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The Dirt on the Value of Soil

By Erin Jaggard, MSc

[Erin Jaggard photo]

Since the advent of agriculture, soil cultivation has degraded soil quality. One of the many quantitative methods scientists use to measure soil quality is soil organic carbon (SOC) content. Soils under long-term cultivation demonstrate a decrease in SOC levels, whereas soils under conservation cropping systems depict the opposite trend. Lower SOC levels result in a decline in soil quality and increased releases of carbon from soil into the atmosphere. thus, land use and land-use change contribute significantly to rising carbon dioxide (CO2) levels in the atmosphere.

Understanding how land use influences the climate system is the focus of my research group led by Dr. Neal Scott, Department of Geography at Queen’s University.

Land-use change is not the only culprit responsible for rising CO2. The burning of fossil fuels contributes about four times the amount of CO2 to the atmosphere as land-use change. The ideal solution to rising CO2 concentrations and SOC losses would be to find a new energy source that could also enhance SOC. The use of biomass as an energy source is one alternative. Switchgrass, an herbaceous grass species, presents an opportunity to increase SOC stocks. Its harvested biomass can serve as an energy source in several ways, or as a raw material in bio-based products.

Establishing switchgrass in lands previously under long-term cultivation produces exponential increases in SOC and offsets CO2 for a few reasons. First, these crops serve as a soil cover, and thus mitigate erosion. Second, the deep, prolific roots, which can equal the amount of above-ground biomass, sequester carbon.

My research explores the soil processes associated with the capture of carbon in soil following switchgrass establishment in southeastern Ontario. Marginal agricultural lands near major urban centers provide an appropriate geographical venue to cultivate switchgrass as a feasible bioenergy feedstock.

A low-carbon economy, which requires us to evaluate and modify energy policy and global carbon stocks, should consider SOC as a crucial metric. The establishment of a market-based mechanism should reward landowners for the management of soil through conservation agricultural practices. Such practices serve to mitigate climate change and enhance the fertility of our soils for all that soils can provide.

In 2011, to celebrate the 10th Anniversary of the Canada Research Chairs (CRC) program, Queen’s University Vice-Principal (Research) launched a writing contest for current graduate students working with CRCs at Queen’s. Both masters and doctoral students were encouraged to submit entries. The contest sought to showcase the research of a Queen’s CRC through engaging stories that highlighted the successes of students’ research experience and demonstrated the research’s benefits to society. This is an abridged version of one of the winning stories.