Analysis of winter rye production trends and yield dependence on forecrops and sowing rates
Authors: Borovyk S. O. , Budionnyi V. Y. 
Published: August 2023

The purpose and objectives of the study. The study purpose was to investigate trends in the winter rye production volumes and factors on farms in the Kharkiv Region and to analyze effects of some technological factors (namely, forecrops and sowing rates) on winter rye yield.
Materials and research methods. We used data of the statistical collection “Silske Hospodarstvo Kharkivskoi Oblasti (Agriculture of the Kharkivska Oblast)" and the statistical bulletin "Osnovni Ekonomichni Pokaznyky Vyrobnytstva Produktsii Silskoho Hospodarstva v Silskohospodarskykh Pidpryiemstvakh (Major Economic Indicators of Agricultural Production at Agricultural Enterprises)" as a starting basis. The main methods of analysis were summarizing statistical data, absolute and relative values, mean values, variations, dynamics series, tabular and graphic methods. The following methods were used to analyze the influence of forecrops and sowing rates on the yield: field surveys, determination the winter rye yield structure, measurements of plant growth and development, determination of yield, phenological observations; mathematical and statistical methods to test significance of results (variance analysis, correlation analysis).
The discussion of the results. From 1990 to 2021, the largest areas on the farms in the Kharkiv Region were sown with winter rye in 1990 (17,218 hectares), and the smallest (1,900 hectares) – in 2018. The economic theory says that area is an extensive factor in grain production development. Its mean value over the studied period was 7,102 hectares. The fluctuation degree of the winter rye-sown area in absolute units was very high, as evidenced by the coefficient of variation of 65.6%. The winter rye yield experienced the smallest fluctuation (coefficient of variation 24.5%), ranging 15.4 cwt/ha in 2010 to 38.3 cwt/ha in 2020. We believe that this is not a very good sign, because within 32 years reserves for increasing yields of this crop (indicator of intensive development, i.e. production growth solely at the expense of increasing the productivity of a unit of land area) could have been invented. In 1990, 17,218 hectares were sown with winter rye in the Kharkiv Region, which was by 8.3 times larger that the winter rye-sown area in 2021. During the investigated 32-year period, the winter-rye sown area decreased annually by approximately 610 hectares or 9%. The linear regression model of the post-sunflower sown winter rye yield dependence demonstrates that with an increase in the sowing rate from 4 to 5 million seeds /ha, we get a gain in the yield of 2.7333 cwt/ha. It turned out that with an increase in the sowing rate to 6 million seeds/ha, the yield decreases by 4.1 cwt/ha.
Conclusions. The winter rye grain production intensification should be associated with outpacing rates of yield growth compared to the growth of costs for ensuring this yield growth. Analytic quantization of the dynamic series of winter rye yields by 4th degree polynomial showed that with a probability of 0.95 we could note periods of decline in theoretically expected yields from 1990 to 2005 (from 32.2 cwt/ha to 18.3 cwt/ha) and from 2016 to 2019 (from 31 cwt/ha to 27.44 cwt/ha). We also have periods of rising yields in 2010-2015 (from 21.6 cwt/ha to 31 cwt/ha) and in the last two years (2020-2021) (from 30.4 cwt/ha to 38.5 cwt/ha). We do not recommend safflower as a forecrop in winter rye production, since it decreases yields because of lower moisture content in the soil is caused by a higher density of safflower plants and later harvest times compared to sunflower. Safflower is the most appropriate forecrop in spring cereal cultivation.