Drainage management

Soils for sports turf must have good footing and traction for athlete safety and performance.

Soils that are easily compacted, have a low amount of organic matter, have poor nutrient and water holding capacity and poor drainage are not suitable for sports turf.

Organic soil amendments (i.e. compost, peats) function by enhancing soil structure (in non-sandy soils) and aeration as well as contributing to improved nutrient and water retention. Soil resiliency can also be increased with organic amendments. Learn more about composts and compost testing.

Inorganic amendments (i.e. sand, calcined clay, diatomaceous earth) can be used to improve drainage and aeration along with water and nutrient holding capacity.

Long term improvement in soil properties can be achieved by topdressing. Topdressing with ¼ – ½” of screened high quality compost or lesser amounts of sand after aggressively core aerating the soil will begin to improve the soil’s drainage and aeration properties. Depending on your goals this may need to be repeated a couple of times per year.

Compaction

Compaction breaks down soil structure and reduces the amount of pores space for air exchange, which is necessary for root growth and microbial activity. It also reduces the amount and rate that water can infiltrate into the soil and percolate down through the soil profile.

Compaction is more likely to occur on fine-textured soils and less likely a problem on fields with coarse textured soils.

Management options include various cultivation practices such as coring, slicing, spiking, grooving, water and air injection, drilling and solid tine cultivation. These operations still must be done at the correct time, at the proper depth when soil conditions are not wet and are required more often on high use fields.

Drainage

Drainage is the removal of excess water from the soil surface and/or soil profile either by gravity or artificial means. Some fields may have adequate drainage because the field was constructed properly. However, poor drainage is one of the most common problems of high use sports fields.

Improving Surface Drainage

When water remains on the field surface and does not drain many problems occur including slippery and unsafe conditions. Games are cancelled and maintenance practices are delayed.

Wet soils take a longer time to warm up in the spring and seed germination can be delayed.

The raised portion of a sports field that provides a slope to promote runoff of surface water is called the field “crown”. Crowns are the most effective way to remove surface water because they move water the shortest distance possible.

Football fields should have at least a 1-2% slope. The highest point is usually about 10-18” above the lowest point on the field. Soccer fields made of native soil typically are built with a minimum of 1½ % slope and should never be flat. If the fields have underground drainage the slope should be at least 1%.

Crowned fields are not suitable for multiple sports because they cause difficulty in ball control sports like soccer and field hockey.

The water that is directed to the sidelines will need to be collected by interceptor drains and move away from the field.

Improving Sub-surface Drainage

Sub-surface drainage can be effective at removing excess water from the rootzone during high rainfall events and for reducing the water table. These systems assist in moving water out of the soil profile by providing a pathway for “excessive” or “drainable” water to leave the soil. They work the best when good surface and internal drainage are in place.

There are a few commonly used systems to help improve sub-surface drainage including pipe drains, interceptor drains (also known as French drains), trackside drains, strip drains and sand-slit drains. A thorough discussion of each of these methods can be found in fact sheets from the Sports Field Management Association.

Use the information to assess your drainage problem and select the appropriate approach for correction.

Building a Sand-Cap

Michigan State University (MSU) offers an alternative to complete renovation of native soil fields with high silt and clay content and drainage problems. The Sand-Capped System uses the installation of a subsurface drain tile system followed up by sand topdressing to build up the soil profile over time.  See Sand Cap Build-Up Systems for Michigan High School Fields.

There are four steps for building a sand-capped system. Based on 2008 cost figures the system can be built for $58,200 – $103, 800 (this includes an irrigation system installation ($15,000), 6-20 foot drain tile spacing ($14,200 and $60,000, respectively), and a 2-inch sand layer depth ($28,800). It is believed that this would provide a cost effective solution to improve field playability that does not interrupt field use for an extended period of time.

Steps include:

• Cutting drain lines in the existing field running length wise
• Putting drain tile in the lines
• Back filling with pea stone and then sand or coarse sand alone

MSU suggests installing an irrigation system (before the drain tile installation) if one is not present because turf grown on a sand-based system will need regular irrigation. Be sure to correct any low or wet spots in the existing site and repair any drainage line damage found.

Once installed, an aggressive sand-based topdressing program must be initiated and maintained using a well-graded sand-based material ~90% sand: 10% silt/clay.