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

Proposition of network of Conservation Agriculture in Southwest Asia

Changes in soil aggregation, soil water-holding capacity and soil biological activity under no-till systems and cropping sequences in the Lao PDR

A holistic approach, based on a permanent link between research and development, has been implemented by the Lao National Agro-Ecology Programme (PRONAE – PCADR,NAFRI), the Rural Development Project of the four southern districts of Xayabury province (PASS – PCADR, LCG), and the Sector-based Programme on Agroecology (PROSA, MAF), in partnership with the department of agriculture and forestry of Xayabury and Xieng Khouang provinces.

Methodology of DMC. A Holistic Approach to Generate, Adapt, Validate andDisseminate Technologies with Smallholders

Formation d'un réseau Agroécologie pour l'Asie du Sud-Est pour réunir les données, organiser des ateliers et visites des terrains et créer un site internet. Creation of a netwwork in agroecology in order to organize workshop, meetings, fields visits and website.

Traditional farming systems have drastically changed over the last fifteen years in southern Xayabury province through considerable agricultural development based on rainfed cash crops production such as maize, rice-bean (Vigna umbellata), peanut, Job's tears (Coîx lacryma), black cowpea (Vigna unguiculata) and sesame. This development depends mainly on local market accessibility, transfer of technologies from Thailand and financial capacities of local traders (inputs, heavy mechanization and technical skills from Thailand).

Farming systems throughout the Lao PDR have changed drastically over the last 15 years due to a range of factors. In some areas where market forces are prevalent, shifting cultivation systems have given way to more conventional high-input agricultural systems. In other more remote areas, the traditional swidden system with long rotations has been put under pressure primarily due to modification of land access and increasing population pressure. In southern Xayabury in the Mekong corridor, where there is access to the Thai market, land preparation has become based on burning residues and ploughing on steep slopes. Because of the environmental and financial costs of land preparation, farmers are shifting to herbicides, which lead to chemical pollution, while crop residues and weed mulch are usually burned, thereby increasing mineral losses and erosion on bare soil. In mountainous areas such as Xieng Khouang Province, the rationale of shifting cultivation is collapsing as farmers use land for longer periods of cropping and return more frequently to each field. A holistic research approach has been implemented in Xayabury and Xieng Khouang to find direct seeding mulch-based cropping (DMC) systems that are compatible with farmers' strategies and which can be reproduced inexpensively on a large scale. The methodological framework, based on five main components, emphasises the process of adaptation and validation by farmer groups, meaning that priorities are defined by smallholders in light of the constraints of their farming systems and the overall environmental conditions.

Implementing direct seeding techniques and rotations with cash crops for the upland rice system. Two main systems of direct-seeded rice were conducted are implemented : i) on former crop residues, ii) on former and cover crop(Brachiaria ruziziensis).

The present study, conducted during the rainy season 2002, analyses agro-economic components of conventional transplanting and direct seeded rice on lowland ecosystem (lower and upper terrace). Direct seeded rice varieties, on weeds and rice residues, have been tested on uppers terraces where no conventional rice system could be performed.