In Madagascar Highlands, population pressure and intensive rice cultivation in the lowlands has led to cultivation on the fragile, low fertility soils of the hillsides. Fertilisation being limited, yields remain low while erosion leads to paddy field silting-up and destruction of downstream infrastructures. To overcome these problems, experiments on direct planting on permanent soil cover (DPPSC) have been conducted since 1991 in the Andranomanelatra farm and since 1994 in farmers' fields, covering a wide range of biophysical and socio-economic situations

Les techniques de semis direct sur couverture végétale ont été développées au Brésil au cours de la dernière décennie. Ces techniques proposent un changement de paradigme et ouvrent de nouvelles perspectives pour l'agriculture. Elles sont maintenant utilisées sur des millions d’hectares, dans le monde entier. Depuis 1999, elles sont en cours d’adaptation aux conditions du Centre et du Nord du Vietnam, pour les zones de collines et de montagnes. Elles sont basées sur quelques principes fondamentaux.

Is it possible to coordinate the strategies and actions of multiple actors around the common goal of developing and diffusing Conservation Agriculture (CA) practices? How crucial is farmer participation in these efforts? How much of an emphasis should be placed on CA technologies vs. other types of innovations? The initial steps of the ASOSID project provide partial answers to these questions in the context of the Bajio, a semi-arid, subtropical region of Central Mexico dominated by post-green revolution, highly productive irrigated small-scale farming, presently facing decreasing profitability of cereal production, dwindling availability of irrigation water and soil fertility degradation.

CIRAD has developed in Central Java, in collaboration with the Center for Soil and Agroclimate Research and Development CSARD (Bogor), an innovative, multi-disciplinary and multi-scale participatory approach aiming at developing sustainable rainfed agriculture often synonymous with marginalized rural communities, food insecurity, povertyand inappropriate land and water management practices that have resulted in a continuous and insidious decline in productivity.

Ce poster relatant les propositions de GEC/Mediacom en matière d'Internet a été présenté à la conférence GFAR 2003 de Dakar.

The role of soil fauna, especially macro fauna, in soil genesis processes is now well known (Ketterings et al, 1997, Caesar-Thon That and Cochran, 2000). Thus, soil macro- fauna and its activity can accurately reflect soil functioning: recent works showed a direct and proportional relationship between earthworms activity and vegetal growth. These changes in micro and macro-fauna populations, abundance, and diversity and the soil biological activity all follow the same trends: a rapid decrease upon cultivation with traditional systems, and a fast improvement when a vegetal cover is permanently kept on the soil and plants with strong root systems improve its structure. These evolutions are similar to trends in yield evolution under various cropping practices. DPPSC systems proved to be highly efficient in restoring biological activity and fauna diversity in degraded soils.

Dry-farming system is commonly used in the Algerian semi-arid High Plateaus. It is based on cereal/sheep production in a cereal-fallow rotation. This cropping system degrades the structure f thetilled horizon and reduces its organic matter content (Kribaa et al, 2001). Soil structure degradation is reported as a major constraint regarding water infiltration, redistribution and storage in the soil profile (Canolly, 1998). It often results from the disturbance induced by tillage-tools. Under the crop growth conditions of the Sétif High Plateaus, as far as soil humidity is concerned, it appeared clearly that fallow till gave best results than no-till. This may be explained by the surface crusting that seals soil and by the absence of pores connectivity in the no-tilled fallow which penalized crop at the beginning of the season through a low stand. Hence under the no-till option,chiselling i.e. no soil reversing seems required. Direct seeding on cover crop may also be explored in theses conditions.

General results: reduction of labour very positive. Gain in weeding operations makes agriculture more adapted to women and children or even farmers weaken by HIV-AIDS. Good adoption of manual direct planters (11 “planting canes” and 6”sowing wheels”).

15 posters systèmes de culture, matière organique, semis direct

Face aux changements climatiques, économiques et sociaux, les agronomes examinent, à l'échelle du globe terrestre, de nouvelles voies pour l'agriculture. Leur but est de développer, pour et avec les agriculteurs, des solutions pour chaque situation, qui peuvent être adoptées rapidement, en particulier par les plus pauvres.