Analyse de la durabilité de la fertilité acquise suite a des jacheres arborées au Nord-Cameroun
Different of tree species were used as monospecific stands dduring the fallow period in the Garoua region (North Cameroon, Sudanian climate with 1200 mm rainfall). As far as the ability of the system to use the N pool of the soil and to stock nutrients either in the above ground biomass (where they are partly exploited during fallow period) or in the beneath ground biomass (where they can be returned to the crop following the fallow period after biological degradation) is concerned, results obtained independently of the present study have shown that the bio-geochemical cycles of the major nutrients in these conditions depends on the tree specie used. The response of a maize crop such fallow practices and the impact of these practices on the soil fertility status were assessed by comparison either with plots under permanent cultivation or under cropping systems including a grassland fallow. Comparison of analytical results obtained on the soil before and after the fallow period shows that after the stand being cut and the debris burned in the field, the exchangen properties of the soil are improved for all the tree species tested. An improvement of the soil organic status is noticed only where Acacia polyacantha was used. Other analyses done before the burning of the debris demonstrate the strong effect of this burning on soil exchange properties. Nutrients losses through lixiviation are moderate. The use of the N pool of the soil depends on climatic conditions and on the nature of the debris ploughed in or available in the soil. Periods of apparent immobilisation for mineral N are observed during the growing of the maize. Roots of Acacia polyacantha remain for a longer period in the soil after the trees have been cut and removed from the field than roots of the other species. The organic matter richness of the studied plots is closely reflected by soil fertility biological indicators. The above ground biomass of the maize crop, its rooting system development and the grain yield depend greatly on the tree specie used during the fallow period. As far as fertility conservation and grain production are concerned, the best specie is Acacia polyacantha.
| Main Authors: | , , |
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| Format: | biblioteca |
| Published: |
2000
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| Subjects: | ACACIA POLYACANTHA, ARBOLES FORESTALES, BARBECHO, BIOMASA, CASSIA SIAMEA, CICLO BIOGEOQUIMICO, EUCALYPTUS CAMALDULENSIS, MONOCULTIVO, NITROGENO, SISTEMAS DE CULTIVO, SUELO, |
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