Equipment Notebook: April 2000, Mulch Madness

Mower blade technology has evolved from the Stone Age to the Information Age almost overnight, according to Jack Robertson, co-owner, Trim Rite Lawn Equipment, Kansas City, Mo. Advancements in blade design are helping landscape contractors improve their mulching capabilities and get cleaner cuts.

Mulching, in particular, has had the biggest impact on blade design because landscape contractors don’t want to bag grass, said Dale Marcell, product line manager for Frederick Manufacturing, the Kansas City, Mo., company that produces Gator Mulcher blades. Bagging often means more wear and tear on machinery and hauling grass clippings to a compost site, which boosts labor and fuel costs – and wastes time. “Time is money for a contractor,” Marcell said. “Hauling the clippings away is too time-consuming, and some landfills won’t take clippings anymore.”

Currently, there are 3,000 to 4,000 different mower blades on the market, Marcell estimated, which are produced by five or six manufacturers. Mulching blades are commonly used, but on occasion, contractors can’t or don’t use them. “(Their use) depends on the type of grass, which is determined by what part of the country you’re in,” Marcell said. “The blades are used more in the Southeast and Northeast and not as much in the Midwest.”

WHY MULCH? Research has shown that when grass clippings are removed, 20 to 25 percent more fertilizer was needed to maintain comparable color and quality compared to areas where clippings were returned, according to William Pound and John Street, The Ohio State University extension, department of horticulture and crop sciences, Columbus, Ohio. Clippings contain measurable amounts of nitrogen, phosphorus and potassium, and if contractors follow proper mowing practices (see “Mowing Guidelines” on page 33), the clippings will not contribute to thatch accumulation.

The advantage of using mulching blades is that they cut clippings into smaller pieces so grass doesn’t lie on top of the lawn, said Tom Weingartz, buyer, Weingartz Supply, Utica, Mich. There are many different mulching blade designs, but most are engineered to cut and then re-cut the grass, leaving tiny clippings.

“The smaller the clippings are, the quicker they decompose,” he said, adding that other factors can impact the rate of clipping decomposition. “When you cut and blow clippings off to the side, they will take a lot longer to decompose. If the grass is wet, it will clump, and then you will have to double cut.”

Still, there are drawbacks to mulching clippings. The mulching mower’s engine requires more horsepower to handle increased cutting volume, placing more demand on components, including blades, which may need to be sharpened more frequently (see “Sharpen Your Skills” on page 30). “Machines come with standard lift blades, which take less power to run,” Weingartz said. “You get more power with standard lift, but better discharge with higher lift blades. There is a tradeoff in performance.”

DESIGN DIFFERENCES. There are three key differences in mower blade designs, said Randy Harris, marketing manager, Toro Co., Bloomington, Minn. They are the material thickness, the length of the sharpened edge of the blade – the more cutting edge, the better – and the degree of the sail on the back side of the blade. Mulching blades repeatedly hit the grass blades and drop the clippings into the turf, Harris explained.

Gator Mulcher blades, which hit the market in 1994, are a hot trend among contractors. The teeth angle toward the center of the blade to redirect airflow and push the grass clippings over the cutting edge again and again. A new, heavier high lift Gator mulching blade is scheduled for release this spring, according to Marcell.

MATCHING BLADE TO JOB. Blade design impacts performance depending on what process contractors perform, Robertson said. “Different blades were made for different applications,” he explained. “The standard blade in tall grass tends to slow you down. You need a high lift.”

In the fall and spring, contractors get pickier about which mower blades they use, Weingartz said. Generally, most use mulching blades to pulverize leaves in fall and to mow grass in spring, when it’s wetter and grows faster. “In the summer, when the weather is hotter and drier, anything will work,” Weingartz said.

Some contractors will use a high lift blade to discharge clippings or to bag them. “The high sail blades can be used in the fall for leaf removal – for final season cleanup and bagging,” Harris said. “When you are trying to bag, you are always going to use a high sail.”

Some people are using the mulching blades year-round now, Weingartz observed. “They work as well on the grass as they do on the leaves,” he said. “You’ve got the best of both worlds. The blades chop up the grass and blow it out the side.”

Gator blades are a little more expensive than other types – “maybe 10 percent more,” Marcell said. Still, Robertson said they outsold all other blades combined.

WHAT’S NEXT? Marcell reported Frederick Manufacturing would be introducing 40 to 60 new blades this year. In his conversations with contractors, he said most request longer-lasting blades, or blades that don’t need to be sharpened. “All companies are looking for a blade that lasts longer,” Marcell said. “(Manufacturers) are trying some different design approaches to make them last longer.”

Despite the ballooning popularity of mulching blades, there will continue to be a place for the standard mower blade. Robertson said contractors can use standard blades for real rough cutting and tear them up. “The standard blade will never be phased out,” he said. - Ali Cybulski

The author is Associate Editor of Lawn & Landscape magazine.