A lysimeter system for monitoring soil solution chemistry

Abstract

In northern temperate and boreal zones, long-term sampling of the soil solution using lysimeter systems requires (i) a lysimeter that can be installed with a minimum of soil disturbance, (ii) a lysimeter that is small enough to install in stony soil but large enough to representatively sample the soil solution, (iii) a system with a constant tension that integrates soil solution sample collection over time, and (iv) a system that will not break under freezing conditions. A lysimeter system that meets these requirements was designed, and consists of a lysimeter (a fritted glass plate mounted on a glass casing) connected in series to a sample bottle and a tension-generating unit. The glass casing of the lysimeter has two ports: a drainage port for continuous flow of soil solution to the sample bottle, and an access port that can be used (i) for air entry to facilitate complete sample retrieval, (ii) for cleaning, (iii) for re-wetting the fritted glass plate, or (iv) for winterizing the lysimeter with alcohol. A 1-m hanging water column was used to supply a constant tension of approximately 10 kPa. A potential 93% efficiency rate of sample collection can be achieved, and the systems are capable of sampling soil solution beneath organic horizons, as well as in the rooting zone of mineral horizons. The system is presently being used to evaluate the effects of different harvesting and silvicultural treatments on nutrient cycling processes in the soil. Almost 700 of these lysimeter systems are in use in the Atlantic provinces of Canada. The lysimeters have been functioning satisfactorily for over 10 yr and are suitable for long-term monitoring of the soil solution. Key words: Lysimeter design, soil monitoring methodology, nutrient cycling