Backup watering system

I have been thinking about building a garden using all hugelkultur beds with the aim of not having to water the beds at all by taking advantage of the ability of the wood within the beds to absorb water. However, a couple years ago in my area we had a very hot, dry and unusual summer - unusual now but I have read that it might be the norm for our area in a 20 or so years. Because of this I want to be able to have a backup water system for my hugelkultur beds. Now I could just use drip systems or overhead systems but both options don't really take advantage of the nature of hugelkultur beds. I have been thinking about using a system that I used in my old wicking beds - these beds had a pvc pipe system that allowed me to add water directly to the bottom of the beds. This worked very well and I rarely had to water these beds and the plants remained very happy. I was thinking about doing something similar with a hugelkultur bed - while building the bed I would put the pipe (with holes drilled in the bottom and weed fabric wrapped around it) in the bottom down the middle. One end of the pipe would be capped and the other would curve up 90 degrees so I could fill the pipe with water from a hose as needed. This would allow me to apply water directly to the core of the hugelkultur bed and take advantage of the ability of the woody material to absorb water. The wicking beds had a gravel reservoir to hold water and the hugelkultur beds would have a woody reservoir (later very rich soil). My thoughts is that I would only use this system if absolutely needed due to an extreme drought and most years it would all remain capped.

So, do you all think that this system would work for emergency watering? Would the water leaving the pipe cause erosion from within the bed? How long do you all think the pipe system would hold up? Could it be installed now and be good for decades? Do you all think this would allow for "recharging" of the hugelkultur bed during extreme droughts? Any thoughts on what diameter of pipe would be needed?

Overall, I'm convinced that hugelkultur beds can eliminate watering once well established and if large enough in my area but I also want to be prepared for those super hot and dry years that are going to be more common in the future. My view is that with climate change we need to have backup systems to help deal with possible extremes and this system was one that I was thinking about setting up.

Final note - I'm also planning on using other permaculture techniques such as swales, mulching/chop-n-drop, polycultures, developing landraces, etc. to help with my goal of not needing to water. But I also want to have an emergency system in place if all else fails.

Thanks all!

Well I tried it. It doesn't work as expected. Let me try to explain what I have learned by trial and error. On personal level: Istanbul has a weird climate. Yes it has all four seasons, but it also has a 11 year cycle. So like in every 11 years we are hit by drought for2-3 years which elders used to call "summer years". We also have "winter years" like the previous 2 years when we had up to 50% more precipitation as snow. So I have to take "summer years" into consideration.
Hugelkultur is kinda like dam reservoir and farmland combined. When the drought hits, prime goal is not fill the dam but to get some production going. Water is scarce, so you want to spend all the water to the plants. If you can fill the dam meanwhile, that is great. Also wicking beds are usually made out of plastic, so there is no leakage at the bottom. Hugelkultur on the other hand is open at the bottom, and mainly an above ground structure. I don't know how fast wood can absorb water, but it should be pretty slow. So if one wants to water a hugelbed, it should be really slow (or submerge the whole bed => last line), like drop by drop. Drip irrigation mimics it. It creates a moist blanket over the wood core while watering the plants. Also if the situation is worse enough to water a hugelbed, it means most of the soil has already dried out. There wont be chain of soil particles for the wicking action and to make things worse many types of soil become hydrophobic. They will just let the water pass. A moist blanket keeps the wicking chain intact.
I see you are in WA, so I would recommend drip irritation. You don't have to wait drought to use it. Also you don't have to put the pipes all over the bed, only at the top Ft or 2 is enough to water the whole bed.
One more thing to add to this topic for permies people closer to equator
Underground hugelbeds / buried wood beds are the antidote for sudden 1-2 year droughts if not more. burried wood beds

I would put it near the top, like on top of the wood after the first dirt is dumped and filling the spaces, but before the final dirt.

There are drip lines made to be buried, sub surface irrigation.

Thank you for the response and those are good points. I have a couple questions for you.

