Hi I want to use a chicken tractor in my garden and in an orchard. A friend, whose family kept chickens on a more commercial scale, said he's seen nearby chicken pens kill grown pine trees. Anyone know anything on how close/how long a pen(because we will probably have a pen too) can be to a tree or in a garden plot before it damages the soil? I know a stationary pen would be bad for the soil, but what about a moving tractor that may move every few days or something? With maybe 6 chickens?