Soil tests on Spearwood sands can be useful in determining rates of phosphorus to apply. Karrakatta sands are yellow-brown soils that lie further inland. They also support tuart trees in their native state. Like Spearwood sands, they retain phosphorus and in some cases, a soil test of 60 ppm may be adequate. In most cases it is wise to apply phosphorus fertiliser even at this soil test level.
Bassendean sands are grey sands that are further inland.
They, and the associated Gavin and Joel white sands , support banksia and jarrah in their native state. Bassendean sands are low in phosphorus in their native state and applied phosphorus is readily leached below the root zone of the crop. Ultimately, this fertiliser will find its way into water courses and the water table. They may require modification with soil improving agents to allow cropping without causing unacceptable levels of water pollution. Split applications of phosphorus throughout the life of the crop are the best compromise if a soil improving treatment has not been applied.