Particle size is determined using standard operating procedures from the American Society for Testing and Materials (ASTM). Particle size testing of bunker sands provides information related to properties of the bunker, as well as, the sand’s affects on nearby greens.
The particle size analysis is the primary means for evaluating the potential impact of the bunker sand on the agronomics of the green. In many cases, the particle size distribution should approximate United States Golf Association (USGA) specifications for putting green construction in order to not create a layering of the surface from the effects of explosions of bunker sand onto the putting green areas. Coarse or gravelly sands may place unwanted particles on the green and result in a surface with obstructive particles that could impair putting and mowing operations. Fine sand particle accumulations on the green's surface may cause irregularities of water movement and the overall physical characteristics of the rootzone.
The USGA publication Turf Management for Golf Courses (2002) by Dr. James B. Beard has recommended a narrowly graded sand for bunkers. From a pure agronomic view the range is desirable, but the availability of sands that have desirable ball lie characteristics with the narrow range of particle size suggested by USGA may be limited. It is often the case that a more desirable ball lie is achieved with sands that have a wider particle size distribution.
To minimize the effect of fine sand content on the green surface from either bunker shots or wind erosion, an alternative is to use a sand that is of the same particle size as the rootzone mix or greens sand. A comparison of Dr. Beard’s bunker sand size recommendations, the 1993 USGA particle size recommendations for greens mix, and the particle size of sands acceptable for “California Greens” is listed in the table below.
Comparison of Particle Size Recommendations for Bunker and Greens Sand
Turf Diagnostics & Design
Helping You Have Healthy Turf
Issues 1 and 2* 2002
Bunker Sand Evaluation
This newsletter continues our series delving in to the sometimes mysterious physical test reports you get from our lab and others. This newsletter discusses bunker sand testing and selection. The bunker sand assessment is designed to evaluate the proposed or existing sand from a performance perspective, as well as the impact on the agronomics of the putting green. The performance aspect of the sand for bunker use involves the ball impact characteristics as well as maintenance factors. "Ball-lie" is a term that describes how the ball sits in the sand after impact. To the golfer, the ball-lie is probably the most important aspect of the performance of the sand.
The bunker sand evaluation process involves three distinct parts. The particle size analysis, infiltration rate testing, and the bunker evaluation test series. The penetrometer test, color, shape, crusting, and set-up make up the bunker evaluation phase. The particle size and infiltration rate analyses are determined using standard operating procedures from the Methods of Soil Analysis (American Society of Agronomy) and the American Society for Testing and Materials (ASTM). The sand size distribution is based on the United States Department of Agriculture (USDA) definition of sand grain classification. The bunker evaluation test series is conducted using the procedures published in Golf Course Management (1986, 54:64-70).
Particle shape is related to the ball-lie characteristics. Typically, sharp angular sand will provide a more desirable ball-lie than a rounded sand. The crusting and set-up tests are related to the sands tendency to form a hard layer on top after rain or irrigation. Ideally, the sand will not crust or set-up.
Beard, J. B. 2002. Turf Management for Golf Courses, 2nd Ed. p. 259-281. Ann Arbor Press, Chelsea, MI.
Brown, K. W. and Thomas, J.C. 1986. Bunker Sand Selection. Golf Course Management. 54:64-70.
Std Test Method for Particle Size Anal. and Sand Shape Grading of Golf Course Putting Green and Sports Field Rootzone Mixes. Nov 2001. F1632-99. ASTM Vol. 15.07.
Hydraulic Conductivity of Saturated Soils. 1986. A. Klute (ed.) Methods of Soil Analysis Vol. 1, Agronomy 9:687-703. Amer. Soc. of Agronomy, Madison, WI.
Moore, J. USGA Green Section Record, Jan/Feb 1998 Vol. 36, #1.
USGA Green Section Record March/April 1993.
The Sand Putting Green Construction and Mangement, Cooperative Extension Univ. of California Div. of Agriculture and Nat. Resources, Publication 21448.
We recommend performing the particle size test in conjunction with the bunker test series and infiltration rate testing when evaluating bunker sands. This bunker sand evaluation process should provide a good indication of how the sand will perform in the bunker and affect nearby greens.
While these tests are great indicators when choosing a sand, construction and maintenance practices will have a profound affect on the actual performance. The slope of the bunker and surrounds, and the presence (or lack) of a subsurface drainage system will also have a big affect on the performance of the bunker.
Color is important from the aesthetic viewpoint but does not affect performance. Sand color is reported on wet and dry samples with the Munsell Color Chart Book. Color is typically reported with a number containing the hue, value, and chroma, with the color name following. Lighter colored sands are often preferred because they provide a nice contrast with the turf. Color is more of a personal selection, and the sand color is often dependent on local availability more than performance criteria.
Infiltration rate (saturated hydraulic conductivity) data provides an indication of how well the sand will drain after rain or irrigation. An infiltration rate of greater than 20 in/hr suggests that the sand should drain well.
The performance of a particular bunker sand is largely the result of the sand size distribution and particle shape. Bunker properties, such as, drainage rate, crusting, and set-up are negatively affected by very fine sand, silt, and clay. A minimal amount of these particles should be part of the selection criteria. Sand shape has an affect on ball lie, with angular sands providing better lie than round sands.
The penetrometer test is used to evaluate ball-lie in the sand. Moderate to very low tendencies to bury the ball are the more acceptable ball-lie ratings. A high tendency to bury the ball is not desirable in a bunker sand. The following penetrometer values are used to rate the ball-lie characteristics.