This thesis presents the design, implementation, and experimental validation of an IoT, high-precision, modular weighing lysimeter to be used inside a plant growth chamber. Weighing lysimeters are used to precisely quantify plant water losses (evapotranspiration) and growth by monitoring the changes in the weight of the pots used to grow them. The requirements called for a system capable of monitoring four pots concurrently and transmitting the data to a central server using a Raspberry Pi single-board computer. The proposed architecture couples a commercial mechanical structure (CELMI LP7611 single-cell load frame) with two custom analog front-end alternatives, based respectively on the Nau7802 IC and the ZSSC3224 IC, which digitize the Wheatstone-bridge load-cell analog signals.