A low-cost and innovative way that traps water and nutrients and concentrates them in an area that resembles a half moon is gaining popularity among farmers in the semi-arid Isiolo area who have embraced the technique to diversify into water-guzzling horticulture farming.
The Merti area of Isiolo receives pockets of rainfall. But when it rains, it pours. The challenge, however, is how to capture water and hold it where plants can use it directly. Various water harvesting techniques have failed as the scorching sun dries the water before the farmers can even start land preparation.
But a visit by one of their own to West Africa has changed their water harvesting venture through the use of semi-lunes. This is a French name meaning half moon and denoting the shape of the contours. They are in the shape of a semi-circle with the tips of the bunds on the contour. They come in a variety of sizes, which help with water harvesting in semi-arid areas.
Contours are marked out on the bare ground and an A-frame is swung around to trace a semi-circle. The crust of the earth is broken with pickaxes and the soil is dug out by spade. Small earthen bunds the size and shape of ordinary dikes are built up along the curve of the semi-circle. The demi-lunes are lined with manure and compost, and seeds are placed in and around them.
Two years into the practice, yields have increased and farmers who traditionally grew drought-resistant crops like finger millet, and sorghum are comfortably growing water-guzzling crops including tomatoes, capsicum, and onions.
“I was very particular about this kind of farming when one of the locals introduced me to it. At that time, even the little rain we used to get once in a while was becoming elusive. I had nothing to lose, I decided to try it,” said Ajara Abdi one of the farmers who now supply fresh produce to hotels and supermarkets in Isiolo town.
Due to the scarcity of rain, Ajara started by sourcing water and putting it into the contours, and with the manure he got from his livestock, it took him just a few days before he set up the demi lunes. He has ten such dunes which have assisted him in harvesting 20 kilos of tomatoes, 15 kilos of capsicum, and 50 kilos of kales. “This has been an oasis in the desert, and it cost me nothing. At least with the lunes I know I can farm for eternity. The trick is to wait for the little rain to come and harvest as much water in the dune as possible,” he added.
Osman Abdi an agricultural officer who visited Niger and learned of the transformative farming technique was the first to trial it in his farm. “I was tired of lack of pasture for my livestock. The trip which was on an exchange programme to Niger was a game changer. At a time when livestock in the area is dying due to unpredictable weather which has taken a toll on fodder, I am guaranteed of year-round supply of animal fodder,” said Osman. His lunges are specifically used to grow animal fodder. He is one of the largest suppliers of meat and camel milk to Nairobi’s Eastleigh area.
When it rains, the bunds help retain run-off water in the demi-lunes. The stored water also percolates over the area, acting as subsurface irrigation.
The lunes have also been hailed for healing the infertile soils of the region which have been destroyed by excessive human behaviour including farming and overgrazing.