Drought Impact on Variability Crop Yields in Central Bohemia

This paper presents the results of a study on the estimation of drought impact on fluctuation yield cereal crops in Central Bohemia. Historical climate and crop yields data for the period of 47 years (1961-2007) have been integrated into an agrometeorological database. The objective of this paper was to determine the drought impact on yield of winter and spring cereals crops on an example for the Central Bohemian region. According to crops variability models the most of low yielding years (from 3 to 5 cases) were noticed at the beginning of the 1960s and 1970s, reaching their highest points in the decade of 1991-2000 (from 3 and 8 cases). In the case of the most serious crop failures in grain production in the Central Bohemian region (1964, 1976, 2000, 2003), droughts were responsible. In agreement with the developed model, the drought impact was associated with cereals detrended yield being smaller than y(i)((T)) <= -0.5 sigma. A year has the following types of drought impact: yield detrended of -0.5 sigma >= y(i)((T)) > -sigma is a low drought effect; -sigma >= y(i)((T)) > -1.5 sigma is a middle drought effect and y(i)((T)) <= -1.5 sigma means a high drought effect.