Mickie Brown '21

Summer Research Scholar with David Harbor, Summer 2020

"Estimating soil carbon content of grazing lands in Rockbridge County, Virginia using statistical and machine learning techniques"

I spent this summer working with David Harbor in his Soil Carbon Research lab. This is an ongoing project with the overarching goal of studying, supporting, and educating farmers about regenerative farming practices. The avenue that I chose to explore lies in providing an economic incentive to farmers who adopt regenerative farming practices. These practices have several benefits over conventional farming methods: they require less inputs, can garner more products, and they sequester carbon in the soil over time. By measuring the amount of carbon that a farmer adds to the soil, we can then pay them what is called a ‘carbon credit' for the amount of carbon they have taken out of the atmosphere and stored underground. However, current methods of soil carbon measurement are very time consuming, costly, and inefficient.

Therefore, I decided to explore a range of machine learning and statistical techniques currently being applied to soil carbon content estimation to assess the accuracy of each right here in Rockbridge County. However, before I could do all that I needed to collect some data to analyze. David and I spent the first several weeks narrowing down our sampling sites, getting in contact with local farmers, and collecting preliminary data that we eventually used to select our sampling points. We used a technique called conditioned Latin Hypercube Sampling, which replicates the distributions of a set of geographic input variables in an output sample dataset of specified size, to select 115 sample points across 3 farms in the county. I also spent a sizable portion of my time reading about statistical/machine learning techniques all the way from simple linear regressions to deep learning models to select a suite of techniques that I plan on applying to our sampled data.

Before I can get to all of that I need to process the data that I have collected. As I'm writing this my samples are drying in the Science Center, and as soon as they are desiccated I will begin running them through two processes: one to measure organic carbon and one to measure inorganic carbon. This distinction is particularly important due to the amount of inorganic calcium carbonate in the soils of Rockbridge County. Once that is finished I will begin analyzing the data in preparation for the GSA fall meeting in October, where I will be presenting my work thus far.

Summer Research Scholars
Mickie's work was funded in part by the Edgard Winston Spencer '53 Geology Field Research Fund