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  • Leucaena leucocephala  (4)
  • Denitrification  (2)
  • 1
    Electronic Resource
    Electronic Resource
    N dynamics and sources of N2O production following pig slurry application to a loamy soil (1998)
    Springer
    Biology and fertility of soils 26 (1998), S. 224-228 
    Details
    ISSN: 1432-0789
    Keywords: Key words CO2 production ; N2O production ; Nitrification ; Denitrification ; NH3 volatilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Carbon (C) and Nitrogen dynamics and sources of nitrous oxide (N2O) production were investigated in a loamy soil amended with pig slurry. Pig slurry (40000kgha–1) or distilled H2O was applied to intact soil cores of the upper 5cm of a loamy soil which were incubated under aerobic conditions for 28 days at 25°C. Treatments were with or without acetylene (C2H2), which is assumed to inhibit the reduction of N2O to dinitrogen (N2), and with or without dicyandiamide (DCD), which is thought to inhibit nitrification. Volatilization of ammonia (NH3), pH, carbon dioxide (CO2) and N2O production, and ammonium (NH4 +) and nitrate NO3 –) concentrations were monitored. The pH of the pig slurry amended soil increased from an initial value of 7.1 to pH 8.3 within 3 days; it then decreased slowly but was still at a value of 7.4 after 28 days. Twenty percent of the NH4 + applied volatilized within 28 days. Sixty percent of the C applied in the pig slurry evolved as CO2, if no priming effect was assumed, but only 38% evolved when the soil was amended with DCD. Pig slurry significantly increased denitrification and the ratio between its gaseous products, N2O and N2, was 0.21. No significant increases in NO3 – concentration occurred, and N2O produced through nitrification was 0.07mg N2O-N kg–1 day–1 or 33% of the total N2O produced. C2H2 was used as a C substrate by microorganisms and increased the production of N2O.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740050371
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  • 2
    Electronic Resource
    Electronic Resource
    Denitrification, N2-fixation and fermentation during anaerobic incubation of soils amended with glucose and nitrate (1996)
    Springer
    Biology and fertility of soils 23 (1996), S. 229-235 
    Details
    ISSN: 1432-0789
    Keywords: Denitrification ; N2-fixation ; Fermentation ; N2O/N2 ratio ; C-availability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Nitrate and glucose additions were investigated for their role in the C and N dynamics during anaerobic incubation of soil. A gas-flow soil core method was used, in which the net production of N2, N2O, NO, CO2, and CH4 under a He atmosphere could be monitored both accurately and frequently. In all experiments clayey silt loam soil samples were incubated for 9 days at 25 °C. Addition of nitrate (50 mg KNO3-N kg-1 soil) had no effect on total denitrification and CO2 production rates, while the N2O/N2 ratio was affected considerably. The cumulative N2O production exceeded the cumulative N2 production for 6 days in the treatment with nitrate addition, compared to 1.2 days in the unamended treatment. Glucose addition stimulated the microbial activity considerably. The denitrification rates were limited by the growth rate of the denitrifying population. During denitrification no significant differences were observed between the treatments with 700 mg glucose-C kg-1 and 4200 mg glucose-C kg-1, both in combination with 50 mg KNO3-N kg-1. The N2 production rates were remarkably low, until NO inf3 sup- exhaustion caused rapid reduction of N2O to N2 at day 2. During the denitrification period 15–18 mg N kg-1 was immobilised in the growing biomass. After NO inf3 sup- shortage, a second microbial population, capable of N2-fixation, became increasingly important. This change was clearly reflected in the CO2 production rates. Net volatile fatty acid (VFA) production was monitored during the net N2-fixation period with acetate as the dominant product. N2-fixation faded out, probably due to N2 shortage, followed by increased VFA production. In the high C treatment butyrate became the most important VFA, while in the low C treatment acetate and butyrate were produced at equal rates. During denitrification no VFA accumulation occurred; this does not prove, however, that denitrification and fermentation appeared sequentially. The experiments illustrate clearly the interactions of C-availability, microbial population and nitrate availability as influencing factors on denitrification and fermentation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00335949
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  • 3
    Electronic Resource
    Electronic Resource
    Alley cropping in the moist savanna of West-Africa: I. Restoration and maintenance of soil fertility on ’terre de barre‘ soils in Bénin Republic (1998)
    Springer
    Agroforestry systems 42 (1998), S. 213-227 
    Details
    ISSN: 1572-9680
