dews, &c."

If used as a top dressing, this change from a carbonate to a sulphate
may be necessary; but not so if well mixed with the soil, particularly
one in which clay predominates. In such a soil it is not even necessary
to adhere to the direction to plow the guano deeply under. If it is but
slightly harrowed in, the nature of the clay is such it will prevent
the escape of the ammonia. If you require phosphates, more than
ammonia, add the superphosphate of lime; but in no case omit the guano.

_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
Phosphor