History of Hydroponics
Hydroponics is a farming method without soil.
1600s to WWII
It has a long and interesting history all the way back to 1600s with initial research set the stage for hydroponic development. Most of the research was being conducted without soil. Hydroponics became increasingly popular during and after World War II as island agriculture became increasingly important to the military during war.
1960s to 1990s
With the invention of plastic in the 1960s, hydroponics took off. Plastic enabled an entire agricultural revolution because farmers were now able to do controlled-environment agriculture. They were able to create films and cover greenhouses with them and protect their crops, which is a key component of most hydroponic operations. They have to be able to protect their crops because, without soil, their plants are more exposed and they get the most out of their hydroponics when they can exert a very fine level of control.
The advent of plastics enabled hydroponics to boom.
The techniques accelerated very quickly during the ’60s and ’70s. Controllers and nutrient injectors arrived in the 1980’s and the 1990’s. The entrance and integration of sensors into systems meant more automated dosing systems, automated control systems, and environmental control systems for the greenhouse.
Matching crops to technique
Determine the type of crops to grow and match hydroponics technique to lower risk management and increase efficiency.
Good for leafy green vegetables, herbs
Bato bucket, Dutch bucket
Good for tomatoes, cucumbers, dwarf fruit tree, etc..
The most common hydroponics method are:
Deep Water Culture (DWC)
Suspend the roots into a solution of nutrient-rich, oxygenated water.
Nutrient Film Technique (NFT)
Place plants in channels where a shallow stream of water containing diluted nutrient will re-circulated pass the bare roots.
EBB and Flow (Flood and Drain)
Place growing media such as LECA balls in container which helps to anchor the roots and functions as a temporary reserve of water and solvent mineral nutrient. Supply tank with nutrient will be placed under the container and periodically pump and flood the container for about 5-10mins cycle. Water will flow back to the supply tank by gravity.
Dutch Bucket Drip Method
Used water pump to pump nutrient-rich water to emitters to drip directly onto the plants. Solutions will then flow back to the reservoir.
Hydroponics Measurement and Management
Electrical Conductivity (EC)
It is a measurement of salt content in water. Nutrients are mineral with charged ions. A gross measurement of the total amount of inorganic (not carbon-based) solutes in that solution, usually measured in a conductivity measurement over a distance. Differences in EC over time tells us the rate at which the plants are absorbing fertilizer and when we need to add more. EC is crops specific.
EC and Water Demand
EC directly impacts the ability of the plants to take up water. Osmosis is the movement of molecules through a semi-permeable membrane due to differing concentrations. Molecules tend to move from areas of lower concentration to areas of higher concentration—this rule is used in nature all the time, and osmosis by plants is one of them. Plants perform osmosis in the roots by taking advantage of the differing concentrations between the solution and the inside of the root. The ability of the plant to do this (its osmotic potential) differs when the concentrations differ.
For the plant to draw water out of the solution, there has to be osmotic potential; the concentration of ions inside of the root has to be higher than the concentration of ions outside of the root. If the EC is too high, the difference between the two concentrations won’t be big enough for osmosis to take place, and the plant will fail to take up water. This is called drought stress.
EC and Plant Nutrient Consumption
There are a few rules to be aware of when it comes to nutrient management.
- Plants do not consume nutrients at a consistent rate.
- Plants sometimes engage in “luxury consumption”.
- Plants will take up more of one nutrient than another, leaving your solution unbalanced.
- Plants take up nutrients actively (pumping, usually) or passively (flow). Understanding active and passive uptake is important to understanding some deficiencies, like Calcium.
pH is the measurement of acidity.
An important thing to understand about pH is that it impacts the solubility and availability of different nutrients for our plants. This is really important because different plants take up nutrients in different pH ranges, and certain nutrients are only available in specific pH ranges.
The reality is that sometimes plants produce oxygen, sometimes plants consume oxygen. That’s just in the photosynthetic parts of the plants. Down in the roots, they’re not producing oxygen but consuming it. Some plants will transport oxygen down, but that’s very uncommon in crop plants, so we need to supply those roots with really high levels of oxygen. Air pump and water pump will oxygenate the water.
Dissolved oxygen is dependent on temperature, and not in the way you might expect: it’s less soluble at high temperatures and more soluble at low temperatures. That’s an important thing to know when it comes to managing dissolved oxygen. In systems where you’re having a lot more oxygen consumption, running your temperatures a little bit lower can help. In short, water temperature and the volume of moving water can affect dissolved oxygen levels.