Efficient traditional methods of irrigation that could be of great use on small and medium sized farms and gardens were not well studied or publicized until recently. The olla (buried clay pot or pitcher) method of irrigation is one of the most efficient systems known and is ideal for gardeners and small farmers and can be used in a patio container.[1] I first learned about it in a Chinese agricultural text from 2000 years ago. Olla irrigation uses a buried, unglazed clay pot filled with water to provide controlled irrigation to plants as the water seeps out through the clay wall at a rate that is influenced by the plant’s water use.
Why use ollas?
A 2013 study in Kenya found the olla system was much more efficient than furrow irrigation —saving 97.1% of applied water for maize and 97.8% for tomatoes. The increase in yield per unit of water was up 32.2% maize and 43.7% for the tomatoes. In a study in India, the yield of olla irrigated melon was 25 tons/hectare using only 2 centimeters of irrigation water, compared with yields of 33 tons/ha using 26 cm of water with flood irrigation. The stable soil moisture maintained by olla irrigation enables crops to be grown in saline soil or with saline water where conventional irrigation would not work. High tomato yields, 27 tons/ha, were obtained in India using saline irrigation water, EC 10.2 mmhos/cm.
In addition to being more efficient than drip systems, ollas can be used without pressurized, filtered water supplies. The clay pots can be made with locally available materials and skills and are less likely to be damaged by animals or clogged by insects than drip systems. And finally, the ollas may require added water only once every few days or once a week. This makes ollas ideal for farmers and gardeners who are busy with other crops, children, household duties, or who must work away from home much of the week.
Olla irrigation allows soil amendments to be placed only where they will benefit the crops not the weeds. This is very important as studies of traditional farming systems have found that as much as 30% of the labor is for weeding — labor that could be put to more productive use.
A study in India found that the dry weight of weeds was only 62 kg/ha using ollas compared to 465 kg/ha with basin irrigation. In one of my tests there were kilograms of weeds instead of tons per ha.
How to Get Started
- Buy or make a test olla. Make sure water seeps through the pores and wets the outside of the olla
- Dig a pit wider and deeper than the olla (mix in manure and compost if possible)
- Fill the pit with water — let drain
- Put the olla in the hole after adding enough soil in the pit so the stem is about 5 cm above ground.
- Fill the pit around the olla and firm up the soil by pressing on it
- Fill the olla with water and cover the olla opening with a lid or stone
- The next day see how far out from the olla the soil is still damp
- Plant seedlings or place seeds in the damp soil
- Refill olla as needed
- After the season is over scrub the pots and store upside down.
Any good potter should be able to make ollas. If pots are made specifically for irrigation the clay should not be fired much above 1,000°C or the porosity will be limited. Adding more grog (ground old ceramic) to the mix can increase porosity. The drawbacks of ollas include the cost of the ollas and the energy required to make them. The pores in the pots may clog over time and require scrubbing and soaking with some vinegar or re-firing to clean out the pores.
Buried clay pot irrigation is outstanding. Try it this year. It works so well for container plants. Grow parsley, mint, chives, cilantro, egg plants, cherry tomatoes, or flowers for home use. Or try them for a garden or small farm.
Further reading
Kefa C.C., E. C. Kipkorir, J. Kwonyike, P. C. Kubowon, H. K. Ndambiri. 2013. Comparison of water use savings and crop yields for clay pot and furrow irrigation methods in Lake Bogoria, Kenya. Journal of Natural Sciences Research. 3(8):34-39.
Bainbridge, D. A. 2015. Gardening with Less Water. Storey Publishing.
Bainbridge, D. A. 2013. Fan Shengzhi an agronomist of ancient China. https://works.bepress.com/david_a_bainbridge/35/
Bainbridge, D. A. 2001. Buried clay pot irrigation. Agricultural Water Management 48(2):79-88.
Stein, T.-M. 2019. Pitcher irrigation bibliography: https://www.vl-irrigation.org/content/thematic-content/pitcher-irrigation/pitcher-irrigation-bibliography/
[1] YouTube https://www.youtube.com/watch?v=voibQvxkSXs
