Transcript Indigenous soil and water conservation methods in Africa.

Indigenous soil and water
conservation methods in
Africa.
Presented by:
Becky Humphrey
(MSc Water Resources)
Introduction
What is indigenous knowledge?
• ‘The knowledge used by local people to
make a living in a particular environment.’
• ‘A body of knowledge built up by a group
of people through generations of living in
close contact with nature.’
Indigenous knowledge is based on:
• Adapting to the specific requirements of
local people.
• Creating and experimenting with methods
to suit local environmental conditions.
• The incorporation of outside influences,
together with inside innovations.
• Cultural knowledge
• Consideration of social, political, economic
and spiritual aspects of the local lifestyle.
Soil and Water Conservation
• Need to take holistic approach in dealing
with any aspect of environmental
conservation.
• Soil processes and runoff processes affect
each other, therefore it makes sense to
use methods which incorporate both
factors.
Types of SWC methods
•
•
•
•
•
•
•
•
•
Earth / stone bunds
Bench / step terraces
Improved planting pits
Micro basins
Pitting
Modification of contour ridges
Mulching
Contour stone bunds
mounds
Types of SWC methods (continued)
•
•
•
•
•
•
•
•
Strips
Vegetation barriers
Grass strips
Drainage ditches
Basin irrigation
Ridge cultivation
Raised bed cultivation
Hedge barriers
Focus on Africa
• Long history of traditional farming
methods.
• Diverse landscape between & within
individual countries.
• Inhospitable terrain.
• Harsh climatic extremes.
• Usually very hot and dry, but problem of
flash floods during rainy season also
exists.
Case Studies
•
•
•
•
The Dogon Plateau, Mali
Southern Zimbabwe
Upper East Region, Ghana
Harerge Highlands, Ethiopia
Traditional SWC techniques on the
Dogon Plateau, Mali.
Area Characteristics
• Agricultural economy (cereal cultivation &
market gardening)
• Subsistence farming with limited cash
crops
• Main crops are Sorghum & Millet
• Main garden crops are onions & tomatoes
• Rainfall low & variable
Problems
• Droughts lead to poor crop production
• Heavy rainfall leads to severe soil erosion
and pan formation
• Soil has poor structure
• Steep hillsides
• Area densely populated
• Only 10-15% of plateau is arable land
Development of indigenous
methods
• Hillsides originally populated because
Dogon people hid from invaders in caves
• Despite the fact that this is no longer an
issue and good arable land exists
elsewhere, population is concentrated
here because of traditional values and
cultural reasons
• SWC necessary for survival
Traditional SWC techniques
•
•
•
•
•
•
Cones / mound making
Terracing of fields and hillsides
Stone lines
Bunds / low stone walls
Square basins
Planting holes
More unique methods
• Stalks left after harvest are cleared away
and then laid on the soil surface in bands
to reduce soil erosion.
• When the organic matter eventually
decomposes it provides another benefit
through increased soil fertility due to
added nutrients
The Future
• Labour shortages due to migration are
threatening SWC techniques
• Land tenure problems
• However, increasing role of women &
assistance through participatory
development is promising.
Indigenous SWC in Southern
Zimbabwe
• SWC has played important role in
development of smallholder agriculture.
• Long tradition of indigenous farming
methods threatened by mechanisation and
political intervention
Historical SWC
• Farming based on livestock & shifting cultivation
• Livestock = food, clothing, transport & manure (also
social status) but not enough draught power.
• Main crop was Finger Millet.
• Bush clearance led to cultivation of 3-10 yrs, then fallow.
• Wetlands also cultivated (ideal during drought)
• Hunting & gathering
• Traditional values ensured conservation (esp. water &
trees)
• Low population & limited tools
• Use of intercropping, mulching, bunds & ridges.
The Plough
• Plough introduced by white settlers in late
19th century
• Adopted by local farmers on large scale
1920-1940
• Indigenous farming saw many benefits in
increased production
• Erosion occurred on large scale (rills &
gullies) & land took longer to recover from
fallow.
