Editor’s Note: As the industry continues to grapple with water management and conservation issues, GPN aims to spark more dialogue — and share important information — regarding this crucial topic. This is the second installment of a two-part series, written by members of the North American Horticulture Supply Association’s (NAHSA) Water Issues Task Force, providing growers with information they can use now to prepare for challenging times ahead.
Last month, we explored the problem sources that have led to our current water crisis and set the stage for a more sustainable way forward. The unprecedented water woes impacting — and reshaping — our industry present both a challenge and an opportunity to take responsibility and take action. From innovative irrigation technologies to plant selection and consumer education, growers have the resources to dive in to the challenge and help protect our livelihood and our planet. The time to act is now.
While concepts that allow growers to conserve water have been around for 20 years or so, significant improvements in recent years are making higher performance systems more affordable with faster returns on investment. Growers concerned with the sustainability of their operations can take advantage of these developments and upgrade their irrigation system and practices to minimize use and maximize efficiency.
The key to modern watering technology is water placement and management control. Instead of watering an entire area where plants are located, modern watering systems can deliver water directly to the container of each plant. This basic step bypasses the largest water wasters: water that would otherwise fall between the plants and become runoff, wind drift and evaporation. Subirrigation, new capillary mat designs and water recycling technologies also offer opportunities to both reduce water waste or loss and reduce runoff from the operation. Advancements in options and flexibility of control systems, along with improved water placement technologies, means greatly increased ability to apply water only where it is needed, when it is needed, in the quantities needed.
The “best” water placement technology varies by application: hanging baskets, bench pots, plugs, etc. For widely spaced plants, drippers and spray stakes are common. For tightly spaced small containers, overhead watering with booms or sprinklers may be more cost effective.
Subirrigation and the newer capillary mat technologies can be used for many sizes and types of crops. In all cases, uniformity of delivery is key. Any time uniformity is improved, the net result is water and fertilizer conservation — normally accompanied by improvement in overall plant quality, too. Growers who are serious about improving water delivery efficiency can get started by conducting an irrigation technology audit with a trusted supplier to determine opportunities for improvements at their operation.
There are additional actions growers can take to reduce water waste and increase the efficiency of their irrigation practices. One simple and inexpensive measure is to install additional shut-off valves on emitters and wherever you might be able to turn off part of your system while still using the rest. There is no need to have water dripping from tubes where plants have been removed. While a bit more expensive, using pressure compensated drip lines usually results in water savings and more uniform delivery of water. Even small actions, like installing shut-off valves, are important because they reduce water use and demonstrate conscious attention to water conservation.
Water management control systems also have improved, both in their ability to provide simple, inexpensive automation to small operations, and to manage the complete water and fertilizer needs of mammoth operations, with dozens of fertilizer injectors and hundreds of zones. Also on the horizon is the use of soil-moisture sensors as part of irrigation control systems so that irrigation is increasingly plant-needs driven. Research being conducted by Drs. Marc van Iersel of the University of Georgia and Stephanie Burnett of University of Maine is showing possibilities of reducing the amount of water used to produce a crop by as much as 80 percent as a result of irrigating according to plant need and substrate water status. This approach also minimizes leaching which contributes to the reduction in water use. Van Iersel’s research was presented last month at the Southeast Greenhouse Conference. Bottom line, technology is now available to help you better control your irrigation practices for the benefit of your plants, water conservation and, ultimately, your budget.
Optimizing efficiency of the irrigation system is certainly a key factor in dealing with drier times ahead. However, it is not the only factor. How the growing media accepts, transfers and releases water is another major, and often overlooked, aspect of total water demand and consumption. Understanding the changing dynamics of growing media provides growers with additional opportunities to increase efficiency, conserve and be environmentally responsible.
While peat and other media components may have very high potential water-holding capacities, they become water repellent and extremely hard to wet or rewet once they have dried. This loss of wettability is not an all or nothing situation. Between fully wettable and completely water repellent is a gradual loss of wettability that causes runoff, non-uniform wetting, excess leaching, and significantly increased demand for and use of water.
Using media surfactants, or wetting agents, is the only reliable way to restore wettability to water repellent media. Gel materials help increase the potential water holding capacity of the media which can be valuable for certain crops. Wettability, however, is also vital for maximizing results from use of gels. While most growing media contain a wetting agent at the start, and many growers add one if mixing their own media, that initial charge is not sufficient for a full production cycle or for post production wettability.
Regular use — small amounts applied with liquid feed — can avoid the development of water repellency and maintain good wettability throughout production and into the retail environment. While the most important consideration here is that significant water savings are possible, the fact that the cost of the surfactant is easily covered by reduced water and energy costs makes this a sensible as well as sustainable practice to employ.
