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The results

Some of the results of the AEZ study are presented on this and the following three pages. They take two forms.

The first is a series of maps of agroclimatic suitability for 11 different crops in five regions: Central America, South America, Africa, Southeast Asia and Southwest Asia include only one crop, wheat, because this is grown on more than 75 percent of the land that is used for rainfed agriculture in the region.

The three maps on pages 18-20 show agroclimatic suitabilities for three crops, cassava, wheat and maize, assuming a low level of farming inputs. Similar maps exist for the other major crops, and are available for all developing countries (except those in Southwest Asia and China). Among other things, the maps indicate the lack of land suitable for growing rainfed wheat in almost all areas of the developing world except Southwest Asia. Maize and cassava, by contrast, can be grown widely in all regions except Southwest Asia.

Rainfed wheat in Southwest Asia

The second form that the results take is estimates of the extent of land available for growing each of the 11 crops in the developing world. The illustration on page 21 is a summary of the main results by region. The figures here include land of all suitability classifications except unsuitable and, again, are for low inputs.

The agroclimatic suitability map for cassava shows that the crop can be grown widely in all developing countries, except those in Southwest Asia. Similar maps are available for the other 10 crops included in the AEZ study. Very suitable areas for low-input cassava do not exist in Africa because of cassava mosaic. With mosaic-resistant, improved varieties and a high level of inputs, very suitable areas cover a large extent.

Wheat can be grown in few areas except in Southwest Asia, where it is grown on more than 75 percent of the land used for rainfed agriculture

This information is also available in more detailed formats, showing the extents of land available for growing each crop in each length-of-growing-period zone in each climate and in each country. These figures, unlike the agroclimatic suitability maps, are produced after appropriate adjustments have been made to allow for all the soil and related constraints.

The information is broken down into the three suitability classifications of very suitable, suitable and marginally suitable areas. Because potential crop yields are known for each classification, it is possible to estimate the potential crop production for each of the 11 crops in each developing country, for both low and high input levels.

Rainfed maize in Southeast Asia

Detail of the developing world map of agroclimatic suitability for maize (low inputs) for Southeast Asia.

Information which enables countries to make such calculations is available from FAO but more refined and precise climatic and soil inputs are needed before such results can be of practical use in land-use planning at the country level. National AEZ studies are dealt with in more detail in the section beginning on page 25.

Extent of land suitable for growing various major crops by region (all suitable or marginally suitable land under low or high inputs, million ha)

Extents of land suitable for growing the 11 major crops under rainfed conditions are shown for the five regions of the developing world.


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