Ahead of the curve

Jim Marshall, general manager at Suncrest Nurseries near Watsonville, Calif., had the foresight to implement a water conservation program at the nursery years before state mandates and the grip of the current (and prolonged) drought took hold.

“It was just common sense that we didn’t want our water to go down the drain and not use it as efficiently as possible,” Marshall says. “It was also very obvious that we would someday be facing a water crisis because there is so much development, and we are all sucking from the same straw. By doing this, we are making every effort to help our future. The company has been in business as a nursery since 1878, and there is a lot of legacy that I would like to sustain.”

Suncrest Nurseries is a wholesale operation that grows and sells more than 3,000 varieties of plants, primarily in 1- and 5-gallon pots on 60 acres.

“We’re one of the most diverse nurseries in the state,” he says. “And at our core are California native plants.”

In 1989, a group of investors purchased the historical Leonard Coates Nurseries, which was one of the first nurseries to promote California native plants.

Marshall, with a background in hydrology and a history of working with the original nursery, made water his highest priority for the redevelopment of the property. He designed a water recovery and computer-operated irrigation system that cut the nursery’s water use in half.
 

The setup

The water recovery and recycling system captures nursery runoff and blends the nutrient-rich water with fresh water for reuse as nursery irrigation water. An impermeable Visqueen 6-mm thick, polyethylene barrier lines the entire nursery and eliminate percolation losses and sediment erosion. Each nursery block is gravity profiled to direct the flow of surface runoff, and rainwater from the downspouts on all buildings. A network of drains and underground trenches transport runoff to recovery ponds at the low end of the nursery blocks. Don’t skimp on a filtration system.

“It’s a good idea to have a very high capacity, self-cleaning filter,” Marshall says. “The filter is important because the pond is exposed to sunlight and runoff fertilizer. Algae quickly grow in the water and plugs up sprinklers and drip emitters.”

The recovered water is cleaned with chlorine dioxide as a precautionary measure for pathogen control, Marshall says. After blending the recovered runoff with 50 percent fresh water, Suncrest recycles the water back through the irrigation system.

“The biggest concept that most people don’t appreciate is gravity,” he says. “Water flows downhill and that is the simplest thing. All you have to think is where am I going to collect it? You want to design it at the lowest part so that gravity does the work for you.”
 

In the zone

The nursery irrigates based on plant needs by means of a computer-operated irrigation delivery system that precisely controls irrigation scheduling and timing.

“We have very precise control over the amount of time that we water,” Marshall says. “We are pumping approximately 1,800 gallons a minute, and the consequence of being much more precise in our delivery time is that we are conserving water.”

The nursery also is organized in irrigation zones based on plant water needs to maximize water distribution uniformity. Most of the plants in 5- and 15-gallon containers are on drip irrigation. The 1-gallon pots are irrigated with sprinklers. Recently, the nursery completed a study using wobbler sprinklers compared with impact sprinklers.

“We’re going to modify portions of the nursery to improve the coverage and get the coefficient of uniformity increased,” Marshall says. “We’re shooting for a coefficient of uniformity in the mid-80s from our current coefficient of the high 60s. That’s in response to the drought. Since the drought, the California government asked all of agriculture to reduce water use by 20 percent.”
 

System benefits

The nursery has reduced its reliance on groundwater. And increasing input efficiency has allowed Suncrest to expand the business. But Suncrest’s recovery and recycling system has added benefits. The system provides greater control over nutrient management because it is a closed system, he says. It promotes healthier plant growth and reduces inputs by capturing excess water used to leach salts that build up from fertilizer, and by recycling the nutrients back through the system.

Profiling land to maximize gravity flow for the drainage system also reduces electricity costs. Additionally, pumping water from the storage ponds requires less energy than pumping water from the ground.

Sources: California Institute for Rural Studies (www.cirsinc.org) and Jim Marshall, Suncrest Nurseries (www.suncrestnurseries.com).