Synchronizing N release from organic residues: opportunities for integrated management of N.

In intensive cropping systems, mineral nitrogen (N) fertilizers represent the largest component of the N cycle because the indigenous N supply is not adequate. The requirement for mineral fertilizer may be reduced with the use of organic nutrient sources. A more realistic use of organic matter, particularly in sub-Saharan Africa due to limited amounts and availability, is the combined use of organic nutrient sources and mineral fertilizers.

Germination and establishment of Sahelian rangeland species : II. Effects of water availability.

In order to understand the vegetation dynamics of Sahelian rangelands, the effects of water availability on germination were investigated under controlled conditions in climate rooms. Mixtures of seeds from species that occur in the same habitats but have different seed characteristics were exposed to different watering treatments. Responses to the treatments in the climate room were comparable to those observed in the field situation.

Germination and establishment of Sahelian rangeland species : I. Seed properties.

In the context of a study on the dynamics of Sahelian rangelands, seed characteristics of about 30 species have been described, with particular attention to germination characteristics. Data on both form and weight of the seeds are presented. Germination was studied under controlled conditions in a climate room.

Rangeland productivity and exploitation in the sahel.

Results of a Malian-Dutch research project on the Sahelian pastures and their utilization suggest reasons why some efforts to develop traditional livestock farming in this area have been unsuccessful. Failure to appreciate the effects of low soil fertility as well as low rainfall on pasture production has resulted in underestimation of the productivity of the nomadic and seminomadic livestock farming system and overestimation of the possibilities for increasing production by better management and by modernization.