A dedicated thread for irrigation Ollas

I love Ollas both for irrigation and for cooling water for consumption. This one is about the irrigation aspect, but I will make one for the other kind and link it later. So Irrigation Ollas are large, porous, unglazed clay jugs with a large surface area, large volume (ideally) and a narrow opening to reduce evaporation. They are buried underground with the top poking out and filled with water. The water seeps out through the porous clay walls and keeps the soil around them moist. They are very minimal water use and are a technology well fitted for desert climates. I do primitive pottery so I am going to make mine myself, but some people sell them, and some seal two terracotta pots together. Anyways please use this thread as a place to dicuss the use of Ollas as an irrigation tool!

To get the ball rolling... what are the material properties required for an olla? Fired clay is expensive at large scales and cracks under frost.

For example, why not build them out of pallet wood? I imagine a square tunnel that looks like an inverted "T" shape made of boards. Over a few years, this would break down and provide all the benefits of a hugelbed, and in the meantime you can water directly into deep soil layers.

Another idea would be to dig a trench, clad it with clay, then do a big charcoal burn, which as a side effect turns your trench into a semi-permeable irrigation canal.

Just some ideas off the top of my head, I would totally experiment with this if I had the land.

I have purchased some low fire clay to experiment with creating and utilizing Ollas. I have 'created' my first one but still need to fire it. The plan is to do a primitive fire to see if I can get it to set.

My current biggest turnoff is that they should be removed for winter due to frost heave. That seems to be a bit more laborious that I would want but still am going forward with the experiment.

On the topic of "wood" ollas:  I was just researching using bamboo as an olla.

My research suggests that bamboo is very good at holding water, too good in fact.  Some processing is needed for the bamboo to slowly pass water like low fired clay.  But.....

There are treatments to help bamboo take water based stain for things like furniture, so it is possible.

The shape of bamboo is so perfectly suited to irrigation, I am surprised it isn't already a thing.

Vitor Bosshard wrote:To get the ball rolling... what are the material properties required for an olla? Fired clay is expensive at large scales and cracks under frost.

For example, why not build them out of pallet wood? I imagine a square tunnel that looks like an inverted "T" shape made of boards. Over a few years, this would break down and provide all the benefits of a hugelbed, and in the meantime you can water directly into deep soil layers.

Another idea would be to dig a trench, clad it with clay, then do a big charcoal burn, which as a side effect turns your trench into a semi-permeable irrigation canal.

Just some ideas off the top of my head, I would totally experiment with this if I had the land.

One thing with low fired, non glazed, non vitrified clays is that they are very porous, but don't 'leak' that much unless the surrounding area is dry enough to kind of 'pull' the water from the pot. If the dirt surrounding the Olla is wet already, there is no force of osmosis and it won't continue to empty until the plants need it. I think that is the issue with most of the Olla experiments and alternatives is they don't function under the same principle.
About ground frosts; I never thought about them that much though I knew that they do crack and get destroyed in cold areas. My I live in Aus and my area is humid subtropical turning cool semi arid. Only minor frosts. We can grow broad beans, lettuce, brassicas ect through the winter, and its getting to warm for that to viable in future. It is still to cold for proper tropicals here unless pampered. I have bananas in my backyard that have successfully overwinted near the north face of the house. They just came of dormancy the last few weeks. I live above the flood zone in a big valley full of natural clay. I have the perfect climate for Ollas. I think that Ollas aren't feasible in cold climates other than very small gardens where they are dug up in winter.

What are Ollas?

In arid areas without winter frosts where once installed ollas can be left in place all year, they can be very effective especially used with mulch, though depending on the soil type and evaporation rate, more might be needed than expected. My main issue with ollas has been mentioned - in my hot summer/ cold winter garden using ollas would involve a lot of work as they need to be dug up and stored dry over the winter otherwise they spall very badly and disintegrate after a few seasons.  It's the same with unglazed terracotta plant pots.

Has anyone discovered good non-terracotta olla alternatives?

John C Daley wrote:What are Ollas?

An unglazed clay pot with large surface area and volume, but a small opening. They are buried in the ground, fill with water through thre small spout, and the water in the pots slowly seeps into the surrounding soil through the porous clay walls.

Anthony Breaks wrote:On the topic of "wood" ollas:  I was just researching using bamboo as an olla.

My research suggests that bamboo is very good at holding water, too good in fact.  Some processing is needed for the bamboo to slowly pass water like low fired clay.  But.....

There are treatments to help bamboo take water based stain for things like furniture, so it is possible.

The shape of bamboo is so perfectly suited to irrigation, I am surprised it isn't already a thing.

Sounds like deep pipe irrigation, but no pvc needed!
Drilling holes in the side of the bamboo seems to get around the issue of it not wanting to seep naturally, although it means it functions on a different principle to Ollas.  
An article on deep pipe irrigation: https://www.echocommunity.org/en/resources/c9b0359d-0adf-4485-af08-7f746c44514e