“The ash of wheat contains, in 100 parts:

Grain.Straw.
Phosphoric acid50.05.0
Sulphuric acid0.52.7
Carbonic acid
Silica2.567.0
Lime3.55.5
Magnesia11.52.9
Potash30.013.0
Soda, chloride of sodium, oxide of iron, sand, etc.2.04.8
Total100.0100.0

“The mean produce of wheat, per acre, may be estimated at 25 bushels, which, at 60 lbs. per bushel, gives 1,500 lbs.; and as the weight of the straw is generally twice that of the grain, its produce will be 3,000 lbs. According, therefore, to the preceding data, there will be carried away from the soil:

In 1,500 lbs. of the grain25lbs. of mineral food, (in round numbers).
In 3,000 lbs. of the straw150lbs. of mineral food, (in round numbers).
Total175lbs.

“On the average of the analyses, it will be found that the composition of these 175 lbs. is as follows:

In the grain.In the straw.Total.
Phosphoric acid12.5 lbs. 7.5 lbs. 20.0 lbs.
Sulphuric acid 0.1 ” 4.0 ” 4.1 ”
Carbonic acid
Silica0.6 ”100.5 ”101.1 ”
Lime0.9 ” 8.2 ” 9.1 ”
Magnesia2.9 ” 3.0 ” 5.9 ”
Potash7.5 ” 19.5 ” 27.0 ”
Soda, chloride of sodium, oxide of iron, sand, etc.0.5 ” 7.3 ” 7.8 ”
25. lbs.150. lbs.175. lbs.

“The total quantity of ash constituents carried off the land, in an average crop of wheat, thus amounts to only 175 lbs. per acre, whilst a good crop of clover removes as much as 672 lbs.

“Nearly two-thirds of the total amount of mineral in the grain and straw of one acre of wheat, consists of silica, of which there is an ample supply in almost every soil. The restoration of silica, therefore, need not trouble us in any way, especially as there is not a single instance on record, proving that silica, even in a soluble condition, has ever been applied to land, with the slightest advantage to corn, or grass-crops, which are rich in silica, and which, for this reason, may be assumed to be particularly grateful for it in a soluble state. Silica, indeed, if at all capable of producing a beneficial effect, ought to be useful to these crops, either by strengthening the straw, or stems of graminaceous plants, or otherwise benefiting them; but, after deducting the amount of silica from the total amount of mineral matters in the wheat produced from one acre, only a trifling quantity of other and more valuable fertilizing ash constituents of plants will be left. On comparing the relative amounts of phosphoric acid, and potash, in an average crop of wheat, and a good crop of clover-hay, it will be seen that one acre of clover-hay contains as much phosphoric acid, as two and one-half acres of wheat, and as much potash as the produce from five acres of the same crop. Clover thus unquestionably removes from the land very much more mineral matter than does wheat; wheat, notwithstanding, succeeds remarkably well after clover.

“Four tons of clover-hay, or the produce of an acre, contains, as already stated, 224 lbs. of nitrogen, or calculated as ammonia, 272 lbs.

“Assuming the grain of wheat to furnish 1.78 per cent of nitrogen, and wheat-straw, .64 per cent, and assuming also that 1,500 lbs. of corn, and 3,000 lbs. of straw, represent the average produce per acre, there will be in the grain of wheat, per acre, 26.7 lbs. of nitrogen, and in the straw, 19.2 lbs., or in both together, 46 lbs. of nitrogen; in round numbers, equal to about 55 lbs. of ammonia, which is only about one-fifth the quantity of nitrogen in the produce of an acre of clover. Wheat, it is well known, is specially benefited by the application of nitrogenous manures, and as clover carries off so large a quantity of nitrogen, it is natural to expect the yield of wheat, after clover, to fall short of what the land might be presumed to produce without manure, before a crop of clover was taken from it. Experience, however, has proved the fallacy of this presumption, for the result is exactly the opposite, inasmuch as a better and heavier crop of wheat is produced than without the intercalation of clover. What, it may be asked, is the explanation of this apparent anomaly?