To begin the analysis, from the menus choose:

Analyze
 Nonparametric Tests
  2 Independent Samples...

step Select Aflatoxin PPB and Centered aflatoxin level as the test variables.

step Deselect Mann-Whitney U, and select Kolmogorov-Smirnov Z.

step Select Corn yield as the grouping variable.

step Click Define Groups.

step Type 4 as the group 1 value and 8 as the group 2 value.

step Click Continue.

step Click OK in the Two-Independent-Samples Tests dialog box.