DigitalVinyl said:

http://members.aol.com/digitalvinyl66/radish-burst.jpg
Radish, small, round red Altaglobe (28 days)

Just pulled the biggest radish I had to check it. The bottom is split
and spreading open. It was in about 27 days from sprouting. I also
thought this variety would be a little bigger than this. They do
describe it as a large marble, while I would say this was an ordinary
marble size.

Does this mean it was too long in the ground?
A watering issue?

Uneven watering can cause it. The more mature the radish is, the greater
the likelihood of splitting.

Boron deficiency can also increase the risk of splitting. Thin, misshaped roots
will also be seen with a boron deficiency.
--
Pat in Plymouth MI

Any technology distinguishable from magic is insufficiently advanced.
(attributed to Don Marti)