Filling cracks in wood, but with what?

[bellman83]

Tingeling, I'm going to build a wide staircase in three steps. The steps are ash planks that will be about 320x3400 mm in size and 50 mm thick.

I have the planks drying indoors now and they have cracked a little in the middle at each end.

Attached is a picture of the worst one.

Either I leave them as they are or I consider filling the cracks before I sand the planks and cut them to their final shape.

Does anyone have any ideas on something suitable to fill the cracks with?
Preferably wood-like and not epoxy like in all the table-building clips on YouTube.

 

[Bjerke88]

Linoljekit maybe.

 

[bellman83]

Linseed oil putty maybe.

Yes maybe, I'll have to look it up.

 

[ArneTW]

Rout/saw and then glue a strip of wood into the groove.

/ATW

 

[Microkatten]

There are several options, e.g.:

1. Obtain wood that is dried without cracks or large enough pieces to cut away the drying cracks

2. Split the wood at the cracks, plane and glue together

3. Smaller cracks can be filled with wood glue mixed with sanding dust from the same wood. This becomes an almost invisible repair.

 

[bellman83]

Searing and inserting a piece feels the most professional, but the idea of wood glue and sanding dust is probably more suitable for my level of ambition.