Geographical Review of Japan Vol. 66 (Ser. B), No. 1, 70-88,1993 Climatic Change and Rice Yield and Production in Japan during the Last 100 Years Masatoshi YOSHINO* Abstract First, general trends of rice yield and production and changes of air temperature , precipita tion and sunshine hours in Japan during the last 100 years are described. In yield , three periods can generally be recognized: Period 1, from the end of the 19th century to about 1915 , Period 2, from about 1915 to about 1945, the end or just few years after the 2nd World War , and Period 3, after the end of the 2nd World War. Secondly, fluctuation of climatic conditions and its effects on the paddy rice yield during the last 104 years were studied statistically in order to evaluate the different impacts according to period . By applying the principal component analysis method, their distributions, periodicities and relations to monthly mean air tempera ture, monthly total precipitation, and monthly total sunshine hours were studied . The first component has a significant correlation to all three climatic elements in July , and air tempera ture and sunshine hours in August and precipitation and sunshine hours in September . In the second part of this study, we classify the 104 years into three periods according to interannual changes of paddy rice yield. For these three periods , the general trends and fluctuations are described and the relationship between the yield and climatic elements are analyzed for five regions respectively. Key words: Climate change, Climate fluctuation, Climatic impact , Agroclimate, Paddy rice yield. tamed much data related to the present theme . I. INTRODUCTION Along with an international project on an as sessment of climatic impact on agricultural pro Climate changes and fluctuates over various duction in the case of global warming in the 21 time scales. In order to analyze the relationship st century, Japanese cases have been studied between climatic change/fluctuation and agri (YOSHINOet al., 1987). On the other hand, gener cultural yield/production during the last 100 al trends and fluctuations of the rice yield in years, the present paper first describes the gen Japan in the last 100 years have been analyzed eral trend of Japanese agriculture and second by UCHIJIMA,Z. (1981). the climatic conditions, particularly change/ Besides those written in English, numerous fluctuation, cycles, and abnormal weather oc comprehensive studies have been published in currences in Japan. In the next part of the Japanese. Due to considerations of space, the study, the impact of such climatic conditions on history of research on the present theme has paddy rice production are dealt with. not been discussed here, but its beginnings Just 20 years ago, research status and prob were as early as the last decades of the 19th lems in agricultural climatology (YosHINo, century. In the 1930's and 1940's, there already 1974), crop-weather relationship (HANYU, 1974) existed many books and monographs as well as and meteorological hazards (UEMURA et al., articles on this subject. Among others, the most 1974) in Japan were summarized. An interna comprehensive studies were made by DAIGO tional symposium on "Climatic change and food (1943, 1944, 1945). production" was held in Tsukuba in 1977 and Based on the review of previous studies, we its proceedings (TAKAHASHIet al., 1978) con now turn to the analysis of regional differences * Aichi University , Toyohashi 441, Japan Climatic Change and Rice Yield in Japan 71 in tendencies for long year series. In order to paddy rice cultivation had already spread up to contribute to these problems, an attempt was the southwestern part of Hokkaido, north made to analyze them by division into three Japan, in the Yayoi period, 2,500 years B. P. stages of development of rice cultivation. However, the irrigation system including drain age and flood control ("Water-control stage") II. GENERAL TRENDS OF PADDY RICE had been established in about AD 645 as shown YIELD IN THE LAST 100 YEARS in Fig. 1 (TAKASEet al., 1969). From the end of the last century, Japanese agriculture entered Modern archeology has made it clear that the "Inputs stage", by actively introducing fer Fig. 1. Historical development of irrigation and rice production in Japan compared with other rice-cultivat ing countries (TAKASEand KANo,1969). Lines in the lowerpart show the year-by-yearchanges of paddy yield in Japan (LineA) and in other countries,Australia, china and Thailand. II, III and IV indicatethe "Water-controlstage", "Inputs stage", and "cultivation-methodstage" in the respectivecountries. The upper part of figure,Line B shows the changeof farm land in Japanand Line Cnumber of irrigationdams in Japan. 