TRADITIONAL AFRICAN MIXED CROPPING SYSTEMS

The literature is rich in references to traditional systems in different parts of the continent, and only a few examples will be discussed. Most of them reveal a thoughful and sophisticated approach to the problems of sustainable production, whether referring to settled or to shifting agricultural practice.

Taking shifting agriculture first, several examples of farmers' awareness of declining yields following intensive cropping are given by Braun (1973).

Table 2 Examples of crop yield decline in shifting agriculture

Variations in the patterns of shifting agriculture are seen depending on soil fertility. Thus the 'Citimene' systems of Zambia entailed utilising the stored nutrients of a considerably larger area of Miombo Woodland than was actually cultivated, on soils of low fertility, whereas at the other end of the scale complex multiple-species gardens were developed by the Wachagga of Kilimanjaro on their eutrophic brown forest soils (Greenland, 1973).

The deep knowledge of the site requirements of many crops is particularly evident in the wetter zones, for instance in SE Nigeria, Zaire, and the East African mountains. Okigbo & Greenland (1976) note that the Medge of Zaire were known to be growing 80 varieties of 30 species of food crops in 1911, and that a close study of the cropping patterns indicated that local topography was cleverly used, with wide crowned trees suitably dispersed to control weeds and erosion, and light-demanding and shade-tolerant plants appropriately located. In Eastern Nigeria great complexity is shown in the placing of large numbers of different crops, sometimes more than 50 species, at various levels on artificial mounds (some 2.5m high) on hydromorphic soils. In Southern Nigeria, also, planted fallowing is practised, using, for instance, Acioa barteri, Anthonotha marcophylla & Gliricidia sepium. Such agroforestry and multiple cropping practices occur in many other parts of Africa, for example the Mango—Cashew-Coconut—Cassava pigeon pea associations of the Kenya Coast and mixed cropping on Ukara Island (Lake Victoria) and in Sukumaland. In the latter the influence of powerful cash markets in influencing cropping patterns is seen, in this case encouraging monocrops of cotton.

In many drier areas also crop mixtures abound, e.g. in the Hausa lands where Agboola (1981) notes that 156 crop mixtures had been recorded. These areas in the Sudan Zone are also notable for the deliberate retention of naturally occurring trees in the arable farming systems. The trees are retained for many purposes - for fruit, soils, medicines, fodder etc.; some of the better known are Acacia albida and Butyrospermun parkii, but Tamarindus indica, Borassus palm, Baobab, Parkia biglobosa and Balanites aegyptiaca are also noted (Yandji, 1981).

Animals are an essential part of many mixed cropping systems involving trees. These silvopastoral systems comprise at one end the traditional nomadic grazing systems of the drier zones throughout Africa, where range management principles are needed for stable production, to more synthetic systems developed from plantation agriculture. Examples of these include cattle under coconuts in Tanzania, and under oil palm in Cote d'Ivoire (Lazier et al, 1981).

Taungya systems for the establishment of planted forests were developed in Burma and India in the nineteenth century, and spread to other parts of the tropics thereafter. Their extent has varied with the need felt by governments to develop 'compensatory'¹ plantations in the national forest reserves.

Some of the most notable examples of successful taungya schemes, in the context of the national objectives referred to above, are to be found in Nigeria, Kenya, Tanzania, Uganda and Congo. Spears (1980) notes that 160,000 ha of plantations were raised in the forest reserves of the Kenya Highlands under the 'shamba'² system where licensed farmers grew maize, beans and potatoes before and after the trees were interplanted for 4-5 years. The conditions in the East African volcanic highlands are unusually favourable however. Ball (1977), notes that in 1975-76 there were over 24,000 'traditional' taungya farmers in 20,000 ha of forest reserves in Southern Nigeria. But he notes that 80% of the population was over 30 years of age, and similar situations where younger people are reluctant to enter into taungya agreements exist elsewhere in Africa.

Taungya is, of course, an imposed system rather than one developed indigenously, although it is an older practice in Africa than many systems developed by peasant farmers. It has undoubtedly depended for its success in some places on land hunger and poverty, and its social aspects have been examined critically by a number of writers, e.g. King (1968), leading to the new term 'agrisilviculture' which was intended to be a kind of 'taungya with a human face'.

Footnote_______________

¹ i.e. compensating for a lack of natural forests, for a lack of merchantable species in natural forests, or for a lack of expertise to manage exploited natural forests for a sustained yield of merchantable wood.

² the Kiswahili word used for the taungya system in East Africa.