December 3, 2009
Dr. Tsegay Wolde-Georgis, Consortium for Capacity Building, University of Colorado
There is a consensus that global climate change will lead to unprecedented impacts around the world. Many specifically fear that the long-term achievements of the UN Millennium Development Goals (MDGs) will be jeopardized by climate change without multifaceted intervention. A major impact of climate change is adverse yet-to-be determined changes in precipitation around the world. The normal (expected) seasonal rainfall and temperature in a specific location is expected to change radically in amount, distribution and timing. Changes in the onset, continuity and end of seasonal rainfall are expected to disrupt food production and other climate sensitive socio-economic activities, especially in developing countries.
The hundreds of millions of subsistence farmers around the world who are the backbones of the food supply are in danger of losing their livelihoods due to climate change and variability. The rainfall dependent subsistence production sector is already vulnerable to natural seasonal variability due to the lack of farm infrastructure and low inputs. It is high time to take adaptive measures to cope with the impacts of climate change on the amount and distribution of rainfall as well as changes in temperature.
Recently, there has been growing interest on the use of simple traditional techniques to cope with impacts caused by climate and water hazards. The World Bank recently organized the 2009 Development Market Place (DM2009) in November 10-13 that brought 100 global competing finalists to deal with climate change. The organizers funded 26 of the finalists with up to $200,000 for 2 years. My proposal on the use of unglazed use clay pots for small and local level micro irrigation in the arid zone was one of the 100 finalists. Even though the proposal was not among the 26 funded projects, this ancient — but not widespread — innovation has led several participating organizations to seek collaboration to implement the idea in their home communities in Africa and in Southeast Asia
Below are some details on the use of this traditional technique of subsurface watering system as an example of the role that simple technologies can play in changing the lives of poor farmers.
The use of buried clay pots for irrigation is an ancient technology that was used in China, the Middle East and North Africa. An ancient Chinese agricultural text written 2000 years ago was quoted by David Bainbridge:
“Make 530 pits per hectare, each pit 70 cm across and 12 cm deep. To each pit add 18 kg of manure. Mix the manure well with an equal amount of earth. Bury an earthen jar of 61 capacities 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 fill the jar to the brink if the water level falls.”
As stated in this ancient Chinese guide book, unglazed clay pots are buried in the sub-soil and filled with water. The seeds or seedlings are planted around the water-filled buried clay pot. The roots of the plant take advantage of the sub-surface water that seeps through the pores in the pot to wet the soil and water the plants. The amount of water taken by the plant depends on its need. The process is also called auto-irrigation, since the plants seek water from the wet front around the water filled pot. During hot days, for example, the plants lose moisture due to evapo-transpiration and therefore draw more water from the pot.
The clay pot irrigation system extremely saves water as the following chart developed from Elias Daka’s data illustrates. As the chart shows, onion and tomato save 70% water using clay pots compared to the conventional can watering used for that experiment. Even though there is high demand for labor initially due to the purchasing, burning and burying of the clay pots, once the system is set, the frequency of filling the pots with water is between one to two weeks -depending on the size of the pot and the water demand of plants and the environment. Sub-surface irrigation also denies indiscriminate moisture to weeds. Unlike surface irrigation, the use of clay pots does not lead to salinity and saline water can be used to water plants. The problem of malaria epidemics related to irrigation is also absent, while using clay pot irrigation systems.
The widespread adoption of clay pots for irrigation at household and community levels can help farmers to grow vegetables, herbs, spices and fruit trees around their homesteads and provide their food needs. This will supplement the declining food supply, using the seasonal rainfall that often grows grains. Bainbridge estimates that a well planted 400 square meter of land under clay pot irrigation can support an average family of four’s annual food needs.
This shows that response to climate change and variability need not be the use of sophisticated and expensive technologies. Simple technologies such as water harvesting and irrigation using clay pots, which is available in every rural household, can be useful and increase the resilience of small farmers to climate related hazards.
The clay pot system is more efficient and reliable than drip irrigation. In terms of cost and management the clay pot irrigation system is cheaper and easier to install and manage by the small farmer than other irrigation systems. While drip irrigation is used for the ultra-modern farms that use high technology and highly skilled agricultural engineers, the clay pot system can be operated by ordinary farmers. Clay pots have been a household utensil for thousands of years.
Clay pot sub-surface irrigation system is not widely used, despite its potential to increase food to subsistence farmers. In fact many communities in sub-Saharan Africa are involved in the construction of micro-dams and water harvesting ponds, but they do not know how to use it unless it is suitable for gravity irrigation. The adoption of clay pots irrigation will make the water harvested in these micro-dams more useful and productive. Sometimes a resolution to a problem is close at hand, but it is not being adapted. The new use of the clay pots for micro-irrigation will revitalize the clay pot artisan women and increase their income.
Governments and development agencies should incorporate this and other effective traditional technologies as part of their rural development strategies and in response to climate change. The adoption of such technologies that are easy to comprehend by traditional farmers and made locally will increase their resilient adaptation to the impacts of climate change.