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nlunan@msn.com 203-537-0420 |
 "Broad Benefits of Biostimulants" |
We continue to hear of new technologies for sand-based athletic field management: sub-surface heating systems, sand stabilization systems, remote-control irrigation, GPS tracking, and the list goes on. However, 80-percent of all sports turf managers still maintain native-soil fields.
Native-soil field management poses many challenges. Some of the biggest problems begin with a lack of adequate internal drainage. Drainage: Drainage on native-soil fields is a major concern. The silt and clay particles that make up the largest fraction of native-soil composition are smaller than sand. The open pore spaces between these particles are smaller than those between sand particles as well. Smaller particles and pore sizes translate to lower infiltration and percolation rates, and native-soil fields need to be crowned or sloped to allow heavy rain to run off the surface. Standard slopes tend to be between 0.5 and 2.0 percent. University of Kentucky football field. Courtesy: Dan Bergstrom : Crowns on football fields can run the center of the field, or they can have a 'hipped roof' design. In the latter situation, the ends of the field fall toward the end zones. Baseball field crowns should start at the pitcher's mound, and should slope out in all directions. Outfield areas should fall away from the infield at a rate of 1.0 percent. Soccer fields usually have less of a crown; 0.5 percent is standard. A more pronounced slope threatens to interfere with play in the corners of the field, but sometimes it is necessary when heavier soils are involved. The debate over drain lines in native-soil fields continues. The technique places two- to three-inch diameter drain lines at 15- to 20-foot intervals either perpendicular to the field's crown or in a herringbone pattern. One of the biggest misconceptions about drain lines is that after they are installed, the native soil is used as backfill around the drains. Backfilling with the native soil will not help drainage problems, since water cannot percolate to the drain pipes any faster than it could on any other area of the field. Additionally, backfilled silts and clays can quickly accumulate in the drain pipes and render the system useless. Drain lines need to be covered with uniformly sized gravel. The trench should then be backfilled to the top with sand that is tested to percolate water at a rate of at least five inches per hour. It's also a good idea to line the sides and bottom of the trench with a geotextile fabric to keep the native soils from finding their way into the drain line. Another misconception about drain lines is that it is acceptable to sod over the top of the sand backfill. This defeats their purpose. The soil in the sod layer will not percolate at the same high rate as the sand below, and the line will effectively be capped. University of Kentucky baseball diamond. Courtesy: Dan Bergstrom : On bermudagrass fields, instead of capping the lines with sod, allow the bermuda to spread and grow over the sand-filled trench. Cool-season grasses should be seeded into the trench, or you can use washed sod to cover the lines. Even when sand-filled drain lines are properly constructed, they have a tendency to get des iccated during periods of extended dry weather. Fields that are irrigated regularly have few problems, but turf can struggle in sand drain lines on fields that are seldom irrigated. Aerification: Aerification is the most important cultural practice for maintaining a field's infiltration rate. Native-soil fields are subject to compaction much sooner than their sand-based counterparts because of the size of the particles and pore spaces that make up the soil. Pore spaces allow water and oxygen to infiltrate the soil to reach turf roots. Aerification loosens the soil enough to allow trapped carbon dioxide to escape the root zone, while opening pore space for oxygen and water to diffuse into the root system. There are several options when it comes to aerifying native-soil fields. Hollow coring times vary in diameter from 1/2 inch to one inch, and they vary in depth from one inch to 18 inches. Solid tines vary from 1/4 inch to 1 inch in diameter, and the range of depths offered is similar to that of hollow tines. Slicing tines open a narrow slit in the surface to depths ranging from 1/2 inch to 7 inches. |
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