Top-Dressing Sports Fields with RMP

Over the last few years the focus on athletic field maintenance has intensified. The primary reasons for this occurring, include an increase in sports activities, a shift from artificial grass to natural grass and a concern for liability and player safety.

Most field maintenance is the responsibility of athletic department administrators, turf managers and volunteer organizations who desperately need more information specific to each of their turf problems.

Topdressing is as essential to quality sports fields as any other cultural practice and must be included as part of the management plan. Applications should ideally revolve around periods of low play, although it may be utilized at any time.

The most significant problems related to sports fields are:

1. - Compacted soil, creating an unsafe playing surface.
2. - Destroyed grass and root system, by overuse.
3. - Muddy areas, created by improve drainage.

Why top-dress with RMP?

• Provide a resilient surface for safe play.
• Save $1330 per 1,000 SF per year in maintenance costs
• Improve agronomic and playing conditions. Top dressing is currently the only way to apply material which minimizes disruption to your field.
• Provide an uninterrupted slope for surface drainage to provide a smooth playing surface, which is critical for player performance.
• Provide adequate soil macro porosity for a better growing environment for grass by aiding the microbial community for thatch decomposition.
• Change soil texture. If the soil for your sports field is unsuitable and a complete change is not possible, a gradual change could be the answer. Over time soil texture changes and surface and soil conditions improve.
• Provide favorable environment for germination by enhancing seed to soil contact and reduce soil water evaporation.
• Create a cushion between the grass and soil, protecting the crown of the grass and RMP is not abrasive to the leaf tissue.
• Absorb some of the energy from downward pressure and torsion (twisting). This protects the turf's growing points, right at the surface.
• Provide winter protection for the grass plant.
• Increase heat retention, which provides earlier and later growing seasons.
• Increase the durability of turf used in high traffic areas.
• Increase the durability of turf used in high traffic areas.
• Increase the number of events from about 60 per year, for a normal grass field to about 100 for an RMP treated field.
• RMP does not damage sports equipment and mowers.

The area in front of the soccer goals and the midfield area normally wear down over the season, as does the area between the hash marks on a football field. Adding sand improves drainage and decreases muddiness, but it cuts the crown of the grass making the problem worse. Adding ¾ inch thickness of RMP in three applications of ¼ inch thickness, improves the turf survivability. The RMP size should be between 10/20-mesh and ¼ inch. EPPC recommends about one-half of the smaller size and one-half of the larger.

The RMP should be chosen with an understanding of the particle size and its relation with the existing root zone.

The key is to remember to top-dress with RMP crumb rubber that is at least equal to or coarser than the root zone material or the material at the surface. This will ensure that the macro pore space on top is greater and water will drain at the rate of the root zone profile.

Turf suffers when pore space decreases by even 10%. Soil compaction is a major of turf deterioration. Turf will grow slowly and will grow short, eventually it will become thin. Unhealthy turf means less play time and more repair time. Compaction stresses turf and turf takes more time to repair.

Soil compaction is the process of increasing the density of soil by packing the particles closer together and reducing the volume of air. It leaves no room for:

• Air exchange
• Water absorption
• Fertilizer absorption
• Drainage

Turf roots need water, oxygen, nitrates, phosphorous and potassium to grow. Soil compaction literally shuts out those nutrients, which preclude roots from growing deeply: they then grow laterally and shallowly.

Please note that increased amounts of fertilizer will not fully compensate for restricted root growth. If the fertilizer can’t get to the roots, putting on more will only waste time and money.

By top dressing with RMP each year, the rubber embeds itself further into the soil to make a compost layer under the surface. This opens the soil to accept fertilizer, air and water. This will leave an inert compound that will stay in the soil and protect the turf for several years.

Turf managers will benefit because it will be easier to manage grass that will require less fertilizer and water.

