It is to the formation of gypsum in the resulting product that the dryness of the superphosphate is due.
Impure chloride of magnesium mixed with superphosphate of lime.
It has also been used for mixing with superphosphate of lime.
There are even drills for dropping water combined with superphosphate.
The rate at which superphosphate is applied to the soil varies in different parts of the country.
Finally they are watered with water containing molasses and superphosphate of lime, as recommended by Corenwinder.
I do not say that two hundred pounds of superphosphate per acre, drilled in with the seed, will always accomplish this object.
Good results will also follow an application of bone meal or superphosphate at the rate of from 300 to 500 pounds per acre.
But if the phosphate is treated with sulfuric acid it becomes more soluble and this product is sold as "superphosphate."
Sulphuric acid converts the phosphate rock into superphosphate, which is soluble and available for plant use.