Sugar beet response to different K, Na and Mg ratios in applied fertilizers

Potassium (K) in sugar beet can be partly replaced by magnesium (Mg) and sodium (Na). This hypothesis was verified based on 12 field experiments conducted on four farms in Poland during the seasons 2010-2012. The effect of different K, Na and Mg ratios in fertilizers applied in the total rate of 3205 mol/ha on beet yield (BY), storage root quality and white sugar yield (WSY) was determined. The tested K: Mg: Na cation ratios were as follows: 1: 0: 0; 1: 0.11: 0.09; 1: 0.16: 0.54 and 1: 0.33: 2.19. BY and WSY were affected by the total rate of the applied cations. The optimum ratio of K: Mg: Na was different with respect to the site and the growing season. The K rate reduction from 125 to 24 kg/ha combined with the simultaneous increase in the rate of Mg and Na did not result in lower BY. However, a too narrow K: Na ratio in applied fertilizers resulted in a decrease of sucrose content in storage roots. The fertilization cost for sugar beet production could be reduced through the application of fertilizers that contain fixed amounts of Na on soils rich in available K.