Clay Pot Irrigation
Written about in Chinese texts 2000 years ago, utilized by the Romans, and now employed across Latin America, Africa, and Asia, clay pitcher irrigation is a low-tech solution that is helping thousands of communities in arid regions of the world cultivate farmland during dry seasons of the year. These buried, unglazed pots allow water to seep through the clay’s micropores and into the surrounding soil at a rate that is limited by the soil and the plant’s water uptake. This subsurface irrigation eliminates water losses to surface evaporation and infiltration through the soil, improving water savings by up to 70% over conventional surface irrigation methods. Furthermore, productivity is often increased since the plant’s energies are diverted from developing root mass needed for acquiring water, to increasing overall plant yield. Further benefits include decreased soil crusting and erosion, reduction in weeds, and improved efficiency in chemical fertilizers and insecticides applied through the pot. Clay pitcher irrigation is also beneficial in regions where soil salinity is a problem.
Overview
Clay pitcher irrigation is a simple, low-cost solution for dryland farming. Unglazed clay pots with a capacity of seven to ten liters, a conical body and narrow neck, are buried approximately one meter apart with the mouth of the pot exposed. Crops are planted around each pot which are filled with water every four to seven days. Water loss from the pot is regulated by soil moisture content. As water is used by the plant, hydrostatic pressure in the soil decreases and water is transmitted out of the pot. When the surrounding soil reaches field capacity, water loss from the pot decreases. This natural, self-regulating mechanism is what makes clay pitcher irrigation extremely efficient.
Pot Construction
Most third world cultures possess the knowledge for making and firing unglazed pots. Purchasing through local vendors not only provides a
sustainable source of inexpensive pots, but also provides an outlet for income generation, benefiting the local economy. If suitable pots are not available, they can be easily made by hand or on a pottery wheel. Depending on the clay, sand, rice hulls, or sawdust may be added at a ratio of up to 1:4 to increase the porosity of the pots. Although closed-oven firing at temperatures exceeding 450 degrees Celsius is ideal, pots can be fired in open pits at temperatures of 200 to 300 degrees Celsius.
Cultivation
Pitcher irrigation as been used successfully for plants, shrubs, and trees in small gardens as well as larger-scale farming with 3,000 to 5,000 pots per hectare. Many factors affect the efficiency of clay pitcher irrigation; the shape, porosity, and volume of the pot along with soil composition and the number of plants surrounding the pot. Ideally, the soil around each pot should contain a 20% to 50% mixture of compost and/or manure to improve soil composition and porosity. Sand may also be added to soils with a high clay content to further improve the soil. The distance between each pot is generally one to two meters between centers, depending on the crop.
Click Here to see clay pot irrigation in use in Veil Thom, Cambodia where we are demonstrating the technology to local farmers.
For resources on clay pot irrigation visit the following sites:
The University of Pretoria has this is an excellent technical document on clay pot irrigation.
The Organization of American States also has an exellent article.
Pakissan.com has a nice overview article with a nice diagram as does ICARDA.
We have only just started to teach the briquette press in Veil Thom, Cambodia. The community seems interested in the technology, though generally, they seem quite happy with deforesting their land to produce charcoal. It’s my hope that they will find the briquette press a better alternative (cheaper, less labor, higher profit margin etc) and that it will be used widely in the community. Another impetus for it’s success is that I can then us Veil Thom as a model community for introducing the technology to other communities as well as NGO’s.
I am interested in learning how the pots were made, their size, and composition. I am researching this method to use in the southwest US. I’m located in Albuquerque, NM and have been researching this for over a year now. Could you share any findings of the use of the pots?
thanks for any feedback
No problem – The pots pictured are locally made clay pots. The are close to idea actually, and if you are in a situation where you are implementing this as a rural technology, making use of an existing local industry is always best. Key characteristics of the pot are:
Size: between 7 and 15 liters (too small and you water too often, too big and your labor goes way up with digging large holes
Shape: round or squat is ideal
Opening: narrow neck (reduce opening size to reduce evaporation and contamination)
Composition: unglazed porous clay – you can either use a crude clay which has larger/mixed particulate sizes a is not quite pure which will result in larger pores during the firing process. Or you can mix 20% sand with 20% quality clays (the best option) or the same % of sifted rice hulls or or sawdust. The firing process will of course burn out the filler leaving uniform pores and a high-quality pot.
The pots I use are low-quality clay w/ a low firing temperature so they are prone to breakage and/or having pores that transmit water very rapidly. However, in my case it is still judicious to use the local pots rather than trying to create a local industry for manufacturing higher quality pots which would be too expensive for rural farmers to purchase.
As best as I can tell they use course red clay with sand impurities and some straw mixed in (probably less than 20%) and are fired are probably 800 F which is what you normally achieve in open firing pits.
I started a raised bed garden using pots for irrigation.
I am not using any but natural organic matter (no comercial food for plants) my plants are growing aparently healty, but to slow compare to a drip irrigation and comercial food for plants (my neighbor’s garden)
I have never use this sistem before, I asume I am doing well, but I have questions on the water: my wife claims the garden nees more water, but when I planted, I placed the new plants roots, aside to the clay, so my idea is that I probably place the plant to close to the pots and I am geting to much water in the root system.
Can you bring more light about this? please. We are wrowing tomatos, eggplant, corn, green beans, squash, and a few erbs (taht are doing fantastic)
We will apresiate your replay.
I am very much interested in pitcher irrigation,it is a wonderfull method,i want to know the ratio of sand and clay for an excellent porousity of clay pots.