WINTER WHEAT PRODUCTIVITY ON DRAINED SOD-PODZOLIC SOILS OF VOLYNS POLISSYA DEPENDING ON APPLYING FERTILIZER SYSTEMS AND TEMPERATURE CONDITIONS

Relevance of the research. Winter wheat is considered to be a leading cereal crop. One of the area of stabilizing this crop production is to intensify its cultivation on the drained soils of Polissya. Due to the changes in external factors (global and regional climate change, soils, etc.) and technology, the question of modeling the process of crop productivity formation remains relevant. Objective of the research was to evaluate the impact of climate change (increase of average air temperature) on the winter wheat yield on the drained lands of Western Polissya when applying different fertilizer systems. Research methodology. The research was conducted in a stationary long-term field experiment of the Volyn State Agricultural Research Station of NAAS. The following fertilizer systems were investigated: control (without fertilizers); organic fertilizer – green manure crop; mineral fertilizer - N60P60K60 + lime; organic-mineral fertilizer - N60P60K60 + green manure crop + lime. In the course of the study, a systematic analysis of long-term results of field experiments and meteorological observations using mathematical and statistical methods, correlation and regression analysis were used. Research results. The coefficient of yield variation over the years of research on a variant without fertilizers reached 27%, against 19% for the organic-mineral fertilizer system. Applying the fertilizers helped to reduce the variability of winter wheat yield by 19 - 23%. Correlation analysis of winter wheat yields in view of the average air temperature of the early spring period (from the second decade of February to the first decade of April) was 0.85. Low air temperatures in this period indicate the late dates of the beginning of spring crop vegetation, which negatively affected wheat productivity. Relatively high temperatures contribute to earlier spring processes and, accordingly, positively affected the yield formation. The correlation coefficient of the average air temperature and wheat yield in the spring-summer period (second decade of April - the second decade of July) was - 0.71. Conclusions. The highest efficiency on sod-podzoliс drained soils is provided by applying organic-mineral fertilizer system. The average wheat grain yield when applying this fertilizer system was 5,7 ton per hectare (+ 38% over control). The application of balanced fertilizer systems reduces the amplitude of grain yield fluctuations from 27% to 19%. The temperature regime in the period from the 2nd decade of February – till the 1t decade of April has a significant effect on the yield of winter wheat grains. Having the average temperatures over 5оC, yields increased by 1-1,5 ton per hectare, and on the contrary, rise of average temperatures in the spring-summer period more than 16оC significantly reduced this index. The established mathematical dependences enabled to estimate the projected winter wheat yield by the analysis of the temperature regime over the years. The conducted research and established features make it possible to calculate the projected winter wheat yields by the temperature regime of the period from the end of February till the beginning of April. The study of the interrelation between the crop productivity and the combined action of temperature and water regime is supposed to be the next stage of the research.