Fig. 1 Principal John Mussington surveying the plants. The plot receiving the volcanic ash on the left, and the control plot on the right. Introduction Soil fertility depends on the geological history of the minerals in it, climate, and their management. Oceanic islands are either limestone or volcanic, the only exception being the high granite islands in the Seychelles, an ancient small continental fragment. Most limestone islands, including all atolls, are low and flat and are much drier than the high wet volcanic islands. Volcanic islands are much more fertile, because they are wetter, and because basalt contains an ideal mixture of the nutrient ...