Likely a drought that would stress a hugel system would happen after the plants roots were fully established (mid-summer) which I thought would mean less need for the water to be pulled up through the soil by the interaction of the water and soil particles since the roots could access the water directly. Do you think this would work?

Also, I was assuming that the wood would have had time to decompose at least a fair bit before I would need to use this system. But even if it had not I would think the soil could absorb a fair bit of the water on its own. But if the wood had decomposed a fair bit I would think that it would be able to absorb a lot of water especially if I set it up the pipe to slowly release the water. I should note the soil I have here is very heavy in clay and would drain very slowly which would keep the water around the beds longer. My thought was to give a heavy subsurface watering (keep the water going for several hours) to help recharge the system - this would be done only once or twice through the drought. Does this change your thoughts at all?

I'm not a big fan of drip watering systems or any surface based watering systems as a response to drought. The main reason is that if you do dryland farming your plant roots will be trained to go deep but if you then apply water to the surface the deep roots are not being reached and the plants would instead spend energy on the surface roots which could undo the deep root training. This seems like it would make the plants less resilient not more over the course of the drought. Am I not understanding this process?

I'm also hesitant to use drip systems for the situation I outlined for a couple other reasons. If I had not already installed the drip system it would be very difficult to place it around a dense and established polyculture. If I did install the drip system at the start then most years it would just sit there unused and the extra work would be waisted each year. If I left it in place then it could degrade while not being used - my experience with drip systems is that they are not made out of the strongest material. The other reason is that a drip system would need to be used regularly over the duration of the drought since it would just be applying water to the surface. This seems to me that it would not be taking advantage of the nature of a hugel bed. What are your thoughts?

I should add that I did use the system I outlined in a traditional non-hugel raised bed in a much hotter and drier climate and it greatly reduced our watering needs. The raised beds were 4ft high and the pipes were about 3 feet below the surface. Now since the beds were not hugel beds we had to use the system during normal years. But it did work great for watering the plants and we only needed to water every couple weeks in the middle of the summer. Why would the system work in this setup but not in a hugel bed?

Also, all my hugel beds are partially buried with about half below the surface and half above.

Thanks again for your response and I look forward to yours and others responses to my questions.  

R Scott wrote:I would put it near the top, like on top of the wood after the first dirt is dumped and filling the spaces, but before the final dirt.

There are drip lines made to be buried, sub surface irrigation.

Thanks for the response - how long can those buried drip systems last before needing to be replaced? I was hoping to setup a system that could last for decades though I'm not sure if that would be possible.

There are different grades, but the shortest lifespan claim I have seen is ten years.

Vegetable roots were not sufficient to pull water 1-2 Ft in my case. The best explanations I came up is that: they don't have deep roots (more than 2 Ft) and air gaps form as hugel tills itself by time. Those zones get dry enough to air prune roots. So they never make it through actually.
I also have heavy clay soil. Almost pure red clay. Drainage was a big issue. I built a 4 Ft high hugelbed and it was over 1.5 year old when it got tested. Dried out pretty quickly. I thought that I did everything right while I was building it so I tried to come up with a new design. (Later on I figured out why it failed, I didn't alter wood and soil layers. It had only 4 layers and there were gaps in the core. I mean big ones. Dismantled and built a proper hugelbed with a drip irrigation on top, works like charm). In 2013 I built that new idea (please see the picture). It had a reservoir at the bottom. I filled that zone with wood and soil. I put a pipe to directly fill it. The above ground part was 2 Ft high, with a lot of soil and wood to aid wicking. Since I am living on a hillside, I needed a flat are to work on. So it is a table top design. It did work, but more like 30-40% efficiency. Then it started to settle, gaps formed again with some help by critters. I waited the system to respond, it didn't for 2 months (creating dry air gaps). So I filled the reservoir multiple times, but it also didn't help at all. Finally I installed a drip irrigation system all over the top to rescue what was left. To my surprise, when the wet blanket was formed, hugel started to work again. But this time I was not watering from the bottom. This winter I built a hugelbed with a reservoir and a pipe to fill it (5ft above ground 3 Ft below). We will see how it will respond. To create an artificial drought I will cover it with plastic in April-may and winter when it matures. But meanwhile, with the idea of "what if plants were able to reach the reservoir themselves" I built a similar design with only half a Ft above ground. I filled it twice while I was slowly building it, but never later on. It is working with no irrigation for the last 2 years. So to my experience, when drought hits hugelbed with a drip irrigation on top gets a big candy, table top hugel with reservoir gets "yeah that was ... fine..", and buried wood beds get a a round of applause.
So why am I building a hugelbed with a reservoir? Curiosity killed the cat, but satisfaction brought it back (:
What I understand from drought is a bit different I think. If there is a sudden drop of 20 or more % of precipitation that is drought (PNP). When it hits I don't know how long it will last, I don't know how hard it will hit. If plants are trained beforehand, I will drip irrigate  far in the root zone to keep roots healthy. If not, right under the plant. 20% can be dealt with good practice, 40% or more will definitely kill no matter what. All I ask for the production is to go on. Personally I would not try to modify their behavior when hit.
I am using the same drip-pipes on the same bed for the last 4 years with no issues.

