KNOCKDOWN CAUSES MAJOR DAMAGE TO CANE DURING HARVESTING

摘要

Field observations and earlier research have shown that knockdown is responsible for damage to cane during harvesting. The paper investigates the bending of cane and shows that the ultimate strain of cane in bending is approximately 1.8% and independent of stalk diameter and variety. In firm soil, the knockdown and finned feed rollers in current harvesters will break and collapse the majority of stalks before the basecutters reach them. In loose soil the stool is rotated or lifted out of the ground resulting in damage to the root system. Most soil types allow some movement at the base of the cane, yet force the stalks to bend during knockdown. A single stalk/single cut apparatus was used to investigate cane behaviour when bent stalks receive a partial cut. Large splits, up to three internodes in length, occurred with a depth of partial cut approximately half the stalk diameter. For single cuts or a minimum of three partial cuts, the damage is restricted to the first node above and below the partial cut. Damage to the stalks is inevitable with current harvester designs, but can be reduced by altering operating parameters so that each stalk is cut by three or more partial cuts.