Below Before Above

This isn’t breaking news, but it remains of paramount importance to have an effective cultivation and topdessing program in place to allow more water to penetrate through the soil profile.

After a superintendent conducts a soil profile, he or she can then “put pencil to paper” and set tangible, realistic goals for organic matter management, says Nelson Caron, director of golf course maintenance at The Ford Plantation in Georgia. “The program we use here at Ford Plantation is called the OMDP, or the organic matter dilution program,” he says. “The term was coined by two USGA agronomists in the Southeast region several years ago and it’s something our team here latched onto to help us communicate with our greens chairmen and general manager.”

The “power” behind an OMDP program is that Caron and his team use science to meet the membership’s desired putting green quality. “Like many clubs, the expectations for green speeds at Ford are high,” he says. “We know and have communicated with our membership that if we are to accomplish their desired results on top of the ground, we must first perfect our below ground management techniques to be able to exceed their expectations.”

This entails disruption through coring, needle tining, and injection of sand and water. Once superintendents know what their physical soil testing numbers are, they can create an OMDP that demonstrates to their clients what cultural practices need to be accomplished to achieve the greens’ desired results. “Once these data parameters have been set, in essence, they are not disputable,” Caron says. Meaning, it takes a superintendent’s opinion out of the equation. “The cultural practices stop becoming ‘the greens were perfect then the super punched them again because he loves to do that.’ It actually becomes the opposite. Committees become educated as a superintendent explains to them the numbers behind organic matter management. This is not to say one should be without opinion, because some of the greatest superintendents in this business have also been known to be great salesmen.”

Sifting through variables

“I have always expressed to turf managers what limits the amount and timing of soil cultivation is not the soil, but the stress that is applied to the turf,” says Dr. James Crum, a professor in the department of plant, soil and microbial sciences at Michigan State University. Crum adds the variables a turf manager needs to integrate to accomplish the objectives of cultivation and the owner/manager/golfer wishes include time of year, recuperative potential of the turf, user demands, weather conditions, work force and budget. “I believe planning, flexibility and communication to all parties is important for the turf manager to be successful,” Crum adds.

Dr. Paul Rieke, professor of turfgrass soils at Michigan State University, says ask yourself are there significant layers that restrict water movement through the soil or restrict gaseous exchange or limit root growth? Is there significant thatch that must be controlled, and what management practices have contributed to thatch development?

“A related question is whether a mat layer that is high in relatively decomposed organic matter limits oxygen in the root zone?” Rieke says. “What is the rooting pattern at various times of year that might indicate a soil problem? Does the green drain poorly and why? Does the subsoil limit drainage? Is the major problem caused by sealing of the surface layer? Has an effective sand topdressing program been practiced? How deep is that topdressed layer?”

Help in answering these questions is available from consultants, such as the USGA, other agronomists or by sending samples to a soil testing lab that conducts soil physical tests. With the appropriate information, the superintendent can then embark on a management program. “If correction is needed, one must select among various cultivation tools; core or solid-tine aerification or various injection methods,” Rieke says. “More significant problems may require more aggressive techniques. Examples might be larger or deeper tines. Injection treatment could include injecting sand or other material. In some situations, a combination of treatments may be best.”

Soil types play a role in the drainage of water. Native soils with significant clay content will hold water and not allow it to drain rapidly. Sandy soils, on the other hand, will drain quickly. “It’s important in putting greens constructed on native soils to have an aggressive aeration plan with traditional aeration supplemented with deep tine and drill and fill operations to provide channels filled with sand to move water from the turf surface,” says Dr. Nicholas Menchyk, assistant professor in the department of urban horticulture & design at Farmingdale (N.Y.) State College.

There are also regional differences to consider when undertaking soil cultivation. “The turf manager needs to consider soil conditions, recuperative potential of the turf, and demand and playability of the surface after cultivation,” Rieke says. In general, cool-season grasses are under more stress when temperatures and humidity are high and warm-season grasses do not have the recuperative potential when temperatures are low. Where cool-season grasses are managed, cultivation should generally be done in spring and fall. Warm-season grasses generally in the summer.

