Reduce, reuse, remediate: Helping nurseries get the most out of their water

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Container plants in a nursery. (view larger image)

From flowers to Christmas trees, nursery plants are big business for Michigan — they’re the basis for a $1.2 billion industry that accounts for more than 36,000 jobs.* Maintaining enough plants to meet consumer demand requires a lot of water, and providing water carries costs to both the environment and the grower.

Many nurseries grow plants in containers — pots or baskets that restrict thesprawl of roots and allow plants to be efficiently stocked and sold. An unintended consequence of this approach, however, is that such plants need more water and fertilizing nutrients to keep them healthy than those grown in the ground.

The inputs also increase the potential for pollution in the form of runoff. Excess water can wash out of the nursery and into lakes, rivers or groundwater, carrying the phosphorus- and nitrogen-rich fertilizer with it. Such runoff has been the basis of significant environmental hazards in recent years, most notably the toxic algal blooms in Lake Erie near Toledo in 2014.

A team of researchers from Michigan State University (MSU) AgBioResearch is working to address both the environmental and financial concerns by developing a system to purify and recycle water and fertilizers.

“One of the main challenges that container nurseries face is that they use a lot of inputs that are concentrated in a small area, which is an almost ideal scenario for runoff,” said Tom Fernandez, associate professor in the MSU Department of Horticulture. “What we want to do is look for ways that theycan reduce the application of those inputs, remediate the water so that it isn’t carrying anything that could be environmentally hazardous and ultimately recycle it back through the nursery.”

Fernandez and fellow MSU AgBioResearch scientists Bert Cregg and Bridget Behe are part of Clean WateR3, a multiinstitutional research partnership founded in 2008 through a U.S. Department of Agriculture Specialty Crops Research Initiative grant to help greenhouse and nursery growers use water efficiently and sustainably. By combining technological, pathological and marketing expertise, the team is working to create a system that benefits growers, consumers and the environment.

Fernandez and his students are conducting experiments on nursery beds to determine the efficiency and impact of various irrigation techniques. The beds are designed so that runoff water can be captured on the surface and approximately 1 foot below. The volumes of pesticide and fertilizer are then assessed. The team will compare the chemical and physical impact of 10 common nursery pesticides, and determine the minimal level of necessary irrigation.

Reducing the volume of inputs is important, but remediating those already present is of equal significance. Fernandez is testing several subsurface bioreactor systems — layers of organic material such as woodchips or bark — deposited beneath the growing surface to naturally cleanse runoff water of chemical impurities.

“When you look at pesticides and fertilizers, they’re all made of organic compounds,” Fernandez said. “All of those elements are used by microorganisms as food sources, so if we run the water containing those compounds through their habitat, they’ll break down and metabolize them into a nontoxic form.”

Cregg is studying the impact of the technologies on nursery plant health and growth.

“We’re approaching this from a fairly basic plant health perspective,” said Cregg, associate professor in the MSU Department of Horticulture. “Our main concern is the impact that recycled water could have on plant growth and whether the fertilizer or pesticide chemicals it might bring will have a negative impact on them.”

While Fernandez’s team collects runoff, Cregg will study the impact of that water on the plants grown in the nursery beds, comparing the water treated through remediation techniques to that of untreated water.

“We’re looking for changes in large-scale plant characteristics such as growth, coloration and rates of photosynthesis,” Cregg said. “The best case is that we don’t find anything — that’s good news for growers. On the other hand, if we find a problem now, that means we can work to adapt the technology to address that problem now so that growers don’t have to.”

Behe is studying how consumers incorporate information about the water usage and sustainability of greenhouse and nursery products into their purchasing decisions.

“My whole research program has been positioned to provide information on the consumer to small, medium and large growers,” said Behe, MSU professor of horticultural marketing. “Everyone in the channel of distribution benefits from an understanding of consumer behavior.”

Behe uses eye-tracking technology, which employs infrared light to follow the motion of a subject’s pupils, to determine which parts of a product display consumers look at most.

“Our eye movement is deliberate and taskspecific,” Behe said. “You look at things differently depending on whether you are driving a car, looking at a work of art or deciding what type of plant to buy. With the eye tracker, we can see who is looking at a piece of information and how they are looking at it, and relate that to whether they decide to make a purchase.”

By studying how consumers read plant displays that highlight water use information, Behe can begin to understand how important it is to the economic success of nurseries and greenhouses. This is important to many states, especially where water use is tightly regulated.

“Most nurseries today are not wasteful,” Behe said. “We’re trying to understand how to help them tell that story to their customers in more effective ways.”

Improving the capacity for recycling and remediating water has numerous potential benefits.

“It’s been very satisfying in the past few years to see that we can substantially reduce the amount of water and nutrients that move off-site, and now — through this project — we have the chance to improve on that further,” Fernandez said.

* Michigan Nursery and Landscape Association

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