Source: https://wateruseitwisely.com/olla-irrigation/
Use of low-fired, clay ceramic vessels (ollas) is an ancient technique for the efficient irrigation of crops. First, in use in China and North Africa more than 4,000 years ago, the technique has spread throughout arid regions of the world. The use of ollas (pronounced oh-yahs) can save the gardener time, energy, and water. Olla users report that their vegetable gardens produce more lush plants with higher productivity. Plants watered in this way do not undergo stress cycles due to water and can live and produce longer. Ollas can be a relatively inexpensive way to maximize your garden output while minimizing overwatering, runoff, and water loss.
How it works
The principle is simple. A clay pot is buried with only the opening on top visible above the soil surface. It is then filled with water. The porous walls of the olla allow for water to dissipate into the soil as needed. Because the pores in the clay pot are small, the water does not freely flow out of the pot. A suction force is created by soil moisture tension as well as the plant roots. If the soil is dry, the water inside the olla will release faster as the soil roots “pull” it out. Likewise, if there is a recent saturating rainfall the water in the olla will remain until the surrounding soil dries. Therefore, olla irrigation is extremely water efficient and prevents excessive evaporation and water runoff.
It is also better for the root systems of the plants. It promotes deep watering and dense root growth which facilitates more efficient nutrient and water uptake. At the end of the growing season dig up your olla and you will see the efficiency of the olla in action. There will be a dense mat of plant roots. Compare with locations where ollas were not used and the difference is clear.
With ollas, soil and roots do not go through extreme drying and wetting cycles which is particularly beneficial to prevent bitter tasting greens, a challenge to gardening in arid regions. The consistent water also prevents cracks developing in tomatoes or melons which form if plants receive abundant and then scarce water. Additionally, with ollas the soil surface remains relatively dry in gardens which can prevent the growth of weeds and also helps minimize some unwanted insect populations.
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Clay Pot Irrigation – a simple adaptation of an ancient technique
Want to conserve water but still want to make sure you aren’t under-watering your garden? Want to establish a simple greenhouse irrigation system? Clay pot irrigation can save 50-70% of water without depriving your plants.
This is an adaptation of an ancient method of irrigation that is thought to have originated in Africa 4,000 years ago. It uses the porous nature of clay pots to allow osmotic pressure to suck the water into the soil where it is needed. People use beautiful fired pots called Olla with a narrow neck buried in the soil.
Unless you can make them yourself, this may prove an expensive solution so here’s an inexpensive and simple alternative.
Get hold of an ordinary 25 cm (10 inch) terracotta pot. Plug the hole with a wine cork. Bury it almost up to its neck in the soil but not too deep so that soil falls into the pot. Fill it with water. Add a terracotta lid.
Plant seedlings or sow seeds 18 inches around the base of the pot. Water will slowly seep out through the clay wall of the pot, directly irrigating the soil around the pot. As the roots grow they will wrap themselves around the pot. The plants takes up almost all the water, and because the water source is now in the ground, evaporation is almost nil.
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How to Make a Ceramic Olla Watering System
Potters know the pleasure of cooking and serving from hand-made dishes designed especially for homemade recipes; and every cook knows the sweetest peas and corn are those that are harvested fresh from the garden moments before they are to be eaten. To complete the triangle and bring pottery into the garden, you can make ollas to keep your thirstiest vegetable plants healthy and productive through the hottest summer weather.
An olla (pronounced oya) is an unglazed bottle made from porous clay. Filled with water and buried next to a garden plant, the olla allows water to seep slowly into the soil to be drawn up by the roots as needed. Tomatoes growing with an olla suffer less from cultural problems such as blossom-end-rot as they receive a steady supply of water. Cucumbers are less likely to grow bitter in hot weather. Pumpkins and squash can grow big and plump without splitting their skins. Ollas keep the soil from drying out but never contribute to overwatering—if the soil is moist enough, water doesn’t seep out of the porous clay. As long as you keep the olla full, the plants always have exactly as much water as they want.
For most purposes, a fairly large olla is desirable so you don’t have to fill it too often. You want a nice round bottle with a long, narrow neck so you can bury it fairly deep and leave the neck sticking out of the ground for easy filling. You can throw a bottle from 6 or so pounds of clay, trimming the excess from the foot as needed. Or, you can make a bigger bottle with less clay if you throw it in two sections.
1 Throw a wide, sturdy bowl. Cut the rim at a downward angle toward the inside, and measure with calipers.
2 Throw a second bowl to the same rim diameter. Open it up all the way to the bat. Trim the angle of the rim upward.
Two-Section Bottle
Start with 3 or 4 pounds of clay and throw a sturdy bowl on a bat. This will be the bottom section of the bottle, so don’t make it too delicate. When you cut the rim, bevel it so it angles down toward the inside of the bowl, then measure the outside of the rim with calipers (1).
With an equal amount of clay, throw a second bowl (this will be the top section), but open it all the way down to the bat, making an opening big enough to get a few fingers inside and leaving a generous amount of clay at the base. Measure the rim with calipers to make sure it matches the rim diameter of the first bowl, and bevel it in the opposite direction. This means it needs to angle down toward the outside of the rim. With the two cuts angled in opposite directions, they will fit together perfectly and make a more secure joint than two flat cuts. Don’t wire under either piece.
Allow the base bowl to stiffen slightly, so it can support the weight of the second section. Put the bat with the bottom bowl back on the wheel and pick up the bat with the second section. Flip it upside down, holding it by the bat so it stays perfectly round, and set it on the first section rim to rim, matching them up exactly (2). Use your fingers and then a stiff rib to smooth the two pieces together. Cut the top section free from the bat by running your needle tool under the edge as far as it will go, then cut it the rest of the way with a wire. Remove the bat.
3 Join the two sections together. Then, widen the opening to fit your hand and join the inside seam.
4 Create a neck by alternately pulling and collaring. You want the neck to be at least 3 inches tall and 1½ inches in diameter.
There will be a thick collar of clay where the pot was stuck to the bat. Use this clay to form a tall, narrow neck. First you need to make the opening large enough to get your hand inside to smooth the area where you joined the two sections (3). Next, pull up the neck and collar it in until it’s about three inches tall and the opening is 1½ inches or so in diameter (4).
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Videos
Broken Ground’s Kareen Erbe talks about Olla Irrigation, an irrigation method that will save you time, water, and money. For more Broken Ground videos on gardening and permaculture, go to https://www.youtube.com/channel/UCtSm…
