Affordable, Image-Based Crop Monitoring Using Smartphones and Microcontrollers

Smart Sensors From Purdue University

With a mission to deliver easy-to-use, rapid and affordable technologies to the controlled environment agriculture (CEA) industry, Dr. Krishna Nemali and his research group at Purdue University are tackling crop-monitoring challenges facing hydroponic and flower growers. Of the group’s many research foci, image-based crop monitoring using smartphones and microcontrollers has been at the forefront of Purdue’s technological advancements for the CEA industry.

Image-based crop monitoring made practical and affordable
Image analysis is being used for monitoring plants in conventional, field-based agriculture through satellites, drones, and camera-mounted vehicles. However, these technologies are not practical for greenhouses and indoor farms due to the architecture of these facilities, which limits the movement of drones or camera-mounted vehicles over plants. Dr. Nemali and his research group are working to bring image-based crop monitoring on smartphones as handheld sensors. For installations where using cameras fixed to the growing systems is preferred (e.g. vertical farms with multi-tiered racking) or applications where continuous monitoring is useful, the research team is also building a system with a Raspberry Pi microcontroller and high-resolution camera, which sends the images to a central computer for processing and interpretation.

Left: Dr. Krishna Nemali. Right: smartphone sensor  

Compared image-based monitoring to human evaluation
To test the efficacy of image-based crop monitoring, the research team grew lettuce and tomatoes under optimal and suboptimal conditions. In a blind trial, crop growth was visually evaluated daily by people (using a rating system) and by image-based sensors. As Dr. Nemali explains, the image-based system recorded statistically significant differences in crop growth between optimal and sub-optimal conditions 3-4 days before the human eye could detect differences.

“When you regularly take these photos and develop growth curves, you can monitor how your crop is measuring up against expected optimal growth. If these images indicate an issue, growers can resolve this before it is too late,” says Dr. Nemali.

The images can also be used to assess nitrogen status, germination percentage, and rate, and color progression, allowing the grower to monitor crop health, planting material, and estimate the time to harvest. Plant nitrogen status is usually measured in a laboratory, which is expensive and time-consuming or using expensive chlorophyll meters. Dr. Nemali’s research developed accurate algorithms using images captured by smartphones and microcontrollers to rapidly estimate plant nitrogen status.

Different plant measurements can be measured using images collected by a smartphone or microcontroller 

Instantaneously assessing plant nitrogen 
“Imaging the benefits of instantaneously assessing plant nitrogen status in CEA industry. Growers can supply fertilizers based on plant needs and avoid over or under application rates,” says Dr. Nemali   

As these technologies are being developed at Purdue University, they will be made available to growers at a low cost, with any generated funds being poured back into further research and development. The smartphone app should be available in the spring of 2022, with a low purchase price and yearly license.

With photo-quality varying according to the camera, ambient light conditions, and distance from the crop, normalization processes have been incorporated into algorithms to ensure high-quality analyses. To account for differences in distance from the crop between imaging sessions, each photo is taken with a standard, measured object in the frame.

“Let’s say we have a red square with a known area of 25 cm2 and we place it beside the crop in each image. The computer will recognize that object, uses its area to determine the right pixel-area conversion and apply it to the plant. This creates a relative scale and eliminates height/distance altogether,” says Dr. Nemali.

To normalize for different light conditions, the technology considers different reflected wavelengths, both of which are affected by light intensity. By taking the ratio of two wavelengths, the setup can eliminate the effects of light intensity on the images altogether.

A demonstration of smartphone-based image technology can be viewed on Dr. Nemali’s website at this link.

Additional areas of research
Aside from image-based crop monitoring, Dr. Nemali’s research group is conducting extensive research on nitrogen management in hydroponically grown organic lettuce production.

“The yields of organic lettuce is usually lower compared to conventional production, because of challenges with nitrogen availability to plants in organic production. While organic lettuce does command a higher price, we still need to increase these yields to make it sustainable and organic produce more available to consumers,” explains Dr. Nemali.

 Other areas of research include the use of ultraviolet radiation and ozone to reduce the risk of E. coli contamination in lettuce, and the optimization of production techniques to improve the nutritional density of leafy greens.  

For more information on ongoing research in Dr. Nemali’s research group:
Dr. Krishna Nemali
Assistant Professor in Controlled Environment Agriculture
Purdue University
https://www.purdue.edu/hla/sites/cea/ 

24 June 2021
Author: Rose Seguin
© HortiDaily.com

UAE, Israel Both Expect To Benefit From Agricultural Ties

TARA KAVALER

08/23/2020

Emiratis will have access to Jewish state’s agritech while Israelis will gain financially

The United Arab Emirates, where less than 1% of the earth is arable, is set to reap major growth from its agricultural sector with the help of Israeli technology after the two countries normalize relations.

Israel, a world leader in agriculture under conditions with little water and high heat, will sell its expertise to farmers in the desert nation where the average temperature in August is 43°C (109°F) and the average annual temperature is 30°C (86°F). Israeli growers also plan to export food to the UAE, from where it may be re-exported to currently unreachable markets.

The UAE and other Gulf Cooperation Council countries have been trying to become more self-reliant in food, most of which they import. The UAE has already seen an explosion in agricultural growth, particularly in vertical farming and other next-generation planting techniques. It plans to start using hydroponics, soil-less crop cultivation, before the end of this year. The regional government in the capital, Abu Dhabi, announced in April that it was investing approximately $100 million in vertical farming.

