Automated irrigation pump control protects a Florida nursery's crops.
by Dan Vnuk, FW Murphy

Central Florida has a climate that is perfect for growing just about anything. Despite its abundant resources and mild winters, a killer frost can quickly wipe out an entire crop. A smart and efficient water-use strategy can provide a protective layer of warmth, acting as one of the weapons in a grower’s frost-fighting arsenal. However, the equipment has to be available when needed, even if the local power grid is down.

Pump and motor controllers manage irrigation at a large Florida nursery.

Windmill Farms Nurseries, Inc., is a second-generation agricultural enterprise located near Sebring, Fla. Started 40 years ago as a row crop and cattle operation, it moved to farming citrus groves. During the past 15 years, it has grown into a year-round plant nursery.

Windmill grows more than 150 varieties of containerized perennial ornamental/landscape plants and ground cover. The nursery annually produces about 5 million plants—in 1 and 3 gallon pots—on 75 acres. Three crops per year are produced and shipped through its own fleet of refrigerated semitrailers to customers throughout Florida and the eastern U.S. Windmill has experienced 300 percent growth during the past six years and expects further growth in 2012. Windmill Farms is owned by brothers, Jason and Eric Cord.

Computerized Water Supply System

Windmill Farms Nurseries Inc., recently completed a $300,000 irrigation project with South Florida Water Management District.  Development for the project included the construction of a recovery pond to capture water runoff and the installation of a computerized system to monitor the recovered water in each zone.

“The installation of the new water-management system was actually a five-year process,” says Jason Cord, Windmill vice president. “Like a lot of other businesses, nurseries have turned to automation to smooth production and continue growth.”

During that process, Windmill chose a monitoring system for the two pumps at the retention pond. These pumps, one driven by an electric motor and the other by a diesel motor, are responsible for moving water from the pond for irrigation. For Jason Cord, the chosen system was the best fit for the project and the climate.

“It can use variables such as sunlight and temperature to control water flow and pressure,” he says. “It is critical during the colder months when frost is a concern.”

The system will play an important role in the overall water usage throughout a crop’s life cycle. However, the climate protection that an automated system like this offers was the deciding factor.

“While the automated system will eventually monitor usage from propagation through the growth cycle, perhaps its biggest asset is protection from freezing,” Jason Cord says. “If I lose a crop to frost, my whole spring is shot. If the pumps go down when it is 28 or 30 degrees, I’ll lose a lot of material for shipping. We’ve had cold snaps as early as November, but being able to pump water to protect the crop in January and February is most critical.”

Before the half-acre retention pond was dug, the nursery used wells to tap groundwater for the individual plots. “We would have 5 acres here and 7 acres there, each with its own well that had to be monitored, which meant that I would have to be here many hours a day, 7 days a week,” he says. “We would constantly have to adjust the amount of water needed as the temperature changed or when the sun came up and went down.”

Normally, the electric motor pump supplies all the usual life-cycle needs of the nursery. However, the diesel unit is also brought online for extreme demand periods. The control system is set to start the diesel-engine unit whenever the temperature drops to 36 F, ramping up all the pumps to 30 psi. The water will ice-in the plants, keeping a layer of warmth from a pocket of air that forms between the leaf and the ice surrounding it.

Diesel Pump Relies on a Separate Controller

The electric pump has a variable speed drive that enables it to deliver from 5 to 320 gallons per minute. The diesel unit, which can pump up to 4,000 gallons per minute, also functions as a variable speed drive and can hold the pressure at design point because of a separate controller. Besides pump speed, the controller manages engine start/stop and rpm. It also monitors the unit’s overall performance. Hardwire links the controller to the control office, but wireless monitoring is available through cell, satellite and RF devices.  

“It’s an economical alternative to standard engine/pump control devices yet it brings a level of automation that’s working out well for us,” Cord says.

When it comes to the controller’s advantages, Cord focuses on the increased efficiency for his operation and his workload. “The Murphy EMS PRO makes efficient irrigation easier and reduces the chance for human error, which can have drastic consequences,” he says. “There’s also a labor factor. I don’t have to send someone out to make sure the engine is running. The speed of the pump and engine RPM are in synch, therefore everything connected with the engine is running properly. 

The psychological benefits may be worth as much as the improved output. “Every day I get more comfortable with it. There’s definitely a ‘peace-of-mind’ factor as well in that, with the EMS PRO, there’s a lot less to worry about,” Cord says.