_The effect of Lime and Salt_ upon land is to _dissolve_ the inert portions of organic matters in the soil, so that plants can suck up their substance into their own composition. Both are highly beneficial, but insufficient to add permanent fertility.
_The effect of guano_, is greater than any other highly concentrated manure ever discovered and applied to any soil. Its benefits are immediate continuous, and unlike lime, without exhausting the soil of its organic matter. Yet its benefits will be increased by the addition of organic manures derived from green crops, straw, or the stable, and the value of these will be greatly increased by the addition of lime, salt and plaster, while any deficiency of phosphates must be supplied by powdered bones or another application of guano.
_The effect of plaster with guano_ is to arrest the excursive disposition of the volatile parts of the guano, and imprison them in the earth until called forth by the growing plants to do the State some service. The following question to the Editor of the American Farmer, and his reply, are to the point in this matter:--
A correspondent says--"As to the question of mixing plaster with guano, there is one question I should like to propose to the editor, viz.--'what will be the effect of sowing guano upon land by itself, and then, the seed being in the ground, giving it a heavy top-dressing of plaster, so as to arrest the 'excursion,' of which so much is said?"
_Reply by the editor._--"The effect of such application of guano and plaster would be, to prevent the waste of the ammonia of the former, as every rain would decompose more or less of the plaster, separate the sulphuric acid from the lime, and the sulphuric acid when liberated, would unite with the ammonia, form a sulphate of ammonia, and hold the latter in reserve to be taken up by the roots of the plants. The presence of plaster with all _organic_ manures, either directly mixed with them, or broadcasted after they may be applied, tends to prevent the escape of their volatile parts. We prefer them together for two reasons,--_first_, because, by bringing the two into _immediate contact_, the action of the plaster is more direct; and _secondly_, because the time and expense of one sowing is thereby saved. We go for saving every way, as time and labor costs money, and we look upon economy as a virtue, which should be practised by all, and especially by husbandmen."