REAL-TIME MEASUREMENT OF DRAINAGE FROM POT-IN-POT CONTAINER NURSERIES

In pot-in-pot nursery production, information on the amount of drainage water loss from the pots due to irrigation and rainfall is beneficial to improving irrigation water use efficiency and optimizing nutrition management. An experimental field site was established to determine drainage water loss from pot-in-pot container nurseries with micro-irrigation. The site consisted of 50 container-grown trees, 10 tipping-bucket rain gauge units, and a portable weather station. Rain gauge units were calibrated four different ways to determine repeatability and reliability for real-time measurement of the drainage water. Volume of water was calculated from the product of number of tips and volume per tip. Accuracy of measurements was verified by the amount of drainage water collected weekly in collection buckets located under rain gauge units for various irrigation applications and rainfall events. The maximum difference in the weekly amount of drainage water collected with the collection buckets and measured with the rain gauge units was 1.215 L (or 5.3% error) when the daily irrigation application to five trees was 15.5 L. The system reported real-time measurement of drainage water due to irrigation and rainfall, and provided a research tool to evaluate strategies for nurseries to better manage irrigation schedules.