Normalized differential vegetation index of winter rape depending on different rates of nitrogen fertilizers with the combined use of a nitrification inhibitor

Abstract

Goal. To determine the relationship and actual correlation between the level of the normalized differential vegetation index (NDVI) and the yield of winter rape seed under the combined use of different rates of nitrogen fertilizers in the form of KAS-32 and the nitrification inhibitor (NI) 3,4-dimethyl pyrazole phosphate. Methods. Field (stationary experiment), laboratory (agrochemical analysis of soil and plant samples), analytical (systemic analysis of long-term field experiment results and meteorological observations), mathematical-statistical, correlation and regression analyses, mathematical modeling, and empirical generalization of the established patterns. Results. NDVI (in an average of 3 months) in the variants of the experiment was higher in 2018 (0.43–0.52), the yield of winter rape was also at the highest level in 2018 (3.12–3.85 t/ha). In the other 2 years of research (2020 and 2021), NDVI (averaged over 3 months in the variants of the experiment) was lower compared to 2018 and was 0.38–0.45 in 2020, and 0.36–0.41 in 2021. The yield of winter rape was also at a lower level in 2020 and 2021 of the research compared to 2018, in 2020 it was 2.21–2.98 t/ha, and in 2021 — 2.11–2.70 t/ha. Conclusions. It was established that the correlation coefficient of NDVI with the productivity of winter rape was high (0.95–1.0) for measurements in April in all variants of the experiment and for all years of research.