72 M. YOSHINO Fig. 2. Geographical distribution of rice yield by country in relation to latitude (TAKASEand KANO,1969). ADB:Asian DeveiopmentBank. tilizer, new varieties, pesticides etc., and from shown in Table 1 (YAMADAet al., 1969). The 1950, it entered the "Cultivation-method stage". total yield in this country was about one third Rice yield in Japan is among the highest in that of India. the world. In Fig. 2, rice yield is shown in ac The trends in rice and other field crops pro cordance with latitudes (TAKASE et al., 1969). duction during the last 100 years show contin Rice yield is scattered widely in relatively uous increase in general, but with drastic higher latitudes, 31•‹ or more, but the average change in sericulture and livestock production values are increasing strikingly from 11-20•‹ to as shown in Fig. 3 (HAYAMI,1975). The total 31•‹ or more. Among the highest group, Japan is production, output and gross value added in the third or fourth counted from Spain as the agriculture have also increased continuously as top. The paddy production of Japan ranked shown in Fig. 4 (HAYAMI,1975), even though second or third in Asia about 30 years ago as the effect of the 2nd World War is striking. Climatic Change and Rice Yield in Japan 73 Table 1. Paddy Production in Asiaa (YAMADAet al., 1969) a) All statistics were provided by the respective governments, except those marked with an asterisk, which were taken from FAO Document No. CCP: RI 67/7. Table 2 shows the distribution of farms by size of cultivated land area, from 1908 to 1990. As is clearly shown, small scale family farms are predominant, which is still true in the 1980's (KAT5UKI,1993). That is to say, the struc ture of rural organization has been fairly con sistent during the years of the statistics. HAYAMI (1975) mentioned that, because of the heavy burden of taxes and rent, coupled with a lag in productivity growth in agriculture rela tive to the nonfarm sector, the level of income and consumption of farm households lagged behind urban households. This situation might be reflected in the consistent technical improve ments in agriculture in Japan, but the farm sizes remained in a similar percentage distribu Fig. 3. Trends in agricultural production by com tion. Because the small size farms are generally modities. considered to be more sensitive, due to the Adjusted to 1934-1936constant pricesshown by 5-year economically weak background of farmers, to averages(HAYAMI,1975). such unfavorable conditions as anomalous weather, these farm size characteristics should wider year-to-year fluctuation over recent be taken into consideration. Increase of part years. This is because production has already time farmers during recent years should also be reached the higher stages and the area of fields considered quantitatively, but related problems and yield cannot be drastically increased. In need to be considered in further studies. contradistinction to this, the United States and YOKOYAMA(1990) described Japanese rice Australia put large machinery into rice cultiva production as similar to that of European coun tion and produced for export at lower cost, tries, with a slowly increasing tendency to particularly since the 1970's. For example, the 74 M. YOSHINO Fig. 4. Trends in total production, total output, and gross value added in agriculture. Adjusted to 1934-1936 constant prices shown by 5-year-averages (HAYAMI,1975). Table 2. Distribution of Farms by Size of Cultivated Land Area a) Percentage distribution is shown in parentheses. Source: Institute of Developing Economies, One Hundred Years of Agricultural Statistics in Japan (Tokyo, 1969), p. 116; and Ministry of Agriculture, Forestry and Fishery, Statistical Research Division: World census of Agriculture Report on Farmhouseholds and Population, and Agriculture census and Agricultural Investigation. Data from 1908 to 1970 is also available from YAMADAet al. (1969). percentage of total farmers in the U. S.A. accord ing to harvested area for below 40ha is 27.5%, III. CLIMATIC CHANGE, FLUCTUATION for 40-100ha 33.9%, for 100-200ha 24.2%, for AND ABNORMAL WEATHER DURING 200-400ha 10.9%, and above 400 ha 3.5%. THE LAST 100 YEARS These figures are quite different from the values shown in Table 2. It is particularly strik Annual mean air temperature increased 0.4 ing that farms smaller than 1ha are still domi 0.5•Ž/100 years as the average for the whole nant, 67-68%, in Japan (JINNOUCHI,1992). country as shown in Fig. 5. If we look at it regionally, the trends vary. The maximum Climatic Change and Rice Yield in Japan 75 Fig. 5. Year-by-year changes of air temperature, precipitation and sunshine hours in Japan 1900-1980, annual mean or total. (Data sources: Japan Met. Agency, 1984). around 1960 is striking in the respective parts Islands, however, show a remarkable increase of Japan, though the trends in the 1970's are not with certain periodicity of about 24-25 years. the same. Precipitation shows very complicated fluctu Precipitation shows more complicated fea ations.