バングラデシュ・ハオール農村の水文環境と稲基幹作付様式の展開(<特集>バングラデシュの農業と農村)

Abstract

Research on rice-based cropping patterns was carried out from 1986 to 1989 in Jawar village, which is located on the fringe of a haor in Kishoreganj District, Bangladesh. Thirteen major cropping patterns, of which nine are rice-based, were found to exist in the village. Aus-and Aman-rice-based cropping patterns were distributed in the kandhilla jami (high lands) and Boro-rice-based ones were predominant over shail jami or boro jami (low lands). The distribution of existing cropping patterns was found to be closely related to toposequences and consequently to the water regime in the village. Evolution of rice-based cropping patterns in the village has been characterized by a continuous trend of decline of broadcast-Aman rice (B. Aman) and expansion of Boro rice. The outbreak of water hyacinth since the big floods of 1920 and 1921 discouraged B. Aman cultivation, but it encouraged Boro rice cultivation. The introduction of don, traditional irrigation devices, and the construction of janghal, embankments to store the flood water until the dry season, accelerated the expansion of Boro rice cultivation in the 1920s and 1930s. The expansion was further accelerated from the 1930s with the preparation of khilla lands, which were reclaimed by digging and lowering land surfaces to make them suitable for Boro rice cultivation. The introduction of modern irrigation devices like low-lift pumps and shallow tubewells has also accelerated the Boro-rice expansion since the late 1960s. Such stepwise expansion through the introduction of both traditional and modern technologies reveals that the existing cropping patterns are a result of villagers' adaptation to a specific hydrologic environment, in this case a haor, in the low-lying areas in Bangladesh.