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Relationships between land use, fertility and the andisol characteristics : examples from insular volcanic settings

Perret S., Dorel M.. 1998. In : Cost 622 Action Meeting, Soil Resources of European Volcanic Systems. Montpellier : CIRAD, 9 p.. Cost 622 Action Meeting, Soil Resources of European Volcanic Systems, 1998-07-04/1998-07-10, (Islande).

Andisols have many intrinsic qualities that favour their use in cropping systems. They however prove to be very sensitive and their fertility decreases when they are badly managed. Concrete examples in insular volcanic zones make it possible to highlight the specific characteristics of these soils, and underline the permanent interaction between the potential of an environment, farming practices, and the reproducibility of cropping systems. The purpose of this paper is to show how land use seems to be a function of soil characteristics ... and vice versa ... The combined effects of slope and climatic aggression produce a situation in which erosion risk is very high, but variable according to cropping practices. The absence of anti-erosion provision, along with hoeing in the traditional cropping systems, and the tilling practices in the intensified market gardening systems, have disastrous consequences. Erosion causes deterioration of profiles, a decrease in plant vigour and proliferation of weeds. In industrial units (banana) it is the planting itineraries involving considerable motorisation that generate the deterioration of the profile, which has severe consequences on yields and production costs. In all these cases, a progressive decrease in production and cropping potential is observed. It shows up in falling yields, but also in the increase in inputs to bring out the potential of the medium (mechanical preparation and pest treatment in particular), and in an increase of risks (less scope and less security in the choice and implementation of cropping systems, and likewise in achieving yield). The examples developed on the paper underline the interplay of cropping systems and physical characteristics of andisols, and also the permanent interaction between the potential of the medium, practices, and reproducibility of the systems. (Résumé d'auteur)

Mots-clés : andosol; système de culture; fertilité; sol volcanique; utilisation des terres; Île; réunion; guadeloupe; france

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