Shi, W.-J., Shen, B. and Wang, Q.-J. 2014. Effect of ignoring parameterbon the maximum upward flux calculated from the Gardner rational model. Can. J. Soil Sci. 94: 97-103. The maximum upward flux (E_max) of groundwater evaporation can be predicted using the Gardner model. The model is often simplified by neglecting a soil parameter (b). The paper describes methods used to assess the impact of the b parameter on predictions of E_max including or eliminating b in the Gardner model. The results showed that ignoring b always resulted in a higher prediction of E_max; for the same soil, the calculated E_max ignoring b was higher than E_bmax including b, and the difference between the measured E_max and calculated E_bmax was smaller. For different soils, the difference between predicted E_max ignoring b and measured value increased as the soil mean particle size increased (when the water table depth was more than 1 cm). For layered soils, the measured E_max was always smaller than the calculated value, regardless of whether b was included or not. And the difference between the calculated and measured values increased with increasing distance from the sandy soil interlayer in the soil profile to the water table. The main reasons for the difference between the calculated E_bmax considering all parameters and the measured values are discussed based on previous research.