Phosphate Rock Evaluation: Sub-Saharan Africa Experience

摘要

There is overwhelming evidence that nutrient limitation is the main constraint to crop production in sub-Saharan Africa (SSA) including many areas in the Sahel. Both N and P needs have to come from external fertilizers, though legumes and green manurecrops as crop residues can contribute some of the N. Water-soluble P and/or phosphate rock (PR) will still be needed to grow the green manure crops and/or food crops. Effectiveness of PR with respect to water-soluble commercial P fertilizers may be confounded by soil properties, other limiting factors including nutrients, poor response to P application, low absolute yield increases, residual effects, and cropping systems, particularly the presence of legumes. Hence, it is not surprising that conclusions from PR studies in SSA have been conflicting. We have evaluated PR response in some of the more recent field trials trying to get a better understanding, and consequently work towards developing better predictive and recommendation tools for future applications.