A re-evaluation of the effectivenes of calcined Christmas Island C-grade rock phosphate

Abstract

The influence of calcination temperatures up to 1050�C on the effectiveness of Christmas Island C-grade ore was determined in glasshouse trials with wheat. All calcines were capable of supporting the same maximum yield. Maximum effectiveness, equivalent to one-third that of superphosphate, occurred for calcination temperatures between 450�C and 600�C. Re-evaluation of the results of other workers indicated that a similar value for relative effectiveness applies to their work on a variety of species.