Soil properties effecting yield formation in sugar beet under ridge and flat cultivation

Field trials were conducted in 2006 and 2007 on a sandy soil (Uelzen county, Lower Saxony, Northern Germany) to examine the influence of soil properties as effected by ridge compared to flat cultivation on the growth of sugar beet. Mean daily soil temperature between sowing (mid-March to mid-April) and May (4-6-leaf-stage) was 7.0 °C in the ridge and 6.1 °C in the flat cultivated soil. In May, total plant dry matter yield (DMY) was 38.7% higher in ridge compared to flat cultivation. Correlation analysis revealed soil temperature as the most important factor effecting early growth. Between May and June (canopy closure), ridge cultivation significantly increased crop growth rate (CGR) like in the period before, but the influence of soil temperature on plant growth diminished and penetration resistance correlated most closely to CGR. In June, DMY increase due to ridge cultivation was 29.7%. During the second half of the growing season, no significant differences in CGR due to cultivation occurred. However, yield was higher in the ridge cultivation treatment until final harvest in October, when white sugar yield (WSY) was increased by 8.4% compared to flat cultivation. It was concluded that the basis of higher final WSY in ridge cultivation was established during early growth until June, primarily caused by warmer soil and growth stimulating soil structure.