I am building my first Hugelkultur planting bed, and am designing a Grey Water Irrigation scheme.  The grey water tanks are in the cellar, and all water from sinks, tubs, and washers flow into the vented holding tanks.  A motor operated valve allows me to control the water flow in a number of ways.  (Note:  I am a specialist in building automation and control.)  The water will gravity feed to the bottom of the mound, and will fill the trench that holds the logs and branches, and wood chips.  I have read through this thread with interest, and will take special care when layering the dirt with compost and grass / hay / straw and potting soil and manure and cardboard.

I am not sure how deep to dig the trench.  I was planning to have a shallow trench and to build up above the slope of the ground, but now I am wondering if I need to dig down deeper.  I had not considered the possibility that the mound might dry out.  There is a black tube running inside the large pipe that will allow me to pressurized a sprinkler, and I will probably water the mound from above in the middle of the night when I will get maximum soaking action and minimum evaporation.

Based on the sketch in the thread above, do you think that my trench needs to be deep enough so that the whole log sections are completely below ground?  I do plan to line the trench with plastic, and so will eventually have a pool under the ground that will be able to saturate the slowly decaying wood, but I do not want to place too much hope in the wicking action of the plant root system.  I will attack it from below and above in order to maintain the right balance.

Phillip Stuckemeyer wrote:The grey water tanks are in the cellar, and all water from sinks, tubs, and washers flow into the vented holding tanks.  

Everything I have ever read said grey water should never be stored.  Can you explain how you are doing it without the associated problems?

There is no doubt that the grey water is very stinky.  It is almost as bad as black water.  I have a 2-inch vent pipe that goes outside, up the wall, and vents under the roof overhang about 12 foot in the air.  Originally, I failed to put a 180 degree elbow on top of the pipe, and when the pipe filled with rain water the stink filled the cellar.  I have now fixed that problem, and there is absolutely no stink in the cellar at all.  I also placed a fan inline with the vent pipe, but since I installed the elbow I have found that I do not need to use the fan.  The fan is there just in case I have a problem, but I have not considered how to detect the stink with a sensor and to automatically activate the fan.  I suspect this would be a manual process, and really do not want the additional electrical load that would come with a continuously running fan.

To be honest with you, I plan to keep the valve open at all times during the growing season, and the tanks will only fill up in the event that something goes wrong, such as the pipes freezing.  I have two industrial bladder containers (IBC) with a total storage capacity of about 550 gallons.  I simply do not want all that grey water to flow to the septic tank.  I do need to manually drain it once a week in the winter, but I have piped it up so that it is simple to drain it onto the ground.

The typical farm has lots of interesting smells!  Grey water is not that bad, in the bigger scheme of things.

