At our allotment association quarterly get together a couple of weeks ago we had an interesting presentation from Selwyn Richardson, soil scientist & ex-agricultural adviser. Selwyn handed out a really useful guide for anyone who wants to understand how to feed their veg properly.
I've managed to get a copy of the guide. To download a copy go to my web site below & click the link under the Welcome! section on the top right.
What makes the guide so useful? It not only explains the major nutrients that vegetables need, but gives the content of these in various manures (including whether spread autumn or spring), the spread rate, when to apply on a 4 year or 5 year rotation, and if you're not doing things organically how much nutrients to apply directly.
Selwyn said he buys his nutrients (e.g. nitrogen) from Garden Direct (
www.gardendirect.co.uk)... he recommended against such things as Growmore ( weak fertiliser, high price) or seaweed (little nutritional value). Happily he gave me another reason to value my chickens... they produce by far the best of the manures he listed.
Hope you find the guide useful. John