RYE PRICE VARIABILITY IN POLAND BETWEEN 2010 AND 2018

In the paper, the range of rye price variability was determined and a decomposition of a time series of prices was carried out, distinguishing seasonal, cyclical and irregular fluctuations. The rye market is a market of a product produced seasonally but with a storage period longer than one season, which influences seasonal changes of prices, on which economic changes overlap. The research material consists of prices of rye in monthly graduation for the years 2010-2018, from the Integrated System of Agricultural Market Information. In the analyzed period, the nominal price of rye more than doubled from 327 PLN/t in January 2010 to 719 PLN/t in December 2018. The coefficient of variability of rye prices ranged from 4.0% to 27.2%. The decomposition of the time series of prices indicates seasonal, cyclical and irregular fluctuations. The amplitude of seasonal fluctuations was 14% on average, the highest prices were in June (105%) and the lowest in August (91%). Cyclical changes averaged 71.2% per year, seasonal changes 17.9% and irregular changes 10.9% of overall rye price variation. The production of rye is steadily falling both in the world and Poland.