Data loggers: To Bury, or Not To Bury
Globally, the number one reason for data loggers to fail is flooding. Yet, scientists continue to try to find ways to bury their data loggers to avoid constantly removing them for cultivation, spraying, and harvest. Chris Chambers, head of Sales and Support at METER always advises against it. He warns, “Almost all natural systems, even arid ones, will saturate at least once or twice a year—and it only takes once.” Still…there are innovative scientists who have had some success.
Radu Carcoana, research specialist and Dr. Aaron Daigh, assistant professor at North Dakota State University, use paint cans to completely seal their data loggers before burying. They drill ports for the sensor cables, seal them up, and when they need to collect data, they dig up the cans. Chambers comments, “So far it looks promising, but we had a long discussion about the consequences of getting any water in those cans. I don’t know what they were sealing the ports with, but they were pretty confident that they could even dunk their paint cans under water.” The North Dakota research team buried the paint cans last fall, and Chambers says he’s reserving judgment until spring. Radu comments, “The picture above is just the concept. The story will continue in April when we see the North Dakota winter toll.” (See update).
Chambers has good reason for his skepticism. If a logger gets saturated even once, its life will be short. And even if it doesn’t get completely flooded, there is still risk. As water gets into the enclosure that encases the logger, the resulting high humidity can damage the instrument. Chambers says, “If loggers that are mounted on a post get a small amount condensation or water inside, they’ll be fine. But the buried ones have no escape route for water vapor. If they get wet or are exposed to water vapor even once, they are going to fail. We’ve seen horror stories time and time again. It’s just not a good environment for electronics.”
Chambers likes to relate a cautionary tale about some scientists in Seattle, who buried their data loggers in five-gallon buckets with lids. They taped their loggers to the lid, but when they dug the buckets up, they were half full of water, and the loggers were dead. This is because as the buckets filled with water, the loggers were continuously exposed to water-condensing conditions. After the loggers were repaired, the scientists re-buried them. But, six weeks later, their buckets were again half full of water, and their loggers were dead.
One Success Story So Far
There is one innovative group at Washington State University, however, who can be considered successful. Postdoctoral research associate Caley Gasch decided she wanted to bury data loggers in the Cook Agricultural Farm, an actively managed field, so they weren’t constantly taking down loggers and causing large gaps in their data.
Next week: Find out how she was able to solve many of the problems that prevent successful deployment of data loggers underground.
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At this date I am in the position to update the first report (above) from March 7, 2016, refering to “The Good” – chapter of this blog.
In May this year, we un-burried 18 units (Em50 and 4 5TMs per unit) left in field since Nov 2016, over 6 month.
In regard to moisture/water – we found only 3 cans with water, due to pure installation technic for that specific unit. The othe 15 units were bone dry.
In regard to data recording/recovery – all data for 6 month, 30′ reading/recording interval was recovered.
In regard to power, the batteries were good and I left them there. The power budget was more than enough for 30′ sensor reading interval. All batteries were over 90% good.
We installed 18 more units right away on the 3rd farm field, right after planting, so we have 36 individual units (~$1,000 value each unit) burried in the ground in the middle of the field, planted with corn and soybean.
The first 12 units were accessed and data downloaded (all of it since May) batteries and the other accessories replaced and then burried back. Only one unit out of 12 had an issue, battery expoding in the can, and the Em50 had to be sent back to Decagon for repair. The other 24 units will have to be accessed this week and next, weather permiting.
We continue to monitor and retrieve the data. The system works very well, considering the installation be done responsibly, with attention for details.
There are improvements that can be very helpful, in order to have this method become a standard in soil research. We are still using paint cans and other improvised materials. A waterproof designed container will be a huge step ahead.