Image: Hanspeter Liniger
The name Fanya juu means “throw it upwards” in Kiswahili and it is very similar to fanya chini since it consists of terrace bunds and ditches along the contour. The goal of contour bunds is different considering the environmental conditions of the areas where they are used. Their aim in semi-arid areas is to harvest and conserve rainfall, whereas, in sub-humid zones, contour bunds are constructed to discharge excess runoff. However, the main purpose is to prevent water and soil loss and to make conditions more suitable for plants to grow. Fanya juu is suitable for slopes of 5-20%, similar to the ones that characterize fanya chini interventions.
The preferred distance between the terraces depends on the slope and soil depth. The earth bunds are built by digging a trench, of, typically, a depth of 50-60 cm and a width of 60 cm, and by relocating soil upslope in order to form the bund. It is recommended to include cross-ties every 10 m: small amounts of soil that are at a 90-degree angle to the bunds and prevent water run-off to catch speed along the earth bunds. This intervention is also characterized by the presence of a small ledge between the ditch and the bund in order to prevent soil from sliding back. The bunds are often stabilized with fodder grass in order to improve soil trap and water infiltration. The species most often used in drier zones are Pennisetum purpureum (Napier grass or Uganda grass) and Panicum coloratum (also known in southern Africa as “white buffalograss”) and the harvest can be used as fodder for livestock. Also fruit trees (e.g. citrus or bananas) can be planted either immediately above the embankment or below the ditch, where runoff tends to concentrate. Even though, from a technical point of view, the techniques of fanya juu and fanya chini are very similar, fanya juu requires more work than fanya chini. Over time, fanya juu terraces can evolve in level bench terraces due to tillage or soil erosion.
Fanja juu technique rapidly spread during the 1970s and 1980s and it is well known throughout Eastern Africa.