Tips From The Pros

SPORTS FIELD SOD – PART 2: IN THE FIELD

Last month, I discussed some tips on specifying your sports field sods. This month, we take it out to the field and look at some keys to successful sports field sod installation and preparations for play.

Remember, every sand-based field sod project has unique requirements and these recommended practices are not intended to replace the need for project-specific consultation. Rather, these tips are intended for the facility owners/operators, field managers and field designers to use in planning a successful sod operation for new field construction and as part of today’s routine maintenance programs for high-performance sports fields.

Tearing out the worn surface.

First, when doing field sod repairs, make sure to re-sod out well into the heathy grass. Even with today’s technology a field repair can be tough on the existing grass, especially near the edges with the new sod installation. I see too many field repair patches that try to save money and work and the patch is too small for the worn area. By the time the work is done, you have a “sod oasis”.

In the old days, we had few good options on how to efficiently remove the worn out surface grass. Generally, a walk-behind sod cutter (or sometimes a large harvester) are run through the ground at a depth near what the incoming sod thickness will be. We then dug out the worn grass by hand and with tractor loader. The chunky grade left behind was slowly and meticulously graded by hand using mason strings across the cut to get the grade correct.

Today, we have pull-behind milling machinery to make quick easy work of it while also leaving a near sod-ready grade behind.

You can see a video of a milling machine removal of worn grass here and the obvious efficiencies.

Setting a good sod bed.

The bed you will be laying the sod on is critical to a successful installation. Good sod on a lousy bed doesn’t work.

The bed should be smooth and in line with the original surface grade design of the field. A wavy bed often won’t show until you paint the first wavy lines on the field of play, when it’s too late to correct the grade. Your depth of cut should match the sod harvest thickness.

It’s important to note that the same soil physical and fertility characteristics that make for healthy turfgrass growth and development will apply to your sod bed. Keep in mind that areas of the field worn to the level of requiring sod repair will typically have some level of soil compaction. This needs to be remedied before you start pulling a final grade. So first up after removing the worn grass is doing any compaction relief that may be needed in the soil. Depending on the level and depth of the compaction in your sod bed, there are many machines designed to relieve compaction in the soil from simple roto-tillers to more field-specialized pieces of equipment like bleco-vators and others. Now may be a good time to mix any organic or inorganic soil amendments into the soil of the sod bed. Some fertilizers may also be mixed in or simply applied to the sod bed surface in advance of sod install. Water to settle as needed.

The ideal sod bed will be firm enough to handle the equipment and work of the installation and play on the field. Similar (in ways) to the ideal baseball/softball skinned area infields, the idea is firm underneath with a thinner layer of loose material on top. Get your moisture and tilth right and you’ll walk on firm ground but leave footprints.

Harvest. How thick, wide and long to cut sod rolls.

A very important consideration is the thickness at which the sod will be cut during harvest, as is the width and length of the rolls. Today’ projects often call for an expedited opening of the field, and in-season field repairs by necessity must be ready for play quickly. Harvesting the sod much thicker than lawn sod, which is typically cut at about ½ inch thick, adds weight and earth mass and may better handle the traffic requirements and physical stresses on the fields of play. Even as the surface naturally wears out with play, the thick-cut sod may be less likely to suffer significant failures which may occur when sodded fields wrinkle, buckle and flap during play. There are few if any industry accepted standards I know of, and little research to use as a guide. The recommended approach is to err on the side of too thick, rather than too thin. It can take a full season or more for the sod to adequately root into the rootzone sand at the stadium and become stable enough for play and the mechanical forces imparted by events and maintenance. Sod cut too thin may not be heavy enough to avoid wrinkling or coming up in flaps during cleated play, leading to failure of the field, poor play and may increase the risk of player injury.

Traditionally cut sods for sports fields will generally be between ½ and 2-inches thick, depending on how much time there is for tightening the surface and establishing the grass on the field. There are limits to the thickness on traditionally cut sods. Too thick a cut may not hold the soil and roots together through harvest, transport and install, possibly creating a bumpy finished surface. The added weight from thick cuts will add significant costs to the sod in terms of trucking. You are also buying more of the sod farmer’s soil.

