The aim of this study was to determine the effect of organic leaf fertilization on the chemical composition, nutritive value, yield of crude protein (CP) and feed units of natural Agropyron repens grassland in the region of South-Central Bulgaria (305 m altitude). The experiment was carried out with leaf organic fertilizer Naturamin Plus, during the period 2018-2019. The trial was designed by the block method in 4 repetitions and 3 doses of fertilizer were tested: 1500; 2500 and 3500 ml/ha. The obtained results were statistically processed by ANOVA. The applied leaf organic fertilizer Naturamin Plus promoted a positive effect on the productive parameters of natural Agropyron repens grassland but had no significant effect on the chemical composition and nutritive value of the harvested biomass. The results demonstrated that yield of CP, feed units for milk (FUM) and feed units for growth (FUG) increased significantly by fertilization with a dose of 2500 ml/ha -respectively 22.2%, 29.7% and 29.4% more compared to the control.

During three year period at the Agricultural Institute, Stara Zagora (Bulgaria), influence of fertilization with Nitrogen, Phosphorus and Molybdenum alone and in combination on the energy efficiency of winter faba bean variety Meris Bina was investigated. In the experiment the next variants were included: 1. unfertilized; 2. N 60 ; 3. Р 120 ; 4. N 60 Р 60 ; 5. N 120 Р 120 ; 6. Мо 0,2 ; 7. N 120 Мо 0,2 ; 8. Р 120 Мо 0,2 ; 9. N 120 Р 120 Мо 0,2 . It was established that the examined variants of mineral fertilization have positive effect on obtained biomass and energy efficiency of the production. The highest coefficient of energy efficiency was obtained from fertilization with Molybdenum (Мо 0,2 ) alone-13.63 for GE; 7.49 for ME and 4.43 for NE, which was respectively with 13.,05%, 13.73% and 13.85% higher compared to the unfertilized faba bean.