Hemp is harvested for seed production when the plant on being shaken sheds most of its seed. This occurs when the seeds are fully mature on the middle branches. The seeds will mature on the lower branches first and on the top of the plant last. The common method Hemp is harvested for fiber production when the male plants are in full flower and are shedding pollen. By harvesting before the male plants die, the retting of both male and female plants is more uniform, as both types of plants are still green and growing. The harvesting period may extend for 2 weeks or longer. Very early harvested hemp may produce a finer and softer fiber than that harvested later, but it is usually weaker. The fiber from hemp that has been harvested so late that many seeds have matured does not possess so good cordage and textile characteristics as fiber from hemp harvested earlier. Hemp stalks should be relatively free of leaves except a few at the very top before harvesting. This is important when hemp is shocked after harvest, as it makes the top of the shock smaller so that less rain can enter the shock. Harvesting methods vary with locality and climate. In Kentucky, hemp may grow to a height of 15 feet or more. These long stalks are difficult to handle with machinery. Self-rake reapers (see below) have been used in harvesting hemp for many years, and they probably do better work with very tall hemp than any other machine now available. A modified rice binder, which cuts and In the northern part of the Corn Belt the hemp usually does not grow so tall and therefore can be handled more easily with machines. During the first World War hemp-harvesting machinery was developed. These harvesters (see above) in one operation cut an 8- or 9-foot swath and elevate the stalks to a quarter-circle platform where they are turned automatically and dropped or spread on the ground for retting. The butts of the stems all lie in the same direction and are relatively even. The thickness of the layer of stalks in the swath influences the speed and uniformity of the dew retting. Machines of this type, because of their labor economy, are recommended for use in the Northern States, where hemp can be safely spread for retting when harvested. Hemp harvesters are usually owned by the hemp mills. They are rented to the individual farmers, who usually furnish the motive power and the labor to run the harvesters. |