Topdressing is a thin layer of material designed to stay loose and resist compaction. The layer should be between ¼” to ½” in depth. Any deeper and it will negatively affect ball bounce and player traction. The topdressing layer has many benefits to the infield. Most importantly, it assists in moisture management and provides resiliency on the surface of the skin. It allows you to re-enter infields sooner after a rain and gives you the capability to add more water to the infield skin without making a muddy mess, provided you are working with a proper base soil for your infield.
An infield skin topdressing works much like mulch in a garden — it shades the base soil from direct sunlight, which helps to slow the evaporation process from drying out the base soil. The base soil is where you want your moisture on your infield to reside in order to provide resiliency to the infield surface. The composition of your topdressing will also help this process as well. Different topdressings do different things. Some absorb a lot of water, while others absorb little — if any at all.
What’s the difference between topdressing materials?
There are essentially 4 different types of topdressings. Each have their own characteristics.
Montmorillinite and Illite clays fired to 1200˚ to 1400˚F. Very absorptive but somewhat lightweight and can blow around in 25 mph winds if particles are dried up.
Brands: SAF 816 Field Conditioner, SAF SureDry Drying Agent, Turface, Diamond Pro, Pro’s Choice, Mule Mix
Vitrified Clays & Lightweight Aggregates
Natural products fired to high temperatures of up to 2000˚ F which can include clay, expanded shale and crushed brick. They are about middle of the road when it comes to absorption but can hold their own with wind until you see speeds above 30 mph.
Brands: ProSlide, Diamond Pro Infield Conditioner
Crushed non-fired stone products such as decomposing red granite, shale and many others, are usually very heavy. Therefore it stays in place for the most part, but absorbs little water
Brands: Magic Mix, SAF Coat
The most absorptive, but it is very light so it moves very easily in heavy rains and high winds.
Choosing the topdressing that’s right for you
Choosing topdressings for a field is often dictated by weather and groundskeeper preference. In drier climates (Western US) with low humidities, high heat and/or breezy conditions, you want your topdressing to hold more moisture at the surface. This slows the evaporative process from getting down to the base soil in the profile. The more moisture your topdressing can hold, the longer it will take evaporation to reach the base soil. For this situation, you’ll want to use topdressing materials that can gorge themselves on water and hang on to it. Think calcined clays.
Conversely, in more humid regions of the U.S. (the eastern two-thirds) where more frequent rains and higher humidities are common, you may want the topdressing to be able to dry out a little quicker so you can re-enter your fields more quickly after rain situations. Start with topdressing materials that don’t have a lot of moisture holding capacity. These include vitrified clays, expanded shales and crushed aggregates. If while using these materials your infield skin topdressing is drying too quickly, you can hold more moisture in the topdressing layer by adding calcined clay to it. Add a little at a time until you get the perfect balance of drying and moisture retention.
As a groundskeeper, think of the various types of infield soil topdressing materials as tools in your toolbox. Depending on the climate in your area, adjust the make-up of your topdressing to get the results you want in order to manage the moisture in your infield skin. You can go with the same topdressing all year long or, if your budget allows, you can adjust the make-up of your infield skin topdressing depending on the season of the year and how it affects the moisture in your fields. If you talk to the professionals at the collegiate and pro levels, many will tell you that they typically use a blend of two types of topdressing materials. They craft their infields to perform exactly the way they want it to by fine tuning the ratio of the two products on their surface.
The bottom line is that topdressings on the surface of your infield skin make management of that skin much easier. Infield skin topdressings improve the playability and resiliency for the ballplayer. Just make sure you are properly managing that layer so you don’t bury it into the base soil beneath it.