-2743.1997.tb00594.x
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  • 4
    Electronic Resource
    Electronic Resource
    A class of constraint qualifications in nonsmooth optimization (1999)
    Springer
    Annals of operations research 87 (1999), S. 383-391 
    Details
    ISSN: 1572-9338
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Notes: Abstract In this paper, we give a generalized Abadie constraint qualification (CQ) for a class of nonsmooth vector‐valued optimization. Under this CQ, we obtained the Kuhn‐Tucker‐typeoptimality condition where the multipliers associated with the objective functions are all positive.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018953607589
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  • 5
    Electronic Resource
    Electronic Resource
    Compactification of moduli space of harmonic mappings (1999)
    Springer
    Commentarii mathematici Helvetici 74 (1999), S. 201-237 
    Details
    ISSN: 1420-8946
    Keywords: Keywords. Compactness, harmonic maps, stratified Riemann surface.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract. We introduce the notion of harmonic nodal maps from the stratified Riemann surfaces into any compact Riemannian manifolds and prove that the space of the energy minimizing nodal maps is sequentially compact. We also give an existence result for the energy minimizing nodal maps. As an application, we obtain a general existence theorem for minimal surfaces with arbitrary genus in any compact Riemannian manifolds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s000140050086
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  • 6
    Electronic Resource
    Electronic Resource
    The inhomogeneity of two-wave coupling in photorefractive crystals in 90° geometry (1996)
    Springer
    Applied physics 63 (1996), S. 35-38 
    Details
    ISSN: 1432-0649
    Keywords: 42.65.Hw
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We derived the coupling equations of two-wave coupling in photorefractive crystals in 90° geometry where pump and signal beams enter two mutually orthogonal crystal faces vertically. We solved the equations numerically in the case of non-local response and illustrated the influence of the coupling coefficientΓ, the absorption coefficient α and the ratio of intensities of the two incident beams,R, on the inhomogeneity of transmitted pump and signal beams.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01112834
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  • 7
    Electronic Resource
    Electronic Resource
    Nodulation and estimation of symbiotic nitrogen fixation by herbaceous and shrub legumes in Guinea savanna in Nigeria (1996)
    Springer
    Biology and fertility of soils 23 (1996), S. 441-448 
    Details
    ISSN: 1432-0789
    Keywords: Bradyrhizobium spp. ; Effectiveness ; Guinea savanna ; Isolation ; N fertilizer ; Soil origin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Twelve herbaceous and shrub legume species were grown in pot and field experiments in five sites representing three agroecological zones in moist savanna in Nigeria. The objectives were to: (1) assess natural nodulation of the legumes and characterize their indigenous rhizobia, (2) determine their need for rhizobia inoculation and (3) estimate the amount of N2 fixed by each of these legumes. At 4 weeks after planting (WAP), Crotolaria verrucosa was not nodulated at any of the sites while Centrosema pascuorum had the highest number of nodules in all sites. At 8 WAP, all legumes were nodulated, with Mucuna pruriens having the least number of nodules and Stylosanthes hamata the highest. The number of nodules, however, was inversely correlated to the mass of nodules. Significant differences in nodulation of the legume species grown in the field also occurred between and within sites. Mucuna pruriens and Lablab purpureus produced more shoot and nodule biomass than the other legumes in all sites. Growth of most of these legumes responded to fertilizer application, except for C. verrucosa and Aeschynomene histrix. Except for C. verrucosa, average proportion of N2 fixed was about 80% and this was reduced by about 20% with N fertilizer application. The majority of rhizobia isolates (60%) were slow growing, belonging to the Bradyrhizobia spp. group. Selected rhizobia isolates evaluated on Cajanus cajan, C. pascuorum, M. pruriens and Psophocarpus palustris varied from ineffective to highly effective in Leonard jar conditions. However, only growth of M. pruriens responded to inoculation in potted soils, whereas it was lower than that obtained with N fertilizer application. This indicated the need to screen more rhizobia in order to improve N2 fixation and growth of legume species such as M. pruriens when it is introduced in soils deficient in N.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00335920
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  • 8
    Electronic Resource
    Electronic Resource
    Nodulation and estimation of symbiotic nitrogen fixation by herbaceous and shrub legumes in Guinea savanna in Nigeria (1996)
    Springer
    Biology and fertility of soils 23 (1996), S. 441-448 
    Details
    ISSN: 1432-0789
