Hawaii eucalyptus plantation

On a long-term sugarcane plantation that was converted to a eucalyptus plantation, researchers found no significant change in soil carbon over an 8-year rotation. Because sugarcane is a C4 plant and eucalyptus a C3, their carbon contributions to the soil could be distinguished. The gains of C3-signature carbon from the eucalyptus approximately balanced the losses of C4-signature carbon accumulated under sugarcane.

Soil Sci. Soc. Am. J. 68:1713–1719 (2004)