Based on the understanding of soil/plants/microorganisms interactions and the importance of the primary biomass production in the functioning of the soil system, OMC introduces multifunctional cover crops, growing intercropped or in sequence with the main commercial crop. The introduction of cover crops leads to better utilization of available natural resources, maximization of biomass production and higher organic restitutions to the soil system.

This paper provides a theoretical framework to identify the main features of each agricultural context. Based on four case studies within different soil conservation projects funded by the French Development Agency including Cameroon, Madagascar, Mato grosso in Brazil and France. The paper finally defines a practical framework to organize soil conservation interventions, developing theoretical basics for priorities in CA designing or complementary efforts programming.

Macro aggregates disruption, enhanced soil aeration and mixing of residues into the soil induced changes in microbial communities’ activity and organic C losses.

Version portugaise des chapitres 1 et 2 du Manuel pratique du semis direct à Madagascar, présentant les principes, le fonctionnement et la gestion des systèmes en SCV.

Version espagnole des chapitres 1 et 2 du Manuel pratique du semis direct à Madagascar, présentant les principes, le fonctionnement et la gestion des systèmes en SCV.

L’UR SCV développe avec ses partenaires des outils pour le diagnostic et le pilotage des Systèmes de culture en association permanente avec des agriculteurs. En Agriculture de Conservation (AC) la gestion des matières organiques du sol (MOS) est primordiale car elle détermine un potentiel de nutrition par voie biologique. Elle est aussi complexe en raison de la diversité des apports organiques concentrés à la surface du sol qui varient en quantité, en qualité et en proximité (Sa et al., 2001). Le modèle Hénin-Dupuis (Hénin et Dupuis, 1945, Mary et Guérif, 1994, Bayer et al., 2006) est utilisé comme outil de simulation à l’échelle de l’exploitation agricole des évolutions des stocks en MOS (ou C organique) à la surface du sol. Quatre étapes possibles et applicables au contexte tunisien sont présentées.

L’Agriculture de Conservation (AC) en Tunisie soumise à un climat semi-aride doit pouvoir, optimiser l’efficience des ressources en eau (400 mm/an) pour sécuriser la production de céréales et de fourrages. À court terme les techniques d’AC en améliorant les propriétés physiques du sol en surface par rapport aux système s traditionnels (Nouiri et al., 2008), permettent une meilleure infiltration de l’eau avec des quantités de résidus limitées.

The National Agroecology Programme (PRONAE) and the Southern Xayabury Application Point (PASS) of the Capitalization and Rural Development Support Programme (PCADR) have developed an approach in the provinces of Xayabury and Xieng Khouang that relies on direct sowing mulch-based cropping systems (DMC). This approach has provided relevant alternatives to traditional agricultural practices which can no longer ensure the foundations of sustainable agriculture.

The results of the WSA analysis are promising, highlighting the positive features of forage species like B. ruziziensis and S. guianensis, which seem able to aggregate smaller soil particles. Annual records should be made for B. ruziziensis, S. guianensis and others systems, and linked with analysis of microbial activities to show the beneficial functions of each species or system in soil aggregation. It is difficult to interpret the positive features of species in regard to bulk density and soil permeability as interaction is complex and various parameters are involved. At the same value of bulk density, this parameter will be affected by article size and arrangement, and organic content. In the case of rice and pine forest, the lower bulk density is mainly related to macro-porosity (high level of permeability). In contrast, B. ruziziensis and S. guianensis showed, for lower Da, a lower value of permeability probably related to an increase of micro-porosity. This characteristic has to be analysed during subsequent measurements of Da and soil permeability data as micro-porosity is a main component influencing water retention.

The National Agroecology Programme (PRONAE) and the Southern Xayabury Application Point(PASS) of the Capitalization and Rural Development Support Programme (PCADR) have developed an approach in the provinces of Xayabury and Xieng Khouang that relies on direct-sowing mulch-based cropping systems (DMC). This approach has provided relevant alternatives to traditional agricultural practices which can no longer ensure the foundations of sustainable agriculture.In view of the results obtained, be they socio-economic or environmental, the Council of Ministers asked the Ministry of Agriculture and Forestry (MAF) to promote these techniques throughout the country, and called for this approach to be included in university and school courses. It is in that context that the Sector-based Agroecology Programme (PROSA), whose main aim is to define and implement a national strategy for the dissemination of Conservation Agriculture based on agroecological techniques (DMC), operates.This strategy is based on implementing an Agroecology Action Plan relying on the necessary incorporation ofnatural capital in rural development policies. The plan involves programming activities, setting in place decision-making and operational processes and bringing into play financial, material and human resourceson both a central and local level (province, district and sub-district). The finest level of intervention comprisesgroups of farmers linked to service centres set up by the government within the districts (Kum Ban Pattana). On each level, the agroecology action plan is to arise from an integrated and concerted approach, in which each category of rural development stakeholders is committed to a process in which their needs and skills are acknowledged by all. Likewise, on each level, it is necessary to define, in a concerted manner, the initiatives that have to be taken (diagnosis, planning, implementation, monitoring-appraisal), the tools required (training of the different stakeholders, organization and structuring of the State sector and of the private sector, contractualization between stakeholders) and the fields of involvement (extension, local development funding arrangements, management of natural resources, equipment management, organization of supplyand marketing chains, etc.). Each of the two pilot provinces, Xayabury and Xieng Khouang, is in the process of defining its Provincial Action Plan in Agroecology. An initial diagnosis of farming systems and their environmental impacts, along with the needs and contributions of each category of stakeholders, has been completed. The provinces then gave priority to defining decision-making and operational processes, and setting in place financial arrangements for the Provincial Action Plans. Initially, two funding tools are under consideration: constitution of a development fund, and agricultural credit. On a central level, the decision-making and operational processes are directly attached to the Ministry of Agriculture and Forestry, notably via the Planning Department. The creation of a Research and ServiceProvider Centre in support of local and national development is envisaged. Likewise, on a central level, it is a matter of facilitating the implementation of training plans for the different stakeholders. Lastly, the inclusionof agroecology in university and school courses is under way. Also for the educational sector, it is necessary to define a training plan to strengthen the skills and abilities of teachers. The creation of a national, or even regional network associating agricultural faculties and agricultural schools would enable an economy of scale by more effectively taking advantage of complementarities and decentralization to a more functional local level.