Hydrozoning, or grouping plants according to water requirements is another practice that can significantly reduce water use as well as labor and potential for overwatering certain crops. This applies in commercial greenhouse and nursery operations as well as in retail settings. A related opportunity is to recommend the same to consumers so that they can have successful gardens and practice water efficiency as well.
Even with upgrading irrigation technology, ensuring media wettability and organization of crops by hydrozone, maximizing efficiency and reducing consumption comes down to watering practices, such as deciding when to water and how much water to apply. Using technology and practices that call for irrigation only when it is really needed can avoid unnecessary consumption, excess leaching and waste of fertilizer as well as reduce potential for environmental contamination. Whether you use moisture sensors, indicator plants or feel — and however you consciously determine how much water to apply — the indicator areas should be operating optimally and be representative of the rest of the area.
Training is absolutely vital for successful crop production with as little water as possible. It can take some time to go through the exercises to spell out the indicators and actions to follow for determining when watering is needed and how much is sufficient. Taking the time to do this and then training the people who determine actual daily water use to follow the guidelines is ultimately one of the few ways to really understand how to grow with less water.
Water Harvesting and Runoff Collection
Another way to prepare for water quantity and quality restrictions and regulations is to implement practices that allow you to reduce the amount you require from the community “grid,” especially during drier periods of the year. Building reservoirs that can be filled during wetter times of the year — and which can also harvest both rainfall and runoff — can provide extra water supplies for times of higher water demand. While the amount of water collected this way is not likely to provide all the water you need for irrigation, it can reduce your requirements during typically drier times. Capturing runoff has the double benefit of providing you with water — and maybe fertilizer — to reuse and reducing the potential for nonpoint source pollution from your operation.
A Bold Approach to Plant Selection
Consider only growing or selling plants that are water sensible for the locations where they will be used. While this may seem a somewhat radical move that takes some getting used to by growers and consumers, this could be a huge win-win-win action overtime: win for the grower and retailer in water savings in production and in-store maintenance, win for the consumer in plant performance and water savings, win for the environment. This is an idea that, while bold, would certainly show that the growing industry can be a leader in practicing and promoting sustainable beautiful gardens and landscapes.
Education and training is vital because, ultimately, water consumption or conservation is in the hands of the person holding the hose. Ownership and management are where a commitment to conserving by increasing efficiency and reducing waste must start, however the success or failure of that ideal depends on people at every level. Providing your employees with education and training on efficient water use and conservation can build understanding and buy in. A base of informed and cooperative employees can go a long way toward surviving present and future water woes.
Another huge opportunity for education is with the consumers of our product. Often plant sales decline because homeowners are prevented from watering by regulations or are afraid that they will not be able to keep the plants alive. As was frequently mentioned at the recent Southeast Greenhouse Conference, when policymakers see — or hear about — water being irresponsibly used by homeowners, they implement watering restrictions, and that really hurts our business. So this education opportunity is not only huge from the standpoint of helping customers be successful with plants, it is key to keeping plant sales flowing. The focus here needs to be the right plant in the right place managed the right way.
It is often said that if it is not written, consider it “not done” or “non-existent.” Popular truism is the saying that if you don’t measure (record) it, you cannot manage it. To properly prepare for drier times ahead, keeping a record of both the amount of water actually required to grow crops, the amount of water actually used and the practices being used for efficient irrigation are important. Monitor your water use. Avoiding measuring how much you are actually using only means you will not have the information when authorities ask for it or require metering. Start now, and look for ways to reduce consumption without compromising crop quality. Record training meetings, and have all present sign a simple sheet of paper that they were there. Documentation requirements are likely to increase in the future and having documented information can be a big help in the face of developing regulations.
These records will show that you know the absolute minimum amount of water you require and that you have taken measures to maximize efficiency and minimize waste and overall use. This kind of information has helped companies in states where drought caused water rationing. Those who could show that they knew what they needed and were using as little as possible faced fewer restrictions than those who had nothing to validate their case.
Shaping the Future
Growers in states previously faced with water woes talk about their struggles when they were facing and fighting restrictions on their own. Likewise they talk about the progress that was made once they combined efforts with other growers, related green industries and even the legislatures to work together and speak with a unified and informed voice. Getting organized and functional, before you face a crisis, will greatly increase the chances of negotiating a fair deal as water regulations and restrictions increase.
Note From Authors: New information, technologies and practices are coming forward all the time. NAHSA, the new Nursery Floriculture Common Interest Group within The Irrigation Association and, of course, GPN will aim to keep bringing this information to you as it develops.