Beyond just deciding on your sports field sod thickness, you will want to determine the ideal length and width to cut the rolls. The idea is to cut the rolls as long as practically possible to minimize sod seams on your finished install. Generally, rolls are cut between 25 and 60 feet in length, depending mostly on the sod thickness and strength of the sod. Thicker cut sods, weighing more, cannot be cut into rolls as long as can be cut with thinner cut sods. Another consideration with length of sod roll cuts is that the heavier the roll of sod harvested, the more vertical stretch will occur at installation. So a typical 30-foot long roll of thick-cut sod will generally roll out to a length of 35 feet or more in my experiences. This loosening of the surface being installed may create loose footing. Vertical stretch can run anywhere from 10-30% in my experiences. And there is not much you can do about vertical stretch at install except use healthy, mature sod and shorter roll lengths.

Sod roll length also must fit into a practical sod trucking (transport) system. Due to the size and weight restrictions on the trucks and limited number of rolls you can stack on top of each other for transport, you will have to find the sweet-spot for sod roll length for each project.

Sod width is another consideration. In traditionally cut sod, the sod roll width will be limited by the effective length of the sod cutter’s bed knife. 4-feet of width is about the limit for a sod cutter bed knife that must cut through soil and roots. Any wider and the bed knife may begin to warp and bow during cuts, potentially creating inconsistent thickness of cuts. The added stress of wide cuts may even break a sod cutter’s bed knife. Sometimes, you will see rolls of sod in a 2 x 24-inch arrangement as it comes off the harvester. This may create more consistent thickness, which is key, but also creates more seams to mitigate on the field after installation. Seams are the part of the sod-installed playing surface where the rolls of sod meet each other. Longer and wider rolls of sod will minimize the amount of seams in the installed field. However, there are limits to the harvesting, handling and installation equipment used in terms of weight and size.

Transport

Too many projects leave the logistics of transporting the sod rolls from the farm to the stadium playing field to the sod farmer alone. Many variables and limits need to be managed to get the best results. Sod transport trucks have highway weight limits. They can only be so wide and long. Sod rolls are best transported unstacked, but this can get expensive and if you have strong, nature sod, I allow for one roll stacked on top of two rolls, maximum. A practical goal is to harvest, transport and install each roll of sod in 24 hours or less. Climate controlled trucks may be needed at certain times of year.

Have a staff member out at the farm for harvest whenever reasonable. They can be checking sod thickness and quality before it is loaded and transported. Good coordination between the sod farm and installation site is critical.

Turf Tips 101: Sports Field Sod Installation.

A well prepared sod can be ruined with poor installation techniques, especially thick cut sand-based sods. As sod rolls are rolled out in various fashion, the sod will be unavoidably stretched to a certain extent by its own weight. A 30-foot long roll of thick cut sod can measure 35 feet or more after it has been unrolled at the stadium. This loosening, when excessive, can affect the surface stability of the new playing surface and should be minimized with careful installation. Care should be taken to unroll the sod as closely as possible to the previously lain sod, leaving no more than a 1-inch gap. Sod should be pushed into place with lateral compression, not pulled. Leaving large gaps so that the sod must be pulled over by a team with large forks will only serve to loosen the sod more and may create an uneven surface as the rootzone sand piles up in the gaps as the sod is pulled over. Any poking, prodding, lifting and other mechanical stresses imparted to the sod after it has been unrolled should be held to a minimum; all of this tends to loosen the playing surface.

Lateral compression.

Recent years have seen a growth in the popularity of laterally compressing the thick-cut sod rolls after installation with specialized equipment like the SideKick. In my opinion, this type of lateral compression of the sod, post-install, significantly tightens up the playing surface and tucks sod roll seams together nicely. It is lateral compression of the sod, so I don’t know if that completely solves the vertical stretch on install, but lateral compression is key in my opinion.

Lateral compression reduces sod roll width about 3-5% in my experiences. So a 48-inch wide roll, after rolling-out and vertically stretching, may laterally compress down to a 45-inch laterally compressed width. As such, you have to account for this in your project quantity take-offs. When laterally compressing sod, it may be wise to account for this 3-5% and order more total sod for the project accordingly.

Sod and rootzone protection.

