Abstract: The present invention entails a process for curing and drying tobacco and other related agricultural products. A three-mode controller having proportional, integral and derivative functions is utilized to actuate an inlet damper associated with a curing and drying structure. In order to compensate for outside environmental changes and dynamic changes within the structure, a proportional, integral and derivative tuning module is provided which continues to tune and establish new proportional, integral and derivative functions as the curing and drying process is moved up a temperature ramp.

Abstract: The present invention entails a method for curing and drying tobacco wherein the initial phase of the curing and drying process, that is the yellowing phase, is accelerated by the simultaneous application of ethylene and heat. In particular, the process of the present invention entails coloring the tobacco at a temperature range of 100.degree.-120.degree. F. and actually applying a concentration of ethylene to the tobacco while the tobacco is subjected to this coloring temperature range.

Abstract: A process for degreening and coloring tobacco by subjecting the tobacco to air containing ethylene gas and thereafter wilting, dehydrating and curing. The air containing ethylene gas is exchanged within a controlled environment at a substantially high rate to not only replenish the oxygen and nitrogen content, but also to remove the carbon dioxide generated in the coloring process that can inhibit further coloring. The process also permits increasing the temperature around the tobacco during the wilting and dehydrating stages so as to substantially decrease the total time required for curing the tobacco.