A repeated measures ANOVA of total organic C (TOC) in the growth chamber experiment showed a statistically significant 3-way (clone by fertilizer by drought) interaction (p < 0.05). One clone increased exudation with fertilization under low irrigation, but reduced exudation under high irrigation. The other clone reduced exudation under low irrigation, but increased exudation under high irrigation. Furthermore, the clone that displayed greater stem volume growth also showed significantly less (p < 0.10) exudation in the form of anthrone reactive C (ARC). ARC represents highly labile C sources, such as simple carbohydrates. In the field study, four clones tested for root-specific exudation rates showed significant differences (p < 0.10) in TOC exudation. There was no significant fertilizer or clone by fertilizer interaction in the field trial. Overall, these results support our second hypothesis; there is significant variability in exudation between clones. However, interpretations regarding our first hypothesis appear to depend both on genotype and water relations. Some clones reduce exudation with fertilizer application, while others do not. These differences may be partially responsible for the observed range of stem volume responses to fertilizer application.