When making decisions, whether complex or simple, you commonly pause to ponder what you are currently doing, what you’ve tried in the past, and then contemplate what you will do based on those experiences and the relevant information on-hand. Oftentimes, this approach helps you critically arrive at a solution that may not have been obvious at first, but upon reflection builds upon experience, current practice and future needs.
Past: Grower perceptions of water issues and practices
When developing research priorities and strategies to help nursery growers manage water, the Clean WateR3 team took this approach (see “Securing Water Resources” in the July 2017 issue for more information our research to Reduce, Remediate and Recycle water used for specialty crop production). We met with and surveyed individuals and groups of growers across the U.S. in 2011, documenting their current practices and listening intently to capture their greatest needs and challenges as related to water for growing plants.
Information from the survey and discussion groups grounded the goals for the Clean WateR3 project that researchers are working to meet now, so that in the future, growers acquire, retain and efficiently manage water to maximize profit and comply with environmental policy.
Baseline information related to current production practices (irrigation, fertilization and best management practices) were collected from 152 growers producing ornamental crops in greenhouses (40 percent), container nurseries (35 percent) and field operations (25 percent).
Well water was the primary source of water for most operations (65 percent), followed by collected rainfall or a retention pond (43 percent) and surface water (25 percent). Most operations have adequate water for day-to-day irrigation (86 percent). Daily pumping capacity for some operations limits water availability at peak irrigation times, so some operations must store water to meet irrigation demands (see Image 1).
But if we take a closer look at water availability, we see that 50 percent of operations were not always able to apply water as needed due to limited capacity on hot days or during a drought. Growers dealt with water shortages primarily by reducing irrigation frequency on crops that tolerate short term-water deficits.
Long-term solutions to overcome water shortage issues are needed and should be devised. Solutions could include the most popular option – drill another well (see Image 2) – but sometimes it takes thinking outside the box and changing how you apply water to extend your water supply. For example, a Tennessee pot-in-pot grower implemented soil moisture sensor controlled irrigation in 2012, and reduced water applications by 35 to 63 percent (red maple and dogwood, respectively), enabling expansion of production area that had previously been limited by pump capacity and water availability.
Another facet of water use relates to knowing the quality of water you apply to plants (or release off-site). Well water tends to be more consistent in quality, thus may not require frequent quality evaluation (although it’s still a wise practice), but surface waters and water from containment ponds can harbor contaminants (for example, pesticides, plant growth regulators, salts or plant diseases) that could affect plant growth. Yet a lower percentage of growers monitor the quality of surface or containment pond water sources, compared with well-water (see Image 3). Irrigation water is typically either filtered (39 percent), chemically treated (i.e. chlorination) (26 percent) or blended with recaptured water (50 percent) before application to crops.
Best management practices that include vegetative buffer strips, sediment basins and riprap have been implemented at 60 percent of ornamental nursery operations surveyed. Many growers also use aquatic vegetation and vegetative buffers to maintain quality of water entering recycling collection/recapture ponds. Yet many ornamental operations do not treat runoff water before it leaves the operation. Operations that treat water before leaving the site use vegetated buffer strips (83 percent) and constructed wetlands (17 percent).
In 2011, five in-depth group discussions were conducted at the Mid-Atlantic Nursery Trade Show, Gulf States Horticultural Expo, California Grown Show, OFA Short Course and the Farwest Show with a total of 36 industry participants.
Discussions with nursery and greenhouse managers revealed the dominant challenges related to water in ornamental crops could be grouped into
- availability (present and future),
- contaminants (plant diseases, pesticides, sediment, and salts), and
- managing runoff from production facilities (see Image 4).
Growers also identified cost savings and having increased water capacity as primary reasons to collect runoff or storm water. In addition, growers indicated the need for more information about what is acceptable water quality, cost of effective water treatment options to mitigate potential spread of disease, and sizing water retention ponds for given ornamental producers to minimize land use.
The participants’ top concerns related to water quantity or availability (such as permitting, droughts) and future government or environmental regulation. If it is necessary to stretch an existing water supply or seek greater quantities of water, producers identified updating existing irrigation infrastructure to low-volume application technology or using reclaimed municipal wastewater as an alternative water source as potentially viable opportunities. However, there were also many challenges associated with the use of reclaimed water including availability, cost, quality, regulations and community perception.
One message communicated clearly at every discussion group was the need for information stored in a central location – such as a website – to help inform decisions relating to water management, whether that decision was about increasing irrigation efficiency, installing a containment pond or selecting treatment technologies to clean water.
