Hello,
A first post here. First an intro, then a plan summary, then a question. We have a small homestead (7 acres) that we have a cider orchard started on (Don't Quit Yer Day Job Orchard) and are finishing our house. What fun to raise children, build a house and try to farm at the same time. Really though we are blessed with all of it. We have several acres on a sloping hillside that was logged about fifteen years ago. Currently it has some usable timber for lumber, and of course we will use everything on it in the hugel beds once we get the swales made. The summary of our plan for the first part of land to use the swales is to install the them, plant fruit trees, understory plants, and then get those going for at least one year before bring the pigs into the area. Also, we plan on only about four pigs maximum on this two acre area. Not sure if we'll section it off into smaller paddocks but that would seem likely. The goal of feeding the pigs is that once the trees are producing we will be sharing much of the fruit with them. I think Sepp would be pleased.
Here's the question, eventually: in his Permaculture book, Sepp goes into how swales alone are fine for gently sloped terrain but on steeper terrain you'd be looking at forming terraces, then installing swales on the downhill side of those. Considering that, I'm interested in asking someone here who is experienced installing terraces and swales who knows what percentage grade is sort of a recommended practice for installing these terraces. I understand that each site is different as are soil and rock combinations. I should also include that where we're at here in Appalachia, zone 6b, we have a a lot of sandstone "tumbling loam". There is a lot of rock and while we get 45" of annual rainfall (excellent), the rocky soil drains pretty well. How well I couldn't tell you. Rainfall does run off at a certain point as it sometimes rains for d-a-y-s. A good problem to have. All the more incentive to build a good system for water retention. Really looking forward to it all.