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Here in the north, winter time provides a chance to assess the previous season, take a “deep breath,” and to plan for the following year. For facility managers, administrators, and volunteer board members now is the time to designate improvements which must be made to your facility.

Planning your field renovation projects months ahead of time will streamline the process and ensure you receive the best possible product. Some projects are required annually, and are easy to plan for – spring aerification on a football-specific field, for example. Larger projects such as total renovation of a baseball infield occur less frequently but should be anticipated every few seasons.

Infield renovations on baseball and softball surfaces are best accomplished in the summer and fall months, instead of the early spring before or during the season. Let’s review a few reasons why this is the case:

  • Wet field conditions: Many believe that an infield can be worked on as soon as the snow melts. Unfortunately, this is a false sign of spring with regard to field renovations. Sports fields should not be worked on (or walked on!) until all the frost has thawed. Even once the deep frost is gone, the ground surface may freeze over cold nights and thaw out under the strong April sun, only to freeze again the following evening. These freeze-thaw cycles make the ground very soft during daytime hours, so equipment such as laser-grading tractors, utility carts, and topdressers cannot be driven on the infield without getting stuck (Fig. 1). Trucks hauling material onto the field will either sink or leave damaging ruts behind.
H & K Sports Fields Maintenance

Figure 1: Wet field conditions often delay spring infield work, even once the ground has thawed, Equipment cannot be driven on the field without making a mess of the surface.

H & K Sports Fields Field Maintenance

If the field is not firm enough to walk on, it should not be played on and certainly cannot be tiled and laser graded.

  • Rushed timelines: The spring baseball and softball seasons are extremely short in Wisconsin. High school and college seasons are jammed into less than two months. Because the project must be crammed between field usages, the work tends to be rushed and of lesser quality than that done during a down period on the field. With games and practices occurring almost daily it is impossible to renovate an infield and allow ample time for the soil to settle before play resumes. After a field is tilled and re-graded, the soil tends to be quite loose until a few wetting and drying cycles have occurred to “firm it up.” Playing on a freshly graded infield skin can quickly create low spots in the high-traffic portions of the field, compromising the newly established grade.

 

  • Soil production: Soil suppliers also battle wet conditions in the spring. In order to shred and blend products such as infield mix (Fig. 2), the suppliers must first harvest the raw materials from a field or a large outdoor stockpile. When the raw soil is in a sticky, plastic condition, no production can occur because the material will not flow through pulverizing and screening equipment. So even when the conditions at your facility are acceptable for earthmoving, if material suppliers are out of commission the project must be delayed. During the summer and fall, warm temperatures allow for quick evaporation and a speedy return to production after rain. In addition, some suppliers are able to get ahead of demand and maintain covered stockpiles as an insurance policy.
H & K Sports Fields field renovation

Figure 2: Weather conditions must be dry for soil suppliers to handle, screen, and blend materials. Although finished stockpiles can be covered it is usually impractical to keep the raw components shielded from the elements.

  • Sod availability: Like soil suppliers, sod growers are subject to Mother Nature’s authority. In order to harvest rolls of turf the ground must be firm enough to support heavy equipment (Fig. 3). In Wisconsin this typically occurs in early May. Level fields are intentionally chosen for sod production but certainly are not graded with the precision of a sports field, so drainage can be somewhat slower. Fall is the best time of year to harvest and install sod. The ground is firm and the weather is very favorable for cool-season turf grasses, so the new sod will quickly take root.
H & K Sports Fields - sod production fields must maintenance

Figure 3: Sod production fields must be dry to support the weight of harvesting equipment and delivery trucks.

H & K Sports Fields - sod production field harvesting equipment

Field renovation projects can still be completed in the springtime – but summer and autumn are the ideal windows for laser grading and other extensive work on your baseball and softball fields. We encourage our clients to plan ahead and book services for the summer and fall months now as our schedule tends to fill up quickly once spring hits. We hope this winter you catch some needed rest and find the time to plan for another successful season!

Check out other editions of the H&K Maintenance Minute for simple tips to help your field sparkle at www.hksportsfields.com

For most of the past 150 years, baseball groundskeepers literally “leveled the playing field” by using string lines, wheelbarrows, and hand tools. A smooth playing surface with the correct slope ensures true hops for the players and also allows water to run off the field. Manual leveling of an infield is still effective, but this process is slow, labor-intensive, and not practical for most parks and schools. Fortunately, laser grading now provides a rapid and highly exact solution to infield drainage problems.

