What is Hydroponics?
Basically, hydroponics is simply the production of crops in a soilless medium. In hydroponic farming nutrients dissolved in water are either delivered directly to plants roots or through an inert medium such as rock wool.
The history of hydroponic farming can be traced back to 1627 with Francis Bacon’s work on water culture but not until around 1929 when a University of California at Berkeley scientist, William Frederick Gericke began to publicly promote the use of solution culture in agricultural production. The earliest large-scale success of hydroponic farming was in the 1930s on Wake Island, a rocky island in the Pacific Ocean used as a refueling station for Pan American Airlines. Hydroponic farming techniques were used extensively in the soilless island to grow vegetables for airline passengers.
In conventional farming, plants grow their roots deep into the soil to find the necessary nutrients needed to grow. In hydroponic farming, the liquid nutrients are delivered directly to the roots hence saving the plant’s energy and time required to grow the roots. This energy is redirected to foliage, fruit, and vegetable production.
In hydroponic farming, the farmer has total control over the plants. They are in control of availing water, oxygen, and nutrients hence ensuring that the plants get the required nutrients and at the correct amounts. Not only does this speed up growth and maturity, but the farmer’s schedule is more stable and hence able to plan accordingly.
Hydroponics solves most of the current problems, soil quality, and water availability, facing the agricultural sector. Hydroponics has been used to grow foods where they previously couldn’t grow.
In hydroponic farming, there are generally two techniques used; plants roots are suspended directly in the nutritious solution hence availing the roots with abundant nutrients and oxygen. In the second technique, the plants’ roots are anchored on an inert medium such as rock wool which has an open structure hence providing a highly oxygenated root zone.
Types of hydroponic farming systems
Hydroponic farming systems incorporate different soilless farming techniques to maximize production while saving on costs. There are six different hydroponic farming systems.
This is the most commonly used hydroponic system because of its simple and easily modifiable operation. The main operating principles are simple making easy to use. Vital plant nutrients are dissolved in a water tank which becomes the nutrient reservoir which is kept away from plants. The nutrient solution is then pumped through a network of drip irrigation pipes to individual plants.
The pump can be controlled by a timer – bypassing manual irrigation-hence making it possible to have a regular and timed irrigation of the plants. When an emitter is attached at the end of each irrigation pipe, you can control the timing and amount of nutrients to each plant. This means you can plant a range of crops on the same system.
There are two subtypes in the drip hydroponic systems:
- The recovery drip hydroponic system
- In recovery drip systems, there’s a provision for recycling excess nutrients. The excess nutrient solution drains back into the nutrient reservoir making the system for efficient. Recovery drip system requires regular inspection as concentrations of nutrients diminish over time as they are taken up by crops.
- Non-recovery drip hydroponic system.
- Non-recovery drip system does not recycle excess nutrient solution. This type requires less maintenance as ph and nutrient levels remain constant. Non-recovery drip system also minimizes disease spread throughout different plants.
Ebb and flow hydroponic system is also a popular hydroponic system due to its relative simplicity in setting up and operating. Just like the drip hydroponic system, flood and drain system uses a reservoir tank full of nutrient solution. The nutrient solution is pumped and flooded on the growing tray. After flooding, the pumped goes off and the solution in the growing tray trickles back into the nutrient reservoir.
A timer in the pump is set to activate the pump, periodically flooding the crops on the growing tray. The timer can be set to come on at different times depending on the type and size of plants, temperature and humidity and the type of growing medium used. Some growing medium such as gravel and perlite don’t hold water for long hence may need more frequent flooding than in other water holding media such as rock wool, vermiculite, and coconut fiber.
Since the runoff filters back into the reservoir, the hydroponic system is very low in maintenance and self-sufficient. On the downside, the nutrient solution in the reservoir tank needs a frequent inspection for optimal nutrient, oxygen, and ph levels.
This is the most basic type of hydroponic growing and is widely used in classroom instructional settings. This system uses a reservoir to hold the nutrient solution which is wicked up to the growing medium by capillary action. In this system, it’s important to use a good wicking (water sucking and holding) growing media such as vermiculite, rock wool, perlite, or coco coir.
In the wick system, the most critical component is the wick. For an efficient system, you need a good absorbent wick for optimal delivery of nutrients to the plants. The common materials used in the wick systems include propylene felt strips, fibrous rope, tiki torch wicks, rayon rope, wool felt, polyurethane yarn, nylon rope, cotton rope, or strips of fabric from old blankets.
