Effect of Changes in the Agro-Climatic Resources of the Steppe Volga Region on the Effectiveness of Long-Term Use of Mineral Fertilizers in Millet Crops

The results of a study of changes in the agro-climatic resources of the steppe Volga region during millet cultivation in a long-term stationary experiment with mineral fertilizers (1996–2022) are presented. An increase in the amount of active temperatures for the year and the period May–August, as well as its negative impact on millet yields in the experiment, is established. A decrease in the yield of millet grain in fertilized varieties was noted with a decrease in the value of the hydrothermal coefficient for May–August. The most significant climatic factor affecting the yield potential of millet in the experiment was the average monthly air temperature in July. Its marked growth in the last 3 crop rotations contributed more to a decrease in crop yield, especially in fertilized variants (r = −0.69 in the control and r = −0.79 in fertilized variants on average). The average monthly air temperatures in May, June and August had no effect on millet productivity.