 

Many folks we work with complain that their infield will not drain (Figure 1). I like to politely remind them that infield soils are not designed to “drain,” at least not in the vertical sense. A quality infield soil contains too much silt and clay to transmit water down through the profile. Instead, water must flow off the surface by following gravity- this is where laser grading comes in.

Figure 1. Infield skin areas are not designed to have excess water percolate through the soil. Standing water on this infield should be addressed by adding infield mix and laser grading.

Figure 1. Infield skin areas are not designed to have excess water percolate through the soil. Standing water on this infield should be addressed by adding infield mix and laser grading.

In order to guarantee surface drainage from the infield, two conditions are required:

  • Sufficient elevation change from the high point to low point
  • A smooth surface without high spots or dips, which can impede surface flow

 

Proper laser grading satisfies both these conditions. The basic idea is that a tractor towing a laser-guided box blade is driven over the field, cutting high spots and filling depressions until the infield exactly conforms to the desired slope. If used properly, the laser guided blade is much more precise than the human eye, hence the title of this article. The nuts and bolts of this process are far from rocket science, but do require some thought and careful operation.

Here’s how it works: first, our crew conducts a survey of the field’s existing elevations to determine which type of laser to use. A rotary laser is a device which projects a beam of light while spinning at several rotations per second. The light beam can be detected by a receiver and rod marked in inches or feet (Fig. 2). Once the survey is done, we decide whether to use a cone laser or a dual-slope laser to grade the field.

Figure 2. Rotary laser (left) and laser detector mounted to rod marked with inches and fractions (right).

Figure 2. Rotary laser (left) and laser detector mounted to rod marked with inches and fractions (right).

The preferred grading plan for baseball and softball fields uses a cone laser. This laser is placed at the center of the field, from where it projects an invisible cone extending in all directions. (Figure 3). The slope can be set to any desired value. This field design allows water to travel the shortest possible distance before exiting the skin.

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Figure 3. Top: Infield graded with cone laser, showing equal slope in all directions. Bottom: cross section of field (not to scale) showing linear distances and vertical elevation changes.

Figure 3. Top: Infield graded with cone laser, showing equal slope in all directions. Bottom: cross section of field (not to scale) showing linear distances and vertical elevation changes.

Occasionally a field will have its high point in the center, but with different elevations along the grass edges. If this type of field were to be laser graded as a symmetrical cone, the infield skin will not conform or “tie in” to the existing grass edges. However, as long as the center of the field is the highest point, the projected cone can be tilted slightly to “split the difference” between the two slopes (Figure 4). This grading plan works well when the existing field contours are similar to a cone but need a slight adjustment. The example in Figure 4 shows a field where the right side is lower than the center but higher than the left side. In this case the slope on the cone laser would be set to 0.75% (the average of 1% and 0.5%) and its axis tilted toward the left side of the diagram. This produces a “true slope” which conforms to both sides of the field.

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Figure 4. Top: Infield graded with tilted cone laser. Center of field is highest point with slope in all directions. Length of arrows denotes degree of slope in each direction. Bottom: cross section of field (not to scale) showing linear distances and vertical elevation changes. Vertical arrow from laser indicates a standard cone setup; angled axis indicates tilt required to achieve conformity with existing grass elevations.

Often times, the field was not built by a sports field-specific contractor Many general contractors simply construct skinned infields with the “lay of the land;” that is, sloped from one side of the field to the other. This is called sheet draining. Sheet draining is the least preferred grading method because water must travel the furthest distance across the skin. A cone laser cannot be used on this type of field without total reconstruction of the sidelines and a portion of the outfield.

 

Fortunately this situation does not preclude the use of laser grading: enter the dual-slope laser. Rather than a cone shape, a dual-slope laser projects a plane which can be rotated to create any desired 3-dimensional orientation. It is called a dual-slope laser because it has two axes (slopes), both of which are adjustable. To visualize how this laser works, pick up a notecard or a piece of paper with both hands. First raise and lower you right hand. This simulates adjusting the x-axis of the dual-slope laser. Now rotate the paper away from your body- this simulates adjusting the y-axis. By setting both these to the proper values, the laser creates a plane which will conform to the existing sheet drain.

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Figure 5.Top: Infield graded with dual slope laser, showing sheet-drain grading plan. Bottom: cross section of field (not to scale) showing linear distances and vertical elevation changes.

Figure 5.Top: Infield graded with dual slope laser, showing sheet-drain grading plan. Bottom: cross section of field (not to scale) showing linear distances and vertical elevation changes.

