Abstract

                                Attempts have been made since 1892, both in this Institute and elsewhere, to convert the rich phosphatic material available as nodules in the Tiruchirapalli district of the Madras State into a readily available phosphatic fertilizer. The high con- tent of lime (calcium carbonate) present in the raw material mitigated against its conversion into superphosphate by the usual sulphuric acid treatment. Consequently, the material, inspite of its high total P₂O5 content (25 to 30%), remained unexploited for use as a fertilizer.

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