spacing of swales

Hey Darren,

Per Cassie's daliyish email: I had a question on the spacing of swales. Geoff Lawton quotes using the canopy of your climax species and their max height should be the base of the uphill swale, unless you are on flatter ground (like I am). Then he talks about being able to bump the prevailing winds up to keep them at canopy height.

My issue is that the prevailing winds are parallel to the contour lines so I'm not sure how to space my swales.

I assume with the situation I'm in I just have to think about maximizing irrigation efficiency but i'm not sure what distance intervals would do this. I have sandy clay loam soils at 6200' elevation in western Colorado usa (cool to cold temperate, high desert ish area.

Any help is appreciated.

I think sunlight energy is more of a factor than wind.
I would think that you don't want your tallest trees at maturity to shade out the swale behind it unless perhaps you want to tone down a fierce sun in a hot climate for the hottest part of the day.

I'm most worried about irrigation to the hay that is spaced between the swales. In my preliminary design the swales were spaced at around 150' to 200'... is that too much space to allow the swale to irrigate the downhill portion up to the next swale?

A factor we used in determining spacing of our swales was the size of the potential equipment we could efficiently use between the swales if we wanted to bail the forage between them. You don't want to run equipment three times up and down between swales when that third pass is only 1/2 the width of your machinery. I realize not everyone is using equipment on their places, but I often like to think of larger scale options. So, the space between our swales was a multiple of full passes of our equipment. There is some fudge factor because not all swales are exactly parallel and that causes some inefficiencies. But, it was a general rule for our swale spacing.

A correlative example for some permies would be the swath of their scythe mowing. You don't want to do 2 and 1/2 swaths if you can help it, right? You'd want either 2 or 3 to be efficient.

What size swathers were you running 20'? I'm on 80 acres down here and i have 300 up high so I'm attempting to figure out large scale swales with grass/alfalfa haying inbetween. I think the upper end of what people are running out here is 18-20' swathers.

Ryan, we're a bit smaller scale than you. But, so glad you're applying this to broadacre.

With that said, we had (when we cut our sales) a Ford 8N tractor with a 7' sickle-bar mower. Our swales were generally set for three passes with this equipment set up. Sometimes the contour tightened that up a bit. Love to see your design for your property, Ryan. I'm one that is really not happy about haying and would much rather mob graze through those in a silvopasture approach. But, in case I did have to cut it, I wanted the spacing to be conducive to that.

Ok so my swales might be on the scale of 10x larger than they should be lol. I'll see if anyone else has time to chime in on spacing for water efficiency. If you want to PM me your email i'll send over the sketchup file I have. Its a bit rough around the edges but decent to fly around on. I'm always interested in hearing criticisms or different ideas of things to do.

Implementation will end up being the hard part . Need to make sure I understand all swale species and spacings and then gather all my pennies into one corner to give away to excavator operators .