• Rice is eaten by about 3 billion people and is the most common staple
    food of the largest number of people on earth (Maclean et al., 2002). In the
    1960s, the combination of new high‐yielding varieties with increased input
    use, such as water, fertilizer, and biocides (agrochemicals to protect the crop
    from pests, diseases, and weeds), initiated a rapid increase in productivity
    that is called the Green Revolution (Khush, 1995). Because of this increased
    productivity, and an increase in cropped area, total rice production in the
    first two decades of the Green Revolution more than kept pace with the
    tremendous growth in population in Asia (Fig. 1). The increased productivity
    and profitability also contributed to food security and poverty reduction
    among farmerswith irrigated land (Dawe, 2000). The growth in rice production
    outstripped growth in population, thus lowering prices,which reduced the daily expenses for food of poor consumers such as the rural landless, urban laborers,
    fishers, and farmers of nonrice crops. World rice prices (adjusted for inflation)
    fluctuated around US$1000 per tonne between 1961 and 1981, saw a sharp
    decline between 1981 and 1984, and then a gradual decline until a record low
    aroundUS$250 per tonne in 2002 (Fig. 1). The world rice price is now just 25%
    of its level in the early 1980s and national prices show a similar trend. However,
    whereas the low price of rice has benefited rice consumers, it now threatens the
    livelihoods of rice farmers, the very segment of the population that helped to
    alleviate poverty in the first place.
    Because rice is mostly grown under flooded, or submerged, conditions, it is
    also one of the biggest users of the world’s developed freshwater resources
    (Tuong and Bouman, 2003). However, water is becoming increasingly scarce
    and grave concerns exist about the sustainability of irrigated agriculture
    (Rijsberman, 2006). The Comprehensive Assessment of Water Management
    in Agriculture (www.iwmi.cgiar.org/assessment) seeks answers to the question
    of how water can be developed and managed to feed the world’s population
    and reduce poverty, while at the same time promoting environmental
    security. To answer this question, it synthesizes existing knowledge and
    stimulates thought on ways to manage water resources to continue meeting
    the needs of both humans and ecosystems in the future. The results will enable
    better investment and management decisions in water and agriculture in the
    near future. Because of the importance of rice and the large amount of water
    used to grow it, the Comprehensive Assessment pays particular attention to the relationship between rice and water, between the rice–water interface and
    food security and poverty alleviation, and between rice ecosystems and the
    environment. This chapter presents the scientific analysis underpinning that
    assessment. In the first part, past and current trends and conditions are
    synthesized and the major challenges in the 25 years ahead are identified.
    The second part reviews response options to these challenges, at the levels of
    plant, field, and irrigation system. The analysis focuses on Asia, where some
    90% of the world’s rice is produced and consumed (Maclean et al., 2002),
    complemented by information from other regions where this adds to our
    understanding of the relationships between rice and water.

  • B. A. M. Bouman, E. Humphreys, T. P. Tuong and R. Barker

  • Journal Article

  • Advances in Agronomy

  • 92

  • 187-237

  • 2006-00-00

  • 0065-2113

  • 10.1016/S0065-2113(04)92004-4

  • View

  • East Asia; South Asia; Southeast Asia