Computer environmental control systems provide efficiencies By Kelli Rodda throughout

Computer environmental-control systems provide efficiencies By Kelli Rodda throughout the greenhouse Environmental controls wish list port, said John Korns, research facilities administrator at the university. The $16 million greenhouse range was completed last fall. It’s home to research interests such as plant breeding, phytoremediation, transgenic plants and weed and insect control. The range is equipped with a Priva environmental-control system, a fertilizer-injection unit and a fully equipped lab, growth chamber facilities and a rooftop weather station. Best management practices (BMP) are the foundation of the new greenhouse design and construction, according to the university. Ongoing BMP research will provide critical and cost-saving information to the greenhouse industry. Environmental controls keep the indoor environment running smooth despite extreme cold, like the Scotts Co. research facility in Marysville, Ohio. A re you getting the most out of your greenhouse environment? Growers pride themselves on instinct and having an eye for detail, but an environmental-control system can be the copilot. The system can save on labor, water and energy, which translates into cost savings and a better crop. When the University of Maryland began planning its state-of-the-art research greenhouses, the environmental controls had to equal the facilities in terms of abilities and sup- Better control equals better crops The Priva system controls a multitude of functions, including heating, cooling, irrigation, supplemental greenhouse gems Manipulating Mother Nature There you stand in the middle of your Ultimate Greenhouse structure gazing up at the sun shining through the ultimate glazing, thinking you now have the ideal facility to grow the best crops you’ve ever produced. But once your plants are inside the structure, how are you going to maintain the ideal environment? Making sure that your plants receive optimum levels of light, carbon dioxide, nutrients and water are critical to producing a quality crop in the fastest time. So this month we look at the Ultimate Greenhouse Environmental Controls system. This is the fourth in a 12-part series that will discuss the “what if,” with comments from industry representatives about what they think the ultimate greenhouse would (and could) look like. You, too, have the opportunity to tell other GMPRO readers about your ultimate greenhouse at www.greenbeam.com and in our Green(house) Dreams contest. Optimum conditions for Botrytis growth are temperatures of 64°F-82°F and high humidity or free moisture. Free moisture occurs when plant tissue temperature drops and relative humidity is high. This is most often just after sunset when plant tissue temperatures drop more rapidly than air temperatures, or in the morning when air temperatures rise quickly. If the greenhouse environmental controls are not quick enough to respond to these changes, Botrytis can become established. Warm air has a higher moisture-holding capacity than cooler air. As the air temperature increases, the relative humidity decreases even though the amount of water remains constant. Air at 70°F holds twice as much moisture as air at 50°F. Achieving the “ultimate” in environmental control for greenhouse production means being able to reproduce perfect climates for growing plants, said Alec Mackenzie, general manager at Argus Control Systems in White Rock, British Columbia, Canada. This begins with rethinking the structures and it carries through to the choice of greenhouse equipment and environmental control systems, he said. The ultimate environmental-controlled greenhouse would be able to correct any growth parameter that is out of balance with the current needs of the crop. Although people think of greenhouses as controlled environments, most do not have full control over all of the factors of growth. There is a continuing need to design better equipment that can deliver precision amounts of the desired effects they produce, he said. “Many have spoken of the ‘talking plant’ as the coming model for greenhouse control,” Mackenzie said. “The idea is that the plants would be able to tell us what they need, through monitored feedback of their physiological processes. While this is an excellent concept, it has been difficult to put these notions into commercial practice due to the cost and reliability of suitable sensing mechanisms and the problem of selecting representative plants.” Plant modeling may take this a step further in the future by mathematically predicting the current needs of a crop from previously studied representative plants, he said. This could help to avoid the sorts of measurement errors that can plague live feedback systems. x For more: Argus Control Systems Ltd., 1281 Johnston Road, White Rock, British Columbia, Canada V4B 3Y9; (800) 6672090; www.arguscontrols.com. Natural ventilation is easily managed with environmental controls systems. Sensor placement is important to correctly feed information to the environmental control system. Virtual control W TC Engineering Inc. in Bozeman, Mont., took the greenhouse into a virtual world. Its ICON environmental-control system is accessible via the Internet. Automatic adjustments of temperature, humidity, lighting, watering, fertilizer, carbon dioxide levels and other parameters create WTC’s ICON environmental control optimal and stable growing conditions while system is accessible via the Internet. saving costs on labor, energy, and wear and tear of equipment, said Kathi Swingle, vice president and general manager of WTC. “Data collection and history trending help you determine optimal growing conditions,” she said. “The alarming system alerts you to problem areas either via visuals, sound or e-mail. The same quality and reliable environmental-control system the greenhouse industry has grown to love is now accessible via the Internet.” The Internet-based system gives growers a bit more freedom because they can view any problems or changes from the Web. “If an alarm sounds, growers can check the system from the Internet, whether at home or on the road, and it could save them a trip to the greenhouse,” she said. ICON also has PDA capability. The system can be customized, such as changing the screen layout, adding or deleting controls and using time-based or solar-based control. x For more: WTC Engineering Inc., 2000 Fairway Drive, Bozeman, MT 59715; (406) 5861511; www.wtceng.com. tips on-the-run 18 GMPRO April 2004 A plant grown under a maximum light intensity of 3,000 footcandles in June will receive considerably more light than a plant grown under a maximum light intensity of 3,000 footcandles in December simply because the daylength is much longer in June. Antidrip treatments lower the coefficient of friction on the surface of glazing material. The treatment ensures condensation sheets off in an even film and is not allowed to form into a droplet. A physical weed mat barrier helps prevent both weed and algae growth. Avoid using stone on top of the weed mat. This will trap soil and moisture, creating an ideal environment for weeds, diseases, insects and algae. Buy fuel in summer when it is more abundant and cheaper to help with next winter’s fuel bill. w w w. g r e e n b e a m . c o m w w w. g r e e n b e a m . c o m April 2004 GMPRO 19