Posted: 29/01/2016 at 20:56
What is potato fertiliser, is it any different to a general multi purpose fertiliser?
Just a different NPK ratio pdoc. Farmers use roughly 1:1:1.5. You won't find that though, it will be something like 6-3-8, 15-13-19 or 14:14:21 just to confuse us!
Too much nitrate (N) will lead to overgrown greenery on top at the expense of fewer/smaller potatoes.
I didn't fertilize mine at all one year and didn't notice any reduction in cropping, but I'm on clay soil. Sandy soils probably do need it to get a good crop.
To answer James' question, I would never mix two different things like that, always apply separately and with a gap of a few weeks. Mixing lime and fertilizer, for example, will result in all of the nitrogen being released extremely rapidly (sometimes dangerously so) leaving little for later use by the plants when they need it.