Well keyline plowing goes back to black and white photos, the wallace plow was the largest selling agricultural implement in Australia in the 80's. In regards to how much or how little they work well there's to many factors to make some sort of salesman's pitch about it, hillside vs valley swales on an on. I was mainly looking at what most
permaculture enthusiast fail to be logical about, the downsides that can produce failure and swale blowout's is addressed in detail in the G.Lawton B.Mollison
pdc, There's allot that if you overlook something as simple as a
cattle track above your swale is
enough to blow out the walls in a serious storm which nobody can say doesn't occur in their situation. If you want to wet up ridges a keyline rip line is just enough water, but I wouldn't send a 1 meter wide 12 inches deep swale full of water towards 1 singular point in a swale. Swales don't work if there not level they just become a drainage ditch, the best of both worlds seems to be more of the worst of both downsides. If only the
land underground was as uncomplicated as the academic presentation on how water will infiltrate soil.