The major downside with this system is that it doesn’t work for larger plants that require larger amounts of the nutrient solution since the wick can’t keep up with the delivery. The other con with the system is that it requires frequent flushing since excess nutrients might build up to toxic levels around the roots.
This is the oldest type of hydroponics and has been widely used for instructional purposes because of its technical simplicity. In hydroponic water culture systems, plants are suspended directly into the reservoir tank containing the nutrient solution. While the plants’ leaves are suspended above the floating Styrofoam, the roots are submerged into the nutrient solution.
Since the nutrient solution is stagnant in the reservoir, a pump is required to pump oxygen into the solution hence maintaining optimal oxygen levels.
There are four techniques used for aeration in this system:
- Air bubbles: An aquarium air pump and air stones are used to introduce air bubbles into the nutrient solution. The airstones are made of porous rock like material with the small pores creating many individual air bubbles which rise to the top of the nutrient solution near the roots.
- Falling water: In this version, falling water splashes hence incorporating oxygen. The higher the fall or the larger the volume of water, the bigger the splash which means more oxygen is incorporated and provided to the growing crops. This method of aeration is commonly used in commercial water culture where large amounts of water are used.
- Circulating water culture system: This is a variation of water culture system works on the same principle as flood and drain system only that the nutrient solution is never drained. Circulating water culture system allows utilization of falling water as an aeration source.
- Deep water culture (DWC): This is a variation of water culture system with the only difference being the depth of the nutrient solution. In true DWC, the nutrient solution depth is 8 to 10 inches deep. The depth of the solution is mostly determined by the size of the plant’s roots, nutrient and water requirement, or the type of container used.
Although water culture system is quite technically simple, it can be limited in the range of crops that can grow in this system. Since the roots are submerged in the nutrient solution, some plants die off due to excess nutrients and only water-loving plants such as lettuce do well in this system.
Although this system is popular with many hydroponic growers, it is only suited for growing quick-growing plants such as different types of green vegetables such as lettuce, baby greens, and other types of herbs.
In NFT system, the nutrient solution is continuously pumped into the growing table or pipe which gently slopes to allow a gentle flow of the thin nutrient film which collects and drains back into the reservoir. The plant’s roots are suspended in the space in the growing table or pipe. The flowing nutrient solution passes beneath the roots dampening and giving them an opportunity to absorb dissolved nutrients and water.
This system allows a continuous supply of nutrient solution to the growing plants hence eliminates the need for a timer and thus needs less attention in controlling the system.
In NFT system, the flow rate of the nutrient solution and the slope gradient of the growing table or growing tubes are major factors on nutrient delivery and overall efficiency of the system. The recommended slope of the growing table is 1:30 to 1:40 ratio, that means 1 inch in vertical drop for every 30 to 40 inches horizontal length. It’s recommended that in designing the system, the slope should be adjustable while plants are growing so as to keep up with the growing roots and avoid stagnation.
The recommended flow rate in NFT system is typically 1-2 liters per minute for each growing tube. The flow rate should be adjustable as younger delicate plants require lower flow rate compared to bigger maturing crops. Flow rates (higher or lower) are usually associated with nutrient deficiencies.
Nutrient film technique is highly associated with power outages hence regular pump and electric maintenance is essential to avoid system failures where the roots may dry out rapidly.
Although it is the most technical hydroponic system, aeroponic systems have been slated as the solution to future food shortages as it utilizes the least amount of water.
In this system, just like the NFT system, the plants’ roots are suspended in the air with their roots hanging in the air. The nutrient solution is pumped from the nutrient solution reservoir to high-pressure pump which is then sprayed as mist over the hanging roots. This system ensures maximum oxygen availability to the roots. Because the misting provides less amount of nutrients than in other systems hence the spraying takes place more frequently.
Due to the frequent circulation and spraying, the nutrient solution in this system is the most oxygenated resulting to faster growth and maturity rates of crops in the hydroponic aeroponic farming system.
This technology is looking promising for future food production because the system offers the possibility of growing crops vertically thereby maximizing production on a small area.
The major factor affecting aeroponic growing system is the size of the droplets. Roots sprayed with fine small droplets grow much faster and with larger surface area for absorption of nutrients than roots sprayed with large water droplets like in sprinkler heads.
There are three subtypes of aeroponic growing system categorized according to the water droplet size.
