Cyclicity of favorable and unfavorable years for winter wheat in Ukraine

Abstract

Purpose is to study the impact of 4-year cycles of leap years on the productivity and gross harvest of winter wheat in Ukraine, in the context of the possibility of forecasting crop and yield years. Methods: field, statistical, analytical, computational and theoretical generalization. Results. Studies have shown that in the leap years the production of wheat grain in Ukraine is significantly reduced, and higher grain harvest and yield of winter wheat provides in the first year after the leap year. Thus, on average in 1960–2021, the grain harvest in Ukraine amounted to 19.0 million tons, in the leap years 16.82 million tons, and in the year after the leap year it reached 21.61 million tons, which is 5.03 million tons, or 30.3% more than in leap years and 2.52 million tons or 13.2% more than the average for the years of research harvesting its grain. The decrease in grain production in the leap years is mainly due to the fact that the autumn before the leap years was usually dry, so in autumn weak and liquefied crops were formed, much of which was replanted in the spring, which led to grain shortages. In addition, the yield in the leap years was lower than the average for the research years. The higher grain harvest in the years after the high season is due to more favorable weather conditions in the autumn growing season and more rainfall during the entire growing season, which provided a higher grain yield than in the high years. The identified pattern makes it possible to predict favorable and unfavorable for the formation of the wheat harvest in winter and to develop economic and technological solutions aimed at maximizing the productivity potential of agrocenoses in these years. The probability of forecasting lean and productive years in this way is 81%. Conclusions. A 4-year cycle of favorable and unfavorable years for growing winter wheat in Ukraine has been identified. In leap years, the production of winter wheat grain decreases compared to the average harvest, which is due to the dry autumn and less than normal rainfall in the spring and summer of its growing season. High yield and grain harvest of winter wheat provides in the next year after leap year, due to favorable conditions of autumn leap year for crop development, more rainfall during the growing season and lower air temperatures in spring and summer. The identified pattern makes it possible to predict favorable and unfavorable years for the formation of winter wheat harvest and to develop economic and technological solutions aimed at maximizing the productivity potential of agrocenoses in these years. The probability of predicting favorable and unfavorable years for wheat, according to 4-year cycles of leap years, is 81%.