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Approximately 45% of the world's total land area is considered drylands. The extent of drylands in various regions ranges from a low of 20% in North Africa and the Near East to 95% in North Asia, east of the Urals (Table 14.1). An estimated 38% of the world's 6 billion people live in dryland areas. Perhaps more important is that many of the people living in dryland areas are actively involved in agriculture. For example, of the 3.36 billion people living in the Asia and Pacific region, almost 60% are engaged in agriculture, many of whom are in dryland areas. This compares to only 3% of the people in North America who are engaged in agriculture and 13.5% in Europe (Table 14.1). Consequently, dryland areas are of great socioeconomic importance, and are likely to become more so in the future. The areas included in Table 14.1 cover a wide range of water conditions, although water is limited in all these areas for portions of the year. As population pressure increases, the net result is that more people move into less-favored areas. In essence, people move to the droughts instead of the droughts moving to the people. Hazell (1998) stated that despite some out-migration, population size continues to grow in many less-favored areas, but crop yields grow little or not at all. Hazell (1998) reported that about 500 million people live in less-favored areas, mostly in Asia and Sub-Saharan Africa; and if current trends persist, by 2020 more than 800 million people will live in less-favored lands. Hazell stressed that it is becoming increasingly clear that, on poverty and environmental grounds alone, more attention must be given to less-favored lands in setting priorities for policy and public investment. The rapid population growth in arid and semi-arid regions has placed tremendous pressure on the natural resource base. Often, the inevitable result of increasing population in resource-poor areas is land degradation. Droughts, which are common to these areas, exacerbate degradation processes. Land use practices in drylands are often opportunistic. Dryland farmers tend to maximize take-off during good periods and minimize loss during dry periods.

Cereals directly supplied around 57% of calories in the global human diet in 2000 (Food and Agriculture Organization [FAO], 2000b). The meat and dairy foods produced from animals that consumed 33% of world cereals provide additional calories. Together, wheat (Triticum aestivum), rice (Oryza

Table 14.1 Land Area by Dryland Type, Total Population, Population in Drylands, and Agricultural Population, in World Regions

World Land Area

Dry

Total World

Population

Agricultural

(% of 134

Arid

Semi-arid

Subhumid

Population

in Drylands

Population

Regions

million km2)

(%)

(%)

(%)

(% of 6 billion)

(%)

(%)

Asia and Pacific

21.5

6

15

17

56

44

59.5

Europe

5.4

<0.5

13

16

12

18

13.5

North Africa and Near East

9.5

4

11

5

5

44

44.3

North America

14.8

12

28

23

5

19

3.0

North Asia, east of Urals

15.6

11

51

33

4

89

17.4

South and Central America

15.4

11

6

10

8

24

23.0

Sub-Saharan Africa

17.7

6

13

19

10

36

65.0

World (Total)

100

7

20

18

100

38

45.8

Note: Lands classified as hyperarid make up an additional 19% of world land area, but are not included as dryland areas because the Food and Agriculture Organization assumes that these lands are too dry to sustain agriculture.

Source: Adapted from Food and Agriculture Organization. 2000a. Land Resource Potential and Constraints at Regional and Country Levels. World Soil Resources Report 90. Food and Agriculture Organization, Rome.

Note: Lands classified as hyperarid make up an additional 19% of world land area, but are not included as dryland areas because the Food and Agriculture Organization assumes that these lands are too dry to sustain agriculture.

Source: Adapted from Food and Agriculture Organization. 2000a. Land Resource Potential and Constraints at Regional and Country Levels. World Soil Resources Report 90. Food and Agriculture Organization, Rome.

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On sativa), and maize (Zea mays) make up approximately 85% of the world's cereal production. Wheat and rice are by far the most widely consumed cereals in the world, while maize is important for both direct and indirect human consumption. Approximately 67% of maize production is used as animal fodder. The FAO (1996) reported that 48% of cereal production in developing countries (excluding China) came from irrigated lands. This is in contrast to many developed countries where cereals, particularly wheat and maize, are largely grown without irrigation. It is estimated that 60% of wheat produced in developing countries is irrigated, while only 7% of wheat and 15% of maize are irrigated in the United States (U.S. Department of Agriculture, 1997). Other major cereal-producing areas such as Canada, Australia, and Europe are mainly nonirrigated.

World food production over the past four decades has more than kept pace with the rapid growth in population. Between 1961 and 1997, world population increased by 89% and food production per person increased by 24%, while food prices fell by 40% in real terms (Wood et al., 2000). This is a remarkable achievement on a worldwide basis, but global statistics do not reflect the wide range of differences between and within individual countries. The agronomic technologies that allowed the increases in world food production were largely based on high-yielding varieties, fertilizers, pest control, and irrigation. Irrigation has been particularly important in developing countries where the total irrigated area increased from 102 million hectares in 1961 to 207 million in 1999. This compares to 37 million hectares in the developed countries in 1961, and 67 million in 1999 (FAO, 2000b). Worldwide, about 17% of cropland is irrigated, and accounts for 40% of food and fiber production (Wood et al., 2000). On average, irrigation claims nearly 70% of world water abstraction and over 90% in agricultural economies in the arid and semi-arid tropics, but less than 40% in industrial economies in the humid temperate regions (FAO, 1996). With the cost of developing additional irrigated lands ranging from US$2,000 to US$10,000 per hectare (FAO, 1995, 1997a, 1997b, 1999), it is imperative that alternative water management and production system be considered for at least a part of the anticipated food demand.

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