A close-up, turf-level view of the field after laser grading.
PHOTOS COURTESY OF J&D TURF
The safest bet for a good start in the spring is getting your baseball and softball infield surfaces prepped in the fall. Weather is typically drier and more predictable than spring, and there’s no pressure for early play. Timing will depend on your field use schedules, with the window from when fall play ends until winter conditions move in, typically from mid-September to the end of October.
With good field construction and an effective in-season maintenance program, postseason maintenance consists of a few basic steps performed annually with a more aggressive renovation added in a two to three-year rotation. The major segment of the renovation process is incorporating additional materials into the existing infield to re-establish the original finish grade level and to ensure correct surface drainage and good ball roll.
Start right for renovation
Building and maintaining baseball and softball infields has been considered an art, a subjective process based on the opinion of the sports field manager. When the process is a science, based on soil tests, the results can be predictable and replicable. The object is a good infield mix with three major characteristics: traction, playability and consistency. It should play consistently in a variety of weather conditions with sufficient traction to allow the athletes to play the game without slipping.
J&D Turf laser grades a field.
The first component of the infield is the base of compacted native soil, 3 to 6 inches below the surface. I’ve found subsurface drainage below the skinned material to be ineffective in most cases and, if drainage tiles sink or rise over time, detrimental or downright dangerous. Proper and consistent slope across the surface will provide adequate drainage once a good, balanced infield material is in place.
All three components of the infield mix – sand, silt and clay – play a role. Sand, the largest size soil particle, provides the structural integrity. The targeted range within the mix is 58 to 75 percent. Silt, the second largest soil particle, acts as a bridge between the sand and the clay, with 10 to 35 percent the acceptable range. Clay, the smallest soil particle, provides the color of the mix and retains moisture; 15 to 35 percent is the acceptable range.
Typically, a parks and recreation or high school infield mix will contain about 72 percent sand, a college field around 65 percent and a professional field 60 percent or lower. At 60 percent sand, the mix retains more moisture, providing a firmer surface for good cleat in, cleat out contact with minimal tearing. Though it plays well, maintaining the right degree of moisture with the low percentage of sand is a time-intensive process. A mix with a higher sand content will tear up more, but the reduced time required for moisture maintenance better fits the limited staffing of most municipal fields.
The new infield mix is applied evenly across the infield surface.
Two factors, in terms of playability, are more critical than the sand percentage. The first is the sizing of the sand. Over 50 percent should be retained on the medium sieve for recreational mixes. The second is the silt/clay ratio (SCR). This should be in the range of .75 to 1.To find your SCR, divide the percentage of silt by the percentage of clay.
The first step in achieving a balanced infield mix is testing. Through the process of Engineered Soil Technology (EST) suppliers blend custom amendments and mixes based on the specific needs of your field. To get a clean sample for testing and/or to prepare the surface before the renovation process begins, remove the topdressing material of calcined or vitrified clay or crushed aggregate. Use the scraper edge of a landscape rake to windrow the material and scoop it off with a shovel. Clean material, free of the existing mix, can be stockpiled for reuse on the infield. Discard material contaminated with the mix. Pull the infield sample and submit it to a qualified lab for testing.
The FieldSaver is loaded for spreading.
Many natural mixes have a high SCR. A mix of 70 percent sand, 22 percent silt and 8 percent clay has an SCR of 2.75 (22 divided by 8 = 2.75). It will become mucky and sloppy when wet, and play firm and very dusty when dry. The addition of an engineered soil, based on testing data, will increase the percentage of clay, bringing the SCR of the augmented mix closer to 1.0 and more consistent playability.
When test results show that an infield mix will benefit from the addition of clay, be sure to stipulate/use a natural clay. The high-heat process used to create calcined or vitrified clay changes the structure so that it no longer acts like natural clay. When tilled into the infield mix, it produces results similar to increasing the percentage of coarse sand and/or gravel.
Using a BLECavator on the baseline produces these results.
Prior to bringing in the new infield material, reestablish your base line edges and address any lip issues. Verify the correct dimensions for the field’s level of play and run string lines to ensure accuracy. To clear out the encroaching grasses and reset the level back to finish grade, you’ll need a bed edger, a typical blade edger and a loop hoe. Add a sod cutter if major measurement adjustments are needed. This process may lower the difference in measurement between the turf and infield material significantly, reducing the amount of new infield mix you’ll need. Once the edges are reestablished, create a map of your field with all the dimensions noted and keep it in your office. You’ll want to end each fall season and start the spring season by edging the field to match that map.
