A new agricultural revolution is taking place in Kenya. In urban and peri – urban centres, the country’s latest breed of farmers are creating little farms where none existed: In buckets and plastic containers, sacks and pots. And, curiously, on water as Well – no soil needed.
The technology is spreading fast especially in Nairobi and central Kenya.
In places like Mukuru kwaNjenga, an informal settlement in Nairobi, the slum dwellers have also embarked on farming – putting soil and manure in buckets, sacks and any available containers to grow crops.
All these myriad efforts area bout fighting hunger and ensuring greater food security, concerns that are paramount among farmers. This is especially important because of climate change, which has made seasonal rains unpredictable. When the rains do come, they are often excessive, leading to a cycle of drought followed by ﬂoods.
The farmers are practicing what is known as hydroponic farming – a method of agriculture in which plants are grown in water enriched with nutrients, without using any soil. So far, hundreds of farmers have embraced and adopted the technology. Livestock keepers are using it to grow fodder for poultry, pigs and cattle. Some have adopted it for growing vegetables like tomatoes, kales and broccoli.
The hydroponic technology uses water enriched with a mineral nutrient solution. This solution contains easily absorbable minerals at the right quantities for the growth of fodder, tomatoes, straw berries, ﬂowers and various vegetables. Eliminating soil helps avoid soil-borne diseases, which are notorious for destroying crops.It also helps avoid wastage of water. A lot of water is lost in conventional farming because the soil absorbs some and the rest percolates down to the water table; the plant only absorbs a small fraction of the available water.
Growing crops without using soil also helps a plant to grow faster and retain most nutrients. When crops are grown in soil, most nutrients are lost in the soil or washed away during heavy rains. But the hydroponic process helps to reduce the amount of fertiliser used. Moreover, the plant easily draws absorbable nutrients from the water, growing very fast as a result. Several things are needed in order to start a hydroponic system: A shed, aluminium or plastic trays and containers, clean uncontaminated water, mineral solutions and seeds.
The shed is made of a green material that is easily available in localshops. The material is unique andhelps to maintain temperatures at 17-25°C, the range recommendedfor hydroponic crops. The shed alsohelps to reduce excessive evaporation. A farmer will also need toinvest in aluminium or plastic traysfor growing fodder and plasticcontainers for growing crops suchas tomatoes, onions and strawberries. The trays must be treated toeliminate moulds. The number oftrays that the farmer needs dependson the number of animals that oneintends to feed.
Contaminated water can serveboth as a source and medium fortransmission of diseases. Only asmall amount of water is needed,partly because run-off water is easily recycled.
Perhaps the greatest advantagewith the hydroponic system is thefast growth and early maturity ofcrops. Fodder that would take several months to reach maturity in aconventional field takes only a fewdays to mature in a hydroponic system. The growth and maturity rates of the tomatoes grown hydroponically is similarly high comparedwith those grown conventionally.
The crops are also able to reachtheir full genetic potential. All thenutrients in the plant are retained,and so the fodder is highly nutritious. Farmers say cows fed on thefodder have a higher milk yieldthan those fed on dry fodder andother feeds.
The system comes with a fewchallenges, though. Due to therecycling of the water nutrientsolution, the risk of spreading diseases is very high, and one slightmistake can lead to huge losses.
Though soil-borne diseases areeliminated, the risk of waterbornediseases is high. The initial cost ofputting up the structure can also bea hindrance to many farmers. Theideal size depends on the numberof animals or amount of crops oneWants to plant. The system alsorequires a lot of tender care andclose supervision.
Hydroponic farming was developed hundreds of years ago and isstill practiced in countries such asAustralia. In Africa, it is not widelyused. It now remains to be seenwhether hydroponics will supplantthe soil-filled buckets and sacks inthe slums as well. Cabbages, kalesand onions are all grown usingsuch methods in the slums. Evencrops requiring much water such asarrow roots are grown. For these, ashallow trench is dug and a nylonpaper spread out and then coveredwith soil. The crop is then plantedand irrigated. Water is retainedfor a long time because the nylonpaper prevents percolation into thesoil below it. It is such intelligentmethods of growing crops that haveenabled many families in slums toput food on the table.