Rooftop Hydroponics Tunnel Farming
The third rooftop garden possibility is rooftop hydroponics . This is where plants are grown in a soil-less medium (peat, sand, gravel, old rubber tires, rockwool, perlite or vermiculite) and fed a special nutrient solution.
Rooftop hydroponics can be the lightest of the three rooftop garden options, and may offer the possibility for faster plant growth (up to two to four times) and increased productivity.
The purest form of hydroponics is water culture, in which a plant’s crown is supported by a thin layer of substrate, while its roots are immersed in a nutrient solution.
Hydroponic systems can be divided generally into two groups – passive and active systems.
Passive systems are the most simple, and the cheapest, requiring only a container with drainage, a tray that holds liquid, and a growing medium. Plants are hand watered with the nutrient solution and soak up the solution via capillary action.
Active systems include “ebb and flow” or “flood and drain,” in which a pump regularly floods the plant tray with nutrient solution, which then drains back into a holding tank.
Various other systems require different growing media and methods of irrigation, but all need to be monitored for pH and nutrient solution strength, since plants have different nutrient requirements during different stages of their growth.
Commercial systems can cost from $100 to several thousand dollars.
Hydroponics can be practiced anywhere, even indoors, with the help of artificial lighting, and no digging or weeding is generally required. Growing conditions are highly controlled, so plants can be provided with the best possible conditions, resulting in better quality, disease-resistant plants with higher yields – commercial tomato growers have reported yields up to 40 times higher per hectare than soil-grown plants.
Types of Plants:
Almost any kind of plant can be grown hydroponically – tomatoes, peppers, rhubarb, cucumbers, squash, snow peas, beans, spinach, lettuce, strawberries, chard, and broccoli are just some examples.
Another technology spin off of hydroponics is aeroponics, where a hydroponic nutrient solution is sprayed onto plant roots dangling in light-proof boxes.
It allows temperate-climate fresh vegetables to be produced economically in tropical and sub-tropical climates.
Aquaponics, on the other hand is the combination of aquaculture and hydroponics. It is the symbiotic cultivation of plants and aquatic animals in a recirculating environment.
Nutrient rich fish water is pumped from the fish tank into gravel beds, where plants growing in the gravel extract the nutrients from the water. The water then drains back into the fish tank cleaned of excess nutrients and freshly oxygenated.
Aquaponic systems do not discharge or exchange water. The systems rely on the natural relationship between the aquatic animals and the plants to maintain the environment. Water is only added to replace water loss from absorption by the plants or evaporation into the air.