- Low-pressure aeroponic system (soakaponics): Although they aren’t the most efficient of aeroponics systems- because of large droplets-they are the most popular aeroponic systems because of their low cost and don’t require much in terms of special equipment. This system is usually uneconomical in large-scale growing.
- High-pressure aeroponic systems (true aeroponics): Although high-pressure systems are expensive and technically complicated, they are the most efficient aeroponic systems. In these systems, the nutrient solution is highly pressurized (60-90 psi) to atomize the solution into a fine mist with very small droplet size. In high-pressure systems, the roots get maximum oxygen and nutrients resulting in faster crop growth and maturity.
- Ultrasonic foggers: Ultrasonic foggers are used to generate mist. These foggers are usually used in creating visual displays on ponds or stage. Although they are capable of producing mist, there is very little actual moisture in the fog. The other downside with ultrasonic foggers is that the fog seems to drop to the bottom making it difficult to ensure the roots are covered by the mist at all times.
Types of hydroponic growing substrate/ inert media
Having known the different types of hydroponic techniques, the next obvious decision before setting up a hydroponic system is which growing medium to use. Hydroponic medium is inert and can’t grow anything on its own and its major function is providing support and anchorage for the plants.
There are different media and their applicability differs from one growing technique to another.
- Expanded clay aggregate: These are baked clay pellets which are inert and a neutral ph. The clay pellets are fired in 1,200 oC which causes expansion making them porous hence suitable in hydroponic systems.
- Rockwool: Is composed of granite and limestone which is melted and spun into small thread-like cotton candy. It can be formed into cubes, slabs, sheets, or flocking. Rockwool is an inert, porous non-degradable medium that easily absorbs water. The ph should be balanced, by soaking in ph balanced water, before us.
- Coco-fiber/chips: Although the coconut fibers are organic, they are one of the best-growing media since thy breakdown and decompose without providing any nutrients to the plants growing. Apart from being inert, coco coir has a neutral ph and holds moisture well at the same time allowing proper aeration for the roots. The difference between coco coir(fiber) and coco chips is the size of the article where coco fibers have small sized particles compared to coco chips. The larger the particle size, the better the root aeration.
- Perlite: This is a volcanic mineral rock that has been superheated to expand it and hence becoming more porous, lightweight and absorbent. Perlite has a neutral ph and an excellent wicking action. It can be used alone or mixed with other substances such as granite. Perlite is lightweight and it tends to float around hence not a good choice in flood and drain systems.
- Vermiculite: Is a silicate mineral which is expanded by superheating it. Vermiculite’s properties as a growing medium are similar with perlite with the only difference being that vermiculite has a high cation-exchange capacity hence it can hold nutrients for later use.
- Grow stone: Are made from recycled glass. Grow stones are unevenly shaped, porous and have a good wicking ability of even up to 4 inches above the water level.
- River rock: It’s common and easy to find in many home improvement stores. River rock is inexpensive and comes in irregular rounded shapes hence making them suitable in aeration and drainage in the roots. Since the rocks are nonporous, they are unable to hold on to moisture around the roots hence they are applicable when mixed with other media to improve drainage.
- Floral foam: It’s a lightweight and porous material. Depending on the hydroponic growing technique used, the floral foam may get water logged very quickly and it can also crumble easily causing a mess.
- Sheep wool: This is a promising renewable growing media. In comparison to other media such as coco coir slabs and rock wool, sheep wool had a greater aeration/ air capacity of 70%which decreases to 43% with use and water capacity increased from 23 to 44% with use. The study showed that sheep wool yielded the most compared with other substrates.
Other popular growing media include rice husks, sand, gravel, and water absorbing polymers among others. In case of you plan to use naturally occurring substrates, it is recommended you sterilize the media before use to avoid contamination
Which nutrients are added into the solution?
The grower provides all necessary nutrients required which could have been otherwise got from the soil. The greatest advantage of hydroponic farming is the ability of the farmer to control and provide tailor made nutrients to the plants.
The type of nutrients added depends on the type and requirements of a particular crop. The grower is also at liberty to choose if they want to pursue organic farming by adding organic nutrients or otherwise.
Hydroponic nutrient mixtures are usually available in many stores and most of them come with the basic mineral nutrients required for a plant to grow. The major minerals needed for plant growth include Nitrogen, Copper, Sulphur, Molybdenum, Boron, Chlorine, Potassium, Zinc, Magnesium, Calcium, Iron, Manganese, and Phosphorus. Others like Carbon, Oxygen, and Hydrogen are absorbed from the atmosphere.
