A WEIGHING LYSIMETER FOR DETERMINING WATER-LOSS IN RED SPRUCE SAPLINGS (PICEA-RUBENS SARG)

A relatively simple, economical, and sensitive load cell weighing lysimeter system was developed for determining water use by 1-1.5 m tall red spruce (Picea rubens Sarg.) trees exposed in the field to ozone and simulated acidic precipitation in open-top chambers. The lysimeters have been operating successfully in the field for the past two growing seasons. They are used to measure moisture losses by evapotranspiration and deposition of simulated acidic precipitation to tree and soil. The lysimeter was constructed of materials that are sturdy, corrosion resistant, and readily available from commercial sources. Each lysimeter has a total capacity of 681 kg (1500 lbs) based on a rated load cell capacity of 227 kg (500 lbs); however, an increased capacity is attainable if load cells are overloaded within the manufacturer's safe rated limits. The completed system has a maximum sensitivity of 18 g, which corresponds to 0.023 mm water based on a soil surface area of 7854 cm2; however practical use limits the system to an accuracy of about 100 g, which corresponds to 0.13 mm equivalent water depth. © 1990.