The development of the technology of today and tomorrow has been either made possible or accelerated by the ongoing evolution of com­puters. The scientific breakthroughs of the space program have ushered in an era of nearly instant communications that link people and compa­nies worldwide. Researchers have machines, apparatus, and techniques available for their use that early pioneers in science could have never envisioned. Growers now press buttons to mix soil rather than lift shov­els. They let sensors determine when to water rather than sticking their fingers into the soil. Golf course superintendents consult their on-site weather station to determine the advisability of applying chemicals or preparing work schedules. No listing of the ways that computer-based technology is used throughout the green industry could ever be com­plete or current, but consider these several examples as representative.

The Greenhouse Industry

Enlisting the speed and alertness of computers to help grow plants in greenhouses has been made possible by the development of sen­sory input devices. Independent of human commands, the sensors can detect and monitor temperatures, light, humidity, carbon dioxide, wind velocity and direction, soluble salt levels, pH, and many other growth – related factors. The computerized control system does three things:

1. Sensing: The system objectively measures environmental factors using a series of independent sensors. The sensors are located both inside and outside the greenhouse range. They are not restricted to single locations within a house, which makes them a significant improvement over older, analog control systems.

2. Decision making: An independent computer monitors the sensors, analyzes the data they provide, and compares the existing environ­mental description against the grower’s programmed instructions.

3. Taking action: The system activates equipment within the green­house to implement the decisions made.

Computerized environmental control systems are component sys­tems whose parts are linked together by coaxial cables and computer chips, and whose data can be made available to the grower at any time, either in graphic displays or in digital or printed form by means of the computer monitor. Figure 26-8 illustrates a typical computerized envi­ronmental control system in a greenhouse range.

• reports sensor input and activates output devices to modify the environment

figure 26-8. Typical greenhouse computerized environmental control system (Courtesy of Timothy Toland)

Unlike older greenhouse control systems, which are basically reac­tive systems (example: the temperature drops below a minimum and the thermostat turns on the heat full force to warm the house), comput­erized systems can be programmed to respond almost continuously to the integrated sensory information. The result is a greenhouse environ­ment that remains nearly constant, changing more slowly than the reac­tive systems. Temperature extremes, crop drying and watering, humid­ity levels, light conditions, and other growth factors adjust gradually. The assumption is that this stability results in less traumatic growing conditions and thereby improves plant growth. Logical though the assumption is, researchers are just beginning to evaluate the new tech­nology. As computerized production technology continues to develop, it can be anticipated that such lags between manufacturer claims and independent confirmation will be common.

Representative greenhouse environmental control system manu­facturers are Argus Controls in Canada, Priva Computers, Inc. in the Netherlands, and Wadsworth Control Systems in Arvada, Colorado. It is interesting to note that none of the companies incorporates the word Greenhouse in their name, probably recognizing (and hoping) that their computer-operated systems have a more comprehensive adaptability to other and future green industry operations.