I also have a huge concrete cistern in the cellar (4 ft wide, 4-ft deep, 30 ft long) and new gutters and downspouts will be installed next week so that I can begin to collect rainwater.  That will be a great backup!

I'm much more concerned about what the smell means.  Oasisdesign.net has a lot of really good information on greywater systems, this quote from their site "Error: Storage of grey water
Storage rapidly turns grey water into blackwater (see photo, page 4). The word "storage" should immediately sound an alarm, as should anything that includes a tank bigger than 55 gallons (for residential systems). If you doubt this, just fill a bucket with grey water and observe it as it progressively darkens and becomes more fetid. Bacteria multiply to blackwater levels as well, at least the indicator bacteria."

It goes on into more detail but you get the idea.  I don't want to sidetrack the thread anymore than I have, but it's something to consider.

Yes.  I have read the OasisDesign website quite extensively.  As I stated above, when the pipes are not frozen my plan is to keep the valve open all the time, so any water entering the tank will immediately flow out to the planting beds.  The tanks are really for temporary storage when it is not practical to send it to the planting beds.  I have outfitted my tanks with the standard fittings that you find on a Recreational Vehicle so that the tanks can be easily drained and back flushed when needed.  However, if the tanks can hold the grey water with no leakage and no smell, then there is not a big problem that requires a solution.

My Hugelkultur / Keyhole planting bed is almost ready for spring planting.  Here is a picture that shows the various layers, all in a pond that will be continually flooded by the Grey Water system.  Still need to add a layer of Cow Manure and a layer of Potting Soil.

At each end of the circular trench / pond is a grey water flooding source.  The plastic sheeting passes below an outlet elbow and maintains approximately 8 inches of water in the trench / pond thus ensuring that the logs, branches and twigs at the bottom of the Hugelkultur mound remain saturated as the mass of wood slowly deteriorates and turns into a huge wet sponge.

Since the keyhole planting bed is built on a hill, the pond is a bit deeper on the downside.  It is very difficult to get the circular trench perfectly level, but I got pretty close!

My first Hugelkultur / Keyhole planting bed is almost done.  It is March, and I will be ready to start planting in April.  I have added the final few layers of soil to the bed.  I have attached a picture showing the latest developments.

The Gray Water irrigation system is also nearly complete.  I think I have worked out most of the kinks, and it is flowing smoothly.  I have posted the most recent picture to illustrate how it works.  The amount of Gray Water that my home produces is way more that is needed by a single planting bed.  I have room to build 4 more Keyhole gardens like this first one down the hill toward the pond.  The plan will be that the overflow from the highest planter will flow directly down the hill to the next planter, and eventually will exit the 5th planter and empty into the pond.  I hope this works!  Give me a few weeks / months and I hope to be sharing pictures of a bountiful crop!

I have now planted my new hugelkultur mound, and am watching every day as the seeds start to sprout.  The mound is nourished from beneath (a pond under the mound is continually flooded with grey water) and above (a sprinkler applies well water or rain water for 20 minutes three times a day) and this approach really seems to be working.  I have carefully planned the layout of the mound so that each plant is nearby to other plants that are friendly companions.  Here is a slide that shows how the plants are arranged in the planting bed.  There is plenty of room available for intensive gardening, but I am waiting until what I have already planted sprouts so that I do not overdo it.  Your suggestions are appreciated!

I must say that I am beginning to worry about growing vegetables in the Hugelkultur mound.  It is only about 16 inches down to the greywater that is pooling up under the mound.  As the log sections and branches rot and transform into a huge wet sponge, the mound will feed moisture to the roots of the plants as they reach down for a drink during the hot summer.

If I am using biodegradable soaps, will there be any risk?

How about the use of bleach in the laundry washer?

Any issues with bacteria?

The sprinkler above the mound allows me to water the plants 3 times a day with well water or rainwater, thus reducing the need to reach deep for water.

I am not sure if there is a possible health consequence.

Any ideas?