Tadeusz Gorski

Abstract

An important source of risk in agricultural production is the variability to crop yields refl ectingirregularly changing weather. This variability may be described as a stochastic process that has a functionof density. Analyses of historical data on crop yields reveal that the function of density changedfrom right-skewed to left-skewed, along with increasing mean yields. All examined yields of cropscultivated recently in Poland demonstrate the left skew, which does not diminish with the aggregationof acreage. A fairly good approximation of the probability distribution for actual yields may be obtainedusing the log-normal distribution with an inverted abscissa.

Keywords: crop yields, density function, log-normal distribution, area aggregation, scaling of variance

Tadeusz Gorski, Department of Agrometeorology and Applied Informatics, Institute of Soil Science and Plant Cultivation – State Research Institute Czartoryskich 8, 24-100 Puławy, Poland