By Elisabeth Lawton, Bio E Student
Olla (OY-yah) irrigation provides an elegantly simple, efficient, out-of-site irrigation method best suited for smaller growing areas.
The olla is a round clay chamber with a long neck at the top. The olla is fired but unglazed, ensuring that it remains porous. Typical ollas can hold between one quart and two gallons of water, but can be made to any size. The olla is then buried in the ground so that the opening at the top of the neck is a few inches above the surface. Once the olla is filled with water, the water will slowly seep through the clay body of the olla and into the soil around it. Occasionally cleaning out clogged pores with vinegar will keep the olla functional for many years. The initial cost of an olla ranges from $15 to $30, which can be pricey on a large scale, but their long term benefits and efficiency account for the cost.
Ollas have been used for thousands of years by both the Roman and ancient Chinese empires. Today, olla irrigation is still in use in the Middle East, as well as Central and South America. It is an ideal watering method for dry climates. Watering using ollas is a 70% efficient system, and ten times as efficient as surface watering. Daily watering becomes unnecessary, as most ollas need to be refilled only a few times a week.
After being buried in the earth, ollas can be covered with creative lids to prevent debris or animals from getting inside. Plants will soon grow.
Olla irrigation ensures that the ground will not be soaked with water, but instead only sufficiently moistened. The dryness of the soil and the surrounding plant roots will pull water through the olla walls, but as soon as the surrounding soil is damp enough, water will stop seeping out; this is known as soil moisture tension. Plants can be up to one foot away from the olla and receive water. Because the olla moistens the soil from beneath the surface, soil compaction is reduced. Surface watering causes a lot of soil compaction. Using ollas also greatly diminishes weeds in the garden, which grow on the surface of the soil.
Ollas don’t require frequent care or confusing technology. They are efficient and healthy for the soil and plants. Ollas are an ideal irrigation method for anything from potted plants to raised beds to personal vegetable gardens.