Genetically engineered oilcane does not enhance soil carbon losses compared to wild-type sugarcane

Background/Question/Methods

Biofuels have the potential to provide a carbon-neutral fuel source, reduce fossil fuel consumption, and enhance soil carbon sequestration. However, most current bioenergy crops are difficult to convert to fuel. To remedy this, there have been recent efforts to genetically modify crops to allow for more efficient fuel conversion. Oilcane is a genetically modified crop that has been engineered to produce more energy-dense oils and less soluble lignin. These changes in plant chemistry could impact microbial efficiency and activity leading to altered soil carbon dynamics. Our objective was to compare the impacts of oilcane litter and wild-type sugarcane litter on microbial respiration and soil carbon. To do this, we incubated stem and leaf litter from wild-type sugarcane and oilcane plants in microcosms with forest soil. Using differences in natural abundance δ13C between soil and litter we tracked the mineralization and movement of litter and soil-derived carbon into protected and unprotected soil carbon pools.

Results/Conclusions

After eleven weeks, our results showed no significant differences in total respiration (i.e., soil + litter), soil respiration, or litter respiration between plant types. However, jars with stems respired more soil carbon and, therefore, more total carbon than jars with leaves (p< 0.1). There were also no differences in the amount of litter-derived carbon in the protected and unprotected soil carbon pools suggesting similar microbial carbon use efficiencies for both plant types. These results suggest that the genetic modifications to oilcane do not impact microbial activity or soil carbon stabilization, strengthening its potential to be a carbon-neutral fuel source.