A Precision Weighing Lysimeter for Row Crop Water Use Studies1
- Joe T. Ritchie and
- Earl Burnett2
A relatively simple and economical weighing lysimeter specifically designed for evaluating hourly row crop water use under dryland conditions has been developed and tested. The lysimeter soil container is 1.83 m (6.0 ft) square by 1.22 m (4.0 ft) deep. This allows a representative rooting profile for two rows of crop spaced 0.92 m (3.0 ft) apart and also allows normal soil shrinkage cracks to form within the soil mass. The thin soil container and retaining tank walls are separated by a 10-mm air gap, resulting in a surface disturbance of only 4.5% of the lysimeter area. Soil water suction at the bottom of the soil container is controlled. A commercially available floor stand tank scale lever assembly is used to transfer up to 600 kg of the total lysimeter weight to a precision strain gauge load cell, the remainder being counter-balanced under the lysimeter. The sensitivity of the system (± 0.025 mm equivalent water weight change) is adequate for short-period evaporative flux measurements. The electrical output signal from the load cell can be measured remotely, minimizing site disturbance. The weighing mechanism has suitable utility for other weighing lysimeter applications.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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