|Traditional Storage of Yams and Cassave and its Improvement (GTZ)|
Cassava was introduced to Africa in the 16th century and became established at various locations on the continent in the subsequent centuries. However, not until the beginning of the 20th century did cassava become extensively widespread and find a permanent home in numerous small farm systems. In some cases, cassava clearly took over from other staple foods e.g. bananas in East Africa and maize and sorghum in southern parts (LYNAM, 1991).
In Africa, but also on other tropical continents, cassava is mostly grown by small farmers. In Africa, only 10% of production reaches the market; 90% is cultivated as food for the producers themselves. Cassava provides central benefits particularly for subsistence-oriented farms from an economic aspect.
Cassava has a potential tuber yield of 70 tons per hectare and with this, has the highest output per unit area among all staple foods providing starch (COCK, 1985). Decisive for subsistence-oriented small farmers who avoid risks is the ability of cassava to provide secure yields of 7 - 9 tons of roots per hectare even on marginal and acid soils and under unreliable precipitation conditions (ONAYEMI, 1982). In addition, the annual fluctuations in the yield of cassava are among the lowest for all food crops (HAHN, 1987).
In comparison to other roots and tubers, the labour productivity of cassava is very high. For a yield of 10 tons per hectare, a labour input of approx. 120 days (manual phase) can be estimated (COCK, 1985). This corresponds to about one quarter of the work input required to produce the same quantity of yams.
After the plants have closed their leaves, cassava can be left to itself. On the one hand, a contribution is made here to evening out peak seasonal work (HAHN, 1987). On the other hand, this encourages the seasonal migration of male labourers in search of an income, without endangering the production of cassava.
Production input, e.g. fertilisers, plant protection and propagation, is very low. Fertilisers can be completely dispensed with without fear of losing any part of the yield (COCK, 1985).
The economic features and modest requirements of the plant are the reason for it being called a "starving plant". Cassava is able to provide secure yields on marginal sites and under unfavourable weather conditions which cause crop failure for other plants.