Hydroponic has proven to be the most water-efficient and space-efficient cultivation method for leaf vegetables. According to studies, hydroponic growing saves as much as 94% of water usage compared to conventional field farming.
The most obvious difference between field farming and hydroponic farming is that hydroponic farming requires no soil. We understand that majority of pests come from the soil. Without soil, crops and plants require no or extremely minimal pesticide during their growing cycle.
Hydroponic crops are generally free from pesticide residues thus safe and healthy.
Another great benefit of hydroponic farming is that nutrients and the environment are highly controllable. Different nutrients formula and lighting could change the shape and taste of the crop easily.
To understand all the benefits of hydroponic farming, please read Benefits of Hydroponic Farming
Types of Hydroponics
There are various types of hydroponic growing methods. The investment budgets, labor costs, production scale, land size, crops and plants to grow, water resources, weather, and climate, are the common factors influencing the selection of hydroponic methods for commercial farming. For details on how to choose a suitable hydroponic type, please read this post “which hydroponic method should you choose?”
1. Deep Water Culture (DWC) System/Kratky
Water culture refers to a growing system with a floating foam board floating on a reservoir of water. The root of the plants is immersed in water to absorb the required nutrients. Such a system can be as large as over 100m3, or as small as a used jam jar (Kratky, please read “What is a Kratky Method Hydroponics?“).
Water culture is suitable for leafy vegetables such as lettuce, spinach, water spinach, Pak Choi, kale, etc. However, draught crops, root vegetables, climbing crops, or larger plants are not a good choice.
2. Nutrient Film Technique (NFT) System
The Nutrient Film Technique is one of the popular hydroponic methods for commercial farming.
NFT system is built with PVC NFT channels for nutrient solution to pass through. There are holes punched on the top side of the channel at a set distance to house hydroponic baskets.
All sorts of hydroponic mediums can be used in the NTF system. The core concept is to allow a thin film of nutrient flow through the channels where roots absorb nutrients via the nutrient flow stream.
The nutrient flows back to the holding tank and circulates again and again.
Aeroponics is a modern type of vertical farming hydroponic derived from NFT. By arranging grow holes vertically, the root systems of the crops are hanging in the air. With the nutrient stream raining down and passing through the root system of crops, nutrient circulation is similar to the NFT system. Aeroponics well uses space, is easy to organize, and links multiple units to form a larger system.
The significant benefits of NFT are:
- easy to operate and build automation to control nutrient solutions
- flexible and scaleable, can be built to multi-level systems to save space and boost high yield per square
- less water and fertilizer used compared to DWC (Deep Water Culture)
- suitable for a wide variety of leafy vegetables
- the best option for both home and commercial growers
3. Drip System
The hydroponic drip system uses various growing mediums such as coco coir/peat, and rock wool blocks with drip needles inserted into the growing medium to provide continuous nutrients to plants. Similar to NFT, but instead of pumping a thin nutrient stream, the nutrient solution is delivered to each plant via drip hoses and needles.
Drip needles are inserted into the growing medium of every individual plant. Nutrients are delivered to every single plant slowly. The excessive nutrient solution will be collected and flow back to a storage tank for circulation.
The drip system is suitable for rich root system crops, larger and climbing plants, such as tomato and cucumber, etc.
The most common form of a hydroponic drip system is to use rock wool slabs. Seeds will be germinated and propagated in rock wool cubes, then transplanted onto rock wool slabs.
4. EBB and Flow
Ebb and flow is a form of hydroponics for its simplicity, reliability of operation, and low initial investment cost. Pots are filled with a growing medium that anchors the roots and soaks up nutrient solution from the bed/table, functioning as a temporary reserve of water and nutrients for the root system. The hydroponic solution alternately floods the system and is allowed to ebb away.
Pots of plants are placed in a water-tight growing bed/table. The growing medium may be composed of material that enables the root system to reach the level ebb reaches such as rock wool, and coconut peat, clay balls. A mixture of these different types of medium can absorb the moisture, and allow root system ventilation, more evenly and efficiently than using a single type of medium.
The bed/table is periodically flooded for a short period (5 to 10 minutes) with a nutrient solution pumped from a reservoir. By placing the nutrient solution reservoir below the growing bed, the nutrient solution can drain back by gravity.
This hydroponic growing system can be very effective for any size plant depending on space. The method is inefficient in its use of water and plant nutrient reagents. Root disease and nutrient element insufficiency can occur without proper aeration.
Since it is a rather closed circulation system, monitoring of pH, EC, and PPM of re-circulated nutrient solution flowing back into the reservoir is vital. This can either be done manually or via automated control & dosing system.
5. Dutch Bucket
The theory of dutch bucket growing is quite similar to EBB and Flow in some aspects, eg. plants grow in a selected growing medium which helps to support the root system, as well as to reserve moisture and nutrients for plants. The excessive nutrient solution will flow back to a storage tank for re-circulation.
Dutch bucket is suitable for rich root systems, large plants, and climbing crops.
The volume of the dutch buck has plenty of room for the very rich root system to develop. It helps support the plant too.
The most common growing medium for the dutch bucket system is clay balls. Clay balls absorb and hold nutrient solutions for the plant. Spaces in between allowing plenty of air for the root system to “breath”. Furthermore, there is no excessive water immersing the root system, great for plants requiring well-drained growing conditions.
Aquaponics refers to a farming method that incorporates aqua animal culture alongside plants/crops (such as vegetables) and water culture. It consists of two main parts, the aquaculture part for raising aquatic animals (usually fish) and the hydroponics part for growing plants.
Aquatic effluents, resulting from uneaten feed or raising animals like fish, accumulate in water due to the closed-system circulation of most aquaculture systems. The effluent-rich water becomes toxic to aquatic animals in high concentrations but contains nutrients essential for plant growth.
These two main parts of aquaponics systems require several subsystems to effectively remove solid wastes, for adding bases to neutralize acidity in water, or for maintaining water oxygen content.
Typical subsystems found in an aquaponic system:
Fish holding tank: the tanks for raising and feeding the fish;
Settling tank: a unit for catching uneaten food and detached biofilms, and for settling out fine particulates;
Bio-filter: a place where the nitrification bacteria can grow and convert ammonia into nitrates, which are usable by the plants;
Hydroponics system: the portion of the system where plants are grown by absorbing excess nutrients from the water;
Sump: the lowest point in the system where the water flows to and from which it is pumped back to the fish tanks.
Depending on the sophistication and cost of the aquaponics system, the units for solids removal, bio-filtration, and/or the hydroponics subsystem may be combined into one unit or subsystem which prevents the water from flowing directly from the aquaculture section of the system to the hydroponics section.