Field tests are showing the addition of approximately 15-20 % crumb rubber by total dry mass will enhance turf grass growth and playability of fine texture loam soils. The field test also suggested that 15-20 % rubber crumb significantly reduced soil surface hardness. Field test results also showed that soil containing more than 15 % crumb will experience decreased soil shear strength. In addition, rubber crumb decreased soil water content in the root zone, which researchers say may result in less damage to perennial ryegrass from “winter kill”. (Paul Grunthal, NRI Industries Technical Specialist)

Surface temperatures were significantly higher as crumb rubber levels increased. The effect of crumb rubber on surface temperatures was significant due to the relationship between turf grass growth and soil temperatures. As surface temperatures drop below 50 F the growth and recovery of turf grass slows. Keeping temperatures higher can lead to increased playing quality conditions. This also holds true in the spring time as well. The exposure of RMP at the surface heats the turf surface and revitalizes dormant turf grass. This translates to a quicker spring green-up, an important factor for any field used in the early spring. One concern we had was the effect of the crumb rubber on turf grass during the summer. As the density of the turf stand increases during the growing season, the effect of crumb rubber on surface temperatures moderates due to the shading of the turf grass, an effect measured and confirmed during 1993 and 1994. (Crumb Rubber project Michigan State University study)

By topdressing with RMP and choosing the appropriate species and variety of grass, you will prolong the wear tolerance of the turf grass stand and improve the playability of the field for a longer period of time. Pending on your turf grass selection and other management practices, re-establishment will be minimal in terms of dollar costs over the long run.

Seed may be applied at the same time as the RMP top dressing.

RMP - Installation

We recommend RMP Professional installation; with special mixes available, determined by soil conditions.

RMP may be top-dressed without aeration; this method requires 2 to 3 applications of approximately ½ inch of material per application.

Application of RMP for Top-Dressing Sports Fields

Application of RMP is applied by RMP turf and athletic experts, with professionally designed equipment. This equipment incorporates the rubber particles into the soil to provide immediate as well as long-term benefits.

New field construction is coordinated with engineers and field designers. RMP can be incorporated with existing soil to provide a base over the fields sub-base and also incorporated with the top soil layer with the seed.

Root System incorporated in soil with RMP	Side-line protection and elimination of mud

A proven athletic field improvement program is now underway on Indiana athletic fields. This improvement program is especially important with land for athletic fields at a premium. Extending the life of existing playing surfaces strategic for every school district and park district.

We top-dress turf-grass to improve both agronomic and playing conditions. The term is self explanatory, in that the material is applied to the turf-grass surface from above. This is currently the only way to apply material while minimizing disruption to your field.

RMP will not resurrect your turf-grass stand after wear damage has already destroyed the root system. Therefore, for an existing athletic field the best time to add RMP is before the start of the new season when your turf cover is the greatest. Use RMP that has a 10/20 mesh particle size and top-dress it in at ¼ inch (1/4 inch = 600 lbs. of RMP per 1000 ft.) intervals until you have added ½ to ¾ inch of the material.

Not more than a ¼ inch thickness of RMP should be spread during any one given application according to the MSU study. Therefore, you need two applications for ½ inch and three for ¾ inch. We recommend ¾ inch.

The time between each material application should be long enough for the rubber particles to work down to the base of the grass. This is usually until after the next rain, athletic event or mowing. During the winter the freeze and thaw moves the particles to the root area.

The effect of incorporating RMP with existing soil, in areas devoid of vegetation and having compacted soil, will be dramatic and enable the turf to be reestablished more quickly and prevent re-occurrence of problem areas.

The time of the year is not terribly critical but it is generally recommended that the material be applied prior to the start of the growing season. The best aid in having the particles migrate into this interface is actively growing grass. Therefore the material should be in place before and during the growing season.

The material does not have to be aerated or otherwise mechanically incorporated into the soil. Studies have shown a top-dressing application will show results in the first season. However, if speed of incorporation or soil conditions requires aeration, RMP is able to provide professional aeration.

Don’t be afraid to apply seed at the same time as the RMP application.