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When used in gardening, can be DIY'd with terracotta plant pots buried in the soil, with the drainage hole filled and top covered.

Olla irrigation works like this:

• When the soil around the olla is dry, the soil pulls the water through the wall of the olla and into the soil, (the tension is between wet and dry), thus providing water for the roots.
• When the soil is wet from rain or has not dried out yet, there is no tension and the water is not pulled through the wall of the olla.