P. BARŁÓG, W. GRZEBISZ, K. PEPLIŃSKI and W. SZCZEPANIAK
University of Life Sciences, Department of Agricultural Chemistry and Environmental Biogeochemistry, 60-625 Poznań, Poland
BARŁÓG , P., W. GRZEBISZ, K. PEPLIŃSKI and W. SZCZEPANIAK, 2016. Sugar beet response to balanced nitrogen fertilization with phosphorus and potassium. Part III. Dynamics of white sugar yield development. Bulg. J. Agric. Sci., 22: 197–204
The main objective of the study was to evaluate the dynamics of white sugar yield (WSY) by beet crop under conditions of imbalanced application of key nutrients, such as P, K with respect to N. The field trial arranged as one-factorial design was consisted of eight treatments: N0P0K0; N0P1K1; N1P0K1; N1P1K0; N1P0.25K0.25; N1P0.5K1; N1P1K1 and N1P1K1+Ca; where 1 is recommended level of NPK fertilization and Ca means that phosphorus applied as partially acidulated phosphoric rock (PAPR). The harvest of sugar beet took place at following days after sowing (DAS): 92, 113, 134, 155 and 175. Yield of white sugar was determined by set of standard methods used in a sugar beet factory. The course of weather was the dominant factor, affecting realization of yielding potential of a crop on the background of supply of P and K. Under favorable growth conditions, yield of sugar increased accordingly with increasing rates of fertilizer P. Yield forming effect of P, as a rule, revealed in the late-season, resulting in the WSY increase of 30–40% at 175 DAS compared to 155 DAS. The average yield increase in response to optimal application of P was 18.4%, whereas of K only 6.0%. In years with drought, the effect of P was low due to limited development of the storage root to accumulate sucrose. The main reason was a probably insufficient supply of N and K in the mead-season, restricting size of the root. Consequently, the optimum P rate to harvest sufficiently high WSY in years with drought was at the level of 25% of the P recommended rate. On the average, the maximum yield of WSY was harvested in N1P1K1+Ca treatment, indirectly indicating on an importance of Ca as a sugar yield forming nutrient.
Key words: sugar yield, dynamics of sugar accumulation, nitrogen, phosphorus, potassium, imbalanced fertilization