The Matengo have cultivated steep slope fields for more than a century using their original soil conservation system. This system is a two-year rotation that includes a short-term grassland fallow. The field lies fallow without cultivation during the early rainy season at the first year. The grasses are cut down and the dry shoots are gathered up in lines forming a grid on the field that is then covered with topsoil in a square. The ridges from the grid, thereby producing many well-ordered pits over the whole field. The pit can function as a buffer and controls run- off by allowing rainwater to stand. Although the pit may break if the precipitation of an intense rain is beyond the capacity of buffer, the ridges are protected consistently because the water in pit can be efficiently led downward along the buried shoot bundles in the soil. At the beginning of the next rainy season, maize is sown on the ridges. Because the buried shoots are decomposed during this rainy season releasing nutrients of the maize, subsurface drainage is lost. The pit functions as a small sedimentation tank until the pit is filled with soil. Thereafter, because the field is covered with well- grown maize, the surface soil is again protected from runoff, thus conserving the topsoil and their fertility on steep slopes throughout a year. This area is also famous for coffee production, and the high cash income from coffee has economically sustained this farming system and the society.
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