The Collaborative International Dictionary
Superphosphate \Su`per*phos"phate\, n. (Chem.) An acid phosphate.
Superphosphate of lime (Com. Chem.), a fertilizer obtained by trating bone dust, bone black, or phosphorite with sulphuric acid, whereby the insoluble neutral calcium phosphate, Ca3(PO4)2, is changed to the primary or acid calcium phosphate Ca(H2PO4)2, which is soluble and therefore available for the soil.
Wiktionary
n. A fertilizer produced by the action of concentrated sulfuric acid on powdered phosphate rock.
Usage examples of "superphosphate".
It is well known that unleached ashes, mixed either with guano, sulphate of ammonia, or superphosphate, mutually decompose each other, setting free the ammonia of the guano and sulphate of ammonia, and converting the soluble phosphate of the superphosphate of lime into the insoluble form in which it existed before treatment with sulphuric acid.
And in raising tobacco-plants in the seed-bed, I should expect good results from the use of superphosphate, raked into the soil at the rate of three or four lbs.
The ashes and superphosphate of lime was also treated in the same way.
The difference in favor of superphosphate, at the time of hoeing, was very perceptible, even at some distance.
Now, superphosphate of lime is composed necessarily of soluble phosphate of lime and plaster, or sulphate of lime, formed from a combination of the sulphuric acid, employed in the manufacture of superphosphate, with the lime of the bones.
The superphosphate of lime, although a very superior article, and estimated at cost price, in no case paid for itself.
It was for this reason, that sulphate of ammonia, and a purely mineral superphosphate of lime, were used in the above experiments.
These results seem to indicate, that superphosphate of lime stimulates the growth of stalks and leaves, and has little effect in increasing the production of seed.
A turnip-crop grown with superphosphate, can get from the soil much more nitrogen than a crop of wheat.
To the market gardener, or to a farmer who manures heavily common turnips drilled in with superphosphate will prove a valuable crop.
I cannot too earnestly recommend the use of superphosphate as a manure for turnips.
Swede turnips or ruta-bagas, it will usually be necessary, in order to secure a maximum crop, to use a manure which, in addition to superphosphate, contains available nitrogen.
I have said before, superphosphate, when drilled in with the seed, has a wonderful effect in developing the root-growth of the young plants of turnips, and I thought it would have the same effect on lettuce, cabbage, cauliflowers, etc.
In other words, we must use Peruvian guano, or nitrate of soda and superphosphate, or bone-dust, or some other substance that will furnish available nitrogen and phosphoric acid.
I depended entirely on thorough cultivation and artificial fertilizers, such as superphosphate and sulphate of ammonia.