We can’t help but chuckle at the television commercial in which a gentleman with a Scottish-lilt to his voice implores a neighbor to “Feed Your Lawn, Feed It.” But, as any superintendent knows, feeding turf is one of the most important tasks in any management program. And, it’s vital to “get it right.”

The amount, type, and timing of fertilizer applications is very important to achieve the desired plant response, says USGA agronomist Adam Moeller. “Applying the wrong product, at the wrong time, and/or with the wrong rate could have very negative impacts on turf health, playing conditions and plant carbohydrate reserves,” he says.

It is critical for the proper fertilizer, the proper amount, the proper type and the appropriate time of application be followed for a beneficial application, says Larry Lindsey, senior professional sales representative for Winfield Solutions. “To fully maximize your efforts of any fertilizer application many variables need to fit together as pieces of a puzzle do,” he says. “When you’re finished, the puzzle needs to be whole and complete.”

It is very important to use the correct nutrients at the right time of the year and in the correct amounts, says Michael Pajolek, a senior professional sales representative for Winfield Solutions. It is equally important to understand what ingredients are in the bag to be sure that they will work at the time of the year the application is made. “Some ingredients, such as methylene ureas, release by a soil bacteria and will really not be effective under 55-degree soil temperature,” he says. “Other ingredients release by a temperature-related breakdown and they can double their release rate with a 10-degree increase in soil temperature – probably not the best choice going into July and August.” Still, other ingredients release by hydrolysis, meaning they require moisture to make the release happen. Often, these release characteristics are not taken into account at the time of purchase.

With the exception of managing greens, superintendents often adopt the “it’s worked in the past” attitude and may not put a lot of thought into the fertilizer they’re using, says Dr. Eric Miltner, agronomist for Koch Turf & Ornamental. “They spend more time thinking about things like diseases, insects, localized dry spot, irrigation, growth regulation, etc.,” he says. “I would encourage all superintendents to critically evaluate their fertilization programs, and see if they can find ways to do it better. Maybe they can, maybe they can’t, but don’t just take it for granted.”

Developing an overall fertilizer program and course management strategy based on efficiency will, in the final analysis, be cost effective, says Dr. Gordon Kaufman III, technical manager turf and ornamental for BRANDT/Grigg Brothers. Employing this sage strategy, superintendents will use the correct amount of fertilizer, thus conserving man-hours. “Complete and balanced fertilizer, both dry and liquid, will take less time to prepare, mix and apply,” he says.

The best time of the year to fertilize depends on the variety of grass on the course and the weather conditions with respect to temperature and moisture. “For warm-season grasses, you should probably avoid the extremes, i.e. too hot, too cold, too wet, too dry,” Lindsey says. “These conditions produce poor growing environments. They also interfere with how the minerals interact with the plant and the soil.”

Grass variety and weather are two critical factors when determining the best time of year to fertilize.
© Turfex

Foremost in any fertilization program is soil testing because it gives the superintendent a beginning picture of what levels of nutrients are present, however, it doesn’t necessarily mean they are available at this time. You can now build a nutritional program, says Al Czapski, Winfield Solutions’ senior fertilizer product manager, professional products group

While nitrogen is not analyzed in a typical soil test, turf managers need to develop a nutritional program based on turfgrass requirements. Those are based on factors such as cultivars, intensity of play, mowing height, geographic location, weather and budget. “It is difficult to make a broad recommendation on fertilization, but the key element on any turfgrass nutritional program is nitrogen,” Czapski says.

Because there are so many different grass types, climates, soils and use patterns in golf, it’s nearly impossible to establish one set of fertilizing guidelines, says Dr. Doug Soldat, associate professor in the University of Wisconsin-Madison Department of Soli Science. “I’ll take the classic professor route and say it depends,” he says. “You need to understand those factors above to determine the best timing for your site and situation. In general, however, researchers have begun to question the utility of late fall nitrogen applications in the northern United States. These were once touted as the most important for turf health, but the research done by folks like Dr. [Karl] Guillard at UConn, Dr. [Marty] Petrovic at Cornell, and myself and Dr. [Brian] Horgan (University of Minnesota) has shown that nitrogen losses are much more likely during this time period and that the size of the application should be reduced or eliminated.”

Soldat recommends not fertilizing once ET has dropped to negligible levels in the north. “Most of the nitrogen gets to the plant root via mass flow, which is the flow of water in the soil to the root driven by ET,” he says. “Once ET stops – cold weather, short days – nitrogen uptake drops off substantially. It doesn’t make sense to apply a soluble fertilizer at this time.”

Pajolek, who does much of his work in the Northeast, recommends applications around May 15-June 15, Aug. 15-Sept. 15 and Oct. 15-Nov. 1. “Three, one-pound applications will provide a great base to work from,” he says. “You can supplement from there with liquids and water solubles in conjunction with fungicide applications.”

One of the common fertilization problems is not applying enough nitrogen, Soldat says. Turf needs nitrogen to replace the leaves lost by mowing and wear traffic. Sometimes thin and weak areas can be improved by increasing the fertilization. “A lot of people are worried that increasing nitrogen will slow down green speeds, but an extra pound per thousand square feet will only decrease green speeds by four inches – less than a typical golfer can detect,” he says. “A pound of nitrogen can really make a difference in terms of turf health.”

Streaking, speckling or spotting, and burn are all signs of improper application, Miltner says. Each can indicate either application errors, or possibly fertilizer blends that don’t fit the situation or were used improperly. Likewise, peaks and valleys in growth or color could indicate bad program timing, or maybe just the wrong product for that application.

Adjusting a fertilizer program is more appropriate than attempting to directly remedy a problem, Moeller says. “Superintendents should closely examine how the turf has performed and if any of the signs mentioned in the previous question have been a chronic problem,” he adds.

Performing soil tests for nutrients combined with measuring clipping yields is helpful in determining where adjustments are necessary. It is also valuable to evaluate how PGR programs are used in conjunction with fertilizer applications. Superintendents must balance turf health with playing conditions so fertilizers and PGRs need to be used appropriately to ensure both turf health and playing conditions meet expectations, Moeller says.

There are many high quality slow- and controlled-release fertilizers that release nutrients over periods ranging from six weeks to six months. “Superintendents have a lot of choices to design their programs for as many or as few applications as they want,” Miltner says. “Programs with fewer applications obviously save time and labor, but there are other benefits that might not be as apparent.”

Known as enhanced efficiency fertilizers (EEFs), these fertilizers are also more efficient at delivering nutrients to the plant than quick-release sources, such as urea or ammonium sulfate. In other words, a higher percentage of the nitrogen you apply actually gets into the plant when you use EEFs. Therefore, annual nitrogen rates can be reduced. This means less wear and tear on equipment, less fertilizer to transport, less time applying product, and fewer bags to lift and handle, Miltner says.

Enhanced sprayer technology will probably have the most significant improvement in fertilization application accuracy and cost savings, Moeller says. “This technology can ensure the most accurate applications and ultimately apply certain materials only in areas where deemed necessary via nutrient analysis,” he adds.

Environmental conditions “being equal,” says Kaufman, formulations built for nutrient use efficiency, controlled release or those that are foliar targeted will increase efficiency, thus reducing costs. “Biologicals such as plant metabolites and plant growth-promoting rhizobacteria (PGPRs) have shown promise to improve nutrient use efficiency and promote plant health effectively during periods of abiotic stress, specifically drought and high salt conditions,” Kauffman says.

Your turf is hungry. That you know. It’s a matter of feeding it the right fertilizer at the proper rates and at the optimum times of the year to keep it satisfied and healthy.