Hydroponics in Food Production

In an earlier article, I wrote about my interest in a type of horticulture known as aquaponics. I had always heard about its cousin, hydroponics, and only had a very basic understanding about how it works, so I decided to look into a little more and see what its all about.

What is Hydroponics? Hydroponics is a type of horticulture in which the plant is grown in sand, gravel, or liquid as opposed to soil, where nutrients are artificially added to the water.

Hydroponic systems grow plants in a medium other than soil, typically in floating rafts, but could also be in growing beds of sand, gravel, or expanded clay/shale. Instead of the plants getting their nutrients from naturally occurring compost in the soil, a mineral nutrient solution is added to the water, making the nutrient consumption of the plant more efficient, which can lead to a higher yield than would be normal for soil growing.

What Types of Hydroponics Systems are there?

There are several different design techniques used in hydroponics systems, including the nutrient film technique, wicking system, ebb and flow (flood and drain), water culture, drip system, and aeroponics.

The nutrient film technique (NFT) is primarily used in large commercial set-ups, but can be use with home growers also. This type of system incorporates plants, which are suspended in a channel/gully, commonly built from a PVC pipe with a hole cut in it, with the nutrient rich water flowing underneath. The water flow in these systems is slow, and has a shallow depth, such as that water primarily only reaches the tips of the roots. This technique is best suited for smaller quick growing plants such as different types of lettuce.

Wicking systems are designed for the plants to never fully touch the water. The plants are suspended in a grow bed/raft above a container of nutrient rich water, with a wicking material suspended between the two. This material could be coco coir, vermiculite, or perlite, and serves to slowly draw the water from the tank to the plant. The plus side to this system is that no electricity is needed for water pumps. The downside is that the larger plants which need more nutrients will not grow in this set-up. Plants like lettuce and herbs do well in this type of system.

Plants that require more nutrients do better in an ebb and flow system, or as it’s sometimes called, flood and drain, and this system is exactly what it sounds like. Nutrient rich water is pumped into a grow bed until it reaches near the top of the root system (flooded), and then a mechanism drains it off back into a sump tank, which will then again start to be pumped back into the grow bed to flood again.

Probably the simplest of the hydroponic designs is the water culture system. This design incorporates plants that are suspended in the water by a raft, and the roots stay mostly submerged all of the time. In other systems, the roots are either never fully submerged in water, or only submerged for short periods of time, which allows them plenty of time to intake carbon dioxide. In deep-water systems, air stones are used to make sure that the nutrient rich water also as plenty of air mixed in.

For plants with larger root systems, a drip system can be used. This type of system is exactly what it sounds like; it slowly drips water on the plants. This can be beneficial in systems with larger plants because less water is needed. While this design still needs a sump tank with a water pump, there are multiple ways these systems can be set up.

So fare we’ve talked about different ways to suspend plant roots over water, but this next concept of hydroponics is a bit different, and maybe the most technical. In an aeroponic system, the plants are suspended in a dry tank, and the roots are sprayed with a fine mist of the nutrient water in regular short bursts, allowing the roots to get the most air of any system.

What is used in Hydroponic Nutrient Solutions?

The key component that makes hydroponic systems work is the nutrients that are added to the systems water. These replace the naturally occurring elements that plants would normally absorb from soil, but in a controlled environment. The right mixture of the nutrients in a hydroponic system would mean that the plants would be getting a much more beneficial mix than what is typically found in most soil environments.

The man nutrients used in a hydroponic mix are nitrogen (N), potassium (K), phosphorus (P), calcium (Ca), magnesium (mg), sulfur (S), iron (Fe), manganese (Mn), copper (Cu), zinc (Zn), molybdenum (mo), boron (B) and chlorine (Cl). Some blends also contain nickel (Ni), cobalt (Co), silica (Si), or selenium (Se).

You can buy nutrient premixes, or if you’re experienced/brave enough, make your own, but chances are you will at some point experience different symptoms from your plants that will point to them being unhealthy, and you can use that to determine what nutrient is deficient in the mix.

For example, plants lacking in nitrogen can be short, with pale yellow-green leaves. Plants deficient in phosphorus have stunted growth, and are dark green in color, while a system lacking in iron may have green leaves but yellowing veins.

A beginner in hydroponics will probably want to stay with a commercially purchased nutrient mix. They can be bought in concentrated form at your local indoor gardening store. It is best, however, to have a list of symptoms and solutions on hand to quickly address any symptoms that may arise.

Don’t confuse regular garden fertilizer with hydroponic nutrients though. They are not the same. Only additive nutrients blended to work in this environment should be used. They are sold in the form of concentrated liquid or powder form, although many find the liquid for easier to measure.

You will need to calculate the right concentration of nutrient to add to your water either way, and that means the correct balance between the store bought premix solutions, combined with the correct amount of any correction necessary.

Manufacturers of the different hydroponics additives have listed suggestions, its best to follow their recommendations.

Since this is meant to be a basic overview, I won’t get into the exact science of the mix, or problem solving here. What is important for you to know as a beginner is that you’ll have to calculate how much of each nutrient is necessary for the size of your system, as well how to recognize potential problems early, and know the solutions(s).

Pro’s and Cons of Hydroponics

Are there any benefits to hydroponics, what are the downfalls of hydroponics? Lets check them out.

Pros
- Grow anywhere, you don’t need fertile ground
- Easier to control what chemicals and nutrients plants receive
- Reduces chemical fertilizer from leaching into the ground water
- Requires less water than traditional ground grown plants
- No tilling, cultivating, or mulching are required
- Year-round growing is possible
- High crop yields
- Less space required
- Requires less space
- Easy harvesting
- Weeds, insects, and pests are less of a problem
Cons
- It isn’t very cheap, initial set-up costs for larger operations are high
- Operating costs are high
- Not all plants grow in this environment
- Mistakes and malfunctions affect plants faster
- Power outages require back up systems to keep plants alive
- You have to constantly monitor nutrients in water
- It’s hard to “Set and Forget”
- Water based micro-organisms can appear
- If disease occurs, all plants will be affected

What Types of Hydroponics Systems are there?

What is used in Hydroponic Nutrient Solutions?

Pro’s and Cons of Hydroponics

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