What fertilizer to use with swede

This year I am having problems getting swede established .  I have direct sown and also tried transplanting but they just seem to flop.  I have decided to have a go in a different bed where the overwintering onions have been.  What fertilizer would be good for the soil.  I have grow organic and chicken manure.  Thanks

My swedes have gone in after an early crop of beetroot.  The ground was manured last winter.  After the beetroot were out I weeded, dug over and scattered BFB then planted out young plants.  They seem to have got away OK