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The Evolution of Aeration

by Paul Hollis

Perhaps the biggest development over the last half-century is the mechanized coring aerifier. Photo courtesy of Redexim Charterhouse, Inc.

Aeration is one of the most important cultural practices that a golf course superintendent can do to establish and maintain their facility. It is a widely known practice that goes back to the days of legendary greenskeeper Old Tom Morris. The play on St. Andrews Old Course back then was limited to one or two dozen rounds per day, so Old Tom relied on earthworms to create his aeration holes. The regular practice of soil aeration to loosen and warm the soil was recognized by United Kingdom greenskeepers as far back as the 1890s.

The use of mechanized machines to cultivate soil was invented for agricultural application starting as far back as the 1870s. While the machines were still steam-powered at that time, they were advanced compared to anything being used on golf courses. A century of innovations in golf course aeration was just around the corner.

In the 1900s, Horace Hutchinson started recommending the practice of lifting soil with a pitchfork as a way to relieve compaction. The invention of the original deep-tine machine, the Verti-Drain, in the 1970s, was an innovative version of this century-old practice. The Verti-Drain brought many old compacted greens back to life that might have been otherwise pushed aside and rebuilt.

In the 1930s, a greenskeeper at Mission Hills Country Club named Chet Mendenhall invented a machine called the Turferator in Kansas City, Mo. This machine consisted of two rows of drills that were 5 inches long and operated by a motor that lowered the drills by using a trip mechanism. This was the forefather to today’s modern drilling aerification machines. The current drill-and-fill machines are a popular way to improve surface and subsurface drainage.

Additionally, a spiking machine with tines mounted onto a roller was designed and built in the United Kingdom by Hargreaves and Company. This and other early machines were typically pulled by hand or with a horse. This mild cultivation practice was often combined with overseeding.

In the 1940s, a man named Tom Mascaro was best known for inventing a machine that revolutionized the process of aerification. Mascaro invented a device called the Aerifier in 1946, and the drum-style machine made aerification a common practice on golf courses around the country. This machine later developed into today’s simple tow-behind machines that allow the interchange of coring spoons, slitting blades (both triangular and rectangular), flex blades and more.

Perhaps the biggest development over the last half-century is the mechanized coring aerifier. Golf course superintendents around the world have used the common reciprocating design offered by many of today’s equipment manufacturers. The machines were slow and cumbersome as recently as the 1970s, but recent advancements have led to deeper, faster and more efficient machines. Greens aeration no longer requires five to six men a week to accomplish.

With its inception in the 1980s, the Aera-vator machine introduced a new style of aeration using vibratory tines that was unlike anything seen before. A row of tines twist and turn to fracture the soil without punching holes like other machines.

Slicer aerator. Photo courtesy of Redexim Charterhouse, Inc.

In the 1990s, an aeration machine called the Hydroject used a revolutionary method of injecting water at high pressure to relieve soil compaction. Water injection was popular when first introduced because there was little damage to existing turf, and it left a clean putting surface compared to other types of aeration.

The concept of linear aeration, otherwise known as deep verticutting, made some dramatic improvements in the late 1990s with the introduction of machines that created closely spaced channels in shallow depths. The high-speed cutting action of these machines caused negligible damage to golf course greens, but removed significant amounts of thatch and root growth. While linear aeration by definition is aeration with a constant slit, this could also include some of today’s shallow-slicing machines that are effective is cutting stolons and rhizomes.

While rotary decompactors were well-known in Europe, the alternative type of deep aeration was not widely accepted in North America until the turn of the 21st century. These machines use thick, tapered blades to cut cleanly into the soil and often provide a shattering effect by moving soil in one direction then the other. The machines are also adapted for use as root pruners and for channeling drainage.

Originally developed in the early 1990s by Scott Bjorge of Owatonna Country Club, the PlanetAir aerator has a primary shaft that rotates in the opposite direction of travel, while the planetary gear counter-rotates the aeration knives in the forward path.

Greens aerification using the Terra Spike XF-6 by Wiedenmann. Aerification depth to 8.5 inches with 5/8-by-10-inch coring tines at an operating speed of 1.2 mph with 2.5-inch square hole spacing. Photo courtesy of Wiedenmann.

In the late 1990s, a new concept of aeration, the AerraGreen, was introduced. The machine forces air upward from depths up to 12 inches, and it promotes deep, dense root growth. The Aer-aid system is another aeration tool that forces compressed air into the rootzone, but in a way that is uniquely its own. The air is injected through tines with a machine that penetrates up to 6 inches deep.

The DryJect machine injects soil amendments while aerating and topdressing in the same pass. Its technology uses water to fracture the soil while injecting large volumes of dry material. The Waterwick machine injects gravel veins into soil with multiple vibratory plow blades carrying away excess water in wet areas. The SandMaster is a one-pass decompactor and slit-drainage machine. Its unique vibrating tine system allows the use of wet or dry sand, gravel or various soil amendments.

It would be unfair to disregard the development of tines, blades and attachments that have also seen dramatic changes over the years. It is now possible to choose from coring tines (top eject and side eject), solid tines, needle tines, drilling tines and others. The industry now has tines that can last 18 greens with the invention of carbide tips. It is now possible to aerate turf with a selection of tines in depths and diameters that range from the size of a small hypodermic needle to those that are as large in diameter as a small irrigation pipe. Superintendents seem to be looking for smaller coring tines that are spaced closer and closer in order to affect more surface area on golf course greens. It has been suggested that the smaller the tine, the faster the healing time. However, when planning to change a soil profile, the fastest way to do so is to use the deepest and largest diameter tine possible with a hole spacing as close as the root depth will allow.

First Products’ Aera-vator uses a solid-tine vibrating action to break up hard, compacted soils without disrupting the existing turf. Photo courtesy of First Products.

The USGA has said for years that all aeration is good. It is recommended that the methods, depths and hole size should change often. This prevents a hardpan layer from forming, opens new channels within the soil for nutrients, and allows oxygen and water to have an easier path to the root system. The old saying to “vent, vent, vent” could never be truer than it is today, and there are more mechanical means of aeration than Old Tom Morris could have ever imagined.

With aerification having become a practice that is now known as standard over the last century, it is no surprise that mechanical means of performing the practice have made leaps and bounds, as well. However, it seems over the last few years that manufacturers have been challenged to make aeration machines that go faster and deeper than ever before. Many of today’s superintendents are pushed to squeeze in more and more rounds of golf to increase revenues. While aerification is a proven necessity, shutting down the golf course for aeration is a luxury that many do not often have. Some also seem to be looking for machines that can perform more than one task, pulling cores while collecting them is one example, aerating and topdressing at the same time is another. With the requirement of the customer changing, I am certain that the innovative technology we have seen from many of the industry’s top manufacturers will certainly continue for years to come. It is not out of the question that the coming years will see products that are true multitasking machines, and equipment that can complete the job faster and better could be just around the corner.

The author is executive vice president for Redexim Charterhouse, Inc.