A vertical farm is a large tower with multiple levels, each with soil and crops. Dickson Despommier, professor of environmental science at Columbia University, came up with the idea around the turn of the millennium as a solution to rising populations and shrinking availability of virgin farmland. His vertical farm design has 30 stories and is about the size of a city block. The high-rise design would allow the vertical farm to be located in the center of urban areas, eliminating transportation costs.
Despommier claims that 800 million hectares, or 8% of the total landmass of the earth, is currently committed to agriculture. Historically, 15% of this land has been ruined by poor farming practices. Many scientists forsee a food crisis this century unless steps are taken against it. "Horizontal" agriculture, as we may call it, is responsible for the spread of numerous diseases and parasites, such as influenza, rabies, yellow fever, dengue fever, malaria, trypanosomiasis, hookworm, and schistosomiasis, especially in the tropics. To protect the environment and minimize global disease vectors, Despommier suggests we go vertical with our farming operations.
Because a vertical farm would be a tightly controlled environment, high yields could be attained. In the protection of the indoors, continuous farming could occur under a diversity of climatological or ecological circumstances.
A vertical farm would need to be an independently functioning ecosystem, because it would be separated from the outside. Bugs would have to be kept out indefinitely, and plants would need adequate ventilation. Any rotting organic material would need to be recycled or cheaply disposed of. The more efficient the structure, the less maintenance required, and ultimately the greater return on investment for its owners. In the more distant future, the vertical farm could be entirely automated.
Indoor farming has been used before, primarily for low-size crops like herbs and tomatoes, but a vertical farm project would scale that up and allow the production of bigger crops such as wheat. One limitation would be the inability to grow livestock, unless it were highly customized for the indoor environment. In the long term, there is a strong incentive to move away from livestock due to the large amount of food required to feed an animal until it reaches a point at which it can be slaughtered profitably. With success, vertical farm techniques could also be applied to farming in space or on other planets. This idea is often heard in connection with the phrase "urban sustainability".