Impact of Irrigation and Fertigation on the Yield and Quality of Sugar Beet (Beta vulgaris L.) in a Moderate Climate

In Poland, under conditions of the moderate climate and transition between maritime and continental climates, the average rainfall totals of the growing season are in the range of 350-400 mm; however, they are distinguished by great temporal and spatial variability. Climatological studies demonstrate that the drought frequency is approximately 30%. Therefore, under such conditions, irrigation has a supplementary and intervention nature and is applied only when dry periods occur. The aim of this study was to determine the impact of sprinkler irrigation and increased nitrogen fertilization on the yield and quality of sugar beet roots and yield of sugar. The average increase of the yield under irrigation was 18.1 t.ha(-1) which constituted a 22.8% increase in the yield. Furthermore, there was a marked tendency of a higher sugar content in the roots of irrigated plants. The absolute, relative, and unit average sugar beet root yield increases obtained under the influence of sprinkler irrigation and the lack of a significant diversity in the sugar content in roots confirm that irrigation contributed to an appropriate pace of plant growth and development. The increased rate of nitrogen fertilization (N2) of 160 kg N.ha(-1) plus an additional 40 kg N.ha(-1) resulted in the significantly greater root yields compared to the control (N1) (160 kg N.ha(-1)), i.e., an average of 7.6 t.ha(-1) (9%). Based on the crop-water production function, the maximum root yields were obtained for the N1 rate at a total precipitation and irrigation amount of 382 mm, compared with 367 mm for the N2 rate.