The influence of growth location, variety, and harvest time on ash composition and calorific value of cassava stems was evaluated using 180 samples from a full factorial-designed experiment (three locations x three varieties x five harvest times) in Guangxi, China. The calorific value of cassava stems showed only small variations (<3%). However, the ash content and ash-forming elements, such as P, Cl, S, K, Ca, and Mg, varied significantly with location, variety, and harvest time. A ternary diagram analysis of major elements indicated cassava stems had rather high ash-fusion temperatures (>1500 degrees C), which was consistent with our published results(18,19) and suggested limited sintering during combustion, if any. K and Cl contents varied the most and did so significantly between locations (growth environments), which was attributed to differences in soil composition. On the basis of theoretical and empirical indices of molar ratios, cassava stems across all treatments generally exhibited a risk of particle emissions when combusted but stems from one location (Heng) could have much better combustion behavior than those from others in terms of slagging and corrosive Cl-rich deposit tendencies indicated by the indices K/(Ca + Mg) and combinations of S/Cl and Cl/(K + Na), respectively. Stems from Wuming showed a higher risk for the induction of particle emission, according to the index (K + Na + Ca + Mg)/(P + Si), while biomass from Longan and the variety Xinxuan048 tended to show risk of forming corrosive Cl-rich deposits.