季節湿地における農地拡大とその背景--タンザニア・ボジ県の事例

Abstract

This paper describes rapid expansion of agricultural land into seasonal swamps in Tanzania. In the Mbozi district of Mbeya, seasonal swamps have been mainly used for cattle grazing and for farming by indigenous cultivation methods. The recent expansion of agricultural land into the swamps, however, has narrowed the area available for grazing. The Mbozi district is one of the most significant coffee-producing areas in Tanzania. Since the liberalization of the economy, many coffee farmers have become eager to expand their farms in order to earn more money. As many farmers have switched from growing maize to coffee, the areas available for food crop cultivation have been reduced. Even farmers with sufficient land, as well as those without, began cultivating maize in seasonal swamps that had not been previously used for cultivation. In the face of such agricultural expansion, a new system of swamp use, partly based on indigenous agricultural systems, was created to enable maize to be cultivated in the middle of swamp areas. Although farmers have long been dependent on oxdrawn plows for cultivation, the decrease in cattle-grazing land has caused few problems, because the number of cattle has also decreased. The cattle necessary for plowing are now being recruited from adjacent mountainous areas, where the cultivated fields are located on slopes so steep that farmers do not depend on ox-drawn plows.