    Keywords: Gliricidia sepium ; Leucaena leucocephala ; maize grain yield ; N accumulation ; Senna siamea ; wood biomass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The potential of alley cropping systems supplied with a limited amount of fertilizer to restore crop productivity on a degraded site and to maintain crop productivity on a recently cleared, non-degraded site on ‘terre de barre‘ soils in Southern Bénin was investigated from 1994 to 1996. Leucaena leucocephala, Senna siamea and Gliricidia sepium were used as hedgerow species. Maize yields of the no-tree control plots dropped from the initial (1990) 401 kg ha−1 and 2181 kg ha−1 on the degraded and non-degraded sites, respectively, to 109 kg ha−1 and 1346 kg ha−1 in 1996, even with application of a minimal amount of mineral fertilizer. The alley cropping systems produced on average (mean of three treatments and three years) 107% more grain than the initial 1990 values on the degraded site and 11% less grain than the initial 1990 values on the non-degraded site. Especially the Senna and to a lesser degree the Leucaena treatment yielded consistently more grain than the control. The Senna trees contained a larger amount of N and produced more wood during the first pruning on the degraded site (155 kg N ha−1 and 14.0 ton fresh wood ha−1) than on the non-degraded site (49 kg N ha−1 and 6.6 ton fresh wood ha−1) most likely because of differences in subsoil fertility, as indicated by the higher clay, exchangeable bases, and N content between 60 and 125 cm cm. N accumulation and wood production by the Leucaena and Gliricidia trees was similar in both sites (82 and 36 kg N ha−1 and 4.6 and 9.3 ton fresh wood ha−1, respectively). When a limited amount of fertilizer is available, Senna appears to be the best choice as hedgerow species on sites with a relatively fertile subsoil. For other soils, a N2-fixing species may be a better choice.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006114116095
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  • 4
    Electronic Resource
    Electronic Resource
    Alley cropping in the moist savanna of West-Africa: III. Soil organic matter fractionation and soil productivity (1998)
    Springer
    Agroforestry systems 42 (1998), S. 245-264 
    Details
    ISSN: 1572-9680
    Keywords: Albizia lebbeck ; Gliricidia sepium ; Leucaena leucocephala ; particle size classes ; particulate organic matter ; Senna siamea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In cropping systems with limited amounts of external inputs, the soil organic matter pool (SOM) may contribute significantly to plant nutrition. The impact of organic inputs on total SOM and particulate organic matter (POM) N contents as affected by soil type and the relationships between sources of N and maize N uptake were assessed for a set of alley cropping trials in the West- African moist savanna. The trials were established in Niaouli (Bénin Republic), in Glidji, Amoutchou, and Sarakawa (Togo), and in Bouaké and Ferkessédougou (Côte d‘ Ivoire). The total soil N content, averaged over all treatments and years, varied between 324 and 1140 mg N kg−1 soil. The POM-N content varied between 50 and 160 mg N kg−1 soil. The average proportion of soil N belonging to the POM pool ranged between 9% and 29%. This was significantly related to the annual N inputs from maize stover and prunings, when averaged over the different alley cropping treatments. The trial ‘age‘ also appeared to be related to the impact of the different treatments on the POM-N content. The Ferkessédougou soil contained a relatively higher proportion of total soil N in the POM pool because of its relatively high silt and clay content, compared to the other sites. The relative change in POM-N content between 1996 and the initial sampling was about twice the relative change in total soil N content. This suggests that N incorporated in the POM is relatively labile, compared to N incorporated in the other SOM fractions. Maize N uptake was related to the amount of add pruning-N (partial r2 of 27%), the rainfall during the growing season (partial r2 of 17%), the POM-N content (partial r2 of 14%), and to a lesser degree to the POM N concentration (partial r2 of 5%), the fertilizer N addition rate (partial r2 of 3%), and the silt and clay content of the soil (partial r2 of 3%). The POM-N content was shown to be influenced by organic matter additions and soil characteristics and to contribute significantly to maize N supply. This pool may be an important indicator for the soil fertility status of savanna soils.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006128401073
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  • 5
    Electronic Resource
    Electronic Resource
    Impact of residue quality on the C and N mineralization of leaf and root residues of three agroforestry species (1996)
    Springer
    Plant and soil 183 (1996), S. 221-231 
    Details
    ISSN: 1573-5036
    Keywords: Dactyladenia barteri ; Flemingia macrophylla ; Leucaena leucocephala ; lignin ; N-immobilization ; 15N labeled residues ; polyphenols
