AN AUTONOMOUS, LOW-COST, AND PORTABLE LYSIMETER FOR USE IN A GREENHOUSE SYSTEM

Abstract

A lysimeter is a device which measures pH, electrical conductivity (EC), and drainage rate of a row of plants in a greenhouse. Lysimeters will typically cost anywhere between $15,000 and $20,000 per unit and are generally engineered for high-tech, large, commercial greenhouses. This is problematic for small to medium greenhouses which can neither afford such an expensive unit nor need one with so much functionality. To fill this need, we have designed an autonomous, low-cost, and portable lysimeter for use in a greenhouse. The design consists of a divided tank, each side equipped with a pH probe, EC probe, fluid level sensor, and pump. The duality of the tank allows for monitoring of not only the solution that drains out of the plants, but also the solution that is being given to the plants. After data is collected, the solutions are pumped out of the system and into a drainage channel allowing for the solution to be recycled. Software was developed to autonomously collect data from the sensors at appropriate time intervals, process the data, and display the data in a user-friendly manner. A Raspberry Pi serves as the microcontroller and data storage unit allowing for a historical log of data.