The name Fanya chini literally means “throw it downwards” in Kiswahili. It consists of trenches and earthen ridges facing downslope. This intervention aims to reduce soil erosion because it breaks down long slopes into smaller sections. Hence, the speed of runoff will decrease and water can infiltrate into the soil between the bunds. It will result in a reduction of nutrient leaching and make more water available for crops.
Fanya chini is common in areas with 300-600 mm of annual rainfall on slopes of 1-25%. It is suitable for all types of relatively permeable soils (e.g. alluvial, red, laterite, brown, and shallow and medium black soil) but it doesn’t work very well with clayey soils or vertisols, since these are not permeable.
The excavated soil, obtained by digging trenches 50-60 cm deep and 60 cm wide, is placed on the lower side of the contour trenches, facing downslope. This is one of the most important distinguishing characteristic of Fanya chini compared to Fanya juu, where the excavated soil is relocated upslope. The presence of the bunds ensures the formation of microcatchments that concentrate the runoff coming from the land upslope of the bunds. Contour bunds works very well with tree planting interventions because it serves well as water harvesting technology. Indeed, this system is not only often used for the cultivation of annual crops such as Zea mays (corn), Eragrostis tef (teff) and Vicia faba L. (fava beans) but it can also be used for water demanding crops such as bananas, fruits and vegetables, that are usually planted where the runoff collects (e.g. immediately above or below the bunds).