Water is necessary for growing plants. This simple statement says it all, but doesn’t begin to address the complexities of water decisions growers face today. Some questions are common regardless of where your operation is located.

  • How much water do my plants need?
  • How does water quality affect plant growth?
  • How much water do I need to store?
  • How do I need to treat my water?
  • How can I be more efficient (waterwise)?
  • Should I recycle my water?

The answers to these questions differ by operation and location. There is no “one size fits all” approach to answering them — yet there are ideas and principles that we can take from one facility and adapt them for use at another facility.

Fresh water resources are valuable and finite across the U.S. Access to high quality water for irrigation is becoming more constrained, as urban and industrial demands for this limited resource are ever expanding. Since operational (business) security relies on consistent water availability, growers need to develop backup sources of water (for example, recycled water). Reluctance to use recycled water is motivated by concerns about the presence of plant diseases, pesticides, herbicides and salts in irrigation runoff. This reluctance has been reinforced by the lack of readily available information about whether (or not) these contaminants pose a problem and how we mitigate them in an economically feasible manner, when they are.

Image 1: Distribution of researchers, Extension specialists, advisory board members and growers collaborating on the Clean WateR³ project.

The need for answers to these questions led to formation of the Clean WateR³ (R³ = Reduce, Remediate, Recycle) Team. In September 2014, a team of 21 researchers from nine institutions, 11 collaborating growers, and nine advisory board members were awarded a grant from the National Institute of Food and Agriculture, United States Department of Agriculture, Specialty Crop Research Initiative, to work on the project (# 2014-51181-22372). As of June 2017 (three years in), the Clean WateR3 team includes 30 team members, consisting of university professors, undergraduate and graduate students, research technicians, and post-doctoral research associates, all working to accomplish the project goals of helping growers treat and reuse operation water to both save valuable water resources and to reduce the potential environmental impacts of contaminants in irrigation runoff. Team expertise includes economists, sociologists, environmental toxicologists, ecological engineers, horticulturists and plant pathologists.

Clean WateR³ Components:

The goal of the Clean WateR³ project is to encourage recycling and reuse of remediated irrigation runoff by:

  • developing and publishing online decision support tools to aid growers with identification and implementation of innovative technologies to recycle water for reuse or release;
  • reducing contaminant loading into recycled water sources by (a) installing treatment technologies and (b) managing production inputs to reduce pathogen and agrichemical presence;
  • identifying and developing biological and physical treatment technologies, which (a) effectively remediate plant disease, pesticide and nutrient contaminants and (b) integrate the treatment technologies into existing operations with minimal impacts on labor, costs, production area and energetic or chemical inputs; and
  • communicating project outputs to growers to encourage adoption of defined practices to reduce, remediate and recycle production runoff.

Online tools

Want help determining how much water you need over a month (year), how much risk from disease is posed from recycled water at your operation, or how much stormwater will be generated during a 1-inch storm-event? We’ll have the tools for you — online — where you can enter operation-specific data to customize results, helping you find the information you need to make informed decisions.

The Clean Water Modeling team is in the development phase of multiple tools (including a water budget, chlorination, stormwater and disease risk assessment) and have developed and validated a model that simulates water movement in a soilless substrate. These tools will be connected, so if you enter information for one it will be linked to others so that you don’t have to enter the same information at multiple points.

Image 2. Reducing contaminant loads leaving production areas can enhance efficacy of treatment technologies and ultimately use of recycled water.

The great thing about a model is that you can change any of the inputs, and quickly see what impact it might have.

Want to know how much carbon dioxide (CO2) a given crop takes to produce? Or find out which production practice contributes the most CO2 to each plant produced? We have developed carbon footprint evaluations for evergreen shrubs in both the eastern U.S. and western U.S. Water footprint analyses for eastern and western U.S. nursery operations are currently being validated; this will help you determine which points of your production chain use the most water to produce a crop — and help you choose what to change to have the most impact on saving water.

With the help of 11 growers across the country, both small-scale and pilot-scale treatment technologies (best management practices) are being evaluated to determine their effectiveness at removing agrichemicals and plant diseases from irrigation runoff. Information related to the efficacy of treatment technologies will inform and validate models being developed as part of the project. We will be able to help you predict (within a certain set of constraints) how effectively a treatment technology will remove plant diseases, pesticides or nutrients from recycled water. These models will also contain information on average cost and return on investment, and contain “if-then” web-based scenarios to help you make informed decisions regarding your water management.

Image 4. Full scale (rapid paper filter, top) and laboratory scale (granular activated charcoal, bottom) and pilot scale installations of treatment technologies designed to manage suspended sediment and agrichemicals.

Reduce and remediate

Reducing contaminant loads

Being able to account for production system-wide impacts of cultural practices and technologies (for example, automated irrigation scheduling, deficit irrigation, fertilizer placement, substrate engineering) is an ongoing area of research. By being able to better understand nutrient leaching, pesticide fate, plant disease incidence, survival and loading in irrigation runoff, we can work toward saving money and time, and reducing environmental impacts. If we can quantify non-traditional costs associated with less-than-optimal water use, we can begin to gain an understanding of the true cost of current water use practices.

