Chapitre 23. Rôle des vers de terre et des termites pour la restauration de la productivité des sols en milieux tropicaux

Les invertébrés de la macrofaune du sol, comme les vers de terre et les termites, jouent un rôle clé dans le fonctionnement des sols. Ils décomposent la litière et l’incorporent au sol, ils construisent et maintiennent la structure du sol en creusant des galeries et en modifiant l’agrégation du sol, ils contrôlent en partie la diversité et les activités microbiennes, ils protègent les plantes contre les maladies et les pathogènes. En modifiant l’agrégation et la porosité du sol, en décomposant la matière organique, ces organismes participent à l’infiltration et au stockage de l’eau dans les sols, au recyclage des nutriments, à la régulation du ruissellement de l’eau, au stockage du carbone. Ces processus sont à la base des services écosystémiques. Pourtant, le rôle bénéfique de ces organismes dans la productivité des sols et la fourniture de services écosystémiques est encore mal connu et peu utilisé par les gestionnaires du sol (agriculteurs, etc.). Ils sont pourtant des indicateurs de la qualité des sols et doivent être considérés comme une ressource permettant de mieux gérer et améliorer la fourniture de services par les agroécosystèmes tropicaux.Invertebrates of soil macrofauna, such as earthworms and termites, are key organisms regarding soil functioning. They are involved in litter decomposition and incorporation in soil, they build and maintain soil structure through burrowing and modification of soil aggregation, they partly control microbial diversity and activities, and they protect plants against disease and pests. Doing this, they contribute to water infiltration and storage in soil, to nutrient recycling, to the regulation of water runoff, and to carbon sequestration. These ecosystem processes are at the roots of ecosystem services. Nevertheless, the beneficial roles of these ecosystem engineers in soil productivity and the supply of ecosystem services are still very poorly used by farmers and soil stakeholders. But they are relevant indicators of soil quality and should be considered as a resource potentially allowing a better soil management and promoting the provision of ecosystem services by tropical agroecosystems

Chapitre 6. Les aspects spatiaux et environnementaux de l’agriculture biologique

La protection de l’environnement (pris dans toutes ses composantes physiques, chimiques, biologiques, humaines) est l’un des objectifs majeurs mis en avant par les défenseurs de l’agriculture biologique (AB), au même titre que la qualité des aliments, la santé des exploitants ou encore la rentabilité économique de l’exploitation. En ce sens, l’AB est souvent qualifiée d’agriculture durable et apparaît comme un mode de production à promouvoir. L’agriculture biologique tente de créer, par ses p..

Gestion des ravageurs des cultures en ACS

Chapitre 9International audienc

Gestion des ravageurs des cultures en ACS

Chapitre 9International audienc

Chapitre 5. Systèmes de production agrobiologique : bases d’élaboration et perspectives de mise en place

Le propos de ce chapitre est d’exposer, dans le cas de la Martinique, de possibles combinaisons des paramètres techniques concernant la gestion des sols, des cultures et des animaux – présentés au chapitre 4 – au sein de systèmes de production cohérents, pour le cas de la Martinique. Issue du croisement de plusieurs courants scientifiques, la systémique est apparue dans le milieu du xxe siècle. En France, de Rosnay (1975) définit le système comme « un ensemble d’éléments en interaction dynami..

Pasture damage by an Amazonian earthworm

International audienc

Chapitre 2. Contexte de l’agriculture martiniquaise : atouts et contraintes pour l’agriculture biologique

L’activité agricole a été le moteur de l’économie martiniquaise durant plus de trois siècles. Au xviiie siècle, ce sont les cultures de café, de cacao, de tabac et d’indigotier qui ont soutenu les activités humaines et modelé progressivement le paysage. En réalité, ces productions n’ont pas réussi à s’imposer comme les garants d’un véritable développement économique, en raison de leur vulnérabilité face aux manifestations météorologiques paroxysmiques ; à quatre reprises, de 1713 à 1780, la M..

Development of the soil macrofauna community under silvopastoral and agrosilvicultural systems in Amazonia

In the Brazilian Amazon region, millions of hectares of forest land have been converted into cattle pastures and then been abandoned. Agroforestry is a potential option for the transformation of in parts degraded lands into productive agricultural systems. The re-establishment of a diversified soil macrofauna can help in the process of recuperation of the often compacted soil structure of the pastures. The soil macrofauna community was studied during the rainy season in four different agroforestry systems near Manaus in Central Amazonia: 1. a high-input silvopastoral system (ASPh), 2. a low-input silvopastoral system (ASPI), 3. a palm based system with four tree crop species (AS1) and 4. a high-diversity tree crop system with ten tree crop species (AS2), plus a spontaneous fallow for comparison. The sampling method recommended by the Tropical Soil Biology and Fertility Programme was used. The highest diversity of fauna groups was observed in the ASPh and ASPI where trees were associated with the leguminous cover crop, Desrnodiurn ovalifoliurn. The cover crop exerted a favorable effect on the soil fauna presumably by maintaining the soil moist and shaded and providing litter as a substrate. Of the 15 soil fauna groups that were found in all systems, four were absent from AS1. Within the AS2 system a significantly greater density of the soil fauna was observed under peach palm (Bactris gasipaes) and cupuaçu (Theobroma grandiflorum) (3107 and 524 ind.m-2, respectively) than under the other three tree species. The soil under peach palm and cupuaçu also tended to have a higher number of soil fauna groups. In AS1, the soil under peach palm had a higher fauna density than the soil under cupuaçu, probably caused by the abundant residues of the heart of palm harvest on the soil. The earthworm biomass was particularly high in AS1. Under cupuaçu approximately 7 times more earthworms were found in AS1 (17.9) than in AS2 (2.4). The study of the macrofauna community, including both the litter layer and the superficial soil layers, allows to identify the plant species/management combinations which favour the increase of the diversity of the invertebrates

Soil macrofaunal communities in permanent pastures derived from tropical forest or savanna

Soil macrofauna are sensitive to land use changes and this may have implications to soil functioning. The impact of the conversion of native ecosystems into extensive or intensive pastures on soil macrofauna were assessed with a standardised methodology in two neotropical phytogeographical regions, i.e. a tropical savanna area (Eastern Plains of Colombia) and a tropical rain forest area (Brazilian Amazon). In the savanna area, extensive cattle ranching only led to a slight enhancement of earthworm populations and to short-term fire-induced decreases of macrofaunal density. In intensive pastures, the initial taxonomic richness and composition of soil macrofauna were maintained, while native earthworm biomass was strongly increased. This may be explained by the similar mesologic conditions between these systems (similar vegetation structure) and by the higher quality of the organic inputs in the pastures (roots, litter and cattle faeces). Increased macrofaunal activity with a high taxonomic diversity is expected to have positive impacts on the sustainability of pastures in Colombian savannas. In the Amazon basin, slashing and burning of the forest for intensive pasture establishment resulted in more dramatic effects on native macrofauna. Taxonomic diversity was particularly strongly affected. Native earthworm species were largely depleted at the expanse of exotic peregrine species like, e.g. Pontoscolex corethrurus. These results are probably bound to the deep environmental changes that follow the conversion of forest into grassland ecosystems. Such modifications of macrofaunal communities are known to have potential negative effects on soil functioning and on the sustainability of agropastoral systems in this area. © 2004 Elsevier B.V. All rights reserved