Recently, I touched on potential challenges for long-term sustainability of intensive mono-crop situations (Inside View, January 2008). However, given immediate market pressures, let’s look at what’s happening with environmental control systems to maximize output and efficiency.
Sampling what’s new. Argus recently released new generation products for climate, irrigation, and nutrient control: the “Titan” system. Designed to co-ordinate control of all types of equipment, new features include almost unlimited expansion possibilities, individually customized user interface, enhanced flexibility and full-featured monitoring, alarm, and data-recording.
Currently, growers use “overdrain” measurements and calculations to monitor plants’ stress and crop evaporation rates. Measurements include:
• Overdrain percentage, EC, pH (measured in an overdrain “tray”).
• Moisture content percentage (measured by a “Groscale”).
• Plant temperature measured by infra-red camera.
Using plant temperature, the vapour pressure deficit (VPD) is calculated; perfect for controlling irrigation and misting systems in propagation.
New Priva software (‘Root Optimizer’) links together draintray and “Groscale,” automatically adjusting growing medium moisture content for optimum growth. For example, when the draintray measures first actual drain of the day, “Root Optimizer” automatically re-calculates moisture content to 100 per cent, making decisions much easier.
Other companies are developing plant sensor equipment. Hoogendoorn has introduced its “Stomata Sensor” system. Rather than measuring indirect influences of growth (i.e., greenhouse environments, irrigation), “Stomata Sensor” measures plant transpiration directly, so growers can “listen to the plants.” Together with closed or semi-closed greenhouse systems such as “Aircokas,” this may provide opportunities for 10-15 per cent higher yields.
What’s the future? “Smart” greenhouse equipment. Increasingly, greenhouse equipment systems contain their own micro-processors, notably in package boiler systems, variable frequency drives, and so-called “smart” valves and fans. These often have their own sensors and are capable of automatically modifying their operating behaviour for maximum efficiency and reduced wear. Some accept external input and generate output information. To ensure proper operation and overall integration with other controlled equipment and processes, interfacing to such systems requires central control systems to be flexible.
“Smart” equipment is typically more expensive than standard alternatives and “intelligent” features may be redundant when equipment is operated by an integrated control system. Argus recommends that when considering installing equipment with enhanced capabilities, your controls supplier should be involved to ensure that full benefit from these extended features is achieved.
Software supervisory control capabilities: The grower normally decides climate and irrigation targets in the
greenhouse. Soon, it may be possible for targets to be set and adjusted using artificial intelligence (“AI”). Growth models and other software programs can constantly monitor crop progress and adjust growth parameters for optimum production. This requires integration between these models and existing greenhouse climate control systems.
With the recent release of the “Supervisory Control Guardian” (SCG) program and data exchange features, Argus has adopted an “open systems” approach to working with crop models. AI system developers can use greenhouse sensor readings and other Argus system output data as inputs to their models. In turn, the control system can receive “course correction” data from the models to adjust control targets. The “SCG” program ensures that data being received is up to date and within safe operating limits. This information can then be used to change climate set-points or other control corrections.
Benefits of this approach are that developers of AI systems are free to develop core models without worrying about the complexities of data acquisition and equipment control. Regardless of the current status of the AI program or its decisions, the control system will continue to operate equipment efficiently, effectively and within safety limits.
Wireless study groups. Staying with computers, the greenhouse industry is becoming increasingly consolidated, with fewer but bigger operations. Hoogendoorn sees this as timely to develop more web-based software or remote management, and anticipate more control equipment linking directly with Internet study groups (e.g., “Let’s Grow Live”) for crop monitoring and performance comparison.
Greenhouse fuel production? Priva engineers foresee the potential for greenhouse production of bio-fuel. Currently ethanol crops are in development and testing on over 4,000 acres field production, but high-intensity hydroponic greenhouse production may have potential. The world may ultimately depend on it!
Gary Jones is chair of production horticulture at Kwantlen University College and serves on several industry committees. He can be contacted at