http://imgur.com/zQLvKdr,17K8T3H,DyEurp7,UgrjPcj,7AMHkxP#4
Pics uploaded to imgur
I'm planting a food forest on a slope and I really wanted to have the trees on berms.
You can see the first pic has the slope before the swales, you can see contour because it was subsoiled on contour.
I've wanted to have some swales for some time but don't have machinery or resources to bring in a bobcat or a backhoe.
So I brought in a tractor with one of those plows used to dig drenches. I marked out stakes on contour for the guy to follow and told him I wanted him to go on contour. He was surprised because here everyone makes downhill trenches to pull heavy winter rains off of their land. I don't think anyone has done swales here for 50 miles around me or maybe more. The closest swales I've found were in Asturias.
I live in a wet area, but summers are dry and I live on a well-drained slope, so after weighing pros and cons, I decided to go for it
The swales are about two-feet wide and 20 inches deep (60cmx50cm). The issues is that I usually see that swales are considerably wider than they are deep and they have a gradual slope on the backcut, I always see 1:3 and these are very vertical.
If you look at the labeled photo, you can see the tire tracks, some uncompacted soil and then it drops off very steeply. My experience with the soil here is that when it has been plowed, it is very fluffy and absorbs lots of water when it rains but eventually the rain compacts in back down and it kind of seals. So, I don't think the tire track soil is going anywhere, I'm using the tire tracks as paths on contour, which is nice to have.
I'm filling in the swales with branches and brush at the moment and I'm thinking that if the loose, uncompacted soil erodes in to the swales, it will mix with the wood and create some impromptu hugulkulture. I am going to continue filling the swales in with organic material.
I'm sure I've made mistakes but I still have some nice berms to plant trees and if I fill the wales in with organic material, at worst I'll have some very high levels or organic matter in the soil next to the trees and some better rain absorption for the dry summers.