I am going to give this a go on the allotment this year. It's an excellent way of storing large quantities of root vegetables outside and is not often used today. If you don't have much space at home and lots of root vegetables then it's worth a go.
Clamping is just a pile of roots on a bed of straw and straw and earth on top.
Here's how to do it:
1. Choose a site that is unlikely to become waterlogged.
2. Harvest your root crops and allow to dry on the soil for a few hours.
3. To build the clamp, start with a good layer of straw. On top of this pile your vegetables in a pyramid shape.
4. It's also a good idea to dig a small trench around the base of the clamp to help draw off water.
5. Cover this pyramid with a layer of straw to leave for a couple of days to allow excess moisture to evaporate.
6. Cover the straw with a layer of fairly dry earth about 15cm thick. Leave a few tunnels with straw sticking through at the bottom and top to allow air to circulate. Smooth the earth flat so that rain will easily run off.
It's best to make a series of smaller clamps rather than one huge one. That way you won't waste time burrowing into a clamp and then rebuilding it. It's better to dismantle a clamp and then store sacks in a shed until the next clamp is needed.