Saturday Soil Science Story - Oct. 6, 2018

This week has been CRAZY! So I’m going to keep this week’s post fairly brief. Over the weekend, my friend Kelly was in town, so I waited to post my stories until Sunday. I spent the day working in the lab, but my tasks weren’t too glamorous. While I {somewhat} identify as a soil chemist, most of my lab work does not involve mixing chemicals, pouring liquids between beakers, or running machines to get chemical analyses. Rather, most of my time is spent on preparing a clean, functional work space and recording detailed information about my samples for quality control and accurate calculations later on. Here are the big three tasks!

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1) Fixing Equipment & ‘Building’ Automation
I never expected that I would wire electricity for soil sensors or build a PVC manifold when I started graduate school. I’m not an engineer! But I’ve spent countless hours acting as a plumber, electrician, engineer, and technician over the past few years. Sometimes I am working to fix equipment worth more money than I owe in student loans. I’ve had to troubleshoot issues on a gas chromatograph, ion chromatograph, and flow injection system. At other times, I’ve worked on building my own equipment to make a job easier. When I was doing greenhouse experiments, I created a vacuum manifold to pull soil solution samples from 40+ soil units at once. We also use PVC columns to wash sand, which I’ve re-caulked on several occasions. I’ve really enjoyed being able to think through technical issues and troubleshoot, but it would be okay if things went smoothly every now and then. I wouldn’t complain!

2) Cleaning Glassware
As you can imagine, accurate soil chemistry requires a clean and sterile environment so that samples are not contaminated. We have a multi-step process that requires soaking dishes in soapy water, rinsing, soaking dishes in dilute hydrochloric acid (HCl), soaking dishes in ultra-pure water, and finally rinsing and letting the dishes air dry. Even when we order new glassware, like beakers, flasks, etc., we always run the materials through this process so that we can eliminate any contamination when we move to the next step. Any guesses on the only material that we can’t run through the acid bath? It’s metals! If we were to put metals in the acid, they would start to corrode. Metal spatulas and weighing dishes only go through the steps that don’t require acid washing. When undergraduate technicians work in the lab, this is often their responsibility, but right now, our lab doesn’t have any helpers. Even if it’s a pain, I know that it is super important to thoroughly prepare the materials that I’m using in the lab so that I can produce sound data.

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3) Weighing Soil Samples
Another way that we ensure that we’re producing sound data is by knowing exactly how much soil is in each of our samples when we start chemical analyses. Running soil tests is similar to a recipe. It often starts by dictating how much of each “ingredient” is required for the test. On Great British Bake Off, they weigh their ingredients really precisely, but in my kitchen, I sort of just throw things together (perhaps why I’m not a contestant on a reality cooking show). In the lab, I try to be a bit more precise and know exactly how much soil I’m weighing into each of my sample containers. For example, the procedures may call for 5 g of soil. My scale will allow me to weight exactly 5.0000 grams, but it would take so long for me to make 500+ samples weigh exactly that amount. Instead, I get as close as I can to 5 g and then record the exact weight of each sample. When I finish procedures, I can account for the different weights in my calculations. Similar to thoroughly washing glassware, weighing out soil samples exactly allows me to produce good scientific data. Of course, I’m always introducing human error when recording weights, transferring samples, taking readings on machines, converting values, etc., but there are steps I take to eliminate this error.

Hopefully, this explains a little more about the not-so-exciting work that I do in the laboratory. One of these weekends, I’ll try to show you the fun stuff - running samples on a machine, getting results, and telling you what those numbers mean for the ducks that use my wetlands! Until then, thanks for letting me share my rather boring weekends with you. Cheers!