It is sufficient to apply to small measured plots of ground, each say two rods square, known quantities of the fresh, the weathered, and the composted peat in order, by comparison of the growth and weight of the crop, to decide the question of their value.
Peat and its composts are usually applied at rates ranging from 20 to 40 wagon or cart loads per acre. There being 160 square rods in the acre, the quantity proper to a plot of two rods square (= four square rods,) would be one half to one load.
The composts with stable manure and lime, or salt and lime mixture, are those which, in general, it would be best to experiment with. From the effects of the stable manure compost, could be inferred with safety the value of any compost, of which animal manure is an essential ingredient.
One great advantage of the practical trial on the small scale is, that the adaptation of the peat or of the compost to the peculiarities of the soil, is decided beyond a question.
It must be borne in mind, however, that the results of experiments can only be relied upon, when the plots are accurately measured, when the peat, etc., are applied in known quantities, and when the crops are separately harvested and carefully weighed.
If experiments are made upon grass or clover, the gravest errors may arise by drawing conclusions from the appearance of the standing crop. Experience has shown that two clover crops, gathered from contiguous plots differently manured, may strikingly differ in appearance, but yield the same amounts of hay.
The chemical examination of a peat may serve to inform us, without loss of time, upon a number of important points.
To test a peat for soluble iron salts which might render it deleterious, we soak and agitate a handful for some hours, with four or five times its bulk of warm soft water. From a good fresh-water peat we obtain, by this treatment, a yellow liquid, more or less deep in tint, the taste of which is very slight and scarcely definable.
From a vitriol peat we get a dark-brown or black solution, which has a bitter, astringent, metallic or inky taste, like that of copperas.
Salt peat will yield a solution having the taste of salt-brine, unless it contains iron, when the taste of the latter will prevail.