Resting a field over winter prevents heavy hooves from poaching wet soil and destroying the root structures of dormant grasses. By keeping grazing animals off the land entirely, the pasture can recover undisturbed and produce a stronger, earlier flush of growth in the spring. It is a traditional grazing management strategy heavily associated with British hill farming.
Heard on the job
Keep the flock off the bottom field, it's winter-hained until at least April.