The Top of Your Game
An increasing number of sports turf managers are realizing the benefits of topdressing their sports fields. Whether you currently implement a topdressing program or simply are considering initiating one, it pays off in the long run to think about what you want to accomplish and to do the work up-front to build a program that you can implement consistently over the long-term.
A well-developed, consistent topdressing program will allow you to experience the full benefits topdressing can offer, while avoiding the pitfalls that an ill-conceived program can create. Benefits of a well-designed and implemented topdressing program include:
A smoother, more level and consistent playing surface. Topdressing promotes a more uniform playing surface, which can contribute to a safer field of play.
Better thatch control. An effective topdressing program can help dilute the thatch layer so you can manage it at a healthy level. Excessive thatch layers can cause turf to be more susceptible to disease and less able to survive day-to-day issues such as temperature changes and mower scalping.
Improved soil composition. In areas where tight, compact soil conditions limit oxygen flow or water infiltration, an effective topdressing program can help create a better, less compaction-prone growing medium.
Other topdressing benefits include:
- Improved conditions for new root-zone development.
- Improved rooting of stolons.
- Protecting crown development and maintenance.
EVALUATION AND MATERIALS SELECTION
Consistency is the key to success with any topdressing program, so approach the project with the intent that the basic program you develop will be consistently implemented over a period of several years. It often takes a year or more to realize the full benefits of a consistent topdressing program, so it's critical to have patience. Also avoid the urge to make frequent changes to the mixture, frequency or other aspects of the program, as this can lead to layering of topdressing mixtures, an undesirable situation.
To be sure the program you develop is based on sound turf management principles, it's always a good idea to consult a local agronomist or university soil-testing facility regarding your soil types and which mixture of available topdressing materials makes the most sense for your turf's needs.
Today, there is a tendency to use increased sand levels in topdressing, but be sure that the mixture you use is compatible with your soil composition. Material mixtures often range from 70/30 mixtures of sand and peat to 100 percent sand. The characteristics of the sand used are very important too, so take time to locate a reliable supplier who can provide the quality control necessary year after year. Because the success or failure of your program relies on the quality of the materials used, the least expensive supplier is not always the best option.
The sand preferred by most agronomists has 60 to 75 percent of its particles in a medium-sized (0.25mm to 0.75mm) range. This promotes better retention of pore space in the soil and makes it less susceptible to compaction. Avoid larger sand particles because they can be picked up by mowers, and be especially careful that your mix doesn't include too much very fine sand (typically more than three percent), as it can choke plants off from water and nutrient infiltration.
TIMING AND FREQUENCY OF TOPDRESSING
Common situations where topdressing is integrated into a maintenance program include:
Following aerification. You can brush top-dressed material into aerification holes as a means of improving soil structure while maintaining good drainage.
To alleviate thatch buildup in newer heavy-traffic grass varieties.
After overseeding, to protect seed and encourage germination.
For rebuilding or maintaining the crown of a field.
Depending on the situation, the amount of topdressing you apply can range from light applications of
Most sports fields will focus more on a heavier application two to three times a year after aerification for leveling and changing the growing medium. Then, they will use frequent light applications after overseeding, and for thatch control. This potential for using such a wide range of spreading depths makes it important to test a variety of topdressing equipment to ensure that the equipment chosen meets the specific needs of your program.
FACTORS IN EQUIPMENT SELECTION
There is no substitute for taking the time to get out in the field and test a number of different topdressers using the materials you plan to use in your topdressing program. This is a critical step that is often overlooked, but to truly know what equipment is best for the program, it's a step that is worth taking.
When evaluating the equipment needs of a topdressing program, it's important to consider the following factors.
- Equipment size vs. area to be covered
The size of the turf area to be covered and the thickness of application will help you determine the amount of material needed and the most efficient machine to use. A helpful formula for this is the number of square feet multiplied by the number of inches deep multiplied by 0.0031 equals cubic yards required. For example, a football field (typically 54,000 square feet) topdressed at ¼ inch requires 41.85 cubic yards.
Typically, the larger the number of fields you need to cover and the more frequently you plan on topdressing, the bigger the hopper size needs to be in order to keep downtime for loading to a minimum. Many larger topdressers also have hoppers designed to be filled quickly with a front-end loader, an aid in reducing turnaround time.
Often, large-capacity topdressers can be used both for spreading and material handling, which is useful for construction and renovation projects.
- Delivery system
Spreading topdressing materials, especially those with high organic or peat content, is more difficult than it may seem. One of the key features of a topdresser is its ability to handle material regardless of composition or moisture content, which is why you should give serious consideration to the types of materials that will be run through the topdresser prior to deciding on a topdresser.
Drop-type spreaders that combine chevron or other types of patterned belts, with a rotating brush, are a popular type of topdresser for most sports turf uses. You can also use them for application of calcine clays to infields. Drop-type spreaders are popular among sports turf managers because they provide the capacity, application rates and consistency that sports fields require.
Broadcast or spinner topdressers are often used for light, frequent topdressing, as is common in many golf applications. While you can use broadcast spreaders in sports turf applications, drop-type topdressers are usually a more cost-effective choice for the task, especially considering that they can be used for topdressing infields.
- Topdresser drive type
Today, there are two methods of powering topdressers: ground-driven and hydraulically-driven. Ground-driven topdressers make even material application easier because they deliver the same amount of material regardless of changes in speed. If the vehicle speeds up, so does the application rate of the topdresser. If speed decreases, so too does application rate. Calibration of the application rate and the tow vehicle speed is not necessary with a ground-driven machine.
Hydraulically-driven equipment is also suitable for topdressing sports fields, but unlike ground-driven systems, the application rate does not change in accordance with changes in ground speed. As a result, you must calibrate hydraulically-driven topdressers against tow vehicle speed because speed variations can result in an uneven material application.
- Materials storage
If possible, you should store topdressing materials in an enclosed area, or at least try to cover them with a tarp. Benefits of properly stored materials include decreased weight and ground pressure due to a lower moisture content, and quicker integration of the topdressing medium into aerification holes (although even materials that are stored in protected areas will wick moisture and store it).
If protected material storage is not realistic, and for many facilities it isn't, the selection of topdressing equipment is even more critical. Look for topdressing equipment that utilizes a chevron or continuous pattern-style conveyor belt system. These units are designed to better manage materials with varying levels of moisture content.
THE BOTTOM LINE
Taking time to evaluate your needs and develop a sound, consistent topdressing program that addresses those needs can pay big dividends in the long-term health, beauty and safety of your sports fields.
Scott Kinkead is executive vice president of Turfco Manufacturing (Minneapolis, Minn.). For more information, or to request a copy of Turfco's report “Sports Turf and Topdressing,” contact Kinkead at (763) 785-1000, or firstname.lastname@example.org.
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