a. _Vitriol peat._ Occasionally a peat is met with which is injurious if applied in the fresh state to crops, from its containing some substance which exerts a poisonous action on vegetation. The principal detrimental ingredients that occur in peat, appear to be sulphate of protoxide of iron,--the same body that is popularly known under the names copperas and green-vitriol,--and sulphate of alumina, the astringent component of alum.
I have found these substances ready formed in large quantity in but one of the peats that I have examined, viz.: that sent me by Mr. Perrin Scarborough; of Brooklyn, Conn. This peat dissolved in water to the extent of 15 _per cent._, and the soluble portion, although containing some organic matter and sulphate of lime, consisted in great part of green-vitriol.
Portions of this muck, when thrown up to the air, become covered with "a white crust, having the taste of alum or saltpeter."
The bed containing this peat, though drained, yields but a little poor bog hay, and the peat itself, even after weathering for a year, when applied, mixed with one-fifth of stable manure to corn in the hill, gave no encouraging results, though a fair crop was obtained. It is probable that the sample analyzed was much richer in salts of iron and alumina, than the average of the muck.
Green-vitriol in minute doses is not hurtful, but rather beneficial to vegetation; but in larger quantity it is fatally destructive.
In a salt-marsh mud sent me by the Rev. Wm. Clift, of Stonington, Conn., there was found sulphate of iron in considerable quantity.
This noxious substance likewise occurred in small amount in swamp muck from E. Hoyt, Esq., New Canaan, Conn., and in hardly appreciable quantity in several others that I have examined. Besides green-vitriol, it is possible that certain organic salts of iron, may be deleterious.
The poisonous properties of vitriol-peats may be effectually corrected by composting with lime, or wood-ashes. By the action of these substances, sulphate of lime, (plaster of Paris) is formed, while the iron separates as peroxide, which, being insoluble, is without deleterious effect on vegetation. Where only soluble organic salts of iron (crenate of iron) are present, simple exposure to the air suffices to render them innocuous.