Government Intervention
• 1930 onwards: erosion became serious problem
• Colonial government forced building of contour
ridges and lowering of stocking rates
• Also prohibited wetland use
• Unpopular, esp. as ridges unsuitable for dry
climate
• Shifting cultivation & bush fallow ended
• Use of plough encouraged
• Poorly constructed ridges increased gully
erosion
The Liberation Struggle
•
•
•
•
1976-1980 = liberation struggle
Farmers encouraged to abandon ridges
New government could not enforce SWC
Farmers associated SWC with ridge
building & therefore opposed to SWC
• Village development committees
established
• Gradually, need for SWC realised
Problems
• Attitude based on historical contempt for
local knowledge in favour of Western
mechanisation
• Previous indigenous SWC methods
inappropriate due to increased population
density
• Confusion over land rights
Solutions for the future
• 2 projects: Food Security & Conservation
Tillage
• Incorporation of traditional SWC methods
• Participatory approach has led to
encouraging response
• Membership of farmer clubs increased
• Particular interest in garden crops & SWC
The Yaba-itgo system in Upper
East region, Ghana
Area characteristics
• Savannah grassland belt
• Erratic rainfall May-September, but often lull in
growing season
• Dry & dusty winds during dry season
• Sandy soil with little OM
• Rain fed crops (millet), subsistence farming
• Garden crops during dry season
• Small livestock
Problems
• Farmers cannot afford livestock & equipment for
ploughing
• Renting land discourages SWC
• Women deterred from SWC, despite being good
at it
• Isolation during rainy season
• Exploitation by middle men
• External intervention usually abandoned by
farmers
Yaba Itgo: ‘Grandfather’s way of
doing’
• Wide range of SWC methods
• Usually aim to conserve moisture on steep
slopes
• Also encourage runoff if area prone to
flooding
• Methods never used in isolated way
• Clear division of labour between gender
and age
Erosion Control
• Dependant on household labour
availability
• Stone bunding
• Contour tillage
• Border grasses
• Strip cropping
• terracing
Drainage control
• Dependant on communal labour
availability
• Focus on flood risk due to cash crops
• Land smoothing / levelling
• Graded furrows
Recent Changes
•
Driving force changed from cultural reasons to
production incentives
1) SWC blended with agronomic practices e.g.
mixed cropping, cultivation of groundnuts,
mulching
2) Bush burning greatly reduced, so soil fertility
improved
3) Some incorporation of live fencing & use of
livestock for ploughing (opposed still by
women)
Indigenous SWC techniques of the
Harerge Highlands, Ethiopia
Area characteristics
• Hilly terrain (low-moderate relief)
interspersed with sloping valleys
• High population density
• Stony soil, rocky outcrops
• Erratic rainfall regime (2 seasons)
• Erosive tropical storms
Problems
•
•
•
•
•
•
Lower & more unreliable rainfall
Decline in soil fertility
Shortage of fertilizer (organic & inorganic)
Shortage of livestock for ploughing
Prevalence of pests & disease
Migration of farmers to urban areas
Traditional SWC methods
• SWC methods have increased due to decline in
agricultural productivity
• Use wide range of agronomic, biological &
mechanical measures
• Knowledge has evolved over time in response to
local needs
• Crop rotation, intercropping, cactus / grass strips
• Focus on increased soil fertility, reduced erosion
& diversification
Stone bunds
3 benefits:
1) Remove stones from field, easier to
plough
2) Slows runoff & traps moisture
3) Stops erosion & traps nutrients
Soil bunds also used:
• Not as stable but easily moved / rebuilt
• Can evolve into terraces if left to mature
Outside intervention
Development programs have gone wrong:
• Farmers not consulted
• Large scale engineering as opposed to
gradual build up when needed
• Livestock / human passage ignored
Disadvantages of traditional SWC
• Most methods require a high level of
manpower, but many younger members of
families are leaving rural locations in
search of more prosperous employment
• Often cannot be carried out on a large
scale
• Need for some inclusion of modern
methods
Advantages of indigenous SWC
• Local people have managed the land for
generations and know what is needed
• Low cost
• Simple methods that can be learned
quickly
Conclusions
• Indigenous methods of SWC are long
established and work well
• However, their success is largely affected by
political factors and intervention by developed
countries, NGO’s etc.
• There is an ever increasing need for cooperation
and understanding between researchers,
engineers, local farmers etc.
• Some cultural traditions & gender issues need to
evolve in order for indigenous SWC to survive in
Africa.
The importance of indigenous
knowledge
‘Incorporating indigenous knowledge into
research projects can contribute to local
empowerment and development,
increasing self-sufficiency and
strengthening self-determination.’