All You Need to Know About Hydroponics

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All You Need to Know About Hydroponics

Hydroponics is a soilless plant growing method, using mineral nutrient solutions in a water solvent. The plant roots may be in contact with the solution only with their roots or they may be supported by a medium. 

The main advantages of this type of agriculture, compared to the traditional methods in soil, are faster growth, more yield, no soil processing, controlled nutrients doses and easier health control. 

Hydroponics advantages: 
•    good quality product containing less metal 
•    fewer pathogens 
•    reduce environment pollution, especially groundwater 
•    automatization and minimal labor 
•    possible crop production in conditions where it usually wouldn't be possible - e.g. no soil (Antarctic) or bad quality soil 
•    high yield (normally 2 to 3 times more, but even 4) 
•    needs less water and nutrients 
•    roots have better and constant access to oxygen 
•    the plant takes the exact amount of water it needs


Hydroponics was used in ancient Egypt, even before probably. egypt.jpg

The earliest published work on soilless plant growing was by Francis Bacon, the 1627 book Sylva Sylvarum. Afterwards water culture becomes a popular research field. 

It is important to mention that plants thrive better in less-pure water than distilled water. 

Hydroponics reservoirs are typically built of plastic, but may be made of glass, concrete, metal, vegetable solids and wood. To prevent algae growth, the reservoirs could block the light to the nutrient solution. 

There are several types of hydroponics. Some of them use a medium, some don't. If the medium is used, it should be porous so that the roots have access to oxygen, but at the same time it should retain the water. The medium should be inert, without nutrients. 

The most often used media are expanded clay aggregate, coir peat, sheep wool, perlite, vermiculite, pumice...

There are two main variations – sub-irrigation (water is below the plant root zone) and top irrigation.


Static solution culture  nWmBNVp.jpg

Static solution culture doesn't use a medium, only the nutrient solution.

The plants are in containers such as Mason jars, buckets, tubs or tanks. 

The solution can be aerated but if it is not the solution should be leveled low so that the roots get enough air oxygen. 

Holes are punctured for each plant and the container is covered to protect the solution from light in order to stop algae formation. 

The nutrients are changed either weekly or the nutrient levels are measured by the electrical conductivity meter and when they drop below a certain level, they are changed. Mariotte's bottle is a simple solution for keeping the solution level constant. 

 

Continuous-flow solution culture apCWsTl.jpg

Plants are placed in a container and the nutrient solution flows over the roots. 

The biggest advantage is that the nutrients are in a reservoir which allows for them to be tested for pH and PPM levels and the temperature and nutrients can be easily adjusted. 

The nutrients are used efficiently and the oxygen reaches the roots. 

 

The nutrient film technique

The nutrient film technique (NFT) is an example of continuous flow. 

A very shallow stream (little more than a thin film of water) of the nutrient solution is recirculated past the bare plants roots. The roots receive sufficient amounts of oxygen. 

The NFT system has a slope - 1:100 is recommended but difficult to achieve so 1:30 and 1:40 are used. The flow rate should be 1 l/min and channel length shouldn't exceed 10-15 m (or another nutrient can be placed along the gully to prevent growth reduction). 

In all other systems the change in one of the three factors - water levels, oxygen and nutrients, leads to an imbalance of the other two parameters but continuous-flow solution culture provides an optimal amount of each of these factors. 

On the other hand, a big disadvantage are the circulation interruptions since plants have very little buffering if the flow is stopped. 

Overall, this is one of the most productive techniques. 

 

Aeroponics ca0pscz.jpg

The roots are kept in a mist or aerosol of the nutrient solution - continuously or discontinuously, without a medium. 

Since the roots are in air, the main advantage of this system is excellent aeration. Additionally, the microenvironment can be very precisely controlled. 

The disadvantage is that some plants become waterlogged as they cannot survive for too long in water.

All the oxygen and carbon are received through the roots, stems and leaves so the growth is accelerated. Moreover, the plants need much less nutrients. 

Plants will not suffer the transplant shock when transplanted to soil. 

 

Passive sub-irrigation

Also known as passive hydroponics or semi-hydroponics. 

Plants are in an inert porous medium. Water and nutrients are transported to the roots by capilary action from a separate reservoir, ensuring constant supply. 

Root rot is reduced and the air is humid due to evaporations. 

This is suitable for slow-growing plants. 

 

Ebb and flow XnD1E4A.jpg

Ebb and flow or flood and drain sub-irrigation contains of a tray above a nutrient solution. At specific time intervals a pump fills the upper tray with the nutrient solution and afterwards the solution drains back to the reservoir. This way plants regularly nutrients and have good aeration. 

 

Run to waste 6NlJvBD.png

Also called the Bengal system. 

The nutrient solution is periodically applied to the medium surface at regular intervals, often manually. 

It is mostly used for commercial production of large plants such as tomatoes, cucumber, and peppers. 

 

Deep water culture gKKARJo.jpg

The roots are submerged in an oxygenated (by an air pump) nutrient solution which is in buckets or large containers while the plant is in a net pot. 

An airstone (porous stone) helps with aeration as it gradually releases the air into the water. 

 

Top-fed deep water culture

A highly oxygenated nutrient solution is directly delivered to the root zone. The solution is pumped from the reservoir up to the roots and then runs back down into the reservoir. The airstone and the pump run the whole day. 

This method shows increased growth during the first few weeks.

 

Rotary aN6IjWK.jpg

A rotary hydroponic garden is a round frame in which the entire plant growth circle happens. 

Usually it makes a turn per hour and in the center of the rotary is light of a high intensity to compensate for sunlight. As the rotary turns the plants get water and nutrients. 

Plants mature faster as they are fighting against gravity. 

This system has a small footprint and allows a lot of plants to be grown in a small area. 


The nutrients should be adjusted for each plant variety to satisfy the Liebig's law of the minimum, which states that growth is not affected by the total amount of the available resources but by the most limiting factor, the scarcest resource. 

 

Inorganic hydroponic solutions are different than soil chemistry: 
•    they do not have cation-exchange capacity which means pH and nutrient concentrations can change much faster 
•    the pH is easily affected by the imbalance of counterions in the solution caused by selective absorption. Therefore, the plants may not absorb nutrients of similar ionic charge 
•    nutrients, such as iron, can precipitate from the solution and become unavailable to plants 

The pH needs to be regularly adjusted.   (Read about water pH adjustments here ) 
 

Organic hydroponic solutions are able to completely replace the inorganic compounds in conventional hydroponics. However, this brings some challenges: 
•    organic fertilizers are highly variable in their nutritional compositions 
•    disease transmission since organic fertilizers are often animal byproducts 
•    they can clog substrates or other growing equipment 
•    they degrade to emit foul odors 

 

Installing the hydroponics equipment may be expensive but in the long-run it is profitable. Hydroponics produces horticultural crops where it is impossible to do so. The development and use of controlled environment agriculture and hydroponics is beneficial in many communities and may be the future of feeding the growing world population.
 

More about hydroponics: 

 

Related topic: All You Need to Know About Aquaponics

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