Clay Pot Irrigation part 2 of 3

The Chinese first wrote about Clay pot irrigation 2000 years ago.  The book Fan  Sheng-chih shu which described the setup as follows (Bainbridge, 2000)

“Make 530 pits per hectare, each pit 70cm across and 12 cm deep.  To each pit add 18kg of manure.  Mix the manure well with an equal amount of earth.  Bury an earthen jar of 6 L capacity in the center of the pit.  Let its mouth be level with the ground.  Fill the jar with water.  Plant four melon seeds around the jar.  Cover the jar with a tile.  Always fills the jar to the brink if the water level falls.”

Clay pot irrigation has shown a dramatic increase in efficiency over traditional watering methods.  As in drip irrigation, clay pot irrigation decreases the amount of water used and the time required to attend to the crop.  After the initial setup, clay pot irrigation allows the farmer to fill the pots intermittently, between once to twice a week on average.  Water savings may be as great as 90% when compared to conventional surface irrigation.  (Bainbridge, 2000)

It is estimated that 30% of a farmers time is taken up by weed management.  (Grattan, Schwankl, & Lanini, 1988) As shown with drip irrigation, clay pot irrigation has demonstrated a significant reduction in weeding.  The time saved between a reduction in the time of weeding and watering your crop would be beneficial to any farmer.  This is especially critical when “In 2008, 90 percent of all income for farm house-holds came from off-farm activities.”  This is also beneficial to individuals who would like to have a home garden.  (Briggeman)

Mr. Daka (PhD student) demonstrated the efficiency of the clay pot irrigation in terms of water usage.  This individual wrote a PhD titled Development of a Technological Package for Sustainable use of Dambos by Small-Scale Farmers. Chapter 7.2 describes the site selection of his experiment on clay pot irrigation.  The region that used for the experiment experienced 600-800 mm of rainfall/year and was in a semi-arid region of agroecological zone II of the southern province of Zambia.  They chose this region because of the difficulty of transporting water from wet zones and good drainage.  This presented the problems of water transport as well as increased drainage leading to difficulty of maintaining soil moisture.  (Daka, 2001)

This experiment compared water requirement, yield responses, and suitability of clay pot irrigation to small-scale farmers in comparison to watering can irrigation.  The experimenter did not use sprinkler irrigation but does include comparative data of sprinkler data.  The experimenter found in his study that  “statistically significantly higher yields with the clay pot irrigation system than with the watering can system were obtained for three of the seven crops, viz. cauliflower, maize and rape.”  (Daka, 2001) Maize had an increase in yield of 58% while cauliflower and rape had increases of 38% and 26% respectively.  The study also noted “In no case did the clay pot system give significantly lower yields than the watering system or substantially lower yields than the sprinkler system.”  (Daka, 2001) I was unable to find a direct study between clay pot irrigation and drip irrigation.  (See image 1)

It is important to note that water savings between 50% and 70% occurred compared to the conventional watering can system.  (See image 2)  Furthermore clay pot irrigation maintained favorable aeration and soil moisture retention while the above ground watering led to crusting of the soil, causing low soil infiltration of the water and poor aeration.  (Daka, 2001) Similar crusting may occur with sprinklers and typical rainfall.  Decreased water usage in clay pot irrigation may be due to the following; a decrease in the transpiration of water through greatly reduced competitive weeds and a decrease in surface evaporation due to the clay pot being buried beneath the surface.  The researcher found that the roots of the tested plants surrounded the clay pots directly or penetrated deep into the soil within the portion where moisture remained.  (Daka, 2001)  (See image 3)  Water flow through the pot depends on moisture density in the soil and air.  (Vasudevan, Thapliyal, Sen, Dastidar, & Davies, 2011)

The clay pots irrigate the plants due to the porous nature of the clay used.  The plants themselves automatically regulate the water intake thus removing any guesswork from irrigation calculations.  Water is pulled from the leaf of the plant into the stem, the roots, through the soil, and then from the clay pot irrigator because of the cohesive properties of water.  Once placed, the water in the clay pot seeps into the soil until the soil is saturated.  At this time, the water no longer seeps through the pores of the pot.  (Vasudevan, Thapliyal, Sen, Dastidar, & Davies, 2011) 

Once a seed or transplant enters the saturated area, it will begin to imbibe the water from the soil.  As the plant uses that water, the pull of water goes from that plant, through the soil, and to the pot.  When needed the pot seeps more water into the soil to make up for what the plant has transpired.  This process is continuous allowing the plant to use as much or as little water as it desires.  The farmer then needs only fill the pot regularly (recommended when pot is half full).  (Daka, 2001) The time frame generally accepted for filling the pots is around 3 days to a week depending on size, and climate.  Automatic filling of clay pots would be a simple irrigation procedure further decreasing the work required by the farmer.

Image 1

















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Sources on post 1 of 3

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