Minimizing losses

The use of enhanced efficiency fertilizers can have a two-pronged impact by increasing the overall benefits of fertilizer application to turf and safeguarding the surrounding environment. In short, enhanced efficiency fertilizers (EEFs) minimize the potential of nutrient loss to the environment. Slow- and controlled-release fertilizers include absorbed, coated, occluded and reacted fertilizers. All four deliver an extended, consistent supply of nutrients to turf.

“From an environmental sustainability standpoint, EEFs can reduce nutrient loss due to volatilization, runoff, leaching and denitrification, which helps not only to protect natural resources, says Dr. Eric Miltner, agronomist for Koch Turf & Ornamental, “but also means that the nutrients that you apply are used more efficiently by the plants, which is the objective of applying fertilizers.”

From a cost standpoint, EEFs can result in more efficient nitrogen uptake. More of the nitrogen that superintendents apply gets into the plants compared to non-EEFs. As a result, nitrogen application rates can be decreased accordingly, which helps offset the cost of the products. “With controlled release fertilizers (polymer coated), such as Polyon and Duration, application numbers and frequency can be greatly reduced,” Miltner says. “This not only saves labor, he explains, but also fuel and equipment wear. There are other “ripple effects.” Less time spent fertilizing means labor can be re-allocated for other uses. Employees handle fewer bags over time, which can impact injury potential, health and even morale. All of these factors contribute to the economic side of EEF use.

EEFs can reduce costs, says Dr. Travis Shaddox, postdoctoral research associate of environmental horticulture at the University of Florida. “If they do, they do so by either reducing the cost of labor, since fewer applications are required, or by reducing tonnage by increasing the efficient use of the applied nutrients,” Shaddox says. Slow-release nitrogen may reduce labor if high rates of very slowly released nitrogen sources are correctly applied. “For example, I know of a course in Florida that makes only one application of nitrogen per year,” he says. “The superintendent applies a high rate of a very slow-release polymer-coated urea in the fall. A sudden surge of nitrogen into the soil/turfgrass system may increase gaseous loss, leaching or runoff, which reduces plant uptake of the applied nitrogen. Slow-release nitrogen sources reduce this surge of nitrogen, thereby increasing plant uptake and nutrient use efficiency.”

Generally, superintendents and peer-reviewed literature report a more uniform, consistent turf quality and growth when using EEFs, Shaddox says. Gaseous loss of nitrogen can be reduced by as much as 50 percent, and leaching and runoff can be reduced by more than 50 percent in some cases.

EEFs also give superintendents enhanced flexibility by providing one product that addresses the right nutrition at the right rate and at the right time for turf. “We talk about the ‘4Rs’ of nutrient stewardship,” Miltner says. In other words, applying the right source, at the right rate, at the right time, in the right place. This implies there could be many “right” ways to achieve effective fertilization. Superintendents need flexibility because they have complex jobs with many demands and challenges,” Miltner says. “EEFs give them options to efficiently manage their resources, while providing healthy turf with great playability.”

Shaddox adds, “The value in such a program would be that the superintendent would only have to have one spreader setting and applicators would be less likely to make errors. In short, a simplified nutrient program would likely lead to a more efficient program via reduction in application error.”

Research has shown EEFs to reduce the loss of nutrients to the environment. “This has always been important, but has taken on increased significance in recent years with many states and local governments passing regulations based on reducing nutrient loading into surface waters,” Miltner says. “For decades, superintendents have used products like Nutralene, Nitroform, Polyon and Duration to build programs that use only a couple applications per year and result in healthy turf with consistent growth and clipping production. With as much time that is spent on mowing, the clipping management benefits from slow- and controlled-release fertilizers are important factors for labor and equipment management.”

A strong argument in favor of EEFs impacting sustainability and reducing overall costs of fertilization is related to the number of applications needed to be made. “For example, slow-release fertilizers may be applied at higher nitrogen rates (i.e. 1.5-pounds N/1000) for a single application to a fairway compared to a program where water soluble nitrogen sources, such as urea, may be applied weekly at 0.1-pounds N/1000 or 0.2-pounds N every other week,” says Dr. Kevin Frank, associate professor and extension turf specialist at Michigan State University. “Certainly, the costs of application/labor and other issues could be calculated for frequent applications versus a one-time application.” However, many superintendents will argue they might already be spraying fungicides or plant growth regulators, so spraying fertilizer is not really an additional application.

While The 4Rs imply there are many options for effective programs, choices still have to be made thoughtfully. “The various EEF technologies work differently,” Miltner says, “and users need to understand where they fit in.” Products with temperature-based release rates (methylene ureas, ureaformaldehydes, natural organics and polymer-coated ureas) may not be the best in cooler temperatures when a quick response is desired. If superintendents are looking for extended release, they need to match longevity with their goals; it is not one-size-fits-all.

There are EEFs that are appropriate for use at any time of the year, Miltner says. Even under very cool conditions stabilized nitrogen products like UMAXX provide quick plant response because nitrogen availability is not temperature-dependent. “You get protection against volatilization, leaching, and denitrification,” he says. Fall is an excellent time to apply Polyon or Duration polymer-coated urea. Depending upon the specific product (longevity), there is release and uptake in the fall. Release then shuts down through the cold winter months, but resumes in the spring with warmer temperatures. “A single application in mid-fall can provide nutrients well into May or June, freeing up resources to do other things,” Miltner says.

Dr. Beth Guertal, alumni professor in Auburn’s College of Agriculture Agronomy and Soil, says EEFs work well when a consistent, long-term greening response or maintenance of growth is desired. “They are another option in a nitrogen fertilization program that can include foliar application, soluble or other slow-release sources, such as methylene ureas or coated nitrogen sources,” she adds.

Consider applying EEFs when labor is low but turf quality expectations are high, Shaddox says. “Speaking strictly agronomics, nearly all EEFs are dependent upon temperature leading to a reduction in effectiveness during extremely cold or hot times of the year. When I worked in the industry, I would ask the superintendent, `When do you need your course to look the best?` I would then recommend a nutrient program based upon his or her answer.”

John Torsiello is a writer based in Torrington, Conn., and is a frequent GCI contributor.