SPORTStURF ROOTZONE (SRM) SANDS
By Powell Gaines, Tifton Physical Soil Testing Laboratory, Inc. (Unpublished)
A Sportsturf Rootzone Mix (SRM) Sand for athletic field construction should have more fines (total of very fine sand, silt, and clay) than a USGA golf green construction sand because it has to withstand the heavy mechanical stress associated with the rigors of athletic competition. For example, a football scrimmage on a USGA golf green would be quickly destroyed because the players’ cleats would rip through the canopy of the green. Fines are needed in an SRM to allow the field to set up firm, not loose, to ensure good footing.
Coarse sands should not be used for SRM Sands because they would cause the field to set up loose with unstable footing and would be a slow track. Also, the field would require more unnecessary maintenance to overcome drought and fertilizer leaching. If coarse sand is used, it should be amended with 10-20% soil to develop an SRM with optimum physical properties. Optimum physical properties for an SRM for athletic field construction would be a water permeability rate of about 8-15 in/hr., a good balance in the non-capillary (air-filled) and capillary (water-filled) porosities, and water retention of 12-18% to reduce fertilizer leaching. Rototilling 80-90% sand into an old existing loamy soil sports field to develop an SRM with optimum physical properties is not an exact or practical way to develop an SRM with optimum
physical properties. For an 8" cap, this would be removing about 6-7" of the existing field, rototilling 6.4 - 7.2" of sand into only 0.8 - 1.6" of soil, which would not be an exact or realistic way to establish a good uniform 8"cap. Instead, using 8" of a straight “dirty” fine sand with about 6-10" silt and clay would serve the same purpose and would involve a lot less work, be less expensive, and would be a better, more uniform sand cap.
To eliminate the need of mixing a large amount of sand with a small amount of soil to develop an SRM with optimum physical properties for an athletic field, fine “dirty” sand could be used instead. Such sand could be used straight with no soil amendment because such sand already has an adequate amount of fines to allow the field to set up firm, not loose, to ensure good footing. Also, dirty fine sand with about 6-10% silt and clay (<5% clay) would have a water permeability rate of about 8-15 in/hr., a good balance in air-filled and water-filled porosities, and adequate water retention of 12-18%. Dirty fine sands can be local unwashed creek bank sands which typically fit this description. Such sands usually are considered low-quality sands because of the 6-10% silt and clay (mostly silt) and would be expected to be relatively less expensive than higher-quality washed sands. Dirty fine sands can be the “finished product” and are good Sportsturf Rootzone Mix (SRM) Sands that our lab recommends for athletic field construction.
A Sportsturf Rootzone Mix (SRM) Sand for athletic field construction should have more fines (total of very fine sand, silt, and clay) than a USGA golf green construction sand because it has to withstand the heavy mechanical stress associated with the rigors of athletic competition. For example, a football scrimmage on a USGA golf green would be quickly destroyed because the players’ cleats would rip through the canopy of the green. Fines are needed in an SRM to allow the field to set up firm, not loose, to ensure good footing.
Coarse sands should not be used for SRM Sands because they would cause the field to set up loose with unstable footing and would be a slow track. Also, the field would require more unnecessary maintenance to overcome drought and fertilizer leaching. If coarse sand is used, it should be amended with 10-20% soil to develop an SRM with optimum physical properties. Optimum physical properties for an SRM for athletic field construction would be a water permeability rate of about 8-15 in/hr., a good balance in the non-capillary (air-filled) and capillary (water-filled) porosities, and water retention of 12-18% to reduce fertilizer leaching. Rototilling 80-90% sand into an old existing loamy soil sports field to develop an SRM with optimum physical properties is not an exact or practical way to develop an SRM with optimum
physical properties. For an 8" cap, this would be removing about 6-7" of the existing field, rototilling 6.4 - 7.2" of sand into only 0.8 - 1.6" of soil, which would not be an exact or realistic way to establish a good uniform 8"cap. Instead, using 8" of a straight “dirty” fine sand with about 6-10" silt and clay would serve the same purpose and would involve a lot less work, be less expensive, and would be a better, more uniform sand cap.
To eliminate the need of mixing a large amount of sand with a small amount of soil to develop an SRM with optimum physical properties for an athletic field, fine “dirty” sand could be used instead. Such sand could be used straight with no soil amendment because such sand already has an adequate amount of fines to allow the field to set up firm, not loose, to ensure good footing. Also, dirty fine sand with about 6-10% silt and clay (<5% clay) would have a water permeability rate of about 8-15 in/hr., a good balance in air-filled and water-filled porosities, and adequate water retention of 12-18%. Dirty fine sands can be local unwashed creek bank sands which typically fit this description. Such sands usually are considered low-quality sands because of the 6-10% silt and clay (mostly silt) and would be expected to be relatively less expensive than higher-quality washed sands. Dirty fine sands can be the “finished product” and are good Sportsturf Rootzone Mix (SRM) Sands that our lab recommends for athletic field construction.