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USGA Recommendations for Putting Green Construction the 2004 Revisions
This newsletter discusses some of the recent changes to the USGA Recommendations for a Method of Putting Green Construction. While there were many potential changes evaluated, there were only a few changes that were adopted. We believe that the changes that were adopted present a positive step towards continual improvement of the recommendations.
The USGA method provides excellent guidelines for greens construction, but these recommendations are not ideal for every situation. Factors such as cost, environment, and usage may make another design option more desirable. Whatever the specification or construction method, a good testing program should be an integral part of the construction process. Quality control testing helps to ensure that consistent materials are used throughout the project. Consistent materials are an essential part of a high quality turf system.
The United States Golf Association has recently revised their recommendations for putting green construction. The 2004 revisions are the latest update to the USGA recommendations, which have been in use for over 40 years. The last major revision was in 1993. This newsletter summarizes the changes as they relate to material selection and evaluation. A couple of factors affecting the selection of gravel (without an intermediate layer) have changed. The gravel/sand bridging criteria is now D15(gravel) < 8 x D85(rootzone). The uniformity factor for gravels has also changed to less than or equal to 3.0. In affect, these changes will allow for a wider variety of gravels to be acceptable for use in USGA greens. Larger and more widely graded gravels that formerly did not meet USGA recommendations, may now meet the revised recommendations. However, it should be noted that none of the other gravel requirements were changed. For example, no gravel particles greater than 1/2” is still part of the requirements. In addition, there are still guidelines for using an intermediate layer if an acceptable bridging gravel can not be found.
There was also a major change related to the performance characteristics of the mix. There is no longer an upper limit placed on saturated hydraulic conductivity (infiltration rate, percolation rate). The recommended range for saturated hydraulic conductivity is now a minimum of 6 inches per hour with no maximum rate.
The recommendations for sand size distribution, peat, and other organic amendments were not changed from the 1993 recommendations. However, the 2004 revisions now allow for the use of inorganic amendments in place of organics or in conjunction with other amendments. Inorganic amendments are allowed “provided that the particle size and performance criterion of the mix are met”.
Finally, there are recommendations concerning off-site blending (“absolutely essential”) and the importance of a quality control program during construction.
The information found in this newsletter was taken from the USGA Recommendations For A Method of Putting Green Construction by the USGA Green Section Staff. The complete text can be found on the internet at: http://www.usga.org.
USGA Greens Pocket Resource Guides
Our popular USGA Greens guides are available for free to those in the golf and turf industries. These guides are updated to reflect the 2004 recommendations. If you would like a copy, send an email request to turfdiag@turfdiag.com. |
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