Qualitative state of chornozems of the Chkalovsk community in the pre-war period

Goal. To establish the relationship between meteorological data, the level of the normalized differential vegetation index (NDVI) and the yield of winter wheat, winter rape, and corn using different doses of nitrogen fertilizers in the form of KAS-32 and the nitrification inhibitor (NI) 3,4-dimethylpyrazole phosphate (DMPP). Methods. Field (stationary experiment); laboratory (agrochemical analysis of soil and plant samples); analytical (systematic analysis of long-term results of field experiments and meteorological observations); mathematical-statistical; correlation and regression analyses; mathematical modeling and empirical generalization of established patterns. Results. The average daily temperature, the sum of active temperatures, and the amount of precipitation over the years of research (2018–2021) did not harm the yield of winter wheat, winter rape, and corn. NDVI and yield increased in the experimental variants with an increase in the nitrogen dose and the use of IN and subsequently decreased slightly in the experimental variant with the maximum dose of nitrogen fertilizers, but without the use of IN in each of the studied years. On average, over the 2018–2021 studies, the yield of winter wheat increased from 3.74 to 6.27 t/ha in the control variant N10P30K40 (background), and to 6.30 t/ha in the variants: background + N100 + IN, and background + N120 + IN; and subsequently decreased to 5.85 t/ha in the experimental variant with the maximum dose of nitrogen fertilizers, but without the use of IN (background + N120). The yield of winter rape increased from 2.48 to 3.06 t/ha in the control variant N10P30K40 (background), and to 3.16 t/ha in the variants: background + N120 + IN, and background + N130 + IN, and decreased to 2.79 t/ha in the experimental variant with the maximum dose of nitrogen fertilizers, but without the use of IN (background + N130). The yield of corn also increased from 8.14 to 9.75 t/ha in the control variant N10P30K40 (background), and to 9.52 t/ha in the variants: background + N120 + IN, and background + N130 + IN, and decreased to 8.97 t/ha in the experimental variant with the maximum dose of nitrogen fertilizers, but without the use of IN (background + N130). Conclusions. It was found that during the research years (2018–2021) weather conditions did not harm the yield of winter wheat, winter rape, and corn. NDVI and yield increased in the experimental variants with an increase in the nitrogen dose and the use of IN and subsequently decreased slightly in the experimental variant with the maximum dose of nitrogen fertilizers, but without the use of IN.