Water is one of the most important resources on a dairy farm, not only because it is essential for cow consumption, but also because it is heavily used to wash, clean and cool the dairy facility.
In some regions, it is a limited resource, while in other areas water use must be stringently managed because of the volume it adds to manure storage and application plans. In either scenario, producers can benefit from on-farm water conservation without sacrificing cow comfort, and sprinkler systems are a good place to start.
The following are five opportunities producers can apply to their sprinkler systems to reduce water wastage:
1. Check valves
Check valves prevent backflow of water in a pipeline and are effective at stopping water from draining from the sprinkler system when it is turned off. If the sprinkler nozzles do not have mechanical check valves internally, they can be installed to save the volume of water in the pipeline, says Michael Evans, marketing supervisor for Edstrom Industries.
“Every time the sprinkler system shuts off, you don’t want the overhead pipeline draining out,” Evans explains. “Since you are using at least an inch or inch-and-a-half pipeline, it causes a lot of water in the overhead pipeline to drain out each time.”
Evans says when the water is turned off, the pressure in the pipeline suddenly drops from 40 psi to almost 0 psi. Without a check valve, the water would drain out. However, with a check valve, the pipeline is closed off so the water can’t drain out until it increases above a pressure of 6 to 8 psi.
“I am thinking probably on the high end, 10 gallons per cycle is wasted,” Evans says. “So when you are talking say four cycles per hour, it can waste 40 gallons per hour.”
2. Nozzle size
The nozzle size of a sprinkler controls how much water is delivered and the water droplet size. Evans recommends selecting a nozzle that creates rain-drop-size droplets and less mist. He says the larger droplets will reduce spray drift and penetrate the cow’s hide.
“You don’t want to see a mist floating around or a fog that will float in the air and get blown around,” Evans says. “If you have a cross breeze, it would blow the water out of the building and into areas that don’t need it. That right there can contribute to a lot of water wastage.”
The use of a coarser droplet also penetrates the hair coat of cows for direct evaporative cooling from the cow’s skin instead of running off the body.
“The other reason we don’t want to have a fog or a mist is that it actually detracts from the cooling of the cow,” Evans says. “If you get just a mist on her hair coat, it actually becomes an insulative blanket, and she is unable to get rid of her body heat, and makes the cow hotter instead of cooler.”
3. Spray radius
The two main types of sprinkler radiuses installed are 180-degree nozzles next to feedbunks that throw water toward freestalls and 360-degree nozzles in the center of the cow alley or holding pen. Depending on the nozzle spray pattern and water pressure, it is important to space sprinklers as far apart as the radius of the throw of each sprinkler to avoid overlapping coverage.
“Normally you want to try covering the diameter or the width and length of the pen and no more,” Evans explains. “Select the nozzle diameter to fit the pen size you are working with to not get excess spray in areas you don’t want to wet or spraying outside the walls of the holding pen either.”
Evans says the amount of water a producer can save by having the correct spray radius is relative to how much is overlapping or spraying outside the pen.
4. Timer
To avoid leaving a sprinkler system on consistently, a 15-minute, adjustable timer can be installed to control the sprinkler cycle. Jennifer Chen, a postdoctoral scholar in the department of animal science at the University of California – Davis, says having a timer linked to the sprinkler system allows a producer to know he is using the same amount of water each time.
“It is important to have a timer to remove human error because often the workers are really busy, and if it is somebody’s job to turn on and off the water, then sometimes it can get overlooked by accident,” Chen says.
If sprinklers are located beside or above fans, the timer can also be used to shut off the fans while the sprinklers are running so the two are running in sequence and not together, thus saving additional water.
Chen says farmers can even connect additional layers of timers to turn the sprinklers on and off when they know the cows will be away for milking.
5. Thermostat
Thermostats should be installed to control both sprinklers and fans. Michael Brouk, a Kansas State University dairy extension specialist, says a lot of dairies operate fans at 60 degrees and their sprinklers at 70 to 75 degrees.
“A thermostat normally is built into the system controller, so you can set a low temperature and a high temperature and then set the interval to how often the sprinklers are going to run a cycle,” Brouk says. “Low might be once every 15 minutes, and the high temperature might be once every five minutes. It then creates a line between those linear points and gradually increases the amount of water it uses based on temperature.”
Brouk says a thermostat allows a producer to reduce the amount of water he or she uses at a lower temperature and increase the amount of water used at a higher temperature when cows need more relief.
“If you set up your system without the thermostat and you just soak cows once every 15 minutes, you don’t save water in that situation and you also don’t do a very good job of cooling the cows,” Brouk says. PD
Audrey Schmitz is a 2016 Progressive Dairyman editorial intern.
PHOTO: Sprinkler systems can offer a relief from heat stress for the cows, but they must be managed and maintained properly to provide effective cooling and wise use of water resources. Photo by Peggy Coffeen.
