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.

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

El Sistema de Información de Suelos de Latinoamérica (SISLAC), es una iniciativa regional impulsada y financiada por la Alianza Mundial por el Suelo (FAO) e implementada en alianza estratégica con CIAT, EMBRAPA y 20 instituciones nacionales de Argentina, Bolivia, Brasil, Chile, Colombia, Costa Rica, Cuba, Ecuador, El Salvador, Guatemala, Honduras, México, Nicaragua, Panamá, Paraguay, Perú, República Dominicana, Surinam, Uruguay y Venezuela.

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.