Almost all big-roll sod installation machines and techniques involve one set of tires or tank-like tracks that must roll over the top of previously installed sod. It is important that the equipment used for the installation of the sod rolls have wider and smoother ‘turf’ tires. Depending on the situation, long strips of plywood can be laid on the previously lain sod for load-bearing protection. This can add costs and labor to the install but may be essential. The thick-cut big rolls are quite heavy and rutting the previously lain sod must be avoided to ensure a quality installation.

The rootzone that the sod is installed on may be easily rutted as well by installation equipment tires and tracks. Usually, this surface disruption is fairly shallow and can be easily repaired with a simple drag matt (or equal). A cart, matt and operator should be dedicated to this procedure to keep the work flowing smoothly. All surface disturbances and depressions left on the rootzone (sod bed) during the installation process should be immediate repaired before the next row of sod installation begins.

Irrigation.

Recently cut-harvested sod has been root-pruned. As such, the plant may be prone to drought stress as there are less roots to mine water as needed. It is smart to immediately irrigate your traditionally cut sod roll quickly after installation. A light irrigation using the irrigation system or hoses typically follows quickly behind the installation once the work has progressed far enough along that the water won’t interfere with the work. This will help wash down any soil dropped on top of the sod during the unrolling process and give the grass some needed water after the root-pruning of harvest. A deeper irrigation cycle, which will bring the whole profile to field capacity, should be conducted as soon as it is safe to do so.

Rolling

Depending on the condition of the newly lain sod surface, a light-moderate rolling is typically indicated on the sod after any post-installation irrigation has drained well. Do not roll a saturated sod. This will help firm and smooth-out the playing surface. Some of the heavier ride-on rollers are typically rented or borrowed, as this is not a frequently used field management technique in most cases. If using an outside roller, first thoroughly inspect the unit for any hydraulic, oil or gas leaks. Clean the rollers. On the field, test the rolling operation in a safe and less-important part of the playing surface like sideline areas to gauge the results and techniques before proceeding to the main part of the field. Roll newly lain sod first in the same direction as the rolls were installed. You will hit fewer seams and minor depressions head-on this way and the sod is less likely to slide or wrinkle during rolling. As the sod settles with time and sod rolls key together, diagonal and cross rolling may be indicated

Seam Inspection and Mitigation

After rolling (when indicated) seam inspection/mitigation work can begin. Walk and inspect every seam on the field to check for any gaps more than 1/8-inch and pay close attention to the corners of the installed sod rolls. Fill in any minor gaps and depressions with an appropriate rootzone mix and broom in to smooth the surface. Topdressing the newly lain sod is next. Use sand identical to your rootzone mix, minus any amendments for topdressing the playing surface. A light topdressing (5-6 tons sand/acre) is almost always a good idea, and a higher rate topdressing (6-10 tons/acre) may be indicated to aid with traction and smoothing the surface. Gently broom-in the topdressed sand.

Fertility on Newly Lain Sod

Your fertility program on the newly lain sod should be an extension of the program at the farm. No special fertility applications should be necessary on the newly lain sod if it was properly managed at the farm. Simply keep the schedule going and address deficiency symptoms as you normally would.

Mowing

Mowing the newly lain sod can start as soon as it is safe to do so and once the grass is long enough to need mowing. Mowing will begin to eliminate sod-roll grains and help stand up all the grass more vertically. Setting in game-mowing patterns as soon as possible is always a good idea and can be done with a gentle pull-behind broom to enhance what the mower does. Mowing may also help smooth-out minor imperfections in the newly installed playing surface.

Game Prep

Allow adequate time in the schedule to re-measure and survey the layout(s) of your new playing surface if necessary and do any painting/marking and final field prep before any play begins on the newly installed playing surface. Getting any field in championship condition takes time. And while the players will appreciate the attention paid to the playability of the new surface, the media and fans will appreciate an attractive appearance.

Next month in Tips from the Pros: Part 3: Plastic-Grown Sod – The Future is Here.

Resources of the Month

Settlers and homesteaders in the great American prairies didn’t have trees to build with. Sometimes, they had to build a structure to live in within months of arriving to keep their land grant. Sod houses or “Soddies” were the way to go. See the story of one great Soddie here.

A 1903 US Patent for a horse-pulled sod cutter.

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“Water plus sod equals grow” - My landscape construction foreman in 1976.