The given data on phosphorus concentration in topsoil for four different soil treatments appeared in the article “Fertilisers for Lotus and Clover Establishment on a Sequence of Acid Soils on the East Otago Uplands” (N. Zeal. J. of Exptl. Ag., 1984:

119–129). Use a distribution-free procedure to test the null hypothesis of no difference in true mean phosphorus concentration (mg/g) for the four soil treatments.

I 8.1 5.9 7.0 8.0 9.0 II 11.5 10.9 12.1 10.3 11.9 Treatment III 15.3 17.4 16.4 15.8 16.0 IV 23.0 33.0 28.4 24.6 27.7