Quantitative Risk Assessment of Crop-Yield Variability by Crop and Prefecture by Using Crop Statistics

• Published in: Agricultural Information Research Vol. 31; no. 4; pp. 120 - 130
• Main Author: Nagai, Takashi
• Format: Journal Article
• Language: Japanese
• Published: Japanese Society of Agricultural Informatics 01.01.2023
• Subjects: crop statistics; crop-yield variability risk; risk hedge; risk management
• ISSN: 0916-9482; 1881-5219
• DOI: 10.3173/air.31.120

One risk-management approach to annual crop yield variability is to diversify the risk by cultivating multiple crops or by cultivating in regions with various climatic conditions. However, to my knowledge, no comprehensive risk analysis for each crop and region of Japan has been published. Here, I analyzed long-term national statistical data on crop yield from the Ministry of Agriculture, Forestry, and Fisheries of Japan to quantify the risk of crop-yield variability by crop and by prefecture. The difference between normal and actual yields in each year (shown as a crop-yield index, with a normal year having a value of 100) was assumed to occur randomly under a certain probability distribution. The average and the magnitude of variation in the distribution (standard deviation) were used as risk indices. Patterns of crop-yield variability were organized in terms of the relationship with meteorological factors such as temperature, the horizontal distribution of crop-yield variability in each prefecture, the similarity to annual variation patterns of paddy rice yield, and the relationship between risk and return. Furthermore, the effect of risk diversification by cultivating multiple crops and by cultivating in prefectures with different patterns of annual crop yield variation was simulated. Successful cases of the positive effect of risk diversification were observed when the correlation coefficient between combined crops or between prefectures was low.