“Any food production here requires a technological solution,” Nicholas Lodge, a UAE-based agricultural expert, told The Media Line.

“It doesn’t make sense to grow almost anything in terms of arable crops, except for higher-value crops like tomatoes that are grown in greenhouses, with the latest technology, like hydroponics, where minimal water is needed,” Lodge said.

Dr. Yaron Drori, an Israeli agronomist and co-owner of Etza Agriculture consultants, told The Media Line: “There are very sophisticated greenhouses all over the world, especially in northern Europe, but what is special about Israeli equipment is that we know how to deal with the excess of heat in the structures.”

“Most of the year in our greenhouses, we are trying to avoid overheating. This is the opposite of what you are trying to do in Europe, where you are trying to gain heat,” added Drori, whose company specializes in desert farming in southern Israel.

The greenhouses in Israel use shade nets that can be turned on automatically with a “smart” control system that monitors temperature, radiation, and humidity.

The system also activates cooling sprinklers, or a “curtain” of water, which brings outside air into the greenhouse to change the high temperatures and low humidity that make desert agriculture difficult.

The device also irrigates plants without wasting scarce resources. Saving water is one of the centerpieces of Israel’s “advanced innovation” in agritech, Drori said.

Associate Prof. Zvi Peleg of the Hebrew University in Jerusalem spoke to The Media Line about his work at the university’s Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture to reduce the amount of water plants need.

“We are working now on how to improve water-use efficiency, meaning the plants will produce more biomass by using less water.”

“We are trying to change the plant … so it will be more suitable for the climate,” Peleg said. “We are changing the root system to become deeper … to get to the water more easily and reduce the size of the root architecture so it will not take so much water from the soil because it’s a very limited resource.”

He also explained some of Israel’s latest agricultural technology.

“By using sensors to check the water status in the soil and the plant, you improve productivity because you irrigate whenever the plants need water, not whenever you feel they need water,” Peleg said.

“We are also using thermal imaging to see if a plant needs water or nutrients. There are a lot of techniques now related to drones and different kinds of cameras to detect the plant’s growth, as well as diseases and other problems the plant has,” Peleg said. There is “a lot of technology that can benefit many regions, including the UAE.”

Meanwhile, the UAE is doing high tech agricultural research of its own. Dr. Mohammed Abdul Mushen Salem Alyafei, an associate professor at The College of Food and Agriculture at United Arab Emirates University, said studies are being done in the Emirates on an “open-top chamber,” which encircles a plant to examine the impact of carbon dioxide levels and an “aeroponic control unit.” Aeroponic devices grow plants in the air in a moist environment.

Israel’s successful efforts to make its own desert bloom have resulted in exports of its desert produce.

Some “60% of Israel’s [agricultural] exports, which include tomatoes and watermelon, come from the Arava [in the southeast], which is very similar to the UAE, with bad soil and poor [quality] and limited amounts of water,” Shafrir Godel, an agricultural business expert, told The Media Line.

“Everything is against the farmer, and yet it is the major export region for Israeli produce [sent] to Europe and America,” said Godel, founder and managing director of Israel-based AgriQuality, an international consulting company.

Long-distance exporting is very expensive, but Israel has figured how to do it profitably; this know-how could help the UAE.

“The chain from the seed to the supermarket shelf abroad is something that Israelis do well and cost-effectively: starting with the variety [of crop] to plant, the methods and technical solutions for growing, sorting, picking, the plastic you are using to extend shelf-life, and getting them to the right companies that have a hold on the main markets.”

Israeli growers are also looking for new markets.

“Over the years, Israeli farmers have grown with a capacity that is way beyond Israelis’ ability to eat. We need other markets. It is a new market, and it could be a transit station to places that we normally would not sell to,” Godel said.

The UAE is one of the world’s top three re-export hubs.

Agricultural expert Lodge noted that “the UAE has built a reputation as a transport hub serving many countries.” “It’s quite interesting what you might be able to do with that mix of location, technology, and capital for certain crops.”

Both countries’ agricultural businesspeople are excited about the potential for the new alliance.

“The UAE has a history of looking at where it can forge partnerships, where it can make investments where there’s a mutual benefit,” Lodge said. “Israel is an acknowledged leader in arid farming and the application of technology to make farming possible. I’m sure it’s one of the areas that could and should benefit both parties.”

Etza Agriculture’s Drori said: “If you bring the practical and academic knowledge and all the technology that we have to the UAE, we can all benefit from it, both the Emirati and the Israeli companies.”

“Israel gets business, so it benefits financially. But beyond that, it would be fascinating to work there. It’s a new place, you learn and see new things,” he said. “It’s a new world for us.”

Lead photo: Dr. Effi Tripler, a soil and water scientist, stands next to a solar-powered sensor that helps a drip-irrigation system know when and how much to water a crop of sorghum at the Central and Northern Arava R&D facility on May 21, 2015, in Hatzeva, Israel. The soil and water R&D facility tests and produces various crops in the dry, harsh climate of the Arava, near the Jordanian border. (Ann Hermes/The Christian Science Monitor via Getty Images)

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