Urban farming

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. 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 are about 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 fertilizer 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 local shops. The material is unique and helps to maintain temperatures at 17-25°C, the range recommended for hydroponic crops.

The shed also helps to reduce excessive evaporation. A farmer will also need to invest in aluminium or plastic trays for growing fodder and plastic containers for growing crops such as tomatoes, onions and strawberries.

The trays must be treated to eliminate moulds. The number of trays that the farmer needs depends on the number of animals that one intends to feed. Contaminated water can serve both as a source and medium for transmission of diseases. Only a small amount of water is needed,partly because run-off water is easily recycled.

Perhaps the greatest advantage with the hydroponic system is the fast growth and early maturity of crops. Fodder that would take several months to reach maturity in a conventional field takes only a few days to mature in a hydroponic system.

The growth and maturity rates of the tomatoes grown hydroponically is similarly high compared with those grown conventionally. The crops are also able to reach their full genetic potential. All the nutrients in the plant are retained,and so the fodder is highly nutritious.

Farmers say cows fed on the fodder have a higher milk yield than those fed on dry fodder and other feeds. The system comes with a few challenges, though. Due to the recycling of the water nutrient solution, the risk of spreading diseases is very high, and one slight mistake can lead to huge losses.

Though soil-borne diseases are eliminated, the risk of waterborne diseases is high. The initial cost of putting up the structure can also be a hindrance to many farmers. The ideal size depends on the number of animals or amount of crops one Wants to plant.

The system also requires a lot of tender care and close supervision. Hydroponic farming was developed hundreds of years ago and is still practiced in countries such as Australia. In Africa, it is not widely used. It now remains to be seen whether hydroponics will supplant the soil-filled buckets and sacks in the slums as well. Cabbages, kales and onions are all grown using such methods in the slums.

Even crops requiring much water such as arrow roots are grown. For these, a shallow trench is dug and a nylon paper spread out and then covered with soil. The crop is then planted and irrigated.

Water is retained for a long time because the nylon paper prevents percolation into the soil below it. It is such intelligent methods of growing crops that have enabled many families in slums to put food on the table.

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