By Murimi Gitari
Studies show that the global cropland area per capita decreased from about 0.45 hectare per capita in 1961 to 0.21 hectare per capita in 2016. This shows that most of the land that is suitable for crops growing is already in use, calling for the need to come up with alternative farming practices.
Vertical farming, whereby plants, foods and herbal medicines are grown in vertically stacked layers, inclined surfaces or containers using the hydroponics or nutrient film techniques, has proved to be one of the most suitable alternatives. Francis Kabiru, a director at Nairobibased Miramar International College that offers agriculture-related short courses, says hydroponics uses less water and space than conventional farming while producing a bigger and faster harvest in any climate.
The college, which has a demo farm in Muthiga, Off Waiyaki Way, also specialises in the manufacturing, installation and marketing of customised hydroponic fodder and vegetable systems. Mr Kabiru, who is also a biotechnologist, recommends the adoption of the vertical farming technique especially in urban and peri-urban areas where real estate has taken up agricultural land.
With a greenhouse of 8m by 30m, one can multiply the space to get production equivalent to that from almost an acre of land. Since vertical farms spread upwards, farmers are able to grow three to 10 times more crops in the same amount of space as conventional farms, depending on the layout.
Seeds are planted in soil-free growth mediums such as coconut husk to provide the seedlings with a surface to attach their roots.
This soilless process minimises the risk of invasion by bugs and weeds.
Seedlings are placed in growth trays stacked upwards in vertical farming system.
“In hydroponics, we substitute soil with other media such as pumice extracted from volcanic rocks and coco pit or rock wool to anchor crops,” says Mr Kabiru.
He says that vertical farming is considered a highly efficient and sustainable way of producing food.
With automation, everything happening inside the greenhouse like temperature, carbon dioxide, humidity or light is easily managed and controlled.
“Farming in a controlled environment like the greenhouse helps reduce the use of pesticides. This is because crops are not exposed to pests and diseases as compared to open field farming,” Mr Kabiru says.
In Nutrient Film Technique water is fed through pipes which reaches the crops directly. This limits water contamination which can cause water borne diseases like Bacterial wilt in tomatoes.
The water is then recycled to the bleeding tank or resoivor. This minimises the amount of water used in the greenhouse.
“Plants growing in vertical farms are fed essential nutrients hydroponically, in which nutrient-infused water is fed to the plant roots which sit in a growth medium,” says Mr Kabiru.
Hydroponic farming in a controlled environment does not rely on weather. This means that fresh produce can be grown all year round.
Being a controlled environment, crops are able to reach their full genetic potential and a farmer can harvest any crop on a weekly basis and never lose yield to pests and soil contamination threats.
Feeding is done twice a day using an automated pump. This ensures that you spend less time in the greenhouse and minimal labour is required.
One does not need to weed as the environment is controlled with very minimal weeds and pests around or inside the greenhouse.
But a farmer needs to keep monitoring the progress of the crops in terms of growth and development.
One should also get the right measurements for electro conductivity (EC) — the amount of iron that is in the nutrient solution fed to the crops — PH and clean water when preparing the nutrient solution.
“It’s important to get good quality and clean irrigaton water to be used in mixing the nutrient solution for feeding,” says Kabiru.
One of the biggest challenges in hydroponic farming is the setup of the greenhouse as it is a bit expensive.
But Mr Kabiru says one is able to recover the expenses within two cropping seasons.
Keeping crop production in a controlled environment enables trained scientists and advanced climate control technology to optimise the inputs of water, nutrients, and light fed to the plants.
For instance, one can measure the amount and nutrient content of the water that each plant transvaporates.
This gives farmers insight into the amount of unused water and nutrients by the plants at each stage of the growth process. From this, farmers are able to ensure the maximum amount and highest quality of yields by optimising the timing, quality, and amounts of inputs to the plants. The water used in hydroponics is reusable, which cuts the costs to a farmer.