    Keywords: Key wordsBradyrhizobium spp. ; Effectiveness ; Guinea savanna ; Isolation ; N fertilizer ; Soil origin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Twelve herbaceous and shrub legume species were grown in pot and field experiments in five sites representing three agroecological zones in moist savanna in Nigeria. The objectives were to: (1) assess natural nodulation of the legumes and characterize their indigenous rhizobia, (2) determine their need for rhizobia inoculation and (3) estimate the amount of N2 fixed by each of these legumes. At 4 weeks after planting (WAP), Crotolaria verrucosa was not nodulated at any of the sites while Centrosema pascuorum had the highest number of nodules in all sites. At 8 WAP, all legumes were nodulated, with Mucuna pruriens having the least number of nodules and Stylosanthes hamata the highest. The number of nodules, however, was inversely correlated to the mass of nodules. Significant differences in nodulation of the legume species grown in the field also occurred between and within sites. Mucuna pruriens and Lablab purpureus produced more shoot and nodule biomass than the other legumes in all sites. Growth of most of these legumes responded to fertilizer application, except for C. verrucosa and Aeschynomene histrix. Except for C. verrucosa, average proportion of N2 fixed was about 80% and this was reduced by about 20% with N fertilizer application. The majority of rhizobia isolates (60%) were slow growing, belonging to the Bradyrhizobia spp. group. Selected rhizobia isolates evaluated on Cajanus cajan, C. pascuorum, M. pruriens and Psophocarpus palustris varied from ineffective to highly effective in Leonard jar conditions. However, only growth of M. pruriens responded to inoculation in potted soils, whereas it was lower than that obtained with N fertilizer application. This indicated the need to screen more rhizobia in order to improve N2 fixation and growth of legume species such as M. pruriens when it is introduced in soils deficient in N.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00335920
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  • 9
    Electronic Resource
    Electronic Resource
    Abundance of springtails (Collembola) under four agroforestry tree species with contrasting litter quality (1998)
    Springer
    Biology and fertility of soils 27 (1998), S. 15-20 
    Details
    ISSN: 1432-0789
    Keywords: Key words Collembola ; Agroforestry ; Prunings ; Grass ; Litter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The soil- and litter-dwelling Collembola under four agroforestry tree species (Treculia africana, Dactyladenia (Acioa) barteri, Gliricidia sepium and Leucaena leucocephala) were monitored monthly for a period of 12 months and results were compared with those of a secondary forest and a grass plot. Treculia and Dactyladenia produced lower quality litter, leading to lower soil temperature and higher soil moisture under those species, relative to Gliricidia and Leucaena. The agroforestry tree plots contained more soil- and litter-dwelling Collembola than the secondary forest and grass plots. The slowly decomposing litter under Treculia and Dactyladenia supported more litter Collembola than the quickly decomposing litter under Gliricidia and Leucaena. Soil moisture and temperature were, respectively, positively and negatively correlated with populations of soil Collembola. Based on the results of this study, it is suggested that the use of prunings of agroforestry tree species as mulch in agroecosystems would encourage the growth of Collembola populations and enhance their role in decomposition processes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740050393
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  • 10
    Electronic Resource
    Electronic Resource
    Effects of soil fertility and fertilizer application on biomass and chemical compositions of leguminous cover crops (1998)
    Springer
    Nutrient cycling in agroecosystems 51 (1998), S. 231-238 
    Details
    ISSN: 1573-0867
    Keywords: fertilizer ; herbaceous legumes ; lignin ; N ; polyphenols ; residue quality ; response ; root and shoot biomass ; soilfertility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The biomass and chemical compositions of selected leguminous cover crops Aeschynomene histrix, Cajanus cajan, Centrosema brasilianum, Centrosema pascuorum, Chamaercrista rotundifolia, Crotalaria verrucosa, Lablab purpureus, Psophocarpus palustris, Pseudovigna argentea, Mucuna pruriens, Pueraria phaseoloides, and Stylosanthes hamata were studied in a pot experiment, using soil with two fertility levels. Biomass yield responded to soil fertility levels and fertilizer application. The highest response to soil fertility was observed with C. brasilianum (340%, 200% and 310% more shoots, roots and nodules in high fertility soil than low fertility soil without fertilizer application). The highest response to fertilizer application was with P. palustris (500% more shoots with fertilizer than without in high fertility soil), with C. rotundifolia (410% more roots with fertilizer than without in low fertility soil), and with L. purpureus (1330% more nodules with fertilizer than without on high fertility soil). Legumes grown without fertilizer application allocated more biomass to roots than those with fertilizer application. Chamaercrista rotundifolia, L. purpureus, P. argentea, M. pruriens and C. cajan showed higher N content in roots than in shoots. Soil fertility levels did not affect N content of shoot, while fertilizer application increased it by 30%. Except for C. cajan (only shrub species), all the herbaceous legumes had lower lignin content (6–10%) in the shoots. The mean lignin content in roots was above 20% with no fertilizer, and decreased with fertilizer application compared to the no fertilizer treatment. The polyphenol concentration in shoots was higher than in roots.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009785905386
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