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Rice is the most important cereal crop in Tropical Asia. The importance of
rice relative to other crops, as well as to meat and milk, is indicated by recent
production figures (see Table 11-7). In Bangladesh,
Cambodia, Laos, Malaysia, Myanmar, Sri Lanka, and Viet Nam, rice constitutes
94-98% of total cereal production. Cereal production in Thailand and Indonesia
consists of 80% and 84% rice, respectively, with the remainder predominantly
maize. Rice production in India, Nepal, and the Philippines accounts for 50%,
52%, and 66% of the cereal produced; most of the remainder in India and Nepal
is wheat, and maize is another important cereal in the Philippines. With regard
to calorie intake in the monsoon region, 29-80% of the supply is contributed
by rice; calorie intake from rice is highest in Bangladesh and lowest in Malaysia
(Hossain and Fischer, 1995).
Anglo et al. (1996) note that changes in average climate conditions and climate variability will have a significant effect on agriculture in many parts of the region. Particularly vulnerable are low-income populations that depend on isolated agricultural systems. These communities include many areas that concentrate on the production of tropical crops, such as tea and coconuts, as well as regions with limited access to agricultural markets. Changes in climate variability would affect the reliability of agriculture and livestock production in the region. Increasing population also could place stress on agricultural production. During the past three decades, food production-largely rice and wheat-increased at a higher rate than did population growth, but these crops currently show signs of stagnating productivity; there also appears to be a decrease in the production of coarse grains in the region (Sinha, 1997).
Moreover, agricultural areas in Tropical Asia are vulnerable to many environmental hazards-including frequent floods, droughts, cyclones, and storm surges-that can damage life and property and severely reduce agricultural production. For example, on average during 1962-1988, Bangladesh annually lost about half of a million tons of rice-nearly 30% of the country's average annual food grain imports (BBS, 1989; Paul and Rashid, 1993)-as a result of floods. In India, the crop area affected by floods is nearly one-third of the average flood-prone area (GOI, 1992). More insidious changes in the groundwater level, as well as groundwater pollution, appear to be taking place in some high-productivity agricultural areas of the country (Sinha, 1997).
Two additional factors increase the vulnerability of the agricultural sector in the region. First, even though 35% of the region's land is irrigated (Annex D), a significant portion of agriculture is rain-fed. About 46 million ha, or 88.5%, of global rain-fed lowland rice is cultivated in south and southeast Asia (IRRI, 1993). In eastern India, approximately 80% of the 20 million ha of rice is grown in rain-fed lowlands (Zeigler and Puckridge, 1995). Yields for rice under rain-fed conditions in Asian tropical regions are low, compared with those of irrigated rice yields. A number of factors explain this pattern, including floods, droughts, temporary inundation from rainfalls, and tidal flows and coastal salinity (Hossain and Fischer, 1995).
Second, the region supports a large human population per hectare of cropland: 5.4 people per hectare in south Asia and 5.7 in southeast Asia. Although the rate of growth of rice yields is modest in many countries of the monsoon region, it has been estimated that per-hectare rice yields will need to be doubled by 2025 to meet demand. Even if yields in rain-fed lowlands can be doubled through the development of high-yielding varieties that are resistant to floods, droughts, and problem soils, the required rice yield from irrigated areas by 2025 will be about 8 tons/ha (compared with current yields of 4.9 tons/ha) (Hossain and Fischer, 1995).
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