News and knowhow for farmers

Coast farmers cut irrigation costs with water storing crystals


More than 1,000 Coast region farmers are turning to imported crystals  that help in ‘arresting’ and retaining water for crop use long after rains and irrigation.

Alex Mwangemi, who is part of the about 1,500 Magarini Jatropha Farmers Association, has been using super absorbent polymer (SAP) for more than one year in his sunflower farming.  

“I call this SAP dry water. The crystals, are just like particles of sugar, but after the rains, they absorb water. Each of them increases in size to that of a ballast particle. That is more than 50 times expansion,” Mwangemi said.

The SAP is the same that is used as a moisture absorbent in diapers. It collects urine, therefore, preventing leakage.

In the soils, the polymer collects any water particles after rains or irrigation and forms heavy wet lumps of soil, from which crop roots draw water by a physiological process, active transport.

Water concentration in the clods in higher than that in the roots. But the mineral concentration is higher in the roots than the surrounding. Water is, therefore absorbed into the roots.

The water is available for use for about two weeks. 

READ ALSO: Why you need drip irrigation for higher profits

The crystals are most appropriate in greenhouses, where they can reduce the cost of irrigation by more than 80 per cent per week because the holes are almost fixed all year round.

Instead of watering crops twice a day, the excess water from one time irrigation is stored for later use.

“SAP is added into the soil during planting. Between 0.03g and 0.05g (approximately one glass soda bottle-top) of the crystals are added to the hole of a seeds, grains or seedlings. Starting with the available water around the crop during planting, it will be collected and stored in the reservoir gel-like crystals for use when it gets dry,” he said.

One bottle top can hold two to four litres of water.

The collection model is the same for open fields. Instead of irrigating daily, one can adjust to once a week, therefore, saving on costs of production.

READ ALSO: Trench water harvesting sustains farm two months after long rains

Just like the crystals in the diapers do not cause harm to the skin of children, SAP does not affect he soil, the roots or any other organisms for the four years it is available in the soil before breaking down.

The group is importing the SAP for sale to farmers.

A bag of 25kg is sold at Sh16,000.  A farmer requires 80kg to 90kg per acre, although the application rate may be determined by the area climate.

Mwangemi, who was showing other farmers the ‘dry water’ irrigation technology at the Mombasa International Agricultural Society of Kenya Show, hails from Kilifi County’s Marikebuni Village. 

Mwangemi can be reached on +254724706579.

PHOTO: Alex Mwangemi displays gel-like crystals after they have absorbed water, which he added in less than 20 minutes. The super absorbent polymer crystals keep water for about two weeks for use by crops. They can reduce cost of irrigation for farmers. PHOTO BY LABAN ROBERT.

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