Yield Stability in Crop Production

Hollósy, Zsolt – Bacsi, Zsuzsanna

Keywords: crop yield, fluctuation, risk, time series, yield stability, technology level, C43, Q54, Q55, Q58

The technology of crop production should provide high yields under varying environmental conditions typical for the geographical zone of production. However, crop yields may fluctuate from year to year. As long as these fluctuations are small, the technology reliably delivers yields close to expectations, but occasional extreme low or high yields can cause serious concern for farmers. Thus the fluctuations of yields should be kept within reasonable limits. The level of fluctuation is usually measured by statistical dispersion indicators, e.g. standard deviation, or coefficient of variation. These indicators, however, give an average measure of fluctuations, and the same dispersion value can occur as the result of many small deviations, or of a few large ones. Farmers may well tolerate small yield fluctuations, as acceptable uncertainties of crop production, but a few extremely low or high yields may be disastrous for them. The present paper introduces an adjusted measure of a yield stability index and tests it for 10 countries and 18 crops. Results are compared for two time periods, 1961-2000 and 2004-2016, to show, which crops are produced with the most reliable technologies in various countries. For each country the group of well technologized crops are defined, for which the applied technology is capable of maintaining a stable average yield for many decades regardless of the changes of the external environment. In Hungary more than 70 % of the analysed crops are weakly technologised, including wheat, barley and maize, while only five crops – sunflower, green peas, cucumber, cabbage and spinach – are well technologised. This is the worst result among the 10 countries assessed in the paper.

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