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wicking beds; pros and cons?

 
Gilbert Fritz
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Location: Denver, CO
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I am thinking about doing some wicking beds. What are the pros and cons? Can soil ecology successfully develop in these things? Would I be better off with a mulched garden and encouraging roots to go down?

So far, I know that cost is a con, water saving is a pro.

What about running water full of duck manure into one of these? Or grey water? Would these water sources be successfully and safely used? Or would it go anaerobic and cause lots of problems?

I could see these as sort of like small scale chimampas. If I build them up on gravel foundations in the shallows of a pond, would it work? Of course, keeping the water level constant would be difficult.

I have thought of inserting some sort of float down a rod into a watering tube in a wicking bed. A rod would rise from the float, and have some sort of figure on the top. When he disappeared into the tube I would know it was time for more water.
 
Mike Hoag
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forest garden urban woodworking
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We have some of these. For two years, they haven't required anything more than surface watering for establishing seedlings, and they haven't had any disease or pest problems. We used clay from our own sub soil to make the underground pond liners.

No need to overdo the inputs on these, just do the maths and make your "ponds" able to hold the amount of water you think you need. In our case, I wanted 2 months of drought protection, so our "ponds" hold enough for 1 inch/week/ for each square foot, with the course compost added.

We used our own clay subsoil to make our liner, so it required no additional cost.

The "ponds" sit down beneath double-dug "raised beds," at a depth of 2-3 feet below surface. The soil level is raised about 10" above grade. This gives lots of room for roots to expand downward. In fact, I'm sure it's excessive. In our case, we positioned them on contour to harvest enough water to fill the ponds in a small rain. Basically, they're "swales-plus," with the ability to bank a small reserve.

The "cons?" Lots of work. I'd only do this for intensive zone 1 plantings.

As one more thought, I would love to see someone do a temperate version of a "banana circle" on flat land with very dry sandy soil, with a circular wicking bed in the center of the circle. It could essentially be a hugelkulture, with a pond buried a few feet below the surface... trees planted at the edge of the circle to keep their feet dry, but allow them access to water reserves.
 
Abe Connally
Posts: 1502
Location: Chihuahua Desert
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a "pro" we discovered this winter is that these beds stay warm because of the thermal mass of the water and wet soil. We have peppers and tomatoes that survived the winter (they are still alive now) that are in wicking beds. Their counterparts in regular soil died in November.

So, if you have frost sensitive plants, you can plant them in a wicking bed, maybe cover with greenhouse plastic, and then fill the bed with warm water for the really cold nights.

 
                    
Posts: 238
Location: AR ~ozark mountain range~zone7a
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One 'Con" about the wicking bed is if your garden area is not level, like mine is on a 5% grade...which doesn't seem like much at first, till you get to digging... and figure out that one end of the ditch might be 1 feet higher than the other end. I ended up putting a StepDown about halfway of the ditch to give two different water levels in one ditch. I used a plastic liner in the bottom & sides of the ditch. A log or wooden rail at the top edge of a ditch can make the plastic liner easy to staple to

Another 'Con" is if you have large tree roots in the area, I decided against additional in ground ditch type wicking beds in the tree dripline area...because I don't want to harm the nearby big old tree roots (figure 15-25 feet from the base of a big tree)

A 'Pro" expect your wicking bed to become completely filled with spring rain, figure out your overflow point while building it. Mine will fill the ditch, stepdown to the lower ditch, then overflows into a big new hugelpile.

A 'PRO"...wicking bed is good place to bury a bunch of extra rocks you may have laying around. A ditch 30' long, 1' deep, and 1' wide...filled with rocks will hold in excess of 100 gallons of water, if you have a pipe(s) in it, it will hold more water.

james beam
eureka & snow feb2014 005.JPG
[Thumbnail for eureka & snow feb2014 005.JPG]
a nearly level wicking bed ditch
 
Abe Connally
Posts: 1502
Location: Chihuahua Desert
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james beam wrote:One 'Con" about the wicking bed is if your garden area is not level, like mine is on a 5% grade...which doesn't seem like much at first, till you get to digging... and figure out that one end of the ditch might be 1 feet higher than the other end. I ended up putting a StepDown about halfway of the ditch to give two different water levels in one ditch.


I'm in a similar situation, and I make mine small, usually about 10 ft long. That way, it's easy to level them without digging out half the mountain!
 
                    
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Location: AR ~ozark mountain range~zone7a
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That's right Abe, as you know the water level will insist on being 'level', and it is definitely something to consider...when we are digging by hand.

Here is a shot of the first one I put in last fall, the foreground is the hugelthing which will receive the overflow. I'm using run-off from the house & carport to fill my wicking beds. I don't expect to manually carry nearly as much water as I have been in the past, but I still have a good supply of water stored up in jugs & barrels.

