IK Monitor Research (8-3)

Indigenous Knowledge and Development Monitor, November 2000

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Research, projects

Ethno-taxonomy of soils and their uses by the Iraqw of Mbulu and Karatu Districts, Tanzania
The Department of Soil Science at Sokoine University of Agriculture in Morogoro, Tanzania, is conducting research on the indigenous knowledge of soils in selected villages in the Mbulu and Karatu districts of the Arusha region of Tanzania. The current study focuses on the local soil classification system used by the Iraqw in these districts and attempts to identify the local diagnostic criteria for differentiating soil types as well as to explain how indigenous knowledge of soils has been applied to land use. The study was conducted by Associate Professor Balthazar M. Msanya and Dr Dismas Mwaseba of Sokoine University of Agriculture, from July 1997 to September 1999 with financial support from the Norwegian Agency for Development Cooperation (NORAD) under an agreement between Sokoine University and NORAD for a research programme. An earlier study (Msanya et al. 1998) had covered three villages. This study brings the total to seven. Data were collected using participatory rural appraisal (PRA) techniques with men and women farmers. These included group discussions, interviews, direct field walks and observation.

The Iraqw live in the Mbulu, Karatu, Hanang and Babati districts of the Arusha region in Tanzania. They migrated from Kondoa-Irangi in the central region of Tanzania in search of more land to accommodate their fast-growing population. In the research area, the Mbulu and Karatu districts, the Iraqw now make up 65 per cent of the population. Being traditional agro-pastoralists, the Iraqw operate a production system whereby manure produced by livestock is put on the fields, while the livestock are fed on crop residues. The main crops include maize, wheat, barley, beans, sorghum, sweet potato, Irish potato, and peas. The main livestock are cattle, goats, sheep and pigs. The high livestock densities typical in many areas of the districts have resulted in serious land degradation problems, particularly soil erosion, which is quite rampant.

The study produced detailed information which will be used for further ethno-taxonomical research at Sokoine University of Agriculture. What is important to report in this journal now is the system by which Iraqw farmers classify soil and use the land. This system's potential for incorporation into plans for sustainable land use will also be discussed.

The Iraqw soil classification system is based largely on surface characteristics, unlike the more technological classification systems, which focus on the whole soil to a depth of close to two metres (if there is no limiting layer) and which apply the concepts of soil profile and pedon characteristics. These well established systems of soil classification - such as the FAO-UNESCO and USDA Soil Taxonomy systems - have good reasons for using these concepts since plants depend not only on the surface soil for their growth, but also on the subsoil. Yet if we are serious about integrating local knowledge into development efforts, it is essential to start from an understanding of the ethno-taxonomy of soils.

Interviews and discussions with local people in Mbulu and Karatu revealed clearly that when they talk of a particular soil type they are referring to the soil as seen in terms of its surface characteristics. There are two basic principles behind the framework of the Iraqw classification:

Most soil names start with the formative element 'Hhaper' which literally means soil.
Hhaper is then followed by one or more adjectives which describe the type of soil in terms of the properties of its top layer. Examples of such properties include:

Soil colour. A typically red soil would be called Hhaper daāten, which simply means red soil (Daāten means red). Likewise, Hhaper bo'o means dark or black soil and Hhaper Sir-daāten means reddish brown soil.

Soil texture. A clayey soil would be called Hhaper tlei (tlei means clay). Hhaper sasagwan is typically a coarsely textured soil.

Soil workability (consistency). The soil type known as Hhaper bulgar bo'o is named for its hard consistency and difficult workability (bulgar). In the research area, Hhaper bulgar bo'o is associated with other characteristics as well, notably deep and wide cracking, which starts at the surface and extends to depths of more than 50 cm.
Presence of salts. The soil type Hhaper Hharki is a salty soil (Hharki means salt).

Water-logged conditions. Hhaper naari is a soil saturated with water (Naari means water-logged).

Other qualifiers:
Position in the landscape. Soils on valley floors and floodplains, for example, are generally called Hhaper baraduxa (Baraduxa means river valley or floodplain).

Occasionally subsoil characteristics are used. For example the soil type Hhaper baraduxa (valley-floor soil) is characterized by stratification which can be seen only when the soil is exposed. Another example is Hhaper busli Âwak, which forms deep and wide gullies that expose saprolite, a rock that weathers to a whitish colour.

Based on their knowledge of soil types, farmers decide the use to which a particular piece of land can best be put. For example, they attribute a high fertility status to Hhaper bo'o because it has a dark colour, feels humid because of its high organic content, and is easy to work with. Thus they use it for beans, sweet potatoes, bananas, maize, pigeon peas, wheat, sorghum, barley, wheat, sunflower, sugarcane, vegetables and all other crops. Another example is Hhaper bulgar bo'o. The Iraqw observe that this type of soil expands when wet, shrinks and cracks upon drying, is very sticky and difficult to till, and contains salts. They thus know that it is best suited for grazing. The farmers put soils which they judge to be unfit for agricultural production to other uses. For example, the coarsely textured soils are used for road construction, and the fine, sticky and powdery soils are used for plastering walls and making pots and bricks.

The study has revealed that farmers are familiar with the various soils in their localities. This confirms findings among farmers in other countries. Soil scientists and the managers of land resources should recognize the existence of local knowledge pertaining to local soils, and should incorporate this into their professional assessments of the suitability of soil and land. This would facilitate communication between the two parties for the purpose of developing plans for sustainable land use.

For more information, please contact: Dr Balthazar M. Msanya, Associate Professor, Department of Soil Science, Faculty of Agriculture, Sokoine University of Agriculture, P.O. Box 3008, Morogoro, Tanzania.
Tel.: +255-56 3380.
Fax: +255-56 3259.
E-mail: msanya@suanet.ac.tz

or: Dr Dismas Mwaseba, Lecturer, Department of Agricultural Education and Extension, Faculty of Agriculture, Sokoine University of Agriculture, P.O. Box 3002, Morogoro, Tanzania.
Fax: +255-56-3718.
E-mail: daee@sva.ac.tz

or: Dorothy J. Ole-Meiludie, Agricultural Officer, Ministry of Agriculture, Livestock and Cooperatives, Zonal Irrigation Office, P.O. Box 515, Morogoro, Tanzania;

or: Apia W. Massawe, Agricultural Research Officer, Ministry of Agriculture, Livestock and Cooperatives, Rodent Control Centre, P.O. Box 3047, Morogoro, Tanzania.

Reference
Msanya, B.M.; D. Mwaseba, D.J. Ole-Meiludie, G.G. Kimbi, A.R. Massawe and D.N. Kimaro (1998) 'Indigenous knowledge in soil classification: the case study of Mbulu and Karatu Districts in Tanzania', Journal of Management Development 10 (2): 237-260.