The present study aims to investigate how fertilization levels impact the partial factor productivity of nitrogen, phosphorus, and potassium in triticale. The experiment was set up in four repetitions on the experimental field of the Agricultural University of Plovdiv for three years after the predecessor sunflower. The field trial included three triticale varieties: Kolorit (standard), Trismart, and Musala grown at two fertilization levels N60P50K20 and N120P100K40. Fertilization levels significantly affected the partial productivity values of nitrogen, phosphorus, and potassium, either separately or in total, regarding the productivity of grain and grain protein in the three triticale varieties. The average partial productivity of nutrients over the study period decreased as the level of fertilization increased. For each unit of nutrients applied, less grain or grain protein was produced at higher fertilizer rate compared to a lower one. Specifically, the results from the double fertilization rate of N120P100K40 showed that the efficiency of each kilogram of nutrient imported was lower. The average partial productivity of applied PFP-NPK nutrients was higher at the low N60P50K20 fertilization level. The climatic conditions during the triticale vegetation had a significant effect on the partial productivity of nitrogen, phosphorus, and potassium for grain yield. Тhe lowest values of the partial productivity were found in the variety Trismart grown at N120P100K40 level in the unfavourable climatic 2017. The productivity of all three elements was highest in the variety Musala, fertilized with N60P50K20 in 2019. Unfavourable conditions in 2017 reduced the partial productivity of nitrogen for grain by 40.0 kg kg-1 at the level of N60P50K20 and by 15.6 kg kg-1 at N120P100K40. Drought resulted in lower grain production per unit of phosphorus and potassium applied.
Georgieva et al. (Tue,) studied this question.