Spread the Word

Light lines, dark spots, missed corners, neglected edges.

Sounds a lot like a bad paint job on a living room wall, but it’s not. Just as faulty brushwork can cause color inconsistencies and unattractive ceiling spots, messy granular fertilizer applications can produce similar splotches on turf.

“Keep in mind the damage that can result with misapplications, which often shows up visually in the form of striping with fertilizer,” explained Fred Kapp, technical director, Wayne’s Environmental Services, Birmingham, Ala.

And if contractors are using granular insect or weed control, misapplication results in more than aesthetic displeasure – decreased product effectiveness and unhappy clients.

The spreader was invented as a means to provide faster, more efficient applications. But a spreader, though a quite simple machine, becomes more technical when placed in the hands of a lawn care operator (LCO). To fully grasp the concept of even application, LCOs must know more than what types of spreaders are available. They must study equipment calibration, spreader maintenance and walking speed to achieve a uniform distribution pattern and proper product application rate, ultimately eliminating blotchy turf.

STUDYING SPREADERS. There are two basic spreaders that lawn care operators use today: drop and rotary.

Drop spreaders, which release product through slits straight down to the turf, have been around for many years, but were more consumer-oriented machines then, pointed out Pete Thompson, senior product manager for equipment, LESCO, Strongsville, Ohio. “They were narrow band spreaders, so whatever width they were – typically 24 inches wide – is how much product you were able to put down since the distribution pattern is only as wide as the hopper,” he said, adding that today these push spreaders drop up to a 4-foot swath of product. “Our industry needed something that could apply product quicker.”

Hence, more than 30 years ago, push rotary spreaders were conceived, and Thompson said today they outsell drop spreaders 95-to-1. With rotary spreaders, the granular product falls onto an impeller, which is broadcast to a swath of 8 to 12 feet.

Initially, both drop and rotary spreaders were walk-behind push machines. Seventeen years ago, hydraulic or self-propelled rotary spreaders were introduced to the lawn care market, the only difference being that the unit was motorized, taking the majority of the work off of the operator.

Though the different spreader types only vary slightly, their prices range from as low at $100 to as high as $1,800. Fifty-pound high-end consumer drop push spreaders cost between $100 and $125; 80-pound, professional rotary push spreaders cost between $300 and $550; 100-pound, self-propelled rotary spreaders cost between $750 and $850; and 100-pound, four-wheel hydrostatic, self-propelled rotary spreaders cost between $1,600 and $1,800, Thompson said, adding that more than 90 percent of the spreaders sold today are push rather than self-propelled.

COMPARE & CONTRAST. In terms of accurate application, drop spreaders rank No. 1 “because you can control the swath width,” Thompson said, adding that dropping product at turf edges is much more accurate with these models than with rotary spreaders because the product isn’t being thrown off target.

But ensuring an even distribution pattern can be challenging with drop spreaders, pointed out Tom Jessen, president, Perma-Green Supreme, Crown Point, Ind. “Since the product is being dropped right underneath the machine, you don’t have the luxury for a margin of error,” he said. “If you’re off by the width of the wheels, you could possibly miss a spot and with fertilizer this will result in a light green stripe. And if you over-apply, which tends to be the issue, you get a dark green stripe. These are typical application mistakes because following the same pattern 100 percent of the time is hard, especially on larger properties.

“The trick is to go over the lawn twice in perpendicular directions to minimize the chance of causing small stripes and to give you two chances to hit every square foot of turf,” Jessen continued.

However, while drop spreaders may increase application accuracy, they don’t improve productivity on the job like rotary spreaders do, Thompson stated. “On a typical 8,000-square-foot lawn, you can make about eight passes to get the job done, but with a drop spreader you have to make nearly 20 passes – application time more than doubles,” he said.

Then there’s the comparison between rotary push and self-propelled spreaders. With a rotary push spreader, maintaining a consistent walking speed, which affects impeller speed, is critical, Thompson emphasized. “If you increase your ground speed, you increase your impeller speed, which throws off your distribution pattern,” he explained, adding that the most efficient walking and impeller speed for applying product is 3 mph. “The same is true if you decrease your walking speed.”

Kapp, who uses his rotary push spreader to apply preemergence herbicides, insecticides, fertilizers and lime, said contractors need to develop a technique for stopping and starting to avoid misses and over-applications. “It is best to make sure you are at the proper speed before opening the spreader,” he advised. “Spreaders are fast, but can be less accurate due to wind and improper overlapping, which can lead to off-target applications. To prevent this, make sure you use a slight overlap, calibrate for pace, measure your volume and adjust as needed. Proper calibration is critical.” (For more information, see Calibration Competence sidebar.)

Also, Kapp keeps a hand-held spreader, which he said cost less than $30, on his truck for smaller jobs or tight spots.

Self-propelled rotary spreaders have an advantage in the instance of fatigue, aiding the operator in maintaining a more consistent ground speed, Jessen said. “And they can be a retention tool since technicians will wear themselves out less using a self-propelled machine vs. a push machine,” he added.

But these machines are also more expensive – nearly triple the investment for a regular push rotary spreader, Jessen pointed out. “That’s a big increase in cost for a machine that doesn’t increase productivity all that much on a day-to-day basis and has more moving parts so it needs more maintenance,” he said.

Also, manufacturers recently introduced combination rotary/drop spreaders, which cost about $550, Thompson said. “This machine was created with both the accuracy of drop spreaders and the increased productivity of rotary spreaders in mind,” he explained. “With today’s rotary spreaders, the hard part is keeping products off the sidewalks and driveways and out of the flower beds, so you don’t have to go back and sweep it up. This combination machine has a 24-inch drop mechanism to use next to these areas and then also has a rotary spreader application for wider expanses of turf.”

MAINTENANCE MATTERS. In addition to proper use, keeping spreaders, and especially impellers, clean is vital to maintaining accurate applications. For instance, if the lawn is damp or wet, the spreader will get wet and product will build up on the impeller, so it may need to be cleaned off more often during the day, Thompson pointed out.

A clean machine also helps maintain an even distribution pattern. “An impeller is flat and equipped with fan blades,” Thompson explained. “When the product comes out of the hopper, it hits the impeller and is flung off by a 90-degree angle blade. It’s like the wedge of a golf club, and if the wedge has product build up on it, the product will not fly out straight – it may fly up in the air. This throws off your product distribution.”

Additionally, impellers and impeller blades should be checked regularly to sustain on-target applications. “With impellers, the important thing is to make sure the gears don’t slip, resulting in intermittent flinging of product,” Jessen advised.

Worn impeller blades also negatively affect product distribution. These typically need to be replaced once or twice during the course of a season, and sometimes more frequently, depending on the product being used, Jessen said. “For instance, pelletized lime is essentially ground-up rocks, so it’s like sand or sandpaper and wears blades more rapidly compared to something like granular urea, which comes in smooth round pellets that have a greasy feel and are slippery and less abrasive,” he remarked.

The author is Managing Editor of Lawn & Landscape magazine and can be reached at nwisniewski@lawnandlandscape.com.