A Rational Approach to the Selection Of Crops for Areas of Marginal Rainfall In East Africa

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Date
1965
Authors
Dagg M.
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Abstract
The steadily increasing pressure on the land in East Africa has intensified the need to study the principles governing the selection of crops for areas of low and erratic rainfall and the need to delineate areas suitable for different crops. The traditionally accepted climatic characteristics of rainfall and temperature are not particularly suitable for discussing vegetation patterns and they are certainly not adequate for defining which crops will be suitable for specific areas. The system of climatic classification introduced by Thornthwaite (1948) represents a considerable advance on the earlier methods in that it uses monthly rainfall and evaporation data to define periods of water surplus and deficit and it remains probably the best system for the large-scale mapping of climates. The precise method of estimating evaporation proposed by Thornthwaite has distinct limitations when applied in the tropics, but using the more realistic Penman (1948) estimate of evaporation, the area around the East African Agriculture and Forestry Research Organization's headquarters would be defined as being a "Dry sub-humid" climate with a water surplus in the winter months. This is a good description of the local climate at Muguga but it does not really help a great deal in deciding which crops to grow.
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East African Agricultural And Forestry Journal, XXX (3), p. 296-300