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1.1.7 Fanya-juu Terracing
Based on the development of bench terraces over a period of time, and
known by its Swahili name, fanya-juu terraces are constructed by
throwing soil up slope from a ditch to form a bund along a contour (Figure
11). The trench is 60 cm wide by 60 cm deep, and the bund 50 cm high by
150 cm across at the base (Figure 12). Several of these terraces are made
up the slope following the contour lines. The distance between bunds
depends upon the slope and may be from 5 m apart on steeply sloping lands
to 20 m apart on more gently sloping lands.
Figure 11. Initial profile and later development of fanya
juu terraces (Critchley, 1991).
Similar terracing systems are found in many countries where the stones
from rocky slopes are used to build the bunds or terrace walls, often on
very steep slopes. Contour ridges may be combined with this system.
Through gradual erosion and redistribution of soils within the enclosed
fields, the terraced lands level off, forming the terraces. Soil and
rainwater are conserved within the bunds, and the bunds are usually
stabilised with planted fodder grasses. In addition, each farm using this
technology is surveyed to see if it needs a cutoff drain to be installed
in order to protect the terraces from surplus rainfall. The use of stone
terrace walls allows surplus water to pass through the bunds by
infiltrating between the stones and overtopping the walls.
Figure 12. Construction of the bund (Critchley, 1991).
Extent of Use
The technology is known from the Machakos District of Kenya, which is
hilly and subject to widespread erosion. Since the mid 1980s, the District
has achieved the installation of an average of 1 000 km of new fanya-juu
terraces each year, plus several hundred km of cutoff drains; 70% of the
cultivated land in the District is reported to have been terraced.
Between 1974 and 1991, the National Soil Conservation Programme in Kenya
prepared and implemented conservation plans on 925 000 farms. The rate of
compliance increased to 100 000 farms per year by 1991. A variety of
technologies were promoted through this Programme, including fanya-juu
terracing. Over 500 000 farmers were trained in conservation technologies.
Use of terracing is also reported on steeply sloping lands in Morocco.
Operation and Maintenance
Regular maintenance of the embankment is required
Level of Involvement
In Kenya, the implementation of this technology is normally undertaken
by self-help groups who work collectively on each others lands. Some
richer members of the community employ others to prepare the terraces
since family labour on its own is generally not adequate for constructing
these features. Self-help groups in Machakos consider soil conservation to
be one of their main activities.
The labour required for construction is estimated at 150 to 350 person
days/ha for terraces and cutoff drains. The cost of these structures is
Effectiveness of the Technology
In Machakos, crop yields have increased by 50% (or by 400 kg/ha) through
the use of fanya-juu terraces.
This technology is suitable for marginal or wetter zones of 700 mm
annual rainfall or above. Soils should be deep. The technique is suitable
for use on slopes of less than 5% to 50%.
There is effective control of erosion. Where a whole catchment has been
conserved there is an improvement in streamflows with consequent benefits
for a village water supply.
The technology generally results in a reliable increase in crop yields.
The technology is costly in terms of labour. Unprotected bunds, which
have not been planted with grass, are prone to erosion.
This technology has fitted well into culture of the self-help groups
present in the areas of application to date, and reinforces their emphasis
on full involvement of the community in freshwater augmentation efforts.
The technology has already been established in the area and, therefore,
there was no cultural resistance to it.
Further Development of the Technology
Application of this technology in other areas needs to be further
examined as there were special conditions in the Machakos District of
Kenya which enabled it to succeed.
Critchley, W. 1991. Looking After Our Land, Soil and Water
Conservation in Dryland Africa, Oxfam, London, 84 p.
Lee, M.D. and J.T Visscher 1990. Water Harvesting in Five African
Countries. IRC Occasional Paper No. 14, 108 p.
Pacey, A. and A. Cullis 1991. Rainwater Harvesting. The
Collection of Rainfall and Runoff in Rural Areas. Intermediate Technology
Publications, London, 216 p.
Eriksson, A. (Editor) 1992. The Revival of Soil Conservation in
Kenya. Regional Soil Conservation Unit, SIDA Report No 1, 30 p.