crop rotation problems

[Si D]

I'm trying to work out the planting areas for next year so that I know which bits need manuring over winter. 
first problem is that every book I look at seems to have different members in each of it's groups.

Second, and biggest, problem is that I grow more potatoes than anything else, in fact in terms of area used they ought to be in a group of their own.  How do other people who grow lots of spuds get around this problem?

For what it's worth, the stuff that I am trying to organise is:
potatoes
swedes
parsnips
turnips
carrots
sprouts
broccoli
peas
runner beans
onions
leeks

which seems to fall into the following groups according to several books:
Roots: potatoes, swedes, parsnips, turnips, carrots, onions
Brassica: sprouts, broccoli
Legumes: peas, beans.

and thus the 'roots' group is several times bigger than any other group and it's difficult to see how I'm going to arrange things without growing stuff from the same group in the same place for two or three years.  Indeed, the potatoes alone take up more space than the legumes and brassicas put together.  And that's not to mention the problems of not being able to dig the potential potato beds because there is still stuff from last year growing there!

any help, suggestions appreciated!

[Si D]

[ceres]

Swedes and turnips are brassicas so that evens things up a bit.  Also, you can't treat potatoes and roots together.  Potatoes need manured soil, roots don't.  Onions and leeks are a separate group - alliums.

 

[Tee Gee]

This link  might help;

http://www.thegardenersalmanac.co.uk/Data/Crop%20rotation/Crop%20rotation.htm

[Si D]

thanks all, esp. Tee Gee: that makes it all a lot simpler!