Take advantage of the rains and harvest free water

Friday May 22 2020
farm03pix

Farmers observe a rainwater pond lined with tarpaulin. It is for irrigation. A farmer irrigates vegetables with rainwater harvested in a tank. Photo by Michael J. Ssali

Farming is impossible without water. Animals and plants need water to grow and its availability is the most limiting factor in choosing where to carry out any farming activity.

Water sources
If an area is close to a permanent source of water such as a river or a swamp it is often considered suitable for agriculture since livestock will have ready access to water all the time and irrigation of crops will be possible during times of rainfall shortage.
Another key consideration is the amount, intensity, and distribution of rainfall. Rain fed farming is the mainstay of food and cash crop production in Uganda.

If an area has a lot of rain during only a few months of the year and is very dry in other months it might not be suitable for agriculture unless the farmer has the capacity to store rainwater for use in dry periods.

Storage
Every farmer operating far from a permanent source of water should find a way of harvesting and storing rainwater for use during times of shortage. We are currently getting a lot of rain and most rivers are swollen.

The water that is filling the rivers and causing floods actually begins as rain falling over our homesteads and gets lost through surface runoff and goes into the valley often carrying with it some of the soil from our gardens in a process known as soil erosion.

A farmer can trap some of that water and store it for use during times of rain scarcity. It is also advisable for the farmer to turn to practices that limit surface runoff and facilitate water infiltration into the soil.
One way to do this is to dig gullies across the sloppy garden to trap some of the running water and facilitate its infiltration into the soil.

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Farmer’s viewpoint
Farmers such as John Lubega Wavamunno, of Nkalwe Village, Kingo, Sub-county, Lwengo District harvest rain water from the house roof for backyard fish farming. He has dug a fish pond about three feet deep and twelve by 10 feet in which he rears some four hundred cat fish.

The water cannot seep out of the pond into the soil because the pond is lined with a rubber sheet that he bought at just Shs20,000.
Whenever it rains fresh water is directed into the pond from the roof top.

An equal amount of water goes out of the pond through the overflow pipe into gullies that split it and carry it to various parts of a vegetable garden close to the pond.
He says the water bearing fish excreta is responsible for the vigorous growth and green colour of the vegetables.

He has a metallic tank in which he stores more rainwater from the roof top to pour into the fish pond during the few months of the dry season.

All fish ponds must have fresh water flowing into them and they must have an outlet for the exhausted water.
He harvests the fish after 10 months when they are mature. In order to maintain the same number in the small pond the fish are all female.

“I began rearing fish in a small tank of about 120 litres,” he told Seeds of Gold. “I looked after nine cat fish to maturity in just eight months, and we ate them in my home.”

Collecting vessels
Valuable amounts of water can be collected from the house roof in such containers as barrels, plastic drums, and tanks as large as 100 cubic metres or more.
Some people dig holes and line them with tarpaulin. Rain water does not always have to be harvested from the roof top. Runoff water on the ground can also be trapped and saved in a tank especially if it is for irrigation purposes.

Other farmers have water tanks made with concrete. Such water reservoirs are useful in times of rain scarcity especially for people engaged in poultry, piggery, and other forms of livestock keeping.
Tanks can be constructed underground and the water drawn in a pail fixed on a pole or a rope.

It can also be drawn with hydroelectric pumps. These days there are solar powered water pumps and sprinklers on the market.
Peter Ddaaki of Kitenga Village in Mukungwe Sub-county, Masaka District, has a water tank of 30,000 litres collected from his house roof top. He is a vegetable farmer and he also keeps three Frisian cows under zero-grazing.

“I have not had any water shortage for the last 10 years,” he told Seeds of Gold.
“I use an electric massive pump fixed to hoses some 40 metres long and very good sprinklers. This makes it possible to for us to irrigate the entire farm of some three acres of vegetable and fodder grass. We also use the water for our household needs such as washing clothes and cooking.”

His tank was constructed by digging a hole which was lined with a dam liner sheet to prevent any water seepage. He said it is expected to last 50 years. Before he got the electric massive pump he and his wife would use a pedal pump which was manual and not so effective.
He has smaller tanks in his farm into which the water is pumped before it flows by gravity into tubes fixed with sprinklers.

“Our capacity to carry out irrigation makes it possible for us to produce vegetables for sale all year round,” he said. “We grow such crops as beans and maize when other farmers are waiting for the rains to begin and we have the crops when most of the other farmers don’t.”
Rainwater however is not always absolutely clean because birds often make landing on housetops and drop excreta there.

Dust also collects on the roofs. It is advisable therefore to seek some guidance from a water expert about keeping harvested rainwater safe.
Sanitation is important in the lives of farmers living in rural areas and with sufficient amounts of stored rainwater many farmers are setting up water closet toilets.

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