Water Smarts

Irrigation is typically applied to minimize crop damage and optimize plant growth, often with little consideration that water is a limited resource. In addition, water applications are scheduled to allow access for laborers, application of agrichemicals and to minimize disease.

Using water efficiently has only recently become a consideration for many growers. The majority of nursery and greenhouse operations assume that their supply of water will be relatively stable for the next five to 20 years. However, some ornamental plant producers have recently encountered water shortages and have begun to rethink water storage and use. Therefore, long-term water supply is probably one issue all growers should move to the top of their “food-for-thought” list. Water allocations for irrigating crops will remain the same or decline in the future given the current legislative and water resource realities.

Over the coming years, the use of ground water will be increasingly limited, and the use of surface and/or reclaimed water, which is often of lower quality due to salts and other contaminants, will increase.

What are you doing at your operation to prepare for the possibility of reduced water quality and quantity? Are you prepared for the next drought? Consider this: In the 20th century, the population of the United States increased by 300 percent, while water withdrawals increased about 700 percent during the same time period. When it comes to water-supply decisions regarding water for plants or people, people often win.

East versus West
Water allocation and regulation are approached differently in the eastern and western parts of the United States. In the arid and semi-arid West, water rights are typically based on historical rights. People or cities that have been there longest have first (a priori) claim/access to water, as long as it does not negatively impact other users. The difficulty is defining what constitutes a “negative impact.”

Water rights in the West have been a long-standing issue, whereas in the East conflicts over water are much more recent. Water is more abundant in the East, and water rights agreements did not begin until the mid-20th century and were aimed at facilitating the sharing of information about water quality. More recently, though, legal battles have started in the eastern U.S. for surface water rights in rivers that flow between states such as Georgia and Florida, Georgia and Tennessee, and North and South Carolina. Georgia is currently suing Tennessee, claiming that when the boundaries of the states were drawn some 200 years ago, there was a mistake which excluded the Tennessee River from Georgia. Access to the Tennessee River could provide additional water for Georgia’s growing population. Although current legal and regulatory focus is on surface waters, concerns exist that groundwater may become an additional source of conflict in the near future.

In both the East and the West, improving or protecting the quality of water entering rivers and other bodies of water is now a priority. California, Florida and the Chesapeake Bay (which includes parts of six states and Washington, D.C.) have recently implemented Total Maximum Daily Load Limits (TMDLs), which define the maximum amount of certain pollutants that can enter a water body. The best time to prepare for a storm is before it hits, so there’s no time like the present to begin planning to address reduced water availability (whether drought- or regulation-based), poorer-quality water and/or runoff-management requirements.

Addressing availability
To gain a better understanding of a variety of water-related issues, a national survey of the ornamental industry was conducted in 2012. Out of the growers that responded, almost 40 percent stated that either their water volume or quality fluctuated during the year. Developing on-site water storage capacity can supplement water availability for blending with fresh water or simply to maintain adequate volume. Stored water from storm and/or irrigation runoff can be reused, thereby reducing use from wells, surface, municipal or other sources.

A little more than one out of three growers surveyed currently store water on-site, with most (68 percent) using containment ponds and 36 percent using tanks or cisterns (see Figure 1).

The main reasons growers listed for storing water were to have water available during droughts, as well as to be able to maintain volume and flow rates for daily irrigation.

Although water storage does remove land from production, it provides water security for your operation. Having on-site storage is a relatively inexpensive “insurance policy,” compared with the loss of plants due to lack of water or the expense associated with trucking water in from outside the operation. One operation in Maryland spent nearly $100,000 in 2007 to truck in water to save more than $1 million worth of inventory during an extended drought. This drought resulted in many mid-Atlantic growers — including the aforementioned Maryland grower — installing containment ponds in an effort to prevent future water shortages.

When asked about the most cost-effective way to obtain more water for their operation, more than half of growers surveyed would drill an additional well. Other options were to install containment ponds (30 percent), add rainwater collection (21 percent) or implement storage tanks (17 percent) (see Figure 2).

While adding a well might seem to be the most cost-effective option, groundwater resources are already being limited by increased urban withdrawal/demand, reduced permit volumes by state agencies, and increased cost/taxes on pumping. For these reasons, surface-water capture and storage is becoming more economically viable for a wide range of growers.

John Majsztrik is a post-doctorate researcher at the University of Maryland, Sarah White is assistant professor, Nursery Extension Specialist at Clemson University, Jim Owen is assistant professor, Nursery Crops Virginia Polytechnic Institute and State University (Virginia Tech), and John Lea-Cox is professor and nursery research extension specialist at the University of Maryland.