The temperature of the nutrient solution is also critical. Warm temperatures of about 68-72 degrees provide optical growth.
Advantages of hydroponic farming.
- Steady production: The greatest advantage of hydroponic farming over traditional methods is that it gives the farmer total control over crop production hence stable production. Elimination of weather influence ensures productivity all year round.
- Use less water: Although hydroponics use water as a solvent, its uses the least amounts of water since most of it is recycled thereby reducing water expenses for the farmer.
- Early maturity: Due to the controlled and tuned-up growing environment, plants grow and mature faster than in traditional farming. This means earlier harvest which translates to more profits for selling on the off-season and more planting seasons in a year.
- Free of soil-borne diseases: In hydroponics, it’s easy to detect and control crop diseases before spread. Soilless technology also ensures there’s no possibility of contracting the many soil-borne diseases.
- Use less space: Since hydroponic farming systems encourage intensive farming, less space is used to produce more food.
- Use fewer nutrients: Since the delivery of nutrients is controlled and directed directly to the target roots, efficient use of nutrients is maintained unlike in the traditional farming systems where most nutrients are lost in the soil or taken up by the weeds.
- Saves on labor costs: Most of the hydroponic systems use a timer for nutrient irrigation thus eliminating the need for manual irrigation. In hydroponics, there are usually no crop maintenance works such as mulching, tilling, or weeding.
Disadvantages of hydroponic farming technology
- Water-based organisms could spread through across the grow area causing crop damage.
- The initial set up is expensive and some technical expertise is also required in growing the crops on hydroponics.
- Hydroponic systems are vulnerable to power outages as pumps rely on power to run. Power outages may lead to drying out of plants due to lack of moisture.
Setting up a hydroponic system
In adapting to this new way of farming, you need to consider tools and supplies that are a must have when operating your hydroponic system. The most common and crucial supplies and tools in hydroponic farming systems include:
- Air and environmental supplies: These include filters, bug screens, duct tape, and thermostat. They are important in controlling the environmental conditions around the plants.
- Accessories: They are the basic components of the system which include timers, water and air pumps, meters, tubing systems, clamps, trays, reservoirs, and fittings.
- Lighting equipment: These include fluorescent bulbs that are important for indoor growing.
- Pest control supplies: These include insecticides and sulfur evaporators Wilmond Sulfur Burners that are instrumental for keeping harmful insects away from plants.
- Reinforcing tools: These supplies are used in reinforcing your system for stability. They may include ballast, hangers, cords, filters, and sockets.
Before setting up a hydroponic garden, there are two main considerations:
- Grow area: You’ll need to clear up a small area which can fit the basic components of the system and the grow table. The area should have optimal lighting away from any shade.
- Type of hydroponic system: Apart from the varying setup costs, each system requires a different level of expertise and technical know-how.
Regardless of the system, all hydroponics has need few basic components:
Hydroponics Growing tray
This is basically the container holding the plants. The area provides plant support and access to the nutrient solution. The growing area also protects the roots from pests, excess heat, and light which can damage the roots. Size and shape of the growing tray depend on the type of hydroponic system and the type of plants you intend to grow. Many containers can be used but care should be taken when dealing with metal containers because of their corrosive tendencies.
This is the container holding the nutrient solution. It is from here that the solution is pumped either periodically or continuously, depending on the system, to the grow tray. Reservoir tank can be made from any container provided it doesn’t leak, holds enough solution and is clean. The size of the reservoir container depends on the size of growing area.
Hydroponics Submersible pump
The pump located in the reservoir pumps the nutrient solution up to the growing chamber. Choice of pump capacity depends on the size of growing area to be fed and height from the pump to the growing tray.
Hydroponics Delivery system
These are mostly PVC pipes used to deliver the solution from the pump to the growing chamber and from the chamber back to the reservoir. Depending on the type of system, the delivery system might be composed of individual drip pipes or sprinklers.
This is a basic clock timer which is connected to the submersible pump. The timer switches on the pump at regular intervals depending on how it’s set. Timed nutrient irrigation ensures that crops are well nourished at all times.
Hydroponics Air pump
Air pumps are used to pump oxygen into the nutrient solution. This ensures that roots receive sufficient oxygen for optimal growth.
Plants require enough lighting for growth. Depending on the location of your setup, it’s important to ensure the crops get sufficient light.
This is a complete guide to Hydroponics Farming that I use and will cover everything not covered in this blog.