Hydroponic cultivation system

1. A plant cultivation system which hydroponically cultivates plants using a liquid fertilizer, the plant cultivation system comprising:

a first floor including a first surface, the first surface being configured to cover each of a first installation area where a first plant cultivation shelf is installed, a second installation area where a second plant cultivation shelf is installed, and a passage area where a passage between the first plant cultivation shelf and the second plant cultivation shelf is disposed, and the first floor having no air vent holes;

a second floor including a second surface differing from the first surface, the second floor having air vent holes; and

an air-conditioning unit configured to circulate air from a ceiling having air supply holes to the air vent holes in the second floor,

wherein an exhaust tube is connected at one end to a suction part of the air-conditioning unit and connected at an opposite end to an exhaust path communicating with the air vent holes in the second floor, the exhaust tube being disposed under the second floor at a position closer to the second surface than the first surface;

wherein the first floor may be selectively placed on the second floor to selectively close the air vent holes of the second floor,

wherein the first plant cultivation shelf in which first plants are cultivated using a first liquid fertilizer faces, via the passage, the second plant cultivation shelf in which second plants are cultivated using a second liquid fertilizer, and

wherein transferring the first plants from the first plant cultivation shelf to the second plant cultivation shelf by an operator in the passage enables changing of the first liquid fertilizer to the second liquid fertilizer for use in the cultivation of the first plants.

2. The plant cultivation system as claimed in claim 1 , wherein

the first plants are inserted into or removed from the first plant cultivation shelf and the second plants are inserted into or removed from the second plant cultivation shelf; and

the plant cultivation system further comprises

a down-flow cleanroom configured to circulate air from the ceiling to the exhaust tube via the air vent holes in the second floor.

3. The plant cultivation system as claimed in claim 1 , wherein

the first plants are cultivated using the first liquid fertilizer when the first plants are placed on the first plant cultivation shelf, and the second plants are cultivated using the second liquid fertilizer when the second plants are placed on the second plant cultivation shelf.

4. The plant cultivation system as claimed in claim 3 , wherein

the first liquid fertilizer includes a component differing from a component included in the second liquid fertilizer.

5. The plant cultivation system as claimed in claim 1 , wherein

the second surface is disposed approximately parallel to a direction from the first plant cultivation shelf toward the second plant cultivation shelf.

6. The plant cultivation system as claimed in claim 1 , wherein

the first plant cultivation shelf cultivates the first plants at timing differing from timing at which the second plant cultivation shelf cultivates the second plants in a growth period of one plant.

7. The plant cultivation system as claimed in claim 1 , wherein

the first plant cultivation shelf includes a first lighting device, and the second plant cultivation shelf includes a second lighting device, and wherein

the second lighting device is turned off while the first lighting device is turned on.