Maples are thin-barked trees, making them susceptible to frost crack. Was this tree wrapped the first several years during the winter? This may be the reason for the crack you noted may have been there several years. It is highly recommended that young (the first 4 years), thin-barked trees be wrapped November to April which helps insulate the bark from temperature fluctuations. Warm temperatures during the winter will bring the tree trunk out of dormancy, only to have temperatures drop resulting in the freezing of cells and tissue causing severe cracks.  

As far as recent cracks on a more mature tree, there is no single reason for bark splitting on trees. This crack may have started from a wound inflicted earlier in the tree's development. Sometimes a crack may remain in the internal wood, but growth or other factors can cause the crack to expand and split the bark. Fluctuating growth conditions also cause splitting of bark. Hot, dry weather (which slows growth) followed by wet or ideal growth conditions (such as cool and rainy June) may cause a growth spurt leading to splits in the bark.

Little can be done to help the tree deal with this type of injury. A healthy tree will form what is called “wound wood”, which is essentially a callus that forms over the injury. Healthy trees callus over quickly. Encourage health by fertilizing (if needed) in the spring, proper pruning and adequate irrigation in hot, dry weather. Do not fertilize in the fall, as that encourages new growth which is more susceptible to splitting. Do not remove the bark around the crack or attempt to paint or treat the damaged area. Bark splits generally close over completely leaving a slight ridge in the trunk where callus tissue has been produced.

As the tree grows, the bark becomes darker and becomes slightly raised with long, flared plates with ridges. The appearance will likely vary in color with brown, gray, or near black, often with an orange interior bark.

Finally, one notation on this tree. It appears that it was planted incorrectly which has caused what is known as ‘girdling roots’ which are roots that emerge at or slightly below the soil surface. Girdling roots cut into at least one side of the main trunk, essentially choking the tree and preventing movement of water and nutrients. This tree may start to show symptoms of decline at some point because of this. See the photo attached notating the girdling roots.