February 29, 2008

Recent storms damaged or destroyed numerous tobacco housing and curing facilities across Kentucky. Whether to replace a facility and what type of facility to rebuild are important decisions for tobacco producers.

Several options for new and replacement tobacco barns, as well as field curing structures, are available, said George Duncan, extension agricultural engineer emeritus with the University of Kentucky Cooperative Extension Service.

“With labor becoming more scarce and costly, laborsaving features are a must,” he said. “Rising material and construction costs continue to increase the initial investment costs.”

It is important to build the most suitable facility for present and future production methods, Duncan said. Possibilities of future mechanical harvesting affect whether a facility can be modified, will become obsolete soon, or is needed at all. Farmers considering replacing barns have several options to consider including the following:

• The basic three- or four-tier durable barn designs for greater capacity but more barn labor.

• Two- or three-tier economy designs for competitive costs but with labor savings.

• One-tier field structures for lowest cost, smallest crew size, less total labor, more management of coverings, higher risk and no facility insurance coverage.

• Portable frame methods associated with mechanical harvesters.

To help farmers in their decision making, more than three dozen designs and plans are available on UK’s Department of Biosystems and Agricultural Engineering Web site. Updates showing cost comparisons and labor requirements have been added. Curing facility initial costs can range from $1,000 to $1,500 per acre capacity for simple field curing structures with plastic covers to $6,000 to $7,000 and more per acre capacity for conventional air cure barns, Duncan said.

The useful life of these structures can vary from 7 to 10 years for low cost field structures to 50 years or more for well-built barns. Labor requirements for hanging tobacco in these facilities (not including harvesting and hauling) can vary from approximately 12 worker-hours per acre of capacity up to 30 to 35 worker-hours per acre.

After deciding to replace a structure, producers may want to reevaluate the location to ensure it is in the best place to properly cure their tobacco crop.

A barn should be located in an open, well-drained area with the broad side facing the prevailing wind to provide the best cross ventilation. The best location is on a high point in the field or farmstead, Duncan said.

Width is the most important dimension affecting ventilation since width determines the distance the air must move as it passes through the facility and the amount of tobacco the air must pass through. Most traditional barns have been 40-foot wide and as long as needed to hold the desired amount of tobacco. Other designs are 32-foot and 48-foot wide. Any 48-foot wide barn needs good sidewall ventilation to ensure good curing. Lumber of sound quality and proper strength capabilities should be used for construction as shown in typical plans.

For labor saving in housing, the “sheds” within a facility should have driveway doors so transport vehicles can pass under the tier rails for efficient handing of tobacco up into the tiers, he said. Ventilator openings should be doors or panels, generally vertical, equivalent in area to at least one-fourth to one-third of the side wall area. Some barns built with metal siding do not have adequate side wall ventilation. Inadequate ventilation will result in “houseburn” during humid weather and with tightly spaced tobacco.

Lower cost plastic covered field structures can use untreated wood for reduced life or preservative treated for longer life. Various wooden and high tensile wire designs exist for stick harvested or notched plant hanging and curing. Careless and haphazard construction can result in failure of these structures when fully loaded with harvested tobacco, or when strong winds occur. Facility location can be on the downwind side of trees or other shielding to give some protection from strong winds, yet permit good ventilation for curing.

No one facility will work for every tobacco grower, Duncan said. Each producer must evaluate his present needs and future plans then determine what will best suit his operation.

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