Development of greenhouse solar systems for bulk tobacco curing and plant production

Among many farm crops, bright leaf tobacco is the most energy- and labor-intensive crop. The greenhouse solar system (solar bulk-curing/greenhouse system, or solar barn) was developed to provide multiple-use facilities for year-round solar energy utilization to save fossil fuels in tobacco curing and plant production and to facilitate the total mechanization of tobacco culture. Two types of full-size greenhouse solar systems, the load-supporting wall design and the shell design, both utilizing the thermal envelope concept, were designed and constructed for solar bulk-curing of tobacco, growing transplants and horticultural crops under controlled environment, and aiding automation of transplanting operations.

Full-scale field tests of solar bulk curing showed that the fuel savingswere consistantly improved from 37% in 1975 to 51% in 1978 for this solar bulk-curing system as compared with a conventional bulk-curing barn as a control. The feasibility of the system to save energy by using solar energy as a first priority source was significantly demonsrated. Three-year greenhouse and field tests showed that high germination rate of 95–97% with excellent emergence frequency was obtained for tobacco seeds under the controlled environment provided by the greenhouse solar system. In general, the containerized transplants from greenhouse solar system significantly exceeded the conventional bare-root transplant in growth, leaf-quality and yield.