Assessing topdressing and tining decisions

Rieke says a program that applies topdressing two or three times per year typically will not result in a thatch layer that is evenly mixed with topdressing. Infrequent topdressing does not convert all the thatch into what is referred to as a mat layer (thatch evenly mixed with topdressing). Layers of thatch “sandwiched” between layers of mat and/or concentrated layers of sand will not create a profile that is highly resistant to compaction, because the layers of thatch (regardless of how small/thin) become the limitation in the profile. Thin layers of thatch that become compacted will have an extremely fine pore system, which will retain enough water that it effectively “seals off” the profile at that depth. Water and, more importantly, air flow through that compacted thatch layers can become so slow that root growth below that depth will be limited. “The take-home message is topdressing must be applied at a frequency and quantity that continually dilutes the thatch with sand as it develops,” Rieke says.

There have been philosophical changes to the practice of topdressing in the last two decades, Caron says. “The most recent change has been with the ultradwarf Bermudagrass and super fine sands like 55, 65 and 85 sands,” he says. “These sands started hitting the marketplace about 10 years ago and became really popular five to six years ago. For the same reason, the bentgrass guys made shifts in their sand selections, so did the Bermudagrass managers with the increased popularity of the ultradwarfs.”

Selecting topdressing sands for putting greens requires in-depth examination, Rieke says. What works for one club might not work for another. And, if you are applying a specific particle size, then try and have an idea if it will adversely affect your desired outcomes. “Know what particle size distribution you are putting out there,” he says. “If you determine it might be a bad idea, try it anyway on a nursery or an out of the way spot. You might get surprised. It’s safe to say that the super-fine sands have been used for several years now and don’t show any signs of going away in the near future. The finer sands ability to penetrate dense canopies and reduce friction and drag on golf ball roll make this product nearly impossible for superintendents to ignore.”

Like many clubs, the expectations for green speeds at Ford are high. We know and have communicated with our membership that if we are to accomplish their desired results on top of the ground, we must first perfect our below ground management techniques to be able to exceed their expectations.” — Nelson Caron, The Ford Plantation

It is vital the rate and frequency of sand topdressing should be related to the growth rate of the grass, usually meaning more intensive topdressing during faster growth periods. “Most new greens grasses have high turf density, requiring special techniques to ensure the sand gets down into the turf,” Rieke says. “Higher rates of sand will be needed when using hollow or solid tine aerification. Core aerification usually leaves the green surface in a very unpopular condition with golfers.” He adds that keeping records of observations and conditions can be very helpful. The objective should be to manage the soil physical conditions so it does not limit the quality of the putting surface.

Menchyk believes it wise to use a combination of different types of tines (different diameters, lengths, hollow, solid) to achieve desired results. “In native soils or `push-up’ greens it is probably a good idea to utilize traditional aeration (1/2 inch to 5/8-inch diameter tines pulling cores) in fall and possibly spring if you have serious compaction/drainage issues,” Menchyk says. He also suggests supplementing traditional aeration with drill and fill cultivation in the fall if budget and labor allow for it, and utilize solid tine “venting” during the summer. Additionally, it is also important to break up any “plowpan” that might develop in the soil (essentially compacted soil below the normal cultivation depth that might impede water movement) with large solid tine cultivation. VertiDrain or VertiQuake are two devices that can be used.

Thought must also be given to the potential damage with any cultivation practice, says Dr. James Murphy, extension specialist in turfgrass management in the Department of Plant Biology and Pathology, School of Environmental and Biological Sciences at Rutgers University. To varying degrees, all cultivation practices are disturbing the turf and soil. More aggressive and disruptive cultivation practices pose the greatest threat for undesirable effects on the turf or soil. “As an example of this, coring during August is often done on bentgrass putting greens to avoid opening up the green during September when the germination of annual bluegrass weed seed reaches its peak,” Murphy says. “Unfortunately, combining August coring during very warm and dry weather can result in too many stresses on the turf if water isn’t restored to the turf quickly enough after coring is complete. The initially dry soil conditions become even drier during coring, especially during very warm weather, and the root system of the turf is being disturbed/damaged, which reduces the ability of the turf to keep itself hydrated. Timely irrigation is essential to prevent this scenario from developing into severe stress.”

Native soil greens may require deep-tine cultivation to improve internal drainage, although it’s not always effective. “Deep tine cultivation should not be necessary on a properly built sand-based green,” says Dr. Norman Hummel, president of Hummel and Co., a soils and turfgrass consultancy. “There is some debate that sand-based greens may not even need routine core cultivation because sands are not really prone to compaction, and that regular topdressing is all that is necessary. I have seen sand-based mixes compact.

“Therefore, until I see research suggesting otherwise, I still think some form of cultivation would be advised, Hummel says.