1998 Iowa Turfgrass Research Report

1998 Iowa Turfgrass Research Report

Stabilizing Sand-based Athletic Fields With Enkamat

David D. Minner and Jeffrey J. Salmond

Objectives

The objectives of the study are to determine the proper placement depth for Enkamat and to evaluate it as a stabilization material for sand-based systems.

Sand-based systems are widely used for sports fields to reduce compaction and promote rapid drainage. Sand is an excellent media for drainage of the rootzone, but it can result in an unstable surface, especially when the grass has worn away. New technologies are being developed to stabilize sand-based fields. Fibrillated polypropylene fibers woven into a synthetic black backing (SportGrass™), fibrillated fibers (TurfGrids®), and interlocking mesh elements (Netlon, Ltd.) are a few of the products available for stabilizing sand-based athletic fields. Reinforcement material can be grouped into two categories: those that form a horizontal layer at or near the turf surface and those that are comprised of individual discrete units that are mixed into the rootzone layer (Baker, 1997).

Enkamat consists of a bulky mat made from nylon threads that are fused together where they cross. The thickness of this three-dimensional mat ranges from 11/16- to 7/8-inch and has an open construction leaving 90% of its volume to be filled with sand or soil (Baker, 1997). Enkamat has been used in combination with other geotextile material (polyester covers, TurfArmor®, and plywood) to protect the grass surface when special events are held on stadium fields.

Demonstration plots have shown that if the Enkamat is exposed to the surface, during field wear, there is a potential for tripping with cleated shoes. We are interested in how deep Enkamat needs to be placed to prevent exposure to the surface and if there is any benefit from field stabilization with Enkamat.

Methods

A 50 ft by 50 ft sand-based pad, six inches deep, was constructed in the fall of 1997 for evaluation of Enkamat at the Horticulture Research Station, Ames, Iowa. The sand-based system was placed over a 4-inch gravel blanket with a network of 4-inch drain pipes. The sand rootzone is described below and no other physical amendments were added. The study area is automatically watered and is part of our new sand-based sports turf research facility. Table 1 shows the treatments that were installed to evaluate Enkamat as a reinforcement material for sand-based athletic fields.

Table 1. Treatments used to compare the reinforcement capability of Enkamat on sand-based athletic fields.

Trt	Synthetic	Depth of synthetic below sod (sod contains 0.75 inches of soil)	Comments
1	Sand	--	Standard for the industry
2	Enkamat	0 (0.75 inches)
3	Enkamat	1 (1.75 inches)

The experimental design is a randomized complete block with three treatments and three replications. Individual treatment plots are 13 ft. by 16 ft. The large size of the plots will allow for study of an additional factor by sub-dividing each treatment plot. Potential split plot treatments could include typical field management factors such as topdressing or drill seeding. Enkamat will be placed at two different depths to ensure that it will not become exposed during intense traffic. We will determine if Enkamat provides any advantage for turf growth, even when placed deep enough in the soil profile to avoid surface exposure. Enkamat will be placed at two depths, even with the surface of the sand base or one inch below the surface of the sand base. In treatment #2 the top of the Enkamat is even with the top of the sand surface. When sodded, the top of the Enkamat is then covered by 0.75 inches of soil. In treatment #3 the top of the Enkamat is placed one inch below the surface of the sand. When sodded, the top of the Enkamat is then covered by 1.75 inches of soil. The study area was sodded on 7 November 1997 with 'Midnight' Kentucky bluegrass containing 0.75 inches of a Nicollet fine loam soil. Sod laid on sand-based fields is the current standard for the industry. In northern climates sand-based fields are seldom established from seed. Enkamat reinforced fields will need to show an improvement over the conventionally accepted sand fields that are sodded. Turf will be mowed, watered, and fertilized to simulate a high maintenance sand-based sports field. Turf will be mowed, without catching clippings, at a 1.5-inch height three times per week. Water will be applied through an automatic watering system at the first sign of wilt. Approximately 1.5 inches of water will be applied each week from May through September. Nitrogen will be applied at 1 lb N/1000 sq. ft./growing month. Phosphorous, potassium, calcium, magnesium, and micronutrients will be applied based on soil testing.

From May through August plots will be evaluated for turf appearance, surface hardness, and traction. From mid-August through September all treatments will receive simulated traffic treatments. Traffic will be applied every Monday, Wednesday, and Friday with a model T224 Brouwer roller that has been converted into a riding traffic simulator. Both of the two-foot wide rollers on the traffic simulator are fitted with 5/8-inch football cleats on 2-inch centers. The rollers are attached by chain and sprocket to supply a differential-slip-type traffic that produces a tearing action of the grass surface. Turf will be evaluated during a non-traffic recovery period from 1 October to mid-November. The entire study area will receive both hollow and solid coring in 1998 to determine if Enkamat disrupts this routine management practice.

Baker, S.W. 1997. The reinforcement of turfgrass areas using plastics and other synthetic materials: a review. International Turfgrass Society Research Journal, 8:3-13.

¬ N

Sodded November 7, 1997

'Midnight' Kentucky bluegrass

¬ 13 ft. ®

1	2	3	&endash;   16 ft.   ¯
3	1	2
2	3	1

Objective: To determine required depth of placement for Enkamat.

Treatments:

Installation procedure:

ISU Horticulture:Publications:1998 Turfgrass Report

College of Agriculture