Swidden farming is the main agent of conversion of primary forests to secondary forests in the highlands of mainland Southeast Asia, but there is a deterioration and decline of the practice with land use intensification. The population growth in northern Thailand has forced lowland farmers practising permanent wet rice cultivation to turn to short rotation swidden in the foot hill zone. Highland swidden agriculturists are adopting more intensive forms of swidden or are shifting to permanent farming.

Maintaining indigenous nutrient supply and positive nutrient balances are key factors in sustaining rice yields. Irrigation systems act as conveyers for water, sediments and nutrients throughout landscapes, especially in mountainous, cultivated tropical areas where erosivity is usually high. Contributions of erosion and irrigation to the nutrient balance of paddy fields, however, are rarely assessed.

Chemical sequential extraction is widely used to divide soil phosphorus (P) into different inorganic (Pi) and organic (Po) fractions, but the assignment of these fractions to pools of differing plant availability, especially for low P tropical soils, is still matter of discussion. To improve this assignment, the effect of land-use systems and related P fertilizer inputs on size of P fractions and their isotopic exchangeability was investigated.

Presents results of studies of settlement, land use & relations w. settled farmers of Fulani agropastoralists in Abet & Kachia Grazing Reserve in Subhumid Nigeria. Discusses reasons of choice of site, pattern & right of grazing and access to land.

Objectives of this study were to compare costs and expected benefits of feed supplementation in cattle with alternative shrub legumes during the dry season using as a case study the hillsides of Central Nicaragua. The information used was gathered in a survey of 32 farms in the states of Boaco and Chontales in Central Nicaragua.

Synthesis reports on CIAT's investigations in the area of agrobiodiversity.