Brief overview
Drylands are generally subject to climate regimes that are not highly favorable to crop production. Low total rainfall and high variability in rainfall patterns present difficult challenges for growing crops. Nevertheless, local populations depend on these lands for producing food.
Map description (Map 13)
In a spatial analysis of food production data for Latin America, the International Food Policy Research Institute (IFPRI) developed nutrient balance maps for the major Latin America and the Caribbean cereals: wheat, rice, maize, and sorghum. These maps were aggregated to one soil nutrient balance map for lands under cereals and combined with information on cereal yield trends for the years 1975 through 1995. A final map was created that superimposed the yield trend and nutrient balance maps to arrive at a soil fertility map of potential trouble spots and bright spots. In Map 13, we have clipped the IFPRI map to show only drylands of Latin America. On this map, potential bright spots are defined as stable or increasing yields with positive or only slightly negative nutrient balances (0 to –25 kg/ha per year). Potential trouble spots are identified as areas where yields are decreasing and nutrient deficits are greater than 25 kg/ha per year, or where yields are stable but the nutrient deficit is greater than 100 kg/ha per year.
This soil fertility map in cultivated areas of Latin America identifies a few potential bright spots in drylands, in Venezuela, Ecuador, Peru, Chile, and Brazil. Some negative trends show up most prominently in Mexico, Bolivia, Argentina, and Brazil. Potential trouble spots are found in Mexico, Colombia, Venezuela, Bolivia, and Argentina. These trouble spots may have experienced either decreasing cereal yields and high soil nutrient deficits or, stable yields but very high nutrient deficits.
Caution should be used when interpreting these classifications. For example, the bright spots in Venezuela generally coincide with places of large application of fertilizer with high yields and excess nutrients in the soil. Field reconnaissance and further analysis must be used to verify specific conditions at each location.
Map descriptions (Maps 14 and 15)
In Map 14, the International Food Policy Research Institute (IFPRI) combined agroclimatic, slope, and irrigated area data with agricultural extent. While not a true systematic classification of agroecosystems, it identifies areas which are likely to share common features and to face similar environmental constraints and opportunities. Sixteen agroecosystem groupings are included with the majority of agricultural land found in temperate and warm tropic/subtropical areas. Arid and semi-arid lands comprise approximately one third of the total agricultural extent. Although dry sub-humid zones are not mapped separately here, if they were included with the arid and semi-arid lands, drylands would comprise over one third of the global lands used for agriculture.
When drylands are isolated from the global extent of agroecosystems, non-agricultural drylands are more easily spotted (Map 15). These non-agricultural drylands generally coincide with the arid zone; semi-arid and dry sub-humid zones are more typically cropland. The non-agricultural drylands also tend to coincide with the livestock only, rangeland-based livestock production system as shown in Map 6 (See, “Livestock”).
In this analysis, we have examined various statistics on food production in countries with extensive dryland (at least 90 percent of total land area). Of these 17 countries, total cropland varies from as few as 7,000 hectares in Kuwait to over 30 million hectares in Kazakhstan. Noteworthy, is that average cereal crop yields, for the period 1999-2001, when compared to the respective regional averages, are all below average (with one exception: Gambia) with large declines in some countries of over 50 percent. The lowest average cereal crop yields for this period were in Sub-Saharan Africa, in Botswana and Namibia, with less than 350 kilograms per hectare.
Equally noteworthy, are the data on variation in domestic cereal production (or the average percent variation from the mean in cereal production). As expected for countries in regions characterized by variability in rainfall, the variation in domestic cereal production is greater for these countries with extensive dryland than the regional averages. The variation in domestic cereal production, between 1992 and 2001, is 20 percent or higher in 9 countries where regional average variation from the mean range from approximately 4 percent in Asia to 7 percent in Sub-Saharan Africa. When variation in cereal production is high, it can indicate unstable food production and thus an unpredictable food supply, especially when most of the cereal crop is consumed locally as a primary dietary mainstay.
Two additional country-level statistics suggest a more complex pattern for food production in drylands. In many of these dryland countries (10 of 17), in the year 2000, net trade of cereals as a percent of consumption (including food aid), were at or above their respective regional averages. In addition, as a potential indicator of whether a country has achieved sufficient food security to keep its population healthy, the values for average daily per capita calorie supply show that more than half of the countries are above average. Thus, below average cereal crop yields and high variability in cereal production characterize these dryland countries, but there are exceptions and some countries appear to be able to produce sufficient food to support local populations.
Another measure of potential food production in drylands is the amount of land under irrigation. When compared to their respective regional averages, for the year 1999, half of the 17 dryland countries were below average in irrigated land as a percent of cropland. Sub-Saharan Africa had a very low regional average, but the five dryland countries within this regional all still fall below this low average. Additional countries with very low irrigated land in relation to total cropland include Kazakhstan and Tunisia.
Sources
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