If the material application and grading work will be done by an outside contractor, make sure they are skilled in laser technology and discuss their overall plan to ensure it will meet your expectations before the project begins.
Check your infield for grade issues. If the grade is poor, have a rough laser grade performed to move the existing mix into the correct location so you will have consistency in the depth of the new material applied. Use a topdresser to spread the new mix evenly across the prepared surface.
Blend, level and roll
Once the new mix is spread, blend it into the existing material, working it to a 3 to 4-inch depth. Equipment such as a BLECavator or a Rotadairon is the best option to achieve thorough blending. While the work can be done with a tiller, it will take more time. Use a hand tiller to work all the edges and the baselines. Make sure you’re reaching deep enough into the existing material so the resulting blend matches the consistency of the rest of the renovated mix. When all the material has been blended, compact it with a 3-ton roller.
The next step is precision laser-grading to establish surface drainage. On a baseball infield, a .5 percent grade from the front edge to the back arc is all that is needed. For a softball infield, establish a .4 percent grade from the pitching rubber in all directions. Any grade greater than .4 percent will create the appearance of a mound. Continue that .4 percent grade all the way to the dugouts and backstop. Increasing the degree of slope at the foul lines will result in runoff into the dugouts and backstop areas during heavy rains.
Accuracy and consistency are essential when laser grading. Use the grade and roll method, with the 3-ton roller following the grader to pack the material firm and tight and continually adjusting during the process to ensure precision. Even small variations can cause drainage problems.
Once the laser leveling is completed, put down the 1/8 to .25-inch topdressing of conditioner and flood with water to complete the process, or do the watering and apply the conditioner a few weeks later, followed by another flooding. Whichever you choose, you want that mix tightly locked together and packed down for the winter.
Postseason every year
Re-establish your edges during annual postseason maintenance, even when no additional infield mix is needed. I recommend laser grading the infield too. The rest of the postseason infield process is the same every year. Continue to edge to control lips. Drag regularly to ensure a smooth surface and control weeds. Keep topdressing at your typical levels.
Prior to the weather-related shutdown of maintenance, take steps to reduce winter migration of materials. Put down a skin tarp, use a silt fence or dig a small trench along the back edge of the base path.
In a perfect world, before the first player steps on the field, you’ll use your map of dimensions to string line your measurements and re-establish your edges; replace any material reduced by migration; and use a 3-ton roller to settle the infield after winter’s freeze-thaw cycles to retain the established grade.
To determine when to roll, test the surface by walking across your infield mix. It should settle under your foot and there should be no material sticking to the bottom of your shoe as you walk off. You want a little moisture in the mix, so a bit of “give” is OK; lateral movement to the point of material oozing is too wet.
The choice of calcined or vitrified clay or crushed aggregate, and the depth of the topdressing layer within that 1/8 to .25-inch range, will depend on your playing conditions and the labor and budget resources you have for maintenance. Apply topdressing to reach playing depth and do a light nail drag – .25-inch is good. Follow that with a mat drag. I prefer a rigid mat drag because it won’t roll over high areas or dig deeper into low areas, and it provides minor leveling as well as smoothing the infield surface.
FieldSaver has been added to the existing material; this view shows the results of one pass with the BLECavator.
If your infield mix is balanced and properly graded for drainage, and your spring start-up has all components in place for play, the in-season maintenance is pretty basic. Prior to each practice or game: tire roll all position areas and the areas around bases; nail drag to a depth no greater than .25 inch; hand rake all the edges with a landscape rake; mat drag; and water.
After every practice or game: hand rake all position areas and areas around the bases; mat drag; hand rake all edges with a landscape rake; roll with a 1 to 1.5-ton roller; flood the infield to the point of standing water.
As needed in-season: add conditioner to maintain your chosen level, float conditioner and add infield mix. Keep lips from forming by using a tine rake, broom or blast of water to remove infill material from the turf. Edge the infield with a blade edger a minimum of every two weeks, string lining the edges for accuracy every time. If you follow this schedule, you won’t need the last resort – taking a sod cutter to trim back the sod, removing built-up material with a rake, and replacing the sod.
Jamie Mehringer is president of J&D Turf, a sports field consulting, construction, maintenance and distribution company, based in Indianapolis, Ind.