By Adam Thoms, Iowa State University 

Topdressing is one of the most critical practices for quality turfgrass (Figure 1) but is also one of the most misunderstood and abused cultural practices that turfgrass managers conduct. Frequent sand-topdressing with pure sand was first described by John Madison in 1974, who noted that a uniform sand sized 0.05-1.0 mm should be used at a rate of 3 cu. ft. per 1,000 sq. ft. every three weeks in California up to 15 times per year. The original program was designed to limit the formation of layers of thatch and root zone material trapping thatch, ensuring that water flowed through the profile. Water will flow through a root zone freely if there is a coarse material over a fine material. However, once a finer material (one in which smaller particle sizes are present in greater numbers) ends up in the profile then the finer material must be fully saturated before water can move to the next layer below which slows the whole profile. 

The sand-topdressing program was amended in 1981 to account for different sizes from the original recommendation that were in the range of 0.1-1.0 mm , and noted that sand availability should be accounted for when starting a frequent topdressing program. Having to change sand sources frequently will lead to changes in particle size, which could result in layering in the root zone profile (Figure 2). Establishing a good flow of water through the profile (Figure 3) is critical for soils to avoid water backing up on the surface, which could result in ice formation and winter damage. Regular hollow tine aerification with the addition of sand-topdressing will allow water to continue to move into the profile. Often golf courses will debate the need to continue a sand-topdressing program especially if budgets are limiting, but the advice is generally that once a sand-topdressing program is started it should not be stopped.  

Sand topdressing is also often used before winter to help protect turfgrass plants from winter desiccation, which is the loss of water due to being exposed to dry winter winds in the absence of snow cover. Many golf courses will add a heavy sand-topdressing after the final mow and after irrigation blowout to the putting green surface to help protect the crown of the plant from winter desiccation. The sand-topdressing rates for winter putting green protection are often debated, so additional research is needed, but 3 cu. ft. per 1,000 sq. ft. is what is often used by superintendents. A WinterTurf research project led by Dr. Kevin of Michigan State University focusing on sand-topdressing for winter protection is being initiated this winter at several locations, so check back this summer to see the findings. 

References

Madison, J.H, W.B. Davis, and J.L. Paul. 1974. An alternative method of greens management. Proc. Conf. Cal. Golf Course Superintendents Inst. P. 81-88. 

Madison, J.H. 1981. Frequent sand topdressing vital tonic for greens. Golf Course. Manage. 17-20.