How does water use affect nutrient losses, incidences of plant disease and survival, plant growth, reductions in fungicide use and other (labor, energy) costs? Growers have identified economic and environmental factors as influencers of decision making. Thus, by characterizing both the economic costs and benefits of a changed practice (reducing input costs or minimized leaching of fertilizers) along with the environmental benefits (less offsite contamination), we provide information designed to help growers make informed decisions. For example, we have documented water saving per block of chrysanthemum (8 and 13 inch) and poinsettia ranging from 2 to 10.2 percent (36 to 2,800 gallons) when irrigation decisions were made using soil moisture sensors versus timed irrigation. Water savings alone often are not adequate to entice growers to alter irrigation practices; however, increased crop quality, faster turns and reduced energy (pumping), fertilizer and fungicide costs are factors that will likely drive changes in practice.

Treatment technologies

Which treatment technologies will help mitigate plant diseases? Which will help remove pesticides? Which will help limit nutrient release offsite? Many technologies have been assessed for other applications (think row crop agriculture, construction sites and wastewater treatment), but their effectiveness in cleaning irrigation runoff from specialty crop production operations has not been evaluated. Thus, we are assessing both physical and biological treatment technologies and quantifying contaminant removal efficacy. Some of the technologies we are evaluating are discussed below.

Pretreatment of water via rapid filtration is critical for chemical and physical treatment technologies. Removing suspended solids can reduce demand for sanitizing agents (such as chlorine), increase the efficacy of sanitizing treatments (for example, ultraviolet light transmission) and remove particles that harbor plant pathogens. We are currently evaluating the effectiveness of rapid physical filters at removing suspended particles at multiple grower facilities. Granular activated charcoal (carbon) filters are being evaluated for their efficacy in removing pesticide residues with collaborating partners.

Floating treatment wetlands (FTWs) are a well-researched technology for nutrient remediation in stormwater. No research has been conducted evaluating plant disease removal by FTWs or the potential for scaling up this technology for commercial production scenarios in which cost of implementation and life of the technology are evaluated. The efficacy of FTWs to remove nutrients and plant diseases continues, including an economic component of FTW installation and maintenance.

Filter socks are a proven best management practice for managing runoff from construction sites. Filter socks are low-cost and require little to no change in existing infrastructure to mitigate sediment. Sediments act as a carrier for both phosphorus and pesticides. Measurement of the efficacy of filter socks to remove total suspended solids, phosphorus and nitrogen continues both at research facilities and with collaborating growers.

Image 3. Mums grown using irrigation controlled by soil-moisture sensors.

Socio-economic assessments

Adoption of reduction, remediation and recycling practices by growers requires economic information related to the cost and benefits of practices; we are modeling the cost of both standard water management practices and recommended changes in practice. These economic data will serve as a baseline, helping to document the socio-economic impacts of strategies that reduce post-production shrinkage and quality related to mismanagement of water. Financial motivation can drive rapid changes within an industry, thus understanding obstacles or motivators to adoption or application of recommendations will ultimately affect changes in practice.

Presenting this information in a way that is useful to growers is key to motivating change in practice. We consulted with growers both in person and via a national survey and are using these results to guide how we present information in workshops, webinars and the project website (http://cleanwater3.org).

Image 5. Laboratory and pilot scale installations of floating treatment wetlands (left) and filter socks (right) designed to manage suspended sediments, nutrients, agrichemicals and plant diseases.


Outreach and communication of research results to stakeholders are critical components to project success. A series of six water conservation webinars were presented by the Clean WateR³ team in January and February 2017; see the webinars. We also release a regular newsletter promoting new research outputs; you can sign up for it.

If you are looking for in-person information on the project in July you have 2 opportunities:

  • You can still register for the full-day water workshop at the California Nursery Conference with presentations by team members from California, Florida, Kentucky, Maryland, Michigan, South Carolina and Virginia.
  • You can attend Cultivate in Ohio and see presentations on cost analysis and water recycling.

The Clean WateR³ team values your input and feedback on this project. Our goal is to serve the needs of the industry, so please don’t hesitate to contact us with questions.

Literature cited

  • Fisher, P.R., Mohammad-Pour, G., Haskell, D.W., Huang, J., and Meador D.P. 2013. Water sanitizing agents such as chlorine and chlorine dioxide interact with peat substrate and suspended solids. Acta Horticulturae. 1013, 279-284.
  • Ingram, D. L., Hall, C. R., and Knight, J. 2016. Carbon footprint and variable costs of production components for a container-grown evergreen shrub Using Life Cycle Assessment: An East Coast US Model. HortScience, 51, 989-994.
  • Saavoss, M., Majsztrik, J., Belayneh, B., Lea-Cox, J., and Lichtenberg, E. 2016. Yield, quality and profitability of sensor-controlled irrigation: a case study of snapdragon (Antirrhinum majus L.) production. 34, 409- 420. doi:10.1007/s00271-016-0511-y
  • Wang, C.Y. and Sample, D.J. 2014. Assessment of the nutrient removal effectiveness of floating treatment wetlands applied to urban retention ponds. Journal of Environmental Management. 137, 23-35.
  • White, S.A. and Cousins, M.M. 2013. Floating treatment wetland aided remediation of nitrogen and phosphorus from simulated stormwater runoff. Ecological. Engineering. 61, 207-215.