Agropreneurs are halving irrigation and getting better results during dry spells, thanks to a new product that is creating water storage sacks at the roots of crops.

The water polymer, known as Belsap, comes as granules that are added to the soil at planting time, but which expand by up to 400 times their original size during rains, storing water that they then release, together with nutrients, during dry spells.

The granules are thoroughly mixed with the soil, but only a pinch needs to be applied. Once exposed to moisture, the granules transform into gel or crystals, as they take in the surrounding water.

The performance of these expanded water-containing gels among farmers who cultivate crops as diverse as wheat, sorghum and horticultural crops has been uniform and impressive, with crops gaining the strength to produce more tillers - shoots that grow from the bottom of the original stalk. Quality Farm Produce, which occupies some 80 hectares, 10 km from Nyeri town has began using the granules for growing horticulture produce. With Nyeri set some 1800m above sea level, its conditions can be similar to semi-arid regions, said the farm’s manager, David Wainaina.

“This means that water is a big issue here, especially considering that the tender stem broccoli and the runner beans we plant use a lot of water,” he said.

The tender stem broccoli alone consumes up to 40 cubic metres of water per hectare per day. But Wainaina reports that the farm now only needs to irrigate the crop three days a week, as opposed to irrigating daily as it did previously.

Moreover, the farm has found that the roots of a week-old broccoli plant grown using Belsap are five centimetres long, which is three centimetres longer than plants grown without the polymer at the same stage of germination. The water polymer has also helped in preventing leaching, where fertilisers are washed away from the soil around plants. Belsap does not substitute for the use of fertiliser, said Mr Wainaina, but can be applied simultaneously with the seed and fertiliser.

Jean Njiru, the national sales manager of Bell Industries Limited, the company importing the polymer into Kenya from the US, said that approximately eight kgs of Belsap is needed per hectare of land - depending on the type of crop and soil. Once in the soil, Belsap repeatedly absorbs moisture and stores it. Since roots respond to the moisture, they will grow toward and around the gel. The compound can stay in the soil for seven years if not disturbed.

Although the water polymer has been in Kenya for only three years, it has been in use in the developed world for 40 years, where it is used in many ways in addition to its use in agriculture. It is often added to the soil of potted plants, under lawns and in areas growing grass for as livestock fodder. -African Laughter