[AlaninCarlisle]

Half of my Snowball turnips have clean splits. No rot or any other damage; just one or two large clean clefts in each one. Some turnips are tennis-ball sized and others are larger. Has anyone any ideas as to what may be causing this?

[RJR_38]

I don't grow turnips but I know if swede do that is normally due to uneven watering and they are the same family so I would go along that route...
Have you tasted any to see if they are particularly woody?

[compostqueen]

Dry weather. It won't affect the taste but it could affect the texture.  I think they'll be well edible though 

[Steveharford]

Yes I would think it is irregular watering too. I had it with some of my onions particularly some of the bigger ones. I got the impression that they had formed a skin when things were dry then started swelling again after some rain. I will just use those first.