What are lysimeters?
Lysimeters are delineated soil columns with a known volume and surface area. The column can be either filled manually with disturbed soil material or be equipped with an undisturbed soil monolith excavated from the site of investigation. Lysimeter experiments can be either conducted in the laboratory (laboratory lysimeter) or in the field (field lysimeter). Experiments using lysimeters have been carried out for more than 200 years (Goss und Ehlers, 2009). The lysimeter technique has been improved constantly and has been applied to even more complex research topics ever since.
Application of lysimeters
Lysimeter experiments are a convenient method to determine water balance variables. In combination with precipitation measurements it is possible to directly calculate the evapotranspiration rate by using the recorded mass change of a weighable lysimeter. Lysimeter experiments are utilized to investigate water balances of ecosystems or crop water use of rain fed crops. Lysimeters equipped with a leachate collecting system allow the quantitative and qualitative (in the laboratory) investigation of the seepage water.
Further, lysimeters can be equipped with additional sensors such as tensiometers, soil moisture probes, thermometers, and suction probes which allow the investigation of the functioning and mechanisms of ecosystems. The results can be transferred from small to large scales. Due to the possibility of long term field investigations under given site conditions, lysimeter experiments can be used to derive statements about the water balance under certain climate scenarios. A comparison of several identical lysimeters in areas with different weathering conditions or a comparison of different soil types or different vegetation under the same weather conditions over a longer time period is also a common research goal. These investigations provide the foundation for many models to estimate the effect of climate change, the spread of contamination in the soil or the success of remediation measures.
Fields of application
Lysimeter experiments can be either conducted in the laboratory or in the field. Typical areas of applications are agricultural sites, forest sites, landfill sites, post-mine landscapes as well as contaminated sites in need of rehabilitation. The combination of several lysimeters is recommended for statistically verified statements. Up to 4 lysimeters can be put together in autonomous UGT-lysimeter stations made of PE-HD. For larger test setups several stations can be combined or large lysimeter systems erected with concrete basements are also possible. The size of the soil monoliths can vary from very small dimensions (95 cm² in area, less than 1 m deep) to large lysimeters (2 m² in area, up to 3.5 m deep). For location based research targets it is necessary to investigate undisturbed soil monoliths. The patented UGT-Excavation Technology provides a non-destructive excavation of the soil monolith with minimal impact on the environment.
Lysimeter experiments can also be conducted in the laboratory. Under defined and controlled boundary conditions an investigation of the behavior of natural soils or vegetations under special environmental conditions, as well as physical/hydrological soil properties of manually imported soils or processes of (contaminant) substance distribution, relocation and leaching is possible.
Goss, M.J. und Ehlers, W., 2009: The role of lysimeters in the development of our understanding of soil water and nutrient dynamics in ecosystems. Soil Use and Management, 25, 213-223.