Data Logging in a Hydroponic Greenhouse

George Mason University’s hydroponic greenhouse and the Patriot Green Fund requested an irrigation data logging system to track how weather conditions affect the frequency at which plants need to be watered. A prototype system was created, and tested in the greenhouse. The initial prototype was found to have significant issues, and was brought back to the lab for modification. Upon testing in the lab, it was found that the sensors worked as expected; further testing is required to determine why this is. This project has wide implications in the field of sustainability, as it could be used in medium- and small-scale hydroponics operations across the world.

Hello everyone, my name is McKenna Olsen, and my teammates German Kuznetsov, Franklin Farrel, and I are working on a project called Greenhouse Irrigation Data Logging. We’re supervised by Nathalia Peixoto with OSCAR’s Summer Team Impact Projects, Sarah d’Alexander with the Patriot Green Fund, and Donielle Nolan with the President’s Park Hydroponic Greenhouse.

We’ve spent 10 weeks of this summer trying to create a system to log data on temperature, humidity, and moisture levels in the President’s Park Greenhouse. The ultimate goal of this project is to discover how weather conditions affect moisture levels in the hydroponic trays and therefore how often plants in the greenhouse need to be watered.

Our initial goal was to create a system that would both log data and use that data to determine the intervals at which watering should occur, however we quickly realized that we were getting ahead of ourselves. No one had collected data of this sort in the greenhouse before, so we didn’t have a baseline to work off of. So, we set out to create that baseline for other students and staff to work with in the future.

Now, filming from the greenhouse, I wanted to show y’all the system we’re working with. This is essential to our project, as whatever we make should integrate seamlessly into what the greenhouse already has. Nutrient-enriched water flows from these bins into the hydroponic trays above, where it reaches the plants – there’s nothing in them now, but during the school year they’ll be overflowing with amaranth, basil, and even sunflower sprouts! The plants get watered about 7 times a day, but due to changes in light, temperature, and humidity, this can end up being either too much or too little. These trays are where we tested our prototype system.

Many plants, particularly young seedlings, are incredibly sensitive to water levels. Overwatering can cause problems such as root rot or disease, and under-watering causes the plants to wilt. Either way, the greenhouse won’t produce as much, and will earn less money off the product.

Our prototype system, pictured earlier and tested here in the greenhouse, allowed us to learn a lot about collecting data in the greenhouse; we learned that we would have to take into account waterproofing, the chemical properties of the nutrient solution used to water the plants so as to prevent corroding of our equipment, and even things as simple as where to place the system so it wouldn’t be disturbed, or where to plug it in.

Unfortunately, we did not acquire any viable data from our first prototype upon testing in the greenhouse (however, we did acquire some useful data from commercial sensors we had placed in the greenhouse for comparison). We found that, as we expected, temperature in the greenhouse rose and humidity dropped throughout the day, meaning that water would likely evaporate faster during these hours (from about 10AM to 4PM), and slower at other times. This would indicate that the watering schedule could be altered to help accommodate this difference, although more data should be collected on differing weather conditions and during different seasons. Rain, snow, cold snaps, cloud cover and wind – there are innumerable ways all of these conditions could affect the data collected.

We hope that the work we’ve done this summer provides a platform for other students, staff, and faculty to collect more data and improve upon the system we’ve designed. We believe that there are numerous potential uses for this system, from allowing staff to monitor moisture levels when the greenhouse is closed, to helping students design even more helpful systems for the greenhouse.

We would like to sincerely thank OSCAR, the president’s park greenhouse, and the patriot green fund for allowing us the opportunity to work on this project.