Spatial and temporal yield dynamics of corn for grain within the Volyn region
Aim. To establish the spatial and temporal variability in yield of corn for grain in the Volyn region in 1965-2017. Methods. Agricultural research, multivariate statistics, cluster analysis, geographic information technology. Results. From 1965 to 2015, the highest yield of corn for grain in the Volyn region was observed in the southern regions, and the lowest yield level was established for the northern regions. According to the peculiarities of the temporal dynamics of corn yields, the administrative regions are classified as allocating spatially homogeneous complexes consistent with the Forest-steppe, Polissia, and the Transitional Zone. The indicators of the dynamics of corn yields in all regions are characterized by a positive asymmetry coefficient, indicating an asymmetric distribution with a shift to the left. The presence of asymmetry indicates the heterogeneity of conditions and the cultivation of corn for grain during the study period and the possibility of identifying qualitatively homogeneous time intervals, that is, for the periodization of the investigated hour interval following the yield indicators of corn for grain. The geography of homogeneous clusters identified based on indicators of the dynamics of grain corn, which to a certain extent corresponds to the physical and geographical zoning of the region, is evidence of the ecological conditionality of corn yield by modes that correlate with factors of physical and geographic heterogeneity of the region. Of the ecological and geographic factors, climatic conditions were the most variable over the corresponding period. From 1965 to 2015, the nature of the dynamics of grain corn yields underwent qualitative transformations, which are the basis for appropriate periodization. Essential markers of the respective periods are the general yield level and the yield trend's general direction. Conclusions. The highest yield of corn for grain in the Volyn region was observed for the administrative districts located in the forest-steppe zone, and the lowest was characteristic for the districts within Polissia. The level of grain corn yields in the region may differ by almost 2.9 times, resulting from the soil's heterogeneity and climatic conditions. The dynamics of the production process in the forest-steppe zone and Polissia are in antiphase: favorable conditions for increasing yields in one geographic zone are accompanied by opposite conditions for the adjacent zone and vice versa. Grain corn yield in 1965–2015 showed cyclical dynamics, during which periods with two local maximums were observed: in the ninth decade of the 20th century and the second half of the first decade of the 21st century.