 

A dual slope laser can also be used to “parcel” a field into smaller sections. This grading plan works well when home plate is the high point. An example is shown in Fig. 6: the field is split in half. Starting at home plate, there is downward slope both toward center field and also toward 1st and 3rd bases. To visualize how the laser projects this grading plan, examine the cross section in Fig. 6. Hold your pencil horizontally with the tip touching the high point in the diagram. Now raise the eraser without moving the tip. The pencil depicts the y-axis while the x-axis can be oriented to match the left or right half of the field. This type of field requires water to travel further than a cone-graded field, but it is still an improvement over the sheet-drain type field because the water has less distance to travel before reaching the grass.

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Figure 6. Top: Infield graded with dual slope laser, showing split sheet-drain grading plan. Bottom: cross section of field (not to scale) showing linear distances and vertical elevation changes.

Once the laser is set to the desired slope, a receiver is mounted to the mast on our tractor. This receiver communicates with the laser to raise and lower the grading box, cutting and filling soil as needed. Figure 7 illustrates this process. After grading, the infield will exactly mirror the invisible surface produced by the laser ~8 feet above it.

 

Even with a cone or dual-slope laser set up properly, it is rare for an existing field at a public park or school to have grass edges which tie in perfectly to the laser’s shape. This is why laser grading is not “idiot-proof,” as some in the industry believe. Like all computers, the laser-guided equipment can’t think for itself. The laser grading box will do exactly what it is told, even if the directions are wrong! Therefore the equipment is only as useful as the person telling it what to do. If left on automatic mode near the edges, the box blade will usually try to either cut the skin below the grass level or leave a sharp drop-off from the skin over the last few feet. After laser grading 95% of the field, the operator must manually over-ride the computer at the end of the grading process in order to taper the skin down to the grass and create a smooth transition. This ensures good drainage and player safety.

 

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Figure 7. Operation of laser-guided grading blade. The electronic controls raise and lower the box as needed. The computer keeps the distance from the laser beam to the ground surface constant despite the contours of the uneven ground.

 

Does your infield collect water after a rain? Do surface undulations reduce playability and cause bad hops? Has the skin developed high and low areas from dragging and field usage? These are signs your infield would benefit from laser grading. Contact us for a free site assessment- we can provide the laser-grading solution for your field. Remember, the laser doesn’t lie!

H&K Sports Fields

 

Dragging

Dragging is the most basic task in maintenance of a baseball or softball field. It is usually the first thing done to the field after a game or practice. Proper dragging procedures can make or break the quality of your infield. In this article we take a closer look at a seemingly simple task.
1. Why we drag

First, let’s review why we drag the infield. During games and practices the players disturb the soil, creating divots and cleat marks while leaving clods of soil behind. These clods are unsightly and can contribute to bad hops. If it rains before the field is dragged to break up the clods and re-distribute the soil, the clods can “melt” and later harden, leaving a bumpy, uneven surface. Dragging breaks down lumps of soil to smooth the surface (Figure 1). After a field is dragged, it is uniform and visually appealing. So we drag the infield for both functional and aesthetic reasons. It is worth noting that while dragging intentionally disrupts the surface, our goal is to move as little soil as possible. This helps preserve the surface grade. During routine maintenance your goal is to groom the material without pulling it from place to place.

H&K Sorts Field grooming the field

Figure 1: Dragging provides both functional benefits such as consistent ball response, and aesthetic benefits such as a smooth, uniform surface.

2. Types of drags
There are three main types of drags: screen drags, nail drags, and finish drags. Each tool has a different purpose and should be used at the proper moisture content.

A screen drag is the “bread and butter” of your infield maintenance tool arsenal. This drag abrades the soil clods, filling in cleat marks and other depressions. It should be used when the soil is reasonably dry and has a friable consistency (Figure 2). If a topdressing layer such as Magic Mix or calcined clay is present, the screen drag interacts mostly with the topdressing material. Screen dragging helps to keep the granular topdressing separated from the base soil below.

A screen drag should be used after every game or practice. Screen drags come in a variety of sizes and configurations; the largest types tend to sling more material when turning, so avoid using very large or heavy screen drags. Some screen drags are fitted with a leveling bar in front (Figure 3). This helps even out the soil before it is abraded by the metal screen.

