With an increase in focus on urban cultivation and high value crop cultivation, hydroponics is becoming more and more popular especially amongst urban dwellers. Hydroponics is seen as one way to generate a constant supply of fresh vegetables, fruits, condiments and even medicinal herbs throughout the year. From a macro perspective, hydroponics helps localize food systems in cities, where food is typically imported into cities long distances from the countryside or from other countries.
From an engineering standpoint, developing an effective hydroponics system necessitates the need to develop several tightly controlled feedback systems that help ensure optimal plant growth. These feedback systems include maintaining optimal plant hydration, light exposure, nutrient delivery, oxygenation levels and temperature. With widespread access to cheap microcontrollers and a plethora of sensors - developing robust hydroponics systems is well within the reach of individuals looking to set up small scale systems.
Hydroponics has 6 main techniques: Wick, Water Culture, Ebb & Flow, Nutrient Film Transfer (NFT), Drip, and Aeroponics.
The Wick and Water Culture techniques essentially revolve around keeping the plants in constant contact with the growth solution and relying on capillary action and the plant’s roots to take up water and nutrients as needed. These systems are extremely simple to set up, and are the standard choice amongst first time growers. On the other hand, plants in these systems often suffer from poor root oxygenation and root rot due to the being immersed in water all the time. The only control systems needed here involve monitoring the pH levels of the growth solution to ensure that the water quality is well regulated.
The NFT technique involves pumping a thin layer of water continuously at the roots of the plants. While these systems promote exceptionally rapid plant growth, they require seedlings to be transplanted into the system. Coupled with higher space and starting costs, NFT systems are extremely popular amongst commercial growers, but less suitable for compact, indoor applications.
The Aeroponics, Drip and Ebb & Flow techniques all revolve around periodically wetting plant roots. As compared to the systems discussed above, additional control systems are needed here to monitor the plant’s hydration levels and dynamically adjust the periodicity of the wetting cycles. While the Drip and Ebb & Flow techniques involve pumping water, the Aeroponics technique aerosolizes the plant growth medium and sprays it directly on the plant’s roots.
The Aeroponics method is best suited for plants that require low amounts of water whilst the Drip method is best suited for plants that need substantial amounts of water. Among the three, the Ebb & Flow technique has been proven to be the most versatile in promoting growth in a wide variety of plants. Even so, all three systems promote rapid plant growth whilst maintaining a compact footprint - making them suitable for indoor applications.
As a whole, from the perspective of developing small scale urban growing solutions, the Ebb & Grow technique offers the optimal of compactness, growth and cost efficacy and versatility. Designing a rudimentary Ebb & Grow system is likely a fairly trivial effort, especially given the widespread availability of cheap microcontrollers and sensors. The real difficulty in developing any hydroponics system, irregardless of scale, comes in tuning the system to achieving optimal growth. Being able to cater for conditions that are often suboptimal or downright hostile requires innovative designs and extensive testing.
Even with the challenges that beckon, it’s likely that the popularity of urban hydroponics will continue to increase, especially if current societal trends continue. Beyond urban farming, hydroponics is being heavily investigated by NASA to create closed loop farms that utilize human waste and carbon dioxide to produce food, water and oxygen for astronauts in space.