Fig. 2. (A) Phosphorus influx and (B) shoot demand per unit of root surface area from the two- to the three-leaf stage of maize as a function of topsoil bulk density (BD_top) and P concentration (P_top). Treatments followed by the same letter are not significantly different at = 0.05. Vertical bars are standard errors. ANOVA: * and ** indicate significance at = 0.05 and 0.01, respectively.