Chickens for Ground Clearance

[Tarrel]

We're clearing some areas of the woodland ready for re-planting with coppice species over the 2014/15 winter. I have in mind putting some chickens in to do the work. The plan would be to use a moveable coop and to surround the "target zone" with electric chicken netting to keep out the predators.

The idea would be for the chickens to rough up the ground, clear some of the vegetation and add some fertiliser prior to fresh planting. In the spring I'd move them back to the same area to keep the new growth vegetation from competing with the trees. (Over winter I'll have them clear somewhere else)

Does anyone have experience of this? I have done some research already, but am seeking to add to the knowledge.

Two specific questions I'm looking for answers to are:

1. I'd like to have an area "dealt with" by the chickens in about a month before moving them on. Any idea of the "chickens per square meter" ratio that would be needed to achieve this?

2. I'd like to keep feed-input to a minimum. Again, any idea on the area per chicken needed for them to be almost self-sufficient if we are going to move them to fresh pasture after a month?

This will help me to know how many we need to get, and how big a coop will be needed.

All input, pointers, etc most welcome, as we've never kept chickens! Cheers.