Fig. 1. Schematic diagrams of modifications made to the incubated soil core–ion exchange resin bag technique of DiStefano and Gholz (1986) that were used in (A) 1995, (B) 1996, (C) 1997 and 1998, and (D) the minilysimeter method used in 2000. Diagrams not drawn to scale. (Dimensions are given in Materials and Methods.)