Soil-less farming using hydroponics for fresh produce

With the pressure to produce more food with less available inputs such as land or water, an enterprising small business in Marondera is growing vegetables using hydroponics, a revolutionary farming technique that defies conventional norms of vegetable gardening. Hydroponics involves growing plants in a water-based, nutrient-rich solution, eliminating the need for traditional soil.

A trip there to buy some lettuce and peppers from them resulted in this article.

Still quite an unusual sight in Zimbabwe, mainly due to its significant setup costs, a hydroponic setup does, however, have several advantages over traditional vegetable production.

Economic and production advantages

Some of the most pressing challenges facing farmers today are water scarcity, climate unpredictability, rising input costs, market demand for quality produce, and the need for sustainable farming practices that can provide reliable income streams.

Hydroponic systems significantly outperform traditional field agriculture in yield because growth rates are faster and crops can be grown continuously without crop rotations. This means more production from less space and eliminates seasonal limitations, allowing farmers to grow and harvest vegetables throughout the year. This provides consistent income streams and meets market demand regardless of weather conditions.

A hydroponic system requires much less land area compared to traditional farming, making it ideal for farmers with limited acreage or those looking to maximise production per square metre.

The system uses up to 90% less water than traditional irrigation methods through complete water recycling and reticulation systems. In drought-prone regions, this is a game-changer.

Farmers can control almost all growing conditions - temperature, water, nutrition, and spacing - leading to optimal plant health and reduced waste of expensive fertilisers.

This operation runs entirely on solar power with battery backup, eliminating dependence on unreliable grid electricity - a major concern for many farmers in Zimbabwe.

The controlled growing environment results in superior produce with less insect and disease damage, no soil contamination, and consistent appearance. The controlled environment also significantly reduces the need for pesticides, especially soil-borne disease treatments, supporting organic or low-chemical production approaches.

Unlike field crops subject to weather variations, hydroponic systems provide reliable, consistent harvests that buyers can depend on.

Risk management

The greenhouse environment protects crops from weather extremes, droughts, floods, and seasonal variations that increasingly threaten traditional farming. Disease control is also an advantage with the elimination of soil-borne diseases and better control of airborne pathogens through environmental management.

Once established, the automated systems also reduce daily labour requirements compared to traditional farming methods.

In the greenhouse I visited, rows of leafy greens, herbs, peppers and tomatoes were flourishing in the perfectly balanced hydroponic system. Each plant receives precisely measured nutrients, oxygen, and light, ensuring unparalleled growth and flavour.

It is also an extremely effective setup as a space saver compared to most forms of agriculture, without the need for crop rotations as well as the ability to change the spacings of plants at different stages of plant growth.

The setup

This hydroponic setup has two systems in the greenhouse. The first is Nutrient Film Technology (NFT), where all the leafy green types of plants such as lettuces, spinaches, and herbs are grown. The second system is the Dutch/Bato Buckets system, where the vine and fruiting types of crops such as tomatoes, cucumbers and peppers are grown.

The NFT system is best suited for leafy green crops that are fast-growing whilst the Dutch Buckets are best suited for vine crops, including peppers. Peppers are a difficult crop to establish in hydroponics, but if done right, could grow and produce for up to three years.

Nutrients are controlled by a "Dosa-tron" unit that is plumbed into the various blocks and systems throughout the greenhouse. The Dosa-trons test the water continuously whilst they pump through testing for EC (electroconductivity) as well as pH levels. When levels drop below the set parameters on the Dosa-tron, it automatically injects nutrient concentrates until the hydroponic water levels increase to the correct EC levels. "Thus far we have been lucky enough with our water source being an alkali source and when adding the nutrients/fertilisers this acidifies the water and brings down the pH to within the recommended growing requirements," the farmer explains.

This system has incorporated as much basic technology as possible to allow them to take out the possibilities of human error and in future, with the hope of adding more automation controls in future.

Power

When it comes to sustainability, this operation excels in terms of power saving. With the challenge of power outages that we all face living here, this business uses solar power for all utilities throughout the greenhouse. The hydroponic farming method does not require much energy depending on the type of setup and depending on if there is active or passive ventilation. In this instance, the greenhouse is fully supplied by a 15 kva solar system that powers all fans, pumps and batteries, enough to run 24 hours a day without the need for electricity. When there are extended days of cloud cover, there is a generator for backup to charge up the batteries and run the utilities. Currently, the system only has partial temperature control through evaporation pads and large extraction fans, this only cools down the greenhouse, and not heats it and there is no form of lighting within the system for now.

Both growing systems have complete water reticulation systems, which means all water and nutrients used are continuously reused and recycled. As its name clearly states, hydroponics is based on water as its medium and the quality of that resource is ensured by yearly testing. Furthermore, the water supply is trusted, coming from a well on the property.

Disease and pest control

When dealing with disease control, the farmer explains that it should generally be less of a concern, particularly soil-borne diseases, but there are airborne diseases that can become an issue if temperatures and humidity are not controlled. Keeping a controlled and hygienic environment should reduce these forms of diseases.

Although trying to maintain an organic approach to pest management, there have been hurdles with some of the crops having sensitivities to the organic sprays and other crops have started succumbing to pest pressures that the organic sprays do not keep at bay. "Thus, we have had to bring in more conventional insect controls to get on top of these pressures but now we are back on track with an amended program to get back on to a mostly organic basis."

Skills and training

When asked what kind of training or skills are needed to manage a hydroponic farm successfully, the answer is to do your homework. Research and skills learning are a big part of running a successful hydroponic farm. As many parameters need to be followed and understood just one parameter out can ruin a crop unlike in general field agriculture it can be a lot more forgiving. Hydroponics is expensive to set up but once running, has a very low cost of operation.

Currently, the produce is marketed through community WhatsApp groups and by word of mouth.