In this study we analysed harvest of the two broad groups of grain crops, namely winter and spring cereals. The aim of the research was to develop and apply an index decomposition analysis model for assessment of changes in crop harvest. Consequently, we defined four factors quantifying effects of amount of cropped area, crop spatial distribution inter counties, species mix within counties, and yield. This study focuses on changes in harvest of grain crops, namely winter and spring cereals, in Lithuania. These two broad categories were analysed at the county level throughout the period of 2000–2010. The area effect was the driving force causing increase in cereal harvest. The structure effect (re-location of crop areas among different counties of Lithuania) resulted in increase in total cereal harvest. The alteration of proportions of the area under different cereal species in certain county lead to positive species mix effect. Hence, these decisions can be considered as rational ones. Nevertheless, unfavourable climatic conditions lead to decrease in yields, i. e. negative yield effect was observed. Further modifications of the proposed model, hence, might be useful tools for decision aiding
