The International Rice Research Institute (Lao-IRRI Project) and the Lao National Rice Research Program have been collaborating on rice research since 1991. Soil fertility research has been conducted in all provinces of Laos through this effort. The objective of this book is to review the research that has been conducted on nutrient management of lowland rice in Laos from 1991 to 2000 and to present an integrated and sustainable nutrient management approach that is relevant to Lao farmers. We focus on the rainfed lowland rice system as opposed to the irrigated rice system, although references will be made to both. In the first section, an overview of lowland rice trends and practices in Laos will be given This will be followed by a discussion of the production environment, with emphasis on climate and soils. This will be followed by a presentation of research aimed at identifying nutrient deficiencies and nutrient management strategies to overcome these deficiencies. Finally, the last section provides an overall summary and recommendation for different soils. In the appendixes at the end, we have provided (1) a list of Lao-IRRI publications relating to rainfed lowland rice, which are available from IRRI, and (2) a list of soil fertility experiments that have been conducted from 1991 to 2000. It is from these experiments that the results of this book have been derived.