Evaluation of the Relationship between the Yield and Grain Quality of Winter Wheat and the Fertility Indicators of Typical Chernozem

The study was conducted to evaluate the relationship between yields and grain quality of winter wheat and soil fertility indicators and determine their optimal values for the crop using infological analysis. The work was carried out in 2021–2022 on typical chernozem in Kursk oblast. Conjoint studies were conducted on the yield and protein content in the grain of winter wheat of the Leonida variety as well as soil fertility indicators in the 0–20-cm layer on a 30-m area during the harvesting period. A stable very close, close, and medium-strength relationship was revealed between the winter wheat yield and soil density (information transmission coefficient 0.42 in 2021 and 0.18 in 2022), content of exchangeable calcium (0.18 and 0.36), microbial biomass as % of mobile humic acids (0.31 and 0.26) and of humus (0.28 and 0.15), humus (0.20 and 0.15), mobile phosphorus (0.20 and 0.13), quality of mobile humus substances (0.19 and 0.13), and the Ca/Mg ratio (0.14 and 0.21). Similar correlations were established for the protein content in grain with mobile humus substances (0.31 and 0.15) and mobile fulvic acids (0.23 and 0.19), alkaline-hydrolysable nitrogen (0.12 and 0.09), mobile potassium (0.06 and 0.17), soil density (0.17 and 0.25), Ca/Mg ratio (0.17 and 0.25), and mobile phosphorus (0.15 and 0.08). Optimal and integrated optimal soil fertility indicators were established for the formation of winter wheat yields of 3.3–5.3 t/ha with protein content in grain of 16.9–17.9% in 2021 and yields of 7.1–8.6 t/ha with a protein content of 11.8–12.3% in 2022. Over the study years, stability in the formation of the winter wheat yield was characteristic of the values of the optimal parameters of soil density (1.1–1.2 g/cm3) and the quality of mobile humus substances (0.74–0.86), while protein in grain by content of mobile humic acids in soil as a percentage of humus (5.4–5.9%), soil density (1.10–1.22 g/cm3), and mobile phosphorus (150–157 mg/kg).