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Urbanization Global Soil Week

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					Soils and urbanization:
introduction
to sub-Saharan Africa issues
Jean Louis Morel
Chairman of SUITMA
Soils in Urban, Industrial, Traffic, Mining and
Military Areas – WG of the IUSS


            http://www.suitma7.umk.pl/
                                                                     1
                              1st   Global Soil Week – Urbanization – Berlin - 18-22 November, 2012
  Africa: contrasted situation with Europe




Energy
Land use
Urbanization



                          1st Global Soil Week – Urbanization – Berlin - 18-22 November, 2012
Situation in SSA is changing very fast*
• 2010 : more than 400 million in urban areas
• 2020 : 24 of the world’s 30 fastest growing cities will
  be African.
• 2030 : the urban population of sub-Saharan Africa is
  projected to reach 600 million
                 Population growth and poverty

• More than half of all residents live in overcrowded
  slums.
• Up to 200 million survive on less than US$2 a day



     *First status report on urban and peri-urban horticulture in Africa, FAO, 2012
                                        1st Global Soil Week – Urbanization – Berlin - 18-22 November, 2012
Major urban soil issue : food for all
• Keep soils unsealed to ensure food and nutrition
 security, and decent work and income
  • Urban and Peri-Urban Agriculture (UPA)
     • Local food system (home gardening, market gardening)




  Microgardening where “substitute” soils are designed to fulfill specific functions


• Towards healthy, “greener” cities,
 with improved environment
                                              1st Global Soil Week – Urbanization – Berlin - 18-22 November, 2012
Access to arable land: obstacles
                        • UPA on non-owned land
                        • Use of land safe from
                          construction
                            • to avoid rapidly changing areas
                            • road and railway sides, dumps,
                              industrial sites, etc.
                            • close to water sources
                              (e.g.sewage)
                            • overamended (rapid profit)




                        1st Global Soil Week – Urbanization – Berlin - 18-22 November, 2012
Niger: evolution of land use – case of Niamey
 • Niger : 1 267 000 km2
   • 12% arable land ; Niamey (capital) : 1 M inhabitants
                                             A                                                           B                Zone urbanisée non


 • Land use (2001)                         8 808; 37%
                                                                  Zone agricole (ha et %)

                                                                  Zone urbanisée (ha et %)
                                                                                                                          résidentielle(ha et %)
                                                                                                                          Zone résidentielle (ha et %)

                                                                                                             3 323; 38%

   • urbanized areas : 8808 ha (37%)                     15108; 63%                          5485; 62%


   • rural areas : 15 108 ha (63%)

 • Last 10 y: regression of agricultural surface
   • strong increase in population + difficult economic situation
   • uncontrolled urbanisation on very fertile land
   • city council selling agricultural plots
    for cash money
 • Soil contamination
   • Survey for hydrocarbons,
    metals (Cd, Pb, Zn)
    showing contamination

                                       A. Tankari Dan-Badjo - Faculté d’Agronomie de Niamey;
                                             1st Global Soil Week – Urbanization – Berlin - 18-22 November, 2012
Cameroon : soil contamination – case of Ngaoundere
  • Soils : deep ferralsols (more than 10m)
    • high content in iron (15 to 20 %) and clay minerals (40 to 60%),
     low CEC, acidic
  • UPA
    • as a results of rural exodus and seeking of income.
    • micro-projects in urban zones

  • Contamination
    • wide variety of potentially dangerous substances.
    • waste disposal : petroleum wastes
    • metals from domestic wastes

  • Research actions
    • research on soil and food contamination


                                            M.B. Ngassoum et al. – Université de Ngaoundere
                                          1st Global Soil Week – Urbanization – Berlin - 18-22 November, 2012
  Soil contamination (Ngaoundere)
                         • Organic contaminants (e.g.
                         hydrocarbons, PAHs) as a result of
                         uncontrolled management of oily
                         wastes (up to 500 mg kg-1)




• Metal contaminated soils
  (dumps, sewage)
•     ex:
                                 1st Global Soil Week – Urbanization – Berlin - 18-22 November, 2012
Suggestions
• Strong contrast between North and South
 but similar trends:
  • Consumption of the best agricultural land by urbanization

• How to think cities in a different manner ?
  • Strong demographic pressure and demand of soils
    • conflicts between food production and urban development
  • Urban planning: protection from sealing, encourage green areas

• What is sustainable UPA ?
  • Land tenure
  • Waste management – soil pollution
  • Adaptation to climate change
  • Urban soils : a sink for nutrient : how can we mine this resource ?

• Is it too late ?
  • A vast majority of soils in SSA are still multifunctional



                                            1st Global Soil Week – Urbanization – Berlin - 18-22 November, 2012

				
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posted:12/10/2012
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