Drivers passing by the 200-acre Nickels Soil Lab research farm in Arbuckle, Calif., might wonder if Big Brother is watching as a small drone helicopter with a camera sometimes flies above the tree line in the experimental almond and walnut orchards.

Big Brother is not at work. Instead, precision agriculture specialists are developing the latest technology to find future solutions for crop water-challenged growers in Western U.S. agriculture.

The drone copter, manufactured by MiKroKopter, measures canopy reflectance in the tree nut orchards as part of a three-year, Western state precision agriculture project called, “Precision Canopy and Water Management Study in Specialty Crops Using Sensor-Based Decision Making.”

At the project’s core is discovering solutions for ever tightening and costly water supplies in the West and how cutting-edge technologies can help specialty crop growers produce more crop with less water.

Shrini Upadhyaya is the project leader and a machinery systems engineering professor at the University of California, Davis (UC Davis) in Davis.

The project addresses a very challenging task, Upadhyaya says. In the next 10 years, the challenge is to produce 21 percent more food with about 17 percent less water, according to some experts.

The challenge is part of the overall need to feed a burgeoning global population expected to jump from about 7 billion people today to more than 9 billion people by 2050.  

The three-year precision agriculture project is funded through a $2.59 million USDA specialty crops grant. It draws the expertise of precision technology specialists in five western states. Five universities are involved, including UC Davis, the University of Arizona, New Mexico State University, Oregon State University, and Washington State University.

Researchers from these institutions - plus Trimble, Veris Technologies, AgInformatics, and other commercial businesses - are among the 24 project investigators, plus support researchers.

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The project, soon to enter its third year, is designed to improve canopy and water management in almonds, walnuts, pecans, and grapes, plus other specialty crops in the future. The emphasis involves the latest developments in precision agriculture technology.

“The long-term goal of this project is to establish the basis for precise management of specialty crops at levels currently unattainable with satellite-based and aerial sensing,” Upadhyaya says.

In the area of water management, the objective is to determine precisely how much water plants truly need and then implement a targeted irrigation regime to deliver exact amounts of water while also boosting yields.  

Jury still out

Achieving this goal involves gathering plant and soil water status information through GPS, a lightbar system, drone copter, sensors, and other tools.

Collected information is sent to one or more computers through data acquisition systems for data tabulation. The information would help producers precisely determine when and how much to irrigate.

UC Davis Extension Specialist Bruce Lampinen assists the research team in canopy tests to determine whether a lightbar mounted on a retrofitted Kawasaki Mule four wheeler travelling across the orchard floor can effectively and efficiently measure photosynthetically active radiation or PAR – the sunlight absorbed by the leaf.

Absorbed light energy, through a process called carbon dioxide assimilation, produces a crop.

Lampinen had demonstrated that this information can help predict potential yield and assist in managing crop canopy. Upadhyaya and his students are exploring the use of PAR absorption data in irrigation and potentially in nutrient management.

The other question is whether a drone copter outfitted with multispectral and thermal cameras can more accurately and efficiently gather the data.

The jury is still out on the answer.

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Inside Bainer Hall at UC Davis, associate development engineer Jedediah Roach overseas the data collection and analysis performed by the drone copter. With a video game-type controller, Roach operates the experimental craft in the Nickel’s field tests.

“With the lightbar and the copter, we are able to look at trees from below and above,” said Roach. “We will proceed with whichever method is more efficient and cost effective in the end for the producer.”

Whichever system works best, it could help the producer make more accurate irrigation decisions to save water and nutrients while improving agriculture’s environmental footprint.

Another part of the study involves the use electronic sensors and controllers attached to a solar-powered wireless network mounted on posts in the orchard which can monitor soil and plant water status. The node can also operate latching solenoid irrigation valves.

The third-generation sensor suite, which can monitor plant water status by observing canopy temperature, wind speed, relative humidity, and PAR, is under development to recommend when and how much to irrigate.

Preliminary tests suggest that one node per one-third acre (50 trees) could be economically feasible with a yield increase of about 15 percent. One node per acre (150 trees) could be feasible with a 5 percent yield increase at the costs of current advanced technologies.

Information is fed into a computer, such as the universal navigation computer developed by Trimble. Trimble’s system includes a touch-based 12.1-inch-color monitor inside rugged housing, along with an improved GPS for use in heavy canopies, an interface to configure data logging, and a method to extract the GPS-tagged data.

From there, a visualization and decision support system would process the data into meaningful 2-D or 3-D maps. A variable rate water application system, including a network of UC Davis-built sensors and controllers, would include variable rate irrigation strategies for the grower to consider.

Specialty crop benefits

“As water resources become more scarce, this system would allow the farmer to make the final decision on when and where to precisely irrigate,” Upadhyaya said.

The project includes economic analysis assistance to help the grower decide if the system is affordable. Ag Tools, a web-based tool developed at Oregon State University, helps producers to make short-, medium-, and long-term decisions on system affordability.

As the research project nears completion, the program will be closely evaluated through a survey of industry stakeholders - including growers, commodity groups, Extension specialists, researchers, and others – to determine if it is commercially viable or needs refinement.

The project will enter its final year this fall. Upadhyaya will request a fourth year of work using current grant funds to make the final project decisions and complete scheduled Extension activities.

Project investigator Michael Delwiche of UC Davis says the system offers many benefits for specialty crop growers.

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“The system offers producers a more efficient way to manage water,” Delwiche said, “As water becomes more expensive, it will allow producers to manage water more efficiently to get more crop per unit of water.”

Delwiche says the technology could also open the door for more fertigation improvements which could reduce runoff and groundwater contamination.

In wine grapes, the system could help growers maximize profitability through improved grape quality.

“The ability to more precisely control irrigation in wine grape vineyards might allow the grape grower to gain more uniform crop maturation which could increase profitability,” Delwiche said.

Upadhyaya says the first portion of the precision agriculture system - variable rate irrigation management - is currently available from Camalie Networks. The final components, detecting plant water status in real time to assist in irrigation management, could be available within five years.

 “The technology to efficiently and effectively deliver water is here,” Upadhyaya concluded. “We have to use water wisely. Plant water management is the key. We are making good progress toward that goal.”

The USDA specialty crops funding grant is under the contract SCRI–USDA-NIFA No. 2010-01213.

For more information, contact Upadhyaya at [email protected].

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