H&K Sports Fields

Figure 2: Chunks of soil left on the field after a game. A screen drag should be used to smooth the surface. The bases should always be removed and replaced with foam plugs before dragging

 

H&K Sports Field screen drag

Figure 3: A screen drag being towed behind a utility vehicle. The angled leveling bar in front helps knock down high spots and fill depressions before the soil is smoothed by the galvanized mesh. (Image credit: Beacon Athletics)

 

A nail drag is a very valuable tool for maintain your infield, but it must be used with great caution. The main reason for nail dragging is to cut down small undulations, permitting the looser material to be smoothed out by a subsequent pass with a screen drag. The drag should never penetrate more than ¼-½” deep. Check the consistency by inserting a key into the ground- if the soil offers some resistance but the key penetrates it and comes out clean, the moisture is perfect for nail dragging. Scarifying too deeply or at too high a moisture content can damage your infield in a hurry. Nail dragging too deeply will create a loose, dusty surface once the material dries (Figure 4). The loose soil is easily displaced during play or by the elements and creates high and low spots on the infield. Some of the soil migrates into the grass edges where it forms a lip. Once it is overly loosened, the infield must be watered and then rolled to firm it up again. Opening the skin up before a rain will permit more of the water to soak in, rather than running off the surface, so avoid this practice.

H&K Sports Fields a dusty infield

Figure 4: A dusty infield produced by the combination of poor-quality material and excessive nail dragging. Note the footprints in the dry material; when wet this field will become very messy.

 

A common misconception is that nail dragging a wet field repeatedly will help dry it out. Infield drying is mostly governed by the weather conditions- temperature, humidity, wind, and sun. If the field is firm enough to walk on, cautiously nail dragging your field one time will help expose more surface area to the air and speed up the drying process. But nail dragging repeatedly will only mix the dry material on top with the wetter soil below, actually slowing the drying rate. If the infield is not firm enough to walk on without creating footprint impressions, stay off the field!! Figure 5 demonstrates such a scenario. It is very tempting to try to dry the field out – every seasoned groundskeeper has learned this lesson the hard way. The best solution is to do nothing until the field has dried enough to firmly support foot traffic.

 

H&K Sports Fields

Figure 5: This infield is too wet to play or work on. Soil did not stick to this person’s shoes because of the granular topdressing layer, but players with cleats will quickly wreak havoc on this field. In addition the footing would be poor, exposing the players to a risk of injury. Nail dragging this field would only draw moisture to the surface, compounding the problem. The field must be given time to dry before it is worked on. Using a soil with the proper balance of sand, silt, and clay would also help this field remain firm after a rain.

 

Excessive nail dragging also contributes to “sinking” of topdressing material, creating a need to purchase and apply additional material. The tines of a nail drag should never be wider than 1/4” which is the size of a 40d (“40-penny”) common nail. Bolts should not be used to construct a nail drag- they are too aggressive and their flat bottoms tend to create more surface disruption than the clean incisions produced by a sharp nail (Figure 6).

H&K Sports Fields Proper Nail Drag

Figure 6a: Proper nail drag construction using 40d common nails

 

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Figure 6b: Improper construction using ½” zinc hex bolts. This drag is much too aggressive and will produce a washboard pattern on the infield.

 

The third drag category is finish drags. This tool can be used to remove any windrows or lines remaining after screen dragging. Examples include cocoa mat drags and tennis court brooms (Figure 7). The main job of these drags is purely aesthetic, as they put a beautifully groomed finish to the field. There is one exception to this rule; when the field is wet and quickly clogs your screen drag, a cocoa mat drag can be used to float over the surface, though this process does little to actually level the soil.

H&K Sports Fields Finish Drags

Figure 7a: Finish drags will not leave windrows or lines on their edges and can be used to leave the skin looking perfectly uniform. (Image credit: Beacon Athletics)

 

H&K Sports Fields Cocoa Mat

Figure 7b: A cocoa mat drag also works well when the field is too wet to screen drag. (Image credit: Beacon Athletics)

3. Methods of dragging and common mistakes

Before dragging, remove the bases and cap the anchors with foam plugs. You can now drag directly over the anchors without filling them with soil. If the bases are left in, high spots will develop as the drag deposits soil next to them. All dragging procedures should be conducted in alternating directions. When a “zamboni” style pattern is used one day, drag in circles the next day (Figure 8). Sometimes more than one pass is needed with a screen drag to completely smooth the surface. In this case be sure to go in a perpendicular direction with the second pass. On an all-skin softball field, resist the temptation to start in the center of the field and work outward. This is the number one cause of “bowled out” fields, which develop a large lip along the outfield perimeter and collect standing water in the center. On an all-skin field either begin at the outside and work inward, or use a zamboni pattern across the whole field, changing your direction each day.

