Design and Application of a NFT Cultivation Tester

Nutrient film technique (NFT) provides the advantages of rendering consistent high output and easy production scale-upin conducting experiments on plant cultivation. In order to maximizeprocess efficiency and develop potentials. NFT Cultivation Tester was developed. The tester consisted of a fertilizer mixing barrel for blending and storing nutrient solution, a group of cultivation tanks with exchangable covers, an irrigation pump, a mixing pump, a solenoid valve, an electric drain valve, a UV sterilizer, and a temperature sensor, as well as EC, pH and electrical control systems.All components were mounted on a sturdy stainless steel frame. Like the mainstream NFT vegetable cultivation systems, the tester also allowed the nutrient solution held in the mixing barrel run through a series of parallel cultivation tanks, a filter, andan online UV sterilizer before returning to the barrel by a controlled irrigation pump. As the core of electrical control system, HMI read ambient temperature, humidity, illumination, as well as the temperature, EC, and pH of the nutrient solution by various sensors. With the communication protocol, RS485/MODBUS, the operations of the peripheral equipment were controlled with input output boards. The software package contained the automatic functions including fertilizer mixing, barrel cleaning, tank washing, water replenishment, irrigationplanning, monitoring/alarm, and data logging. The system was also equipped with manual irrigation and emergency stop functions. Spacing and number of plants for testing could be easily adjusted by using cultivation tank covers of varied spacings and holes. A typical test might use 8 tanks with covers having holes sapced 20 cm center-to-center apart to handle 200 plants simultaneously for 8 treatments. Any experiment for crop variety selection and/or disease resistance could be efficiently conducted in a NFT Cultivation Tester. By using multiple Testers, optimizations on nutrient solution formulation, irrigation parameters, etc. might be conducted without difficulty.