A Comprehensive Guide to Sweet Briar College’s Greenhouse Hydroponics System

Completed in the summer of 2020, Sweet Briar College’s 26,000 square foot greenhouse is home to a variety of vegetables, providing fresh food for the campus dining hall as well as giving students the opportunity to learn about food sustainability. The current horticulture practices in the greenhouse are functional, but growth rates and processing could be improved with a hydroponic system. Hydroponics is a subset of horticulture in which plants are rooted in nutrient-rich water rather than soil. A hydroponics system would not only serve as an educational opportunity for Sweet Briar’s environmental science students but would also allow for the experimentation of a variety of new plants and growing methods. Some other benefits of a hydroponic system include a significant decrease in water waste, reduced need for pesticides and herbicides, and more efficient use of space.Through extensive research and compliance with customer specifications, we determined that using a Nutrient Film Technique with an A-frame design would be the best option for the Sweet Briar College greenhouse. The NFT water flow method is one of the most respected in the field of hydroponics, as it is typically extremely reliable and user-friendly. A thin film of nutrient-laden water gently passes over the roots of the system, allowing the plant to absorb as needed. Incorporating this technique with an A-frame design would allow for the best use of space while still allowing each plant to receive optimal sunlight as compared to other vertically designed hydroponic systems. By incorporating microcontrollers and sensors to monitor the water level, pH, and electrical conductivity in the reservoir, our system will be able to dispense nutrient solution and water as needed. We plan to measure and track plant growth and survivability based on both new plant growth as well as fruit/vegetable production with the goal of exceeding that of standard soil-grown plants of the same variety and anticipate having results by April 2021. We would also like to track system water loss, either from leaks, evaporation, or absorption, by monitoring the main water reservoirs with the goal of 75% efficiency over the course of a month. Finally, we would like to measure the amount of light the plants are getting throughout the day, using either a photoresistor and microcontroller or a lux meter, to determine if additional synthetic lighting options would be beneficial to the system. We plan to have the system fully functioning and operable by May 2021.