Potatoes - how deep?

I decide to make a start with  my potato trial today, so I am using a black plastic bucket which is easily obtained      I have 5 holes around the base there is a piece of white paper sticking in one to show the level of the holes, I then put 2 scoops of soil in the bottom of the pail     followed with a half filled vending cup of 6X manure mixed in with the soil, next I put in the potato      then started filling up with wet torn up paper      
Will follow on with a record of setting up using paper and seaweed mix, still to collect the seaweed