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tapuwa Mashangwa Agriculture Column
As new technologies emerge, the holistic concept of agricultural functionality evolves thus improving production and yields.

Each milestone reached presents new opportunities and better ways to conserve the environment and to still attain agricultural produce that utilises water and other natural resources efficiently, something Hydroponic farming achieves.

Deep water culture is the hydroponic method of plant production by means of suspending the plant roots in a solution of nutrient-rich, oxygenated water.

Traditional methods favour the use of plastic buckets and large containers with the plant contained in a net pot suspended from the centre of the lid and the roots suspended in the nutrient solution. The solution is oxygen saturated by an air pump combined with porous stones.

With this method, the plants grow much faster because of the high amount of oxygen that the roots receive.

Top-fed deep water culture is a technique involving delivering highly oxygenated nutrient solution direct to the root zone of plants.

While deep water culture involves the plant roots hanging down into a reservoir of nutrient solution, in top-fed deep water culture the solution is pumped from the reservoir up to the roots (top feeding).

The water is released over the plant’s roots and then runs back into the reservoir below in a constantly recirculating system.

As with deep water culture, there is an airstone in the reservoir that pumps air into the water via a hose from outside the reservoir.

The airstone helps add oxygen to the water. Both the airstone and the water pump run 24 hours a day.

The biggest advantage of top-fed deep water culture over standard deep water culture is increased growth during the first few weeks.

With deep water culture, there is a time when the roots have not reached the water yet.

With top-fed deep water culture, the roots get easy access to water from the beginning and will grow to the reservoir below much more quickly than with a deep water culture system.

Once the roots have reached the reservoir below, there is not a huge advantage with top-fed deep water culture over standard deep water culture.

However, due to the quicker growth in the beginning, grow time can be reduced by a few weeks.

Fogponics is an advanced form of aeroponics which uses water in a vaporised form to transfer nutrients and oxygen to enclosed suspended plant roots.

Using the same general idea behind aeroponics except fogponics uses a 5-10 micron mist within the rooting chamber and as use for a foliar feeding mechanism. A rotary hydroponic garden is a style of commercial hydroponics created within a circular frame which rotates continuously during the entire growth cycle of whatever plant is being grown.

While system specifics vary, systems typically rotate once per hour, giving a plant 24 full turns within the circle each 24-hour period.

Within the centre of each rotary hydroponic garden is a high intensity grow light, designed to simulate sunlight, often with the assistance of a mechanised timer.

Each day, as the plants rotate, they are periodically watered with a hydroponic growth solution to provide all nutrients necessary for robust growth.

Due to the plants continuous fight against gravity, plants typically mature much more quickly than when grown in soil or other traditional hydroponic growing systems.

Due to the small foot print a rotary hydroponic system has, it allows for more plant material to be grown per square foot of floor space than other traditional hydroponic systems. One of the most obvious decisions hydroponic farmers have to make is which medium they should use.

Different media are appropriate for different growing techniques.

Those commonly used are expanded clay pebbles, baked clay pellets, are suitable for hydroponic systems in which all nutrients are carefully controlled in water solution.

The clay pellets are inert, pH neutral and do not contain any nutrient value; Growstones, made from glass waste, have both more air and water retention space than perlite and peat; Coir, Coco peat, also known as coir or coco, is the leftover material after the fibres have been removed from the outermost shell (bolster) of the coconut.

Coir is a 100 percent natural grow and flowering medium; Rice husks, parboiled rice husks (PBH) are an agricultural by product that would otherwise have little use; Perlite is a volcanic rock that has been superheated into very lightweight expanded glass pebbles.

It is used loose or in plastic sleeves immersed in the water. It is also used in potting soil mixes to decrease soil density; vermiculite is a mineral that has been superheated until it has expanded into light pebbles; Pumice, a lightweight, mined volcanic rock; sand; gravel; wood fibre; rock wool; sheep wool; brick shards and polystyrene packing peanuts, these are inexpensive, readily available, and have excellent drainage.

The writer is Eng Tapuwa Justice Mashangwa, a young entrepreneur based in Bulawayo, Founder and CEO of Emerald Agribusiness Consultancy. He can be contacted on +263 739 096 418 and email: [email protected]