Research Article
Roberts B, Schnipke D and van
Abstract
Building on existing technology that utilizes capacitance sensors and low-cost microcontrollers, we designed, assembled and tested a self-contained irrigation system for controlling substrate volumetric moisture content in container-grown ornamental plants. In the prototype system described here, compatible software is embedded within the microcontroller, real-time measurements appear on a liquid-crystal display screen, and data are stored on a secure digital card, thereby allowing irrigation threshold settings to be changed without the need for reprogramming the microcontroller. The system components are readily available and affordably priced, making the unit a useful management option for improving irrigation scheduling for growers that do not wish to invest in more costly wireless network systems. In evaluation trials using 5-week-old containerized zinnia seedlings, the automated system reliably controlled irrigation thresholds ranging from 0.155 to 0.425 m3 m-3. During the trial period each threshold was maintained for 5-7 days during which time substrate VMC varied ± 0.04 to ±0.06 m3 m-3, and the volume of water required to sustain each threshold (as calculated from data collected and stored on the system secure digital card) was within 3% of the actual quantity of water collected in plastic containers attached to the same irrigation line.