Have you looked at the potato growing information at the Santa Clara
County Master Gardeners website? They have a good way of growing
potatoes in a half-barrel where you can use packaged soil and not have
to worry about these issues. Also, potatoes can be prone to certain
plant diseases that can make the soil unsuitable for other crops later
(such as strawberries). Using a half-barrel should avoid that problem.

I suggest using their pile method--a half barrel with a wire cage over
the top that you keep heaping straw upon to create a higher and higher
stack throughout the growing season, that becomes rife with potatoes.
The wire cage keeps the straw from falling off--anyway the details are
at their website.