Journal of Taiwan Agricultural Research

Table 8.　The simulation of rice income and expected loss in townships in Chiayi County.

Author:Dah-Jing Liao*

Abstract:

The main objective of this study is to analyze the dependency between yield and price variables of rice cultivation in the main townships of Chiayi County through Copula functions, in order to estimate income risks and provide references for rice production adaptation measures. The analysis results indicate that, except for the first cropping season in Yizhu Township and the second cropping season in Zhongpu Township and Liujiao Township, the Kendall's tau correlation coefficients between rice yield and price in other townships during both cropping seasons show a negative correlation. However, the correlation coefficients are relatively low, indicating weak correlation. In terms of tail dependence, the first cropping season in Yizhu Township shows upper tail dependence, while the second cropping season in Zhongpu, Minxiong, and Xingang Townships exhibit symmetric tail dependence, and Liujiao Township shows upper tail dependence. The other townships display no significant tail dependence or lower tail dependence in both cropping seasons. Notably, for the first cropping season, most townships exhibit yield and price coupling fitted with the Clayton Copula function, which is sensitive to lower tail dependence. Due to the frequent impact of extreme weather during the late growth stage of the first cropping season in recent years, the potential risk of lower tail dependence, where both low yield and low price occur simultaneously, cannot be ignored. Lastly, simulated expected losses in rice income for each township were calculated to assess income risk. The findings reveal that, except for Minxiong Township, the expected losses during the second cropping season are higher than those in the first cropping season. This is possibly related to meteorological disasters during the early growth stage of the second cropping season and lower solar radiation in the later stages, which increases production risks. When comparing the expected losses across townships, Liujiao and Yizhu Townships show higher losses in both cropping seasons, likely due to the harsher rice cultivation environment in coastal areas, leading to greater income volatility. Future efforts may focus on developing adaptive cultivation technologies or breeding new stress-resistant varieties to enhance the resilience of rice production in coastal areas and reduce income risks.

Key words:Rice, Copula function, Dependence