Field Notes
February 2012: Fazenda Tanguro, Brazil
Research Associate Paul A. Lefebvre recently visited Fazenda Tanguro in the Mato Grosso region of Brazil and the Amazon to continue work started over a year ago. ‘Tanguro Ranch’, as it’s known, is the site of a tropical ecological research station run by the Amazon Environmental Research Institute (IPAM), at which WHRC and other institutions conduct ongoing experiments. You can view Paul's previous field notes from the ranch here.
February 10, 2012
I'm back at Tanguro Ranch to continue the work I began over a year ago, installing moisture sensors in soil pits. Assisted by IPAM field technicians Sebastião (“Bate”) and Sandro, we're taking physical samples of soil from the pit. The bulk density and soil moisture calibration samples we collect will contribute to a site-specific calibration of our moisture sensors, greatly improving the accuracy of measurements.
Bulk density sampling involves taking a sample of soil of a known volume without disturbing the natural integrity and structure of the soil – not always an easy thing to accomplish. The samples we took last January during the rainy season turned into mud pies, and then last July during the dry season, when we sampled three pits, the soil was so hard that a number of samples crumbled before we could bag them. Even worse, in the process we collapsed a portion of a pit wall. Having taken moisture calibration samples at that time as well, I am now taking readings during the wet season to capture the opposite end of the soil moisture range.
Research Associate Paul Lefebvre bagging a bulk density soil sample while standing on a platform at the top of a 10m soil pit.
A tarp stretched over the top of the pit allows us to work through frequent rain showers, but one strong downpour forced me to put off moisture sensor measurements for a while out of fear that a stray splash might find its way into the computer. The soil sampling is slow, plodding work, scraping mud and swatting bugs just to get one more of hundreds of data points, but after awhile I realize that I’m really enjoying myself.
As Sandro sends up samples from the pit, Bate and I process them silently on our little assembly line – improvised from a few plastic grocery bags spread on the ground, the focused, repetitive work of handling the soil becomes a kind of meditation. The best part for me is knowing that this will all lead to an improved understanding of these soils – far more so than we first considered when we began working here. It’s not a typical day in the office, and I don’t mind a bit.
February 14, 2012
Last year I had an interesting experience when I was mobbed by honeybees while installing a datalogger in one of the soil pits. My sweat apparently attracted the bees, and hundreds of them came to feed off the moisture and salt in my shirt over the course of about 30 minutes. I’m a beekeeper at home and have been covered in bees a few times (though only when dressed for it), so I took a few deep breaths and told myself I’d be all right as long as I didn’t react. At the time I concentrated on making slow deliberate movements to avoid accidentally crushing one. When I finished my work, I walked slowly away and let the bees leave me naturally, congratulating myself for keeping my cool.
On left is the datalogger after termites got into it, at right are soil samples ready to go to town where they'll be dried and weighed to calculate bulk density.
I just learned that I was probably working a bit hastily that day. The bees found me while I was sealing the 20 or so cables passing through the conduit into the weatherproof enclosure box. I could blame it on my reluctance to bend over to get a good look for fear of crushing a bee, but I didn’t stuff enough electrical putty between the cables to completely seal the gaps. A colony of termites found a nice highway up between the cables right into the nice, dry datalogger enclosure – the perfect home! That much-used line, “If you build it, they will come,” is very true in a tropical setting. Set up a new structure of any size, and birds, bugs and other animals will soon arrive to check it out. There will always be some that find a crevice or gap.
Termites and their byproducts are not very good for delicate electronic equipment and they made a mess of the instruments inside the box. Luckily I had spares of everything, so this afternoon I swapped out the whole mess and cleaned up the old box and its equipment. Nothing was damaged and no data were lost, but it was a pretty disgusting chore. We live and learn …
