Research Alert
A multi-institutional team of scientists evaluated how differences in root traits in varieties of switchgrass and big bluestem affected the amount of carbon accumulation in soil. Their results showed that careful selection of both species and varieties can help improve bioenergy crop management while maximizing the amount of carbon in soil and lowering carbon emissions.
The team collected soil cores from the Department of Energy (DOE) National Environmental Research Park in Batavia, Illinois, from six varieties of grass. They measured root biomass, root diameter, specific root length, bulk soil carbon, and carbon associated with coarse particulate organic matter and fine particulate organic matter plus silt- and clay-sized fractions of soil. They then characterized organic matter chemical class composition using high-resolution Fourier-transform ion cyclotron resonance mass spectrometry at EMSL, the Environmental Molecular Sciences Laboratory, a DOE Office of Science User Facility. They found that big bluestem grass had higher plant-derived carbon compared to switchgrass in the coarse particulate organic matter fraction of the soil to a depth of 10 cm, while switchgrass had higher plant-derived carbon in the clay fraction between 10 and 20 cm deep. The findings suggest that, after 10 years of growth, the large root system in big bluestem helps rapidly increase soil carbon formation in the form of particulate organic matter, while switchgrass root structure and chemistry contribute to building a mineral-bound clay carbon pool.
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