Soil conservation options in the Savanna of West Africa: new approaches to assess their potential International Institute of Tropical Agriculture– www.iita.org Birte Junge Overview of activities and results of the BMZ/GTZ-Project conducted at IITA from 2005-2008
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Soil conservation options in the Savanna of West Africa: new approaches to assess their potential
Soil erosion in Nigeria,Land use intensification in pilot villages varying in length of cropping season and linkage to erosion features,Impact of soil conservation technologies in the Savanna of Nigeria, Benin, and Ghana assessed,New approaches for on-farm monitoring of short and long-term benefits from soil conservation technologies developed and tested
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Soil conservation options in the Savanna of
West Africa:
new approaches to assess their potential
International Institute of Tropical Agriculture– www.iita.org
Birte Junge
Overview of activities and results of the BMZ/GTZ-Project
conducted at IITA from 2005-2008
- Introduction
Term: Soil
Problem: Soil erosion in Nigeria
- Activities and Results of studies on
1. Remote sensing + GIS
2. Adoption of soil conservation technologies
3. Measurement of erosion
- Conclusions
Outline
Soil conservation (Gibbons 1988)
- includes whole program of studies for preventing + reducing soil degradation
Introduction
Soils in West Africa
- Age: old
- Material: sand / gravel / clay
(Lal 1995)
Luvisol
Ah
2 Bt
3 Ct
Soil degradation (Oldeman 1991)
- Soil erosion by water
- Soil erosion by wind
- Chemical deterioration
- Physical deterioration
Problem: Soil erosion in NigeriaIntroduction
Federal Surveys of Nigeria (1992)
General Soil Erosion Map of Nigeria 1:6,000,000
Sheet erosion
Gully erosion
Wind erosion
Output 1:
Land use intensification in pilot villages varying in length of cropping season
and linkage to erosion features established.
Pilot villages:O1: Methods
Remote sensing data:
Aerial photograph IKONOS QuickBird
Date 1962/1981 2000 2005/06/07
Spatial resolution (panchromatic image): 1 m 0.6 m
O1: Methods
Maize
Millet / Sorghum
Cowpea
Interpretation:
Land use/land cover
O1: Methods
Compound
O1: ResultsBadume: Kano State
Change of village area
Today:
NO land available any more
Total Increase
4022000
An. increase
2651949
Year
+ 137
+ 2.7
Area (ha)
O1: ResultsKayawa: Kaduna State
Change of farmland
1962
Cowpea
Maize
Sept. 2000Dec. 2006
+ 216.4
Change
49.7
1962
+ 20.5286.6266.1Arable land (ha)
Change20062000Year
Gadza:
Change of settlement, forest, uncultivated land
O1: Results
Oct. 2000Jan. 2005
Sorghum Millet Fallow
Rice
- 26.577.5104.0Uncult. Land (ha)
- 4.88.513.3Tree, shrub (ha)
+ 0.31.51.2Settlement (ha)
Change20062000Year
Land use intensification:
O1: Summary
- Reduction, elimination of fallow
- Deforestation
- Decrease of uncultivated areas in surroundings
- Expansion of settlements areas
- Expansion of villages areas
- Expansion of farmland
Rate of increase higher in former times
No expansion possible any more today (land scarcity)
Conversion of other land use types into farmland
O1: ResultsBadume: Kano State
Present gully erosion
2000
Measurement:
7708Soil loss (t)
1.2Area (ha)
2006Year
2006
Calculation:
7.245.137.9Area (ha)
Increase20062000Year
O1: ResultsBadume: Kano State
Future gully erosion
2006
Depth line
Gully border 2006
Gully border 2016
Gully border 2026
Estimation:
R = 0.36 (A)0.46 (P)0.20
R = Rate of headward advancement (m yr-1)
A = Tributary watershed area (ha)
P = Annual precipitation (mm)
Morris and Fan (1997)
Badume: R = 0.5 m yr-1
Year 2006 2016 2026
Area (ha) 4.3 5.1 5.9
1962
O1: ResultsKayawa: Kaduna State
Sheet erosion
Year 1962 2000 Change 2006 Change 2016
Sheet erosion (ha) 7.9 25.6 +17.7 32.3 + 6.7 42.3
Annual rate (ha yr-1) 0.5 1.1
2000
2005
Gadza: Niger State
Gully erosion
O1: Results
River
Settlement
1 m
Year 2000 2005 Change 2015
Gully length (km) 12.8 58.4 + 45.6 91.2
4184Soil loss (t)
1.2Area (ha)
2006Year
Measurement:
Eglime: Dept. Mono
Gully erosion
O1: Results
2007
Cotton
Gully
Year 1982 2000 2007 Change 2017
Gully length (km) ? 4.4 42.4 + 38.0
Gully area (ha) 2.3 18.7
Soil erosion:
O1: Summary
- Reduction of arable land
Decrease of crop production
- Reduction of uncultivated area in surroundings of farmland
Decrease of grazing land
- Increase of gully and sheet erosion in Badume, Kayawa, Gadza, Eglime
Rising conflicts among various users deriving from competition
for limited resources in the future
Use of thematic maps:O1: Conclusions
Agenda 21 (UN 1992)
- more effective use of land and natural resources
by improved planning, management and evaluation systems
Nigerian Department of Agricultural Land Ressources, Abuja
- Implementation of appropriate policies
Environmental Management Support System
- Database for inventory of natural resources
Problems: missing equipment, no trained staff, …
Use of thematic maps:O1: Conclusions
Land use planning
Soil conservation
- Field maps for installation of
soil erosion control measures
Tree, Shrub
Vetiver
Stone barrier
Badume
- Reservation of areas
with fertile soils for farming
with degraded soils for reforestation, settlements
with minerals for mining
Publications:
O1: Outcome
Farmer Field Hour:
Junge B., Alabi T., Sonder K., Abaidoo R., Chikoye D., Stahr K. (2008):
Remote sensing and GIS for monitoring changes of land use/land cover and environmental degradation
in different agroecological zones of West Africa
Manuscript for Int. J. Remote Sensing
Junge, B., Abaidoo, R., Chikoye, D., Alabi, T. & Stahr, K. (2006):
Monitoring of land use intensification and linkage to soil erosion in Nigeria and Benin.
Conference proceedings, Deutscher Tropentag (DTT), 11-13 October 2006, Bonn, Germany
- Presentation of study on land use change
and soil degradation
- Discussion of possible soil conservation
measures
Kayawa 31 Oct. 2007
Output 2:
Impact of soil conservation technologies in the Savanna of Nigeria, Benin,