“Ollas for Irrigation”—2012, Ceramic and Print
Ollas are ceramic vessels used for irrigation. They are ideal for environments of water scarcity as they prevent evaporation, runoff, and spillage of water. When the unglazed ceramic vessel is buried in proximity to plants, the roots of the plant will draw closer and envelop the vessel, eventually drawing water directly through the ceramic, so no water is lost to the soil. This provides targeted, consistent irrigation of crops with little maintenance.
I created a small pamphlet to be dispersed in conjunction with ollas as devices, which explains in detail how they work, why they are an excellent option, how to make them, and how to design a garden bed around their use. The addition of a stopper prevents evaporation and contamination, allows the interior water level to be checked, and adds a decorative element to these garden devices. Though an olla itself may need to be replaced after a few years, the stoppers can be reused indefinitely.
After researching the work of Potters for Peace and their production of ceramic water filters, I became interested in whether altering the porosity/wall thickness of the ollas would affect their efficiency. In order to test this, I made ollas of a consistent size with 3 levels of porosity.
The first set was only clay (marked “R”), with wall thicknesses of 1/8″, 1/4″, and 1/2″.
The second batch was a 50/50 mixture of coffee grounds (which burnt out in the firing, leaving behind cavities through which water could drain) and clay, with the same wall thicknesses, marked “C”.
Batch 3 was cloth soaked in clay slip, layered to create similar (though less exact) wall thicknesses, with the greatest porosity after the cloth burned out.
These were all installed in an array of small raised beds, with pepper plants planted in proximity all summer long.
It was found that the plants in proximity to the plain clay vessels grew the largest and were most productive. The 1/4″-walled vessel was the only one which achieved the ideal of complete direct contact with the plant’s roots.