In recent years, large-scale agricultural investment projects have increased in sub-Saharan Africa as a result of the growing appetites of local and international investors for land resources. Research has so far mainly focused on land issues, but the water implications of these land deals are starting to surface. Taking the Office du Niger (ON), in Mali, as a case study, it is shown that while around 100,000 ha is currently being cultivated, mostly by smallholders, a total of 600,000 ha of land has been allocated in the past ten years to investors in large-scale farming.

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.