Burley mechanization efforts focus on both harvesting machines and cured-leaf removal systems or aids to reduce the hard work and improve labor efficiency. The traditional harvesting of burley tobacco requires intensive hand labor, resulting in a significant cost to the grower. As more mechanization options are becoming available, growers can choose equipment that will work best for their particular acreage and location. As growers and equipment manufacturers gain experience with existing and new machinery, improvements will be made to increase overall efficiencies. The following information discusses the high-tensile wire curing structures and cured leaf stripping aid. Contact your local Cooperative Extension Agent for additional information and available plans.
Portable Curing Frames and Field Curing Structures
Traditional harvesting requires spiking five to eight plants onto a stick and handling the plants and sticks. The 30- to 35-pound sticks are handled multiple times during loading and transporting from the field to the barn. In comparison, using portable frames can significantly reduce the labor required during harvesting. A portable frame provides a place to hang each plant as it is harvested. The heaviest unit to be handled by hand is a single plant, and the number of times a worker has to handle each plant is reduced. Tobacco cured on the portable frames has shown quality equivalent to that cured in conventional barns.The earlier frames developed used two legs and were stacked front to back against each other in the field to provide support. One design modification incorporates four removable steel legs per frame that provide greater stability and portability. Also, the removable legs simplify stacking of the empty frames and minimize the space required during storage between seasons. The portable frame incorporates a 6-inch by 6-inch wire grid from which the harvested plants can be hung. The frame dimensions are approximately 6 feet wide by 12 feet long and 7 feet tall. Approximately 264 plants are hung per frame, and depending on the field plant population, 25 to 30 frames will be required per acre. Because the frames must be loaded with plants in the field, a carrier unit was developed that is pulled behind a tractor. The frame full of tobacco remains under waterproof covers or under a shed until curing is completed. The curing environment can be managed by raising or lowering the side covering, but depends largely upon the weather.
Some growers developed low-cost and low-maintenance field curing structures that utilize high-tensile wire for hanging and curing the plants. Various construction methods and materials are being used. All structures incorporate, as they should, some type of plastic cover to protect the tobacco from the wind and rain. Although weather conditions greatly affect the cure quality, growers can manage the process to some degree by raising and lowering the plastic. Most of the low-cost structures use single wire strands that span support posts. The wires are spaced across the structure in 6-inch increments, and the plants are typically spaced 6 inches apart along the wire.The resulting plant density is approximately four plants per square foot, which is recommended for adequate ventilation. The height of the field structures should be sufficient to ensure the tip leaves are 6 to 12 inches above the ground. When constructing these types of field structures, do not exceed the tensile strength of the wire. Typically, 12.5 gauge high-tensile wire is used that has a wire diameter of approximately 0.095 inches and a tensile strength of 180,000 pounds per square inch (psi). http://www.bae.ncsu.edu/