Winter Education Vol. 2 - Engineered Soil Technology - Silt to Clay Ratio

Engineered Soil Technology - Originally posted in January 2010.

As the Head Groundskeeper at Victory Field, I can’t tell you how many times I heard this saying. “Well we don’t have the budget that you do at Victory Field!” Of course, most facilities do not have the budget of a professional facility. So, my goal was, how do we bring the materials that are used at the highest levels and apply them to all fields. Engineered Soil Technology  (EST) is the answer.

A properly balanced infield mix after play - cleat in-cleat out

EST is the process that computer blends materials. So, with the advent of EST, engineered soil manufacturers can computer blend amendments and mixes based on your field needs. In the past, what was used at Victory Field would not work at a city park. The lower sand content and higher clay content of the professional mixes become too difficult to manage for a parks system that has 1 person working on 5 fields. That’s a long way from the 8 I had working on the playing surface at Victory Field after games. 

Now, with EST the same manufacturer can blend a mix that has 60% sand, typical in a professional setting, and also blend a mix that has 72% sand, typical with a recreational setting. Both mixes contain the same raw material/mineral - silt and clay, with the overall sand content adjusted for the level of play. Thus, the technology  and materials that are used at the highest levels is now brought to all levels, adjusted to ratios that are manageable to the grounds crew and coaching staffs. How cool is that!

Another acronym that will become commonplace in the sports turf industry is SCR. SCR stands for silt to clay ratio. How do you figure out your SCR? Simply divide your silt by your clay. 

For example: A mix contains 70% sand, 22% silt, and 8% clay.

The SCR is 22 divided by 8 = 2.75 SCR

As a rule of thumb, your SCR should be .5 – 1.0. What happens if your SCR is above 1.0? Your infield will be sloppy in the spring (i.e. the material pushes out of each side of your shoes as the step on a wet infield).

How about, low areas around your bases and a dusty infield when dry? Without even looking at the infield, I would bet that the SCR is greater than 2.5. 

Most mixes native to Indiana do have an SCR of 2.5 or higher. What does that mean for your infield? If your SCR is 2.5+ it will play well in some but not all conditions. In other words, you will be re-scheduling games while those with an SCR of 1.0 will be playing.

Do you test your infield soil? What is your SCR? Why head into the 2014 season not knowing?

Play on!
--Jamie

@JamieMehringer