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Swales and layers relative to the sun?

 
Dale Bunger
Posts: 45
Location: WI, USA (Zone 5) Continental ~33" avg. rainfall
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Hopefully, I am taking things too literally, but I am struggling with the arrangement of layers in regards to slope.

It seems like the ideal situation for swales and solar exposure in the northern hemisphere are at odds with each other.

My understanding is that the swales will stop the water and cause a saturated zone just downhill from the swale itself and that the berm that is created will actually dry out relatively quickly and is ideal for the shrub/berry layer.

It is also my understanding that the layers should be planted so that the lower layers are on the sunny side of the understory and canopy layers.

I tried to make a picture to show my thoughts.

Here is the sun relative to a Northern slope. It puts the layers in an ideal spot.



and here are the same plants located on a Southern slope. It seems like the berm would get very little sunlight once this is established.



I am confident that the berms will do a fine job of capturing and storing the water, but are their any suggestions for optimizing the layers on the Southern slope?
 
Paul Cereghino
gardener
Posts: 855
Location: South Puget Sound, Salish Sea, Cascadia, North America
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I am not sure that you need to have the emphasis on placing the understory species on the berm, or limiting a contour strip to the downhill side of the berm (although it is an advantageous situation in many climates). Mature root systems typcially extend 1.5 to 3 times the drip line and so a variety of positions will be able to derive benefit from the swale-berm effect. Also consider the potential for variation in canopy height along the berm rather than only across the berm. Then there is change over time... you might plant too dense, knowing you will thin over time (adding time as an element of the design), or some shorter lived fast growing canopy species might be subject to harvest or chop and drop to make way for other species. The permutations are annoyingly unlimited.
 
Rick Cobden
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Similar question
I have a piece of land in South East TX (usda 8B) of just over 10 acres – ave 50in rain year
I am considering 1.5 acres of walnut with compatible species below. With possible bee hives.
Land is very shallow fall from west to east of aprox 5ft over the lot. N/S length aprox 850, E/W length aprox 550
Options
• plant strips of Walnut N/S (giving a sunny side and a very shady side but pretty narrow in summer as sun angle is very high)
• Plant strips E/W (giving one side with morning shade, one with evening shade – larger partial shadow)=
• Swail N/S with Walnut on swail mounds i.e. strips N/S
• Swail N/S with strips of Walnut E/W some trees on the swail mound, some in the inter swail gap

Which orientation is companion plant optimal (assuming roughy 80 spacing between rows and 40ft between walnuts in a row?
 
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