UPROOTING OF CANE STUBBLES BY MECHANICAL HARVESTERS

摘要

Mechanized harvesting of sugar cane has been identified as one of the most important means of reducing production costs in Mauritius. However, gappy stands have been observed in some trials with this mode of harvesting, mainly attributed to stubbles being uprooted by base cutter blades. Effects of two settings (ground level and 3 cm above ground level) of the base cutter on the extent of gaps were evaluated in 2001 and 2002 on cane varieties R 570 and M 695/69. Gaps equal to or greater than 60 cm were measured 12 weeks after harvest. In situ stool profile studies were conducted in fields that have been mechanically harvested for three years or more. Soil was excavated around the stool to observe the position and record the depth at which new shootsemerge. The root distribution was also studied. When base cutter blades were placed at ground level, the level of gaps with variety M 695/69 compared to variety R 570 increased by 2.7% and 5.8% in 2001 and 2002 respectively. With the other base cutter setting the increases were 0.9% and 1.5%. Observations of the stool profiles explain the difference in the behaviour of these two varieties. The position of emergence of new shoots, the depth of regrowth and the root distribution, which were studied also for varieties M 1658/78 and M 1176/77', are the main factors that contribute to uprooting of stubbles.