Article 3: Soil Types
(Source: infonet-biovision: CC: BY NC SA)

Andosols (young volcanic soils)
Andosols occur in areas with steep slopes and high-rainfall. By rainfall over 1000 mm per year, andosols are exposed to excessive leaching. Andosols are porous, have a high water-storage capacity and a low bulk density. They are also acidic (low pH) due to the high leaching of soluble bases and to the high levels of Aluminium (Al). These conditions favour P-fixation, making it no longer available to the plants. To improve agricultural production liming and the use of fertilizers is necessary. Andosols are highly susceptible to erosion as they mostly occur on steep slopes. In these areas, they are mainly used for tea, pyrethrum, temperate crops and dairy farming.

Nitisols
Nitisols occur in highlands and on volcanic steep slopes, for example in the central highlands of Kenya, some areas of the Ethiopian highlands and around Mts. Kenya and Kilimanjaro. They are developed from volcanic rocks and have better chemical and physical properties than other tropical soils: they have a good moisture-storage capacity and aeration; the organic matter content, the cation exchange capacity and the percentage base saturation range from low to high. Most nitisols are acidic (pH < 5.5) due to the leaching of soluble bases.
Nitisols often have a high clay content (more than 35%). They are the best agricultural soils found in the region. They are intensely used for plantation crops and food production (e.g. banana, tea and coffee).
For optimal agricultural production, nitosols need the use of manure and inorganic fertilizers. To protect these soils from erosion, soil conservations measures are essential.