We are new inductees to permies and are super enthusiastic about learning, but maybe a little behind on certain concepts. In other words, we need help understanding some things in Sepp Holtzer's Permaculture book. We don't quite know what he means when we talks about gradients in the section on terraces (p25). Can anyone explain this in a "gradients for dummies" manner?
We aren't sure whether the gradient refers to the angle of the terrace back into the hill or along the length of it (or either one, to be honest). And the ratios he gives (ex. 1:1.5 or 1:2) are also meaningless to us at this point.
Howdy Kate, It does seem to need a bit more explanation. The way I read it is that he is talking about the steepness of the hill, What type of soil you have, and how to build your terraces. If the hill side is full of rocks you can have a 1 to 1 ratio which means for every 1 foot horizontally you should have 1 foot vertically . So if your horizontal garden bed is 5 feet long your cut into the hill can be 5 feet tall. With sandy soil he says for every 1 foot tall you should have 1.5 to 2 feet long. so for a 5 ft garden bed your cut should only be 2.5 ft tall. I think I am doing that correctly?
I think he is saying that soils with rocks can be cut steeper than soils without them. I would also think that this has to do with erosion control. Bigger horizontal beds rather than taller vertical walls.
Sepp tends to bring his rocks to the top and leave them laying all over. I have built terraces by making the vertical walls out of stacked rocks. This helps hold the soil and adds heat at night to the beds.