Sugar cane was planted on three soil units or sites delineated in a mangrove forest ecosystem in Ogonokom-Abua, Rivers State, Nigeria in the 2009/2010 cropping year. The sites were selected based on their differences in water regime viz: non-flooded, partially flooded and completely flooded on a 6-hourly basis by saline tidewater from the Atlantic Ocean. The experiment was, essentially, to determine the productive capacity of the soils in their natural setting, without any amendment whatsoever. The plants produced the highest growth indices in soil unit 1 followed rather distantly by those in unit II and, lastly, by the ones in unit III. The agricultural potential of older soils that have been uplifted above the tidal flood level represented by soil unit 1 needs to be exploited for the cultivation of sugar cane with imperatives for appropriate management practices to increase the productive capacity of the soils. On the other hand, younger soils in the flood basin such as units II and III in the present study need to be preserved to perform their critical role to protect the mangrove ecosystem in the State, in particular, and elsewhere in the Niger Delta region. [ABSTRACT FROM AUTHOR]