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2014 05 bamako meeting jan de leeuw


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2014 05 bamako meeting jan de leeuw

  1. 1. Knowledge gaps trees, deep soil resources and rainfed crop production in dryland production systems Jan de Leeuw ICRAF Nairobi
  2. 2. Revival of interest groundwater in Africa • 2012 UCL Research 'Huge' water resource exists under Africa • NERC-UPGRO: Unlocking Potential of Groundwater in Sub Saharan Africa • Renewed interest in development of irrigated agriculture • Argument this should not compromise benefits from agroforestry systems
  3. 3. Perspectives on Agriculture in Sahelo Soudanian Zone • Crops – sorghum millet farming system • Livestock – pastoral / agro-pastoral systems • Trees – dryland agroforestry system • Mixed systems: annual crops, livestock and trees • Agricultural institutions (incl. research) focus on crops and livestock • Do trees merit more attention?
  4. 4. Commodity based perspectives • Agendas agriculture achieving DG’s • Leading to focus agricultural institutions on crop and livestock commodities • Negative side – Monocultures – diet and health – Barren unhealthy landscapes – Unsustainable natural resource management
  5. 5. Trees and multifunctional systems • Agricultural systems can be managed to include trees to optimize provisioning of multiple functions: – Water and nutrients – Dietary diversity – Healthy human habitat – Food security / resilience – Sustainability • Trees build many of these traits into agricultural production systems, some are direct many are indirect benefits • Ecosystem service perspective on benefits from trees – Provisioning services, food and other goods – Supporting and regulating services
  6. 6. The ecosystem goods: tree products • Positives – – Production of tree products more resilient to drought than crops or livestock – Food fruits, nuts, edible oils also available dry season – Construction- and fuel-wood, gum arabica, assets than can be used in case of shortage • Negatives – – Prone to over-utilization and degradation – Trees in the landscape are a fragile natural capital
  7. 7. Regulating service: Trees and groundwater • Hydraulic lift and redistribution groundwater • Driven by gradient in water potential • Moisturizing dry upper soil horizons • Benefiting shallow rooted species like crops
  8. 8. Supporting service: trees and soil fertility • Nitrogen fixation associated to roots and moisture • Redistribution nutrients from lower soil horizons
  9. 9. Example Faidherbia alibida • Groundwater dependent in drylands • Widespread in Africa • 5 million ha in Niger • 0.5 million ton increased cereal production • 1 million people benefiting • Are these benefits attributable to groundwater? • What is the potential for upscaling and how does that relate to groundwater?
  10. 10. Knowledge gaps nutrient enrichment and hydraulic redistribution • Biophysical principles well understood • Significance and benefits of poorly not quantified • Potential for designing more resilient agricultural systems to be explored
  11. 11. Trees and crops • Positive impact on crop production – Water balance – shade, hydraulic redistribution – Nutrients – Upward redistribution, N fixation • Negative impacts on crop production – Competition for water and nutrients • Gap - optimal design of tree - crop systems
  12. 12. Trees and livestock • Positive impacts – – Food - foliage and seeds as forage for livestock – Veterenary medicine – trees important • Negative impacts – – Livestock degradation tree cover and the sustainability of benefits derived from trees • Gap – designing sustainable integration of tree based forages and crop residues in livestock production systems
  13. 13. Need for a strategic perspective on groundwater and evergreen agriculture • Reawakened interest developing groundwater and irrigation • Danger of development of irrigated agriculture ignoring benefits from AF systems • Blue water paradigm dominates groundwater management • Paradigm shift required towards blue and green water management • Evidence required that trees in Sahelian landscapes generate significant social benefits
  14. 14. Take home messages • Trees enhance the production of the system as a whole, benefits of this poorly recognized • Trees system builders, multifunctional landscapes with many desirable traits including support to crop and livestock production • Research lacking on optimization and design of multifunctional landscapes and the role of trees in there