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Using swales in pine forest

 
Thom Foote
Posts: 33
Location: Colbert, WA
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Here's my situation- 10 acres in pine forest, the forest floor covered in 6-8" of "duff" on a 5-20 degree slope. 17" of rain mostly Nov-March with some in April. Soil is fine silt mixed with a lot of fractured basalt. I am building small pondettes of 10k gallons each above my planting areas for future gravity fed irrigation and water storage. Forest duff does not allow rain runoff to occur. Duff absorbs and holds the rainwater. I would like to NOT have to pump my well water uphill to fill these and keep them filled. I need ideas about how can I build swales that will encourage and channel rain into these various pondettes? Scrape off the duff and create lined swales? Dig slightly sloped swales that lead to the pondettes and hope the water flows under the duff to them? I just don't think the idea of holding the water in the soil and building up the soil from the ground up is practical on 10 sloped acres of basalt. Help.
 
Mike Gaughan
Posts: 26
Location: Central CT, Zone 6
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Just curious...how thick is your soil, or in other words, how deep to bedrock? My initial thought is the prevalence of basalt chunks means your topsoil is thin and the bedrock surface is not too far below. This could pose a challenge with regards to water retention in ponds or otherwise, because basalt bedrock is often highly fractured and those fractures drain water away. The prevalence of pines is also interesting. Pines typically thrive in dry, well drained soils. Have you completed any ponds yet? What are the retention characteristics? What I'm getting at is that the duff may not be the limiting factor, but the site geology.

Also, that duff probably serves as natural erosion control. You might find your swales filled with a whole lotta silt if you scraped the duff.
 
Lyvia Dequincey
Posts: 45
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I hear you. I have pines on top of a knoll, and I need to use that area, but how? It is erosion prone with thin acid soil and windfalls. Here's my plan - collect dead wood and manure and soil to put some hugelkulturish piles in the low spots, and build soil first with green manure. Then eventually put more productive trees in those spots, like apple or hazelnut.
This might hold water better than a pond. Maybe a masonry cistern to supplement.
 
Michael Cox
Posts: 1575
Location: Kent, UK - Zone 8
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Did you see the recent thread about making a spring? It sounds like your soil/duff is naturally letting water infiltrate so why not see if it is naturally seeping back out again elsewhere (or if you can make it seep) and feed a pond.

http://www.permies.com/t/32725/sepp-holzer/Sepp-Spring-Terrace

Basically these questions can't really be answered without a better understanding of how water moves through your landscape. Do you have some impermiable clay layer? Is your bedrock impermiable?

Do you have a slope that groundwater will flow down? Are there any naturally boggy areas? What about seasonal creek beds?
 
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