 

H&K Sports Fields Recommended dragging patterns

Figure 8: Recommended dragging patterns. Alternate between these patterns to avoid creating high and low spots on the field. If time allows, perform both patterns when you drag. (Image credit: DiamondTex)

 

Be sure to stay at least a foot away from the grass when dragging (Figure 9). This sounds like an easy rule to follow, but every groundskeeper has been guilty of violating it at some point. This is just plain lazy. Get off the vehicle and hand rake the edges to avoid dragging soil into the grass. Edge maintenance is already the biggest pain in a groundskeeper’s side, so we have avoid making more work for yourself later.

 

The most widespread dragging error is excessive ground speed. We can’t overstate the importance of going S-L-O-W!! The pace of dragging, even with a vehicle, should be no faster than a brisk walk. Yes, you have 4 more fields to drag, yes it can be boring, but you must not drag your field at a high speed. This process alone can be responsible for destroying a perfectly graded infield skin in a single season. Fast dragging slings soil around the field and creates a wavy pattern in the soil. It’s also imperative that the correct drag is chosen to match the soil moisture. This can only be learned through experience.

 

H&K Sports Fields Dragging the infield

Figure 9a: When dragging the infield always stay at least a foot away from the grass. This rule applies whether the drag is being pulled by a vehicle or by hand. Even when caution is used, a screen drag can create windrows of topdressing on either side, which are easily kicked or washed into the grass.

 

H&K Sports Fields Hand Raking field adjacent to grass

Figure 9b: Use a hand rake to carefully smooth the soil adjacent to the grass.

 

Conclusions

Dragging your infield with the correct tools, in the correct manner, at the correct time will ensure your infield stays safe, playable, and beautiful for several seasons. Alternate directions, go slowly, stay away from the edges, and keep off the field if it is too wet. Check out other installments of the H&K Maintenance Minute on our website, where we examine other field management tips to help your facility sparkle. Happy dragging!

H&K Sports Fields - Better Fields Make Better Players

H&K Sports Fields – Better Fields Make Better Players

Managing Field Hardness

 

Player safety is touted by sports field managers as their first priority. Player injuries can be acute or chronic; respective examples would be spraining an ankle vs. shin splints. The chance for both types of injuries is increased by a surface which is too hard.

Surface hardness is the amount of energy returned to an object (a ball, or part of an athlete’s body) when it strikes the ground. Hardness is measured in Gmax, a unit which describes how quickly an object decelerates on impact. You can visualize this deceleration measurement in terms of extremes- if you jump onto a soft couch, you will land gradually because the cushion will absorb most of your kinetic energy. On the other hand, if you dive onto a tile floor, your downward motion will be stopped very quickly since the floor returns most of the energy to your body (ouch!). The standard device for measuring Gmax on natural grass sports fields is the Clegg Impact Hammer. This device is easy to use and can be purchased by facility managers who wish to monitor field hardness. High Gmax on a sports field can lead to injuries. In the NFL’s field testing program, all fields must register below 100 Gmax to be considered safe.

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The second variable in field hardness is soil water content. On fields with irrigation, soil moisture can be somewhat controlled. On non-irrigated fields, the soil becomes harder as it dries out. By increasing the soil’s pore space with aeration and compost topdressing, more water will infiltrate during rain events and will remain in the soil during dry spells.

You may be surprised that we didn’t name the grass itself as a variable affecting field hardness. Indeed, the grass plants on their own don’t play a big role, but their influence on the soil is very important. Simply maintaining good turf cover goes a long way toward keeping field hardness at the right level. Bare soil is more apt to dry out and become hard. A great example is a baseball or softball field on the day following a rain. The skin portion of the field will usually dry out quickly and become very hard unless more water is applied. Conversely, the grass areas will retain some moisture and have a more forgiving feel underfoot. This is because the grass shields the soil from the sun and reduces evaporation. Practices which encourage healthy grass- such as frequent mowing, a cutting height between 2-3,” and adequate fertilization- will help minimize surface hardness by maintaining the turf cover.

field-evaoporation

Natural grass and synthetic turf fields will both become harder over time without proper maintenance. The reasons for each field type’s increased hardness are different.

On a natural grass field, hardness is mostly related to the soil underneath- namely, the compaction level and the moisture content. It is intuitive to most people that compacted soil is harder. This can be explained by soil science, too. On a microscopic level, the soil particles in a compacted field are so close together that they can’t be displaced very easily, and they don’t dissipate much energy. Soil compaction can be relieved with core aeration, which should be performed several times per year on a high-traffic field. An excellent way to reduce future compaction is to incorporate compost topdressing as part of the aeration process. The organic matter in the compost will help build soil structure and reduce soil density.

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