Dear Experts on Soil Solution,
I have a question regarding the life span of the tension lysimeters. In Switzerland, our lysimeters still run well; however, I wonder what the “normal” life span of those lysimeters is. For how long do you use your lysimeters and do you see signs of ageing?
Further, I wonder in case of renewal how long it takes for installation effects to flatten out. In Switzerland, the data analysed by Elisabeth showed that it is a good idea to remove the first year. Do you have any other experience?
Thanks for sharing your thoughts!
Best wishes form Switzerland and take care,
Interesting questions, which I think are relevant for all soil solution experts. I could share my personal experience in Flanders (sandy - sandy loam soils), but I am not sure whether there is a general rule of thumb.
With regard to installation effects, I noticed that a period of 3-6 months is often needed before the concentrations of all elements stabilize and reach acceptable values (as compared to the other samplers in the same plot for the same depth). Usually pH, EC and NO3 are elevated in the beginning, sometimes also other elements (NH4, DOC, ...). I agree that these data should be removed. Once the concentrations have stabilized, we pool the water with the other lysimeters installed at the same depth.
Then life span. I noticed that most lysimeters in our plots work well for about 10-15 years (if the tubings and rubber caps are properly maintained and replaced every 1-2 years). Dropping out usually comes with decreasing ability to hold the vacuum (resulting in little or 0 sample quantity). Probably this could be explained by diminishing contact between the porous cup and the surrounding soil, e.g. through disturbance by animals. Maybe also the element concentrations will deviate after a certain period, but I don't have any data there, as our budget is insufficient for analysing the water from each lysimeter separately during its entire lifetime.
I hope it helps.
thanks for the interesting discussion on this topic! We are about to install a new plot including a new tension lysimeter system. I am wondering whether there are techniques to reduce the duration of the initial "transient period" where samples should be discarded due to installation effects. For example, I heard there exists the technique where a mixture of water and soil (from the same plot and depth) is sucked through the lysimeters for some days in the lab, thereby "conditioning" the ceramic heads of the lysimeters. This might reduce effects of ion uptake or ion relatease to/from the ceramic heads of the lysimeters. Of course, this does not reduce effects of soil disturbance during installation. If soil disturbance is the dominant source of problems during the transient phase and thus samples from the first 3 - 12 months have to be discarded anyway, then the time required for conditioning the lysimeters might be better used for other tasks(?). If you have any thoughts on this, please let me know.
Thanks and best regards,