In Laos, the agrarian transition is characterized by rapid changes in agricultural production systems. Since the early 2000s, a transition has been taking place, away from subsistence agriculture, primarily based on rice cultivation, forest gathering and extensive livestock farming, and towards market-oriented agricultural production systems, with a significant and rapid increase in crops grown for export (Figure 5.1) to neighbouring countries, mainly China, Thailand and Vietnam. This transition has been facilitated by the implementation of successive public policies to limit the use of shifting cultivation and to modernize agriculture (Box 5.1), and by the result of the country becoming

La dégradation de l’environnement, l’évolution de la demande des produits alimentaires et non alimentaires, la globalisation des marchés et les fluctuations rapides des prix des produits agricoles conduisent à une modification rapide des systèmes de production et nécessitent des changements profonds des pratiques (Meynard et al., 2012). Les systèmes de culture doivent évoluer pour s’adapter à ces changements et faire face aux tensions qui en découlent : tensions entre rentabilité économique et préservation de l’environnement, entre intérêt individuel des exploitations et gouvernance territoriale, et entre filières (Meynard et al., 2012). L’agriculture de conservation (AC), en rupture avec les systèmes conventionnels, ouvre de nouvelles perspectives pour des systèmes de culture combinant durabilité et profitabilité. Elle se décline autour de trois principes fondamentaux : (i) un travail du sol minimal, si possible nul ; (ii) une couverture permanente du sol et (iii) des rotations/associations de cultures (Kassam et al., 2009). Mais les performances de l’AC sont variables et les systèmes doivent être adaptés localement, en fonction des conditions agro-climatiques et socio-économiques (Erenstein, 2003; Lestrelin et al., 2012). L’adaptation de ces systèmes à des milieux très divers demande de revoir leur mode de conception et l’accompagnement de leur diffusion. Ceci est particulièrement vrai pour les systèmes à base de riz pluvial, qui représentent 40 % des surfaces cultivées en riz en Afrique (Bernier et al., 2008) et sont à la fois mis en œuvre dans une très grande diversité de situations, très sensibles à la dégradation des sols et exposés à de fortes fluctuations des marchés.

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

The Plain of Jars is an acid, infertile savannah grassland covering an area of about 60,000 ha in the western region of Xieng Khouang Province, northeastern Lao PDR. In this ecology, farming systems are mainly based on lowland rice cultivation and extensive livestock production. An increase in rice production and intensification of the livestock industry are two key components in the Lao government's poverty alleviation strategy for this area.

This cattle breed used seems well adapted for fattening and showed a strong response to improved fodder. However, this bull fattening activity presented two major constraints.First, it seems difficult for smallholders to carry out this kind of livestock production without technical support and use of fertiliser (thermophosphate). The second limiting factor could be that the system was first perceived as requiring an initial cash investment.Development of specific market channels for forage seed production could indirectly improve pasture management, avoid high stocking rates and generate new income that could be invested in fertiliser and animal care. A global approach involving credit access, technical and political support has to be defined to develop productive and efficient livestock production on this ecology. This poses a great challenge which, if grasped, could yield great benefits on the upper part of the Nam Ngum river basin.

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.

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.

This rice-beef system "creation-validation" process shows the need to maintain research activities to feed the development process and the merits of the approach for determining the potential for technology dissemination.

DMC Systems for Rice--Beef Production in the Plain of Jars, Xieng Khouang Province, Lao PDR: Province, An Example of Creation--Validation Methodological Approach

Dans les zones de montagne au Nord du Vietnam, la faible fertilité chimique résultant d’une gestion traditionnelle oblige à une correction pour espérer des niveaux de production satisfaisants. Cependant, la faible capacité d’investissement des populations agricoles ne leur permet pas d’avoir recours à des apports massifs en engrais chimiques et amendements organiques et calcaires. L’écobuage, qui consiste en une combustion lente et partielle de la matière organique du sol, permet de retrouver des conditions favorables à moindre coût. Il doit être obligatoirement associé aux couvertures végétales.