As another season begins, spring tasks such as checking bunker sand depths are happening throughout the Northeast. Over time, bunker sand is moved or displaced due to play, washouts, maintenance and other factors. Several times recently in my travels I have heard the complaint: “There’s no sand in the bunkers!” While a lack of sand is sometimes the case when bunkers play too firm, adding more sand is not always the answer.
Bunker sand infiltration rates can reduce dramatically within just a few years of installing new sand. This occurs naturally as sand traps leaves, grass clippings and soil particles. As more organic matter and soil particles accumulate in bunker sand, more water is held and the sand will play firmer even if there is plenty of it. Things can seem even worse during the winter and early spring because bunkers are raked infrequently and weather tends to keep sand wet. Warmer weather and more raking may solve the problem, but if the bunkers continue playing firm you may need to replace contaminated sand.
So, when it’s time to replace or add bunker sand, how is the proper depth determined? Typically, 4-6 inches of sand on bunker floors performs well, but liner systems have become more common and some create a perched water table. I find 4-6 inches is often not enough sand to adequately move water away from the sand surface with certain liner options. This is where having an accredited laboratory perform a moisture column test can help. During this test, the bunker sand is saturated and moisture content is measured every two hours over a 48-hour period. Moisture measurements are made at 0 (bottom of the column) and 4, 6, 7 and 8 inches from the bottom. For a good minimum sand depth in your bunkers, add 1 inch to the depth at which moisture levels dry to 15% after 48 hours. So if the sand has 15% moisture content at 6 inches after 48 hours of drying, you want 7 inches of sand in the floor of your bunkers.
If you want to discuss bunker sand selection and installation practices further, please reach out to your regional USGA agronomist.
Northeast Region Agronomists:
Darin Bevard, senior director, Championship Agronomy – dbevard@usga.org
Elliott L. Dowling, regional director, East Region – edowling@usga.org
Brian Gietka, agronomist – bgietka@usga.org