Themes that were common across regions in 2011 – for example, water availability (drought, permits); regulations (water quantity and water quality); runoff management – proved pertinent over the last six years, and remain relevant today and into the foreseeable future.
Clean WateR3 researchers are actively addressing water availability, quantity and runoff treatment questions through both laboratory experiments and on-farm trials. This involves multiple perspectives so that system-wide water management concerns and constraints are accounted for in the solutions recommended. Each component of the Reduce, Remediate and Recycle model integrates with the others to accomplish sustainable water resource management.
Clean WateR3 researchers focusing on “Reduce” are evaluating
- how water management influences disease presence;
- how substrate components change water movement, water holding capacity and nutrient leaching;
- which plants tolerate low phosphorus fertilization;
- pesticide formulations and application methods and how these influence pesticide efficacy and eventual runoff;
- using water footprint and life cycle assessment data to inform how changing a water management practice will influence both producer and environmental costs; and
- how irrigation type (overhead, drip, and so on) influences water movement on the production pad, both surface flow and leaching through the ground cloth.
Once runoff from production areas is reduced, then remediation of the contaminants in the water that remain becomes more feasible. Clean WateR3 researchers focusing on “Remediate” are evaluating how to remove pesticides, nutrients and plant disease propagules from runoff using a variety of treatment technologies – best management practices. Some technologies, such as bioreactors and carbon walls, that have been used by other industries (wastewater treatment plants, ag commodities in the Midwest) are simply being expanded or their applications refined to manage contaminants in nursery and greenhouse runoff alone or collectively. Other methods like floating treatment wetlands are novel, and it should be determined if they can effectively remediate plant disease propagules from runoff, while concurrently serving as an alternate production area and cleansing water.
Two research nurseries in Michigan and Virginia are helping to make connections between how “reduce” and “remediate” function together, facilitating research on a larger scale, and providing data on risks and benefits prior to industry adoption. In 2017, these two facilities are providing data on how mineral nutrient and pesticide applications are influenced by irrigation method and subsequent quality and quantity of surface and subsurface runoff after irrigation and storm events. In addition, they will investigate how runoff reuse for irrigation – with or without treatment – impacts plant growth and marketability.
After water is cleaned, it can be reused or released. The entire Clean WateR3 team is addressing “Recycle” as it involves integration of the data generated in “Reduce” and “Remediate” with socioeconomic data related to water management; most importantly, it is conveying that information to growers in a form that makes it useable. It is the job of our modeling team, who are developing a network of tools that can aid grower decision making. Tools being developed include:
- Chlorination tool – how to deliver an appropriate or target dose
- Nutrient calculator tool – per container and/or per unit area
- Plant disease risk scoring tool
- GIS-based runoff models
- Sediment/nutrient monitoring and runoff models
Life Cycle Assessment, carbon footprint and water footprint data are overarching integration tools and measures for the effectiveness of strategies for reducing, remediating and recycling water (see Image 5). Uses not only include remaining below known levels of pesticides and re-using nutrients in the runoff, but also larger picture measures such as potential environmental impact changes and changes in operating and capital costs.
Grower priorities in water research need to be regularly identified. The most recent strategic outlook on water management was reported in 2016 in HortTechnology by Fulcher and others. While water research concerns remained the same, their priority changed, with the inclusion of emerging issues.
The research areas on which the Clean WateR3 team are working are a direct result of feedback from growers. These areas are critical for water sustainability in the future – think the new norm for production practices. What thoughts keep you up at night? What do you think focused research could help you address?
We encourage you to share your ideas and concerns with us, because that’s the only way we can ensure what we are doing, or what we propose to do, positively impacts your business.
Our long-term goal is to give you a toolbox of decision support tools to help guide your water management practices. This goal has begun to be realized by the deployment of the Clean WateR3 website. Yet modeling the complex, interrelated elements of nursery and greenhouse production systems is a huge challenge, and it’s one that the Clean WateR3 team is only beginning to address. Every intricate component of your operation may not be included in the ever-expanding toolbox available on the website. However, the tools available (or soon to be available) may help you rethink the system-wide picture of water movement at your nursery or greenhouse. In turn, this may help you predict what a single change in practice could do for your operation and bottom line.
Whether you evaluate use of precision irrigation tools or remediation technologies, you will have comprehensive economic (variable and capital costs) and efficacy data to help inform your decisions. We are excited about what the future holds for water management, and hope you value the information being developed and how it can help you make decisions.
Acknowledgments: Funding for this material is based upon work that is supported by the National Institute of Food and Agriculture, U.S. Department of Agriculture, under award number 2014-51181-22372.