In Hawaii, two potential biofuel crops in Hawaii–sugarcane and napiergrass–may sequester more carbon in soil than is lost to the atmosphere, according to a study published January 4, 2017 in the open-access journal PLOS ONE by Meghan Pawlowski from University of Hawaii Manoa, U.S., and colleagues.
Sugarcane and napiergrass are promising biofuel crops because, like other tropical C4 grasses, they have a large carbon-storing root biomass that could offset carbon-dioxide fluxes occurring during cultivation. To test this, Pawlowski and colleagues monitored conventional sugarcane and non-tilled napiergrass crops in Hawaii over two years, measuring the above- and below-ground biomass and assessing the greenhouse gas flux. In addition, these thirsty crops were grown with either conventional or deficit irrigation, which is half that of the current commercial practice.
The researchers found that by the end of the two-year study, both crops had successfully sequestered more carbon in the soil than was lost from the soil surface the largest component of the greenhouse gases in this case.