Originally published by Golf Course Industry on Feb. 26, 2018
Slow- and controlled-release fertilizers protect against feast-or-famine cycles, minimize environmental loss, provide consistent play, and cut costs.
Keeping turf nourished and healthy with the right amount of fertility is a huge part of proper golf course maintenance. But golf course superintendents must consider many factors in choosing their fertilization products, not the least of which is their budget.
"Superintendents should think about three major things when figuring the cost of fertility -- performance, how a fertilizer is made and how long it will last," says Dr. Eric Miltner, agronomist with Koch Turf & Ornamental. "What goes into the bag is extremely important."
Miltner encourages superintendents to ask their blender or distributor for a spec sheet and discuss what's in the bag with their sales representative. What nitrogen source is used -- urea, ammonium sulfate, methylene urea, or polymer-coated urea, for example? What potash source is used? How much filler is added?
"Filler is usually ground limestone which has little to no nutritional value," adds Miltner, who has a doctorate degree in agronomy from Michigan State University. "If superintendents find they are paying for filler, they should ask for a higher analysis product to get better value for their money."
For example, compare a 16-0-8 NPK blend to a 32-0-16 NPK blend. Both have the same ratio of nitrogen to potassium and both deliver the same nutrition. But a superintendent will have to spread twice as much of the first blend than the second blend.
"If you want to put out a pound of nitrogen per 1,000 sq. ft., you'll have to spread about 3 lb. of the 32-0-16 blend, whereas you'll spread more than 6 lb. of the 16-0-8 blend," explains Miltner. "With the lower analysis blend you'll use more bags, take more time, use more material and spend more on labor, in addition to putting more wear and tear on equipment. Many intangible costs are associated with spreading more fertilizer."
Consider the Source
Another important component of what's in the bag is the nitrogen source, says Miltner. Keep in mind that a slow- or controlled-release nitrogen product might last four or five months. A more soluble, faster-release source can result in nutrient loss through volatizing into the air or leaching into the groundwater. The controlled-release product might cost more per bag, but the product works much more efficiently and more nutrition gets into the plant over a longer period of time.
"The term Enhanced Efficiency Fertilizer (EEF) refers to fertilizer products with characteristics that allow increased plant uptake and reduce the potential of nutrient losses to the environment," says Andy Drohen, Koch Turf & Ornamental senior regional sales manager for the northeastern U.S. and eastern Canada. "Although the term EEF is relatively new, products that fit this classification have been around for decades, including methylene urea, sulfur-coated urea and polymer-coated urea products."
When superintendents apply EEF products, they can make fewer applications per year on the golf course, adds Drohen. "The result is a steadier feed with no peaks and valleys and no feast-or-famine cycles," he says. "You give the turf a little bit of food every day rather than applying it on Monday and having it gone by Friday…and then having to wait a few more weeks for another application."
Controlled-release, coated nutrient sources include the products known as polymer-coated fertilizers. The manufacturing process involves coating a readily available nutrient such as urea or sulfate of potash with a polymer coating. One example is DURATION CR controlled-release fertilizer.
Applying a Baseline of Nutrition
"You can put out polymer-coated products in the spring and they will carry you all summer long, applied at the right rates," notes Drohen. "There are superintendents who like to use soluble nitrogen sources, which are dependent on the weather for activation. We recommend they go out with a pound of nitrogen with DURATION CR in the spring. That gives them a baseline of nutrition so if it's too wet and they can't apply liquids, the turf still has nutrients to rely on."
For example, Drohen had a customer who was putting out 8 lb. of soluble potassium on greens each year. By switching to a polymer-coated product, the customer reduced his potassium rate to 4 lb. per year, made in two applications during aerification in spring and fall. "It was more efficient and he got better results and spent less money at the end of the year," adds Drohen.
The trend toward using more liquid fertilizers grew out of using spray programs, first on greens but then on fairways too, says Miltner. "It is convenient to add a liquid fertilizer to your spray program, but there's still a cost [associated with] applying fertilizer every few weeks," he adds. "We encourage superintendents to look at their costs and calculate a more efficient way to fertilize. Using granular controlled-release products only once a year on fairways can actually be more economical."
Research has shown that polymer-coated products release nutrients at a pace plants can use them. They are environmentally responsible with low potential for nutrient leaching, denitrification, runoff and volatization, notes Miltner. Many states have begun enforcing best management practices (BMPs) to regulate nitrogen use in turf. Those BMPs can often be addressed with the use of controlled-release products.
"Consistency of playing conditions is something that's taken on much more importance in golf in the past 15 or 20 years," notes Miltner. "Using slow- and controlled-release products really improves consistency of turf growth, which in turn improves consistency of golf play. That's important to golfers and superintendents want to provide it."
Avoiding the feast or famine cycle, minimizing environmental losses, providing consistent play and maintaining healthy turf. Superintendents can achieve all of these factors while keeping costs to a minimum with slow- and controlled-release fertility products.