Contents & Foreword, Characterizing And ... - IRRI books

first working group to identify the macro soil/climate zones of rice production inSoutheast Asia (IRRI 1974). A comprehensive agroclimatic classification for evaluatingcropping systems in Southeast Asia based on the amount of monthly rainfall andlength of consecutive wet months was reported by Oldeman in 1974. A wet month isdefined as a month with at least 200 mm rainfall. The agroclimatic environments ofSoutheast Asia were classified into four zones (Oldeman 1974):● Zone I: more than 9 consecutive wet months● Zone II: 5–9 consecutive wet months; zone II has four subzones● Zone III: 2–5 consecutive wet months; zone III has three subzones● Zone IV: less than 2 consecutive wet monthsSince then, several attempts to characterize and classify rice production environmentshave been carried out by different scientists working in different locationsaround the world. The bases for characterizing rice production environments used upto the mid-1980s, however, are different (Table 2). Recognizing the importance ofhaving a common agreement on environmental terminology so that plant type can bebetter related to environments, IRRI established in 1982 an international committeeto develop an agreed-upon terminology and classification for rice (IRRI 1984).The recent characterization and classification of the environments of rice productionin inland valleys in West Africa. Rice is an important food crop in West Africa,but local production has not been able to meet popular demand, resulting in thespending of large amounts of foreign exchange by governments in the region to importrice. The region has large wetland areas in inland valleys, however, that are stillnot fully exploited. Considerable efforts have therefore been made recently to characterizeand classify the environments in these inland valleys, where rice has been atraditional crop. The efforts have been carried out since 1982 by various national andinternational institutions, such as the International Institute of Tropical Agriculture(IITA) (Windmeijer and Andriesse 1993), Conférence des Responsables de RechercheAgricole Africains (CORAF) (Albergel et al 1993), the Centre de CoopérationInternationale en Recherche Agronomique pour le Développement (CIRAD) (Legoupiland Bidon 1995), and the West Africa Rice Development Association (Becker andTable 2. The classification of rice production environmentsduring the 1970s to early 1980s.Basis of classification/characterizationExercises (no.)General surface hydrology 15Physiographic source of water 3Landform and soil units 3Matrix of ecological factors 9Soil suitability 3Crop season, intensity, and management 3Comprehensive (combination of above 6 items) 2Total 38Source: Bowles and Garrity (1988).36 Van Nguu Nguyen