Optimization of nitrogen, phosphorus, and potassium fertilizationfor maximizing root yield and inulin yield in chicory (Cichorium intybus L.)
Department Plant Science, National University of Life and Environmental Sciences of Ukraine, Heroiv Oborony Str., 15, UA03041 Kyiv, Ukraine
*Correspondence: mazurenko.bohdan@nubip.edu.ua
Abstract:
Root chicory (Cichorium intybus L.) is an important industrial crop for inulin production, but the optimization of mineral fertilization under fertile chernozem soils remains insufficiently defined. Under such conditions, additional fertilizer inputs may not proportionally increase root and inulin yield and may lead to higher residual nutrient levels after harvest. The aim of this study was to evaluate the effects of nitrogen and phosphorus-potassium fertilization on root biomass traits, crude inulin content, inulin yield, and post-harvest soil nutrient status of root chicory grown in the Right-Bank Forest-Steppe of Ukraine. A three-year field experiment (2021–2023) was conducted using a two-factor design with incremental PK and N rates. Cluster analysis and pairwise correlation coefficients were calculated between these parameters. The proposed approach to determining the optimal fertilizer rates for maximizing yield in individual years indicated values of N130P66K110, N150P60K100, and N120P72K120, with an average of N130P66K110. The highest inulin yield reached 5.80 t ha⁻¹, compared with 2.88 t ha⁻¹ in the unfertilized control. Crude inulin concentration varied less than biomass-related traits, indicating that industrial raw material output depended primarily on root productivity rather than on large changes in inulin concentration alone. Post-harvest soil analysis showed that nitrogen fertilization increased residual hydrolysable nitrogen, whereas PK fertilization mainly increased mobile phosphorus at higher application rates. Thus, optimization of chicory fertilization under fertile chernozem conditions should be considered not only as a strategy for maximizing root and inulin yield, but a way to improve nutrient-use efficiency and avoid unnecessary nutrient surpluses.
Key words:
Agro-ecology, cluster, correlation, model, nutrient