Presents an overview of population and land use characteristics of the Kurmin Biri, Abet and Ganawwi areas, all in the subhumid zone of Nigeria, with particular reference to ethnic composition, human & cattle population, cultivation densities and extent of fallow land.

Data are given of area planted to beans, production, and yields in the Andean countries during 1964-66, 1974-76, and 1978; production, trade, and consumption during 1963-65 and 1973-75; and production, area, and yield growth rates during 1966-76. Constraints for bean productivity, cropping systems, and the main bean types consumed in the Andean countries are indicated. Finally, the potential of this crop is analyzed and data of land use and population patterns in the Andean countries are included. (CIAT)

As the problems of impact assessement are rather intractable, a fairly simple dual approach is proposed. First the major components of environmental impact of current agricultural production systems in Africa (i.e. impact of cropping, livestock keeping, fuelwood and timber extraction and burning) are summarised. Second, "danger zones" in which current and future environmental impacts will be most severe and on which ILCA has focused its problem solving-research is identified.

We examined whole-soil samples and particle-size fractions to study the distribution of different phosphorus (P) fractions after land-use change from native savanna to crops, pasture, and reforestation on clayey and loamy Oxisols of the Brazilian savannas. Phosphorus was extracted sequentially, according to a modified Hedley procedure, into inorganic and organic P (NaOH-extractable Pi and Po, respectively), and recalcitrant P (P HCl and P res). Under natural conditions of strong P deficiency, over 60% of NaOH-extractable P was organic, reflecting the high contribution of P.

This study assessed the influence of land use (continuous cropping, CC; tree plantations, F; pasture, PG; and native savanna, NS) on P concentrations and partitioning in bulk soil and two aggregate size fractions of two Oxisols, one loamy and one clayey. The quantity and quality of physically protected P within aggregates were also determined. Total P in bulk soil and macroaggregates (0.25-2 mm and 2-8 mm) was partitioned into inorganic and organic P fractions (P, and P., respectively) after sequential extraction, using NaHCO, (Olsen), NaOH, HCl, and H2SO4 (residual).

The 1st yr of operation (1983-84) of 6 cassava natural drying plants, established in some states of the Colombian Atlantic Coast as a result of the successful operation of the Betulia pilot plant (Sucre) established in 1981, is reported. Under the present production and commercialization conditions, the natural drying process of cassava proved to be an economically profitable activity in the region; however, it was sensitive to fresh root price and the degree of drying plant occupation. The major constraint to increased cassava yields is the lack of programs to produce healthy seed.