Use of Salt with Guano.—Common salt at the rate of a bushel to 100 lbs. of guano, well mixed, may be used to good advantage either as a top dressing, or when plowed in. The effect of the muriatic acid of the salt upon the guano will be, as both are dissolved in the earth, or by dews and rains, to form muriate of ammonia, which is not volatile; consequently the salt prevents loss by exhaustion, which is sure to take place when the guano is used as a top dressing, unless prevented by something to act as a fixer of the ammonia.
The wisdom of this law of nature in making the most precious saline manure a fixed and difficultly soluble salt, is at once obvious; for it is thus kept always ready in the soil for the plants to act upon according to their need. If we cut plants down before the seeds form, we have all the phosphates the plants contain diffused throughout them, and if we allow the seed to ripen, the phosphates, as before observed, will be found mostly in the seed. We find them in the state of phosphate of potash, phosphate of soda, phosphate of magnesia, and phosphate of lime, and probably, also, phosphate of ammonia. Now all these salts are essential to the growth and sustenance of animals, and without them grain would cease to be sufficient.
The necessity of restoring inorganic substances to the soil, may be better understood by examining the following table:
Mr. Prixdeaux states that the following quantities (of inorganic matters) are removed from an acre of soil by a crop of wheat, of 25 bushels of grain, and 3000 lbs. of straw—
| By the grain. | By the straw. | Total. | |
|---|---|---|---|
| lbs. | lbs. | lbs. | |
| Potash, | 7.15 | 22.44 | 29.59 |
| Soda, | 2.73 | 0.29 | 3.02 |
| Magnesia, | 3.63 | 6.99 | 10.62 |
| Phosphoric acid, | 15.02 | 5.54 | 20.56 |
| Sulphuric acid, | 0.07 | 10.49 | 10.56 |
| Chlorine | 0.00 | 1.98 | 1.98 |
| —— | —— | —— | |
| 28.60 | 47.73 | ||
| Gross weight to be returned to an acre, | 76.33 |
Professor Johnson says—"Soils are barren either from the presence of a noxious principle or the absence of a necessary element. It is therefore highly important to be able to distinguish between the two cases.
"The art of culture is almost entirely a chemical art. Its processes are explained on chemical principals in part, but partly on mechanical and natural ones.
"All forms of matter may be divided into one of the two great groups—organic or inorganic matter."
In Peruvian guano, both these substances exist in a better and cheaper form than can be obtained from any other source.
The editor of the Genesee farmer, whose scientific information none can dispute, strongly corroborates this opinion. In a late number he says—If we admit that phosphate of lime is a necessary ingredient in a special manure for wheat—Peruvian guano would at present be much the cheapest source of it; for, in addition to the 16 per cent. of ammonia, it contains 20 per cent. of phosphate of lime in first-rate condition for assimilation by the plant, as well as other fertilizing ingredients of minor importance.