Cottonwood (Populus deltoides Bartr. Ex marsh, var. deltoides) a fast growing tree species is now recognized as a source of biomass production for bioenergy. It is also considered a potential plant species for use in bioremediation of polluted sites especially those related to groundwater quality. Ramets (cuttings) of cottonwood clones were planted n 3.8 liter (1 gallon) greenhouse pots separately in 2003 and 2004 with 50 and 22 clones respectively evaluated in each year for root biomass and shool biochemical characteristics. The potting mix for 2003 planting was peatmoss, perlite and coconut fiber (1:1:1) ratio by weight. For the 2004 planting, the potting mix was perlite and peatmoss (2:1 ratio by weight) In both years, granulated slow release fertilizer (Osmoscote)- 10k : 10P:15N was applied to pots four weeks after planting plants were evaluated total Khejdal Nitrogen (TKN), root biomass and the presence or absence of heavy metals. This paper reports on the variation among cottonwood clones for TKN in 2003 and 2004. Preliminary results indicate that there are significant differences among the clones for TKN. No trends were observed for the effect of potting mix on the levels of TKN obtained.