5 Simple Principles That Can Make Anyone a Sand-Silt-Clay Ratio Expert
PUBLISHED ON JANUARY 11, 2019
By Sports Field Solutions
How to Give Your Team a Field that will Help Them Win
Why does it have to get more complicated than that?
Because your players deserve better than that. They deserve the best playing surface you can give them, and to achieve that, you need to think about the sand-silt-clay ratio of your baseball field.
If you want a good infield mix that will benefit your team, you need to know what goes into it.
Lucky for you, sand-silt-clay ratios are easy to understand. We’ve summarized everything you need to know in 5 principles that will transform you a into sand-silt-clay pro.
Let’s get the ball rolling with principle #1.
1. How Your Field Withstands Rainstorms
Sand, silt, and clay are the 3 main components of your infield, so in order to understand the “why” behind the ratios, you need to know a little more about soil mechanics.
We’re gonna start with the biggest particle: sand.
Sand particles are between 0.05 and 2.0mm wide. Because of their size, water flows right through them.
Think of it like this:
Imagine you have a ball storage locker full of basketballs. 25 basketballs fit in the locker, but there’s still a lot of empty space between the basketballs.
Sand works the same way. Because of the immensity of the particles, there’s a great deal of “empty space” around them. Water flows easily through the gaps. For this reason, sand is considered to be porous, or to have a high porosity.
Well, by choosing a medium or coarse sand, you can ensure stability on your field. When rain pours down in the middle of a game, the water will flow through the sand and won’t disrupt the playing surface.
Sand on a beach is a great example of this stability. The wet sand at the edge of the water is sturdy, which is exactly how you want your field on a rainy day. Without sand, your field would become a sticky, muddy nightmare. You don’t want to stop the game because of a little rain, do you?
2. Why Your Infield Is a Dusty Mess
Now let’s talk about silt.
Remember our basketball storage locker?
Imagine that instead of basketballs, you have baseballs in the same locker.
You can fit WAY more baseballs inside the locker, and the amount of empty space decreases significantly. These baseballs represent silt, which is smaller than sand (0.002-0.05mm). For this reason, silt has a medium porosity. Water trickles through the gaps, but not as easily as sand.
Silt basically acts as a binding agent between sand and clay. When it’s dry, it becomes floury and dusty, and when it’s wet, it becomes slippery. If your field gets extremely dusty, you could have too much silt.
3. How to Prevent a Cracked, Rock-hard Infield
Now we can move on to the last type of sediment in the ratio: clay.
The spectacular scarlet color of your baseball field comes from clay. The particles are less than 0.002mm in diameter, making it the smallest particle in the mix.
Let’s use the ball storage locker analogy (don’t worry, this is the last time):
This time, your locker is filled with mini-frisbees. They stack on top of each other without any space between. You could fit over three hundred in the locker.
If clay is like these thin baby frisbees, do you think water flows through the particles?
Not only is there zero empty space, but the clay plates are also negatively charged. Water has 2 hydrogen atoms that are positively charged. You know what they say: opposites attract. Clay and water snap together like magnets.
Why is this magic clay-water interaction important?
Water sticks to clay. This means that clay retains moisture like crazy. It has a low porosity and holds more water than sand and silt.
Want to prevent your field from drying out?
Increase water retention by increasing the amount of clay in your dirt ratio.
But wait: there’s a downside.
If you’ve ever stepped on a cracking, unyielding infield, you already know what we’re talking about.
Clay has plastic qualities. When clay gets wet, the tiny water molecules sneak between the plates and stick to them, causing the clay to expand. When the clay dries, it shrinks, leaving your fieldhard, cracked, and brittle. The next time it rains, water drips into the cracks and wets that clay more than the rest. The result? An uneven, cracked playing surface.
To prevent this from occurring, you need to prevent your field from drying out and water it down frequently. If you don’t have the means to water it, you need to lower the amount of clay in your infield dirt.
How much clay is ideal?
To answer that, we need to move on to principle #4.
4. What You Need to Know about SCR
SCR stands for silt-to-clay ratio. This is an easy calculation that can help you to determine the state of your field.
All you have to do is divide the percentage of silt by the percentage of clay. As a general rule, an SCR between 0.5-1 is good, 1.0-2.0 needs improvement, and >2.0 is bad.
Don’t panic yet. An SCR over 2.0 doesn’t mean your field is unplayable. All it means is that your percentages aren’t ideal, and if you fixed them, your players would have a much easier time playing on your field.
This is easier to understand with examples:
You’re the athletic director of a university with a high-end baseball field. Your infield is 60% sand, 20% clay, and 20% silt.
To find your SCR, divide 20% silt by 20% clay.
20/20=1. You have an SCR of 1. (Which means your field is perfect!)
You have a high school baseball field with 64% sand, 24% silt, and 12% clay.
To find your SCR, divide 24% silt by 12% clay.
24/12=2. An SCR of 2.0 is not in the ideal range.
You should add clay and remove silt from your infield (18% silt and 18% clay would make your SCR=1).
Even recreational level fields with irregular maintenance can have a good SCR. Maybe you have a high percentage of sand, but you can still adjust the percentage of your silt and clay to keep your SCR between 0.5 and 1.0.
5. How to Apply This to Your Field (Based on National Statistics)
Obviously a Major League field is different than a city recreational field. Your perfect sand-silt-clay ratio depends on your budget, time, and staff capabilities.
That being said, we’re going to give some rough estimates of optimal sand-silt-clay ratios depending on the type of field you have. Remember that these are only estimates; your field could need very different percentages depending on your budget, use, and climate.
You have constant access to water and you have several employees for daily field maintenance. This category includes professional teams and division one colleges.
Silt and clay: 38-42%
You have constant access to water, but limited maintenance. Colleges, high schools, and sports complexes fall into this category.
Silt and clay: 32-35%
You have no access to water and irregular maintenance. This category consists of school and park fields.
Silt and clay: 25-30%
Notice that less maintenance and less water = less clay (because of the plastic qualities of clay that we mentioned above). Without proper maintenance, clay cracks and hardens.
Also notice the recommended SCR of all the fields: 0.5-1.0. It doesn’t matter if you have 75% sand, you need to keep your SCR between 0.5-1.0.
Obviously these optimal ranges are the perfect goal, but real-life fields aren’t perfect. For reference, here’s a chart with the real-life average sand-silt-clay ratios for different levels of fields:
What’s Your Excuse Now?
These 5 principles aren’t rocket science. They’re simple and straightforward. Yet if you apply this knowledge to your infield, you can WOW your players, coaches, and alumni. Give them what they want—a soft, sturdy, beautiful field that helps them stay safe, have fun, and win.