Farmers from arid and semi arid areas have been urged to turn to imported crystals which help in arresting and retaining water for crop use long after rains and irrigation.
Super Absorbent Polymer (SAP) are just like particles of sugar, but after the rains, they absorb water and they increase in size to that of a ballast particle.
“The SAP is the same that is used as a moisture absorbent in diapers. It collects urine, therefore, preventing leakage,” said Alex Mwangemi, one of the farmers who have been using this crystals in his sunflower farm.
He explains that 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 which can be used by the plant for more than two weeks .
“Water concentration in the clods is 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,” he said.
He revealed that 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 and 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 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.
Just like the crystals in the diapers do not cause harm to the skin of children, SAP does not affect the soil, the roots or any other organisms for the four years it is available in the soil before breaking down.
“We are currently importing the crystals for other farmers and a bag of 25kg is selling at Sh16,000. A farmer requires 80kg to 90kg per acre, although the application rate may be determined by the area climate,” he said.