Examples from the Web for superphosphate
For trees, therefore, it would seem desirable to apply the superphosphate before they are planted, and plow it under.Talks on Manures|Joseph Harris
For manure we sow 2,000 pounds of superphosphate and ground Sitka herring, equal parts of each, to the acre.The Cauliflower|A. A. Crozier
Superphosphate is an acid manure and best suited for use on soils containing lime.
Superphosphate makes dark-colored, thick-leaved, stocky (p. 419) plants.
They do not seem, however, to have been imported for purposes of superphosphate manufacture till a number of years afterwards.Manures and the principles of manuring|Charles Morton Aikman