Long-term Change and Short-term Fluctuation of Production of Wetland Paddy in Java, Indonesia - Precipitation Change and Farmer's Response -

We examined the wetland paddy production and its change in Java and Bali based on the statistics prepared by BPS-Statistics Indonesia (Badan Pusat Statistik) from 1976 to 2000 in units of province (propinsi) and district (kabupaten). The short-term fluctuation and the long-term change were separated from the yearly data of rice production. As for the long-term change, the yield rates increased in about first ten years of the period by injecting the chemical fertilizers and introducing new varieties, the harvested areas also increased by the development of irrigation systems and so on, and the production grew remarkably. On the other hand, the growth rate of those indices decreased in the latter half of the period, and short-term fluctuation responding with ENSO cycle came to be recognized clearly. Though the influence of small precipitation caused by the El Nino hardly appears in the yield rate, the fall of the harvested area is remarkable, which causes a decrease in production. The influence is obvious in the area with an annual precipitation of around 2,000 mm and clear in the years with small rainfall in the early rainy season, especially until November or December. The areas affected most severely by the fluctuation of precipitation are neither the areas with small precipitation with irrigation facilities, nor the area of a large precipitation of over 3,000 mm. It is suggested that the influence of drought is represented by giving up growing rice at the field of poor condition or by reducing the time of cropping. Field investigation was carried out on a farm village in West Java located on the north foot of Volcano Salak, to figure out the manner of the farmers' response to small rainfall. The survey confirmed the above hypothesis. Some farmers have experienced substituting some upland crops for wetland paddy due to small rainfall. On the other hand, the farmers who have large rice fields do not have even that experience. The fact suggests that the upper farmers are less affected by drought ; in other words, the sensitivity to environmental fluctuation is different by social classes. * Institute of Geography , Graduate School of Science, Tohoku University ** Graduate Student of Institute of Geography , Graduate School of Science, Tohoku University *** Department of Environmental Systems , Faculty of Geo-Environmental Science, Rissho University Science Reports of Tohoku University, 7th Series (Geography) Vol. 52 Nos. 1/2 March, 2003 2 Yoshiyuki MURAYAMA, Kiyotaka SAKAIDA, Nao ENDO and Toshikazu TAMURA