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.

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).

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.

Since the 1990s, in the southern districts of Xayabury province in the Mekong corridor, traditional farming systems have changed through extensive agricultural development based on cash-crop production. This development, by way of intensification, depends on local market accessibility, transfer of technologies from Thailand and the financial capacities of local enterprises. Thai Inputs, heavy mechanisation and technical skills are imported and cropping is largely opportunistic, following Thai market demand. Land preparation, based on burning residues and ploughing on steep slopes, has allowed for cultivation of large upland areas. As a result of this development, combined with land allocation and increasing population density, fallow periods are disappearing. Furthermore, this resource-mining' generates land erosion, fertility loss, yield decline and chemical pollution as well as destruction of roads and paddy fields. In light of this, the Lao National Programme of Agroecology has implemented a holistic research approach in order to propose various systems for integrating crops and livestock production to farmers. From a large range of technologies that were tested, maize production using direct seeded grain on former crop residues under no-tillage systems has been implemented. Results achieved'under the various conditions are presented in this paper: the yields obtained are close to and sometimes even higher than those obtained in conventional systems. Labour, costs, soil erosion, net income and labour productivity are also all observed.