“The greenhouse must respond to weather conditions that change all the time”

The next time you sit down to a crisp green salad, take some time to think about where your leafy greens are coming from.

Traditional agriculture is highly dependent on weather conditions, and many growers of high-value crops are switching from open-field production to controlled-environment agriculture. This is where Marc van Iersel of the University of Georgia comes in.

Van Iersel, Vincent J. Dooley Professor of Horticultural Physiology at UGA’s College of Agricultural and Environmental Sciences (CAES), defines controlled environment agriculture, also known as CEA, as both greenhouse production which relies on natural sunlight and vertical trusses that use an electric light source.

Research by UGA horticulture professor Marc van Iersel focuses on developing sustainable, cost-effective ways to ensure that crops – such as these turnip plants in a grow room in his greenhouses – receive the amount light they need to grow. (Photo by Andrew Davis Tucker/UGA)

Responding to climate challenges
“One of the reasons a shift is happening is that 90% of all leafy greens produced in the United States are produced in California and Arizona. This area is in a mega-drought and there is no end in sight. Because of this, they may not really be able to have water available to grow crops in what is essentially a desert,” he said. Controlled-environment agriculture is attractive to growers who are “looking for production systems that may not use as much water under controlled conditions where you can get predictable production year-round.”

During his 27 years at CAES, van Iersel’s research has focused on developing sustainable and cost-effective ways to ensure that crops receive the amount of light they need to grow.

“The greenhouse has to respond to weather conditions that change all the time,” he said. “You have shorter fluctuations from morning to afternoon to evening and fluctuations throughout the year in many parts of the United States in the winter. You have to adapt to it. »

Based on his research, van Iersel co-founded Candidus – an agricultural technology company – in 2017 with Erico Mattos, who received his doctorate from UGA in 2013. The company provides lighting control systems that use a compact and powerful industrial microcomputer for monitoring light sensors. , calculate optimal lighting conditions and control lighting in controlled environment systems via a local Wi-Fi network.

“No one was taking advantage of the precise light control in greenhouses,” van Iersel said. “We found that we could reduce electricity costs for lighting by 30%, and given that, generally speaking, the cost of electricity for lighting is between 10 and 20% of operation of greenhouses, it can reduce operating costs by almost half. »

The partners initially developed a system that responded to real-time sunlight levels, but van Iersel worked with electrical engineers to improve the system.

Predict sunlight
“We are focusing on control algorithms through which we can now predict how much sunlight we are likely to get for the rest of the day, which helps us make better decisions about how much light we want to provide” , did he declare. “We have also developed algorithms that allow the lighting system to respond to changing electricity prices. You don’t have the same electricity price during the day. I believe the latest estimate from the Department of Energy indicates that the United States spends about $1 billion a year on electricity to provide light to crops that are grown in controlled-environment agriculture.

The responsiveness built into the Candidus algorithm has a significant effect on producers’ return on investment.

“You create a system that reduces the overall cost by 20% and makes a critical financial difference,” van Iersel explained.

One of the hardest parts of the job is convincing growers who have operated a certain way for decades that a new system can deliver real value to them. “Many are hesitant to switch things up, but some producers like to try new ways,” van Iersel said. “When you see more people succeeding after trying something, you tend to feel more comfortable.”

Management of hydroponic systems
In August 2021, Rhuanito Ferrarezi was hired as an Associate Professor of Controlled Environment Agriculture in the CAES Department of Horticulture to leverage his production expertise to help build research capacity in controlled environment agriculture.

A main area of ​​his work is improving irrigation, nutrition and cropping systems, focusing on vegetables and ornamentals.

“My lab is trying to figure out which management systems should be used in hydroponic systems for controlled environment agriculture,” Ferrarezi said. “We are also focusing on how we manage fertilizer solutions in a controlled environment to provide an advantage in using less fertilizer for production.”

“Like a blood test for a plant”
One of the innovations Ferrarezi is working on relates to sap analysis, which uses leaf samples or soil substrate sampling to determine nutrient content in plant tissue.

“It’s like a blood test for a plant,” he said. “We provide a snapshot of what is happening with the crop during a growth cycle. In a controlled environment, we have the ability to grow a crop faster than in the field. We can actually monitor the nutrient content inside a plant in real time and growers can increase or decrease fertilization based on those results.

Ferrarezi believes controlled-environment agriculture will continue to attract increased attention from industries, and with good reason.

“They’re looking for ways to refine production, and controlled-environment agriculture can help lead the way,” he said. “It’s an exciting time to work in this field.”

UGA is a member of a consortium of land-grant institutions in the southern region of the United States committed to finding workable solutions that preserve our natural resources, nurture a growing world, and improve our quality of life.

For more information:
University of Georgia
www.uga.edu

About Jefferey G. Cannon

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