Certified GKH Gardening Expert
Are you seeing cracking on the bulbs or by splitting do you mean the terminology for pulling the bulbs apart?
Splitting and dividing bulbs is the same thing. Just some people refer to it one way or the other. Dividing/splitting tulips bulbs can result in a better bloom from the flowers as they will have less competition for nutrients in their immediate area. That being said, many people who have tulips that successfully rebloom year after year are often hesitant to divide their tulips because tulips need a very specific set of conditions to bloom year after year and dividing them can upset the balance they have found.