Every golf course usually has a preference weather they would like you to fill your divot or replace it. This varies from course to course because of different grasses or even different climates. Here at Piedmont we ask you to replace your divots if it is still in one piece and when temperatures are cooler(spring, fall, winter). If the divot is shattered into a bunch of small pieces and or during the warmer months of June, July and August we ask you to fill it with sand. During the warmer months the divot will usually die due to heat and lack of water. Where as during the cooler months the divot can recover and root back into the ground which would have quicker recovery then filling it with sand. If you walk and don't have sand with you we ask you always replace your divot. Attached are a couple videos from the USGA about fixing divots and ball marks. Thank you for all your efforts in helping maintain your golf course.
Fixing Divots
Fixing Ball Marks