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TERRACING Introduction effective means of retaining soil moisture & nutrients if designed and constructed properly and if they are well maintained reducing slope angle facilitates cultivation etc. erosion is function of slope degree & length
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TERRACING • Introduction • effective means of retaining soil moisture & nutrients if designed and constructed properly and if they are well maintained • reducing slope angle facilitates cultivation etc. • erosion is function of slope degree & length • measures which reduce either or both of these will reduce erosion
Types include:- • Steep back-sloped (fany-juu) • Bench terraces • Channel terraces • Broad-based terraces • Zingg conservation terraces
Constructed to be level from front to back - ideal for semi-arid areas. • If terrace is constructed & maintained well, all the rain can be retained assuming there is a bund / dyke at edge to prevent water running over the edge. • Alternative name is the "retention terrace". • constructed by making "steps" in the hill side in one operation • commonly used for irrigation schemes or plantation crops (e.g. coffee) • if levelled by hand, they are a LOT of work.
Channel terraces Used for leading water away from field - not so suitable for very dry areas - except on very impermeable soils or on steep slopes
Other types of terraces Potential for erosion on foreslope if not well maintained with vegetation. Toe drain prevents the problem referred to when discussing vegetated strips
Zingg / Conservation terrace • Ideally constructed with earth-moving equipment - not usually available in DCs or are too expensive. • Discussed in session on water harvesting.