What’s that phrase, a stitch in time saves nine? Field work kind of works that way, too. There’s a lot of time that you sort of feel like isn’t productive enough, but I have to remember to take the long view because if I don’t get your ducks in a row at the beginning it’s wayyyyy more difficult later to try and fix the problem/justify a decision I made. Inevitably I’ll screw a bunch of things up and not have taken care of them before the project started (first rule of field work: accept that for a bunch of the time it’ll be bananas), but the more things that I can guard against the better.
This week was (and next week will be) all about crossing those t’s and dotting those i’s. Luckily, I had a field veteran with me to rock some mentoring and make sure that I didn’t end the week curled up in the fetal position, weeping. This is Paul!
Paul works as a researcher at WHRC and he is awesome. I adore him already. He’s been helping me put together the gas flux chambers and plan out a bunch of the organizational details that I had punted on until I got down here. (What time of day are we going to sample? How are we going to get everything done in the field with two people as efficiently as possible? What kinds of obstacles have other students run into that I should be thinking about? etc.) Paul is a complete treasure trove of wisdom about this sort of stuff. Plus he’s handy and rad and knows tons of science.
First thing we did was build a bunch of nitrogen gas flux chambers. Rod Venterea at UMN came up with this design for his lab and passed it on to me, but a lot of the assembly I waited to get in country to do since the materials packed up smaller as component parts:
(More about Rod and his insanely great lab manager Mike Dolan in a future post I’m going to call “people who saved my butt when I was getting ready to leave for Brazil”… or something like that.)
We also had to go out into the forest and come up with a way to get the chamber bases (i.e. the bottom part of the chamber that we attach the top part to in order to capture the gas fluxes) into the ground as easily as possible. Baxi, one of the many amazing field workers at the ranch, carved this cool board to fit the bases perfectly so all I had to was jump on the thing a few times and, boom, I was ready to do science!
Finally, nitrogen gas fluxes are regulated in large part by temperature and soil water content, plus the amount of nitrogen floating around in the soil that’s available to bacteria. Soil water content we can’t really control, since rain drives it, but what temperature the soil is when sampling we can control – by sampling during the morning (cooler soil) or the afternoon (warmer soil). For this study, I don’t want to look at temperature changes, but I do want to make sure that I’m not sometimes sampling in the morning and sometimes sampling in the afternoon – i.e. I don’t want to introduce a confounding variable into the study. So, I need to have a sense of how much the soil temperature varies over the course of the day so that later I can justify that a sample at 10 am is within roughly the same temperature regime as a sample at 11:30 am.
So we did that! Paul and I (ok, Paul) set up two thermocouples to take the soil temperature every 15 minutes a few inches below the soil surface in a forest plot and in a soybean field. At the same time, I recorded what my analog soil thermometers reported the soil temperature as to make sure that the thermometers didn’t vary from each other and that they were aligned with the thermocouple data.
Happy to report that there were no lemons out of my eight thermometers!
We’ll pick up the thermocouple equipment and download the data on Monday (it’s been running since Thursday) and I’ll get to take a look. Very excited to do so! Aside from letting me get some hands on some sweet data (data!!!!!!), I’ll get to head back into the forest. Yessssssssss!