How to grow tomato on soil-less media

Saturday November 16 2019

Mwonda regulates the temperatures in the

Mwonda regulates the temperatures in the greenshouse.  

By Denis Bbosa

Farouk Mwonda energetically walks towards one of his mega-greenhouse structures at Makerere University Agricultural Research Institute Kabanyolo (MUARIK) in Gayaza. It has been a long and busy day for everyone at the institute which is 21 Km north of Kampala on Gayaza-Ziroobwe road.
Hydroponic refers to growing crops without soil. It makes use of water with soluble nutrients necessary for the plant and inert (empty of elements) media (substrate) like sand, rock pebbles, coconut peat, pumice, rock wool, macadamia husks and coffee husks.
Mwonda, the greenhouse manager at Korea International Cooperation Agency (KOICA) says they embraced smart farming at their tomato demonstration farm and are grateful it is yielding. The drip hydroponic system is a must have for any smart agriculture enthusiast.

Soil-less medium
“We do not use soil, but a growth medium that depends on drip to send water to the roots. We buy nutrients such as potassium, nitrogen, phosphorus, zinc and many more for our tomato production,” he reveals.
Mwonda adds that their idea is geared towards ensuring food security in this unpredictable climate and the technology ensures that farmer controls every stage of production.
“Here everything is controlled by the machine, we do not depend on any climate changes. We control the temperature, light, carbondioxide and PH (it has to be 6-7). The nutrients are absorbed as nutrients, and temperature for tomato has to be 20°C and 21 °C, you can’t control this in outside gardens.”
The crop expert says the light initiate the opening of the stomata which is used in the photosynthesis for the plant to manufacture its food.

Mwonda regulates the temperatures in the
Mwonda regulates the temperatures in the greenshouse.

At their Muarik project, they harvest the nemoneta tomatoes twice a week, Monday and Friday up to eight months before replant.
“The major advantage is that it is disease-free, the bacterial wilt in all soils are prevented since we don’t use soil.” The white flies are barred from entering by the use of a net and, therefore there is no need to use herbicides thus the tomatoes grow organically only feeding on nutrients like calcium carbonate. In peak season, they harvest 300 kilogrammes of good quality tomatoes. Normal yield is 200 kilogrammes in two days.
They sell each kilo at Shs2,500 at Nakasero market and at the same price to Gayaza market since they are a demonstration farm. Mwonda asserts that the tomatoes are tasty and juicy.
Drip hydroponic
Also called the Aqua M, the machine regulates nutrients flow up to the green house, the machines work well within a mean environment control.
“We have a mini weather station behind the facility and the machine is set automatically to irrigate when temperature increases.
There are three tanks; buffer tanks, nutrients tank and water reservoir for water to dissolve nutrients.”
“The machine has an EC meter to measure nutrient current sensor tells us the right EC (2-3), has PH sensor for hydrogen concentration in the solution, it keeps PH in check.”
It has a pump that sends nutrients to the sieve tubes, then to the micro meters that supply directly to the roots of the plants, these are the cock-fits growing medium that hold the roots that act as soil.
Water, fertiliser
Tomato production requires that plant nutrition is monitored carefully and regularly. Tomatoes require a well-drained growing medium, regular watering and regular applications of fertiliser.
The application of water is typically done with a trickle irrigation system composed of distribution lines with drip tubes or spray stakes.
Drip tubes or spray stakes are placed at the base of each plant. Tomatoes use a great deal of water, especially in warm weather, so to control the irrigation system it is highly recommended and relatively inexpensive for good yield of tomato.
On feeding regimes of greenhouse tomato, many types of fertiliser have been used.
Generally, the fertiliser is moderate in nitrogen and high in phosphorus, potassium, calcium and magnesium.
A grower must be sure that calcium and magnesium are included in the fertiliser programme for better yield of tomato. Normal plant and fruit growth requires these nutrients to be present in the correct amounts. The fertiliser typically comes in two parts, calcium nitrate and a complete fertiliser (without calcium).
This is because calcium nitrate is not compatible with other fertilisers in the concentrated form.
Many growing media can be used successfully for greenhouse tomatoes. Good field soil in the greenhouse floor or packaged commercial growing media composed primarily of composted bark, peat or coir, perlite alone, peat-lite mixes, rock wool slabs and straw bales.
However, these are not locally available, therefore, greenhouse soil media should be amended with organic fertiliser regularly to retain soil health.
Farm yard manure should be used to keep soil organic matter status high.

Pest and disease control
Insects and diseases can be a big problem because so few pesticides are labelled for greenhouse vegetables, and their use should be the last solution to pest and disease management in tomato.
The best method in disease management is forecasting the disease incidence, especially late blight and early blight.
Their incidence is normally attached to the weather condition in the greenhouse, and destructive humid warm conditions.
This should be avoided by placing good ventilation system to control greenhouse microclimate.

Classroom for farmers
Barbara Balungi, the programme manager of Inclusive Business Solution (IBS) at the Korea International Cooperation Agency (KOICA), says farmers using the technology tend to have higher yields.
This is because one is able to con


trol nutrients in the plant. “It’s good because you are able to know what you need to add and the quantity,” says Balungi.
This model farm is also a classroom for farmers interested in hydroponic farming. “We train new farmers who want to start this

method of farming,” says Balungi, who has opened a training centre sponsored by KOICA at Kabanyolo, where agronomists conducts courses weekly. Juma Kidodo, a farmer in Namulonge, was her student. Kidodo finds the technology beneficial and easy to use. “I’m making good money from the sale of tomatoes I harvest using this method. I am very grateful to KOICA,” he says.

Tomato plants in a greenhouse are pruned to a single stem. All lateral branches or suckers must be removed when they are one to three inches long.
Koica project
Korean government is working with Makerere University Agricultural Institute Kabanyolo (Muarik) and Chonbuk National University through KOICA IBS project. The project which includes hydroponic greenhouse tomato planting will help Ugandan farmers increase production and household incomes. Barbara Balungi the project coordinator says the technologies have already been implemented. “We ahave started training farmers. The greenhouse is already producing ripe tomatoes, we also have a poultry project which is also underway,” says Balungi. Dr Kim Jong Kun the KOICA programme director launched the project on Thursday at Kabanyolo.