This example received the StepDown at about the halfway point of the ditch, as you can see in this example one end of the ditch is at least a foot higher than the foreground= alot of digging! LOL Oh well I have nothing better to do.

james beam
wickingbed 009.JPG
[Thumbnail for wickingbed 009.JPG]
 
Abe Connally
Posts: 1502
Location: Chihuahua Desert
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we try and keep ours on contour, and that helps a little bit, ours are usually about 3-4 ft wide. 10 ft is the longest we've been able to make one, though, cause they start getting way out of level and require too much digging.
 
Laura Denyes
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I built my first wicking bed this past summer as part of a larger permaculture garden design for an organic preschool in Cave Creek, AZ. In our situation, the pros were considerable since water conservation is of enormous importance in the valley. We do not need the thermal insulation for the winter, nor is it of concern to build for an overflow area since the desert will wick that away in no time if there is a flood. The slope of the land allowed for a natural runoff area as it were to the rest of the garden, in the case of the 30 year flood, with considerable swale and berm footpaths, irrigated basins on the slope and french drain style catch-all along the lowest edge.

Pros in the desert allowed for a larger scale evaporative cooling effect on the roots, an upgrade from the use of ollas.

Considering the only wicking bed demos I'd viewed prior to construction were 5 gal bucket or kiddie pool sized, this wicking bed area was rather large and was built as a demonstration/learning garden for the kiddos. Conveniently, the excavation of the basin for the wicking bed also prvided our native soil for the construction of the cobb wall!



As per your question about duck pond water... I wouldn't! Unless it was in very controlled smaller doses. I will stay tuned to see the science behind a solution for that, should I be way off base in my instincts.

And I concur about the hiding place for excess stone/rock!
 
                    
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Location: AR ~ozark mountain range~zone7a
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Some "After" snapshots of wickingbeds, just about ready for this years gardening.

james beam

2wickingbed 001 (2).JPG
[Thumbnail for 2wickingbed 001 (2).JPG]
upper wickingditch
2wickingbed 002 (2).JPG
[Thumbnail for 2wickingbed 002 (2).JPG]
lower wickingditch
 
                    
Posts: 238
Location: AR ~ozark mountain range~zone7a
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A 'Con', either have the deep depth of dirt (like 8"+) above the wicking substrate or expect to use a thick layer of mulch, as the wicking action will cause a good amount of water to evaporate from the upper surface of a thin layer of dirt. This summer I opted for a thin layer of dirt (3-6" ) {I only have so much dirt available}and I didn't use leaf mulch or any kind of mulch, the dirt stayed moist as long as the water in the ditch held out. But as the summer heat came in, both ditches I built were eventually depleted with water, from evaporation, next year I'll probably have a thicker dirt layer over the wicking ditch and definately a thick amount of leaf mulch to use around the plants within the wicking zone.

Another 'Con', is I was hoping for the wicking action to move laterally to surrounding growing areas. I did get 12-36" lateral movement of water beyond the edge of the wicking ditch, but only in the downhill direction, the uphill side of the wicking ditch remained fairly dry.

A 'Pro', moisture loving plants like Gourds & tomatoes thrived quite well with no 'daily hand watering'. And weeds pull out quck & easy, earth worms seem to thrive in the wicking ditch moisture zone. Refilling the wicking ditch was easy, just direct the rainwater into the ditch. Sandy-ish well drained dirt is probably better over a wicking ditch, than heavy clay-ish dirt, as the roots should not remain waterlogged from the consistent water source.

james beam

 
James Slaughter
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Around 6 years I did the hard work of preparing a water wicking bed (raised sleepers, pond liner, ag pipe, gravel, geotextile fabric) and made a few errors that others may learn from.
#1 - Make certain your entire pond liner is above the external ground level, especially if you have any large trees nearby (my casuarina sends out roots in at least 15 mtrs in all directions...).
#2 - Beware of compaction - as it's not exactly designed for digging. If I were to do the project again I'd go shallower soils and use less straight dug soil in the mix, or preferably even only use potting mix like materials.
#3 - Make certain that slugs and snails can't access your watering area - they tend to use it as an ideal habitat for breeding.

All in all, given the work required and the potential for effort in maintaining it, I would no longer recommend them. I think that a more viable system with less potential for headaches is the "Rain Gutter Growing System" of growbags / pots in a pond / kiddy pool. At least then you can see if anything is going wrong with the water reservoir (drainage, water level, etc) and maintain the soil structure your using to grow in (a "compost tumbler" being a good way to remix and freshen up old material).

 
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