Methods to Grow Plants Without Soil

Ponos is the god of labor in Greek mythology and the basis for the Greek word ponics which means hard work. In modern English, ponics is combined with the Greek and Latin words for air and water to describe different methods of soil less agriculture. Photosynthesis in plants requires access to minerals, especially nitrogen, phosphorus and potassium. These nutrients are found naturally in the soil but the soil itself is not required for plant growth. So the common thread in all soil less gardening techniques is the existence of an alternative means via air and water of delivering those minerals directly to the roots of the plants.
Hydro is the Greek word for water and hydroponics literally means "working water." It is the name for the process of growing plants in beds of sand, gravel, or similar supporting material that is flooded with nutrient rich water based solutions. Hydroponics is the oldest of the soil less cultivation methods and goes back 1000s of years to the early Egyptians, Aztecs and Chinese. Of the three soil less gardening methods described in this article, hydroponics is the simplest to implement but also the least efficient. Regardless it enables easy indoor gardening and will typically produce crops on about 20% of the land and use about 10% of the water as traditional agriculture.
Aero is the Greek word for air and aeroponics is the gardening technique for growing plants without anchoring them in soil or a nutrient drenched hydroponic media. In aeroponics, the plants' roots are suspended in air in a chamber and intermittently spayed or misted with nutrient-laden water. The goal is to hold the humidity of the chamber at or close to 100% which exposes the roots to abundant oxygen, CO2 and the necessary nutrients. Aeroponics is a relatively new high tech method of gardening dating back to the end of the 20th century. It is well suited to indoor gardening and can produce crop yields that exceed hydroponics by as much as 40%. It is also more complicated and less forgiving than hydroponics. The wet/dry spray cycles must be consistently timed and crops can be severely damaged or completely lost due to even short electrical power outages or equipment failures.
Aqua is the Latin word for water and aquaponics is the modern practice of growing fish and plants in a closed water system utilizing the natural synergistic relationship between these two species. Aquaponics combines hydroponics with aquaculture to create a sustainable food producing process that yields organic fruits and vegetables plus healthy fish populations for either consumption or as ornamental pets.
Aquaculture or fish farming is the growing of aquatic species, such as fish, crayfish and prawns in a controlled environment. A key to the ability to grow healthy fish in an aquaculture system is to maintain the water quality through the removal of adverse elements produced from fish waste products. As previously stated, hydroponics is growing plants in a solution of water and nutrients. Hydroponic farmers must maintain the level of nutrients in the water as they are consumed by the plants adding labor and expense to the processes.
Aquaponics utilizes a symbiotic relationship between the two species to provide nutrients for the plants while at the same time sustaining clean water for the fish As they eat and grow fish produce waste that introduce ammonia into the water which is toxic to most aquatic animals. Through a natural multi-step process known as the Nitrogen Cycle, ammonia from fish waste products are transformed by bacteria into nitrates that are a source of the nutrients that are needed by plants. The plants feed on these nutrients and filter and clean the water for the fish. By combining these two older systems, aquaponics is the ideal answer to a fish framers problem of disposing nutrient rich water and a hydroponic growers need for nutrient rich water.