Automated System for Collecting Multiple, Sequential Samples from Soil Water Percolation Samplers under Continuous Vacuum

Abstract

Manually collecting a series of sequential, discrete water samples from soil water percolation samplers, or similar devices that withdraw water from unsaturated porous media under continuous vacuum, is a logistical challenge, though the resulting collection can provide valuable information on the dynamics present in both laboratory and field studies. This article describes a sequential tension autosampler (STAS) that executes such sampling automatically. The STAS operates on 12 volts direct current (VDC) and can be adapted for laboratory and field applications. A data logger was programmed to operate a series of solenoid valves, which direct soil water collected under tension to seven individual collection bottles. The number of sequential samples, sample period, start time, and between‐sample interval are specified by the user. The operator only need to attend the system periodically to transfer water samples to storage vials and program the next sampling sequence. In a laboratory study, the apparatus successfully collected samples overnight or over several days.

Keywords:

• Automation
• lysimeters
• percolation
• sample fractionator
• seepage
• soil water
• tension lysimeter
• vacuum extraction

Acknowledgments

I thank Masaroni Katsuyama, Dennis Kincaid, and Lloyd Owens for their constructive comments on an earlier draft of the manuscript.

Notes

¹Mention of trademarks, proprietary products, or vendors does not constitute a guarantee or warranty of the product by the USDA Agricultural Research Service and does not imply its approval to the exclusion of other products or vendors that may also be suitable.