S06 - Session P18 - Analysis of Uniformity in Substrate Moisture Levels among the Replicates within the Same Irrigation Treatment via Soil Moisture Sensor-based Automated Drip Irrigation System

Authors: Sooeon Lee *, Seong Kwang An, Jongyun Kim

Soil moisture sensor-based automated irrigation systems can use water efficiently for sustainable horticultural production. However, a limited number of sensors should represent many other plants due to their expenses, and maintaining uniform moisture levels among the plants within the same irrigation treatment remains uncertain. The objective of the current research was to quantify the uniformity among the subreplicates within the same irrigation treatments at various moisture levels. Sixty-four sweet basils were grown in the soilless substrate with four treatments maintaining volumetric water content (VWC) at 0.2, 0.3, 0.4, and 0.5 m 3 ·m -3 for 2 weeks by the sensor-based automated drip irrigation system. Sixty-four EC-5 sensors continuously measured the VWC of every single pot to quantify the VWC uniformity among the subreplicates within the experimental unit of treatment and block. General plant growth parameters and photosynthetic rates were measured at harvest. To quantify the uniformity of parameters, standard deviation (SD) and relative standard deviation (RSD, expressed in SD divided by the mean) were used. Although the average VWCs of the experimental units were maintained as designated, there was considerable disuniformity in VWC among subreplicates with SD up to 0.078 m 3 ·m -3 . However, there were no significant differences in SD and RSD of VWC according to the different VWC treatments. In growth parameters, plant responses were similar to previous studies with various VWC levels, but SD and RSD among subreplicates showed no significant difference according to the VWC treatments. These results indicate that there was a considerable disuniformity in VWC regardless of moisture levels with the automated drip irrigation system, which replenished water with a little amount of irrigation. Therefore, selecting a representative pot to measure the moisture level to irrigate the whole plot would need scrutiny, and further consideration would be required such as irrigation amount per application or fluctuating irrigation methods to improve production uniformity. This work was supported by KoSFarm IPET (421027-04).