The Use of Slow-Release Fertilizers as a Part of Optimization of Celeriac Production Technology

The aim of this study was to assess the possibility of using slow-release fertilizers under intensive vegetable cultivation. To achieve the set research objective, a field experiment was set up in 2017, where slow-release fertilizer (NPK (%) 20-10-10+4MgO) was applied. The experiment comprised three levels of fertilization with the use of slow-release fertilizers, the control without fertilization, and the control fertilized with conventional fertilizers. The slow-release fertilizer was applied directly under each plant and in rows – approximately 8 cm below the root level. The designed systems were evaluated based on the size of commercial yield, productivity index, agronomic efficiency index, removal efficiency index, and physiological efficiency index. The results obtained in the field experiment indicate that the highest plant yield (54.22 Mg of commercial yield∙ha⁻¹) was obtained at the highest dose of slow-release fertilizers (600 kg∙ha⁻¹ applied in rows approximately 8 cm below the root level). In the case of direct fertilization, in the treatment with the highest dose of slow-release fertilizer, a reduction in yield was observed. The best results, in terms of equalizing the mass of individual roots, were obtained under conventional fertilization. The most favorable value of the productivity index was obtained in the variant where 400 kg∙ha⁻¹ slow-release fertilizer was applied directly, while in the case of row application the best results were obtained at the dose of 600 kg∙ha⁻¹. Celeriac fertilization with slow-release fertilizers under root may result in producing a yield of bigger differences in root mass, compared to conventional fertilization system.