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Kenya was chosen as a model study for national AEZ projects at the beginning of the 1980s. The kind of quantitative information that the AEZ methodology can provide is of particular use to countries with high population growth rates and with rapid development.
For example, food production varies greatly over the country, with the result that the government has to spend considerable amounts of foreign exchange on fuel and vehicles, in transporting food by road from one area to another. The government therefore asked for studies on the degree of self-sufficiency that can be attained in each district of the country. Where shortfalls occur, the AEZ methodology should be able to identify the nearest surplus-producing area able to supply the extra food.
The gravity of the population problem is illustrated by the rapidly worsening fuelwood situation. About 75 percent of Kenya's energy comes from wood, and total annual consumption was estimated at 32 million tonnes at the beginning of the 1980s. Sustainable fuelwood production from existing forests and plantations amounts to only about six million tonnes, and the shortfall is being met by utilizing forest stock.
By the year 2000, the situation will be much worse, with demand rising to an estimated 70 million tonnes annually. If this figure were to be met on a sustainable basis, a further five million ha of good arable land would have to be forested for fuelwood. How much of this land could actually be found by the year 2000, and what are the alternatives? It is hoped that the AEZ study will throw light on these issues.
Though the study began in the 1980s, including preparation of the land resources inventory, various difficulties have delayed the development of the basic crop, livestock and fuelwood productivity models until 1986, and documentation and publication of results until 1990. These delays not withstanding, it is believed that the efforts made have been very successful in producing a model and a study that will serve as a base for many other national studies.
Kenyan crop potentials, year 2000 (thousand tonnes)
The land resources data base was compiled from the information contained in the 1:1 million scale national soil map of Kenya by the Kenya Soil Survey, as well as from information on climatic resources specially inventoried for the study. The climatic resources inventory recognizes nine thermal zones, 15 length-of-growing-period zones and 22 growing period variability zones. The productivity model considers 65 crops (including pasture) and 31 fuelwood species.
Indications of the type of results expected from the Kenyan model have been provided by assessments undertaken by the International Institute of Applied Systems Analysis (IIASA). These revealed the critical need for soil conservation in Kenya (see box left) and the large potential that exists for expanding sorghum and millet cultivation compared to that of wheat.
The soil map of Kenya at a 1:1 million scale formed the basis of the Kenyan country planning AEZ project. Country planning projects usually required much more detailed information on soil and climate than the 1:5 million scale information used in the original AEZ study.
