Water harvesting enables savvy farmers sell produce at peak prices

By George Munene
By con­struct­ing water reser­voirs farm­ers are able to save on wa­ter­ing costs as well as avoid re­li­ance on rain-fed ag­ri­cul­ture—al­low­ing them to pro­duce over the drier sea­sons when most ag­ri­cul­tural pro­duce is scarce and com­mod­ity prices are at their peak.
Timothy Mburu con­struc­ted his 50 mil­lion liter ca­pa­city dam on half an acre in 2011. It was 2015 be­fore he first sowed on his five-acre farm at Naro Moru, Nyeri County. Hav­ing not to rely on tap water and chan­nel­ing water into his farm through grav­ity, he has cut his pro­duc­tion costs by up to 60 per cent. For his cab­bages for ex­ample, his wa­ter­ing costs per acre is just Sh 3000—con­sti­tut­ing largely of la­bour. This is com­pared to the other farm­ers around him who spend Sh15,000-20000 on ir­rig­a­tion. “I do not cul­tiv­ate crops over the rainy sea­son—I tar­get my cul­tiv­a­tion over the drier June to Septem­ber months— that way my pro­duce hits mar­ket when the sup­ply is lower than de­mand,” says Mburu.
The dam also doubles up as a fish pond, host­ing tilapia and cat­fish which he sells for an extra in­come.
“As a ca­reer ag­ri­cul­tur­al­ist trained in crop pro­duc­tion and water re­source man­age­ment, I had an acute un­der­stand­ing of how im­port­ant it was be­fore any­thing else, being that farm­ing is a wa­ter-in­tens­ive un­der­tak­ing, that I have a re­li­able source of water. My dam en­sures I have clean water for both crop ir­rig­a­tion (cab­bages, pota­toes and gar­lics) as well as wa­ter­ing my an­im­als (15 cows and 20 sheep) throughout the year.” he says.

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For Caleb Karuga hav­ing a water pan on his farm was a no-brainer. In 2010 he had been hav­ing major water prob­lems and farm­ing on leased land, he could not sink a bore­hole or well. On his farm at Kikuyu sub-county, he’s set up a 144,000 liters pond; a do it your­self pro­ject that cost him Sh43,000—Sh20,000 in labor costs and an ad­di­tion Sh23,000 in buy­ing a dam liner. “I would have had to buy 14 plastic tanks with 10,000 liter ca­pa­city at a cost of Sh980,000 to har­vest the same amount of water. I tap water from my goat shed and gut­ters on my chicken coop which is all fed into the reser­voir. The pond has made me an un­wit­ting fish and bee farmer be­sides keep­ing my farm ir­rig­ated for three to four months, “he ex­plains.
It has also cre­ated his own ma­gical oasis, a cyc­lic eco­sys­tem that be­gins with the rain­wa­ter wash off de­pos­ited from the goat’s shed full of ni­tro­gen­ous waste. To this, he adds chicken ma­nure to provide the per­fect fish breed­ing ground. He is also now got into duck rear­ing—they also provide ma­nure, spur­ring phyto­plank­ton growth giv­ing his fish even more food. This ‘im­proved rain­wa­ter’ provides readymade li­quid ma­nure for his ve­get­ables, lu­cerne for his goats, sweet potato vines, straw­ber­ries and maize. He is now even able to ‘zero graze’ his own bees which have a read­ily avail­able water source mean­ing they do not have to wander.
To con­struct his dam Mburu spent Sh1.2 mil­lion—an ex­or­bit­ant amount given that when he built it in 2011 dams were still a novel idea for most farm­ers; re­source mo­bil­iz­a­tion in terms of get­ting a gov­ern­ment-owned ex­cav­ator to his site took him al­most a month and cost him Sh12,000 to run every hour. With an eight hour work­shift the pro­ject was com­pleted in 26 days. “Today you can hire the same ma­chinery at half the cost and with the pro­lif­er­a­tion of private com­pan­ies of­fer­ing ex­cav­ator ser­vices you do not have to spend the Sh100,000 I did just to get the bull­dozer and its per­son­nel to my farm, “he points out.

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On an­other five acres he re­cently ac­quired, he’s worked to con­struct a 110 000 liter water pan on an eighth of an acre. With his worn ex­per­i­ence this has cost him just Sh20,000 in hired labor. He is work­ing on pro­gress­ively in­creas­ing it to sit on half an acre, with a 20-30 mil­lion liter water hold­ing ca­pa­city.
His 50 mil­lion liter dam sits on half an acre but the water con­sumes just ¼ of this with the rests con­sti­tut­ing com­pacted walls. The walls are four meters high above the ground with a slanted depth of three meters—this is done to re­duce the wall pres­sure to pre­vent the dam from burst­ing. At the top of his walls, he grows tough grass such as Kikuyu which spreads by pro­du­cing a thick mat or thatch above the soil sur­face which im­proves com­pat­ib­il­ity pre­vent­ing soil erosion. Trees should not be grown on the dam’s walls as their roots will crack into the dam’s walls to sip water.
A water reser­voir should be set up out of the dir­ect site of run­ning water and the im­pact of on­rush­ing water re­duced by put­ting up de­tours that re­duce the ve­lo­city of on­rush­ing water.
Mburu does not con­trol for evap­or­a­tion; “Not once have I ever run out of water—50 mil­lion liters can ir­rig­ate a 10-acre farm for 90 days— the ger­min­a­tion time for most crops— if some 100,000 liters is lost through evap­or­a­tion, that is neg­li­gible,” he says.
Caleb urges Kenyan farm­ers to con­sider water har­vest­ing as es­sen­tial to crop pro­duc­tion and not just as a way of tap­ping water for human and an­imal con­sump­tion.