STEPHEN NANTHAMBWE

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Environmental Consequences of Current Southern
Africa Food Production Land Degradation,
Greenhouse Gas Emissions, Water Resources
Depletion and Biodiversity Impacts

• STEPHEN NANTHAMBWE
• GECAFS Issues Identification Workshop in South
  Africa
• Johannesburg
• 10th May 2003

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South African Countries
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Food Production Challenges in the SADC region

• Poverty lowest per capita in come in the
  world,40 202 million people in the region live
  below US1.0 a day. More people to feed
• Limited access to production enhancing
  technologies machinery, fertilizers and land
  improving technologies in general.
• Over dependency on rain fed agriculture,
  underdeveloped irrigation potential (about 4.5
  of total cultivated land ).
• Dominance of smallholder subsistence farming
  (crops and animals)
• Recurring droughts and floods

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Resource Endowment of the region

• 9.2 million square kilometers of land area only
  5 cultivated.
• Very rich biodiversity both flora and fauna
  inside and outside protected areas.
• 263 million hectares of forest land representing
  29 of total SADC land area
• Large areas of wetlands including 29 Ramsa
  designated sites (wetlands of international
  importance) covering a total area of about 13.3
  million hectares
• Costal and inland water resources supporting
  various fish species

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Food Production systems

• Small scale, traditional unimproved management
  levels mainly for subsistence, much reduced
  fallow periods.
• Small large scale commercial agriculture
  subsector with improved management
• Irrigation mainly on high value crops - mostly
  sugar, tobacco
• Shifting cultivation, slash and burn still being
  practised in some countries where land is not
  limiting
• Encroachment of agriculture into environmentally
  fragile areas due to greater competition for land
  from different users.
• Livestock farming dependent on natural pastures

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Environmental Consequences

• Food production activities have many
  environmental consequences which can avoided and
  minimised through improved management
• The environmental impacts include
• Land Degradation
• Greenhouse gas emissions
• Water resource depletion
• Biological diversity degradation

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Land Degradation

• Land degradation caused by food production from
• Overgrazing causing deterioration in quality and
  quantity of upland and riparian vegetation.
• Concentration of fishing communities exerting
  pressure on land
• Erosion caused by agriculture is a major cause of
  land degradation- clearing of original
  vegetation, cultivation of land not suitable for
  agriculture and using inappropriate technologies
• Accumulation of salts (salinization), water
  logging arising from irrigation of poorly drained
  soils
• Soil compaction arising from use of heavy
  machinery (plough, hoe pans that restrict water
  movement and root development)

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Soil Erosion

• Recognised as a very serious problem in Southern
  Africa
• Very few studies to assess severity at national
  levels
• Chakela (1981) estimated the rate in one valley
  in Lesotho at between 100 and 200 tonnes per
  square kilometer per year
• Stocking(1986) estimated the rates of soil
  erosion for land under different tenure systems
  in Zimbabwe
• commercial farming under grazing - 3 tonnes/ha/yr
• communal land under grazing - 75 tonnes/ha/yr
• commercial arable lands - 25 tonnes/ha/yr
• Communal arable lands - 50 tonnes/ha/yr

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Soil Erosion

• In Malawi erosion is estimated to contribute
  between 4 and 11 of loss of crop yields (World
  Bank 1992)
• In general soil erosion is a very serious
  environmental problem that leads to declining
  productivity, destruction of infrastructure and
  sedimentation of water bodies.

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Soil Erosion on cultivated land
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Water Resources Depletion

• Agriculture is the major use of water
  irrigation. A great proportion of the population
  in SADC relies on groundwater for basic needs,
  agriculture and livestock watering.
• By 1995 irrigation accounted for ( 36,130 MCM)
  60 of total regional water demand (60,515 MCM).
  Livestock watering 2
• It is estimated that by 2020 the regional water
  demand will increase by 93 over the 1995 demand.

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Water Resources depletion

• The effects of cultivation on water resources
  have not widely been investigated (SADC 2002)
• Clearance of vegetation results in an increased
  runoff from watersheds. In Zambia 95
  deforestation of woodlands increased annual flows
  by 56 to 74

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Water Resources depletion

• Clearing 75 of wet miombo woodlands in Zambia
  and temporary convention to subsistence
  agriculture had the following effects
• surface runoff increased by 10-18 percent
• peak flows increased
• annual evapotranspiration was reduced and
  baseflow increased

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Water Resources depletion

• The near-surface water table found in dambos
  (wetlands) enables localized irrigation from
  shallow wells throughout the year.
• Pollution and eutrification of water bodies from
  agrochemicals and solid sediments

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Fish farming
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Greenhouse Gas Emissions

• Greenhouse gases associated with food production
  are Carbon dioxide from burning of fossil fuels
  and decaying of organic matter, methane from
  wetlands and ruminant animals and nitrous oxide
  from fertilizers.
• Quantification of GHG emissions from agricultural
  sources is not readily available.
• Contribution from fossil fuels associated with
  food production likely to be low as systems are
  less mechanized.

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Greenhouse Gas Emission

• Crop residue burning commonly practiced in most
  countries.
• Nitrogen is limiting in most soils and use
  nitrogen fertilizers is common
• Contribution of ruminants, methane as a byproduct
  of their digestive processesSADC has about 47
  million herds of cattle and considerable numbers
  of sheep and goats.

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Biodiversity

• SADC region is rich in biodiversity, however it
  is increasingly being threatened by human
  activities such as land use conventions, bad
  farming practices, over fishing and poaching
  leading to extinction of other species.
• Agriculture has been blamed to threaten wild
  biodiversity due to its seemingly high appetite
  for land and water.
• Reserved areas and wetlands which are pools of
  biodiversity are being encroached due to
  competing demands on available lands.

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Biodiversity

• In SADC region forest cover is estimated to be
  declining at the rate of between 0.75 to 2.2
  per annum. Angola has the lowest and Malawi the
  highest deforestation rates.
• Shifting cultivation and bush fires threaten wild
  biodiversity.
• Opening land for agriculture, settlement etc lead
  to loss of habitat for wildlife.
• Potential threat of GMO to biodiversity

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Conclusion

• Food production systems that co-exist with wild
  biodiversity, limit degradation are possible
• Examples include various agroforestry, minimum
  tillage technologies that are being practiced in
  some parts of the region.
• Require information on extent, potentials and
  limitations of land based resources and potential
  impacts of different management practices.