|Resource Management for Upland Areas in Southeast Asia - An Information Kit (IIRR, 1995, 207 p.)|
|3. Soil and water conservation approaches|
A ridge terrace consists of a furrow and ridge, constructed along the contour on sloping land (usually less than 15%). Its purpose is to control soil loss and trap water. Grasses and legume trees are usually used to stabilize the ridge, but fruit trees, banana and cassava are also commonly used. During the wet season, the furrow fills with sediment and farmers put this back on to their land. Variations on ridge terraces include alley cropping, contour tillage and sloping agricultural land technology (SALT)
· Effectively controls runoff and erosion on moderate slopes.
· The furrow behind the ridge traps sediment and nutrients.
· Relatively low labor inputs are required compared to bench terracing.
· There is minimum disturbance of soilparticularly important on shallow upland soils.
· Less effective in controlling erosion than bench terraces
· Takes time and labor to establish a stable ridge.
· Needs proper maintenance, since the ridge can break, channel runoff and result in rills.
Factors affecting adoption
· If livestock are present, grasses or tree legumes can be grown on ridges to provide fodder.
· Intense rain can wash away ridges, especially in the first two years when they are not firmly
· Ridges on sandy or unstable soils do not stand up well.
Bench terrace construction on state-owned land is prohibited in some countries, so ridge terraces are the next best alternative. This also relates to the tenure problem (Indonesia).
Farmers with limited labor appreciate the relative ease of constructing ridge terraces compared to bench terraces.
Grass and other fodder species grown on the ridges are sometimes seen as competing with food crops and are removed, thus weakening the ridge.