Despite its name a potato clamp can be used for storing more than just potatoes, you can use it to store beetroot, onions, apples, pears,swede,turnips and flower roots such as gladioli and dahlias.
Instructions
First of all clear a patch of earth and dig a shallow trench (about 10cm/4 inches down), the area it takes up is dependent on how much you need to store.
Then fill this trench with straw and pile up your produce into a pyramid shape on top of it.
The potatoes, or whatever you are storing, should be pilled up to half the width of the clamp, so if your clamp is 1m across then they should pile up to 50cm.
Cover your produce with another layer of straw, about 15cm (6 inches) thick.
Earth is now piled up on top of the straw covering the produce.
And a trench is dug around the finished clamp. 
The earth covering should also be about 15cm (6 Inches) thick. A 15cm (6 Inch) ventilation hole (C) should be placed in the top of your clamp, and then filled with straw.
This is a cutaway picture of how the finished clamp should look. The clamp should be able to store your produce over winter, ready for next spring.
Other Storing Methods
Deep Freeze
If you want to store a smaller amount of potatoes then an old deep freeze is a good idea. This is not as it sounds (a big electric freezer) it is essentially a wooden box with a lid. Firstly put in a layer of clean dry straw across the bottom of the box. Then you add your potatoes. This must be undamaged, John Seymour recommends that you sort your lifted potatoes into three piles, perfect large ones for storage, smaller and slightly damaged ones for immediate consumption and the diseased, damaged and tiny ones to be destroyed.
You should put in a layer of about 30cm (1 foot) of potatoes and then add another layer of clean and dry straw. Another layer of potatoes can then be added with another layer of straw on top of that.
Put the lid onto the box (deep freeze) but ensure that you wedge it open with something that keeps the air in but is not big enough to let a rat in, a doorstop is ideal.
Storing Onions by stringing them
Again according to Mr Seymour (and I tend to agree) the best way to store onions is to hang them.
Firstly you should ensure that they have dried out simply leave them on the ground after picking them to do this. If it is wet then cover them to shield them from the rain but allow the wind to reach them. Two bricks and a bit of wood on top should do the trick. They take about two weeks to dry out properly, garlic is the same.
Take four dry onions and knot them together twist this around a piece of string. Now add one onion at a time to the string by twisting it’s stalk around the string, ensure each one is securely fastened to the string and that the whole bunch does not get too heavy. You now need to plait the knotted stalks around another bit of string, make sure the onions hang evenly when held up. Now tie the top of the string up in your shed or any cool place where there is plenty of air.
Storing Marrows, Squashes and Pumpkins
I never seem to have enough to store as they get eaten as soon as I grow them, but the best way apparently is to hang them in nets. However if you lack room they can also be stored on shelves if you turn them occasionally.
Beetroot, Carrots, Parsnips, Swedes and Turnips
Beetroot can be stored in bucket of sand as well as in a clamp. Ensure that the roots do not touch. Try and make sure that you lift them on a dry day as you can just brush the earth off them. Again like potatoes discard any that look diseased. Also you should twist off the tops but try not to damage the veg as you do this. The sand helps insulate each vegetable from the others incase of rot and also lets air circulate.
