One way to use water more efficiently is to use it twice. That’s the idea behind a Professional Development Project grant in Utah to promote water recycling in the state’s nursery industry.
“I came here from Michigan and it’s a common practice to recycle water in nurseries there and on the eastern seaboard,” explained Utah State University Assistant Professor Shital Poudyal, who is in the Plants, Soils and Climate Department. “Many nurseries have retention ponds and then they recycle their water and use it to irrigate again, both to benefit the environment because the runoff from a nursery has a lot of agrochemicals, and to reduce overall water usage.”
In Utah the practice hasn’t been widely adopted, in part because runoff helps maintain the Great Salt Lake, which before last winter had been shrinking alarmingly due to the years-long drought.
“While we want water to flow into the Great Salt Lake, we want clean water going into the lake,” Poudyal said. “Nearly 50% of waterways in Utah are impaired or contaminated and retaining water laden with agrochemicals can reduce that impact.”
The basic concept is pretty straight forward.
“Take a basic container nursery production,” Poudyal explained. “Usually it’s outside and the plants are irrigated. So the idea with water recycling is to slope the land and have a big retention pond that's lined with some impermeable substance so you can capture the irrigation water there to reuse it. In this project we’re trying to do demonstration projects of this model with Progressive Plants Nursery near Salt Lake City and a big tree nursery in southern Utah.”
While the general engineering of capturing irrigation runoff isn’t complex, there are several factors to plan for before the water can be safely reused. If high concentrations of pesticides are present in the captured water, they may have to be diluted or otherwise remediated before the water can go back on plants.
“If the water needs treatment, we can build a simple bioreactor containing something that absorbs or adheres to those pesticides and promote microbial action. Microbes feed on pesticide and degrade them. Something as basic as wood chips can be a bioreactor material,” Poudyal said. “We send the water through bioreactors at different flow rates so the pesticides degrade and then the water goes to a clean pond or in the case of nursery, they would just reuse it back on the plants.”
Plant diseases like Phytophthora are an even bigger concern when reusing nursery irrigation water, and it’s one of the areas Poudyal’s project addresses. Aimed at an audience of professionals in the nursery, water conservation, state government and extension arenas, the project will organize a series of workshops presented by topic-area experts. The idea is that at the end of the two-year effort, Poudyal’s project will have trained a number of professionals who can train and assist individual nurseries in implementing future water recycling programs .
“We’ll have a disease expert and water recycling expert talk about how we can sample the retention pond for diseases and the best ways for a nursery or landscaper to reduce the impact of diseases from recycling water,” Poudyal said. “We already had Dr. Sarah White talk about the viability of water recycling system for nursery industry. Important questions remain – what needs to be done? Does it even work? What does it cost and when can you get a payback? We had Dr. Robin G. Brumfield and Dr. Raul Cabrera speak on the economics of building a water recycling system.”
Future workshops – all of which will be recorded and posted to YouTube – include monitoring and mitigating agrochemicals, monitoring and treating diseases, Utah-specific rules and regulations, using smart sensors and controllers to automate irrigation, and even a session on marketing to explore if recycling water can be a selling point for nurseries.
“The idea is for all the stakeholders involved in water conservation to have this knowledge so they can take it and give it back to their community,” Poudyal said. “And then we believe that the impact from this project would multiply rapidly.”