Biochar Weathering and the Carbon Cycle

Students

2019
College

Faculty

Professor
College

Project Summary

I worked in the Earth and Environmental Science Department under the mentorship of Dr. Alain Plante.  My project focused on the role of biochar in the global carbon cycle.  Biochar is a form of pyrogenic carbon, or black carbon, produced via the incomplete combustion of biomass. My project consisted of analyzing soil and char samples from an agricultural field trial to try to understand the effects of weathering on the biochar. 

Biochar occurs naturally as a result of wildfire, so understanding how this char interacts with soils and the atmosphere is important for improving understanding of the carbon cycle. In order to analyze the carbon in the chars and soils, I first had to prepare the soils and chars by sieving and then grinding portions of the samples.

I prepared a series of leachates from each char and soil fraction. During leaching, soluble carbon forms in the sample come out into water and remain in the solution after filtering the solid back out.  I was then able to analyze the concentration and forms of carbon in the leachate (the water solution) via photospectroscopy. Learning the wavelengths at which the leachates absorb light tells us about the structures carbon takes within the soil and char as it weathers over time. The amount of soluble carbon helps indicate the residence time of carbon in this biochar. It tells us for how long carbon remains sequestered in the char or soil after the char is created (or added to the soil as in the case of soil amendments).

This research will help us understand how biochar interacts with the surrounding soil and environment. Knowing the forms of carbon and for how long these forms are stable will help us understand how pyrogenic carbon functions in the carbon cycle. It will also help us understand how biochar may be used as a soil amendment to improve soil fertility and productivity, or how the optimal production of biochar may serve to sequester carbon from the atmosphere to mitigate the effects of climate change.

Biochar Weathering and the Carbon Cycle