Grow your vegetables without soil

Wednesday January 29 2020

An agronomist explains how to plant vegetables in soilless media. Photo by Michael Kakumirizi

Some of the factors limiting crop production are environmental challenges of mushrooming pests and diseases which are soil-borne and as such farmers are encouraged to adopt alternative farm practices.

In this regard hydroponic farming (soilless farming) serves as a promising farm practice that offers a solution for some serious challenges of crop production such as lack of arable land, climate change, deforestation, rising fossil fuel use, ecosystem degradation, rising water and food scarcity.

Hydroponic farming as a soilless farm practice directly eliminates the dependence of crop production on the soil as one of the primary resources. This is the thinking of science experts majoring in sensitising farmers to adopt growing of certain crops using hydroponic technology.

According to a publication in Agrivi website titled, Hydroponic Farming: A Turning Point in Growing Crops, the technology is described as the practice of growing crops by using mineral nutrient solutions instead of soil to deliver water and minerals to the crop roots.

Traditionally the soil supports the crop’s roots by helping them remain upright and ensuring the delivery of water and essential nutrients. In hydroponic farming, crops are supported artificially. Therefore, the nutrients are supplied by using various practices that bring mineral nutrient solutions to the crops.
Seeds of Gold spoke to Papius Tumusingizi of Makerere University Agricultural Research Institute Kabanyolo (MUARIK) about the best practices farming under hydroponics.

Types of hydroponic farming
Tumusingizi explains that there are various types of hydroponic farming. Hydroponic farms can be set outdoors, as well as indoors within greenhouses, or in a completely controlled environment using artificial light. There are the two main types of hydroponic farming systems, passive system uses a growing medium to retain moisture and supply the nutrients and active system brings the water and nutrient solutions by utilising the pipes.
There are many variations and possible settings for hydroponic farms.


Wick system
Wick system, which is the passive system, meaning there are no floating parts and the crops are supported by ordinary trays or other growing mediums where the nutrient solutions are supplied from the reservoir with a wick.

Water culture system
Which is the simplest of all active hydroponic systems, the roots of the crops are completely immersed in the water; the platform that holds the plants floats directly on the nutrient solution; an air pump supplies the oxygen and the nutrient solution to the plant roots. Plants such as onions, spinach and lettuce grow well in this system.

Drip system
This is probably the most used hydroponic system where the nutrient solutions and water are pumped from a reservoir to each plant using a small drip line; the pump is controlled by the timer.

Setting a hydroponic farm
Tumusingizi notes that it is important for the farmer to know which type of crop to grow and which nutrients to provide for the growth of a plant. Plants require nutrients such as sulphur, nitrogen, phosphorous, potassium, magnesium and calcium among others. The combination for every crop differs and so it is important for farmers to know what is required for a particular crop.

The fertiliser made for hydroponic farming is required to be soluble in water. Farmers are advised to purchase what is made specifically for hydroponic farming.
Fertilisers such as Dap are not good but the type of Urea and a particular type of NPK made specifically for hydroponic farming are the best to use.

For outdoor planting it is important for the farmer to clear the land and cover it with polythane paper. Then the farmer is at this point expected to introduce boxes of media.
The media can be sawdust, volcanic soils, gravel and sand where seedlings are planted and fed constantly with liquid concentrate of nutrients to allow the plant to grow well.

Hydroponic crop production can be a challenging practice for some farmers, particularly because it demands knowledge of crop nutrient interaction as well as an understanding of the hydroponic system.
Since it is extremely important for the farmer to immediately respond to any changes in nutrient concentration, hydroponic crop production requires regular monitoring.

Furthermore, hydroponic farming also requires high set-up costs and farmers are prone to facing challenges of power failures and water-borne diseases that are required for green house hydroponic farming.

Why practice hydroponic farming?
Regardless of all of the disadvantages, hydroponic farming is a sustainable farm practice that offers a few remarkable benefits.

Using the technology, farmers are able to grow crops year-round where there are no seasonal limits, crops can develop faster, improved crop nutrition; crops don’t waste energy trying to find the nutrients in the soil, water efficiency, less water usage than soil-based farming; excessive water is collected and pumped right back to the plants, nutrients don’t leach away, there is no competition with weeds, soil-borne diseases are eliminated, the practice is less-labour intensive, it’s possible to grow in a monoculture and a farmer can be focused on market demands instead of crop rotation practices.
Farmers are capable of farming year-round without having to account for soil fertility, drought, weeds, crop rotation and soil preparation practices.

Types of crops
Plants grown hydroponically are of exceedingly high quality, occupy less space, and consume fewer resources than traditional growing methods.
Hydroponic techniques also makes it easy to grow large amounts of vegetables in small spaces or even indoors. This makes it easy to grow year-round food.
While the basic concept of hydroponics is growing plants in nutrient solution with or without the use of a soilless medium, many methods have been developed over the years to suit different purposes and availability of resources.

Farmers can grow mainly fruit vegetables such as tomatoes, green and sweet pepper, cabbages, lettuce, amaranth, flowers and fodder for animals among others. In Uganda it is mainly commercial flower farmers that have taken up use of the technology as well as Dr Emma Naluyima who is growing forage for feeding her pigs but other small scale farmers are opting for the outdoor farming.

Nutrient film
Nutrient film technique system is where the nutrient solution and oxygen are pumped from a reservoir into the growing tray; the plants absorb the nutrients and oxygen from the flowing solution and then drains nutrients back into the reservoir giving the crops a constant flow of nutrients.
Aeroponics system where crop roots hang in the air and the timer controls the nutrient pump which provides nutrients to the crops via mists every few minutes.