SUGAR BEET RESPONSE TO BALANCED NITROGEN FERTILIZATION WITH PHOSPHORUS AND POTASSIUM PART I. DYNAMICS OF BEET YIELD DEVELOPMENT

K. Peplinski, P. Barlog, W. Szczepaniak, W. Grzebisz

Abstract: The objective of the conducted study was to determine the effect of various levels of P, K under the background of constant N rate on dynamics of sugar beet root yield. The field trial, arranged as a 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 N, P, K application and Ca means that phosphorus applied as partially acidulated phosphoric rock (PAPR). The in-season yield sampling was conducted at 92, 113, 134, 155 and 175th day after sowing. The highest degree of yield potential realization revealed in the year with favourable weather conditions. The highest yield was harvested on the plot fertilized with N1P1K1+Ca. In years with extended drought, sugar beet achieved the maximum yield in the treatment N1P0.25K0.25. Phosphorus revealed as the key yield forming factors, i.e., limiting N unit productivity. The maximum productivity of N occurred in treatments with full P rate, especially when P fertilizer was applied as the PAPR. However, phosphorus yield forming action depended on weather conditions in the mead-season and P fertilizer rate. The first factor, affecting N and K supply to sugar beet during the mead-season, was responsible for the size of the beetroot, considered as the sugar storage. Any drought, negatively impacting its size, in turn decreases P yield forming action, which appears in the late-season. The maximal exploitation of sugar beet yielding potential is, therefore, possible provided water is not a factor limiting sugar beet growth in the mead-season and P in late-season. Nevertheless, in farming practice, the lack of favourable growth conditions should not be a reason for development a sugar beet fertilizing strategy, based on reduced P and K rates.

Keywords: agronomic efficiency; balanced fertilization; beet yield; growth dynamics; partial factor productivity

Date published: 2019-01-17