Hi all. Hoping someone might be able to help me out with a question about swales and spacing between them.
Back ground. I am about to start a project site, near Tonasket, WA, in Okanogan county, state of washington. The property is 20 acreas, about 2200 feet elevation, on Palmer Mountain. Level to hilly terrain. Rainfall is between 14-16 inches a year, plus about 2 feet of snow. Rather arid, but not desert.
From what I've read and heard from videos, it is best to start at the highest point you can in the landscape. So this would put it up on top of a hill. From the top of that hill to the first swale, about how many feet down from the top should I start it?
Then, how far apart should the next swale be placed down hill from it?
Of course it depends . . . but a general rule is that you want to space swales the tree height apart. So if your plan to plant trees that will be 100 feet in the air, then you want your swales 100 feet apart. If you are planting trees that will mature to 15 feet tall, then dig swales 15 feet apart.
With that said, if your are south facing (northern hemisphere) on a slope then I think you can probably tighten up your distance. If you are north facing, then you want more sunshine to come into the space.
You can create lots of micro climates based on your spacing and texture of rocks, water, etc.
How far down depends, as close to the top as you can get and still capture meaningful amounts of water.
How far apart depends on what the end goal is. Tree height apart is a good rule for general food forest, further apart for alley cropping or silvopasture. But depending on the trees and soil, once you get more than 60-120 feet apart you start to lose the symbiotic benefits. So if you need more light for your crop, choose shorter trees instead of making the inter-swale distance too big. or shade tolerant crops.
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my fledgling understanding was that the spacing should be so that the tops of the trees on the next downhill swale should be even with the bottom or line of the first swale, to avoid shading issues. But on flatter lands that would put the spacing kilometers apart so then it becomes a question of how big you want the inter-swale paddocks/fields to be, without shading.
I think a lot of folks hinted at it when they answered tree width apart or some variant of that, but just a reminder "swales are tree growing systems". So space them swales accordingly. Take into account whether or not you're planning a savanna type system or a closed canopy, or a ... that will determine your spacing. Have an end goal in mind when you start your earthworks, that way you won't have to redo them latter.