By Saleem Shaikh and Sughra Tunio, Technology times Pakistan
Farmers in the arid district of Sanghar in Pakistan’s southern Sindh province grow vegetables in the sandy ground outside their thatched homes as little short of a miracle.
First introduced to the area in 2008, pitcher irrigation – in which buried clay pots release water into the soil – has expanded to 14 villages. It has provided a fresh source of income for more than 200 families who previously thought it impossible to farm vegetables on these dry lands.
“It is amazing to cultivate vegetables with less water and labour,” says Soomar, who has installed 20 pitchers on the land outside his hut in Rano Junejo village, near Chotiari fresh water reservoir.
Farmers have been unable to take advantage of the reservoir as there is no canal network to distribute water for irrigation. And even if there were, it would likely prove ineffective, as the water would simply be soaked up by the sand before reaching its destination.
“All we did was plant pitchers (in the soil) and sow different vegetable seeds, and it feels as if the vegetables are growing on their own,” adds the exultant 34-year-old.
Ibrahim Mangrio of Padhrio village grows a range of vegetables, including cucumbers, okra and eggplant. Some go to feed his family and the rest are sold at the local market in Sanghar, a bustling town some 260 km northeast of Karachi.
The 45-year-old main source of income is cattle farming, but diversifying into vegetables has generated extra money and better economic conditions for his household.
Around 400 families in Padhrio and other villages scattered nearby rear livestock for a living. But their pastures turn into dry lands and rain-filled ponds evaporate during the scorching summer days from May to July, causing livestock deaths and hiking poverty in the area.
Drinking water also becomes scarce, leading to a rise in water-borne infections and skin diseases.
The poor sanitation and the lack of clean drinking water, coupled with depleting underground water reserves due to insufficient rain, have made life miserable for local people, particularly women and children.
The desert district, bordering India to the east, receives sparse and erratic rainfall, averaging only around 125 mm per year. Heat waves have become longer in the last several years, with the temperature hovering above 49 degrees centigrade from May to July.
In this harsh climate, which could become even more extreme as the planet warms, villagers have had no access to canal water, ruling out crop cultivation in the past. But pitcher irrigation has made agriculture possible, ushering in a new era for local farmers.
Cheap and effective
Also known as sub-surface micro irrigation, it is an efficient method, delivering water directly to plant roots rather than spreading it more widely across fields. The ancient technique has been used in arid and semi-arid regions of China, India, Iran, Mexico and Brazil to grow a wide range of plants.
An unglazed, porous clay pot with a wooden or clay lid is sunk into the ground next to a seedling. Water poured into the pot seeps out slowly, providing the roots with a steady supply of moisture.
The water oozes out of the pot due to the difference in moisture content between its surface and the surrounding soil, until the two reach equilibrium.
The number of pitchers required per hectare differs with the type of crop. Creeping vegetables like cucumber, okra, eggplant and bitter gourd need 2,000 to 2,500 pitchers per hectare, whereas upright and canopy crops, such as beans, tomatoes, leeks and melons, need up to 4,000 to 5,000 pots per hectare.
Saleh Mangrio, Executive Director of the Pakistan-based Centre for Rural Change, has conducted successful experiments with pitcher irrigation at community level in Sindh’s eastern desert under a project funded by the Dutch government and managed by the World Wide Fund for Nature-Pakistan.
The rate of water seepage from a pitcher depends on the type of plant and soil, and climatic conditions, he explains. Once the surrounding soil becomes saturated, water will soak back into the pot, filling it again. “The system is self-regulating and water losses are negligible,” he says.
This method of irrigation is ideal for sandy to loamy soil with good porosity. For small farmers, the system costs around Rs 4,500 (nearly $48) per acre – about 80 percent cheaper than drip and sprinkler irrigation. The yield per acre is around 60 percent higher than with furrow and flood irrigation, which many farmers continue to use, Mangrio says.
The pots are readily available in Pakistan, where they have more traditionally been used to keep drinking water cool in hot months.
Pakistan faces a major challenge in adapting to its fast-depleting water resources. They are coming under increased pressure due to uncertain rainfall, a rising population, outdated and inefficient irrigation techniques and reliance on water-intensive crop varieties.
The country is now classed as a water-stressed country, with less than 1,000 cubic metres per capita water availability, down from 5,500 cubic metres per capita in the 1950s.
But achieving this goal will be difficult unless farmers switch to new methods such as pitcher and drip irrigation, said Altaf Ali Sial, chairman of the Land and Water Management Department at the University of Agriculture in Sindh’s Tando Jam town.
Pakistan’s population is growing at an annual rate of around 2.6 percent, and water use and demand by all economic sectors is increasing.
The Indus River, which provides 80 percent of water for agriculture, is fed mainly by the glacier systems of the Hindu Kush and Himalayan mountain ranges. But global warming is shrinking their snow cover rapidly, which could affect the river’s base-flow.
According to studies by the International Centre for Integrated Mountain Development (ICIMOD) in Kathmandu, run-off into the Indus is predicted to decrease by 27 percent by the year 2050.
Better use of water by farmers could go some way to offsetting that decline in water availability, although low levels of funding for innovative irrigation techniques may well hold back their adoption.
Pitcher irrigation is also being introduced in the western part of southern Baluchistan province, not only to grow vegetables but shrubs to stabilise sand dunes in coastal areas.
“Efficient irrigation water management and its careful use, by promoting water-saving irrigation techniques – such as pitcher, drip and sprinkler irrigations – will help sustain food-production systems in our water-stressed country,” says Pervaiz Amir, an irrigation expert and member of the Prime Minister’s Task Force on Climate Change.
Source: Technology times
Published on: 08/24/2012