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A laboratory incubation experiment with 15N labeled root and leaf residues of 3 agroforestry species (Leucaena leucocephala, Dactyladenia barteri and Flemingia macrophylla) was conducted under controlled conditions (25 C) for 56 days to quantify residue C and N mineralization and its relationship with residue quality. No uniform relation was found between the chemical composition of the above and below residues. The leucaena and dactyladenia roots contained more lignin (8 and 26% respectively) and less N (2.0 and 1.0% respectively) than the respective leaves (2 and 13% lignin and 2.9 and 1.4% N, respectively), whereas the differences between the lignin and N contents of the flemingia leaves and roots were not significant (4.6 and 3.0% lignin and 2.63 and 2.68% N, respectively). The leucaena leaves contained more polyphenols than the roots (6.4 and 3.6%), while the polyphenol content of the leaves and roots of the other residues was similar (5.0 and 5.1% for dactyladenia and 4.0 and 3.5% for flemingia). Three patterns of N mineralization could be distinguished. A first pattern, followed by residues producing the highest amounts of CO2, showed an initial immobilization of soil derived N, followed by a net release of both soil and residue derived N after 7 days of incubation. A second pattern, followed by the flemingia leaf residues which produced intermediate amounts of CO2 and had an intermediate quality, showed no significant immobilization of soil derived N, and significant mineralization of residue N. A third pattern, followed by both low quality dactyladenia residues, showed a low release of residue derived N and a continued inmobilization of soil derived N. Residue C mineralization was significantly (p〈0.05) correlated with the residue lignin content, C-to-N ratio, and polyphenol-to-N ratio. The proportion of residue N mineralized (immobilized) after 56 days of incubation was significantly correlated with the residue N content (p〈0.01) and the C-to-N ratio (p〈0.05). The relations were quadratic, rather than linear. The ratio of the proportion of residue N mineralized (immobilized) over the proportion of residue C mineralized after 56 days was highly significantly correlated with the lignin content (p〈0.01) and C-to-N (p〈0.001), lignin-to-N (p〈0.01), polyphenol-to-N (p〈0.01) and (lignin+polyphenol)-to-N ratios (p〈0.01) in a linear way. This indicates that due to the low availability of the residue C, relatively less N is immobilized for the very low quality residues ((lignin+polyphenol)-to-N ratio: 29.7) than for the residues with a relatively higher quality ((lignin+polyphenol)-to-N ratios between 3.3 and 12.5).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00011437
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  • 6
    Electronic Resource
    Electronic Resource
    Alley cropping in the moist savanna of West-Africa: II. Impact on soil productivity in a North-to-South transect in Togo (1998)
    Springer
    Agroforestry systems 42 (1998), S. 229-244 
    Details
    ISSN: 1572-9680
    Keywords: Albizia lebbeck ; Gliricidia sepium ; Leucaena leucocephala ; maize grain yield ; N accumulation ; Senna siamea ; wood biomass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The moist savanna of West-Africa is characterized by a wide range of climates and soil types. The impact of the biophysical environment on hedgerow N uptake, wood production and maize grain yield was assessed for three years in three alley cropping trials with a selected number of hedgerow species in Glidji (Southern Togo), Amoutchou (Central Togo), and Sarakawa (Northern Togo). Senna siamea hedgerows accumulated significantly more N in the first pruning in Glidji (129−138 kg N ha−1) and Sarakawa (102−185 kg N ha−1) than in Amoutchou (17–26 kg N ha−1). This difference in N uptake was attributed to the infertile subsoil in Amoutchou, which was sandy up to 1 m and had a shallow groundwater-table. The amount of N accumulated in the Gliricidia sepium biomass varied between 38 kg N ha−1 in Glidji and 142 kg N ha−1 in Amoutchou. Averaged over all species and sites, 9 to 29% and 9 to 39% of the annual N accumulation in the hedgerow biomass is incorporated in the second, respectively third pruning. The Gliricidia trees produced between 12 and 26 ton fresh matter ha−1 of wood and the Senna trees between 4 and 38 ton fresh matter ha−1. Maize grain yield in Glidji was not affected by treatments (3196 kg ha−1, on average). In Amoutchou, the highest grain production was observed in the Gliricidia treatment (2774 kg ha−1 vs 1007 kg ha−1 in the control), while in Sarakawa, the Gliricidia (3786 kg ha−1) and Senna (3842 kg ha−1) plots produced a greater grain yield than the control plots (2123 kg ha−1). Maize yield increase in the alley cropping systems relative to the control plots was related to the soil total N content. Top and sub-soil characteristics were shown to be an important modifier of the functioning of alley cropping systems and should be taken into account when deciding on whether to use alley cropping and when selecting the hedgerow species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006124317003
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