Statistical experiments were made to ascertain the effect of variations in applied soluble phosphate on the growth of Milan Strap-leaved Purple Top Turnips in a light gravel soil already containing sufficient available phosphate, and in a fen soil possessing an inadequate supply of available phosphate, as aggregates for growth.

No adverse effect on yield, calculated as fresh or dry matter of tops, roots, or whole plants, was suffered in either soil at any of the stages of growth considered at the highest concentrations of soluble phosphate, unlike the behaviour of this turnip when grown in a pure sand containing no clays or humates, where there was a narrow optimum range of phosphorus at a low concentration. The gravel soil occupied an intermediate position, however, between sand with its low optimum range of soluble phosphorus, and fen soil, where positive response to increasing concentrations of soluble phosphorus approached the ‘normal’, and thus there was a range of phosphorus at low concentration tending to a maximum yield followed generally by a greater numerical yield at the highest concentrations of phosphorus.

At the seedling stage in gravel soil variation in applied phosphate had absolutely no statistical effect on yield, moisture content of tops, roots and whole plants, and the ratios, for fresh or dry matter, Top/Root, Root/(Whole plant) and (Whole plant)/ Top.