Divers résumés en français et anglais des 4 symposiums relatifs à Brésil, Asie, Madagascar : 1 sur Séquestration C, 2 biologie du sol, 3 éléments nutritifs (N, P, fertilité), 4 érosion et conservation sol

Effet d'une légumineuse de couverture sur le ruissellement et l'érosion dans des systèmes de culture à base maïs au Sud Bénin: la culture - relais de maïs et mucuna augmente les rendements en maïs, enrichit le sol en matière organique, améliore l'agrégation du sol superficiel, diminue le ruissellement et l'érosion.

Diaporama sur définition Sol, MOS, érosion et SCV comme solution

The soil organic carbon (SOC) content depends strongly on soil management and especially the level and quality of organic restitution to the soil. The SOC pool is the net result of carbon (C) input in the form of crop residue and biomass, and output including CO2 flux and other losses (Duiker, 2000). Changes in soil management can alter SOC content. A substantial increase in the SOC content in the 10 cm topsoil layer in no-tillagesoils compared with soils under natural vegetation and long-term conventional tillage (CT) (Séguy et al. 2003 ) can occur due to high crop-residue input and lack of soil disturbance.

In the "Cerrados" of Central Brazil, direct seeding mulch based cropping systems (DMC) applied by farmers have been adapted to tropical conditions (high temperature,high rainfall and resulting high rates of organic matter mineralization). Generally, time saved with no-tillage allowed farmers to plant another crop in the same year, producing additional biomass, increasing thereby organic matter entries into the soil,and maintaining the soil surface always covered and protected from soil erosion (pictures). However, the level of biomass restitution, and the long term impact on C sequestration in DMC systems will differ in function of the type of commercial crop rotation, the species used as cover-crops, the level of productivity and the farmer's management (Séguy et al., 2003.