“Rolling, rolling, rolling…” was the refrain from the classic TV show, “Rawhide.” I am sure that Rowdy Yates did not foresee the interest in rolling turf among golf course superintendents and, to a lesser extent, sports turf managers, but the interest is prevalent and questions about the benefits and disadvantages abound.
Rolling turf is not a new concept. Dr. Jim Beard, in his Turfgrass Bibliography, cites references as early as 1928 on the benefits of rolling golf greens during establishment. Numerous other references exist from the late 1920s through today.
Four basic types of turf rollers exist. Drum-type rollers consist of one or more drums attached behind a vehicle, usually a utility vehicle, and pulled across the soil or turf surface. Some drum rollers are solid, but the majority are hollow and filled with water or some form of ballast to achieve the desired rolling effect.
Manual drum rollers are usually a single, hollow drum, which can be pulled, but more often pushed, across the surface.
Triplex attachment rollers are designed to be mounted on triplex mowers in place of the reels. These roller types often have a weight similar to the reels they replace, resulting in no compaction above that which the mowers in normal operation would cause. Operation is similar to that of a triplex mower. One innovative manufacturer markets a vibratory triplex roller, which significantly increases the desired effect.
In the late 1980s, dedicated greens rollers arrived on the market. These units are self-propelled and can be fitted with roller attachments that are smooth, grooved or other variations for specialized applications.
The fourth roller type refers to rollers mounted on high-quality mowing units to increase mowing quality. These rollers will be mentioned only briefly in this article.
Evolving uses for rollers
Rolling was originally practiced as an establishment aid and to smooth minor disruptions in the turf surface. As an establishment aid, rolling is irreplaceable. After cultivation and prior to seeding or vegetative planting, rolling helps the soil settle and identifies low spots that would have not been evident otherwise. Following planting, rolling ensures critical seed- (or stolon-) to-soil contact. If, after sodding, for example, the new sod is not rolled, air pockets underneath will cause the emerging roots to dry out, resulting in unsuccessful or uneven establishment. A drum roller is commonly used for this purpose.
Recently, however, both the triplex and dedicated greens rollers have been used to increase sand-based green stability and decrease establishment time. The vibratory triplex roller proves to be quite effective in this application.
Surface disruption of turf can be caused by a number of activities. Insects, earthworms and sub-surface vertebrates, such as moles, can all destroy the uniformity of the turf surface. In areas of the country prone to freeze/thaw cycles, frost heaving can seriously disrupt the turf surface. The twisting motion of golfers' feet on a tee or the cleats of an athlete on a playing field can also compromise surface uniformity. Supplemental cultural and management practices such as cultivation, poor cup-changing practices, etc., will also cause surface disruption. On high-quality playing surfaces, especially golf greens, this disruption can affect play and ball roll in a negative way. Rolling can help smooth the surface and, when used in combination with topdressing, can increase surface uniformity compared to turf that hasn't been rolled or topdressed.
The renewed interest in turf rolling as a routine management practice arises from the demands of the golfer for a smooth, consistent, uniform and fast (perhaps unnecessarily so) putting surface. Numerous researchers have reported a significant increase in green speed, or more correctly, ball-roll distance (BRD) with the use of greens rollers, primarily the triplex and self-contained units. Most of this research indicates that the effect is relatively short lived (approximately 48 hours) and requires repeated and consistent use to maintain the increase in BRD. Recently, work at North Carolina State University was published indicating that, although BRD increased with increased rolling frequency, plots that were aggressively rolled (4 to 7 times per week) had lower quality than greens rolled only once. This quality loss may have been a reflection of decreased stand density, which has been observed at the University of Nebraska with aggressive rolling treatments.
Although most research has been conducted on level plots, common sense and observation indicate the need for special caution when rolling on severe slopes where damage can be more than on level greens. Other work has shown that on native-soil push-up greens, the negative effects of rolling on soil structure may override the positive increase in BRD.
Other positive effects of the use of lightweight greens rollers were recently identified in work conducted at Michigan State University. Rolled plots had lower dollar spot, moss growth and bird activity (which was related to cutworm populations). These same plots, however, exhibited higher snow mold incidence. It is interesting to note that none of the previously mentioned research resulted in an increase in BRD greater than 10 inches. Perception studies at both Michigan State University and the University of Nebraska have reported that an increase in BRD must be at least 12 inches to be perceptible by the golfer. More important than the subtle difference in BRD may be the increase in consistency and uniformity of the rolled green.
Rolling can be an additional stress to turf during the summer months. Except during tournaments, rolling should be restricted to no more than twice per week. Bob Vavrek of the United States Golf Association (USGA) suggests superintendents delay “performing aggressive, routine maintenance practices, such as vertical mowing, grooming, or rolling that could further injure the turf.”
Stan Zontek, also of the USGA, cautions you to “…watch out for grooved rollers. The Wiehle roller is an excellent grooming device for creating better putting green texture and quality, compared to mowers with other types of rollers. When the grass is tender and under stress, however, the extra abrasion these rollers cause, especially on the perimeter cut, can be a major source of stress. Thus, use grooved rollers religiously when mowing the grass during non-stress times, but consider replacing them with solid section or swedge rollers when the turf is under stress.”
Turf rollers can increase establishment success and improve the playing surface of golf greens and athletic fields. However, avoid their use on wet, heavy soils and during stressful periods, such as high temperatures. Excessive frequency, especially during stress, negates any positive benefit and may result in significant stand thinning. But if you use common sense, rolling can be an effective management tool for turfgrass professionals.
Dr. Roch Gaussoin is an extension turfgrass specialist at the University of Nebraska (Lincoln, Neb.).
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